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  • 1990-1994  (142)
  • 1955-1959  (17)
  • somaclonal variation
  • transformation
  • 1
    Electronic Resource
    Electronic Resource
    Agrobacterium-mediated transformation of white mustard (Sinapis alba L.) and regeneration of transgenic plants (1994)
    Springer
    Plant cell reports 13 (1994), S. 130-134 
    Details
    ISSN: 1432-203X
    Keywords: Sinapis alba L. ; Agrobacterium tumefaciens ; transformation ; regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A procedure for the regeneration of fertile transgenic white mustard (Sinapis alba L.) is presented. The protocol is based on infection of stem explants of 7–9 day old plants with an Agrobacterium tumefaciens strain harboring a disarmed binary vector with chimeric genes encoding neomycin phosphotransferase and β-glucuronidase. Shoots are regenerated from callus-forming explants within 3–4 weeks. Under selection, 10% of the explants with transgenic embryonic callus develop into fertile transgenic plants. Rooting shoots transferred to soil yield seeds within 14–16 weeks following transformation. Integration and expression of the T-DNA encoded marker genes was confirmed by histochemical β glucuronidase assays and Southern-DNA hybridization using primary transformants and S1-progeny. The analysis showed stable integration and Mendelian inheritance of trans-genes in transformed Sinapis lines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239878
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  • 2
    Electronic Resource
    Electronic Resource
    Isolation and transformation of rice aleurone protoplasts (1994)
    Springer
    Plant cell reports 13 (1994), S. 394-396 
    Details
    ISSN: 1432-203X
    Keywords: Rice ; α-amylase ; protoplasts ; aleurone ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Protoplasts isolated from the aleurone have been used extensively in molecular studies focusing on hormone-mediated regulation of gene expression in barley seed. To extend the use of aleurone protoplasts to other species, we have determined the conditions necessary for the isolation of protoplasts from rice aleurone layers of germinated seed. Many of the common cell wall degrading enzymes used in making protoplasts were tested for their ability to release protoplasts from rice aleurone layers. Cellulysin was found to be the most effective. Transformation of these aleurone protoplasts was accomplished using polyethylene glycol and DNA constructs containing the firefly luciferase reporter gene under the control of two different promoters were tested. Luciferase expression was 24-fold greater when the reporter gene was under the control of the CaMV 35S promoter than when the promoter from the alcohol dehydrogenase 1 gene was used. With the isolation and transformation of aleurone protoplasts from rice, it is now possible to investigate molecular events occurring in this tissue during germination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234145
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  • 3
    Electronic Resource
    Electronic Resource
    Hairy roots of Brassica napus: II. Glutamine synthetase overexpression alters ammonia assimilation and the response to phosphinothricin (1994)
    Springer
    Plant cell reports 14 (1994), S. 41-46 
    Details
    ISSN: 1432-203X
    Keywords: Agrobacterium rhizogenes ; Brassica napus ; glutamine synthetase ; phosphinothricin ; rape ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Hairy roots of Brassica napus (rape cv. Giant) have been produced that contain the cytosolic glutamine synthetase (GS) gene from Glycine max (soybean). Leaf explants were cocultivated with Agrobacterium rhizogenes strain A4T harbouring the binary vector pLN16. This vector was constructed by inserting a soybean cytosolic GS cDNA into the multiple cloning site of pGA643, placing it under the control of the CaMV promoter. In addition, the T-DNA region of pLN16 contained a NPTII gene for selection of transformed cells. Transgenic hairy roots grew prolifically on hormone-free media containing a selective level of kanamycin. Southern and northern analyses confirmed the presence of soybean GS DNA and transcripts, respectively. These transformed hairy roots also have a greater abundance of the GS polypeptide, approximately 3–6 fold greater GS activity and lower levels of endogenous ammonia. Hairy roots provide a useful system for studying responses to phosphinothricin (PPT). Hairy roots grown in media containing PPT had lower GS activity, greater ammonia accumulation and slower growth than controls. The presence of the soybean GS gene in the hairy roots reduced these PPT-induced effects and resulted in higher GS activity, lower ammonia levels and faster growth than in PPT-treated controls. Greater tolerance of PPT was also seen in shoots regenerated from the hairy roots displaying elevated levels of GS activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233296
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  • 4
    Electronic Resource
    Electronic Resource
    Genetic ecology: A new interdisciplinary science, fundamental for evolution, biodiversity and biosafety evaluations (1994)
    Springer
    Cellular and molecular life sciences 50 (1994), S. 429-437 
    Details
    ISSN: 1420-9071
    Keywords: Genetics ; ecology ; DNA-transfer ; conjugation ; transformation ; transduction ; transposons ; dormant cells ; epilithon ; microbial colonisation ; symbiosis ; virus resistance ; biosafety ; release of genes ; insults to humanity ; evolution ; biodiversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Genetic ecology is the extension of our modern knowledge in molecular genetics to studies of viability, gene expression and gene movements in natural environments like soils, aquifers and digestive tracts. In such milieux, the horizontal transfer of plasmid-borne genes between phylogenetically distant species has already been found to be much more frequent than had been expected from laboratory experience. For the study of exchanges involving chromosomally-located genes, more has to be learned about the behaviour of transposons in such environments. The results expected from studies in genetic ecology are relevant for considerations of evolution, biodiversity and biosafety. The role of this new field of research in restoring popular confidence in science and in its biotechnological applications is stressed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01920741
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  • 5
    Electronic Resource
    Electronic Resource
    Stable expression of the GUS reporter gene in chrysanthemum depends on binary plasmid T-DNA (1994)
    Springer
    Plant cell reports 14 (1994), S. 59-64 
    Details
    ISSN: 1432-203X
    Keywords: Agrobacterium ; transformation ; T-DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three chrysanthemum (Dendranthema grandiflora) cultivars were cocultivated with 2 Agrobacterium tumefaciens strains in combination with 4 pBIN19 derived binary plasmids, all carrying the Nosnptll selection gene and 35Sgus(intron) reporter gene. All binary plasmids transferred DNA to chrysanthemum explants but only pMOG410 gave good stable expression of GUS. This plasmid differs from the other plasmids in 2 aspects: 1) It carries a restored nptll gene and 2) the selection gene is positioned at the left border side of the reporter gene. Cocultivation with AGLO(pMOG410) yielded up to 13 GUS positive shoots per 100 explants. The presence of the gus and nptll gene in recovered shoots was confirmed by PCR and Southern blot analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233300
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  • 6
    Electronic Resource
    Electronic Resource
    Plasmid mediated silver resistance in Acinetobacter baumannii (1994)
    Springer
    BioMetals 7 (1994), S. 49-56 
    Details
    ISSN: 1572-8773
    Keywords: Acinetobacter ; conjugation ; curing ; plasmid ; silver uptake ; silver resistance ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Acinetobacter baumannii BL88, an environmental isolate, was resistant to 13 metals and 10 antibiotics. Plumbagin cured resistance to silver, cadmium, antimony, streptomycin and ampicillin at varying frequencies. However, only silver resistance transferred (1 × 10−6 recepient−1) to Escherichia coli K12 during conjugation. Correspondingly there was transfer of a 54 kb plasmid (pUPI199) from A. baumannii BL88. The plasmid transformed E. coli DH5α cells at a frequency of 1 × 10−8 recepient−1. The growth rate of E. coli DH5; (pUPI199) was slower as compared with E. coli DH5α. Plasmid pUPI199 was 76 and 9.6% stable in the host A. baumannii BL88 in the presence and absence of selection pressure, respectively. A. baumannii BL88 was found to accumulate and retain silver whereas E. coli DH5α (pUPI199) effluxed 63% of the accumulated silver ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00205194
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  • 7
    Electronic Resource
    Electronic Resource
    Transmission of injected DNA sequences to multiple eggs of Metaseiulus occidentalis and Amblyseius finlandicus (Acari: Phytoseiidae) following maternal microinjection (1994)
    Springer
    Experimental and applied acarology 18 (1994), S. 319-330 
    Details
    ISSN: 1572-9702
    Keywords: Maternal microinjection ; transformation ; genetic improvement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The persistence of DNA injected into two species of adult female phytoseiids and its transmission to serial eggs deposited by them was assessed by the polymerase chain reaction (PCR). The effect of DNA concentration on persistence and transmission was examined in Metaseiulus occidentalis. M. occidentalis females were microinjected with plasmid DNA at three different concentrations (250, 500, 750 ng μL−1) and allowed to deposit one to five eggs before the females and their last eggs were analyzed. Plasmid DNA was found in 82% of the females assayed and in 70% of all the eggs analyzed (including the fifth eggs produced after microinjection). Transmission of DNA to multiple eggs was also examined in Amblyseius finlandicus. Females of this species are less traumatized by microinjection allowing analysis of transmission over a more extended number of eggs. Females were microinjected and allowed to deposit eggs until their death. DNA from every fifth egg was analyzed by the PCR. PCR products were amplified from 51% of the eggs and from all egg classes except the 30th egg. The persistence and presence of plasmid DNA in both eggs and females suggests that (1) maternal microinjection is a more efficient method for DNA delivery than traditional egg microinjection, (2) it may be possible to isolate transformants from fewer maternally-microinjected females than originally expected, and (3) maternal microinjection could be useful as a DNA delivery system in other phytoseiids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00116313
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  • 8
    Electronic Resource
    Electronic Resource
    Canonical correlation and reduction of multiple time series (1994)
    Springer
    Annals of the Institute of Statistical Mathematics 46 (1994), S. 625-631 
    Details
    ISSN: 1572-9052
    Keywords: Rank of multiple time series ; transformation ; spectrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract It is shown that a degenerate rankd-variate stationary time series can be reduced to a full rank time series of lower dimension via an orthogonal transformationT provided that ρ, the canonical correlation between past and future of the time series is strictly less than one. Procedures for estimation of rank of the multiple time series,T and testing ρ=1 are outlined, the latter is related to testing the unit root hypothesis in ARMA models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00773471
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  • 9
    Electronic Resource
    Electronic Resource
    Genetics and gibberellin production inGibberella fujikuroi (1994)
    Springer
    Antonie van Leeuwenhoek 65 (1994), S. 217-225 
    Details
    ISSN: 1572-9699
    Keywords: Gibberella fujikuroi ; gibberellins ; mutants ; regulation by nitrogen ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gibberella fujikuroi (Fusarium moniliforme) is a complex group of plant pathogens. Some strains produce gibberellic acid and other gibberellins that promote growth and regulate various stages in plant development. The paper describes the research effort directed to development of genetic tools for this species. Furthermore the main features of the gibberellin biosynthetic pathway as established in Gibberella are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00871950
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  • 10
    Electronic Resource
    Electronic Resource
    Transgenic plants: performance, release and containment (1994)
    Springer
    World journal of microbiology and biotechnology 10 (1994), S. 139-144 
    Details
    ISSN: 1573-0972
    Keywords: Gene flow ; insertion mutagenesis ; marker genes ; pleiotropy ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract This review focuses on transgenic plants, from the initial stages of the genetic modification process in the laboratory to their release stage in the field and indicates possible areas of concern and strategies for dealing with them. The classes of marker genes and issues about their safety, the gene flow and strategies that are used to isolate transgenic plants genetically are specifically examined. In addition, an assessment is provided of the phenomena which affect the performance of transgenic plants, such as gene disruption, the pleiotropic effect on plant phenotype and genetic variation. Finally, strategies are suggested for preventing unexpected consequences of transgenic plant production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00360874
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  • 11
    Electronic Resource
    Electronic Resource
    Efficient plant regeneration through somatic embryogenesis from callus induced on mature rice embryos (Oryza sativa L.) (1994)
    Springer
    Plant cell, tissue and organ culture 36 (1994), S. 259-264 
    Details
    ISSN: 1573-5044
    Keywords: monocotyledons ; Oryza sativa L. ; plant regeneration ; rice ; somatic embryogenesis ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To obtain a reproducible efficient procedure for regeneration of rice plants through somatic embryogenesis from callus four published methods of callus induction and regeneration were compared. Callus was initiated from mature embryos of the Japonica cultivar Taipei 309 of rice (Oryza sativa L.). The number, mass and morphology of the callus formed on the scutellum were dependent on the medium used. A limited humidity and an optimal aeration of the culture vessels enhanced the frequency of embryogenesis and plant regeneration. A method described by Poonsapaya et al. (1989) was found to be the most efficient and was slightly modified. As a result 98% of the T309 embryos formed callus, of which 63% regenerated into plants. Each callus yielded an average of 6 plants. Plant morphology, fertility and seed set of the regenerants were found to be normal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00037729
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  • 12
    Electronic Resource
    Electronic Resource
    Factors that effect leaf regeneration efficiency in apple, and effect of antibiotics in morphogenesis (1994)
    Springer
    Plant cell, tissue and organ culture 37 (1994), S. 257-269 
    Details
    ISSN: 1573-5044
    Keywords: adventitious shoots ; Malus x domestica Borkh. ; tissue culture ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several factors that affect the frequency of organogenesis in apple leaf explants were examined for the scion cultivars ‘Empire’, ‘Freedom’, ‘Golden Delicious’, ‘Liberty’, ‘McIntosh’, and ‘Mutsu’ and for the rootstocks Malling 7A and Malling 26. The main factors affecting morphogenesis were BA concentration, basal medium, leaf explant origin and maturity, explant orientation, and photosynthetic photon flux. Depending on the genotype, optimal regeneration was obtained using either 22.2 or 31.1 μM BA and the N6 basal medium, with the exception of ‘Golden Delicious’ which regenerated better on MS medium. After 6 weeks, the average number of shoots per segment varied from 5 to 16, and the percentage of regeneration between 70 and 100%, depending on the genotype tested and the maturity of the explant. Regeneration capacity increased dramatically from the tip towards the base of the leaf, and was higher from the middle to the proximal end. Cefotaxime and carbenicillin, two antibiotics commonly used during transformation studies to eliminate Agrobacterium tumefaciens from plant tissue, were tested to determine their effect on morphogenesis. Cefotaxime at a dose of 250 mg 1-1 enhanced regeneration and shoot development, whereas carbenicillin at a dose of 500 mg l-1 induced abundant callus formation and inhibited regeneration. Kanamycin, a widely used selection agent for plant transformation, strongly inhibited regeneration even at very low doses. Schemes for selection and recovery of transgenic apple plants when kanamycin is used as the selection agent are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042339
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  • 13
    Electronic Resource
    Electronic Resource
    A robust protocol for site-directed mutagenesis of the D1 protein inChlamydomonas reinhardtii: A PCR-splicedpsbA gene in a plasmid conferring spectinomycin resistance was introduced into apsbA deletion strain (1994)
    Springer
    Photosynthesis research 42 (1994), S. 121-131 
    Details
    ISSN: 1573-5079
    Keywords: chloroplast ; Photosystem II ; psbA ; site-directed mutagenesis ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this paper, we describe a protocol to obtain a site-directed mutants in thepsbA gene ofChlamydomonas reinhardtii, which overcomes several drawbacks of previous protocols, and makes it possible to generate a mutant within a month. Since the large size of the gene, and the presence of four large introns has made molecular genetics of thepsbA gene rather unwieldy, we have spliced all of the exons of thepsbA gene by PCR to facilitate genetic manipulation and sequencing of the gene. The resultant construct (plasmid pBA153, with several unique restriction sites introduced at exon boundaries) carried 1.2 and 1.8 kb intact sequences from the 5′- and 3′-flanking regions, respectively. The plasmid was used to transform a D1-deletion mutant and was found to complement the deletion and restore photosynthetic activity. In addition, a bacterialaadA gene conferring spectinomycin resistance (spe r) was inserted downstream of the intron-freepsbA gene, to give construct pBA155. This allowed selection of mutant strains deficient in photosynthesis by using spectinomycin resistance, and eliminated the possibility of selection for revertant strains which is a consequence of having to use photosynthetic activity as a selection pressure. Finally, pBA155 was used to construct pBA157, in which additional restriction sites were inserted to facilitate cassette mutagenesis for generation of mutations in spans thought to be involved in donor-side interactions. AllpsbA deletion strains transformed with intron-freepsbA-aadA constructs encoding the wild-type D1 sequence, and screened on spectinomycin plates for thespe r phenotype, were able to grow photosynthetically, and all showed identical kinetics for electron transfer from primary (QA) to secondary quinone (QB) in Photosystem II, as assayed by the decay of the high fluorescence yield on oxidation of the reduced primary acceptor (QA −).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02187123
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  • 14
    Electronic Resource
    Electronic Resource
    Micropropagation of thirteen Malus cultivars and rootstocks, and effect of antibiotics on proliferation (1994)
    Springer
    Plant growth regulation 15 (1994), S. 55-67 
    Details
    ISSN: 1573-5087
    Keywords: apple (Malus × domestica Borkh.) ; selection ; tissue culture ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Several factors that affect in vitro establishment, proliferation, and rooting of thirteen Malus cultivars and rootstocks were studied. Apple shoot tips (1.5±0.5 cm in length) were established using ascorbic and citric acids as antioxidants. Four proliferation media containing 1.0 mg 1−1 BA and different concentrations of IBA and GA3 were tested. Proliferation rates varied depending on the genotype and medium used. The highest proliferation rate was obtained for a rootstock that produced 11.6±2.5 shoots (1.5±0.8 cm in length) per tube per month. Rooting was induced with IBA for all the genotypes tested. The optimal IBA concentration was cultivar dependent (between 0.1 and 1.0 mg 1−1 IBA), and lower concentrations were necessary to induce rooting in liquid rather than in solid medium. The effects on shoot-tip proliferation of cefotaxime, carbenicillin and kanamycin, three antibiotics commonly used for transformation studies, were also evaluated. Cefotaxime at 200 mg 1−1 stimulated shoot growth and development, but at 500 mg 1−1 caused abnormal shoot morphology. Carbenicillin at 500 mg 1−1, alone or in combination with cefotaxime at 200 mg 1−1, inhibited proliferation and caused excessive enlargement of the basal leaves, inducing callus formation and release of phenolic compounds in the medium. Kanamycin at 50 mg 1−1 was phytotoxic and caused shoot chlorosis and necrosis. Consideration of the toxicity of these antibiotics is critical when designing transformation schemes for selection and recovery of transgenic apple plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024677
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  • 15
    Electronic Resource
    Electronic Resource
    Production of fertile transgenic maize by electroporation of suspension culture cells (1994)
    Springer
    Plant molecular biology 24 (1994), S. 51-61 
    Details
    ISSN: 1573-5028
    Keywords: Zea mays L. ; transformation ; electroporation ; bar ; phosphinothricin acetyltransferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fertile, transgenic maize plants were generated by electroporation of suspension culture cells that were treated with a pectin-degrading enzyme. Electroporation of cells from two different suspension cultures, one derived from A188 X B73 and one derived from a B73-related inbred, with a plasmid containing the bar gene, resulted in high-frequency recovery of stably transformed callus lines. Plants were regenerated from thirteen transformed callus lines and transmission of bar to progeny was demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00040573
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  • 16
    Electronic Resource
    Electronic Resource
    Stable transformation and long-term expression of the gusA reporter gene in callus lines of perennial ryegrass (Lolium perenne L.) (1994)
    Springer
    Plant molecular biology 24 (1994), S. 401-405 
    Details
    ISSN: 1573-5028
    Keywords: Lolium perenne L. ; transformation ; rice gene GOS2 ; long-term GUS expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stable transformation of perennial ryegrass (Lolium perenne L.) was achieved by biolistic bombardment of a non embryogenic cell suspension culture, using the hpt and gusA gene. The transformation yielded on the average 5 callus lines per bombardment (1.4×106 cells). Stable integration of the genes into the plant genome was demonstrated by Southern analysis of DNA, isolated from hygromycin-resistant callus lines. The gusA reporter gene, which was regulated by the constitutive promoter of the rice gene GOS2, was expressed in both transient and stable transformation assays, indicating that this promoter is suitable for expression of a transferred gene in perennial ryegrass. Long-term GUS expression was observed in ca. 40% of the callus lines, whereas the other callus lines showed instability after 6 months and 1 year of culture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020178
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  • 17
    Electronic Resource
    Electronic Resource
    Molecular improvement of cereals (1994)
    Springer
    Plant molecular biology 25 (1994), S. 925-937 
    Details
    ISSN: 1573-5028
    Keywords: cereals ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014667
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  • 18
    Electronic Resource
    Electronic Resource
    Structure and function of selectable and non-selectable transgenes in maize after introduction by particle bombardment (1994)
    Springer
    Plant molecular biology 25 (1994), S. 951-961 
    Details
    ISSN: 1573-5028
    Keywords: Cell biology ; epigenetics ; maize ; transformation ; transgenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zea mays transformants produced by particle bombardment of embryogenic suspension culture cells of the genotype A188 × B73 and selected on kanamycin or bialaphos were characterized with respect to transgene integration, expression, and inheritance. Selection on bialaphos, mediated by thebar orpat genes, was more efficient than selection on kanamycin, mediated by thenptII gene. Most transformants contained multicopy, single locus, transgene insertion events. A transgene expression cassette was more likely to be rearranged if expression of that gene was not selected for during callus growth. Not all plants regenerated from calli representing single transformation events expressed the transgenes, and a non-selectable gene (uidA) was expressed in fewer plants than was the selectable transgene. Mendelian inheritance of transgenes consistent with transgene insertion at a single locus was observed for approximately two thirds of the transformants assessed. Transgene expression was typically, but not always, predictable in progeny plants-transgene silencing, as well as poor transgene transmission to progeny, was observed in some plant lines in which the parent plants had expressed the transgene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014669
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  • 19
    Electronic Resource
    Electronic Resource
    Stably transformed cell lines from protoplasts of maize endosperm suspension cultures (1994)
    Springer
    Plant cell, tissue and organ culture 37 (1994), S. 39-46 
    Details
    ISSN: 1573-5044
    Keywords: endosperm cell culture ; maize ; protoplast ; transformation ; zeins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protoplasts were isolated from Zea mays (L.) A69Y endosperm suspension cultures and transformed by polyethylene glycol mediated DNA uptake with chimaeric gene constructs containing β-glucuronidase (GUS) or neomycin phosphotransferase II (NPTII); GUS-expressing and Kanamycin-resistant cultures were recovered. The transformed cells showed integration of the introduced foreign genes into genomic DNA and maintained their ability to synthesize endosperm-specific reserve proteins (zeins). No deletion or rearrangement of zein genes were observed in transformed cultures. Stable transformation of cultured maize endosperm cells may therefore represent a new methodological approach for the study of the transcriptional regulation of endosperm-expressed genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048115
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  • 20
    Electronic Resource
    Electronic Resource
    Genetic control of frost tolerance in wheat (Triticum aestivum L.) (1994)
    Springer
    Euphytica 77 (1994), S. 277-282 
    Details
    ISSN: 1573-5060
    Keywords: Wheat ; frost tolerance ; diallel cross ; monosomics ; Triticum aestivum ; chromosome substitutions ; wild species ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The frost tolerance of winter wheat is one component of winter hardiness. If seedlings are frost resistant, it means that they can survive the frost effect without any considerable damage. To study the genetic control of frost tolerance, an artificial freezing test was used. Frost tolerance is controlled by an additive-dominance system. The results of diallel analyses indicate the importance of both additive and non-additive gene action in the inheritance of this character. The dominant genes act in the direction of lower frost tolerance and the recessive genes in the direction of a higher level of frost tolerance. The results of monosomic and substitution analyses show that at least 10 of the 21 pairs of chromosomes are involved in the control of frost tolerance and winter hardiness. Chromosomes 5A and 5D have been implicated most frequently. The geneFr1 (Frost 1) was located on the long arm of chromosome 5A. Crosses between cultivars, chromosome manipulation and the induction of somaclonal variation may be suitable methods for broadening the gene pool for frost tolerance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262642
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  • 21
    Electronic Resource
    Electronic Resource
    Somaclonal variation for resistance to Verticillium dahliae in potato (Solanum tuberosum L.) plants regenerated from callus (1994)
    Springer
    Euphytica 80 (1994), S. 5-11 
    Details
    ISSN: 1573-5060
    Keywords: disease resistance ; filtrate selection ; Solanum tuberosum (cvs Désirée, Kondor) ; somaclonal variation ; Verticillium dahliae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Plant tissue culture is recognized as an important tool to generate useful genetic variability for crop improvement. Regenerated plants from callus induced from stem explants of Solanum tuberosum cv Désirée were assessed by in vitro selection, for resistance to Verticillium dahliae. This fungus is the causal agent of Verticillium wilt, a serious vascular wilt disease both in crops and wild species. The rate of in vitro multiplication by single node cuttings was used as a parameter of screening in two selection cycles with different concentrations of V. dahliae filtrate. One resistant clone was selected and then evaluated by inoculation in the growth chamber. Induced damage, and morphological traits (dry weight, leaf area and tuber production) were estimated. The selected clone was comparable to the resistant control, cv Kondor. The results suggest that genetic variation induced in tissue culture cound be utilized to generate disease resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00039292
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  • 22
    Electronic Resource
    Electronic Resource
    A simple technique for producing 13C or 14C-labelled fronds of Lemna gibba and their use in soil incubation investigations (1994)
    Springer
    Plant and soil 160 (1994), S. 185-191 
    Details
    ISSN: 1573-5036
    Keywords: carbon-labelling ; carbon dioxide production ; decomposition ; 14C-glucose ; Lemna ; soil organic matter ; sugars ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The duckweed Lemna gibba required light and a suitable energy source such as sucrose, glucose or fructose, for maximum growth in culture. The requirement for light was relatively unimportant and the plants grew well in a photon flux density of only 52 μmol m-2s-1 PAR. The uptake and incorporation of uniformly labelled 14C-glucose into fronds was related only to the concentration of the sugar. When incubated with soil, labelled L. gibba behaved in a manner similar to that of labelled ryegrass roots which had been produced by a more elaborate technique using a 14CO2 labelled atmosphere. During incubation with soil for 224 days the L. gibba material (specific activity 6133 Bq mg-1 d. wt) lost 64% of its radioactivity as 14CO2 and ryegrass (specific activity 6634 Bq mg-1 d. wt) lost 49%. Alkaline extracted humic and fulvic acids from soil had specific activities for the L. gibba incubation of 3409 and 407 Bq mg-1 solid and for ryegrass roots of 4609 and 546 Bq mg-1 solid respectively. The production of 13C or 14C-labelled L. gibba can be undertaken using only simple equipment producing material the specific radioactivity of which can be controlled by adjusting the activity of the sugar energy source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010144
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  • 23
    Electronic Resource
    Electronic Resource
    Stability of bacterial leaf spot resistance in peach regenerants under in vitro, greenhouse and field conditions (1994)
    Springer
    Euphytica 76 (1994), S. 101-106 
    Details
    ISSN: 1573-5060
    Keywords: in vitro selection ; Prunus persica ; somaclonal variation ; Xanthomonas campestris pv. pruni ; bacterial leaf spot of peach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Phenotypic stability of bacterial leaf spot resistance in peach (Prunus persica (L.) Batsch) regenerants, either selected at the cellular level for insensitivity to a toxic culture filtrate of Xanthomonas campestris pv. pruni or screened at the whole plant level for resistance to X. campestris pv. pruni, was investigated. A detached-leaf bioassay was used to evaluate the original regenerants again after three years in the greenhouse and also after a two to three year cycle of tissue culture propagation. Peach trees derived through micropropagation from the original regenerants were also evaluated after one to three years growth in the field. Although leaf spot resistance was retained in some regenerants over time in the greenhouse, following in vitro propagation, and under field conditions, resistance was either lost or not expressed in others. Regenerants # 19-1 and #156-6, derived from embryo callus of bacterial spot susceptible ‘Sunhigh’, were significantly more resistant than ‘Sunhigh’. High levels of resistance were exhibited in greenhouse plants and field-grown trees of regenerant #122-1, derived from embryo callus of moderately resistant ‘Redhaven’. This research provides additional evidence that selecting or screening for somaclonal variants with disease resistance is a feasible approach to obtaining peach trees with increased levels of bacterial spot resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024026
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  • 24
    Electronic Resource
    Electronic Resource
    Inheritance of male sterility mutations induced in haploid sorghum tissue culture (1994)
    Springer
    Euphytica 80 (1994), S. 111-118 
    Details
    ISSN: 1573-5060
    Keywords: somaclonal variation ; cytoplasmic inheritance ; cytoplasmic male sterility ; fertility restorer genes ; Sorghum bicolor (L.) Moench ; sorghum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A high frequency of male sterile mutants regeneration was shown in callus cultures derived from leaves and panicles of haploid sorghum (Msc1, A1 cytoplasm) and a spontaneous autodiploid obtained from this haploid. The cultures derived from the embryos of this autodiploid yielded significantly fewer mutants. Absolutely or partially male sterile mutants appeared among the regenerants or in the progeny of fertile regenerants. In the self-fertilized progenies of partially male sterile mutants and in the hybrids of sterile mutants with autodiploid line (i.e. under one and the same nuclear genome) male sterility mutations were inherited as cytoplasmic. Non-Mendelian segregation of sterile, partially male sterile and fertile plants was observed in these progenies. Partially male sterile plants were characterized by somatic segregation of male sterility genetic factors. In test-crosses with some CMS A1 fertility restorers, mutations were manifested as nuclear recessive while with others as nuclear dominant. These differences are supposed to be the result of interaction of fertility restorer genes of these testers with the novel cytoplasm. Male sterility mutations accompanied with female sterility were inherited as nuclear recessives.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00039305
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  • 25
    Electronic Resource
    Electronic Resource
    Cloning of ω3 desaturase from cyanobacteria and its use in altering the degree of membrane-lipid unsaturation (1994)
    Springer
    Plant molecular biology 26 (1994), S. 249-263 
    Details
    ISSN: 1573-5028
    Keywords: desB gene ; desaturase ; fatty acid ; Synechococcus sp. PCC 7942 ; Synechocystis sp. PCC 6803 ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cyanobacteria respond to a decrease in temperature by desaturating fatty acids of membrane lipids to compensate for the decrease in membrane fluidity. Among various desaturation reactions in cyanobacteria, the desaturation of the ω3 position of fatty acids is the most sensitive to the change in temperature. In the present study, we isolated a gene, designated desB, for the ω3 desaturase from the cyanobacterium, Synechocystis sp. PCC 6803. The desB gene encodes a protein a 359 amino-acid residues with molecular mass of 41.9 kDa. The desB gene is transcribed as a monocistronic operon that produced a single transcript of 1.4 kb. The level of the desB transcript in cells grown at 22°C was 10 times higher than that in cells grown at 34°C. In order to manipulate the fatty-acid unsaturation of membrane lipids, the desB gene in Synechocystis sp. PCC 6803 was mutated by insertion of a kanamycin-resistance gene cartridge. The resultant mutant was unable to desaturate fatty acids at the ω3 position. The desA gene, which encodes the Δ12 desaturase of Synechocystis sp. PCC 6803, and the desB gene were introduced into Synechococcus sp. PCC 7942. Whilst the parent cyanobacterium can only desaturate membrane lipids at the Δ9 position of fatty acids, the resultant transformant was able to desaturate fatty acids of membrane lipids at the Δ9, Δ12 and ω3 positions. These results confirm the function of the desB gene and demonstrate that it is possible to genetically manipulate the fatty-acid unsaturation of membrane lipids in cyanobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00039536
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  • 26
    Electronic Resource
    Electronic Resource
    Identification of conserved domains in the Δ12 desaturases of cyanobacteria (1994)
    Springer
    Plant molecular biology 24 (1994), S. 643-650 
    Details
    ISSN: 1573-5028
    Keywords: Anabaena variabilis ; fatty-acid desaturation ; Synechococcus PCC7002 ; Synechococcus PCC7942 ; Synechocystis PCC6714 ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cyanobacterial genes for enzymes that desaturate fatty acids at the Δ12 position, designated desA, were isolated from Synechocystis PCC6714, Synechococcus PCC7002 and Anabaena variabilis by crosshybridization with a DNA probe derived from the desA gene of Synechocystis PCC6803. The genes of Synechocystis PCC6714, Synechococcus PCC7002 and A. variabilis encode proteins of 349, 347 and 350 amino acid residues, respectively. The transformation of Synechococcus PCC7942 with the desA genes from Synechocystis PCC6714, Synechococcus PCC7002 and A. variabilis was associated with the ability to introduce a second double bond at the Δ12 position of fatty acids. The amino acid sequence of the products of the desA genes revealed the presence of four conserved domains. Since one of the conserved domains was also found in the amino acid sequences of ω3 desaturases of Brassica napus and mung bean, this domain may play an essential role in the introduction of a double bond into fatty acids bound to membrane lipids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023560
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  • 27
    Electronic Resource
    Electronic Resource
    Directed disruption of the Chlamydomonas chloroplast psbK gene destabilizes the photosystem II reaction center complex (1994)
    Springer
    Plant molecular biology 24 (1994), S. 779-788 
    Details
    ISSN: 1573-5028
    Keywords: Chlamydomonas reinhardtii ; chloroplast ; transformation ; photosystem II ; psbK
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using particle gun-mediated chloroplast transformation we have disrupted the psbK gene of Chlamydomonas reihardtii with an aadA expression cassette that confers resistance to spectinomycin. The transformants are unable to grow photoautotrophically, but they grow normally in acetate-containing medium. They are deficient in photosystem II activity as measured by fluorescence transients and O2 evolution and they accumulate less than 10% of wild-type levels of photosystem II as measured by immunochemical means. Pulse-labeling experiments indicate that the photosystem II complex is synthesized normally in the transformants. These results differ from those obtained previously with similar cyanobacterial psbK mutants that were still capable of photoautotrophic growth (Ikeuchi et al., J. Biol. Chem. 266 (1991) 1111–1115). In C. reinhardtii the psbK product is required for the stable assembly and/or stability of the photosystem II complex and essential for photoautotrophic growth. The data also suggest that the stability requirements of the photosynthetic complexes differ considerably between C. reinhardtii and cyanobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029859
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  • 28
    Electronic Resource
    Electronic Resource
    Cotton (Gossypium hirsutum L.) pollen-specific polygalacturonase mRNA: tissue and temporal specificity of its promoter in transgenic tobacco (1994)
    Springer
    Plant molecular biology 26 (1994), S. 1989-1993 
    Details
    ISSN: 1573-5028
    Keywords: polygalacturonase ; pollen-specific promoter ; cotton ; transgenics ; transformation ; β-glucuronidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A gene (G9) expressed during late microsporogenesis in cotton (Gossypium hirsutum L.) was isolated. Sequence analysis of the cDNA (1.3 kb) as well as the gene (2.6 kb) revealed an open reading frame of 1233 bases encoding a protein of 43.9 kDa. The coding region of the gene is interrupted by three introns. Northern analysis of the RNA from developing anthers showed that the transcripts appear 12 days before anthesis and that the maximal concentration of RNA occurs in pollen on the day of anthesis. This pattern of gene expression suggests functions in post-anthesis events. Sequence comparisons with other known plant genes indicated that G9 is homologous to polygalacturonases. The G9 promoter conferred tissue and temporal specificity of β-glucuronidase (GUS) expression in transgenic tobacco plants. Thus, the G9 promoter can be used to drive gene expression in homologous as well as heterologous plants in a tissue-specific manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019509
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  • 29
    Electronic Resource
    Electronic Resource
    Initial acytokinesis during leaf protoplast culture of dihaploid and tetraploidSolanum tuberosum and diploidS. bulbocastanum (1994)
    Springer
    Potato research 37 (1994), S. 413-421 
    Details
    ISSN: 1871-4528
    Keywords: somaclonal variation ; chromosome number ; potato ; polyploidization ; aneuploidization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Leaf protoplasts of dihaploid (2n=2x=24) and tetraploid (2n=4x=48)Solanum tuberosum, and diploidS. bulbocastanum (2n=2x=24) were cultured in liquid medium. The cultures were studied for early karyological changes during their development. Giemsa staining of spread preparations revealed extremely low percentages of protoplasts developing into calli with the parental chromosome number, and high percentages of acytokinetic cells. The nuclear divisions within a cell were synchronous which allowed the occurrence of spindle interaction, resulting in nuclear poly- and aneuploidization. Although polyploidization was also found in uninucleate cells, a major increase in the formation of true-to-type calli would certainly be established by the improvement of early cross wall formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02358355
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  • 30
    Electronic Resource
    Electronic Resource
    In what situations isin vitro culture appropriate to plant conservations? (1994)
    Springer
    Biodiversity and conservation 3 (1994), S. 176-183 
    Details
    ISSN: 1572-9710
    Keywords: conservation ; cryopreservation ; in vitro culture ; micropropagation ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Variousin vitro techniques are available for plant propagation, including seed germination, micropropagation, meristem culture and callus culture. The role of these techniques in the conservation of endangered plants is discussed, using examples drawn from the work of the Micropropagation Unit at Kew.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02291887
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  • 31
    Electronic Resource
    Electronic Resource
    An assessment of gene transfer by pollen from field-grown transgenic potatoes to non-transgenic potatoes and related species (1994)
    Springer
    Transgenic research 3 (1994), S. 216-225 
    Details
    ISSN: 1573-9368
    Keywords: Solanum tuberosum ; genetic modification ; transformation ; gene transfer ; genetic isolation ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Information on the extent of transgene dispersal by pollen to adjacent potato plots and to related weed species is an important requisite for risk assessment; a procedure followed before novel transgenic plants are evaluated under field conditions. The purpose of the investigation was to determine the frequency of cross-pollination between potato (Solanum tuberosum) plants at different distances, using a kanamycin resistnace transgene (nptII) as a selectable marker. All potato plants were from the variety Désirée. Non-transgenic potato plants, used as potential recipients of transgene-containing pollen, were planted in 12 sub-plots, at distances of 0–20 m from the nearest transgenic potato plants. Seeds harvested from the non-transgenic plants were screened for resistance to kanamycin, and molecular methods were used to confirm that resistant progeny contained thenptII gene. Where transgenic and non-transgenic potato plants were in alternate rows (leaves touching), 24% of seedlings from the non-transgenic parent plants were kanamycin-resistant. Comparable seedlings from plants at up to 3 m distance had a resistance frequency of 2%, at 10 m the frequency was 0.017% and at 20 m no resistant progeny were observed. Plants of the weed speciesS. dulcamara andS. nigrum were also planted close to the transgenic potatoes to test for evidence of hybridization, and no kanamycin-resistant seedlings were observed among progeny fromS. dulcamara andS. nigrum. This investigation provided evidence that the extent of gene dispersal from transgenic potatoes to non-transgenic potatoes falls markedly with increasing distance, and is negligible at 10 m. There was, also, no evidence of transgene movement from potato toS. dulcamara andS. nigrum under field conditions. These data will be valuable in defining genetic isolation procedures for the early field evaluation and the use of novel transgenic potato genotypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02336774
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  • 32
    Electronic Resource
    Electronic Resource
    T-DNA-insert-independent mutations induced in transformed plant cells duringAgrobacterium co-cultivation (1994)
    Springer
    Transgenic research 3 (1994), S. 317-325 
    Details
    ISSN: 1573-9368
    Keywords: Agrobacterium ; mutagenesis ; Nicotiana plumbaginifolia ; nitrate reductase ; ploidy ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transformation frequencies were determined for 1n, 2n, and 4n Nicotiana plumbaginifolia protoplast cultures inAgrobacterium-mediated gene transfer experiments. An unexpected large drop (50%) in plating efficiencies was observed in the non-selected (control) 1n populations after transformation treatment with virulent strains. This effect was not observed in the 2n or 4n cultures or in the 1n cultures when treated with avirulent bacteria. The mortality was disproportionally high and could not be explained by the low (0.1–0.5%) transformation efficiency in the 1n population, indicating mutagenesis of the cell populations independently from the T-DNA insertions. Mutagenesis was also indicated in gene tagging experiments where nitrate reductase-deficient (NR−) mutants were selected from haploidNicotiana plumbaginifolia protoplasts, as well as from leaf disc cultures or protoplasts of diploid plants that were heterozygotic for a mutation either in the NR apoenzyme gene (nia/wt) or one of the molybdenum-containing cofactor genes (cnxA/wt), afterAgrobacterium co-cultivation. The chlorate-resistant isolates were tested for the T-DNA-specific kanamycin resistance trait only after NR-deficiency had been established. Thirty-nine independent NR-deficient mutants were analysed further by Southern blot hybridization. There was no indication of integrated T-DNA sequences in the mutated NR genes, despite the fact that NR-deficient cells were found more frequently in cell populations which became transformed during the treatment than in the populations which did not. These observations suggest that transformation-competent cells undergo mutagenesis during theAgrobacterium gene transfer process not only as a result of stable integration events, but also through accompanying events that do not result in major changes in the mutated loci. The nature of these changes at the molecular level remains to be elucidated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01973592
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  • 33
    Electronic Resource
    Electronic Resource
    Recombinant viruses as transformation vectors of marine macroalgae (1994)
    Springer
    Journal of applied phycology 6 (1994), S. 247-253 
    Details
    ISSN: 1573-5176
    Keywords: algae ; genes ; recombinant ; transformation ; vectors ; viruses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The large dsDNA viruses that are known to infect eukaryotic algae show promise as genetic vectors for algal biotechnology. The large size (150–330 kbp) of these viral genomes may permit insertion of large sequences of foreign DNA. The viruses infecting filamentous marine brown algae appear to be integrated into the genomes of their hosts, and may provide integration mechanisms that can be used for directing insertion of foreign genes into algal chromosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02186078
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  • 34
    Electronic Resource
    Electronic Resource
    Some features about transposition of the maize elementDissociation inNicotiana plumbaginifolia (1994)
    Springer
    Genetica 93 (1994), S. 41-48 
    Details
    ISSN: 1573-6857
    Keywords: Ac/Ds ; transformation ; transgenic plants ; transposon tagging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have recently shown that a plasmid-borneDissociation (Ds) element can excise from extrachromosomal plasmid DNA and integrate into a plant genome in the presence of theActivator (Ac) transposase.Ds andAc-carrying plasmids were used to co-transformNicotiana plumbaginifolia protoplasts. Transgenic plants were regenerated and analyzed. Here we describe further characterization of the system and discuss its efficiency in terms of DNA transformation and transposon tagging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01435238
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  • 35
    Electronic Resource
    Electronic Resource
    Different tumorigenicity of cell clones derived from stromal fibroblasts of human colon cancer xenografts (1994)
    Springer
    Bulletin of experimental biology and medicine 118 (1994), S. 879-882 
    Details
    ISSN: 1573-8221
    Keywords: fibroblasts ; xenografts ; thymus-free animals ; transformation ; immortalization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The tumorigenicity of cell clones derived from fibroblast lines isolated from colon cancer xenografts is studied in thymus-free animals. During cloning of the cell line obtained from the 3rd passage of the xenograft about 20% of the clones proved to be nontumorigenic, whereas such cells were not found in the line obtained from the 89th passage. Cytogenetic analysis of nontumorigenic clones revealed monosomy for the 13th chromosome with no alterations in the other chromosome pairs. Hybridization for the presence of Alu sequences was negative.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02444455
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  • 36
    Electronic Resource
    Electronic Resource
    Maintenance and expression of heterologous genes in chloroplast ofChlamydomonas reinhardtii (1994)
    Springer
    Journal of applied phycology 6 (1994), S. 239-245 
    Details
    ISSN: 1573-5176
    Keywords: Chlamydomonas reinhardtii ; transformation ; chloroplast ; aminoglycoside adenine transferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chloroplast genome ofChlamydomonas reinhardtii has been transformed with a chimeric gene consisting of the chloroplastatpA promoter and the bacterial gene for aminoglycoside adenine transferase (aadA). TheatpA-aadA cassette has been placed within the chloroplast DNAEcoRI restriction enzyme fragment 14, or within the chloroplastBamH1 fragment 10. The chimeric constructs were introduced into the chloroplast by particle bombardment. Integration of the cassette into chloroplast DNA then occurred via homologous recombination of sequences flanking the cassette with their corresponding chloroplast sequences. We demonstrate that the chloroplastatpA promoter inatpA-aadA routinely recombines with its endogenous counterpart, resulting in heteroplasmic chloroplast DNA populations that may persist for many generations. The heterologous gene does not require a 3′ inverted repeat sequence for its expression. TheatpA-aadA gene copy number, which is dictated here by its position in the chloroplast genome, is proportional to the steady state level ofatpA-aadA mRNA. However, neither genomic position, gene copy number, or mRNA level have a significant effect on cellular resistance to spectinomycin, nor activity of theaadA gene productin vitro. These results suggest that, in the case ofaadA, the limiting step for expression of this gene is at the translational or post-translational level. TheatpA-aadA cassette should prove a useful model for future studies on the maintenance and expression of heterologous genes inC. reinhardtii chloroplasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02186077
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  • 37
    Electronic Resource
    Electronic Resource
    Biomethylation and biotransformation of arsenic in a freshwater food chain: Green alga (chlorella vulgaris)→shrimp (neocaridina denticulata)→killifish (oryzias iatipes) (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 8 (1994), S. 325-333 
    Details
    ISSN: 0268-2605
    Keywords: Arsenic ; methylation ; transformation ; freshwater food chain ; green alga ; shrimp ; killifish ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tolerance, bioaccumulation, biotransformation and excretion of arsenic compounds by the fresh-water shrimp (Neocaridina denticulata) and the killifish (Oryzias latipes) (collected from the natural environment) were investigated. Tolerances (LC50) of the shrimp against disodium arsenate [abbreviated as As(V)], methylarsonic acid (MAA), dimethylarsinic acid (DMAA), and arsenobetaine (AB) were 1.5, 10, 40, and 150μg As ml-1, respectively.N. denticulata accumulated arsenic from an aqueous phase containing 1 μg As ml-1 of As(V), 10 μg As ml-1 of MAA, 30 μg As ml-1 of DMAA or 150 μg As ml-1 of AB, and biotransformed and excreted part of these species. Both methylation and demethylation of the arsenicals were observed in vivo. When living N. denticulata accumulating arsenic was transferred into an arsenic-free medium, a part of the accumulated arsenic was excreted. The concentration of methylated arsenicals relative to total arsenic was higher in the excrement than in the organism.Total arsenic accumulation in each species via food in the food chainGreen algae (Chlorella vulgaris)→ shrimp (N. denticulata)→ killifish (O. latipes)decreased by one order of magnitude or more, and the concentration of methylated arsenic relative to total arsenic accumulated increased successively with elevation in the trophic level. Only trace amounts of monomethylarsenic species were detected in the shrimp and fish tested. Dimethylarsenic species in alga and shrimp, and trimethylarsenic species in killifish, were the predominant methylated arsenic species, respectively.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590080407
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  • 38
    Electronic Resource
    Electronic Resource
    Selectable marker replacement in Saccharomyces cerevisiae (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 10 (1994), S. 141-149 
    Details
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; selectable marker ; transformation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Selectable markers integrated by the ‘gamma’ deletion method (Sikorski and Hieter, 1989) can be efficiently replaced in vivo with other markers by transformation with homologous plasmids. Transformation frequencies in experiments designed to replace original selectable markers with an alternate marker were high and molecular analysis confirmed that all transformants that exhibited the expected phenotypes (loss of the original prototrophy and gain of the alternate prototrophy) resulted from homologous recombination between plasmid sequences at the target locus. This technique involves no plasmid construction and greatly facilitates the generation of yeast cells containing multiple gene disruptions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320100202
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  • 39
    Electronic Resource
    Electronic Resource
    Enhanced transformation of tomato co-cultivated with Agrobacterium tumefaciens C58C1Rifr::pGSFR1161 in the presence of acetosyringone (1993)
    Springer
    Plant cell reports 12 (1993), S. 422-425 
    Details
    ISSN: 1432-203X
    Keywords: Acetosyringone ; Agrobacterium tumefaciens ; tomato ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Explants of tomato (Lycopersicon esculentum Mill cv. Ailsa Craig) were co-cultivated with Agrobacterium tumefaciens C58C1Rifr::pGSFR1161 in the presence of 20 (μM acetosyringone). Transformed root clones were selected on kanamycin medium and the presence of the nptII gene in the plant DNA confirmed by the polymerase chain reaction. Root clones derived from acetosyringone treatment grew more vigorously in the presence of kanamycin and synthesized a greater amount of NPT-II enzyme. The conclusion is that acetosyringone treatment enhances the transformation process, possibly by stimulating multiple insertions of the T-DNA into the host genome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234705
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  • 40
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    Analysis of genetic stability of plants regenerated from suspension cultures and protoplasts of meadow fescue (Festuca pratensis Huds.) (1993)
    Springer
    Plant cell reports 12 (1993), S. 101-106 
    Details
    ISSN: 1432-203X
    Keywords: Festuca pratensis ; suspension cultures ; protoplasts ; plant regeneration ; somaclonal variation ; genetic fidelity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cytological and molecular analysis was performed to assess the genetic uniformity and true-to-type character of plants regenerated from 20 week-old embryogenic suspension cultures of meadow fescue (Festuca pratensis Huds.), and compared to protoplastderived plants obtained from the same cell suspension. Cytological variation was not observed in a representative sample of plants regenerated directly from the embryogenic suspensions and from protoplasts isolated therefrom. Similarly, no restriction fragment length polymorphisms (RFLPs) were detected in the mitochondrial, plastid and nuclear genomes in the plants analyzed. Randomly amplified polymorphic DNA markers (RAPDs) have been used to characterise molecularly a set of mature meadow fescue plants regenerated from these in vitro cultures. RAPD markers using 18 different short oligonucleotide primers of arbitrary nucleotide sequence in combination with polymerase chain reaction (PCR) allowed the detection of pre-existing polymorphisms in the donor genotypes, but failed to reveal newly generated variation in the protoplast-derived plants compared to their equivalent suspensionculture regenerated materials. The genetic stability of meadow fescue plants regenerated from suspension cultures and protoplasts isolated therefrom and its implications on gene transfer technology for this species are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241943
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  • 41
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    Stable transformation of the food yam Dioscorea alata L. by particle bombardment (1993)
    Springer
    Plant cell reports 12 (1993), S. 468-473 
    Details
    ISSN: 1432-203X
    Keywords: Dioscorea alata ; GUS ; transformation ; particle gun
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A biolistic particle gun was used to deliver genetic material into intact yam cells. Cultured suspension cells of D. alata were bombarded with microprojectiles coated with pBI221.2 DNA and histochemical assays were carried out to show transient GUS expression in bombarded cells. Stably transformed D. alata cells were recovered from cultured cells after bombardment with microprojectiles coated with pRT99gus harbouring both the nptII and uidA genes. Bombarded cells were selected on a medium containing geneticin (G418). Two months after bombardment, calli resistant to G418 were assayed for GUS expression. There was a 100% correlation between resistance to G418 and GUS expression. From these calli, four cell lines were established and GUS activity in each line was determined fluorometrically. The use of a specific GUS inhibitor showed that the GUS activity was due to the introduced uidA gene rather than to any intrinsic GUS-like activity originating from the plant. Incorporation of the introduced DNA into the plant genomic DNA was confirmed by Southern analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234714
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  • 42
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    Transformation of maize (Zea mays L.) protoplasts and regeneration of haploid transgenic plants (1993)
    Springer
    Plant cell reports 13 (1993), S. 63-68 
    Details
    ISSN: 1432-203X
    Keywords: Zea mays L ; microspore-derived cultures ; haploid ; regeneration ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transgenic haploid maize (Zea mays L.) plants were obtained from protoplasts isolated from microspore-derived cell suspension cultures. Protoplasts were electroporated in the presence of plasmid DNA containing the gus A and npt II genes encoding ß-glucuronidase (GUS) and neomycin phosphotransferase II (NPT II), respectively. Transformed calli were selected and continuously maintained on kanamycin containing medium. Stable transformation was confirmed by enzyme assays and DNA. analysis. Stably transformed tissue was transferred to regeneration medium and several plants were obtained. Most plants showed NPT II activity, and some also showed GUS activity. Chromosome examinations performed on representative plants showed that they were haploid. As expected, these plants were infertile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235291
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  • 43
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    Restoring adventitious shoot formation on chrysanthemum leaf explants following cocultivation with Agrobacterium tumefaciens (1993)
    Springer
    Plant cell, tissue and organ culture 32 (1993), S. 263-270 
    Details
    ISSN: 1573-5044
    Keywords: Dendranthema grandiflora ; preculture ; regeneration ; transformation ; β-glucuronidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Explants from leaves of in vitro-grown chrysanthemum (Dendranthema grandiflora Tzvel.) cultivars regenerated adventitious shoots without an intermediate callus phase. Puncturing explants with a brush increased regenerations, but in combination with cocultivation with Agrobacterium tumefaciens it had an adverse effect on shoot formation. The negative effect of brushing and cocultivation could be overcome by preculturing explants for 8 days. Preculture altered the location of transformed sites but did not inhibit transformation. Regeneration following cocultivation with Agrobacterium is also encouraged if alternative regeneration protocols are used that do not require brushing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042287
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  • 44
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    Electronic Resource
    Genetic engineering of grain and pasture legumes for improved nutritive value (1993)
    Springer
    Genetica 90 (1993), S. 181-200 
    Details
    ISSN: 1573-6857
    Keywords: plant ; genetic engineering ; nutritive value ; agrobacterium ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This review describes work aimed at the improvement of the nutritive value of grain and forage legumes using gene transfer techniques. Two traits which are amenable to manipulation by genetic engineering have been identified. These are plant protein quality and lignin content. In order to increase the quality of protein provided by the legume grains peas and lupins, we are attempting to introduce into these species chimeric genes encoding a sunflower seed protein rich in the sulphur-containing amino acids methionine and cysteine. These genes are designed to be expressed only in developing seeds of transgenic host plants. Chimeric genes incorporating a similar protein-coding region, but different transcriptional controls, are being introduced into the forage legumes lucerne and subterranean clover. In this case the genes are highly expressed in the leaves of transformed plants, and modifications have been made to the sunflower seed protein-coding sequences in order to increase the stability of the resultant protein in leaf tissue. Another approach to increasing plant nutritive value is represented by attempts to reduce the content of indigestible lignin in lucerne.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01435039
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  • 45
    Electronic Resource
    Electronic Resource
    Solvent effect on the inclusion of 2-acetylnaphthalene by 1,1-di(p-hydroxyphenyl)cyclohexane (1993)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 15 (1993), S. 27-36 
    Details
    ISSN: 1573-1111
    Keywords: Crystallization ; nucleation ; crystal growth ; polymorph ; molecular complex ; transformation ; solvent effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of the solvents acetone (AT), dimethylsulfoxide (DMSO) and methylcellosolve (MCS) on the inclusion of 2-acetylnaphthalene (2-AN) in the host, 1,1-di(p-hydroxyphenyl)cyclohexane (DHC) has been investigated. Each solvent molecule is included in DHC in a molar ratio of 1.0, when DHC is crystallized from the solvents. The evaporation rate of these solvents from the host lattice decreases in the order AT, MCS and DMSO. The order agrees well with the interaction strength between the host and solvent molecule, which was measured by DSC and IR. 2-AN cannot be included in the crystals by crystallization from MCS and DMSO solutions. However, in AT solution both AT and 2-AN are included competitively and the morphology of the crystals is different from that obtained in pure solution. The amount of 2-AN in the crystals increases continuously with its concentration in solution. This behavior indicates that AT is replaced by 2-AN and the solid solution of the molecular complex is formed. The solid solution is a metastable form and the solution-mediated tranformation to the stable form (which includes only AT) was observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00706471
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  • 46
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    Electronic Resource
    The role of endogenous auxin in root initiation (1993)
    Springer
    Plant growth regulation 13 (1993), S. 77-84 
    Details
    ISSN: 1573-5087
    Keywords: Agrobacterium rhizogenes ; auxin ; indole-3-acetic acid (IAA) ; root initiation ; sensitivity ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper is the second part of a review which considers evidence for the involvement of auxin in root initiation. Part II examines the research being carried out with transformed plant tissues. Agrobacterium rhizogenes causes abundant root initiation at the site of inoculation. Ri plasmid T-DNA contains several genes which encode enzymes involved in the biosynthesis and metabolism of indole-3-acetic acid. Transfer of various fragments of the Ri plasmid has also been reported to confer increased sensitivity to auxin upon plant cells. Controlled expression of these genes in the plant genome potentially offer an insight for developmental plant physiologists into the role of plant growth substances in the process of root initiation. The importance of absolute levels of IAA in the stimulation of root initiation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00207595
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  • 47
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    Electronic Resource
    Somaclonal variation within poplar (1993)
    Springer
    Plant cell, tissue and organ culture 35 (1993), S. 99-106 
    Details
    ISSN: 1573-5044
    Keywords: Hypoxylon mammatum ; Melampsora ; Populus spp. ploidy ; somaclonal variation ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract One thousand and ninety-two poplars were regenerated in vitro from callus of 13 poplar clones representing the Leuce, Aigeiros and Tacamahaca sections. At lest 44 of the regenerants differed in some way from the original clones. Somaclonal variation occurred more frequently in poplars of the Leuce section (8%) than in those of the Aigeiros or Tacamahaca sections (1%). Variation was noticed in growth habit, leaf shape or indentation but not in the reaction to four Melampsora races. However, after one growing season in the field, a few regenerants from calli of two clones (‘Ogy’ and ‘Rap’) differed in their susceptibility vis à vis the original clones. Cultivation of callus from Leuce poplars that had survived exposure to increasing concentrations of toxins from Hypoxylon mammatum gave rise to a toxin-tolerant line from which toxin tolerant plants were regenerated. Flow cytometry to measure the DNA content of nuclei showed that regenerants tended to be tetraploid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00043946
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  • 48
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    Semi-constitutive expression of an Arabidopsis thaliana α-tubulin gene (1993)
    Springer
    Plant molecular biology 21 (1993), S. 937-942 
    Details
    ISSN: 1573-5028
    Keywords: α-tubulin ; Arabidopsis ; β-glucuronidase ; gene expression ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Arabidopsis tissues, the pool of tubulin protein is provided by the expression of multiple α-tubulin and β-tubulin genes. Previous evidence suggested that the TUA2 α-tubulin gene was expressed in all organs of mature plants. We now report a more detailed analysis of TUA2 expression during plant development. Chimeric genes containing TUA2 5′-flanking DNA fused to the β-glucuronidase (GUS) coding region were used to create transgenic Arabidopsis plants. Second-generation progeny of regenerated plants were analyzed by histochemical assay to localize GUS expression. GUS activity was seen throughout plant development and in nearly all tissues. The blue product of GUS activity accumulated to the highest levels in tissues with actively dividing and elongating cells. GUS activity was not detected in a few plant tissues, suggesting that, though widely expressed, the TUA2 promoter is not constitutively active.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027126
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  • 49
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    Construction of a Synechocystic PCC6803 mutant suitable for the study of variant hexadecameric ribulose bisphosphate carboxylase/oxygenase enzymes (1993)
    Springer
    Plant molecular biology 23 (1993), S. 465-476 
    Details
    ISSN: 1573-5028
    Keywords: carboxysomes ; cyanobacteria ; rbc genes ; Rubisco ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cyanobacterium Synechocystis PCC6803 was chosen as a target organism for construction of a suitable photosynthetic host to enable selection of variant plant-like ribulose bisphosphate carboxylase/oxygenase (Rubisco) enzymes. The DNA region containing the operon encoding Rubisco (rbc) was cloned, sequenced and used for the construction of a transformation vector bearing flanking sequences to the rbc genes. This vector was utilized for the construction of a cyanobacterial rbc null mutant in which the entire sequence comprising both rbc genes, was replaced by the Rhodospirillum rubrum rbcL gene linked to a chloramphenicol resistance gene. Chloramphenicol-resistant colonies, Syn6803†rbc, were detected within 8 days when grown under 5% CO2 in air. These transformants were unable to grow in air (0.03% CO2). Analysis of their genome and Rubisco protein confirmed the site of the mutation at the rbc locus, and indicated that the mutation had segregated throughout all of the chromosome copies, consequently producing only the bacterial type of the enzyme. In addition, no carboxysome structures could be detected in the new mutant. Successful restoration of the wild-type rbc locus, using vectors bearing the rbc operon flanked by additional sequences at both termini, could only be achieved upon incubating the transformed cells under 5% CO2 in air prior to their transferring to air. The yield of restored transformants was proportionally related to the length of those sequences flanking the rbc operon which participate in the homologous recombination. The Syn6803Δrbc mutant is amenable for the introduction of in vitro mutagenized rbc genes into the rbc locus, aiming at the genetic modification of the hexadecameric type Rubisco.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019295
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  • 50
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    Use of bar as a selectable marker gene and for the production of herbicide-resistant rice plants from protoplasts (1993)
    Springer
    Plant molecular biology 21 (1993), S. 871-884 
    Details
    ISSN: 1573-5028
    Keywords: bar ; herbicide resistance ; phosphinothricin acetyltransferase ; rice ; selectable marker ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have used the bar gene in combination with the herbicide Basta to select transformed rice (Oryza sativa L. cv. Radon) protoplasts for the production of herbicide-resistant rice plants. Protoplasts, obtained from regenerable suspension cultures established from immature embryo callus, were transformed using PEG-mediated DNA uptake. Transformed calli could be selected 2–4 weeks after placing the protoplast-derived calli on medium containing the selective agent, phosphinothricin (PPT), the active component of Basta. Calli resistant to PPT were capable of regenerating plants. Phosphinothricin acetyltransferase (PAT) assays confirmed the expression of the bar gene in plants obtained from PPT-resistant calli. The only exceptions were two plants obtained from the same callus that had multiple copies of the bar gene integrated into their genomes. The transgenic status of the plants was varified by Southern blot analysis. In our system, where the transformation was done via the protoplast method, there were very few escapes. The efficiency of co-transformation with a reporter gene gusA, was 30%. The To plants of Radon were self-fertile. Both the bar and gusA genes were transmitted to progeny as confirmed by Southern analysis. Both genes were expressed in T1 and T2 progenies. Enzyme analyses on T1 progeny plants also showed a gene dose response reflecting their homozygous and heterozygous status. The leaves of To plants and that of the progeny having the bar gene were resistant to application of Basta. Thus, the bar gene has proven to be a useful selectable and screenable marker for the transformation of rice plants and for the production of herbicide-resistant plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027118
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  • 51
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    Regeneration and somaclonal variation in apomictic Paspalum dilatatum Poir (1993)
    Springer
    Euphytica 67 (1993), S. 71-78 
    Details
    ISSN: 1573-5060
    Keywords: Paspalum dilatatum ; apomixis ; common dallisgrass ; plant regeneration ; somaclonal variation ; fertility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In an attempt to incorporate variation into a uniform obligate apomict, plants of apomictic common dallisgrass, Paspalum dilatatum Poir., were regenerated from callus derived from immature inflorescences. Plants developed through both organogenesis and embryogenesis. A total of 682 regenerants were produced and more than 400 were transplanted into a field nursery and screened for somaclonal variation. Eventually 20 regenerants were selected, increased, and planted into a replicated nursery along with normal common dallisgrass. The characteristics examined were maturity date, plant height, number of racemes per inflorescence, number of spikelets per raceme, pubescence, stigma and anther color, ergot resistance, seed germination, seed set, pollen stainability, method of reproduction, and chromosome number. There were differences among the regenerants and between them and common dallisgrass for all traits except chromosome number, stigma and anther color, and ergot resistance. One of the more important regenerants had significantly higher seed set than common dallisgrass. All regenerants reproduced by aposporous apomixis but some exhibited a high degree of abortion while others had more aposporous embryo sacs per ovule than common dallisgrass. These findings demonstrate that common dallisgrass can be regenerated through tissue culture and that somaclonal variation is expressed in some of the regenerants, even though some of the altered traits are deleterious.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00022727
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    The cell biology of plant transformation: Current state, problems, prospects and the implications for the plant breeding (1993)
    Springer
    Euphytica 71 (1993), S. 1-14 
    Details
    ISSN: 1573-5060
    Keywords: Agrobacterium tumefaciens ; biolistics ; co-suppression ; co-transformation ; electroporation ; epistasis ; gene silencing ; somaclonal variation ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The DNA delivery systems which are routinely used to introduce genes into crop plants are Agrobacterium tumefaciens, electroporation and particle bombardment. The differences and similarities between these different transformation techniques are outlined. The influence of the cell biological approach, and more specifically the impact of the state of the plant cell at the moment of transformation, on the genotype and phenotype of the regenerated transgenic plant is analysed. In this respect phenomena such as position effects, gene silencing, co-suppression, epistasis, co-transformation and somaclonal variation are discussed. The relevance of these factors for plant breeders is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023461
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  • 53
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    A study of some factors affectingAgrobacterium transformation and plant regeneration ofDendranthema grandiflora Tzvelev (syn.Chrysanthemum morifolium Ramat.) (1993)
    Springer
    Plant cell, tissue and organ culture 33 (1993), S. 171-180 
    Details
    ISSN: 1573-5044
    Keywords: Agrobacterium ; Dendranthema grandiflora ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In an attempt to develop a system for producing transformed plants from explants ofDendranthema grandiflora, the susceptibility of the cultivar Super White to various wild-type strains ofAgrobacterium tumefaciens andA. rhizogenes was investigated. Tumour formation was not a reliable indicator of the ability of a related disarmed strain to mediate transformation. Following inoculation of explants with disarmedAgrobacterium strains, a number of shoots developed on selective media. However, none of these shoots were transformed. By co-cultivating stem internode explants with a mixed inoculum of wild-type and disarmed strains, it was possible to obtain a callus stably transformed withAgrobacterium carrying a disarmed T-DNA. Histological analysis of explants revealed that shoot regeneration initially occurred from the cells of the epidermis and subsequently from the cortex. However, the cells which were susceptible to T-DNA transfer were confined to the vascular tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01983231
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  • 54
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    Fruit and vegetative characteristics of endosperm-derived kiwifruit (Actinidia chinensis F) plants (1993)
    Springer
    Euphytica 71 (1993), S. 57-62 
    Details
    ISSN: 1573-5060
    Keywords: Actinidia chinensis ; kiwifruit ; kiwi ; endosperm-derived plants ; field characteristics ; somaclonal variation ; in vitro ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Four hundred and thirty-eight endosperm-derived plants of kiwifruit (Actinidia chinensis) were observed. The plants were field planted in 1982 and all had flowered annually since 1986. A sample of these plants was assessed for leaf morphology, growth characteristics, flowering, sex expression, chromosome number, and fruit quality characteristics. The chromosome number of the endosperm plants varied from 58 to 146; most were aneuploid. A few triploid plants (2n=3x=87) were obtained; none of these were parthenocarpic. Segregation of sex expression was observed in progeny from one endosperm-derived callus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023467
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  • 55
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    Effects of growth regulators on callus cell growth, plant regeneration, and somaclonal variation of smooth bromegrass (Bromus inermis Leyss.) (1993)
    Springer
    Euphytica 69 (1993), S. 77-82 
    Details
    ISSN: 1573-5060
    Keywords: Bromus inermis ; callus culture ; growth regulators ; smooth bromegrass ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Immature inflorescences of smooth bromegrass were cultured on MS agar media supplemented with varying combinations of 2,4-D and kinetin. Callus was initiated from segments of young inflorescences on each medium. All of the calli were subcultured monthly for 5–6 times and transferred onto hormone-free MS medium for plant regeneration. Addition of kinetin to the basal medium stimulated shoot initiation in the callus cultures. Plantlets were regenerated only from calli grown on media containing 2 and 6 mg I-1 2,4-D with a supplement of 0.2 mg I-1 kinetin. No albino plantlets were produced. Morphological characteristics and dry matter yield of ten somaclones and the parental plant (SBG7) were studied in the greenhouse in a randomized complete block experiment with five replications. There was significant variation (P〉0.01) among genotypes for all morphological characteristics studied. Although all somaclone heights and leaf widths were lower than those of the parental plant, the somaclone F9A, F10A, and F10B had larger tiller numbers, and leaf/stem ratio by dry weight than the parental plant. Only somaclone F9B gave higher specific leaf area and leaf area ratio than the parental plant. Almost all somaclones had the same leaf length, total dry weight, and specific leaf weight as the parental plant. The variation found in somaclones should permit selection for desirable agronomic traits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021728
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  • 56
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    Localization of light-inducible and tissue-specific regions of the spinach ribulose bisphosphate carboxylase/oxygenase (rubisco) activase promoter in transgenic tobacco plants (1993)
    Springer
    Plant molecular biology 23 (1993), S. 1129-1138 
    Details
    ISSN: 1573-5028
    Keywords: cis elements ; light regulation ; Rca promoter ; rubisco activase ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Deletions in the spinach rubisco activase (Rca) promoter in transgenic tobacco were analyzed to define the regions necessary for conferring light-inducible and tissue-specific expression. Transgenic plants were constructed with Bal 31 deletions of the Rca promoter fused to the coding region of the bacterial reporter gene β-glucuronidase (GUS). Analysis of the Rca deletion mutants localized the region conferring normal expression downstream from −294 relative to the Rca transcription start site. A second set of transgenic plants containing the cauliflower mosaic virus (CaMV) 35S enhancer fused to the 3′ end of the Rca/GUS constructs demonstrated the presence of a light-responsive element between −150 and −78 active in leaves. Regions 10 bp long within the light-responsive region, which included putative G box and GT elements, were removed by recombinant polymerase chain reaction. Deletion of the G box element resulted in a loss of gene expression in the leaves of transgenic tobacco, while deletion of the GT motif caused a 10–100-fold increase in expression in roots. However, site-directed mutagenesis of the GT motif resulted in expression patterns identical to the normal promoter. These experiments demonstrated that light-inducible and tissue-specific expression of the Rca promoter involves multiple cis elements proximal to the transcription start site, and that interactions between these elements are essential for regulating expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042347
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  • 57
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    Treatment of Agrobacterium or leaf disks with 5-azacytidine increases transgene expression in tobacco (1993)
    Springer
    Plant molecular biology 21 (1993), S. 429-435 
    Details
    ISSN: 1573-5028
    Keywords: azacytidine ; DNA methylation ; gene expression ; inactivation ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have studied the effect of the demethylating agent azacytidine (azaC) on expression of a β-glucuronidase (GUS) gene transferred to tobacco leaf disks by Agrobacterium-mediated transformation. In a system where no selection was performed, where shoot formation was partially repressed, and where Agrobacterium does not express the GUS gene, we were able to follow the early events of transient and stable expression. Two days after inoculation, 8% of the cells expressed GUS but this proportion rapidly decreased to near zero in the following week. Treatment of leaf disks with azaC just after transformation retarded this inactivation to some extent, while treatment of Agrobacterium prior to transformation increased the frequency of transient expression. Three weeks after inoculation the number of GUS-expressing cells increased 4- to 6-fold in the leaf disks treated with azaC and in the leaf disks transformed with azaC-treated bacteria, while the control remained low. These data suggest that DNA methylation is involved in transgene inactivation and that a large number of silent but potentially active transgenes become integrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028801
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  • 58
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    Activity of a chimeric promoter with the doubled CaMV 35S enhancer element in protoplast-derived cells and transgenic plants in maize (1993)
    Springer
    Plant molecular biology 21 (1993), S. 415-428 
    Details
    ISSN: 1573-5028
    Keywords: Zea mays L. ; protoplast ; DNA uptake ; transformation ; β-glucuronidase ; promoter ; α-amylase gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A reproducible and efficient transformation system has been developed for maize that is based on direct DNA uptake into embryogenic protoplasts and regeneration of fertile plants from protoplast-derived transgenic callus tissues. Plasmid DNA, containing the β-glucuronidase (GUS) gene, under the control of the doubled enhancer element (the −208 to −46 bp upstream fragment) from CaMV 35S promoter, linked to the truncated (up to −389 bp from ATG) promoter of wheat, α-amylase gene was introduced into protoplasts from suspension culture of HE/89 genotype. The constructed transformation vectors carried either the neomycin phosphotransferase (NPTII) or phosphinothricin acetyltransferase (PAT) gene as selective marker. The applied DNA uptake protocol has resulted at least in 10–20 resistant calli, or GUS-expressing colonies after treatment of 106 protoplasts. Vital GUS staining of microcalli has made possible the shoot regeneration from the GUS-stained tissues. 80–90% of kanamycin or PPT resistant calli showed GUS activity, and transgenic plants were regenerated from more than 140 clones. Both Southern hybridization and PCR analysis showed the presence of introduced foreign genes in the genomic DNA of the transformants. The chimeric promoter, composed of a tissue specific monocot promoter, and the viral enhancer element specified similar expression pattern in maize plants, as it was determined by the full CaMV 35S promoter in dicot and other monocot plants. The highest GUS specific activity was found in older leaves with progressively less activity in young leaves, stem and root. Histochemical localization of GUS revealed promoter function in leaf epidermis, mesophyll and vascular bundles, in the cortex and vascular cylinder of the root. In roots, the meristematic tip region and vascular tissues stained intensively. Selected transformants were grown up to maturity, and second-generation seedlings with segregation for GUS activity were obtained after outcrossing. The GUS-expressing segregants carried also the NPTII gene as shown by Southern hybridization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028800
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    Transient and stable expression ofgusA fusions with rice genes in rice, barley and perennial ryegrass (1993)
    Springer
    Plant molecular biology 22 (1993), S. 1101-1127 
    Details
    ISSN: 1573-5028
    Keywords: transformation ; promoters ; introns ; gene expression ; Oryza sativa ; Hordeum vulgare ; Lolium perenne
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcriptional and translational fusions were made between the reading frame coding for β-D-glucuronidase and sequences of either a constitutively expressed rice gene (GOS2) involved in initiation of translation or a light-inducible rice gene (GOS5). The transient expression of the fusions was studied via particle bombardment of seedling tissues of rice, perennial ryegrass and barley. Furthermore, the results of transient and stable expression were compared for cell suspensions of four rice varieties, one barley variety and one perennial ryegrass variety. TheGOS2-gusA fusions were active in all three monocots studied. Best results were obtained for a construct having both a transcriptional and a translational fusion as well as intron and exon sequences (PORCEHyg). The level of GUS activity was in the range of activities as obtained by the 35S CaMV promoter transcriptionally fused togusA. ThegusA fusion with the light-inducible gene (GOS5) was active in green seedling tissues of all monocots studied. Also a weak expression compared to theGOS2 constructs was found in stably transformed rice callus. ThegusA fusions with the mannopine synthase promoters 1′ and 2′ of the TR-DNA were transiently expressed at lower levels in cell suspensions than PORCEHyg. For stably transformed rice callus the expression of theGOS2-gusA fusion often decreased during prolonged subculture. This decrease in GUS activity and the various GUS-staining phenotypes of transgenic calli are explained by the presence of different cell types in the suspensions used and in the calli. It is presumed that the nature of the cells and their relative contribution in the calli change drastically upon further subculture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028980
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  • 60
    Electronic Resource
    Electronic Resource
    Transient and stable expression of gusA fusions with rice genes in rice, barley and perennial ryegrass (1993)
    Springer
    Plant molecular biology 23 (1993), S. 643-669 
    Details
    ISSN: 1573-5028
    Keywords: transformation ; promoters ; introns ; gene expression ; Oryza sativa ; Hordeum vulgare ; Lolium perenne
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcriptional and translational fusions were made between the reading frame coding for β-D-glucuronidase and sequences of either a constitutively expressed rice gene (GOS2) involved in initiation of translation or a light-inducible rice gene (GOS5). The transient expression of the fusions was studied via particle bombardment of seedling tissues of rice, perennial ryegrass and barley. Furthermore, the results of transient and stable expression were compared for cell suspensions of four rice varieties, one barley variety and one perennial ryegrass variety. The GOS2-gusA fusions were active in all three monocots studied. Best results were obtained for a construct having both a transcriptional and a translational fusion as well as intron and exon sequences (PORCEHyg). The level of GUS activity was in the range of activities as obtained by the 35S CaMV promoter transcriptionally fused to gusA. The gusA fusion with the light-inducible gene (GOS5) was active in green seedling tissues of all monocots studied. Also a weak expression compared to the GOS2 constructs was found in stably transformed rice callus. The gusA fusions with the mannopine synthase promoters 1′ and 2′ of the TR-DNA were transiently expressed at lower levels in cell suspensions than PORCEHyg. For stably transformed rice callus the expression of the GOS2-gusA fusion often decreased during prolonged subculture. This decrease in GUS activity and the various GUS-staining phenotypes of transgenic calli are explained by the presence of different cell types in the suspensions used and in the calli. It is presumed that the nature of the cells and their relative contribution in the calli change drastically upon further subculture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021522
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  • 61
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    Electronic Resource
    Stable transformation of peanut callus viaAgrobacterium-mediated DNA transfer (1993)
    Springer
    Transgenic research 2 (1993), S. 321-324 
    Details
    ISSN: 1573-9368
    Keywords: Peanut ; Arachis hypogaea ; transformation ; callus ; Agrobacterium tumefaciens ; peanut stripe virus coat protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transformed callus was produced from peanut (Arachis hypogaea L. cv. Okrun) hypocotyl explants after four days of co-cultivation withAgrobacterium tumefaciens strains EHA101, LBA4404 or ASE1 carrying the binary vector pKYLX71GUS on a defined medium followed by selection with kanamycin (200 mg l−1). Transformed calluses were cultured as independent cell lines potentially derived from a single transformation event. Stable integration and expression of foreign gene(s) in the callus was confirmed by Southern and western blot analyses and enzyme assays. A few cell lines showed a single insert of the foreign gene. Using the above protocol, transformed peanut callus expressing the peanut stripe virus coat protein gene was obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01976172
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  • 62
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    Electronic Resource
    Introduction of hygromycin resistance inLotus spp. throughAgrobacterium rhizogenes transformation (1993)
    Springer
    Transgenic research 2 (1993), S. 330-335 
    Details
    ISSN: 1573-9368
    Keywords: Lotus ; Agrobacterium rhizogenes ; transformation ; hygromycin resistance ; tannins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The speciesLotus corniculatus andL. tenuis were transformed with anAgrobacterium rhizogenes binary vector, conferring resistance to the antibiotic hygromycin. Transgenic plants recovered from both species were tested for the ability of leaf-derived calluses to grow in a hygromycin-supplemented medium. Molecular analysis showed the integration of the Ri T-DNA and of the gene for hygromycin resistance, with a high frequency of co-transformation. Progeny analysis of the hygromycin resistance indicated this to be a single Mendelian trait in test plants. The transformed plants will be utilized in somatic hybridization experiments with lucerne for producing non-bloating genotypes with condensed tannins in leaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01976174
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  • 63
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    Interaction of the neu/p185 and EGF receptor tyrosine kinases: Implications for cellular transformation and tumor therapy (1993)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 53 (1993), S. 61-73 
    Details
    ISSN: 0730-2312
    Keywords: neu/p185 protein ; c-erbB-2 ; epidermal growth factor receptor ; transformation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Growth factor receptors such as the epidermal growth factor receptor (EGFR) and the p185c-neu protein serve vital roles in the transduction of differentiation, developmental, or mitogenic signaling within normal cells. Two methods of analysis suggest that the inappropriately high expression of either protein tyrosine kinase promotes malignant transformation. First, data from in vitro experiments indicate that overexpression of either EGFR or p185c-neu (or the human homolog c-erbB-2) transforms cell-lines. Second, analysis of primary tumors and tumor cell-lines derived from many epithelial tissues (breast, stomach, ovary, and pancreas) show growth factor receptor gene amplification and elevated protein levels. The physical and functional interaction of p185c-neu and EGFR leads to the formation of a highly active, heterodimeric tyrosine kinase complex which synergistically activates cellular transformation. Anti-receptor antibodies have shown potential utility for the down modulation of these cell-surface proteins and suppression of the malignant phenotype. Design of organic antibody “mimetics” based on the structure of antireceptor antibodies may provide useful therapies and biological reagents to affect growth factor receptor function.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240530108
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  • 64
    Electronic Resource
    Electronic Resource
    Transformation of vitis tissue by different strains of Agrobacterium tumefaciens containing the T-6b gene (1992)
    Springer
    Plant cell reports 11 (1992), S. 192-195 
    Details
    ISSN: 1432-203X
    Keywords: Grapevine ; Agrobacterium tumefaciens ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Stem pieces and leaf disks of Vitis spp. were cocultured with Agrobacterium tumefaciens strains carrying the UidA (ß-glucuronidase = GUS) gene. The transformation efficiency was highly increased by using a modified T-6b gene (a gene from pTiTm4) which interferes with normal growth and allows regeneration of normal Nicotiana rustica plants (Tinland 1990). The strains first tested on stem segments were subsequently tested in a leaf explant system. On leaves the transformation efficiency of the strains was much lower than with stems. Both the T-6b gene and the hsp 70-T-6b gene (a modified T-6b gene under the control of a heat shock promoter) allowed the initiation of GUS-positive buds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232531
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  • 65
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    Electronic Resource
    Transformation of rapid cycling cabbage (Brassica oleracea var. capitata) with Agrobacterium rhizogenes (1992)
    Springer
    Plant cell reports 11 (1992), S. 334-338 
    Details
    ISSN: 1432-203X
    Keywords: Brassica oleracea ; rapid cycling cabbage ; transformation ; Agrobacterium rhizogenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Genetically transformed cabbage (Brassica oleracea var. capitata) roots were obtained after inoculation with two engineered Agrobacterium rhizogenes strains, each harbouring a plant selectable marker gene in their T-DNA. Axenic root clones resistant to kanamycin or hygromycin B were established, most of which did not exhibit the phenotypic characteristics of Ri-transformed roots. Shoot regeneration was induced from roots after treatment with 2,4-dichlorophenoxyacetic acid (2,4-D). The resulting plants exhibited various phenotypes: some looked normal, while others showed the transformed phenotype observed in other species. Direct evidence for genetic transformation was obtained by molecular hybridization. The trait was transmitted to the progeny. Transformed cabbage plants can be obtained within 6 months using this approach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233360
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  • 66
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    Stably transformed herbicide resistant callus of sugarcane via microprojectile bombardment of cell suspension cultures and electroporation of protoplasts (1992)
    Springer
    Plant cell reports 11 (1992), S. 494-498 
    Details
    ISSN: 1432-203X
    Keywords: Sugarcane ; cell suspension ; protoplast ; microprojectile bombardment ; electroporation ; GUS ; bar ; PAT ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stably transformed callus of a hybrid sugarcane cultivar (Saccharum species hybrid, CP72-1210) was achieved following high velocity microprojectile bombardment of suspension culture cells, and electroporation of protoplasts. A three-day old cell suspension culture (SC88) was bombarded with gold particles coated with pBARGUS plasmid DNA containing the ß-glucuronidase (GUS) reporter gene and the bar selectable gene that confers resistance to the herbicide basta. The pBARGUS plasmid was also electroporated into the protoplasts of another cell line (SCPP). Colonies resistant to basta were recovered from both sources. Stable integration of the bar gene in the resistant cell lines was confirmed by Southern analysis. In addition, phosphinothricin acetyltransf erase (PAT) activity was also demonstrated in the transformed cell lines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236264
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  • 67
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    Transformation of Solanum integrifolium poir via Agrobacterium tumefaciens: Plant regeneration and progeny analysis (1992)
    Springer
    Plant cell reports 11 (1992), S. 11-15 
    Details
    ISSN: 1432-203X
    Keywords: Agrobacterium tumefaciens ; Solanum integrifolium ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The wild species Solanum integrifolium represents a source of pest and disease resistance genes for breeding strategies of the cultivated species Solanum melongena. Somatic hybridization via protoplast fusion between the two species may provide a valuable tool for transferring polygenic traits into the cultivated species. The availability of S.integrifolium cells carrying dominant selectable markers would facilitate the heterokaryon rescue. An appropriate methodology for in vitro culture and plant regeneration from leaf explants of S.integrifolium is reported. Efficient leaf-disk transformation via co-cultivation with Agrobacterium tumefaciens led to the regeneration of transformed plants carrying the reporter genes GUS and NPT-II. Transformed individuals were obtained through selection on kanamycin-containing medium. Stable genetic transformation was assessed by histochemical and enzymatic assays for GUS and NPT-II activity, by the ability of leaf disks to initiate callus on Km-containing medium, Southern blot analyses of the regenerated plants, and genetic analysis of their progenies. Selfed-seed progeny of individual transformed plants segregated seedlings capable to root and grow in selective condition, while untransformed progeny did not. Genetic analyses of progeny behaviour showed that the reporter gene NPT-II segregated as single as well as two independent Mendelian factors. In two cases an excess of kanamycin-sensitive seedlings was obtained, not fitting into any genetic hypothesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231831
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  • 68
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    Electronic Resource
    Plasmid mediated metal and antibiotic resistance in marinePseudomonas (1992)
    Springer
    BioMetals 5 (1992), S. 73-80 
    Details
    ISSN: 1572-8773
    Keywords: mercury ; arsenic ; cadmium ; plasmid ; restriction analysis ; curing ; conjugation ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Pseudomonas sp isolated from the Bay of Bengal (Madras coast) contained a single large plasmid (pMR1) of 146 kb. Plasmid curing was not successful with mitomycin C, sodium dodecyl sulfate, acridine orange, nalidixic acid or heat. Transfer of mercury resistance from marinePseudomonas toEscherichia coli occurred during mixed culture incubation in liquid broth at 10−4 to 10−5 ml−1. However, transconjugants lacked the plasmid pMR1 and lost their ability to resist mercury. Transformation of pMR1 intoE. coli competent cells was successful; however, the efficiency of transformation (1.49×102 Hgr transformants μg−1 pMR1 DNA) was low.E. coli transformants containing the plasmid pMR1 conferred inducible resistance to mercury, arsenic and cadmium compounds similar to the parental strain, but with increased expression. The mercury resistant transformants exhibited mercury volatilization activity. A correlation existed between metal and antibiotic resistance in the plasmid pMR1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01062217
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  • 69
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    Variants of carnation (Dianthus caryophyllus L.) obtained by organogenesis from irradiated petals (1992)
    Springer
    Plant cell, tissue and organ culture 29 (1992), S. 37-42 
    Details
    ISSN: 1573-5044
    Keywords: mutagenesis ; petal culture ; regeneration ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To obtain carnation variants differing from those produced by organogenesis alone, in vitro petal cultures were subjected to gamma irradiation. Histological analysis revealed the surface origin of buds and the different steps in meristem formation. A dose of 40 Gy administered on the fourth day of culture produced variants of horticultural interest in ‘Niky’. This period corresponded to dedifferentiation of cells that subsequently developed into bubs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00036144
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  • 70
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    A statistical comparison of various factors on embryogenic proliferation, morphogenesis and regeneration in Lolium temulentum cell suspension colonies (1992)
    Springer
    Plant cell, tissue and organ culture 30 (1992), S. 15-29 
    Details
    ISSN: 1573-5044
    Keywords: cell suspension ; embyrogenesis ; Lolium ; regeneration ; somaclonal variation ; statistical analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell suspension colonies from four embryogenic Lolium temulentum lines were selected and plated individually in 25 embryoid maturation treatments which varied in various factors reported to stimulate embryogenesis or improve regeneration. Using a numerical scoring system to compare the cultures against a control, treatments were identified which increased growth, suppressed morphogenesis or encouraged premature shoot formation. No treatment significantly improved the proportion of colonies with globular or mature embryoids, but some prevented maturation and increased the proportion with translucent embryogenic proliferation. Other treatments accelerated maturation causing increased de-differentiation of embryogenic tissues. These treatments also tended to discourage the differentiation of discreet embryoids. Colonies were later transferred en masse to a regeneration medium and scored using another numerical system. Embryoid maturation conditions were then identified which increased or suppressed subsequent shoot regeneration. The two scoring systems enabled cultures of the four lines to be characterised in detail and identified somatic variation in embryogenic development, morphogenesis and de-differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00039997
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  • 71
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    Hexokinase receptors: Preferential enzyme binding in normal cells to nonmitochondrial sites and in transformed cells to mitochondrial sites (1992)
    Springer
    Journal of bioenergetics and biomembranes 24 (1992), S. 47-53 
    Details
    ISSN: 1573-6881
    Keywords: Mitochondria ; hexokinase ; normal and tumor cells ; enzyme localization ; subcellular fractionation ; receptor for binding ; monoamine oxidase ; NADPH-cytochromec reductase ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Hexokinase plays an important role in normal glucose-utilizing tissues like brain and kidney, and an even more important role in highly malignant cancer cells where it is markedly overexpressed. In both cell types, normal and transformed, a significant portion of the total hexokinase activity is bound to particulate material that sediments upon differential centrifugation with the crude “mitochondrial” fraction. In the case of brain, particulate binding may constitute most of the total hexokinase activity of the cell, and in highly malignant tumor cells as much as 80 percent of the total. When a variety of techniques are rigorously applied to better define the particulate location of hexokinase within the crude “mitochondrial fraction,” a striking difference is observed between the distribution of hexokinase in normal and transformed cells. Significantly, particulate hexokinase found in rat brain, kidney, or liver consistently distributes with nonmitochondrial membrane markers whereas the particulate hexokinase of highly glycolytic hepatoma cells distributes with outer mitochondrial membrane markers. These studies indicate that within normal tissues hexokinase binds preferentially to non-mitochondrial receptor sites but upon transformation of such cells to yield poorly differentiated, highly malignant tumors, the overexpressed enzyme binds preferentially to outer mitochondrial membrane receptors. These studies, taken together with the well-known observation that, once solubilized, the particulate hexokinase from a normal tissue can bind to isolated mitochondria, are consistent with the presence in normal tissues of at least two different types of particulate receptors for hexokinase with different subcellular locations. A model which explains this unique transformation-dependent shift in the intracellular location of hexokinase is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00769530
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  • 72
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    Nutrient transformation in soil due to addition of organic manure and growing crops (1992)
    Springer
    Nutrient cycling in agroecosystems 32 (1992), S. 313-319 
    Details
    ISSN: 1573-0867
    Keywords: Maize-mustard crop sequence ; ‘methanised’ FYM-bioslurry ; inter-relationships ; zinc fractions ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Organic matter is the major source of zinc in soil. The availability of this nutrient is dependent on the release from organic matter through mineralization and reaction with soil particles. Addition of bioslurry, containing 70 mg Zn kg−1 will influence availability of Zn through its effect on transformation reaction in soil. The present study was conducted to determine the distribution of major chemical forms of Zn in an alluvial soil, to understand the changes in zinc fractions due to bioslurry application and cropping and to find out the inter-relationships and equilibria between the fractions. Soil solution + exchangeable Zn (Zn-CA), specifically sorbed Zn by inorganic sites (Zn-ACC), specifically sorbed Zn by organic sites (Zn-PYR), Zn occluded by free oxides (Zn-OX), and residual zinc (Zn-RES) constituted 0.3, 4.5, 16.6, 16.3 and 57.3 percent, respectively of the total Zn content (Zn-TOT). Application of 13.32 t ha−1 bioslurry increased Zn content in Zn-CA, Zn-PYR and Zn-RES by 72.7, 93.2 and 36.4 percent, respectively over control. Zn occluded by free oxides (Zn-OX) was found released by the dissolution action of organic compounds present in bioslurry and the amount of Zn so released was transformed to Zn-RES, Zn-CA and Zn-DTPA. Growing crops increased Zn content in Zn-RES fraction only. Linear positive relationships between Zn-CA, Zn-PYR, Zn-RES and DTPA-Zn and bioslurry levels marked the significance of bioslurry in stabilising the status of these fractions. Path coefficient analysis and intercorrelation studies indicated the existence of equilibrium between different Zn fractions in soils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01050368
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  • 73
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    Genetics of antagonistic action and drug resistance inLactobacillus acidophilus (1992)
    Springer
    World journal of microbiology and biotechnology 8 (1992), S. 92-97 
    Details
    ISSN: 1573-0972
    Keywords: Bacteriocin ; conjugation ; electroporation ; Lactobacillus acidophilus ; protoplast fusion ; plasmids ; transduction ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Lactobacillus acidophilus has been recommended as a dietary adjunct because of its antagonistic action toward intestinal pathogens and anti-carcinogenic and hypocholesterolemic activities. ManyL. acidophilus strains harbour plasmids and such strains generally produce bacteriocin(s). Resistance to antibiotics has also been shown to be linked with plasmids. Gene transfer and cloning systems are being developed forL. acidophilus which should permit the rapid genetic characterization of desired species and their modification to obtain predetermined traits. Drug resistance determinants and production of antibiotic-like substances may serve as suitable markers for the study and development of these genetic systems. Recent developments in gene transfer systems have been reviewed here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01195823
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  • 74
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    Loss of resistance to Colletotrichum trifolii in in vitro regenerated alfalfa (1992)
    Springer
    Plant cell, tissue and organ culture 28 (1992), S. 207-213 
    Details
    ISSN: 1573-5044
    Keywords: anthracnose ; disease resistance ; Medicago sativa ; somaclonal variation ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Alfalfa plants were regenerated from callus cultures of three source plants that differed in resistance to anthracnose, caused by Colletotrichum trifolii. All regenerant plants were evaluated for variation in resistance to disease caused by races 1 and 2 of the pathogen. Of eighty-two plants that were regenerated and evaluated, no plants responded differently to inoculation with race 1 of C. trifolii, but two plants (2.4%) differed in resistance when inoculated with race 2. The source plant of these regenerants was resistant to races 1 and 2 of the pathogen but the regenerants were resistant to race 1 and susceptible to race 2. No variants to race 1 were detected. The susceptible response of the variant plants to race 2 was confirmed by cytological analysis and was consistent with the response of nonregenerant susceptible plants. These plants represent a near-isogenic plant model for studying the molecular biology of resistance and susceptibility to anthracnose of alfalfa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00055519
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  • 75
    Electronic Resource
    Electronic Resource
    Site-specific oligodeoxynucleotide binding to maize Adh1 gene promoter represses Adh1-GUS gene expression in vivo (1992)
    Springer
    Plant molecular biology 19 (1992), S. 715-723 
    Details
    ISSN: 1573-5028
    Keywords: DNase I footprinting ; β-glucuronidase (GUS) ; H-DNA ; transformation ; triple helix
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract There is a 36 bp tract of extreme homopurine/homopyrimidine (PuPy) asymmetry in the maize Adh1 gene promoter (from −44 to −79) that is S1-hypersensitive in plasmids under supercoil tension. Oligodeoxynucleotides corresponding to the PuPy tract were designed to examine the secondary structure of the region and address the possible role of the tract in gene regulation. On the basis of oligodeoxynucleotide band-shift and DNase I footprinting analyses, it was concluded that the homopyrimidine oligodeoxynucleotide can form a triple helix with the duplex PuPy tract in vitro. Transient assays in protoplasts, suspension cells, and seedling roots show that the homopyrimidine oligodeoxynucleotide is also capable of repressing Adh1-GUS gene expression during co-transformation, presumably by the formation of a triple helix with the PuPy tract in vivo. The complementary homopurine oligodeoxynucleotide would not form a triple helix in vitro, nor would it repress Adh1-GUS in vivo. We propose that triple helix formation is a potential regulatory phenomenon in vivo, and that an intraregion triple helix could occur within the Adh1 promoter via the formation of H-DNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027068
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  • 76
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    Analysis of the region in between two closely linked patatin genes: class II promoter activity in tuber, root and leaf (1992)
    Springer
    Plant molecular biology 20 (1992), S. 683-694 
    Details
    ISSN: 1573-5028
    Keywords: patatin class II gene ; Solanum tuberosum ; transformation ; transgenic potato ; tuber-specific gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From a potato genomic library a phage lambda clone was isolated that carried nucleotide sequences of two patatin genes, thus demonstrating a close physical linkage between these two members of the patatin gene family. Sequence and restriction analysis showed the genes to be oriented in tandem. The more upstream gene was a pseudogene truncated at the 3′ end, whereas the downstream gene was a class II patatin gene. In addition to a 208 bp fragment also present in patatin class I promoters, the region in between both genes contained various direct repeats also found in other patatin genes. To study the promoter activity of this intergenic region, a 2.78 kb fragment was transcriptionally fused to the β-glucuronidase gene and reintroduced into potato cultivar Bintje. Histochemical analysis revealed expression in the outermost layer of cells of the cortex, in the tuber phellogen, in or around the root vascular system, and also in the abaxial phloem layer of the vascular bundle in leaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046453
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    Transformation and inheritance of a hygromycin phosphotransferase gene in maize plants (1992)
    Springer
    Plant molecular biology 18 (1992), S. 189-200 
    Details
    ISSN: 1573-5028
    Keywords: hygromycin ; inheritance ; maize ; tissue culture ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Embryogenic maize (Zea mays L.) callus cultures were transformed by microprojectile bombardment with a chimeric hygromycin phosphotransferase (HPT) gene and three transformed lines were obtained by selecting for hygromycin resistance. All lines contained one or a few copies of the intact HPT coding sequence. Fertile, transgenic plants were regenerated and the transmission of the chimeric gene was demonstrated through two complete generations. One line inherited the gene in the manner expected for a single, dominant locus, whereas two did not.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034948
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  • 78
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    Electronic Resource
    Segregation of transgenes in maize (1992)
    Springer
    Plant molecular biology 18 (1992), S. 201-210 
    Details
    ISSN: 1573-5028
    Keywords: maize ; transformation ; inheritance ; phosphinothricin acetyltransferase ; cotransformation ; microprojectile bombardment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Progeny recovered from backcrossed transgenic maize tissue culture regenerants (R0) were analyzed to determine the segregation, expression, and stability of the introduced genes. Transgenic A188×B73 R0 plants (regenerated from embryogenic suspension culture cells transformed by microprojectile bombardment; see [9]) were pollinated with nontransformed B73 pollen. Inheritance of a selectable marker gene, bar, and a nonselectable marker gene, uidA, was analyzed in progeny (R1) representing four independent transformation events. Activity of the bar gene product, phosphinothricin acetyltransferase (PAT), was assessed in plants comprising the four R1 populations. The number of R1 plants containing PAT activity per total number of R1 plants recovered for each population was 2/7, 19/34, 3/14 and 73/73. Molecular analysis confirmed the segregation of bar in three R1 populations and the lack of segregation in one R1 population. Cosegregation analysis indicated genetic linkage of bar and uidA in all four R1 populations. Analysis of numerous R2 plants derived from crossing transformed R1 plants with nontransformed inbreds revealed 1:1 segregation of PAT activity in three of four lines, including the line that failed to segregate in the R1 generation. Integrated copies of bar in one line appeared to be unstable or poorly transmitted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034949
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  • 79
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    Electronic Resource
    Plant transformation: a simple particle bombardment device based on flowing helium (1992)
    Springer
    Plant molecular biology 18 (1992), S. 835-839 
    Details
    ISSN: 1573-5028
    Keywords: transformation ; particle gun ; soybean ; GUS gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We observed that flowing helium at moderate pressures accelerated DNA-coated microprojectiles to velocities suitable for penetration of cells in intact plant tissues. The flowing helium principle permitted the construction of a simple and inexpensive transformation device that was easier to use than those previously described. This device provided efficient transformation of cells in soybean seedlings and other plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020031
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  • 80
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    Electronic Resource
    Regulation of lysine synthesis in transgenic potato plants expressing a bacterial dihydrodipicolinate synthase in their chloroplasts (1992)
    Springer
    Plant molecular biology 19 (1992), S. 815-823 
    Details
    ISSN: 1573-5028
    Keywords: dihydrodipicolinate synthase ; lysine overproduction ; potato ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The essential amino acid lysine is synthesized in higher plants by a complex pathway that is predominantly regulated by feedback inhibition of two enzymes, namely aspartate kinase (AK) and dihydrodipicolinate synthase (DHPS). Although DHPS is thought to play a major role in this regulation, the relative importance of AK is not known. In order to study this regulation, we have expressed in the chloroplasts of transgenic potato plants a DHPS derived from Escherichia coli at a level 50-fold above the endogenous DHPS. The bacterial enzyme is much less sensitive to lysine inhibition than its potato counterpart. DHPS activity in leaves, roots and tubers of the transgenic plants was considerably higher and more resistant to lysine inhibition than in control untransformed plants. Furthermore, this activity was accompanied by a significant increase in level of free lysine in all three tissues. Yet, the extent of lysine overproduction in potato leaves was significantly lower than that previously reported in leaves of transgenic plants expressing the same bacterial enzyme, suggesting that in potato, AK may also play a major regulatory role in lysine biosynthesis. Indeed, the elevated level of free lysine in the transgenic potato plants was shown to inhibit the lysine-sensitive AK activity in vivo. Our results support previous reports showing that DHPS is the major rate-limiting enzyme for lysine synthesis in higher plants, but they suggest that additional plant-specific regulatory factors are also involved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027077
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  • 81
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    Electronic Resource
    Somaclonal variation in plant adaptation to acid soil in the tropical forage legume Stylosanthes guianensis (1992)
    Springer
    Plant and soil 146 (1992), S. 21-30 
    Details
    ISSN: 1573-5036
    Keywords: biomass partitioning ; nutrient uptake ; plant adaptation ; soil acidity ; somaclonal variation ; Stylosanthes guianensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Somaclonal variation offers the possibility to obtain changes in one or a few characters of an otherwise outstanding cultivar without altering the remaining, and often unique, part of the genotype. It has been shown to be heritable for some species. A check line of Stylosanthes guianensis (Aubl.) Sw., CIAT 2243 and 14 somaclones in the R4 generation, selected after three generations from the original 114 plants regenerated from callus cultures, were used in a glasshouse trial. The main objective of the study was to evaluate the physiological basis of the differences in agronomic performance of certain somaclones over the check genotype when grown in a sandy loam acid soil at low or high fertility level. Measurements at the time of harvest (170 days of plant age) included dry matter distribution between shoot and roots, leaf area production, nutrient levels in soil and plant parts, and uptake of nutrients from soil. Somaclones differed with the check genotype in terms of (i) partitioning of fixed carbon between the shoot and roots; (ii) root biomass production and (iii) uptake of nitrogen and phosphorus. Positive relationships were found between total nitrogen uptake and total biomass, and total phosphorus uptake and total biomass, and total phosphorus uptake and total nitrogen uptake. The results of this study provide an insight into the potential use of somaclonal variation for the improvement of plant adaptation to acid soil conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00011991
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  • 82
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    Microprojectile bombardment of plant tissues increases transformation frequency by Agrobacterium tumefaciens (1992)
    Springer
    Plant molecular biology 18 (1992), S. 301-313 
    Details
    ISSN: 1573-5028
    Keywords: Agrobacterium tumefaciens ; β-glucuronidase ; meristem ; microprojectile bombardment ; neomycin phosphotransferase ; sunflower ; tobacco ; transformation ; wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bombardment of plant tissues with microprojectiles in an effective method of wounding to promote Agrobacterium-mediated transformation. Tobacco cv. Xanthi leaves and sunflower apical meristems were wounded by microprojectile bombardment prior to application of Agrobacterium tumefaciens strains containing genes within the T-DNA encoding GUS or NPTII. Stable kanamycin-resistant tobacco transformants were obtained using an NPTII construct from particle/plasmid, particle-wounded/Agrobacterium-treated or scalpel-wounded/Agrobacterium-treated potato leaves. Those leaves bombarded with particles suspended in TE buffer prior to Agrobacterium treatment produced at least 100 times more kanamycin-resistant colonies than leaves treated by the standard particle gun transformation protocol. In addition, large sectors of GUS expression, indicative of meristem cell transformation, were observed in plants recovered from sunflower apical explants only when the meristems were wounded first by particle bombardment prior to Agrobacterium treatment. Similar results in two different tissue types suggest that (1) particles may be used as a wounding mechanism to enhance Agrobacterium transformation frequencies, and (2) Agrobacterium mediation of stable transformation is more efficient than the analogous particle/plasmid protocol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034957
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  • 83
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    Is somaclonal variation a reliable tool for spring wheat improvement? (1992)
    Springer
    Euphytica 60 (1992), S. 221-228 
    Details
    ISSN: 1573-5060
    Keywords: agronomic performance ; somaclonal variation ; tissue culture ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Seed progeny of tissue culture regenerants of a spring wheat (Triticum aestivum L. cv. HY320) was evaluated for key agronomic traits for three years under field conditions. Initially, 27 regenerant families were tested in hill plots. Among-family and within-family variation was generally highly significant (p 〈 0.01) and nonsignificant, respectively. The variation observed among regenerants on the basis of hill plot testing was not duplicated in subsequent four-row plot experiments. On average, regenerant families yielded 28 and 5% less than the control in dryland and irrigated tests, respectively. Low yielding regenerants tended to produce fewer, lighter kernels per spike. Higher grain protein levels among regenerants were associated with low yields (r=0.85). This study demonstrated that putative somaclonal variation arising from tissue culture failed to produce genotypes agronomically superior to the parental cultivar, HY 320.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00039402
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  • 84
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    Heritable tissue culture induced variation in Zinnia marylandica (1992)
    Springer
    Euphytica 64 (1992), S. 81-89 
    Details
    ISSN: 1573-5060
    Keywords: interspecific hybrid ; somaclonal variation ; Zinnia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Adventitious shoots of Zinnia marylandica, an amphidiploid with limited genetic segregation, were regenerated from cotyledonary tissue on Murashige-Skoog (MS) media containing 0.2 or 22.2 μM thidiazuron (TDZ) and grown through flowering. Fisher's Test for Equal Variance indicated tissue culture induced plants had more variation than seed-derived control plants. Twelve of 149 (8%) plants derived from 0.2 μM TDZ and three of 23 (13%) plants from 22.2 μM TDZ had variant characters. Aberrant characteristics in self-pollinated variants included plant height, fertility, flower color and morphology, and were sexually transmitted, indicating genetic change had occurred. Aberrant characteristics not observed in regenerated plants arose in progeny.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023541
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  • 85
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    Survival and growth of pea protoplasts after transformation by electroporation (1992)
    Springer
    Plant cell, tissue and organ culture 30 (1992), S. 141-148 
    Details
    ISSN: 1573-5044
    Keywords: electroporation ; pea ; Pisum sativum L. ; protoplast ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protoplasts from two different pea cultivars, Belman and Filby, were stably transformed by direct gene transfer using electroporation. Transgenic calli could be obtained after selection, when hygromycin resistance was used as the selective trait introduced into the protoplasts, while no transformants were obtained when kanamycin resistance was used as selective marker in either of the two pea cultivars tested. The effect of the field strength on survival and division rates of the protoplasts was studied. Two different culture systems and osmotica were compared for induction of sustained divisions in and regeneration of transgenic callus from the protoplasts. The choice of the culture system had a considerable effect on the initial division frequency of the treated protoplasts, as well as on the later growth of the colonies. Transformation efficiency was monitored by histochemical GUS assay, and the transgenic nature of the calli selected for resistance against antibiotics was confirmed by DNA analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034308
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  • 86
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    Somaclonal variation in winter wheat: frequency, occurrence and inheritance (1992)
    Springer
    Euphytica 64 (1992), S. 1-10 
    Details
    ISSN: 1573-5060
    Keywords: tissue culture ; somaclonal variation ; plant breeding ; Triticum aestivum ; mutation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Plants were regenerated from immature embryo cultures of 35 winter wheat genotypes. A total of 7142 R2 spike lines from 1593 R1 plants were assessed in the field for somaclonal variants of morphological traits in 1985/86, 1986/87 and 1987/88. Selected variants were studied for their possible genetic basis. Populations of R1 plants were highly variable due mainly to the physiological disturbances resulting from the in vitro processes. Overall somaclonal variation frequencies were 14.2% on the R1 plant basis and 5.3% on the R2 spike basis. Spectra of the variants were similar in the different R2 populations with predominant variants being altered negatively in plant height, maturity, awnedness, and spike and plant types. Over 90% of the variants were observed in some spike progenies of individual regenerants, while the others appeared in all spike progenies of the regenerants and in progenies of different regenerants derived from the same explant embryos. Both uniform R2 variant families and spike lines were found in addition to the segregating variants, which constituted the majority. On average, in a variant family and line, 18 and 14% of their component lines and plants varied, respectively. Inheritability was demonstrated for the variations in both segregated and uniform variant families and spike lines. Of 134 variant selections tested, about 70% was classified inhernable. Both recessive and dominant gene mutations at one, two or three loci were evident in some of the variants as suggested by segregation data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023532
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  • 87
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    Evidence for sense RNA-mediated protection to PVYN in tobacco plants transformed with the viral coat protein cistron (1992)
    Springer
    Plant molecular biology 20 (1992), S. 631-639 
    Details
    ISSN: 1573-5028
    Keywords: coat protein ; potato virus Y ; tobacco ; transformation ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The coat protein (CP) cistron of the tobacco veinal necrosis strain of potato virus Y (PVYN), supplemented with translational start signals, was cloned into an Agrobacterium tumefaciens Ti transformation vector. Transformation of tobacco leaf discs resulted in 99 transgenic lines which were subsequently analysed for the presence and expression, at both the transcriptional and translational level, of the CP-gene. Although CP-specific RNA transcripts were produced in all plants no CP could be detected by several sensitive immunological techniques. Upon mechanical inoculation of progeny lines of selfpollinated original transformants (S1) with PVYN, protection levels of 20 and 95%, respectively, could be observed in two out of ten lines tested. This level of protection increased to 100% in the S2 progeny obtained from self-pollination of virus-protected S1 plants. Transformation of tobacco leaf discs with a PVYN CP construct from which the ATG start codon had been removed by site-directed mutagenesis resulted in 57 transgenic lines that all produced CP-specific transcripts. Mechanical inoculation with PVYN of S1 progeny plants of several of these lines resulted in resistance to a similar level and extent as in the S1 progeny of plants transformed with the intact CP cistron. The results obtained strongly suggest that the resistance observed in the transgenic plants is principally based on the presence of PVYN CP RNA sequences rather than on the accumulation of viral coat protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046448
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  • 88
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    Factors influencing Agrobacterium-mediated transient expression of gusA in rice (1992)
    Springer
    Plant molecular biology 20 (1992), S. 1037-1048 
    Details
    ISSN: 1573-5028
    Keywords: Agrobacterium ; rice ; transformation ; Ti plasmid ; GUS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transient expression of GUS in rice (Oryza sativa L.) mediated by Agrobacterium tumefaciens was characterized using binary vectors containing gusA genes that express minimal (pKIWI105 and pCNL1) or no (p35S-GUS-INT and pCNL56) GUS activity in bacteria. Four-day old seedlings obtained from seeds or immature embryos of rice were cut into shoot, root, and seed remnants and inoculated with various strains of A. tumefaciens. Transient GUS expression events were quantitated histochemically by determining the frequency of explants exhibiting blue spots indicative of GUS at four to six days after cocultivation with A. tumefaciens. A. tumefaciens strains that did not contain the gusA gene (At643) or a Ti-plasmid (At563 and At657) did not elicit any blue staining characteristic of GUS activity. Several parameters were important in obtaining efficient transient expression of GUS in rice mediated by A. tumefaciens. The growth regulator 2,4-D inhibited GUS expression if present during the seed germination period, but the presence of 6 mg/1 2,4-D during cocultivation of the explants with A. tumefaciens slightly enhanced GUS expression efficiency. All 21 rice cultivars tested expressed GUS after co-cultivation with A. tumefaciens. The GUS expression frequency was highest amongst the indica cultivars. The frequencies of GUS expression in japonica cultivars and in Oryza glaberrima cultivars (grown primarily in Africa) were generally one-half to one-third the level found for indica varieties. Leaf explants were more susceptible to A. tumefaciens-facilitated GUS expression than were roots or seed remnants. The vir genes of an agropine-type Ti-plasmid of A. tumefaciens were most effective in directing transient GUS expression in rice, whereas those of a nopaline-type and an octopine-type plasmid were less effective. We have also found that the frequency of transient expression of GUS was higher with pBIN19 as the precursor cloning vector than with pEND4K as the precursor cloning vector. Reasons for differences in effectiveness of these binary vectors are discussed. Using the conditions described here, A. tumefaciens-mediated frequencies of transient GUS expression in four-day old shoots of several rice cultivars were routinely in excess of 50%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028891
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  • 89
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    A free-radical hypothesis for the instability and evolution of genotype and phenotypein vitro (1992)
    Springer
    Cytotechnology 10 (1992), S. 93-124 
    Details
    ISSN: 1573-0778
    Keywords: hybridomas ; embryonic stem cells ; immortalization ; amine oxidase ; polyamines ; cell death ; crisis ; transformation ; aneuploidy ; senescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract It has been known for several decades that cultured murine cells undergo a defined series of changes, i.e., anin vitro evolution, which includes crisis, spontaneous transformation (‘immortalization’), aneuploidy, and spontaneous neoplastic transformation. These changes have been shown to be caused by thein vitro environment rather than an inherent instability of the murine phenotype or genotype. Serum amine oxidases were recently identified as a predominant cause of crisis. These enzymes generate hydrogen peroxide from polyamine substrates that enter the extracellular milieu. This finding implicates free-radical toxicity as the underlying cause ofin vitro evolution. We propose an oxyradical hypothesis to explain each of the stages ofin vitro evolution and discuss its significance for cytotechnology and long-term cultivation of mammalian cell types.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570888
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  • 90
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    Nonsymmetrical large deformation bending problem of circular thin plates (1992)
    Springer
    Applied mathematics and mechanics 13 (1992), S. 1149-1162 
    Details
    ISSN: 1573-2754
    Keywords: plate ; displacement ; nonlinear ; transformation ; perturbation method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract To begin with, in this paper, the displacement governing equations and the boundary conditions of nonsymmetrical large deflection problem of circular thin plates are derived. By using the transformation and the perturbation method, the nonlinear displacement equations are linearized, and the approximate boundary value problems are obtained. As an example, the nonlinear bending problem of circular thin plates subjected to comparatively complex loads is studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02456156
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  • 91
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    Transformations of thiocyanoalkyl phosphites and amidophosphites (1992)
    Springer
    Russian chemical bulletin 41 (1992), S. 2119-2120 
    Details
    ISSN: 1573-9171
    Keywords: transformation ; thiocyanoalkyl phosphites ; amidophosphites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The ratio of the alkoxy and dialkylamido groups in thiocyanoalkyl phosphites determines the structure of the transformation products of these compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00863384
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  • 92
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    Induction of stromal cell transformation in xenografts of human colonic carcinoma (1992)
    Springer
    Bulletin of experimental biology and medicine 113 (1992), S. 532-535 
    Details
    ISSN: 1573-8221
    Keywords: stromal cells ; transformation ; nude mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00840943
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  • 93
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    Efficient electropulse transformation of intact Candida maltosa cells by different homologous vector plusmids (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 8 (1992), S. 691-697 
    Details
    ISSN: 0749-503X
    Keywords: Candida maltosa ; electroporation ; transformation ; plasmid vectors ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Conditions for efficient and quick transformation by electroporation were developed in Candida maltosa. To investigate the efficiency of transformation with integrative as well as with autonomously replicating plasmids, a series of vectors was constructed for homologous transformation of the species. Transformants were obtained with different plasmids as covalently closed circular molecules and as linearized DNA. The influence of recipient strain and plasmid type as well as of cell number and parameters of the supplied electrical pulse on the transformation efficiency have been investigated. A maximum of 7000 transformants per 100ng of plasmid DNA was reached. The efficiency of transformation was compared with that of the LiCl method.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320080902
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  • 94
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    Molecular cloning and analysis of autonomous replicating sequence of Candida maltosa (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 8 (1992), S. 253-259 
    Details
    ISSN: 0749-503X
    Keywords: Candida maltosa ; automonous replicating sequence ; nucleotide sequence ; transformation ; RS15 protein ; intron ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A Candida maltosa chromosomal DNA fragment which confers high frequency transformation of C. maltosa and autonomous replication of recombinant plasmids was cloned and sequenced. Analysis of the nucleotide sequence of the cloned DNA revealed a sequence homologous for C. maltosa autonomously replicating sequence (ARS) elements. Vector pRJ1 for C. maltosa was constructed, which contained a 1.3 kb ARS sequence, pICEM-19H and the ADE1 gene of C. maltosa. Southern blot analysis suggested that the copy number of pRJ1 in C. maltosa was approximately 20 per genome. The sequence analysis also revealed an open reading frame, encoding a polypeptide with high homology (70%) to the RS15 protein of Brugia pagangi. This open reading frame has an intron with canonical sites for correct splicing in Saccharomyces cerevisiae.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320080403
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  • 95
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    Stable and unstable transformation by microinjection of macronucleoplasm in Paramecium (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 13 (1992), S. 118-125 
    Details
    ISSN: 0192-253X
    Keywords: Microinjection ; macronucleoplasm ; transformation ; Paramecium ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Transformation by microinjection of macronucleoplasm in Paramecium caudatum was investigated. Macronucleoplasm with three genetic markers (behavior, trichocyst, and mating type) was injected into the macronucleus. To facilitate microinjection, in most cases, paramecia were immobilized in a gelatin (7.5%) solution. The injected cells began to express a dominant gene (cnrA+ or cnrB+) of the donor 9-24 hr after injection. Expression did not require cell division suggesting injected macronucleoplasm was capable of expressing a phenotype. The amount of injected macronucleoplasm appears to correlate with the frequency of successful expression but not to correlate with the time required for expression. After a number of fissions, the injected cells produced clones which had cells expressing the phenotype of the donor. This suggests that injected macronucleoplasm was replicated and expressed in the recipient cell lines. The transformed clones were classified into two groups. In one group, transformation was stable. All cell lines derived from the injected cells expressed a phenotype similar to the heterozygote of donor and recipient cells. In the other group, transformation was unstable. During the first five to seven fissions after injection, at each division, cells produced one daughter cell which later reverted to the recipient phenotype. After this unstable period, cells no longer produced the recipient phenotype but produced the donor phenotype exclusively. Donor and recipient phenotypes were, thus, segregated in different cell lines. Observation of genetic markers and analysis by computer simulation shed light on the mode of transmission of injected macronucleoplasm. In stable transformation, injected macronucleoplasm appears to be distributed equally to daughter cells. In unstable transformation, injected macronucleoplasm is distributed only to one of the daughter cells at every division until about the fifth to seventh fission after injection and then begins to assort equally to daughter cells. The cell cycle stage at injection may influence the mode of transformation. Interspecific microinjection of macronucleoplasm from P. multimicronucleatum and P. tetraurelia to P. caudatum. resulted in the expression of foreign genes in P. caudatum. In one case, injection of macronucleoplasm of P. tetraurelia produced a stable transformant indicating replication of foreign macronucleoplasm in P. caudatum. This work reveals the mode of transformation by injected macronucleoplasm and shows the possibility of transformation among Paramecium species, which is significant in the study of the conservation of gene products and the mechanism of gene expression in different species. © 1992 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020130205
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  • 96
    Electronic Resource
    Electronic Resource
    Incorporation of the gene for a cell-cell channel protein into transformed cells leads to normalization of growth (1991)
    Springer
    The journal of membrane biology 124 (1991), S. 207-225 
    Details
    ISSN: 1432-1424
    Keywords: intercellular communication ; gap junction ; connexin ; growth control ; cDNA ; connexin43 ; cell-cell channel ; junctional communication ; transformation ; cancer etiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Incorporation of the gene for connexin 43, a cell-cell channel protein of gap junction, into the genome of communication-deficient transformed mouse 10T1/2 cells restored junctional communication and inhibited growth. Growth was slowed, saturation density reduced and focus formation suppressed, and these effects were contingent on overexpression of the exogenous gene and the consequent enhancement of communication. In coculture with normal cells the growth of the connexin overexpressors was completely arrested, as these cells established strong communication with the normal ones. Thus, in culture by themselves or in coculture, the connexin overexpressor cells grew like normal cells. These results demonstrate that the cell-cell channel is instrumental in growth control; they are the expected behavior if the channel transmits cytoplasmic growth-regulatory signals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01994355
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  • 97
    Electronic Resource
    Electronic Resource
    Agrobacterium rhizogenes-mediated transformation of Echinacea purpurea (1991)
    Springer
    Plant cell reports 10 (1991), S. 85-89 
    Details
    ISSN: 1432-203X
    Keywords: Agrobacterium rhizogenes ; alkamides ; Echinacea purpureal ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Echinacea purpurea seedlings were inoculated with several Agrobacterium rhizogenes strains in order to obtain hairy roots. Infection with A. rhizogenes strains LMG63 and LMG150 resulted in callus formation. Upon infection with strains ATCC 15834 and R1601 hairy roots were obtained. Opine detection confirmed transformation of E. purpurea. Comparative HPLC fingerprint analysis of the alkamides from natural plant source, control tissues, and transformed callus and roots indicated that transformed callus and hairy roots might be a promising source for continuous and standardized production of the dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamide and related amides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236463
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  • 98
    Electronic Resource
    Electronic Resource
    An evaluation of a somaclone ofDioscorea floribunda Mart & Gall (1991)
    Springer
    Cellular and molecular life sciences 47 (1991), S. 284-288 
    Details
    ISSN: 1420-9071
    Keywords: D. floribunda ; in vitro regeneration ; somaclonal variation ; diosgenin ; mixoploidy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 150 plants ofD. floribunda representing a single clone were regenerated from a stem tissue culture and regenerants were subjected to cytological, phenotypic and biochemical analysis from the pre-transfer stage to three vegetative growth cycles in the field. The plants could be subdivided into three cytological categories, namely, diploid, mosaic and tetraploid. Diploids, mosaics and the one tetraploid showed diversity amongst themselves with respect to internode length, content of chlorophyll and diosgenin. No marked difference in the length and nature of the leaf or in the type of stoma was recorded. Possible causes of the observed variation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01958162
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  • 99
    Electronic Resource
    Electronic Resource
    Production of islet cell antibodies from Epstein-Barr virus-transformed peripheral blood lymphocytes in Type 1 (insulin-dependent) diabetic patients (1991)
    Springer
    Diabetologia 34 (1991), S. 511-514 
    Details
    ISSN: 1432-0428
    Keywords: Islet cell antibodies ; Type 1 (insulin-dependent) diabetes ; Epstein-Barr virus ; peripheral blood lymphocytes ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Islet cell antibodies are usually detected in the sera of almost all Type 1 (insulin-dependent) diabetic patients within several months after onset of the disease. The antibodies then disappear quite early during the course of the disease. The present study was undertaken to detect islet cell antibody-producing clones in peripheral blood lymphocytes of Type 1 diabetic patients whose islet cell antibodies could not be detected in sera. Epstein-Barr virus-transformed lymphocytes were employed to enhance the production of antibodies and to detect the clones from peripheral blood lymphocytes. Peripheral blood lymphocytes were obtained from 40 islet cell antibody-negative Type 1 diabetic patients, 10 antibody-positive Type 1 diabetic patients, 30 Type 2 (non-insulin-dependent) diabetic patients and 40 normal control subjects. Epstein-Barr virus-transformed lymphocytes were cultured for 4 weeks and the culture supernatants were used for assay of islet cell antibodies. Islet cell antibody assays were performed by immunohistochemical methods using peroxidase-labelled protein A for IgG antibodies, peroxidase-labelled anti-human IgM antibodies for IgM antibodies and fresh frozen human pancreatic tissue. IgG-islet cell antibodies were detected in 26 islet cell antibody-negative patients (65%), eight antibody-positive patients (80%) and one Type 2 diabetic patient (3%) in the culture supernatants. Islet cell antibodies in the supernatants could not be detected in any of the control subjects. IgM-islet cell antibodies could not be detected in any of the patients or control subjects. These findings indicate that islet cell antibody-producing clones exist in peripheral blood lymphocytes from Type 1 diabetic patients whose islet cell antibodies cannot be detected in their sera and IgG-islet cell antibodies might be a specific characteristic of Type 1 diabetes. The detection of islet cell antibodies from Epstein-Barr virus-transformed lymphocytes may be useful in examining the role of autoimmune mechanisms in the development of disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403288
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  • 100
    Electronic Resource
    Electronic Resource
    The effects of acetosyringone and pH on Agrobacterium-mediated transformation vary according to plant species (1991)
    Springer
    Plant cell reports 9 (1991), S. 671-675 
    Details
    ISSN: 1432-203X
    Keywords: Agrobacterium tumefaciens ; Allium cepa ; Antirrhinum majus ; Brassica campestris ; Glycine max ; Nicotiana tabacum ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Expiants of five plant species (Allium cepa, Antirrhinum majus, Brassica campestris. Glycine max, and Nicotiana tabacum) were co-cultivated with three Agrobacterium tumefaciens strains under different conditions to assess the effects of acetosyringone and medium pH on strain virulence. Tumours were incited on all dicotyledonous species by strains N2/73 and A281. The presence of acetosyringone during co-cultivation generally enhanced the virulence of these strains, most markedly N2/73 on A. majus and G. max, and A281 on G. max. Strain Ach5 was virulent only on N. tabacum in the absence of acetosyringone, which, when present, extended the host range to include A. majus. There was evidence to suggest that acetosyringone may suppress virulence in some strain/plant species interactions. Virulence was affected in some cases by medium pH, but there was no general effect across plant species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235354
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