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  • 1990-1994  (17)
  • 1955-1959
  • 1990  (17)
  • somaclonal variation
  • transformation
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell reports 9 (1990), S. 26-29 
    ISSN: 1432-203X
    Schlagwort(e): Solanum melongena ; eggplant ; Agrobacterium tumefaciens ; kanamycin ; transformation ; shoot regeneration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Kanamycin resistant plants of Solarium melongena L. (eggplant) cv. Picentia were obtained following the cocultivation of leaf explants with Agrobacterium tumefaciens. A disarmed binary vector system containing the neomycin phosphotransferase (NPTII) gene as the selectable marker and chloramphenicol acetyltransferase (CAT) as a reporter gene was utilized. In vitro grown plants were used as sources of explants to produce transgenic plants on selective medium containing 100 mg/l kanamycin. The transformation and expression of the foreign genes was confirmed by DNA hybridizations, leaf disc assays, and by measuring NPTII and CAT enzyme activities. This technique is simple, rapid, efficient, and transgenic eggplants of this commercial cultivar have been transferred to soil where they have flowered and set seed.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1573-5028
    Schlagwort(e): direct gene transfer ; gene rearrangements ; Nicotiana tabacum ; particle gun ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Transgenic tobacco plants and progeny carrying coding sequences for neomycin phosphotransferase II (NPTII) and beta-glucuronidase (GUS) were recovered following microprojectile bombardment of tobacco leaves. Transgenic plants were regenerated from bombarded leaf pieces of tobacco cvs. ‘Xanthi’ and ‘Ky 17’ which were cultured in the presence of 100 or 200 μg/ml kanamycin for six to eight weeks. Among 160 putative transgenic plants from at least 16 independent transformation events 76% expressed NPTII, and 50% expressed GUS. Southern analysis of plants expressing either one or both of the enzymes indicated DNA in high molecular weight DNA in 8 of 9 independent transformants analyzed. Two independent transformants and their progeny were analyzed in detail. Analysis of progeny for quantitative enzyme levels of NPTII and GUS, and Southern analysis of parents and progeny clearly demonstrated that the genes were transmitted to progeny. One transformant demonstrated Mendelian ratios for seed germination on kanamycin-containing medium while the other transformant had non-Mendelian ratios. DNA analysis of progeny indicate complex integration of the plasmid DNA, and suggest that rearrangements of this DNA has occurred. These results are consistent with other methods of direct DNA uptake into cells, and verify that the microprojectile bombardment method is capable of DNA delivery into intact plant cells which can give rise to transgenic plants and progeny.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; conifers ; DNA hybridization ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The hypervirulent Agrobacterium tumefaciens strain A281 formed frequent tumors (31%) on Picea abies (Norway spruce), an economically important tree species in Swedish forests. Three-month-old seedlings were inoculated and tumors were established that grew hormone-independently in culture. Tumors contained agropine and mannopine/mannopinic acid as determined by acid pH paper electrophoresis. In addition, DNA hybridization studies showed that the DNA from these tumor lines contained sequences homologous to Ti plasmid T-DNA, whereas wild-type spruce seedling DNA did not. These results suggest that Agrobacterium vectors can be used for gene transfer into this important forest species.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1573-5028
    Schlagwort(e): cytokinin ; tumor formation ; isopentenyltransferase gene ; Nicotiana ; genetic tumors ; polymerase chain reaction (PCR) ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The shooty morphology of a nontumorous amphidiploid mutant of Nicotiana glauca Grah. x N. langsdorffii Weinm. was restored by cytokinins, whether exogenously applied or endogenously produced by transformation of the mutant with a transfer DNA (T-DNA) cytokinin-biosynthesis gene (isopentenyltransferase; ipt). Auxins alone did not confer this effect. Similar transformation was not achieved for the parental species. In the case of transformation with the ipt gene, selection of the transformed tissues was based on its hormone-independent growth in the presence of the antibiotic kanamycin. Transformed tissues exhibited a shooty morphology, indistinguishable from that of wildtype genetic tumors N. glauca x N. langsdorffii. This altered phenotype was caused by the presence and constitutive expression of the ipt gene. The insertion and expression of this gene in transformed tissues was confirmed by using the polymerase chain reaction (PCR) technique as well as conventional molecular hybridization analysis. Expression of the ipt gene led to an elevated level of cytokinin in the transformed mutant tissues. This evidence supports the notion that genetic tumors are caused, at least in part, by elevated levels of cytokinin in interspecific hybrids.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 14 (1990), S. 785-792 
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium rhizogenes ; Agrobacterium tumefaciens ; root induction ; tzs ; Linum usitatissimum L. ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Root induction on flax (Linum usitatissimum L.) cotyledon explants by Agrobacterium rhizogenes strain 1855 is markedly increased by co-inoculation with disarmed A. tumefaciens strain LBA 4404 containing a plasmid carrying the tzs gene of pTiC58. Most of the roots (estimated to be more than 90%) were transformed. This effect is most likely due to the secretion of trans-zeatin by A. tumefaciens stimulating the division of plant cells making them more receptive to transformation by A. rhizogenes, although other explanations are possible. This observation supports the idea that the tzs gene, although not essential for transformation, may promote transformation. An obvious application for genetic engineering experiments involving transformation by A. rhizogenes, is to include a vir-induced tzs gene in the transformation system to help maximize transformation efficiency.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1573-5028
    Schlagwort(e): antisense ; gene expression ; plants ; regulation ; RNA ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have shown leaf-specific inhibition GUS gene expression in transgenic Nicotiana plants using an antisense RNA with a 41-base homology spanning the translation start codon of the gene. GUS was expressed from the nominally constitutive 35S promoter and the antisense RNA was expressed from the light-regulated ca/b promoter of Arabidopsis thaliana. A range of GUS inhibition from 0 to 100% was obtained by screening a small population of transgenic plants and the specific levels of inhibition observed were stably inherited in two generations. An antiGUS ‘gene’ dosage effect was observed in plants which were homozygous for antiGUS. RNA detection results suggest that duplex formation with the 41 base pair antiGUS RNA destabilized the GUS mRNA and that an excess of antisense. RNA was not required. Our results demonstrate the potential of antisense RNA as a strategy for obtaining plant mutants, especially ‘down mutations’ in essential genes where only a short 5′ sequence of the mRNA is required. They also suggest that the ‘position effect’ on gene expression could be used in conjunction with an antisense RNA strategy to provide a versatile approach for crop improvement.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 14 (1990), S. 815-824 
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium tumefaciens ; hypocotyls ; Nicotiana alata ; regeneration ; self-incompatibility ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A transformation and regeneration system has been developed for Nicotiana alata, a plant which is being intensively studied as a model of gametophytic self-incompatibility. Plantlets can be regenerated efficiently from seedling hypocotyls. Kanamycin-resistant, transformed plants have been obtained by cocultivation of regenerating hypocotyls with Agrobacterium tumefaciens strain LBA4404 containing a binary vector. The transformation frequency was low with 〈1% of tissue explants regenerating transformed plants. The transformed plants contained from one to three copies of the introduced DNA. In most cases, the kanamycin resistance phenotype was transmitted to the offspring as a normal Mendelian factor. In one unusual case, none of the offspring inherited the kanamycin resistance of the transformed maternal parent. This plant may have been chimeric or the kanamycin resistance gene may have been inactivated.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Cancer and metastasis reviews 9 (1990), S. 93-98 
    ISSN: 1573-7233
    Schlagwort(e): transformation ; progression ; autotrophs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In 1984, Philippe Shubik wrote in an editorial in the Journal of the National Cancer Institute [1] that: ‘In terms of general biology, the multicellular organisms have evolved a complex series of defensive responses to extracellular injury involving various inflammatory reactions and their systemic concomitants. Needless to say, these reactions are by no means always successful from the standpoint of the host and indeed may well be the immediate cause of the obvious ill effects noted. The unicellular organisms, in contrast, react to injury by dividing and moving. In the search for the features that may link chemical, physical, and viral carcinogens apart from their ability to induce neoplasia, only one characteristic in common is obvious, namely, their ability to produce intracellular change or injury while leaving the cell viable. Perhaps the initial and fundamental characteristic of neoplasia is a reversion of the cell to unicellular behavior. Division and invasiveness are the characteristics of the neoplastic cell, and increased motility certainly seems to be the most likely mechanism for invasion’. Dr. Shubik presented these views as a basis for ‘further discussion’ regarding the nature of the neoplastic response. We hope that this presentation will augment Shubik's plea by reviewing his idea in the context of our current knowledge of tumor development. In addition, we will attempt to integrate the concept of the unicellular behavior of tumor cells with Foulds' [2] and subsequently Nowell's [3] insightful hypothesis concerning tumor progression.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Plant foods for human nutrition 40 (1990), S. 283-288 
    ISSN: 1573-9104
    Schlagwort(e): heat ; transformation ; fatty acids ; leaf proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Freeze-dried leaf protein concentrate (LPC) contained 18% lipids in which linolenic acid (61.5%) was the major component. Linolenic acid in LPC was almost stable when stored at ambient temperature (30 to 35°C) and exposed to air for 24 weeks. Heating of LPC (50 to 200°C) in presence of moisture (6 to 12%) progressively increased the rate of destruction of linolenic acid. Below 100°C the presence of lipids did not affect the protein quality but at higher temperatures due to the lipid oxidation protein quality as estimated by dye-binding capacity was considerably affected.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 51 (1990), S. 249-256 
    ISSN: 1573-5060
    Schlagwort(e): Festuca arundinacea ; tall fescue ; chromosome pairing ; electrophoresis ; isoenzyme ; meiotic analyses ; somaclonal variation ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary This study was conducted using the isozymes ACP-1, ADH-1, GOT-2, GOT-3, MDH, 6-PGD-1 and PGI-2 to: a) compare isozyme banding patterns of tall fescue somaclones with parents and b) correlate tissue culture-induced chromosome abnormalities with variant banding patterns. The 174 somaclones were grouped into seven categories based on their meiotic analyses and time of regeneration from culture. Differences in isozyme frequency between categories compared by chi-square tests were greatest for MDH, 6-PGD-1 and PGI-2, and least for ACP-1. The most significant differences in frequency were found between somaclones and parents. In comparisons of somaclone categories, the most different isozyme distributions were between the early vs. late regenerated somaclones. No significant differences in isozyme frequencies were found between all 42-chromosome somaclones vs. aneuploid somaclones and the three somaclone groups (42-normal, 42-abnormal, aneuploid) compared to each other. This study suggests that culture-induced isozyme variation alters the distribution of the isozyme phenotypes, but is not directly correlated with chromosome abnormalities.
    Materialart: Digitale Medien
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 46 (1990), S. 35-41 
    ISSN: 1573-5060
    Schlagwort(e): forage legumes ; Lotus corniculatus ; birdsfoot trefoil ; somaclonal variation ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Seventy-two plants regenerated from leaf-derived calli of a single plant of Lotus corniculatus have been evaluated for several morphological and agronomical traits. The analysis of selfed and polycross progenies of the regenerants indicates that the variation among regenerants was, at least in part, of genetic origin. Most of the mutations induced by tissue culture were recessive and were detected only after sexual propagation. Although in vitro culture had a depressive effect for most of the traits, the selfed progenies of 2 regenerants displayed higher values for leaflet width and seed yield than the selfed progeny of the initial plant. However the somaclonal variation did not increase the variation for any trait with respect to the variation of the donor cultivar of the initial plant.
    Materialart: Digitale Medien
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  • 12
    ISSN: 1573-5060
    Schlagwort(e): Brassica juncea ; Indian mustard ; in vitro selection ; salt-tolerance ; somaclonal variation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary In vitro selection of salt tolerant plants of Brassica juncea L. (Indian mustard) cv. Prakash has been accomplished by screening highly morphogenic cotyledon explant cultures on high NaCl media. Out of a total of 2,620 cotyledons cultured on high salt medium, 3 survived, showed sustained growth and regenerated shoots. They were multiplied by axillary bud culture on NaCl free medium. The salt-selected shoots retained salt tolerance following 3 month of growth and multiplication on control medium. While two of these somaclones flowered and set seeds, third one grew slowly, had abnormal leaf morphology and was sterile. The seed of the two fertile plants were sown in the field to raise R1 segregating generation. Data were recorded for field, other agronomic components and oil content. The somaclonal lines, both selected salt-tolerant and non-selected, showed tremendous amount of variation for all the characters studied. One of the two tolerant somaclones invariably showed reduced height, longer reproductive phase and higher 1000 seed weight. Based on the agronomic performance of R1 plants of these somaclones, some plants were selected and their progeny were evaluated for agronomic performance under standard field conditions and salt-tolerance in the greenhouse using sand pot culture method. Most of the lines bred true for their specific characteristics. In the greenhouse, selected salt-tolerant somaclones (SR-2 and SR-3) performed better for plant growth, yield and other agronomic traits at higher salt treatments, indicating thereby that salt-tolerance trait selected in vitro was expressed in the whole plants and is genetically stable and transmitted onto the progeny. The two tolerant lines, however, differed in their salt-tolerance during vegetative and reproductive phases as indicated by their salt-tolerance and stress susceptibility indices. The mechanism of salt-tolerance is not clear and needs to be further investigated.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 23 (1990), S. 39-44 
    ISSN: 1573-5044
    Schlagwort(e): albino ; aspen ; chimera ; callus culture ; somaclonal variation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Pigment as well as isozyme variations were observed among aspen (Populus tremuloides Michx.) plants regenerated from callus cultures. Out of more than 600 plantlets, two chimeric plants (one with green base and two albino shoots and the other with an albino shoot) were produced. Callus derived from albino shoots produced albino as well as chimeric plants when transferred to shoot inducing medium. Isozyme patterns of 119 plants were examined by starch gel electrophoresis. Thirty plants showed variation in shikimic dehydrogenase isozyme and 41 in isocitric dehydrogenase. Variation was also observed in malate dehydrogenase and phosphoglucose isomerase. No variation was seen in 6-phosphogluconate dehydrogenase. Pigment variation was not associated with any isozyme changes.
    Materialart: Digitale Medien
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  • 14
    ISSN: 1572-994X
    Schlagwort(e): HPV 16 ; transformation ; NIH 3T3 cells ; polycistronic mRNA ; cDNA cloning ; sequencing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We have cloned cDNA of the major 1.8 kb mRNA from HPV 16-transformed NIH 3T3 cells (PM3T3). The entire nucleotide sequences of this cDNA were determined and compared with prototype HPV 16 genomic DNA sequences. The 5′-end of the cDNA was flanked by approximately 300 bp of cellular sequences, and the 3′-end of the cDNA sequences contained poly A residues following at nt 4230. HPV 16 sequences began at nt 124, downstream of a major viral p97 promoter, within the E6 open reading frame (ORF). The first splice donor site was at nt 226 and the splice acceptor site was at nt 409, suggesting that the E6 gene is inert. Second splice donor and acceptor sites were located at nt 880 and at nt 3357, respectively. This mRNA was thus shown to consist of three exons, resulting in polycistronic mRNA containing three potentially functional virus early genes-E7, E1^E4, and E5-actively transcribed in the transformant.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 22 (1990), S. 135-145 
    ISSN: 1573-5044
    Schlagwort(e): co-transformation ; liposomes ; tobacco ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A system for the transformation of tobacco mesophyll protoplasts using pH-sensitive liposomes was developed. Plasmid DNA (plGVneo23) encoding the NPT-II gene for kanamycin resistance was entrapped in pH-sensitive liposomes composed of dioleolphosphatidylethanolamine, cholesterol and oleic acid. These liposomes release their contents at low pH and are capable of delivering their contents into the cytoplasm of protoplasts. Kanamycin-resistant colonies were reproducibly recovered from transformed protoplasts at an average frequency of 1.62×10-4 at pH 7.5. Plants regenerated from transformed cell lines were normal in appearance and were fertile. NPT-II activity was detected in leaf extracts of transformed, kanamycin-resistant plants and the presence of NPT-II DNA in the tobacco genome was shown by Southern blots. Analysis of self-pollinations and reciprocal crosses to non-transformed plants indicated that kanamycin resistance segregated as a dominant nuclear marker. Co-transformation of protoplasts with liposomes containing two selectable markers indicated that co-transformation occurred with a frequency of approximately 23%.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Cell biology and toxicology 6 (1990), S. 353-363 
    ISSN: 1573-6822
    Schlagwort(e): Transforming growth factor β1 ; cell cycle ; liver ; epithelial cell line ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: The effects of TGFβ1 on cell cycle events in a rat liver derived epithelial cell line (BL9) and in two in vitro transformants of this line were studied by flow cytometry. Using either ethidium bromide staining or the incorporation of bromodeoxyuridine to evaluate DNA synthesis it was shown that TGFβ1 prevented the entry of G0/G1 phase BL9 cells into S phase. TGFβ1 did not exert its inhibitory effect(s) on DNA synthesis by the modulation of early events in the cell cycle. The tumorigenic transformed BL9 cell lines gave contrasting responses to the effects of TGFβ1. DNA synthesis in a BL9 cell line derived by transfection with an active N-ras oncogene was unaffected by TFGβ1 and thus appeared refractory to its growth controlling effects. On the other hand cells from a BL9 cell line derived by in vitro transformation with activated aflatoxin B1 retained their sensitivity to the effects of TGFβ1. Thus the loss of the inhibitory effect of TGFβ1 on DNA synthesis is not obligatory for the malignant transformation of rat liver epithelial cells.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 11 (1990), S. 391-395 
    ISSN: 0192-253X
    Schlagwort(e): Lipofectin ; slime mould ; transformation ; Life and Medical Sciences ; Genetics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: We have studied the transient expression, in Dictyostelium cells growing on a bacterial food source, of a construct containing the coding region of the firefly luciferase gene inserted downstream of a Dictyosteliumactin promoter. The fusion gene is not detectably expressed when DNA is introduced by calcium phosphate precipitation or by electroporation, but it is expressed when introduced using cationic liposomes (lipofectin). Using this latter procedure, we are able to transform cells with a G418 resistance vector and select stable, drug-resistant transformants at a relatively low, but workable, efficiency. This technique will allow molecular genetics to be applied to the many important nonaxenic Dictyostelium strains.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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