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  • 1990-1994  (56)
  • 1955-1959  (9)
  • 1920-1924
  • 1850-1859
  • genetic engineering
  • somaclonal variation
  • 1
    ISSN: 1573-5028
    Keywords: anti-bacterial protein ; genetic engineering ; precursor processing ; synthetic gene ; thionin ; transgenic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hordothionins (HTHs) are small anti-bacterial proteins present in barley endosperm which are processed from larger precursor proteins, consisting of an amino-terminal signal peptide (SP), the mature highly basic HTH and a carboxy-terminal acidic peptide (AP). Different HTH precursor proteins were expressed in tobacco to study the effects of the pre-sequences (SP) and pro-sequences (AP) on expression, processing, sorting and biological activity and hence the feasibility of engineering bacterial disease resistance into crops which lack these proteins. Maximum HTH expression levels of approximately 0.7% (11 μmol/kg) of total soluble protein in young tobacco leaves were obtained using a semi-synthetic gene construct encoding a complete chimaeric HTH precursor protein. Tenfold lower HTH expression levels (maximum 1.3 μmol/kg) were obtained using synthetic gene constructs without the AP-coding sequence and no expression was found in plants containing synthetic HTH gene constructs without SP-and AP-coding sequences. In both cases where expression was found, the precursors were apparently correctly processed, although the HTH produced in plants containing a construct without AP sequence appeared to be slightly modified. No effect on plant phenotype was observed. Localization studies indicated that the HTH was in identical fractions of plants expressing the two different precursors, albeit at a different ratio, and was not secreted into the intercellular spaces of leaves or culture medium by protoplasts. Our results indicated that the AP is not involved in sorting and suggested that it might facilitate transport through membranes. The in vitro toxicity of HTH isolated from transgenic tobacco plants expressing the two different precursor proteins for the bacterial plant pathogen Clavibacter michiganensis subsp. michiganensis appeared similar to that of the HTH purified from barley endosperm.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5028
    Keywords: Antibody ; coordinated expression ; genetic engineering ; protein assembly ; root ; secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To explore the feasibility of employing antibodies to obtain disease resistance against plant root pathogens, we have studied the expression of genes encoding antibodies in roots of transgenic plants. A model monoclonal antibody was used that binds to a fungal cutinase. Heavy and light chain cDNAs were amplified by PCR, fused to a signal sequence for secretion and cloned behind CaMV 35S and TR2′ promoters in a single T-DNA. The chimeric genes were cloned both in tandem and in a divergent orientation. The roots of tobacco plants transformed with these constructs produced antibodies that were able to bind antigen in an ELISA. Immunoblotting showed assembly to a full-size antibody. In addition, a F(ab′)2-like fragment was observed, which is probably formed by proteolytic processing. Both antibody species were properly targeted to the apoplast, but the full-size antibody was partially retained by the wall of suspension cells. The construct with divergent promoters showed a better performance than the construct with promoters in tandem. It directed the accumulation of functional antibodies to a maximum of 1.1% of total soluble protein, with half of the plants having levels higher than 0.35%. The high efficiency of this construct probably results from coordinated and balanced expression of light and heavy chain genes, as evidenced by RNA blot hybridization.
    Type of Medium: Electronic Resource
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  • 3
    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
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  • 4
    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
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  • 5
    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
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 77 (1994), S. 277-282 
    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
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 80 (1994), S. 111-118 
    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
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Biodiversity and conservation 3 (1994), S. 176-183 
    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
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    World journal of microbiology and biotechnology 10 (1994), S. 139-144 
    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
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    World journal of microbiology and biotechnology 10 (1994), S. 243-248 
    ISSN: 1573-0972
    Keywords: Biotechnology ; development ; genetic engineering ; sub-Saharan Africa ; sustainable
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Whether development is defined by the long-standing economic parameter of per capita gross national product (GNP) or by the newly introduced Human Development Index (HDI), which is not based exclusively on per capita GNP, the countries of sub-Saharan Africa rank at or near the bottom of the developing world. Agriculture and agro-based processing are the mainstays of the economies of the majority of these countries. Because of this, and also because many of the diseases endemic in these countries are communicable, the application of modern biotechnology (including genetic engineering, tissue culture and monoclonal antibody technology) and related biotechnologies could play an important part in creating sustainable development in the region. There is, therefore, an urgent need to train more of the region's indigenous citizens, and to equip more laboratories, in modern biotechnology. It is suggested that, in order to accelerate the harnessing of the fruits of biotechnology, more countries in the region should affiliate with the International Centre for Genetic Engineering and Biotechnology (ICGEB). It is further suggested that a regional equivalent of the ICGEB be built and the services of non-governmental biotechnology organizations used.
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 147-153 
    ISSN: 0006-3592
    Keywords: aqueous two-phase systems ; β-galactosidase ; T4 lysozyme ; partitioning ; charge modifications ; genetic engineering ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We have examined the effect of genetically engineered charge modifications on the partitioning behavior of proteins in dextran/polyethylene glycol two-phase systems containing potassium phosphate. By genetically altering a protein's charge, the role of charge on partitioning can be assessed directly without the need to modify the phase system. The charge modifications used are of two types: Charged tails of polyaspartic acid fused to β-galactosidase and charge-change point mutations of T4 lysozyme which replace positive lysine residues with negative glutamic acids. The partition coefficient Kp for these proteins was related to measured interfacial potential differences Δφ using the simple thermodynamic model, In Kp = In Ko + (F/RT)Zp δφ. The protein net charge Zp was determined using the Henderson-Hasselbalch relationship with modifications based on experimentally determined titration and isoelectric point data. It was found that when the electropartitioning term Zp δφ was varied by changing the pH, the partitioning of T4 lysozyme was quantitatively described by the thermodynamic model. The β-galactosidase fusions displayed qualitative agreement, and although less than predicted, the partitioning increased more than two orders of magnitude for the pH range examined. Changes in the partitioning of lysozyme due to the various mutations agreed qualitatively with the thermodynamic model, but with a smaller than expected dependence on the estimated charge differences. The β-galactosidase fusions, on the other hand, did not display a consistent charge based trend, which is likely due either to the enzyme's large size and complexity or to nonelectrostatic contributions from the tails. The lack of quantitative fit with the model described above suggests that the assumptions made in developing this model are oversimplified. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 56 (1994), S. 168-170 
    ISSN: 0730-2312
    Keywords: abzyme ; bacteriostatic agent ; bioactive material ; biomimetic structure ; biosensor ; blood coagulation ; ceramic ; coating ; combinatorial synthesis ; drug delivery ; encapsulation ; enzyme ; extracorporeal device ; genetic engineering ; implant ; in vitro enolution ; LB film ; liqid ; liposome ; molecular imprinting ; molecular machine ; nanostructure ; orthopedics ; porey ; engineering ; sensor ; silk ; S-layer ; surface ; smart material ; synthetic chemistry ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Materials that mimic or extend the properties of natural molecules are being developed for medical appoications. Recent breakthroughs in genetic engineering, polymer synthesis, molecular self-assmbly and related areas are greatly expanding the variety of structures available for use in physiological settings.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 61 (1994), S. 273-281 
    ISSN: 0268-2575
    Keywords: fed-batch culture ; pH-stat ; recombinant Escherichia coli ; genetic engineering ; fuzzy control ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the cultivation of genetically engineered Escherichia coli it is very important to control the substrate concentration at an appropriate level in order to avoid the accumulation of acetate, thereby elevating the expression level of plasmid-encoded protein. In this paper, a pH-stat mode of fuzzy control was considered for the overexpression of β-galactosidase in the fed-batch cultivation of recombinant E. coli. In the simple pH-stat fuzzy control, the response of pH change in the culture broth to the feeding rate of glucose was used to estimate the glucose consumption rate. In the modified pH-stat fuzzy control, the glucose consumption rate was accurately estimated by using pH change and the change in the carbon dioxide content of the exhaust gas. With this control strategy, the cell density could be increased to 72 g DCW dm-3, which was twofold higher than that attained in the cultivation with the simple pH-stat fuzzy control. The bulk β-galactosidase concentration was increased to 4150 U cm-3, which was threefold higher than when the simple pH-stat control was used.
    Additional Material: 6 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 49 (1993), S. 225-234 
    ISSN: 1420-9071
    Keywords: Ecological theory ; environmental safety ; exotic species ; genetic engineering ; introduced species ; recombinant DNA ; risk analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The exotic or non-indigenous species model for deliberately introduced genetically engineered organisms (GEOs) has often been misunderstood or misrepresented. Yet proper comparisons of ecologically competent GEOs to the patterns of adaptation of introduced species have been highly useful among scientists in attempting to determine how to apply biological theory to specific GEO risk issues, and in attempting to define the probabilities and scale of ecological risks with GEOs. In truth, the model predicts that most projects may be environmentallysafe, but a significant minority may be very risky. The model includes a history of institutional follies that also should remind workers of the danger of oversimplifying biological issues, and warn against repeating the sorts of professional misjudgments that have too often been made in introducing organisms to new settings. We once expected that the non-indigenous species model would be refined by more analysis of species eruptions, ecological genetics, and the biology of select GEOs themselves, as outlined. But there has been political resistance to the effective regulation of GEOs, and a bureaucratic tendency to focus research agendas on narrow data collection. Thus there has been too little promotion by responsible agencies of studies to provide the broad conceptual base for truly science-based regulation. In its presently unrefined state, the non-indigenous species comparison would overestimate the risks of GEOs if it were (mis) applied to genetically disrupted, ecologically crippled GEOs, but in some cases of wild-type organisms with novel engineered traits, it could greatly underestimate the risks. Further analysis is urgently needed.
    Type of Medium: Electronic Resource
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  • 15
    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
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    European journal of plant pathology 99 (1993), S. 259-268 
    ISSN: 1573-8469
    Keywords: antibacterial ; antimicrobial ; genetic engineering ; thionin ; toxicity assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Purothionins (PTHs) and hordothionins (HTHs) were purified by cation-exchange chromatography from petroleum-ether extracts of wheat and barley flour respectively. The HTHs could be separated into two fractions, HTH-1 and HTH-2. Radial diffusion assays and micro-plate broth dilution assays with a number of plant pathogenic bacteria showed that these proteins were toxic forClavibacter michiganensis subsp.michiganensis, the causal agent of bacterial canker on tomato,C. m. subsp.sepedonicus, the causal agent of ring rot on potato, andXanthomonas campestris pv.vesicatoria, the causal agent of a spot disease on tomato and pepper. Only minor differences in toxicity between PTHs and HTHs, and between HTH-1 and HTH-2, were detected. Minor differences in toxicity of these thionins were also detected for different strains of these bacteria. The use of these plant proteins for engineering bacterial disease resistance into solanaceous crops will be discussed.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 67 (1993), S. 71-78 
    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.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 74 (1993), S. 165-185 
    ISSN: 1573-5060
    Keywords: transgenic legumes ; genetic engineering ; particle bombardment ; Agrobacterium ; direct DNA transfer ; crop legumes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The absence of variety-independent gene transfer methods for major agronomic species has, until now, limited the usefulness of recombinant DNA techniques to crop improvement programs. Until recently, only Solanaceous crops could be used to study fundamental and applied problems in plant sciences. During the past five years rapid advances in cell biology, in combination with the development of novel gene transfer methodology allowed utilization of the tools of plant molecular biology in conventional breeding programs. Cereal and leguminous species were considered to be recalcitrant to genetic manipulation. As a result of the development of direct DNA transfer methodology into organized tissue, we are now in a position to introduce any foreign gene into almost all of the major cereals and legumes. This can be achieved efficiently, often in a variety-independent fashion. The object of this review is to provide a comprehensive account of the state of the art in gene transfer for the cultivated leguminous crops. Important oilseed and feed species primarily in industrialized countries, as well as minor but equally important species for sustaining growth populations in developing countries will be examined. Advantages of the various gene transfer methods that were shown to be useful for specific crops, as well as limitations and problems associated with each crop and gene transfer method will be discussed. Data from field trials of transgenic legumes, where available, will be presented.
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  • 19
    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.
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  • 20
    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.
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  • 21
    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.
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  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 35 (1993), S. 99-106 
    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.
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  • 23
    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.
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  • 24
    ISSN: 1573-5028
    Keywords: genetic engineering ; phage P1 ; recombinase ; luciferase ; selectable markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Cre-lox site-specific recombination system of bacteriophage P1 was used to excise a firefly luciferase (luc) gene which had previously been incorporated into the tobacco genome. The excision event was due to site-specific DNA recombination between two lox sequences flanking the luc gene and was catalyzed by the Cre recombinase introduced by cross-fertilization. Recombination resulted in the fusion of a promoter with a distally located hygromycin phosphotransferase (hpt) coding sequence and the excision event was monitored as a phenotypic change from expression of luc to expression of hpt. The efficiency of recombination was estimated from the exchange of gene activity and confirmed by molecular analysis. The relevance to potential applications of site-specific deletion-fusion events for chromosome engineering are discussed.
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  • 25
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    European journal of plant pathology 98 (1992), S. 1-12 
    ISSN: 1573-8469
    Keywords: genetic engineering ; resistance genes ; transgenic virus resistance ; viral genes ; virus interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Knowledge of the nucleotide sequences in the genomic nucleic acid of several potato viruses has enabled the open reading frames to be identified. These open reading frames are expressed by a variety of strategies, to produce proteins with functions in virus nucleic acid replication, virus particle production, cell-to-cell transport of virus and virus transmission by vectors. The activity of such proteins depends on their interactions with other viral or non-viral materials. Several other biological properties of plant viruses can also be related to individual viral gene products. For example, in plants co-infected with a specific pair of unrelated viruses, one virus can benefit from an ability to use the gene product of the second virus in replication, cell-to-cell transport or transmission by vectors. Similarly, different host resistance genes are targeted against viral replicase, movement protein or coat protein. Thus it is becoming possible to relate gene-for-gene (or more accurately, viral gene domain-host gene) interactions to events at the molecular level. Genetically engineered resistance to plant viruses likewise can be targeted against individual viral genes, and probably also against viral regulatory sequences. Such transgenic resistance seems likely to be as durable as conventional host resistance but durability should be improved by producing plants with combinations of resistances of different kinds, either conventional or genetically engineered, or both.
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  • 26
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    Euphytica 64 (1992), S. 81-89 
    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.
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  • 27
    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.
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  • 28
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    Euphytica 60 (1992), S. 221-228 
    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.
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  • 29
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    Plant cell, tissue and organ culture 28 (1992), S. 207-213 
    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.
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  • 30
    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.
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  • 31
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    Plant cell, tissue and organ culture 29 (1992), S. 37-42 
    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.
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  • 32
    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.
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  • 33
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    European journal of plant pathology 98 (1992), S. 29-36 
    ISSN: 1573-8469
    Keywords: genetic engineering ; resistance genes ; transgenic virus resistance ; viral genes ; PVX ; PVY ; PLRV
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To engineer resistance against potato virus X (PVX), the viral coat protein (CP) gene has been introduced into two potato cultivars. Stable expression of the gene in transgenic clones throughout the growing season has been obtained and resulted in considerably increased virus resistance. With varying frequencies depending on the original cultivar used, true-to-type PVX resistant transgenic clones have been obtained. Since deviant light sprout characteristics were invariably associated with aberrations in plant phenotype, they can be used in procedures to early screen for deviations. Furthermore, it has been possible to unequivocally discriminate between the original untransformed and independent transgenic cultivars. Although no relation has been found between the presence, if any, of the CP of potato virus Y (PVY) or potato leafroll virus (PLRV) in CP gene transgenic potato, appreciable levels of resistance to these viruses has been obtained. This suggests that the mechanism by which a viral CP gene in the potato genome evokes resistance, differs amongst various viruses.
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  • 34
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    Cellular and molecular life sciences 47 (1991), S. 284-288 
    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.
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  • 35
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    Journal of agricultural and environmental ethics 4 (1991), S. 101-107 
    ISSN: 1573-322X
    Keywords: agricultural bioethics ; bovine somatotropin ; ownership of germ plasm ; genetic engineering ; animal rights ; intellectual property rights
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
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  • 36
    ISSN: 1573-5028
    Keywords: storage protein ; genetic engineering ; transgenic plants ; zeins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chimeric genes composed of the β-phaseolin promoter, an α-zein coding sequence and its modified versions containing lysine codons, and a β-zein polyadenylation signal were inserted into the genome of tobacco by Agrobacterium-mediated transformation. α-Zein mRNA levels in the transgenic tobacco seeds 20 days after self-pollination varied between 1.0% and 2.5% of the total mRNA population. At 25 days after pollination the 19 kDa α-zein was immunologically detected with a polyclonal antiserum in protein extracts from the seeds of transgenic plants. The transgenic plant with the highest level of zein gene expression had an α-zein content that was approximately 0.003% of the total seed protein. The amount of α-zein in other transgenic plants varied between 1 × 10−4% and 1 × 10−5% of the total seed protein. The differences in the amounts of mRNA and protein did not correlate with the lysine substitutions introduced into the α-zein protein. Polysomes translating α-zein mRNA isolated from tobacco seeds contained fewer ribosomes than those from maize endosperm, but this did not appear to be the cause of the inefficient protein synthesis. In vivo labelling and immunoprecipitation indicated that newly synthesized α-zein was degraded in tobacco seeds with a half-life of less than 1 hour.
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  • 37
    ISSN: 1573-0778
    Keywords: genetic engineering ; Namalwa cells ; perfusion culture ; scaling-up ; serum-free medium ; stable production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract We investigated the basic technology of cell culture conditions for production of useful substances such as cytokines, and related proteins produced by Namalwa cells. Namalwa cells (Klein, 1972), human B lymphoblastoid cells, were used for large scale production of alpha-interferon (Klein, 1979). Namalwa KJM-1, a subline of Namalwa cells, adapted to serum- and albumin-free medium, can grow at a high density above 1 × 107 cells/ml in suspension mode by the use of a perfusion culture system, Biofermenter™, containing a cone-type cell-sedimentation column as cell separator (Sato, 1983). Several kinds of cytokine cDNA can be introduced and expressed in Namalwa KJM-1 cells (Miyaji, 1990a,b,c). Some of these were produced in large quantities by use of a gene amplification method with dhfr (Miyaji, 1990c), even though the Namalwa KJM-1 cells contained endogenous dhfr genes. For stable production of the target protein, Namalwa KJM-1 cells are very useful host cells, because they have no effective endogenous protease activity in the conditioned medium. Using Biofermenter with micro-silicone fibers and a dialysis system, the specific productivity of the target proteins was not depressed at a high cell density.
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  • 38
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    Sociological forum 6 (1991), S. 551-565 
    ISSN: 1573-7861
    Keywords: agriculture ; capitalism ; development ; world economy ; Third World ; genetic engineering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Sociology
    Notes: Abstract Frederick Buttel was one of the pioneers in studying the social impacts of biotechnology, claiming originally that it will involve profound changes in social structure. Recently Buttel turned around his argument proposing that, rather than revolutionary, biotechnology is more a “substitutionist” technological form to be applied to declining sectors of the economy than an “epoch-making” technology. This paper provides both external and internal critiques of Buttel's new position based on the concept of the “third technological revolution,” looking at the impact of new technologies as a global and interrelated phenomenon, and not on an individual case-by-case basis. The concluding section suggests the necessity of bringing into the analysis those living in the Third World: 60% of this population lives from agriculture and will be affected by the deployment of agricultural biotechnologies, whether through “substitutionism” or through totally new products.
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  • 39
    ISSN: 1573-5060
    Keywords: Potato ; protein-DNA-binding ; SDS PAGE ; Solanum tuberosum ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Phenotypic variation, SDS-PAGE and protein-DNA binding were used to determine variation during the in vitro phase of potato plantlets derived from callus and cell suspensions. Of the 27 plantlets assessed. 3 displayed a low or abnormal growth, 16 normal growth which correlated well with the original explant and 9 showed strong or vigorous growth. Differences were not observed in the polypeptide profiles of these plantlets. However distinct differences in the protein-DNA-binding profiles occurred which correlated well with the phenotypic variation observed.
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  • 40
    ISSN: 1573-5060
    Keywords: Solanum tuberosum ; potato ; Phytophthora infestans ; late blight ; adventitious regeneration ; somaclonal variation ; tissue culture ; mutation ; maturity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Adventitious regenerants (‘somaclones’) of ‘Bintje’ and their vegetative progeny were screened for field resistance to Phytophthora infestans as follows: the area under the disease progress curve was computed and correlated with resistance rating in ‘Bintje’ and reference varieties. The resistance rating of the somaclones was determined from this relationship. Clones with stable improved field resistance in successive years' trials were detected, however, most of such clones were also maturation mutants. Variation in resistance rating in clone replicates and between years was detected in most clones. The possible basis of the field resistance and reasons for its instability are discussed.
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  • 41
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    Euphytica 56 (1991), S. 269-285 
    ISSN: 1573-5060
    Keywords: disease resistance ; in vitro selection ; somaclonal variation ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Somaclonal variation, i.e. the variation induced by cell and tissue culture, offers an opportunity to broaden the genetic variation of crops. As a result of somaclonal variation a wide range of plant characteristics can be altered. However, the selection of agronomically important traits, e.g. disease resistance, has many limitations. The efficiency of selection can be increased by the application of in vitro selection procedures. Selection strategies that may be applied to obtain disease resistant somaclonal variants are described. Their merits and limitations, in relation to the efficiency of the procedures, the frequency of disease resistant variants and the genetics of the resistance obtained, are discussed.
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  • 42
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    European journal of epidemiology 7 (1991), S. 207-212 
    ISSN: 1573-7284
    Keywords: Rickettsia ; Intracellular parasite ; genetic engineering ; molecular biology ; rickettsial genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Our understanding of the biology of the rickettsiae, organisms that are the archetype of the obligate intracytoplasmic bacterial parasites, remains muddy and fragmentary. For example although we all appreciate that the rickettsiae can exploit their unique environment, the host cell cytoplasm, but are unable to grow axenically, the basis of this fact is still one of microbiology's central mysteries. It is unfortunate, but true, that because of the inherent difficulty of working within this system, progress on the answers to such questions will be slow and laborious. However, with the application of molecular biological methods, that is, the powerful modern approaches of genetics and biochemistry, the rickettsiology community has the realistic prospect that this field is far from being at a stand-still and that significant increases in our comprehension of the fundamental problems of rickettsial biology are occurring and will continue to occur at ever accelerating rates. Some examples, both in terms of scientific conclusions and technical approaches, of the progress made in recent years and expectations for the near future will be presented.
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  • 43
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    Plant cell, tissue and organ culture 25 (1991), S. 27-33 
    ISSN: 1573-5044
    Keywords: cytology ; leaf explants ; Lotus corniculatus ; protoplasts ; regeneration ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regenerants from three types of tissue, leaf explants (132 plants), leaf protoplasts (68 plants) and cotyledonary protoplasts (119 plants) of L. corniculatus cv Leo differed both morphologically and cytologically from control plants grown from seed. Four categories of chromosome number were found. The frequency and type of variation found in the chromosome numbers of regenerants reflected the method of plant regeneration. Regenerants with both normal and abnormal numbers of chromosomes produced progeny which were cytologically normal and showed only minor morphological changes when compared with control plants.
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  • 44
    ISSN: 1573-5060
    Keywords: Fusarium resistance ; Fusarium spp. ; wheat ; Triticum aestivum ; double-layer technique ; in vitro selection ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Calluses of spring and winter wheats (Triticum aestivum L.) were selected for Fusarium resistance in vitro, using the double-layer culture technique. Potato-dextrose agar medium in vials was inoculated with mycelia of Fusarium graminearum and F. culmorum. After one week, fungal cells were killed by autoclaving and the agar medium containing the thermostable toxic metabolites was overlayered with MS callus-growing medium. Later, wheat calluses were placed on the upper medium for 4–5 weeks, and from the surviving calluses plants were regenerated. R2 seedling populations from self-fertilized R1 plants of 4 varieties were tested for Fusarium resistance by artificial infections in the greenhouse, and 3% of the regenerated R2 plants have been found to be more resistant than the original cultivars.
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  • 45
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 296-303 
    ISSN: 0006-3592
    Keywords: ethanol ; genetic engineering ; Escherichia coli ; lignocellulose ; xylose ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The conversion of xylose to ethanol by recombinant Escherichia coli has been investigated in pH-controlled batch fermentations. Chemical and environmental parameters were varied to determine tolerance and to define optimal conditions. Relatively high concentrations of ethanol (56 g/L) were produced from xylose with excellent efficiencies. Volumetric productivities of up to 1.4 g ethanol/L h were obtained. Productivities, yields, and final ethanol concentrations achieved from xylose with recombinant E. coli exceeded the reported values with other organisms. In addition to xylose, all other sugar constituents of biomass (glucose, mannose, arabinose, and galactose) were efficiently converted to ethanol by recombinant E. coli. Unusually low inocula equivalent to 0.033 mg of dry cell weight/L were adequate for batch fermentations. The addition of small amounts of calcium, magnesium, and ferrous ions stimulated fermentation. The inhibitory effects of toxic compounds (salts, furfural, and acetate) which are present in hemicellulose hydrolysates were also examined.
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  • 46
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    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 45 (1991), S. 261-267 
    ISSN: 0730-2312
    Keywords: tissue transplantation ; catecholamines ; dopamine ; L-DOPA ; genetic engineering ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: In animal models, grafts derived from several different tissues, principally fetal substantia nigra and adrenal medulla from young adults, have been found to be effective in alleviating some of the manifestations of lesions of the substantia nigra. It has been suggested that these grafts function by diffusely secreting dopamine, by exerting trophic effects on the host brain, or by producing a new innervation of the host corpus striatum. Evidence for each of these modes of action is briefly reviewed. Several brain tissue transplantation techniques have been described. Each of these techniques has significant limitations in animal models. The significance of these limitations for human application is described, and possibilities for improving the efficacy of brain tissue transplantation in animal models and for human application are discussed.
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  • 47
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    Journal of Cellular Biochemistry 45 (1991), S. 268-272 
    ISSN: 0730-2312
    Keywords: hematopoiesis ; stem cell ; perfusion ; hematopoietic growth factor ; genetic engineering ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The successful ex vivo reconstruction of human bone marrow is an extraordinarily important basic scientific and clinical goal. Fundamentally, the system is the paradigm of a complex interactive tissue, in which the proliferation and regulated differentiation of one parenchymal cell type (the hematopoietic stem cell) is governed by the surrounding stromal cells. Understanding and reproducing the molecular interactions between bone marrow stromal cells and stem cells in tissue culture models is therefore the critical step in successful bone marrow tissue culture. Clinically, successful reconstruction of human bone marrow would permit the controlled production of mature blood cells for transfusion therapy, and immature bone marrow stem cells for bone marrow transplantation. In approaching the bone marrow culture system, we recognize the critical role that hematopoietic growth factors (HGFs) play in hematopoiesis. Since stromal cells in traditional human bone marrow cultures produce little HGFs, we have begun by asking whether local supplementation of hematopoietic growth factors via genetically engineered stromal cells might augment hematopoiesis in liquid cultures. The results indicate that locally produced GM-CSF and IL-3 do augment hematopoiesis for several weeks in culture. In combination with geometric and dynamic approaches to reconstructing physiological bone marrow microenvironments, we believe that this approach has promise for reconstructing human bone marrow ex vivo, thereby permitting its application to a variety of basic and clinical problems.
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  • 48
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    Journal of agricultural and environmental ethics 3 (1990), S. 114-146 
    ISSN: 1573-322X
    Keywords: genetic engineering ; herbicide resistance ; herbicide tolerant crops ; agricultural ethics ; morality ; values ; justice ; sustainable agriculture ; alternative agriculture ; socio-economic effects ; weeds ; biotechnology ; agribusiness ; family farms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract Should we continue to support publicly funded research on genetically engineered herbicide resistant crops? In Part One, I discussed the difference between science and ethics, presented a brief history of weed control, and explained three moral principles undergirding my environmentalist perspective. I then argued that unqualified endorsement (E) of the research is unjustified, as is unqualified opposition (O). In Part Two, I argue against qualified endorsement (QE), and for qualified opposition (QO).
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  • 49
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    Plant molecular biology 15 (1990), S. 527-538 
    ISSN: 1573-5028
    Keywords: β-glucuronidase ; CaMV 35S promoter ; genetic engineering ; immunohistochemistry ; Oryza sativa ; transgenic rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cauliflower mosaic virus promoter is commonly used to drive transcription of chimeric genes in transgenic plants, including the cereals. To determine the tissue and cell types of cereal plants that the promoter functions in, transgenic rice plants containing a CaMV 35S promoter/GUS chimeric gene were analyzed for GUS activity. Insertion of a 35S/GUS chimeric gene at low copy number into chromosomal DNA of plants regenerated from electroporated protoplasts was confirmed by gel blot hybridization analysis of uncut and endonuclease-digested DNA. Quantitative measurement showed that GUS activity was some tenfold higher in rice leaves than in tobacco leaves [8] whereas activities obtained for rice roots were similar to those reported for tobacco roots. Histochemical localization of GUS activity confirmed that the CaMV 35S promoter functions in cells of the leaf epidermis, mesophyll and vascular bundle. It is also active in the cortex and vascular cylinder of the root, but only marginally active in the root epidermis. The generally similar distribution and levels of GUS activity obtained in differentiated tissue of stably transformed rice plants indicates the value of the CaMV 35S promoter as a positive control for studies in gene activity in transgenic monocots and dicots.
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  • 50
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    Plant molecular biology 14 (1990), S. 501-511 
    ISSN: 1573-5028
    Keywords: chloroplast SOD ; paraquat ; stress ; genetic engineering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The petunia nuclear gene which encodes the chloroplast isozyme of superoxide dismutase, SOD-1, has been fused with an efficient rbcS promoter fragment and 3′ flanking region and introduced into tobacco and tomato cells. Transformed plants carrying this chimeric gene have up to 50-fold the levels of SOD-1 which occur in wild-type plants. However, tobacco plants with 30-to 50-fold the normal SOD-1 activity do not exhibit resistance to the light-activated herbicide paraquat. Similarly, tomato plants with 2-to 4-fold increases in SOD-1 do not exhibit tolerance to photoinhibitory conditions known to increase superoxide levels (high light, low temperatures and low CO2 concentrations). Our data indicate that increasing the chloroplastic SOD level in a plant cell is not sufficient to reduce the toxicity of superoxide.
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  • 51
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    Euphytica 51 (1990), S. 249-256 
    ISSN: 1573-5060
    Keywords: Festuca arundinacea ; tall fescue ; chromosome pairing ; electrophoresis ; isoenzyme ; meiotic analyses ; somaclonal variation ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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.
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  • 52
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    Euphytica 46 (1990), S. 35-41 
    ISSN: 1573-5060
    Keywords: forage legumes ; Lotus corniculatus ; birdsfoot trefoil ; somaclonal variation ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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.
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  • 53
    ISSN: 1573-5060
    Keywords: Brassica juncea ; Indian mustard ; in vitro selection ; salt-tolerance ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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.
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  • 54
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    Hydrobiologia 204-205 (1990), S. 151-159 
    ISSN: 1573-5117
    Keywords: Enteromorpha ; genetic engineering ; micro spectrophotometry ; parasexual fusion ; seaweeds ; Ulvaria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Enteromorpha linza and Ulvaria oxysperma in North Carolina reproduce exclusively by asexual zoospores. Calcofluor white staining indicated that newly released zoospores lack significant cellulose cell wall material, making them suitable for treatment as protoplasts in a parasexual fusion process using high pH-Ca2+, PEG and centrifugation. Presumptive fusion products were identified by their larger size, twin chloroplasts and eyespots, and presence of fluorescence labelled and unlabelled portions. Parasexual fusion and karyogamy were confirmed by elevated levels of nuclear DNA in fusion cell germlings. In addition, aceto-orcein staining of fusion cell products revealed a diploid chromosome complement of 2N = 20 in Enteromorpha linza. Fusion cells were isolated by killing the more numerous adjacent unfused zoospores with 2-3 min exposure to blue light (410–490 nm). Unexposed fusion cells could be readily distinguished and recovered by micropipette at the 10-day stage.
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  • 55
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    Plant cell, tissue and organ culture 23 (1990), S. 39-44 
    ISSN: 1573-5044
    Keywords: albino ; aspen ; chimera ; callus culture ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
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  • 56
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    Theoretical medicine and bioethics 11 (1990), S. 103-110 
    ISSN: 1573-1200
    Keywords: genetic engineering ; human embryos ; medical ethics ; medical technology ; in vitro fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Philosophy
    Notes: Abstract In this paper I will discuss three areas in which advances in human reproductive technology could occur, their uses and abuses, and their effects on society. First is the potential to drastically increase the success rate and availability of in vitro fertilization and embryo freezing. Second is the ability to perform biopsies on embryos prior to the onset of pregnancy. Finally, I will consider the adding or altering of genes in embryos, commonly referred to as “genetic engineering”. As new reproductive technologies pass from experimental models into the potential for medical utilization, I believe that it will be important for lawmakers everywhere to avoid the impulse to outlaw procedures that a society believes to be ‘unnatural’ at a first glance. Rather, I would hope that they can respond thoughtfully with legislation that serves two purposes — to protect the rights of couples to overcome infertility or to reduce the risk of genetic disease in their children-to-be, and more importantly, to protect children-to-be from the abuses that could result from some of the practices that I will discuss.
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  • 57
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    Euphytica 85 (1955), S. 295-302 
    ISSN: 1573-5060
    Keywords: tissue culture ; somaclonal variation ; plant breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Somaclonal variation is a tool that can be used by plant breeders. The review examines where this tool can be applied most effectively and the factors that limit or improve its chances of success. The main factors that influence the variation generated from tissue culture are (1) the degree of departure from organised growth, (2) the genotype, (3) growth regulators and (4) tissue source. Despite an increasing understanding of how these factors work it is still not possible to predict the outcome of a somaclonal breeding programme. New varieties have been produced by somaclonal variation, but in a large number of cases improved variants have not been selected because (1) the variation was all negative, (2) positive changes were also altered in negative ways, (3) the changes were not novel, or (4) the changes were not stable after selfing or crossing. Somaclonal variation is cheaper than other methods of genetic manipulation. At the present time, it is also more universally applicable and does not require ‘containment’ procedures. It has been most successful in crops with limited genetic systems and/or narrow genetic bases, where it can provide a rapid source of variability for crop improvement.
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  • 58
    ISSN: 1573-5060
    Keywords: doubled haploids ; micropropagation ; mutant cultivars ; mutation techniques ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Conventional mutation techniques have often been used to improve yield, quality, disease and pest resistance in crops, or to increase the attractiveness of flowers and ornamental plants. More than 1700 mutant varieties involving 154 plant species have been officially released. In some economically important crops, e.g. barley, durum wheat and cotton, mutant varieties occupy the majority of cultivated areas in many countries. Mutation techniques have become one of the major tools in the breeding of ornamentals such as alstroemeria, begonia, chrysanthemum, carnation, dahlia and streptocarpus. The use of in vitro techniques such as anther culture, shoot organogenesis, somatic embryogenesis and protoplast fusion can overcome some of the limitations in the application of mutation techniques in both seed and vegetatively propagated crops. In vitro culture in combination with induced mutations can speed up breeding programmes, from the generation of variability, through selection, to multiplication of the desired genotypes. The expression of induced mutations in the pure homozygote obtained through microspore, anther or ovary culture, can enhance the rapid recovery of the desired traits. In some vegetatively propagated species, mutations in combination with in vitro culture technique, may be the only method of improving an existing cultivar. Currently, many molecular studies rely on the induction and identification of mutants in ‘model species’ for construction and subsequent saturation of genetic maps, understanding of developmental genetics and elucidation of biochemical pathways. Once identified and isolated, the genes that encode agronomically-important features can be either introduced directly into crop plants or used as probes to search for similar genes in crop species. It seems most likely that the recent developments based on these technologies will soon provide improved methods for selection of desired mutants.
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  • 59
    ISSN: 1573-5060
    Keywords: aluminium toxicity ; soil acidity ; somaclonal variation ; sorghum ; Sorghum bicolor (L.) Moench ; tissue culture ; salt stress ; drought stress ; variants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Sorghum bicolor (L.) Moench is generally quite sensitive to salt and acid (high aluminium) soil stresses, but quite tolerant of drought stress. As with any stress phenomenon, intra-specific variability exists within the genus. In vitro cell selection and somaclonal variation offer an alternative to traditional breeding methodology for generating improved breeding lines for hybrid development. A field selection protocol was developed for the three soil stresses and inter-stress evaluations were conducted in an effort to find multiple, stress-tolerant genotypes. The acid soil-drought stress, super-tolerant selections were located by the R7 generation when exposed to a combined aluminium-drought stress field environment and when the regeneration population (number of regenerated lines from one callus source) was maintained at 15,000 plants or higher. A variant frequency of 0.1 to 0.2% for stress tolerance and acceptable agronomic traits among the surviving somaclones, provided an adequate number of phenotypes with desirable agronomic characteristics and a high level of soil stress tolerance. Subsequent research verified that the stress-tolerant regenerants had superior acid soil and drought stress tolerance to that of the donor parents, that their yield capabilities under stress were superior to their parents, and that their stress tolerance attributes were transferred in hybrid combinations. In vitro selection was not effective in increasing the number of field stress survivors. In fact, superior germplasms were developed from non-stressed callus or salt-stressed callus. In vitro selection reduced regeneration frequency and subsequent survival of plants under field stress. In vitro-stressed regenerants should be subjected only to non-stressed environments to maintain population numbers for field selection and thereafter should be subjected to stress environments during later (R5+) generations. The optimal strategy for the exploitation of somaclonal variation may be through short-term cell culture (〈 12 months) with no attempt at in vitro selection.
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  • 60
    ISSN: 1573-5060
    Keywords: Oryza sativa ; Indica-type rice ; genetic engineering ; vitamin A endosperm ; insect resistance ; virus resistance ; fungus resistance ; essential amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Indica-type rice provides the staple food for two billion people in Third World countries. Several problems involved in the stable and sustained production of high quality food cannot be solved by traditional breeding. Methods have been established for gene transfer to Indica rice breeding lines to study possible contributions from genetic engineering. Experiments are in progress on the development of transgenic resistance towards Yellow Stem Borer, resistance towards Rice Tungro Virus, accumulation of provitamin A in the endosperm, increase of essential amino acids in the endosperm such as lysine, cysteine and methionine and resistance towards fungal pests such as Rice Blast and Sheath Blight. Transgenic clones from Indica rice breeding lines have been recovered from several of the approaches mentioned, some of which have been regenerated to plants.
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  • 61
    ISSN: 1573-5060
    Keywords: genetic engineering ; introgression ; molecular markers ; potatoes ; resistances ; Solanum ; technology mansfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potato genetic improvement has been facilitated using new knowledge of potato reproductive biology and new techniques. Many wild diploid species as well as landrace cultivars have been used in breeding at the diploid level, a strategy which is supported by 1) 2n gametes and 2) haploids from tetraploid cultivars. Different categories of wild species which have been under-utilized are now being exploited further in more systematic enhancement programmes using semi-conventional and biotechnological methods. Molecular maps of the potato genome are used actively to achieve marker-assisted introgression and improved selection among the germplasm collections to facilitate the use of valuable wild genetic resources. As an alternative method to incorporate a high level of fesistance, genetic engineering has been employed to facilitate the initial breeding process using various gene constructs for controlling major biotic stresses in the world.
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  • 62
    ISSN: 1573-5060
    Keywords: callus culture ; organogenesis ; pea ; Pisum sativum ; somaclonal variation ; somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The possibility of producing agronomically-useful somaclones via organogenesis and somatic embryogenesis from callus cultures of pea (Pisum sativum L.) was studied. Organogenic calli were induced from immature leaflets on MSB medium with NAA and BAP. Embryogenic calli were derived either from immature zygotic embryos (using 2,4-D) or from shoot apices (using picloram) of aseptically-germinated seedlings. The seed progenies (T1 to T3-generation) of primary regenerants were grown in field conditions and their phenotypic variation was evaluated and compared with control, non-tissue culture-derived plant material. In addition, electrophoretic analyses of selected isoenzyme systems and total proteins have been done. The results do not show dramatic changes in qualitative and quantitative traits. The evaluation of at least two future generations (T4, T5) is planned.
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  • 63
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    Euphytica 85 (1955), S. 1-12 
    ISSN: 1573-5060
    Keywords: genetic engineering ; gene targets ; mapping ; markers ; transformation ; QTLs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 64
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    Euphytica 85 (1955), S. 323-327 
    ISSN: 1573-5060
    Keywords: Brassica napus ; fatty acids ; gas chromatography ; Lunaria annua ; protoplast regeneration ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A programme of research was designed to investigate methods for the modification of the fatty acid profiles of high performance lines of oilseed rape (Brassica napus L.) in an attempt to produce lines with enhanced levels of industrially useful fatty acids. The methodology employed to achieve these objectives was based on the exploitation of somaclonal or protoclonal variation, and targeted somatic hybridization using wild cruciferous germplasm as fusion partners. A range of somaclonal lines was produced from shoot regeneration protocols. These lines underwent replicated, randomised glasshouse trials for morphological assessment followed by gas chromatographic analysis to monitor any changes in fatty acid profile. It was found that a small number of lines exhibited potentially useful changes in oleic acid and polyunsaturated fatty acid content. Protoplast regeneration and electrofusion protocols for a range of winter oilseed rape lines were developed, and methods for the isolation and fusion of protoplasts of the wild crucifer Lunaria annua (chosen for its high nervonic acid content) established.
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  • 65
    ISSN: 1573-5060
    Keywords: Linum usitatissimum ; linseed ; mutation breeding ; somaclonal variation ; fatty acids ; genetic engineering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In the early 1980s the phenomenon of somaclonal variation induced by cell culture was exploited to produce genetic variation in linseed. The linseed variety Andro, derived from the widely grown Canadian variety McGregor, was selected in saline culture and was released for production in Canada. ‘Andro’ possesses traits very different from its parent, such as increased seedling vigour and tolerance to heat stress. Additional stable somaclonal variation in characters such as yield, days to maturity, seed weight and oil content were subsequently induced in ‘McGregor’. However, despite extensive screening of the somaclonal variants, no significant variation in the fatty acid profile was found. Chemical mutagenesis using ethyl methanesulphonate was, however, succesful in modifying the fatty acid profile of McGregor. Initial screening of M2 seed by the thiobarbituric acid colourimetric procedure was followed by gas chromatography to select half-seeds with atypical fatty acid profiles. Two independent, partially dominant genes were identified that were responsible for reducing the linolenic acid (18 : 3) from 50% to 2% while increasing linoleic acid (18 : 2) to 70%. A single, partially dominant gene, inherited independently of the linolenic acid genes, increased palmitic acid (16 : 0) from 7% to 30% and palmitoleic acid (16 : 1) from trace amounts to 4%. Agrobacterium-mediated transformation of linseed has also been successful. Herbicide tolerance genes for glyphosate, sulfonylurea and phosphinothricin have been incorporated into Canadian varieties. Commercially useful levels of tolerance to sulfonylurea herbicides have been achieved with no adverse agronomic affect. It is expected that a transgenic variety containing this resistance will be registered for commercial production in Canada in 1994. Standard breeding techniques, the application of antisense technology and the overexpression of fatty acid synthesis genes are being used to further modify the fatty acid profile of linseed, as well as for the transfer of abiotic stress-related genes identified in bromegrass.
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