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  • Articles: DFG German National Licenses  (369)
  • Agrobacterium
  • genetic engineering
  • particle bombardment
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  • Articles: DFG German National Licenses  (369)
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  • 1
    ISSN: 1432-203X
    Keywords: Key words Chickpea ; Transformation ; Agrobacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Embryo axes of four accessions of chickpea (Cicer arietinum L.) were treated with Agrobacterium tumefaciens strains C58C1/GV2260 carrying the plasmid p35SGUSINT and EHA101 harbouring the plasmid pIBGUS. In both vectors the GUS gene is interrupted by an intron. After inoculation shoot formation was promoted on MS medium containing 0.5 mg/l BAP under a selection pressure of 100 mg/l kanamycin or 10 mg/l phosphinothricin, depending on the construct used for transformation. Expression of the chimeric GUS gene was confirmed by histochemical localization of GUS activity in regenerated shoots. Resistant shoots were grafted onto 5-day-old dark-grown seedlings, and mature plants could be recovered. T-DNA integration was confirmed by Southern analysis by random selection of putative transformants. The analysis of 4 plantlets of the T1 progeny revealed that none of them was GUS-positive, whereas the presence of the nptII gene could be detected by polymerase chain reaction.
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  • 2
    ISSN: 1432-203X
    Keywords: Key words Poplar ; Populus ; Aspen ; Cottonwood ; Transformation ; Agrobacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We describe a protocol for Agrobacterium tumefaciens-mediated transformation of hybrid cottonwoods (Populus sections Tacamahaca Spach. and Aigeiros Duby). The protocol has allowed routine transformation of several economically important cottonwood hybrids (Populus trichocarpa Torr. & Gray×P. deltoides Bartr. ex. Marsh. and P. deltoides×P. nigra L.) that were previously difficult to transform. The procedure was applied to 11 different hybrid cottonwood genotypes and one P. deltoides genotype using kanamycin as the selection agent. Additional experiments showed a very strong interaction between auxin preculture and the effectiveness of various cytokinins for induction of shoot organogenesis. The data also demonstrated the superiority of Agrobacterium strain EHA105 over C58 and LBA4404 for T-DNA transfer based on transient assays with a reporter gene.
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  • 3
    ISSN: 1432-203X
    Keywords: Key words Allium cepa ; Transformation ; Regeneration ; gfp gene ; Agrobacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  An Agrobacterium tumefaciens-mediated transformation method has been developed for onions (Allium cepa L.) using immature embryos as the explant source. Transgenic plants were recovered from the open-pollinated onion cultivar Canterbury Longkeeper at a maximum transformation frequency from immature embryos of 2.7%. The method takes between 3–5 months from explant to primary regenerant entering the glasshouse. Multiple-shoot formation from primary transgenic material made possible the clonal multiplication of transformants. The binary vector used carried the nptII antibiotic resistance gene and the m-gfp5-ER reporter gene. Transgenic cultures were initially screened for their ability to fluoresce and to grow in the presence of geneticin (5–25 mg/l). The transgenic nature of individual plants was confirmed by Southern blot analysis.
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  • 4
    ISSN: 1573-9368
    Keywords: Hyoscyamus muticus ; particle bombardment ; transformation ; tropane alkaloids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report an efficient whole plant transformation system for Hyoscyamus muticus, an important medicinal plant of the Solanaceous family. We developed a system using a plasmid carrying the nptII and gusA genes, which was delivered into leaf explants by particle bombardment. Ten percent of bombarded leaf explants formed kanamycin-resistant callus, from which putative transgenic plants were recovered. The nptII gene conferring kanamycin resistance was found to be incorporated into the genome of all transgenic plants screened. Over 50% of the kanamycin resistant plants showed strong expression of the non-selected gusA gene. The majority of transgenic plants reached maturity, could be self pollinated, and produced fertile seed. A simple and efficient whole plant transformation system for this medicinal plant is an important step in furthering our understanding of tropane alkaloid production in plants.
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  • 5
    ISSN: 1573-9368
    Keywords: direct transformation ; haploid plant ; Marchantia polymorpha ; particle bombardment ; plant regeneration ; stable integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thalli of the haploid liverwort Marchantia polymorpha were successfully used for direct particle bombardment with plasmid pMT, which carries a hygromycin phosphotransferase gene (hpt) controlled by the CaMV 35S promoter and the NOS polyadenylation region. Hygromycin-resistant cell masses arose from the thallus surface and developed directly into hygromycin-resistant thalli. Southern blot analyses indicated that these thalli carried at least 1–4 copies of the hpt gene, which were stably transmitted to their asexual thallus progenies via gemma propagation for three generations. This transformation and direct plant regeneration protocol is expected to be a valuable tool for the molecular analysis of this lower land plant.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    International journal of technology and design education 10 (2000), S. 239-254 
    ISSN: 1573-1804
    Keywords: contexts ; critical reflection ; environment ; ethics ; genetic engineering ; impacts ; values
    Source: Springer Online Journal Archives 1860-2000
    Topics: Art History , Education , Technology
    Notes: Abstract Design and technology education aims to prepare young people for living in a rapidly changing technological society which will involve them in making many value judgements, some with complex ethical dimensions. Key aspects of the ethical judgements in relation to genetic engineering are examined: the hidden assumptions, the inevitable unpredictability when dealing with living processes highly interactive with the surroundings, the commercial and political pressures, and the underlying `world-views' and values. It is argued that responsible judgements therefore require wide consultation, sensitivity to social, cultural and moral issues, acknowledgement of the political and economic context, and above all, critical reflection on the beliefs and commitments that are shaping the vision and the drive. Teaching and learning strategies are needed that highlight the social and environmental context of technological activity, that encourage pupils to consider what determines the quality of their own lives and those of others, and that stimulates reflection on the values and beliefs which influence the priorities when value judgements are being made.
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  • 7
    ISSN: 1572-9788
    Keywords: cotransformation ; gna gene ; insect resistance ; Oryza sativa L. ; particle bombardment ; transgenic Thai rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We used particle bombardment to transform two elite Thai rice varieties, Khao Dawk Mali 105 (KDML105) and Supanburi 60 (SP60), with the snowdrop lectin gene gna (Galanthus nivalis agglutinin). This gene confers resistance to sap-sucking insects such as the brown planthopper (BPH; Nilaparvata lugens), which is one of the most damaging pests of rice. Traditionally, KDML105 and SP60 have been regarded as recalcitrant to transformation, and this is the first account of successful gene transfer to these varieties. By molecular analysis, we confirmed the recovery of over thirty gna-transgenic lines. GNA protein expression was characterised by western blot analysis, and we achieved expression levels of up to 0.25% total soluble protein. GNA-producing R1 transgenic plants were significantly more resistant to BPH than control plants (P〈0.0001), with 37% and 42% reduction in nymphal survival for constitutive and phloem-specific expression, respectively. Transferring the gna gene to these superior rice varieties thus represents a major step forward for crop improvement in Thailand, and should help to reduce the damage caused by rice pests, and hence increase yields for this vital domestic and export market.
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  • 8
    ISSN: 1572-9788
    Keywords: Agrobacterium ; inheritance analysis ; Lavandula latifolia ; lavender ; organogenesis ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Transgenic plants of the aromatic shrub Lavandula latifolia (Lamiaceae) were produced using Agrobacterium tumefaciens-mediated gene transfer. Leaf and hypocotyl explants from 35–40-day old lavender seedlings were inoculated with the EHA105 strain carrying the nptII gene, as selectable marker, and the reporter gusA gene with an intron. Some of the factors influencing T-DNA transfer to L. latifolia explants were assessed. Optimal transformation rates (6.0 ± 1.6% in three different experiments) were obtained when leaf explants precultured for 1 day on regeneration medium were subcultured on selection medium after a 24 h co-cultivation with Agrobacterium. Evidence for stable integration was obtained by GUS assay, PCR and Southern hybridisation. More than 250 transgenic plants were obtained from 37 independent transformation events. Twenty-four transgenic plants from 7 of those events were successfully established in soil. β-glucuronidase activity and kanamycin resistance assays in greenhouse-grown plants from two independent transgenic lines confirmed the stable expression of both gusA and nptII genes two years after the initial transformation. Evidence from PCR data, GUS assays and regeneration in the presence of kanamycin demonstrated a 1:15 Mendelian segregation of both transgenes among seedlings of the T1 progeny of two plants from one transgenic L. latifolia line.
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  • 9
    Electronic Resource
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    Springer
    Molecular breeding 6 (2000), S. 185-194 
    ISSN: 1572-9788
    Keywords: Agrobacterium ; transformation ; pea ; Pisum sativum L. ; PCR analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Factors influencing the efficiency of Agrobacterium-mediated transformation of pea were tested using highly efficient, direct regeneration system. The virulence of three Agrobacterium strains (octopine LBA 4404, nopaline C58C1 and succinamopine, hypervirulent EHA 105) clearly varied giving 1 transgenic plant per 100 explants for LBA 4404, 2.2 for C58C1 and 8.2 for EHA 105. To test the efficacy of selection agents we used the hypervirulent EHA 105 strain carrying pGPTV binary vector with one of four different selection genes: nptII, hpt, dhfr or bar. The mean number of transgenic, kanamycin-resistant plants for two cultivars tested was 4.2 per 100 explants and was slightly higher than the number of phosphinothricin-resistant plants (3.6 plants per 100 explants). The proportion of transgenics among kanamycin-selected plants was also higher than among phosphinothricin-resistant plants (35% and 28% respectively). There was no regeneration on hygromycin or methotrexate media (transformation with hpt and dhfr genes). Acetosyringone had no apparent influence on efficiency of transformation with hypervirulent EHA 105 strain, however it did affect the rate of transformation when moderately virulent C58C1 was used. Recovery of transgenic plants was enhanced after application of 5-azacytidine. The presence of integrated T-DNA was checked by PCR and confirmed by Southern hybridization. T-DNA was stably transmitted to the next generation.
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  • 10
    ISSN: 1573-5028
    Keywords: transgenic cereals ; molecular pharming ; antibodies ; carcinoembryonic antigen ; single-chain Fv fragment ; particle bombardment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This report describes the stable expression of a medically important antibody in the staple cereal crops rice and wheat. We successfully expressed a single-chain Fv antibody (ScFvT84.66) against carcinoembryonic antigen (CEA), a well characterized tumor-associated marker antigen. scFv constructs were engineered for recombinant antibody targeting to the plant cell apoplast and ER. Up to 30 μg/g of functional recombinant antibody was detected in the leaves and seeds of wheat and rice. We confirmed that transgenic dry seeds could be stored for at least five months at room temperature, without significant loss of the amount or activity of scFvT84.66. Our results represent the first transition from model plant expression systems, such as tobacco and Arabidopsis, to widely cultivated cereal crops, such as rice and wheat, for expression of an antibody molecule that has already shown efficacy in clinical applications. Thus, we have established that molecular pharming in cereals can be a viable production system for such high-value pharmaceutical macromolecules. Our findings provide a strong foundation for exploiting alternative uses of cereal crops both in industrialized and developing countries.
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  • 11
    ISSN: 1573-5028
    Keywords: Agrobacterium ; binary vectors ; plant transformation ; reporter genes ; selectable marker genes ; Ti vector
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Binary Ti vectors are the plasmid vectors of choice in Agrobacterium-mediated plant transformation protocols. The pGreen series of binary Ti vectors are configured for ease-of-use and to meet the demands of a wide range of transformation procedures for many plant species. This plasmid system allows any arrangement of selectable marker and reporter gene at the right and left T-DNA borders without compromising the choice of restriction sites for cloning, since the pGreen cloning sites are based on the well-known pBluescript general vector plasmids. Its size and copy number in Escherichia coli offers increased efficiencies in routine in vitro recombination procedures. pGreen can replicate in Agrobacterium only if another plasmid, pSoup, is co-resident in the same strain. pSoup provides replication functions in trans for pGreen. The removal of RepA and Mob functions has enabled the size of pGreen to be kept to a minimum. Versions of pGreen have been used to transform several plant species with the same efficiencies as other binary Ti vectors. Information on the pGreen plasmid system is supplemented by an Internet site (http://www.pgreen.ac.uk) through which comprehensive information, protocols, order forms and lists of different pGreen marker gene permutations can be found.
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  • 12
    ISSN: 1572-994X
    Keywords: plant viral promoter ; caulimovirus ; strawberry vein banding virus ; zucchini yellow mosaic virus ; particle bombardment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A putative promoter from the strawberry vein banding caulimovirus (SVBV) genome was identified by its ability to drive infection with full-length cDNA of the zucchini yellow mosaic RNA potyvirus (ZYMV). A high rate of infection was obtained with the cDNA under control of the SVBV promoter using particle bombardment technology. The SVBV promoter shows 60% homology to the cauliflower mosaic virus 35S promoter in the domain spanning the conserved motifs of CCACT (at −83) and the TATA box (at −31), to the transcription start. The 3′-end one-third of the putative promoter (328 bp) was sufficient to invoke full infectivity with the ZYMV clone, and drove transient reporter gene expression in Solanaceae and Cucurbitaceae transformed with a binary plant transformation vector. Stable expression of a reporter gene (GUS) under control of the truncated SVBV promoter was shown in transformed tobacco shoots in roots, leaves and stems.
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  • 13
    Electronic Resource
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    Springer
    Plant cell, tissue and organ culture 62 (2000), S. 141-151 
    ISSN: 1573-5044
    Keywords: Agrobacterium ; forage quality ; KDEL ; recombinant proteins ; sulphur-rich amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Accumulation of zeins, the endosperm storage proteins of maize, in a heterologous plant expression system was attempted. Plants of Nicotiana tabacum and Lotus corniculatus were transformed by Agrobacterium with binary vectors harbouring genes that code for γ-zein and β-zein, two zeins rich in sulphur amino acids. Adding the ER retention signal KDEL to the C-terminal domain modified the zein polypeptides. Significant levels of γ-zein:KDEL and β-zein:KDEL were detected in primary transformants of tobacco. Moreover, the two zeins colocalized in leaf protein bodies of γ-/β-zein:KDEL plants derived from a cross between two primary transformants. Coexpression of γ-zein:KDEL and β-zein:KDEL could be a useful strategy to obtain genotypes of forage legumes which are able to accumulate sulphur amino acids to high levels. As a first step, L. corniculatus plants expressing γ-zein:KDEL in the leaves were obtained.
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  • 14
    ISSN: 1573-5060
    Keywords: Barley ; Hordeum vulgare ; transformation ; particle bombardment ; particle gun
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Immature embryos of the spring barley variety GoldenPromise, were bombarded with three different particledelivery systems and both transient and stabletransformation examined. In addition, a range oftechniques for the preparation of the DNA coated goldparticles was examined. Fertile transgenic barleyplants were obtained using three particle preparationtechniques which differed in the amount of gold andDNA used for each bombardment. However, only one ofthe particle delivery systems, the PDS 1000/He device,appeared to be effective in yielding transformedbarley plants.
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  • 15
    ISSN: 1573-6776
    Keywords: Escherichia coli ; genetic engineering ; metal-binding ; OmpC ; protein engineering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The outer membrane protein, OmpC, from Escherichia coli was used to display metal-binding poly-histidine peptides on the surface of this bacterium. SDS-PAGE analysis of outer membrane protein preparations confirmed the expression of the metal-binding epitopes inserted in position 162 of the mature OmpC protein. Display of these epitopes was confirmed by epifluorescence microscopy of cells bound to Ni2+-NTA-agarose beads and metal adsorption experiments. The cells harboring one or two copies of the metal binding epitope were able to adsorb 3 to 6 times more Zn2+ (13.8 μmol g−1 cell), Fe3+ (35.3 μmol g−1 cell), and Ni2+ (9.9 μmol g−1 cell) metallic ions than control cells expressing the wild-type OmpC.
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  • 16
    ISSN: 1573-6776
    Keywords: bioremediation ; genetic engineering ; heavy metal ; hydrogen sulfide ; thiosulfate reductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The thiosulfate reductase gene (phsABC) from Salmonella typhimuriumwas expressed in Escherichia coliin order to produce sulfide from inorganic thiosulfate and precipitate metals as metal sulfide complexes. The sulfide-engineered strain removed significant amounts of heavy metals from the medium within 24 h: 99% of zinc up to 500 μM, 99% of lead up to 200 μM, 99% of 100 μM and 91% of 200 μM cadmium. In a mixture of 100 μM each of cadmium, lead, and zinc, the strain removed 99% of the total metals from solution within 10 h. Cadmium was removed first, lead second, and zinc last. These results have important implications for removal of metals from wastewater contaminated with several metals.
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  • 17
    Electronic Resource
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    Springer
    Journal of agricultural and environmental ethics 12 (2000), S. 319-330 
    ISSN: 1573-322X
    Keywords: biotechnology ; consumer sovereignty ; genetic engineering ; informed consent ; product labeling ; risk communication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract Recently, both consumers and producers ofbiotechnology products have insisted thatcommunication between the two be improved. The formerdemand more democratic participation in the riskassessment process of biotechnology products. Thelatter seek to correct misinformation regardingalleged risks from these products. One way to resolvethese concerns, I argue, is through the use ofbiotechnology labels. Such labeling fosters consumerautonomy and moves toward more participatory decisionmaking, in addition to ensuring that informed consentfrom consumers is maintained. Furthermore, althoughvoluntary biotech-free labeling in lieu of biotechlabels may uphold consumer sovereignty, the latterremains a more effective strategy for achievingethical communication between consumers and producersof biotechnology products.
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  • 18
    Electronic Resource
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    Springer
    Journal of agricultural and environmental ethics 12 (2000), S. 279-303 
    ISSN: 1573-322X
    Keywords: environment ; genetic engineering ; biotechnology ; pesticides ; agriculture ; pest control ; risks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract Despite the application of 2.5 million tons ofpesticides worldwide, more than 40% of all potentialfood production is lost to insect, weed, and plantpathogen pests prior to harvest. After harvest, anadditional 20% of food is lost to another group ofpests. The use of pesticides for pest control resultsin an estimated 26 million human poisonings, with220,000 fatalities, annually worldwide. In the UnitedStates, the environmental and public health costs forthe recommended use of pesticides total approximately$9 billion/yr. Thus, there is a need for alternativenon-chemical pest controls, and genetic engineering(biotechnology) might help with this need. Diseaseand insect pest resistance to various pests has beenslowly bred into crops for the past 12,000 years;current techniques in biotechnology now offeropportunities to further and more rapidly improve thenon-chemical control of disease and insect pests ofcrops. However, relying on a single factor, like theBacillus thuringiensis toxin that has beeninserted into corn and a few other crops for insectcontrol, leads to various environmental problems,including insect resistance and, in some cases, athreat to beneficial biological control insects andendangered insect species. A major environmental andeconomic cost associated with genetic engineeringapplications in agriculture relates to the use ofherbicide resistant crops (HRC). In general, HRCtechnology results in increased herbicide use but noincrease in crop yields. The heavy use of herbicidesin HRC technology pollutes the environment and canlead to weed control costs for farmers that may be2-fold greater than standard weed control costs. Therefore, pest control with both pesticides andbiotechnology can be improved for effective, safe,economical pest control.
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  • 19
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    Springer
    Journal of agricultural and environmental ethics 13 (2000), S. 313-327 
    ISSN: 1573-322X
    Keywords: Agri-biotech companies ; agriculture ; biotechnology ; existing technologies ; farmers ; farm crisis ; genetic engineering ; hunger ; poverty ; productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract The use of genetic engineering inagriculture has been the source of much debate. Todate, arguments have focused most strongly on thepotential human health risks, the flow of geneticmaterial to related species, and ecologicalconsequences. Little attention appears to have beengiven to a more fundamental concern, namely, who willbe the beneficiaries of this technology? Given the prevalence of chronic hunger and thestark economics of farming, it is arguable thatfarmers and the hungry should be the mainbeneficiaries of agricultural research. However, theapplication of genetic engineering appears unlikely tobenefit either of these two groups. This technology islargely controlled by the private sector, and itscontinued development hinges on its profitability.Thus, the only likely beneficiaries of the applicationof genetic engineering in agriculture are companieswith the capacity to use it.
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  • 20
    Electronic Resource
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    Springer
    Journal of agricultural and environmental ethics 13 (2000), S. 43-51 
    ISSN: 1573-322X
    Keywords: genetic engineering ; inherent value ; moral obligation ; Swiss constitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract The Swiss expert report suggests thatthe inherent dignity of a living being be identifiedwith its inherent value. But the phrase ``inherentvalue of a living being'' seems to connote two conceptsof inherent value. One has a morally obligatingcharacter but is counterintuitive because of itsegalitarianism. The other is one of non-moral value.It is more compatible with considered intuitions butinsufficient for substantiating the expert report'sclaim that human beings have moral duties towardsanimals and plants. The paper discusses theseconcepts. Consideration is then given to the problemof how discursive support can be generated for theexpert report's claim that human beings have the moralduty to abstain from impairing those functions andabilities of a non‐uman being that members of itsspecies as a rule can practice.
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  • 21
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    Journal of agricultural and environmental ethics 13 (2000), S. 29-42 
    ISSN: 1573-322X
    Keywords: dignity of creatures ; genetic engineering ; human dignity ; inherent value ; Swiss Constitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract In their report for the Swiss government onthe notion of the dignity of creatures, PhilippBalzer, Klaus-Peter Rippe, and Peter Schaber analyzethe relationship between human dignity and the dignityof creatures, taking them as two categoricallydifferent concepts. Human dignity is defined as the``moral right not to be humiliated,'' whereas thedignity of creatures is taken to be ``the inherentvalue of non‐human living beings.'' To my mind there isno need to draw a categorical distinction between thetwo concepts. Both notions could be brought togetherunder an all-encompassing concept of the inherentvalue of living beings, humans and non-humans alike,a concept one could name ``the dignity of livingbeings.'' Indeed, this very notion underlies theposition taken in the report, although this is notmade explicit by the authors themselves. As the aim of the paper is only to clarify theconcepts used, I do not go beyond this ``internal''critique of their position, i.e., I don't assess howthe claims articulated via these concepts – theclaim that humans and/or creatures have an inherentvalue consisting in a supposed intrinsic good – areto be justified, although I myself would be ratherskeptical that this might be successfully done.
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  • 22
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    Journal of agricultural and environmental ethics 13 (2000), S. 7-27 
    ISSN: 1573-322X
    Keywords: dignity ; Swiss Constitution ; nonhuman inherent value ; genetic engineering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract The 1992 incorporation of an article by referendum in the SwissConstitution mandating that the federal government issue regulations onthe use of genetic material that take into account the dignity ofnonhuman organism raises philosophical questions about how we shouldunderstand what is meant by ``the dignity of nonhuman animals,'' andabout what sort of moral demands arise from recognizing this dignitywith respect to their genetic engineering. The first step in determiningwhat is meant is to clarify the difference between dignity when appliedto humans and when applied to nonhumans. Several conceptions of humandignity should be rejected in favor of a fourth conception: the rightnot to be degraded. This right implies that those who have it have thecognitive capacities that are prerequisite for self-respect. In the caseof nonhuman organisms that lack this capacity, respecting their dignityrequires the recognition that their inherent value, which is tied totheir abilities to pursue their own good, be respected. This value isnot absolute, as it is in the case of humans, so it does not prohibitbreeding manipulations that make organisms more useful to humans. But itdoes restrict morally how sentient animals can be used. In regard togenetic engineering, this conception requires that animals be allowedthe uninhibited development of species specific functions, a positionshared by Holland and Attfield, as opposed to the Original Purposeconception proposed by Fox and the Integrity of the Genetic Make-upposition proposed by Rolston. The inherent value conception of dignity,as here defended, is what is meant in the Swiss Constitution article.
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  • 23
    ISSN: 1573-9368
    Keywords: particle bombardment ; minimal cassette ; cotransformation ; transgenic rice ; integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Whole plasmids are used in both Agrobacterium-mediated transformation and direct DNA transfer, generally leading to the integration of vector backbone sequences into the host genome along with the transgene(s). This is undesirable, as vector backbone sequences often have negative effects on transgene or endogenous gene expression, and can promote transgene rearrangements. We, therefore, bombarded rice tissue with two constructs: a plasmid containing the bar gene, and a linear DNA fragment isolated from the same plasmid, corresponding to the minimal bar gene expression cassette (promoter, open reading frame and terminator). We recovered phosphinothricin-resistant plants from both experiments, showing that the selectable marker was efficiently expressed. Transformation with such constructs resulted in predominantly 'simple' integration events (one or two bands on Southern blots), producing low-copy-number transgenic plants with a low frequency of transgene rearrangements. Conversely, transformation with supercoiled or linearized whole plasmids generated plants with 'complex' integration patterns, that is, higher copy numbers and frequent transgene rearrangements. We monitored transgenic lines through to the R4 generation and observed no silencing in plants carrying minimal constructs. We also carried out experiments in which rice tissue was simultaneously bombarded with minimal linear hpt and gusA cassettes. We observed robust GUS activity in hygromycin-resistant plants, confirming co-expression of the selectable and nonselectable markers. Furthermore, the efficiency of cotransformation using minimal constructs was the same as that using supercoiled plasmid cointegrate vectors.
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  • 24
    ISSN: 1573-9368
    Keywords: calcium-dependent ; light regulation ; particle bombardment ; protein kinase ; seed development ; transgenic rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Independent transgenic rice lines overexpressing the rice CDPK isoform OsCDPK2 were generated by particle bombardment. High levels of OsCDPK2 were detected in leaves removed from etiolated plants, as well as in stems and flowers. However, there was no overexpression in green leaves that had been exposed to light, confirming that OsCDPK2 protein stability was subject to light regulation. The morphological phenotype of transgenic plants producing high levels of recombinant OsCDPK2 was normal until the onset of seed development. Flowers developed normally, producing well-shaped ovaries and stigmas, and mature anthers filled with pollen grains. However, seed formation in these plants was strongly inhibited, with only 3–7% of the flowers producing seeds. Seed development was arrested at an early stage. We discuss these data with respect to the possible requirement for specific CDPK isoforms during rice seed 4.4ptdevelopment.
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  • 25
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    The journal of ethics 3 (1999), S. 51-71 
    ISSN: 1572-8609
    Keywords: biotechnology ; cloning ; ethics of biotechnology ; ethics of cloning ; ethics of human cloning ; ethics for reproductive technology ; genetic engineering ; human cloning ; religious ethics ; reproductive technology ; secular ethics ; social ethics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Philosophy
    Notes: Abstract The advent of cloning animals has created a maelstrom of social concern about the “ethical issues” associated with the possibility of cloning humans. When the “ethical concerns” are clearly examined, however, many of them turn out to be less matters of rational ethics than knee-jerk emotion, religious bias, or fear of that which is not understood. Three categories of real and spurious ethical concerns are presented and discussed: 1) that cloning is intrinsically wrong, 2) that cloning must lead to bad consequences, and 3) that cloning harms the organism generated. The need for a rational ethical framework for discussing biotechnological advances is presented and defended.
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  • 26
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    Plant molecular biology reporter 17 (1999), S. 323-331 
    ISSN: 1572-9818
    Keywords: Agrobacterium ; modular vector ; transformation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wheat (cv Chinese Spring) tissues were transformed using Agrobacterium tumefasciens and a new plasmid modular vector, pMVTBP. We constructed pMVTBP with unique restriction sites connecting (1) the CaMV 35S promoter, (2) a Kozak sequence, (3) the FLAG epitope, (4) the (His)6 epitope, (5) a coding region (for wheat TATA Binding Protein, wTBP) and (6) the CaMV 35S 3′UTR. This vector thus allows easy exchange of different regulatory or coding sequences. Explants of either germinating mature seeds, or immature embryos, were induced to callus for up to two weeks, treated with virulence-induced bacteria for one hour, then regenerated into plantlets. Transient expression of a GUS reporter gene, assayed at about one week, occurred in 10–12% of calluses. Expression of the FLAG-tagged wTBP was also detected, by immunostaining. Stable expression, by selective growth on geneticin, and by GUS expression at about six weeks, occurred in 1–2% of calluses, quite comparable to that achieved by other methods.
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  • 27
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    Plant cell reports 18 (1999), S. 387-393 
    ISSN: 1432-203X
    Keywords: Key words Almond ; Prunus ; Transformation ; Agrobacterium ; Adventitious regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Almond (Prunus dulcis Mill.) leaves were transformed with the marker genes gusA (β-glucuronidase) and nptII (neomycin phosphotransferase II) via Agrobacterium-mediated transformation. Bacterial strains and preculture of explants affected efficiency of gene transfer evaluated by transient expression assays. Following transformation, shoots were induced from primary explants on medium without kanamycin and exposed to selection 20 days after cocultivation. From 1419 original leaves, four shoots (A, B, C and D) were obtained that showed amplification of the predicted DNA fragments by polymerase chain reaction (PCR). After micropropagation of these shoots, only those cloned from shoot D gave consistently positive results in histochemical GUS detection and PCR amplification. Southern blot hybridisation confirmed stable transgene integration in clone D, which was also negative in PCR amplification of an Agrobacterium gene. Additional molecular analysis suggested that the remaining three shoots (A, B and C) were chimeric.
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  • 28
    ISSN: 1432-203X
    Keywords: Key words Green-fluorescent protein ; Transformation ; Particle bombardment ; Agrobacterium ; Sugarcane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Early detection of plant transformation events is necessary for the rapid establishment and optimization of plant transformation protocols. We have assessed modified versions of the green fluorescent protein (GFP) from Aequorea victoria as early reporters of plant transformation using a dissecting fluorescence microscope with appropriate filters. Gfp-expressing cells from four different plant species (sugarcane, maize, lettuce, and tobacco) were readily distinguished, following either Agrobacterium-mediated or particle bombardment-mediated transformation. The identification of gfp-expressing sugarcane cells allowed for the elimination of a high proportion of non-expressing explants and also enabled visual selection of dividing transgenic cells, an early step in the generation of transgenic organisms. The recovery of transgenic cell clusters was streamlined by the ability to visualize gfp-expressing tissues in vitro.
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  • 29
    ISSN: 1573-9368
    Keywords: low molecular weight glutenin promoter ; particle bombardment ; transgene expression ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transgenic wheat plants from specific cultivars can now be routinely engineered in many laboratories. However, our understanding of the factors controlling transgene expression and stability in wheat compared to other cereals is rather limited. Only a few promoters have been tested in transgenic wheat, and relatively little is known of their relative activities and expression parameters. In the present study, the spatial and temporal properties of one heterologous constitutive promoter and one seed‐specific wheat promoter were investigated. We generated constructs with the reporter gene gusA (β‐glucuronidase) driven by: (a) the constitutive maize ubiquitin‐1 (ubi‐1) promoter, and (b) two different‐sized fragments of the seed‐specific low molecular weight glutenin (LMWG1D1) promoter from wheat. The activities of all three promoter constructs were comparable in endosperm tissue. A detailed analysis of spatial and temporal properties of the promoters is described. Heat shock treatment of transgenic plants carrying the ubi‐1: gusA construct resulted in a significant elevation in the levels of GUS activity. The inheritance of transgene expression levels and stability was evaluated over four generations, as a function of transgene integration patterns and copy number.
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  • 30
    ISSN: 1572-9788
    Keywords: transgenic trees ; scaffold attachment region ; Agrobacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A genetic transformation procedure for white pine has been developed after cocultivation of embryogenic tissues with Agrobacterium tumefaciens. This efficient transformation procedure led to an average of four independent transformed lines per gram of cocultivated embryogenic tissue and up to 50 transformed lines can be obtained in a routine experiment. Constructs bearing the uidA gene or the green fluorescent protein (GFP) gene were introduced and β-glucuronidase (GUS) activity was followed over time. The expression of the uidA gene was lowest with a 35S-gus-intron construct and was 20-fold higher with a 35S-35S-AMVgus::nptII construct. The addition of scaffold attachment region (SAR) sequences surrounding the gus::nptII fusion did not significantly enhance the GUS activity. Transformed mature somatic embryos have been germinated and plantlets are presently being acclimatized.
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  • 31
    ISSN: 1572-9788
    Keywords: transgenic carnation ; genetic engineering ; microprojectile bombardment ; stable transformation ; kanamycin selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Highly efficient Agrobacterium-mediated transformation of carnation (Dianthus caryophyllus L.) was obtained by first wounding stem explants via microprojectile bombardment. When this was followed by cocultivation with disarmed Agrobacterium in the dark, the transformation frequency-based on transient GUS expression-increased to over 10-fold that of explants wounded by other means and cocultivated under constant light. Two cycles of regeneration/selection on kanamycin were employed to generate stably transformed carnation plants and eliminate chimeras: first, plantlets were regenerated from inoculated stem explants and then leaves from these plantlets were used to generate transgenes in a second selection cycle of adventitious shoot regeneration. Agrobacterium strain AGLO, carrying the binary vector pCGN7001 containing uidA and nptII genes, was used in the stable transformation experiments. The combination of wounding via bombardment, cocultivation in the dark and two cycles of kanamycin selection yielded an overall transformation efficiency of 1–2 transgenes per 10 stem explants for the three carnation varieties analyzed. Histochemical and molecular analyses of marker genes in T0 and T1 generations confirmed the transgenic nature of the selected plants.
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  • 32
    ISSN: 1572-9788
    Keywords: Basmati 370 and M7 varieties ; δ-endotoxins (Cry1Ac and Cry2A) ; particle bombardment ; snowdrop lectin (GNA) ; transgenic rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We cotransformed indica rice (Oryza sativa L. cvs. Basmati 370 and M7) with three plasmids, carrying a total of four genes, by particle bombardment. The Bacillus thuringiensis (Bt) δ-endotoxin genes cry1Ac and cry2A were carried on separate vectors, while the gna (snowdrop lectin) and hpt (hygromycin phosphotransferase) genes were linked on the same, cointegrate vector. We evaluated the molecular and expression profiles of 29 independently derived transgenic lines over two generations. The gna and hpt genes cointegrated with a frequency of 100% as expected. Furthermore, 60% of the transgenic plants carried all four genes. Southern blot analysis showed that transgene copy number ranged from 1 to 15. We used western blots to determine protein expression levels in R0 and R1 plants. We observed wide variation in the expression levels of the nonselected transgenes among independently-derived lines, but expression levels within lines derived from the same clone were similar. Consistent with previous reports, we observed no correlation between transgene copy number and the level or stability of protein expression. We show that the introduction of multiple agronomically valuable genes into the rice genome by cotransformation is a practical strategy for engineering elite rice varieties.
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  • 33
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    Plant molecular biology 39 (1999), S. 83-93 
    ISSN: 1573-5028
    Keywords: Arabidopsis ; Agrobacterium ; T-DNA ; CodA ; positive-negative selection ; recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have analysed the application of positive-negative selection for the selection of homologous recombination interactions between the chromosome and a T-DNA molecule after transformation of plant cells. Two different genomic loci in a cell suspension of Arabidopsis thaliana were chosen to study gene targeting events. One was the chalcone synthase (CHS) gene present as a single copy and the second an hemizygous chromosomally inserted T-DNA containing the hpt gene, conferring resistance to hygromycin, flanked by CHS sequences. The target lines were transformed with replacement-type T-DNA vectors which contained a positive selectable marker flanked by the regions of the CHS gene and a negative selectable marker to counter-select random insertions. As negative marker we used the Escherichia coli codA gene encoding cytosine deaminase, conferring upon the cells sensitivity to 5-flourocytosine (5-FC). Doubly selected transformants represent 1–4% of the primary transformed cells. Targeting events were not found at the chalcone synthase locus nor at the artificial hpt locus in a total of 4379 doubly selected calli, corresponding to at least 109 475 individual primary transformants. We show by PCR and Southern analysis that the 5-FC resistance in the majority of these cells is associated with substantial deletions of the T-DNA molecule from the right-border end.
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  • 34
    ISSN: 1573-5028
    Keywords: enhancer ; flavonoids ; particle bombardment ; pericarp ; promoter ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The maize P-rr gene conditions floral-specific flavonoid pigmentation, especially in the kernel pericarp and cob. We analyzed the P-rr promoter by transient expression assays, in which segments of the P-rr promoter were fused to the GUS reporter gene and introduced into maize cells by particle bombardment. A basal P-rr promoter fragment (−235 to +326) gave low, but significant, levels of GUS reporter gene expression. Interestingly, two widely spaced segments containing enhancer-like activity were found. When tested individually, both the proximal (−1252 to −236) and distal (−6110 to −4842) segments boosted expression of the basal P-rr promoter::GUS construct about five-fold. A 1.6 kb segment of the P-rr promoter (−1252 to +326) containing the proximal enhancer and the 5′-untranslated leader driving the GUS reporter gene showed preferential expression in BMS and embryogenic suspension cell cultures vs. endosperm-derived suspension cell cultures. These results demonstrate the application of transient assay techniques for the identification of regulatory elements responsible for floral-specific regulation of the complex P-rr gene promoter in maize.
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  • 35
    ISSN: 1573-5028
    Keywords: genetic engineering ; 4-hydroxybenzoic acid glucoside ; Lithospermum erythrorhizon ; menisdaurin ; shikonin ; ubiC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The biosynthetic pathway to 4-hydroxybenzoate (4HB), a precursor of the naphthoquinone pigment shikonin, was modified in Lithospermum erythrorhizon hairy root cultures by introduction of the bacterial gene ubiC. This gene of Escherichia coli encodes chorismate pyruvate-lyase (CPL), an enzyme that converts chorismate into 4HB and is not normally present in plants. The ubiC gene was fused to the sequence for a chloroplast transit peptide and placed under control of a constitutive plant promoter. This construct was introduced into L. erythrorhizon by Agrobacterium rhizogenes-mediated transformation. The resulting hairy root cultures showed high CPL activity. 4HB produced by the CPL reaction was utilized for shikonin biosynthesis, as shown by in vivo inhibition of the native pathway to 4HB with 2-aminoindan-2-phosphonic acid (AIP), an inhibitor of phenylalanine ammonia-lyase. A feeding experiment with [1,7-13C2]shikimate showed that in the absence of AIP the artificially introduced CPL reaction contributed ca. 20% of the overall 4HB biosynthesis in the transgenic cultures. ubiC transformation did not lead to a statistically significant increase of shikonin formation, but to a 5-fold increase of the accumulation of menisdaurin, a nitrile glucoside which is presumably related to aromatic amino acid metabolism.
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  • 36
    ISSN: 1573-5028
    Keywords: cellulase ; heterologous expression ; Hordeum vulgare L. ; particle bombardment ; thermotolerant endo-1.4-β-glucanase ; transgenic barley
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The malting quality of two barley cultivars, Kymppi and Golden Promise, was modified to better meet the requirements of the brewing process. The egl1 gene, coding for fungal thermotolerant endo-1,4-β-glucanase (EGI, cellulase), was transferred to the cultivars using particle bombardment, and transgenic plants were regenerated on bialaphos selection. Integration of the egl1 gene was confirmed by Southern blot hybridization. The transgenic seeds were screened for the expression of the heterologous EGI. Under the high-pI α-amylase promoter, the egl1 gene was expressed during germination. The heterologous enzyme was thermotolerant at 65 °C for 2 h, thus being suitable for mashing conditions. The amount of heterologous EGI produced by the seeds (ca. 0.025% of soluble seed protein), has been shown to be sufficient to reduce wort viscosity by decreasing the soluble β-glucan content. A decrease in the soluble β-glucan content in the wort improves the filtration rate of beer.
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  • 37
    ISSN: 1573-5060
    Keywords: gus expressing cells ; histological analysis ; japonica and indica rice ; particle bombardment ; primary callus ; regeneration capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The microprojectile bombardment procedure has allowed the stable transformation of indica and japonica rice varieties, although at different frequencies of transformation depending mainly on their regeneration capacity and on the specific parameters of the transformation protocol. A study of the process of regeneration to whole plants from primary calli derived from mature indica and japonica rice seeds, via embryogenesis, has shown that somatic embryos are produced by division and differentiation of the external cell layers of callus tissues. Adjusting the bombardment conditions to optimize gene delivery to those regenerable cells, we have evaluated the influence of parameters such as the target distance, particle penetration and the effect of osmotic treatment on the regeneration capacity of bombarded cells.
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  • 38
    ISSN: 1573-5028
    Keywords: Agrobacterium ; Ti plasmid ; oncogenes ; e gene ; 3′ gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Agrobacterium tumefaciens nopaline strain C58 transfers a large, 29 kb T-DNA into plant cells during infection. Part of this DNA (the `common DNA') is also found on the T-DNA of octopine strains, the remaining DNA is nopaline strain-specific. Up to now, only parts of the C58 T-DNA and related T37 T-DNA have been sequenced. We have sequenced the remainder of the nopaline-specific T-DNA (containing genes a to d) and acs to iaaM. Gene c codes for a new unknown T-DNA protein. Gene a is homologous to the agrocinopine synthase gene. Genes b, c′, d and e are part of a larger family: they are related to the T-DNA genes 5, rolB, lso and 3′. Genes 5, rolB and lso induce or modify plant growth and have been called T-DNA oncogenes. Our studies show that gene 3′ (located on the TR-DNA of octopine strains) is also oncogenic. Although the b–e T-DNA fragment from C58 and its individual genes lack growth-inducing activity, an a-acs deletion mutant was distinctly less virulent on Kalanchoe daigremontiana and showed reduced shoot formation on Kalanchoe tubiflora. Shoot formation could be restored by genes c and c′ in co-infection experiments. Contrary to an earlier report, a C58 e gene deletion mutant was fully virulent on all plants tested.
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  • 39
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    Photosynthesis research 60 (1999), S. 29-42 
    ISSN: 1573-5079
    Keywords: enzyme catalysis ; evolution ; genetic engineering ; photosynthesis ; protein assembly ; protein degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) has played a central role in our understanding of chloroplast biogenesis and photosynthesis. In particular, its catalysis of the rate-limiting step of CO2 fixation, and the mutual competition of CO2 and O2 at the active site, makes Rubisco a prime focus for genetically engineering an increase in photosynthetic productivity. Although it remains difficult to manipulate the chloroplast-encoded large subunit and nuclear-encoded small subunit of crop plants, much has been learned about the structure/function relationships of Rubisco by expressing prokaryotic genes in Escherichia coli or by exploiting classical genetics and chloroplast transformation of the green alga Chlamydomonas reinhardtii. However, the complexity of chloroplast Rubisco in land plants cannot be completely addressed with the existing model organisms. Two subunits encoded in different genetic compartments have coevolved in the formation of the Rubisco holoenzyme, but the function of the small subunit remains largely unknown. The subunits are posttranslationally modified, assembled via a complex process, and degraded in regulated ways. There is also a second chloroplast protein, Rubisco activase, that is responsible for removing inhibitory molecules from the large-subunit active site. Many of these complex interactions and processes display species specificity. This means that attempts to engineer or discover a better Rubisco may be futile if one cannot transfer the better enzyme to a compatible host. We must frame the questions that address this problem of chloroplast-Rubisco complexity. We must work harder to find the answers.
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  • 40
    ISSN: 1573-6776
    Keywords: β-glucuronidase ; Catharanthus roseus ; genetic transformation ; green fluorescent protein ; particle bombardment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In vitro propagation of Catharanthus roseus was achieved using nodal explants. Bud induction was best on medium containing 1.0 mg benzyl aminopurine l−1. Hardening of rooted shoots to soil was very successful with 98% survival. Genetically transformed C. roseus plantlets were obtained after bombardment of nodal explants, which were then micropropagated, with DNA coated particles with green fluorescent protein (GFP) or β-glucuronidase (GUS) reporter genes. Histological studies showed that the gene insertion method proved effective with many cells and different tissues displaying the reporter gene signals, showing that gene expressions were rather stable.
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  • 41
    ISSN: 1573-8469
    Keywords: Agrobacterium ; crown gall ; systemic infection ; rose ; endophyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Agrobacterium tumefaciens was isolated from stem tumors of several rose cultivars showing that the bacterium is the causal agent of aerial galls in rose plants. No differences were observed in the characteristics of the Agrobacterium isolates from crown or aerial galls. Stem inoculation of ten rose cultivars showed that all of them were susceptible to A. tumefaciens but differences in the size of the resulting tumors were observed. The movement of A. tumefaciens in rose plants was demonstrated using two wild type strains and two antibiotic resistant mutants. Three months after inoculation, the inoculated strains were recovered in the roots, crown and below and above the inoculation site but low numbers of pathogenic Agrobacterium cells were isolated. New tumors appeared in 5% of the noninoculated wounds. A. tumefaciens was isolated from the stem at different distances from the tumor in naturally infected plants. In symptomless commercial plants, the isolation from the roots, crown and at different stem levels demonstrated the existence of systemic and latent infections in rose. Direct isolation using a nonselective and selective media with or without a previous enrichment step were efficient methods for isolating tumorigenic Agrobacterium from the different parts of rose plants.
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  • 42
    ISSN: 1573-9368
    Keywords: Antirrhinum ; Arabidopsis ; green fluorescent protein (GFP) ; in vitro ; microspores ; particle bombardment ; tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The transient expression of three mutant forms of green fluorescent protein (GFP) genes, GFP4, GFP5ER, and GFP4S65C, under several constitutive and pollen‐specific promoters throughout pollen development in Nicotianatabacum, thaliana and Antirrhinummajus is described. Immature pollen of tobacco, Arabidopsis and snapdragon, isolated at different developmental stages, were bombarded with plasmids containing the GFP and cultured in vitro for several days until maturity. The expression of GFP was monitored every day during in vitro maturation, germination and pollination, as well as after in situ pollination. The expression pattern of each construct was compared in parallel experiments to that of ß‐glucuronidase (GUS) constructs expressed by the same promoters. The results show that the expression level of all three GFP mutant forms was dependent on the strength of the promoter used. The strongest promoter was the DC3 promoter, and no notable differences in the intensity and brightness of all three versions of GFP were observed. GFP‐expressing pollen from tobacco and snapdragon developed in vitro for several days until maturity and germinated in vitro as well as on the surface of stigmata, strongly suggesting that all three GFPs are not toxic for the development of functional pollen. Furthermore, stably transformed tobacco plants expressing GFP under the control of the strong pollen‐expressed DC3 and LAT52 promoters were not impaired in reproductive function, confirming that GFP can be used as a non‐destructive marker for plant reproductive biology and development.
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  • 43
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    Antonie van Leeuwenhoek 73 (1998), S. 117-126 
    ISSN: 1572-9699
    Keywords: riboplasmids ; encapsidation ; pseudovirions ; selfish plasmids ; replicons ; ribozyme ; Agrobacterium ; Rhizobium ; grapevines ; L-tartrate ; lignin ; methoxyphenols ; satellite viruses ; opines ; crown gall ; T-DNA ; origin of replication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Studies on the origin and evolution of plasmids may provide valuable insights on the promiscuous nature of DNA. The first examples of the selfish nature of nucleic acids are exemplified by primordial oligoribonucleotides which evolved into primitive replicons. The propagation of these molecules were likely patterned after the current viral RNA ribozymes, which have been recently shown to possess RNA synthesizing and template mediated polymerizing capabilities in the absence of proteins. The parasitic nature of nucleic acids is depicted by satellite nucleic acid molecules associated with viruses. The satellites of adenovirus and tobacco ringspot virus serve as established examples: they contain no open reading frames. Comparative analysis of the replication origins of virions and plasmids show them to be conserved, originating from the simplest autocatalytic replicon to highly complex and evolved plasmids, replicating by a rolling circle mechanism. The eventual association of proteins with nucleic acids provided added efficiency and protective advantages for molecular perpetuation. The promiscuous and selfish nature of plasmids is demonstrated by their ability to genetically engineer their host so that the host cell is best able to cope and survive in hostile environments. Survival of the host ensures survival of the plasmid. Sequestering of genes by plasmids occurs when the environmental conditions negatively affect the host. The sequestering mechanism is fundamental and forms the outreach mechanisms to generate and propagate macromolecules of increasing size when necessary for survival. The level of sophistication of plasmids increases with the addition of new genes such as those that allow the host to occupy a specific environment normally inhospitable to the host cell. The vast range of plasmid types which have obtained genes interchangeably reflect the levels of sophistication achieved by these macromolecules. The Ti plasmid in Agrobacterium tumefaciens and the pSym and accessory plasmids in Rhizobium illustrate the level of complexity attained by replicons.
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  • 44
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    Plant cell reports 18 (1998), S. 308-311 
    ISSN: 1432-203X
    Keywords: Key words Campanulaceae ; Lobelia erinus ; Transformation ; Agrobacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A transformation/regeneration system was developed for the common garden Lobelia (Lobelia erinus). Using an Agrobacterium-based protocol, over 40 transformants have been generated with four different binary vectors. The explant source was hypocotyl-root sections from axenically grown seedlings. Stable transformation was demonstrated by Southern hybridization analysis, β-glucuronidase staining, and transmission of the T-DNA to progeny. This extends the ever-widening range of transformable plant species to the Campanulaceae and will allow molecular studies of development and physiology in this easily cultured and popular garden plant.
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  • 45
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    Plant cell reports 18 (1998), S. 180-186 
    ISSN: 1432-203X
    Keywords: Key words Soybean ; SAAT (sonication assisted Agrobacterium-mediated transformation) ; Agrobacterium ; Transformation ; KYRT1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cotyledonary node transformation efficiency was evaluated using a sonication assisted Agrobacterium-mediated transformation (SAAT) protocol, three dissimilar A. tumefaciens strains, and explants derived from 28 diverse cultivars and/or genotypes of soybean [Glycine max (L.) Merr.]. The explants were evaluated at 10 and 45 days after co-cultivation for transformation with a binary vector containing both a GUS-intron gene and an NPTII selectable marker. The best overall strain of A. tumefaciens was determined to be KYRT1 based on stable GUS transformation of soybean cotyledonary node explants measured at the terminal 45 day evaluation point. SAAT did not increase stable transformation at 45 days post co-cultivation. SAAT was determined to significantly decrease shoot proliferation of some genotypes, but it is unclear what effect this may have on the recovery of transformed shoots. Significant differences were also detected between genotypes for transformation and shoot proliferation frequency.
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  • 46
    ISSN: 1432-203X
    Keywords: Key words Peppermint ; Transformation ; Agrobacterium ; GUS ; Transgenic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The first transgenic peppermint (Mentha×piperita L. cultivar Black Mitcham) plants have been obtained by Agrobacterium-mediated transformation by cocultivation with morphogenically responsive leaf explants. Basal leaf explants with petioles, from leaves closest to the apex of in-vitro-culture-maintained shoots (5 cm), exhibited optimal shoot organogenetic responsiveness on medium supplemented with thidiazuron (8.4 µm). Shoot formation occurred at sites of excision on the leaf blade and petiole either directly from cells of the explant or via a primary callus. Analyses of transient GUS activity data indicated that DNA delivery by microprojectile bombardment was more effective than Agrobacterium infection. However, no transgenic plants were obtained from over 22,000 leaf explants after particle bombardment. Cocultivation of leaf explants with Agrobacterium strain EHA 105 and kanamycin selection produced transgenic plants. Greater transient and stable -glucuronidase (GUS) activities were detected in explants or propagules transformed with the construct where gusA was driven by the pBISN1 promoter rather than a CaMV 35S promoter. Eight plants were subsequently regenerated and verified as transgenic based on detection of the nptII transgene by PCR and Southern blot analyses. The Southern analyses indicated that the plants were derived from eight unique transformation events. All transgenic plants appeared morphologically normal. Analyses of GUS activities in leaves sampled from different portions of these transgenic plants, 10 months after transfer to the greenhouse, indicated that six out of the eight original regenerants were uniformly transformed, i.e., did not exhibit chimeric sectors.
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  • 47
    ISSN: 1432-203X
    Keywords: Key words Genetic transformation ; Agrobacterium ; Eucalyptus ; Regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An efficient system for Agrobacterium-mediated transformation of Eucalyptus camaldulensis and production of transgenic plants was developed. Transformation was accomplished by cocultivation of hypocotyl segments with Agrobacterium tumefaciens containing a binary Ti-plasmid vector harboring chimeric neomycin phosphotransferase and β-glucuronidase (GUS) genes. A modified Gamborg's B5 medium used in this study was effective for both callus induction and regeneration of transgenic shoots. This medium could also effectively maintain the organogenic capability of callus for more than a year. Culturing transgenic shoots in Murashige and Skoog medium supplemented with 0.1 mg ⋅ l–1 benzylaminopurine prior to root induction in rooting medium markedly increased the rootability of shoots that were recalcitrant to rooting. Histochemical assay revealed the expression of the GUS gene in leaf, stem, and root tissues of transgenic plants. Insertion of the GUS gene in the nuclear genome of transgenic plants was verified by genomic Southern hybridization analysis, further confirming the integration and expression of T-DNA in these plants.
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  • 48
    ISSN: 1432-203X
    Keywords: Key wordsBetula pendula ; Transformation ; Agrobacterium ; Gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Early flowering together with small size would be useful for various biotechnical or genetic studies on trees. We report here the selection and micropropagation of early flowering birch (Betula pendula) clones (BPM1–12) obtained from seeds of birches bred elsewhere for early flowering. Under conditions that accelerate flowering (a high CO2 level, strong and continuous illumination), the first male inflorescences emerged in 3–5 months, the trees then being 20–80 cm high. Transgenic lines (CaMV 35S-GUS INT) were produced through Agrobacterium-mediated gene transfer from BPM2, BPM5 and JR1/4 (a normally flowering birch). β-Glucuronidase (GUS) activities in the different lines, assayed 1–1.5 years after transformation, varied greatly. During further in vitro culture for 10 months, the activities decreased to 0.3–7% of the original values. GUS activities were detected in all organs studied, including the developing male inflorescences; the highest activity was in the roots.
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  • 49
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    Plant cell reports 17 (1998), S. 822-826 
    ISSN: 1432-203X
    Keywords: Key words Rosaceae ; β-Glucuronidase ; Regeneration ; Agrobacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genetic transformation of arctic bramble (Rubus arcticus L.) was achieved utilizing a Ti-plasmid vector system of Agrobacterium tumefaciens. Internodal stem segments were inoculated with Agrobacterium strain EHA101 carrying a T-DNA with the CaMV 35 S promoter-gus-int marker gene from which β-glucuronidase (GUS) is expressed only in plants. Regenerants were produced on Murashige and Skoog medium. Growth of Agrobacterium was inhibited with cefotaxime. Kanamycin was used as the selective agent for the transformants. Regenerants were assayed by histochemical GUS staining, and by Southern analysis using a gus-int probe. Transgenic arctic bramble plants containing gus-int and expressing GUS were recovered. Expression has been stable for 3 years in micropropagation.
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  • 50
    ISSN: 1432-203X
    Keywords: Key wordsHevea brasiliensis ; Agrobacterium ; CaMV 35S ; β-Glucuronidase ; Latex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hevea brasiliensis anther calli were genetically transformed using Agrobacterium GV2260 (p35SGUSINT) that harboured the β-glucuronidase (gus) and neomycin phosphotransferase (nptII) genes. β-Glucuronidase protein (GUS) was expressed in the leaves of kanamycin-resistant plants that were regnerated, and the presence of the gene was confirmed by Southern analysis. GUS was also observed to be expressed in the latex and more importantly in the serum fraction. Transverse sections of the leaf petiole from a transformed plant revealed GUS expression to be especially enhanced in the phloem and laticifers. GUS expression was subsequently detected in every one of 194 plants representing three successive vegetative cycles propagated from the original transformant. Transgenic Hevea could thus facilitate the continual production of foreign proteins expressed in the latex.
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  • 51
    ISSN: 1573-9368
    Keywords: sweet orange ; Citrus ; woody ; transformation ; Agrobacterium ; mature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regeneration and transformation systems from mature plant material of woody fruit species have to be achieved as a necessary requirement for the introduction of useful genes into specific cultivars and the rapid evaluation of resulting horticultural traits. We report here, for the first time, a procedure for genetic transformation and regeneration of mature tissues of woody plants that overcomes the long juvenile periods and high heterozygosity that are characteristic of most of these species. An improved regeneration frequency from mature explants was obtained by invigoration of the plant material through grafting of mature buds on juvenile seedlings. Co-cultivation of the explants in feederplates after inoculation with Agrobacterium tumefaciens resulted in enhanced transformation frequencies. Furthermore, in vitro shoot-tip grafting of the regenerated mature shoots on seedling rootstocks provided a rapid and efficient system for plant production. Citrus is the most extensivel y grown fruit crop worldwide and sweet orange (Citrus sinensis L. Osbeck) accounts for approximately 70% of the Citrus total production. Mature transgenic sweet orange plants have been obtained, which flowered and bore fruit in 14 months
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  • 52
    ISSN: 1573-9368
    Keywords: Saccharum ; Agrobacterium ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This is the first successful report of the recovery of morphologically normal transgenic sugarcane plants from co-cultivation of calluses with Agrobacterium tumefaciens. Transformation frequencies (total of transgenic plants/number of cell clusters) were between 9.4 × 10−3 and 1.15 × 10−2. In our experiments, both LBA4404 (pTOK233) and EHA101 (pMTCA3IG), carrying a super-binary vector or supervirulent strain, respectively, were successful for sugarcane transformation. We found that three main factors: (1) the use of young regenerable calluses as target explants; (2) induction and/or improvement of the A. tumefaciens virulence system with sugarcane cell cultures and (3) pre-induction of organogenesis or somatic-embryogenesis-like sexual embryos, seem to be crucial in order to increase the cells competence for T-DNA transfer process. Patterns generated by Southern hybridization confirmed that T-DNAs were randomly integrated into sugarcane genome without th e persistence of A. tumefaciens in the transgenic plants
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  • 53
    ISSN: 1573-9368
    Keywords: Oryza sativa ; particle bombardment ; transformation ; transgenic rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We developed a practical and efficient gene transfer system for indica rice utilizing mature-seed derived explants and a simple bombardment device which uses compressed helium for accelerating DNA-coated metal particles. Unlike instruments which have been described in the literature previously, this new bombardment device, which is an improvement of the particle inflow concept, does not require vacuum. This attribute simplifies the transformation procedure significantly and it makes rice transformation technology accessible to laboratories which may not have the resources to invest in more expensive particle bombardment instruments. We determined experimentally that we could recover transgenic rice plants utilizing three different particle bombardment instruments at comparable frequencies.
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  • 54
    ISSN: 1573-9368
    Keywords: particle bombardment ; transgene expression ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A population of R0 transgenic wheat plants, generated by particle bombardment, was analyzed to define molecular, genetic and phenotypic properties resulting from transformation with a cointegrate vector, or cotransformation with two separate plasmids. By evaluating the progeny of 70 independently-derived transgenic plants, we also identified rare events such as chimerism and transgene elimination, which provide valuable information concerning the development of transgenic cereal plants following bombardment experiments. The frequency of chimerism in our transgenic wheat plants was very low. Furthermore, while transgene elimination did occur, this was also a very rare event. We determined the copy numbers of integrated transgenes and the levels of transgene expression. Comparisons to transgenic rice plants generated in the same manner demonstrated some similarities, but also important differences in transgene behavior. Whereas in rice there is no evidence for any direct relationship between transgene copy number and transgene expression or stability, multicopy populations in wheat demonstrated a bias towards higher levels of expression for the two genes and the maize ubiquitin promoter evaluated in the present study.
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  • 55
    ISSN: 1572-9788
    Keywords: transgenic rice ; particle bombardment ; cell electroporation ; RAPD ; AFLP ; AFRP ; RAMP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In the present work we utilised some of the most discriminative molecular tools, such as RAPD, AFLP, AFRP and RAMP, to analyse the genome of independently derived transgenic plants from three elite Italian cultivars (cv. Lido, Carnaroli and Thaibonnet) and found that two methods for direct gene transfer, namely particle bombardment and intact cell electroporation (the latter being a procedure set up in this work), result in transgenic rice (Oryza sativa L.) plants that exhibit negligible genomic changes. This is in contrast with recently published results showing relevant changes in the DNA of transgenic rice plants generated through protoplasts electroporation and of transgenic poplar plants engineered through Agrobacterium tumefaciens infection. Implications of these findings are discussed in the context of selecting appropriate gene transfer methodologies to produce transgenic plants expressing genes of interest while retaining their genomic integrity and, thus, their superior agronomic and/or industrial traits.
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  • 56
    ISSN: 1572-9788
    Keywords: Bacillus thuringiensis (Bt) ; cry2A ; particle bombardment ; rice leaf folder ; transgenic rice ; yellow stem borer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Transgenic rice indica varieties Basmati 370 and M 7 expressing the novel cry2A (Bt) insecticidal gene were generated by particle bombardment. Molecular and biochemical analyses in R0 and R1 populations confirmed stable integration and expression of this novel Bt transgene. We estimated that the gene product was expressed up to 5% of total leaf protein. Insect feeding bioassays demonstrated that the Cry2A protein was effective against the yellow stem borer and the rice leaf folder, two major rice pests in the Indian Subcontinent. This is the first report of the control of major rice pests using this specific Bt gene. The cry2A gene can now be used in combination with other insecticidal genes for pyramiding resistance against insect pests. This will delay, or perhaps in combination with integrated pest management practices, prevent evolution of insect populations resistant to single insecticidal genes.
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  • 57
    ISSN: 1572-9788
    Keywords: chitinase ; Diplocarpon rosae ; disease resistance ; genetic engineering ; Rosa hybrida L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Blackspot, caused by the Ascomycete fungus Diplocarpon rosae, is the most widespread and pernicious disease of cultivated roses. While some species of rose possess resistance to D. rosae, none of the modern-day rose cultivars are fully resistant to the pathogen. In the current study, Biolistic gene delivery was used to introduce a rice gene, encoding a basic (Class I), chitinase into embryogenic callus of the blackspot-susceptible rose (Rosa hybrida L.) cv. Glad Tidings. The plasmid used for transformation carried the neomycin phosphotransferase (nptII) gene facilitating the selection and regeneration of transgenic plants on medium containing 250 mg/l kanamycin. Southern analysis confirmed integration of 2–6 copies of the chitinase gene into the rose genome; gene expression was confirmed by enzyme assay. Bioassays demonstrated that expression of the chitinase transgene reduced the severity of blackspot development by 13–43%. This degree of resistance to the pathogen correlated with the level of chitinase expression in the transgenic rose plants. The introduction of disease defence genes into rose provides a method of producing blackspot-resistant rose cultivars sought by breeders and growers.
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  • 58
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    Molecular breeding 4 (1998), S. 531-541 
    ISSN: 1572-9788
    Keywords: Agrobacterium ; Brassica oleracea ; cauliflower ; regeneration ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We have developed an efficient and simpler method for genetic transformation and regeneration of cauliflower, Brassica oleracea var. botrytis plants. Explants from 4-day old seedlings were inoculated and cocultivated with Agrobacterium tumefaciens strain LBA4404 harbouring a binary vector with the neomycin phosphotransferase-II gene under the regulatory control of nopaline synthase promoter and terminator sequences, permitting transformed shoots to be selected on kanamycin containing medium. After three months rooted transformed plantlets were successfully transferred and grown under glasshouse conditions. Higher numbers of transformed plants were obtained from cotyledon than hypocotyl explants, presumably indicating cotyledons of cauliflower are more amenable to genetic transformation. Integration and expression of the introduced transgene were analysed by DNA gel blot and PCR analysis and NPT-II expression assay. Factors influencing transformation efficiency include explant age, concentration of bacterium used for infection, duration of infection and cocultivation with Agrobacterium. Transgenic plants of three commercial genotypes of cauliflower were produced using this method. We also show that introduction of antisense Bcp1 (pollen-specific gene) linked to a pollen-specific promoter (Lat52) resulted in the expected sterility of 50% pollen carrying this transgenic construct.
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  • 59
    ISSN: 1572-9788
    Keywords: BGMV ; common bean ; particle bombardment ; plant transformation ; virus resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The genes Rep-TrAP-REn and BC1 from the Brazilian isolate bean golden mosaic geminivirus (BGMV-BR) were cloned in antisense orientation under the transcriptional control of the CaMV 35S promoter. This construct was used to transform common bean (Phaseolus vulgaris L.) using the biolistic method. Transgenic plants from the R3 and R4 generations were challenged by inoculation with a BGMV-BR viruliferous whitefly population. Of the four transgenic lines tested, two had both delayed and attenuated viral symptoms. Un-transformed plants or plants transformed with a construct containing only the gus-neo gene developed typical BGMV-BR symptoms 10–15 days after inoculation.
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  • 60
    ISSN: 1573-5028
    Keywords: Agrobacterium ; apple ; GFP ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To investigate early events of Agrobacterium-mediated transformation of apple cultivars, a synthetic green fluorescent protein gene (SGFP) was used as a highly sensitive, vital reporter gene. Leaf explants from four apple cultivars (‘Delicious’, ‘Golden Delicious’, ‘Royal Gala’ and ‘Greensleeves’) were infected with Agrobacterium EHA101 harboring plasmid pDM96.0501. Fluorescence microscopy indicated that SGFP expression was first detected 48 h after infection and quantitative analysis revealed a high T-DNA transfer rate. Plant cells with stably incorporated T-DNA exhibited cell division and developed transgenic calli, followed by formation of transgenic shoots at low frequencies. The detection of SGFP expression with an epifluorescence stereomicroscope confirmed the effectiveness of SGFP as a reporter gene for detection of very early transformation events and for screening of putative transformants. The efficiency of the transformation and regeneration process decreased ca. 10000-fold from Agrobacterium infection to transgenic shoot regeneration, suggesting that factors other than Agrobacterium interaction and T-DNA transfer are rate-limiting steps in Agrobacterium-mediated transformation of apple.
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  • 61
    ISSN: 1573-5060
    Keywords: Agrobacterium ; barley ; C1/Lc ; GFP ; GUS ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Transfer of T-DNA from Agrobacterium tumefaciens and A. rhizogenes to cells of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) is demonstrated following the inoculation of immature embryos and immature embryo-derived callus. Agrobacterium T-DNA vectors containing the C1/Lc anthocyanin-biosynthesis regulatory genes, the gusA gene or a synthetic green fluorescent protein gene (sgfp-S65T) were constructed from original binary vectors. The visual T-DNA markers were used as cell-autonomous reporters of early Agrobacterium-mediated transformation events in the wheat and barley cells. This localization of the transformed cells revealed a non-random distribution throughout each embryo and callus piece.
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  • 62
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    Plant molecular biology 38 (1998), S. 1011-1019 
    ISSN: 1573-5028
    Keywords: choline oxidase ; genetic engineering ; glycinebetaine ; low-temperature tolerance ; salt tolerance ; transgenic rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genetically engineered rice (Oryza sativa L.) with the ability to synthesize glycinebetaine was established by introducing the codA gene for choline oxidase from the soil bacterium Arthrobacter globiformis. Levels of glycinebetaine were as high as 1 and 5 μmol per gram fresh weight of leaves in two types of transgenic plant in which choline oxidase was targeted to the chloroplasts (ChlCOD plants) and to the cytosol (CytCOD plants), respectively. Although treatment with 0.15 m NaCl inhibited the growth of both wild-type and transgenic plants, the transgenic plants began to grow again at the normal rate after a significantly less time than the wild-type plants after elimination of the salt stress. Inactivation of photosynthesis, used as a measure of cellular damage, indicated that ChlCOD plants were more tolerant than CytCOD plants to photoinhibition under salt stress and low-temperature stress. These results indicated that the subcellular compartmentalization of the biosynthesis of glycinebetaine was a critical element in the efficient enhancement of tolerance to stress in the engineered plants.
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  • 63
    ISSN: 1573-5028
    Keywords: Agrobacterium ; Arabidopsis ; Cre/lox ; recombination ; site-specific integration ; T-DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Cre/lox system was used to obtain targeted integration of an Agrobacterium T-DNA at a lox site in the genome of Arabidopsis thaliana. Site-specific recombinants, and not random events, were preferentially selected by activation of a silent lox-neomycin phosphotransferase (nptII) target gene. To analyse the effectiveness of Agrobacterium-mediated transfer we used T-DNA vectors harbouring a single lox sequence (this vector had to circularize at the T-DNA left- and right-border sequences prior to site-specific integration) or two lox sequences (this vector allowed circularization at the lox sequences within the T-DNA either prior to or after random integration, followed by targeting of the circularized vector), respectively. Furthermore, to control the reversibility of the integration reaction, Cre recombinase was provided transiently by using a cotransformation approach. One precise stable integrant was found amongst the recombinant calli obtained after transformation with a double-lox T-DNA vector. The results indicate that Agrobacterium-mediated transformation can be used as a tool to obtain site-specific integration.
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  • 64
    ISSN: 1573-5060
    Keywords: particle bombardment ; promoter ; tissue-specificity sucrose synthase ; transient expression ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The reporter gene encoding β-glucuronidase (GUS) driven by either of the two maize sucrose synthase gene (Sh1 and Sus 1) promoters was introduced and expressed in various maize tissues via particle bombardment. Transient gene expression was examined by histochemical assays. It was found that the two SS promoters directed differential GUS expression. In the developing kernel, the Sh1 promoter was active only in the upper and central parts of the endosperm. In contrast, strong GUS activity controlled by the Sus1 promoter was detected in various types of cells, including the aleurone cells, the subaleurone endosperm cells, the scutellar cells of the embryo and the pericarp cells. Both promoters showed similar expression patterns in vegetative tissues.
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  • 65
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    Biotechnology and Bioengineering 58 (1998), S. 162-169 
    ISSN: 0006-3592
    Keywords: bioinformatics ; metabolic engineering ; genetic engineering ; mathematical analysis ; stoichiometry ; enzyme kinetics ; modal analysis ; genetic circuits ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ten microbial genomes have been fully sequenced to date, and the sequencing of many more genomes is expected to be completed before the end of the century. The assignment of function to open reading frames (ORFs) is progressing, and for some genomes over 70% of functional assignments have been made. The majority of the assigned ORFs relate to metabolic functions. Thus, the complete genetic and biochemical functions of a number of microbial cells may be soon available. From a metabolic engineering standpoint, these developments open a new realm of possibilities. Metabolic analysis and engineering strategies can now be built on a sound genomic basis. An important question that now arises; how should these tasks be approached? Flux-balance analysis (FBA) has the potential to play an important role. It is based on the fundamental principle of mass conservation. It requires only the stoichiometric matrix, the metabolic demands, and some strain specific parameters. Importantly, no enzymatic kinetic data is required. In this article, we show how the genomically defined microbial metabolic genotypes can be analyzed by FBA. Fundamental concepts of metabolic genotype, metabolic phenotype, metabolic redundancy and robustness are defined and examples of their use given. We discuss the advantage of this approach, and how FBA is expected to find uses in the near future. FBA is likely to become an important analysis tool for genomically based approaches to metabolic engineering, strain design, and development. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:162-169, 1998.
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  • 66
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    Proteins: Structure, Function, and Genetics 30 (1998), S. 155-167 
    ISSN: 0887-3585
    Keywords: X-ray diffraction ; protein folding ; genetic engineering ; circular permutation ; 1,3-1,4-β-glucanase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The 1,3-1,4-β-glucanases from Bacillus macerans and Bacillus licheniformis, as well as related hybrid enzymes, are stable proteins comprised of one compact jellyroll domain. Their structures are studied in an effort to reveal the degree of redundancy to which the three-dimensional structure of protein domains is encoded by the amino acid sequence. For the hybrid 1,3-1,4-β-glucanase H(A16-M), it could be shown recently that a circular permutation of the sequence giving rise to the variant cpA16M-59 is compatible with wildtype-like enzymatic activity and tertiary structure (Hahn et al., Proc. Natl. Acad. Sci. USA 91:10417-10421, 1994). Since the circular permutation yielding cpA16M-59 mimicks that found in the homologous enzyme from Fibrobacter succinogenes, the question arose whether de novo circular permutations, not guided by molecular evolution of the 1,3-1,4-β-glucanases, could also produce proteins with native-like fold. The circularly permuted variants cpA16M-84, cpA16M-127, and cpA16M-154 were generated by PCR mutagenesis of the gene encoding H(A16-M), synthesized in Escherichia coli and shown to be active in β-glucan hydrolysis. CpA16M-84 and cpA16M-127 were crystallized in space groups P21 and P1, respectively, and their crystal structures were determined at 1.80 and 2.07 Å resolution. In both proteins the main parts of the β-sheet structure remain unaffected by the circular permutation as is evident from a root-mean-square deviation of main chain atoms from the reference structure within the experimental error. The only major structural perturbation occurs near the novel chain termini in a surface loop of cpA16M-84, which becomes destabilized and rearranged. The results of this study are interpreted to show that: (1) several circular permutations in the compact jellyroll domain of the 1,3-1,4-β-glucanases are tolerated without radical change of enzymatic activity or tertiary structure, (2) the three-dimensional structures of simple domains are encoded by the amino acid sequence with sufficient redundancy to tolerate a change in the sequential order of secondary structure elements along the sequence, and (3) the native N-terminal region is not needed to guide the folding polypeptide chain toward its native conformation. Proteins 30:155-167, 1998. © 1998 Wiley-Liss, Inc.
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  • 67
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    Pharmaceutical research 15 (1998), S. 813-815 
    ISSN: 1573-904X
    Keywords: genetic engineering ; polymers ; drug delivery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 68
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    World journal of microbiology and biotechnology 14 (1998), S. 321-330 
    ISSN: 1573-0972
    Keywords: Conifer transformation ; forestry ; genetic engineering ; plantation forestry ; tree improvement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Genetic improvement in plantation forestry relies significantly on conventional breeding techniques which have been used extensively to improve various characteristics in forest trees such as growth and form, volume yield, resistance to pathogens and quality of the end product. This review concentrates on molecular techniques which have been used successfully in agriculture and which have more recently become available to improve further characteristics of forest trees and introduce new traits which are currently not available in the breeding population.
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  • 69
    ISSN: 1573-9368
    Keywords: rice transformation ; GNA ; particle bombardment ; immunolocalisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transgenic rice (Oryza sativa L.) plants generated through particle bombardment expressed high levels of an insecticidal protein (the snowdrop lectin, GNA) directed against sap-sucking insects. Engineered plants expressed GNA either constitutively or in a tissue specific manner, depending on the nature of the promoter used to drive expression of the gene. We used specific antibodies raised against GNA to localize its expression in phloem tissue in plants engineered with the rice sucrose synthase promoter driving GNA expression. We report here molecular, biochemical and immunological analyses for fifteen independently-derived transformants out of more than 200 plants we generated.
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  • 70
    ISSN: 1573-9368
    Keywords: bioreactor ; gene farming ; genetic engineering ; mammary gland ; milk composition ; recombinant protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract One transgenic rabbit line was generated carrying a fusion gene consisting of the cDNA for human IGF-1 fused to a mammary gland specific expression cassette derived from bovine alpha-S1-casein sequences. Transgene expression was shown to be strictly tissue and lactation period specific. The transgenic rabbit line was bred for six generations. All transgenic animals showed stable production of biologically active IGF-1 over the generations and no apparent effect on the physiological or reproductive performance was observed. The absence of adverse effects on homozygous transgenic rabbits suggested the absence of insertional mutagenesis. Eight hemizygous transgenic offspring analysed produced on average 363 ± 12μg/ml (ranging from 223 ± 61 to 484 ± 39 μg/ml) mature human IGF-1 in their milk, whereas three homozygous animals produced on average 543 ± 41 μg/ml (ranging from 360 ± 15 to 678 ± 80 μg/ml). Homozygous huIGF-1 females clearly showed a significantly increased production performance of the recombinant protein.
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  • 71
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    New York : Wiley-Blackwell
    Biopolymers 45 (1998), S. 269-279 
    ISSN: 0006-3525
    Keywords: spider dragline silk ; genetic engineering ; glycine-rich sequence ; β-sheet structure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We described genetically engineered syntheses of tandem repetitive polypeptides consisting of glycine-rich sequence, GlyLeuGlyGlyGlnGlyGlyGlyAlaGlyGlnGlyGlyTyrGly, designated SCAP(1), in spidroin I of spider dragline silk from Nephila clavipes and the secondary conformational analyses in the solid state by Fourier transform ir measurements. The polypeptides composed of 4, 5, 6, 7, 11, 12, or 13 repeats of SCAP(1) were expressed in Escherichia coli, purified by nickel chelate affinity chromatography, and then cleaved with cyanogen bromide to release N- and C-terminal extensions. Typical yields were from 1.2 to 5.2 mg of lyophilized uncleaved polypeptides per liter of fermentation medium at an absorbance of 2.0 at 600 nm, and the production levels increased with decreasing the molecular weight of the expressed polypeptides. The lyophilized powder of cleaved SCAP(13) adopted the random coil, whereas the cast film from formic acid formed the β-sheet structure. The conformational results might indicate that the glycine-rich sequence formed β-sheet structure in spidroin I. Cleaved SCAP(13) started to decompose under nitrogen at ca. 230°C, which was in agreement with the decomposition temperature of the spider dragline silk from N. clavipes. © 1998 John Wiley & Sons, Inc. Biopoly 45: 269-279, 1998
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  • 72
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    Biotechnology and Bioengineering 57 (1998), S. 477-483 
    ISSN: 0006-3592
    Keywords: Vitreoscilla hemoglobin ; bacterial hemoglobin ; Serratia marcescens ; genetic engineering ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The bacterial hemoglobin from Vitreoscilla has been shown to increase growth yield and yield of genetically engineered product in Escherichia coli. To test the generality of this phenomenon, the approximately 560-bp bacterial (Vitreoscilla) hemoglobin gene (vgb) (including the native promoter), cloned into the vector pUC8 in two constructs containing about 1650 and 850 bp, respectively, of Vitreoscilla DNA downstream of vgb, was transformed into Serratia marcescens. After several transfers of the transformants on selective media, both plasmids became stable in this host and the resulting strains produced hemoglobin. Both transformants were compared, regarding growth in liquid Luria-Bertani (LB) medium, with untransformed S. marcescens and S. marcescens transformed with pUC8. The vgb-bearing strains had about 5 times lower maximum viable cell numbers than the strains without hemoglobin, but the former also had late log or early stationary phase cells that were 5-10 times larger than those of the latter. Further, on a dry cell mass basis the presence of vgb inhibited cell growth in liquid media. In contrast, growth of the vgb-bearing strains on LB plates based on cell mass (determined from colony size) was markedly enhanced compared with that of the pUC8 transformant. Respiration of the vgb-bearing strains was lower than that of the strains without vgb on a cell mass basis. These results show that the presence of vgb can have idiosyncratic effects and is not always an aid to cell growth so that its use for genetic engineering must be tested on a case by case basis. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 477-483, 1998.
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  • 73
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    Journal of Physical Organic Chemistry 11 (1998), S. 536-539 
    ISSN: 0894-3230
    Keywords: enzyme design ; enzyme mechanism ; genetic engineering ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Aspartate aminotransferase (AATase) and aminocyclopropane carboxylate synthase (ACC synthase) are pyridoxal phosphate (PLP)-dependent enzymes whose common junction of mechanistic divergence is after the formation of a Cα carbanion from the amino acid substrate bound to PLP as a Schiff base (aldimine). AATase catalyzes the reversible interconversion of α-amino acids and α-keto acids, while ACC synthase effects the irreversible decomposition of S-adenosylmethionine (SAM) to 1-aminocyclopropane-1-carboxylate (ACC) and 5′-methylthioadenosine (MTA). ACC is subsequently converted to ethylene, the plant ripening and senescence hormone, by ACC oxidase, the next enzyme in the pathway. AATase and ACC synthase exhibit many similar phenomenological characteristics that result from different detailed mechanistic origins. The kcat/KM versus pH profiles for both enzymes are similar (AATase, acidic pKa = 6.9, basic pKa = 9.6; ACC synthase, acidic pKa = 7.5, basic pKa = 8.9); however the acidic pKa of AATase reflects the ionization of an enzyme proton from the internal Schiff base, and the basic one is that of the α-amino group of the substrate, while the opposite situation obtains for ACC synthase, i.e. the apparent pKa of 7.4 is due to the α-amino group of SAM, whereas that of 9 reflects the Schiff base pKa. The mechanistic imperative underlying this reversal is dictated by the reaction mechanism and the low pKa of the α-amino group of SAM. The low pKa of SAM requires that the enzyme pKa be moved upward in order to have sufficient quantities of the reacting species at neutral pH. It is shown by viscosity variation experiments with wild-type and active site mutant controls of both enzymes that the reaction of SAM with ACC synthase is 100% diffusion controlled (kcat/KM = 1.2 × 106 l mol-1 s-1) while the corresponding reaction for the combination of L-aspartate with AATase is insensitive to viscosity, and is therefore chemically not diffusion limited. Tyr225 (AATase) or Tyr233 (ACC synthase) forms a hydrogen bond with the PLP in both enzymes, but that formed with the former enzyme is stronger and accounts for the lower pKa of the Schiff base. © 1998 John Wiley & Sons, Ltd.
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  • 74
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    European journal of nutrition 36 (1997), S. 155-160 
    ISSN: 1436-6215
    Keywords: Detection method ; genetic engineering ; polymerase chain reaction ; processed food ; Gentechnik ; Nachweisverfahren ; Polymerasekettenreaktion ; verarbeitete Lebensmittel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Bier, Sojaöl, verarbeitete Tomaten- (Ketchup, Mark, Pizzatomaten, Schältomaten, Suppe) und Kartoffelprodukte (Pommes frites, Chips, Püree, Mehl, Stärke, Bratkartoffeln) sowie ein Enzympräparat (Natuphos) wurden mittels PCR daraufhin untersucht, ob ein Nachweis des Einsatzes der Gentechnik bei ihrer Herstellung möglich ist. PCR-fähige DNA ließ sich aus Pizzatomaten, Schältomaten, Pommes frites, Bratkartoffeln, Kartoffelmehl und Kartoffelchips isolieren, so daß der Nachweis des Einsatzes der Gentechnik bei deren Herstellung möglich wird. Bestimmte Biere (Pils, Export, Nutfield lyte), Sojaöl, Tomatensuppe, Kartoffelstärke, Kartoffelpüree und Natuphos entziehen sich einem solchen Nachweis, da die PCR-Analyse keine Hinweise auf das Vorliegen von DNA in diesen Produkten ergab. Daß das durchgeführte Nachweisverfahren grundsätzlich in der Lage ist, geringe Mengen an DNA auch in diesen Produkten spezifisch nachzuweisen, wurde nach Zugabe vonEscherichia coli DNA bestätigt.
    Notes: Summary To elucidate if there is any possibility to identify highly processed foods as produced through genetic engineering, beer, soya bean oil, processed tomato (ketch-up, paste, pizza tomatoes, peeled tomatoes, soup) and potato (french fries, crisps, mashed potatoes, flour, starch, fried potatoes) products as well as an enzyme preparation (Natuphos) were investigated by PCR. In pizza tomatoes, peeled tomatoes, french fries, fried potatoes, potato flour and potato crisps DNA suitable for PCR was found. Therefore, it is possible to identify these products as produced through genetic engineering. Such an identification is impossible in certain beers (pilsener, export, Nutfield lyte), soya bean oil, tomato soup, potato starch, mashed potatoes and Natuphos since PCR-analysis gave no indication of the presence of DNA in these products. As it was shown by addingEscherichia coli DNA the used method is, in principle, capable of detecting specifically small amounts of DNA in such products.
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  • 75
    ISSN: 1572-9818
    Keywords: Agrobacterium ; Populus ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In recent years, Populus species have acquired an important place in basic and applied research of woody plants. The practical role of Populus species in world forestry and their importance to research as a woody-plant model have led to increasing interest in tissue-culture and molecular techniques, as well as the development of transformation procedures for this genus. A simple technical procedure is described here step-by-step, for the first time, as a routine method for transforming Populus tremula using a disarmed Agrobacterium tumefaciens hypervirulent strain. The procedure begins with the inoculation of stem explants with bacterial suspension, followed by a short period of co-cultivation on a highly regenerative medium. Transformed shoots are selected on regeneration medium containing antibiotics and the presence of the inserted target genes is checked using a rapid and efficient PCR test. Selected shoots are transferred to a rooting medium, under the same selection pressure, and propagated via stem cuttings. Selected plants can be hardened and transferred to the green-house within 4 months of inoculation. The method has proven efficient for several gene constructs, selection on Kan or Hyg, and three different Agrobacterium strains.
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  • 76
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    Biodegradation 8 (1997), S. 97-103 
    ISSN: 1572-9729
    Keywords: Escherichia coli ; genetic engineering ; mercury bioaccumulation ; mercury transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ion exchange or biosorptive processes for metalremoval generally lack specificity in metal bindingand are sensitive to ambient conditions, e.g. pH,ionic strength and the presence of metal chelators. Inthis study, cells of a genetically engineered Escherichia coli strain, JM109, which expressesmetallothionein and a Hg2+ transport system afterinduction were evaluated for their selectivity forHg2+ accumulation in the presence of sodium,magnesium, or cadmium ions and their sensitivity to pHor the presence of metal chelators during Hg2+bioaccumulation. The genetically engineered E.coli cells in suspension accumulated Hg2+effectively at low concentrations (0-20 µM) overa broad range of pH (3 to 11). The presence of 400 mMsodium chloride, 200 mM magnesium chloride, or100 µM cadmium ions did not have a significanteffect on the bioaccumulation of 5 µm Hg2+,indicating that this process is not sensitive to highionic strength and is highly selective against sodium,magnesium, or cadmium ions. Metal chelators usuallyinterfere with ion exchange or biosorptive processes.However, two common metal chelators, EDTA and citrate,had no significant effect on Hg2+ bioaccumulationby the genetically engineered strain. These resultssuggest that this E. coli strain could be usedfor selective removal of Hg2+ from waste water orfrom contaminated solutions which are resistant tocommon treatments. A second potential applicationwould be to remove Hg2+ from Hg2+-contaminated soil, sediment, or particulates bywashing them with a Hg2+ chelator andregenerating the chelator by passing the solutionthrough a reactor containing the strain.
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  • 77
    ISSN: 1432-0428
    Keywords: Keywords Insulin ; genetic engineering ; cell lines ; transplantation ; molecular biology.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The recently completed diabetes complications and control trial has highlighted the need for improvement of insulin delivery systems for treatment of insulin-dependent diabetes mellitus. Despite steady improvement in methods for islet and whole pancreas transplantation over the past three decades, the broad-scale applicability of these approaches remains uncertain due in part to the difficulty and expense associated with procurement of functional tissue. To address this concern, we and others have been using the tools of molecular biology to develop cell lines with regulated insulin secretion that might serve as a surrogate for primary islets or pancreas tissue in transplantation therapy. This article seeks to provide a brief summary of the current status of this growing field, with a particular emphasis on progress in producing cell lines with appropriate glucose-stimulated insulin secretion. [Diabetologia (1997) 40: S 42–S 47]
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  • 78
    ISSN: 1432-2048
    Keywords: Agrobacterium ; Leaf mesophyll cells ; Petunia ; Transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chimeric β-glucuronidase (GUS) gene expression in an efficientAgrobacterium-mediated transformation system utilising mesophyll cells ofPetunia hybrida synchronized with cell cycle phase-specific inhibitors (mimosine and colchicine) was used to show the absolute requirement of S-phase for transfer and/or integration of the transferred DNA (T-DNA). Flow-cytometric analysis of nuclear DNA content and immunohistological detection of bromodeoxyuridine (BrdUrd) incorporation showed that, prior to phytohormone treatment, most (98%) mesophyll cells were at GO-Gl-phase (quiescent phase) and no cell division was occurring. After 48 h and 72 h of phytohormone treatment, there was a rapid increase in S-G2-M-phase populations (〉 75%) and a concomitant decrease (down to 24%) in G0–-G1-phase cells. Assays of GUS showed that maximum transformation (〉 95% of explants) also occurred after this period. Our data showed that mimosine and colchicine blocked the mesophyll cells at late Gl-phase and M-phase, respectively. No transformation (= GUS expression) was observed in phytohormone-treated cells inhibited in late G1 by mimosine. However, after removal of mimosine, 82% of the explants were transformed, indicating the non-toxic and reversible effect of the inhibitor. On the other hand, a relatively high transformation frequency (65% of explants) was observed after blocking the cell cycle at M-phase with colchicine. However, only transient, but no stable, gene expression (= kanamycin-resistant callus formation) was observed in colchicine-treated M-phase-arrested cells. Similarly, endoreduplication of nuclear DNA, which occurred during the 48 h of phytohormone treatment in some mesophyll cells and cells located along the minor veins in the leaf explants, resulted in transient GUS expression only. These observations indicate a direct correlation between endoreduplication and transient GUS gene expression. Obviously, for stable GUS gene expression, cell division and proliferation are required, indicating that both DNA duplication (S-phase) and cell division (M-phase) are strongly related to stable transformation. We propose that the present system should facilitate further dissection of the process of T-DNA integration in the host genome and therefore should aid in developing new strategies for transformation of recalcitrant plants.
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  • 79
    ISSN: 1432-203X
    Keywords: Transgenic peanut ; Agrobacterium ; Transformation ; Transgene expression ; Transgene inheritance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To evaluate and characterize the stability of traits transferred viaAgrobacterium transformation, foreign gene expression must be examined in sexually derived progeny. The objective of this study was to analyze three transgenic peanut plants, 1-10, 12-1, and 17-1, for the inheritance and expression of their foreign genes. Segregation ratios for the introduced genes in T2 plants gave either 100% or 3:1 expression of the β-glucuronidase (GUS) gene, demonstrating recovery of both homozygous and heterozygous T1 plants. Fluorometric GUS assay in T1 and T2 generations of all three plants showed that the GUS gene was stably expressed in the progeny. DNA analyses showed 100% concordance between the presence of the foreign gene and enzyme activity. Our results demonstrate that transgenes in peanut introduced byAgrobacterium can be inherited in a Mendelian manner.
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  • 80
    ISSN: 1432-072X
    Keywords: Key words 6-Methylnicotinic acid ; 2-Hydroxy-6-methylnicotinic acid ; Nicotinic acid ; 2-Hydroxynicotinic acid ; Ralstonia ; Burkholderia ; Paenibacillus ; Agrobacterium ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 2-Hydroxynicotinic acid is an important building block for herbicides and pharmaceuticals. Enrichment strategies to increase the chances of finding microorganisms capable of hydroxylating at the C2 position and to avoid the degradation of nicotinic acid via the usual intermediate, 6-hydroxynicotinic acid, were used. Three bacterial strains (Mena 23/3–3c, Mena 25/4–1, and Mena 25/ 4–3) were isolated from enrichment cultures with 6-methylnicotinic acid as the sole source of carbon and energy. Partial characterization of these strains indicated that they represent new bacterial species. All three strains completely degraded 6-methylnicotinic acid, and evidence is presented that the first step in the degradation pathway of strain Mena 23/3–3c is hydroxylation at the C2 position. Resting cells of this strain grown on 6-methylnicotinic acid also hydroxylated nicotinic acid at the C2 position, but did not further degrade the product. Strain Mena 23/ 3–3c showed the highest degree of 16S rRNA sequence similarity to members of the genera Ralstonia and Burkholderia.
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  • 81
    ISSN: 1573-5028
    Keywords: CaMV 35S promoter ; Catharanthus roseus ; FMV 34S promoter ; particle bombardment ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Activities of several CaMV 35S and FMV 34S promoter derivatives fused to the gusA reporter gene were compared in suspension-cultured Catharanthus roseus cells that were transiently and stably transformed using particle bombardment. Our data demonstrate that the 35S and a deletion derivative of the 34S promoter combined with particle bombardment form useful tools for genetic engineering of C. roseus cells. Our results disagree on several points with activities of 35S and 34S promoter derivatives reported for tobacco, indicating that absolute and relative promoter activities can differ between plant species.
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  • 82
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    Plant molecular biology 33 (1997), S. 1097-1103 
    ISSN: 1573-5028
    Keywords: Ac ; Agrobacterium ; periclinal chimera ; rolC ; transgenic Populus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The transposable element Ac from maize, in combination with the phenotypic selectable marker rolC, was employed in transformation experiments of a hybrid aspen clone. A number of transgenic clones exhibited light-green sectors on green leaves. In vitro regeneration from leaves showing a high number of light-green spots resulted in R2 plants, which also showed light-green sectored leaves. However, only one out of 385 regenerated plants obtained showed green leaves. Both PCR and northern analysis indicated Ac excision and restoration of rolC expression. In Southern blot analysis of this green plant additional bands were observed as compared to the original R1 plant. The occurrence of these bands and a suggested Ac excision in the non-green L1-epidermal layer leading to periclinal chimerism of this plant is discussed.
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  • 83
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    Plant cell reports 16 (1997), S. 363-367 
    ISSN: 1432-203X
    Keywords: Agrobacterium ; Tapetum-specific promoter ; Transformation ; Rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The promoter of an anther tapetum-specific gene,Osg6B, was fused to aβ-glucuronidase (GUS) gene and introduced into rice byAgrobacterium-mediated gene transfer. Fluorometric and histochemical GUS assay showed that GUS was expressed exclusively within the tapetum of anthers from the uninucleate microspore stage (7 days before anthesis) to the tricellular pollen stage (3 days before anthesis). This is the first demonstration of an anther-specific promoter directing tapetum-specific expression in rice.
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  • 84
    ISSN: 1432-203X
    Keywords: Key words Transgenic peanut ; Agrobacterium ; Transformation ; Transgene expression ; Transgene inheritance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To evaluate and characterize the stability of traits transferred via Agrobacterium transformation, foreign gene expression must be examined in sexually derived progeny. The objective of this study was to analyze three transgenic peanut plants, 1-10, 12-1, and 17-1, for the inheritance and expression of their foreign genes. Segregation ratios for the introduced genes in T2 plants gave either 100% or 3:1 expression of the β-glucuronidase (GUS) gene, demonstrating recovery of both homozygous and heterozygous T1 plants. Fluorometric GUS assay in T1 and T2 generations of all three plants showed that the GUS gene was stably expressed in the progeny. DNA analyses showed 100% concordance between the presence of the foreign gene and enzyme activity. Our results demonstrate that transgenes in peanut introduced by Agrobacterium can be inherited in a Mendelian manner.
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  • 85
    ISSN: 1573-9368
    Keywords: Ac ; Agrobacterium ; aspen ; Populus ; transformation ; transposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aspen (Populus tremula) and hybrid aspen (P. tremula × P. tremuloides) were transformed with different gene constructs using two types of promoter. The aim was to determine the influence of the reporter gene rolC, controlled by promoters of viral or plant origin, on genetic and morphologic expression of different transgenic aspen clones. An improved transformation method using leaf discs was developed, by which putative transgenic plantlets were regenerated at high efficiencies (up to 34%) on kanamycin-containing medium. Transgenic aspen carrying the rolC gene from Agrobacterium rhizogenes under control of the cauliflower-35S-promoter are reduced in size with smaller leaves, whereas aspen transgenic for the same rolC gene, but under control of the light inducible rbcS promoter from potato, are only slightly reduced in size compared to untransformed controls. However, all clones carrying 35S-rolC and rbcS-rolC genes revealed light-green colouration of leaves when compared to untransformed aspen. Owing to this special feature, constructs were used in which expression of the rolC gene was inhibited by insertion of a transposable element, Ac, from maize. Transgenic aspen transformed with the 35S-Ac-rolC and rbcS-Ac-rolC genes were morphologically similar to untransformed aspen, but out of 54 independently regenerated 35S-Ac-rolC transgenic aspen clones, 30 clones showed light-green/dark green variegated leaves. In contrast, out of 19 independently transformed rbcS-Ac-rolC aspen clones, only two clones revealed light-green/dark green variegated leaves. The role of bacterial strains in transformation, and molecular genetics of transgenic aspen plants (including the function of the transposable element, Ac, in the aspen genome) are discussed
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  • 86
    ISSN: 1573-9368
    Keywords: transgenic cotton ; bialaphos ; particle bombardment ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Resistance to bialaphos, a non-selective herbicide, was intro duced into cotton through genetic engineering. A gene encoding phosphinothric in acetyltransferase (bar) from Streptomyces hygroscopicus was inserted into elite varieties of cotton through particle bombardment. Based on the marker gene, β-glucuronidase (gus) expression, a total of 18 Pima (Gossypium barbadense), 45 DP50 (G. hirsutum L.), 20 Coker 312 (G. hirsutum) and 2 El Dorado (G. hirsutum) transgenic plants were recovered. Integration of the bar gene into cotton genomic DNA was confirmed by Southern blot analysis and gene expression was confirmed by northern blot and enzyme assays. Herbicide (Basta®) tolerance up to 15 000 ppm was demonstrated in greenhouse trials. The newly introduced herbicide tolerance trait is inherited in a Mendelian fashion in the progenies of germline transformants. This study demonstrates the potential for particle bombardment to introduce commerically important genes directly into elite varieties of cotton. This mode of gene transfer can expedite the introduction of transgenic cotton products into world markets
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  • 87
    ISSN: 1573-5117
    Keywords: transgenic fish ; gene transfer ; growth enhancement ; lopifection ; particle bombardment ; electroporation ; fish sperm ; fish embryos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recent advantages in transgenic fish research are reviewed, with special reference to the methods for gene transfer. These include microinjection, electroporation, particle bombardment, and lipofection. The success and problems associated with each of these methods, and the possible applications of transgenic fish research to aquaculture are discussed.
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  • 88
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    Plant and soil 196 (1997), S. 163-174 
    ISSN: 1573-5036
    Keywords: fertilizers ; food production ; genetic engineering ; macronutrients ; micronutrients ; nutrient absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper briefly presents the knowledge of plant nutrition in 1900 and its expansion since then in two areas - the discovery of the micronutrients and the absorption of nutrients from soils. Application of macro- and micronutrient fertilizers has contributed substantially to the huge increase in world food production experienced this century. In developed countries, excessive fertilizer use has led to serious problems of nutrient pollution; here, plant nutritionists will be concerned with monitoring nutrient status of crops and soils to maintain crop production with minimum loss of nutrients to the environment, and development of cultivars with high nutrient efficiency in soils with luxury supplies of nutrients. In many developing countries, soil infertility limits productivity; here, plant nutritional research can raise productivity by diagnosis of nutrient deficiencies and toxicities of crops on previously unfertilized soils, their correction with minimal fertilizer and treatment costs, and development of cultivars with high nutrient efficiency in deficient soils and high tolerance of natural toxicities. The pre-occupation of developed countries with pollution is blinding them to the urgent needs of developing countries for fertilizers and fertilizer research to increase crop production ha-1 as an alternative to clearing more land.
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  • 89
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    Plant molecular biology 35 (1997), S. 197-203 
    ISSN: 1573-5028
    Keywords: genetic engineering ; particle bombardment ; plant biotechnology ; transgenic rice ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bombardment-based methodology is responsible for the effective genetic manipulation of major cereals including rice. Many groups reported significant advances on various aspects of rice molecular biology and genetic engineering using procedures based on bombardment technology. Molecular and genetic characterization of large numbers of these plants (more than 500 independent transgenic plants) provided information on structure, expression and stability of integrated DNA through multiple generations. Such evaluations were carried out in the greenhouse and in the field. Stability of expression was found to be dependent on the nature of the promoter and the transgene, and in specific cases on gene copy number. Direct DNA transfer utilizing particle bombardment for the delivery of foreign DNA into rice tissue results in the recovery of large numbers of independently derived transgenic plants in a variety-independent fashion. Gene copy number, level and stability of expression of transgenes can be compared to other DNA delivery methods, direct or indirect, including Agrobacterium-mediated gene transfer. In this paper, the technology is summarized and discussed in terms of present and future applications, including field trials and potential commercialization of transgenic rice expressing a number of genes of agronomic interest such as pest and herbicide resistance.
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  • 90
    ISSN: 1573-5044
    Keywords: Agrobacterium ; coat protein ; grapevine ; hairy root ; nepovirus ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hairy root cultures of grapevine were obtained from plantlets co-inoculated by virulent Agrobacterium rhizogenes strains and disarmed A. tumefaciens strains harbouring the binary vectors pKHG4 and pKVHG 2+. These plasmids contain the nptII, hpt and gus genes and differ for the presence of the gene encoding for the grapevine chrome mosaic virus coat protein. For the cultivar ‘Gravesac’, 72% of the excised root tips initiated hairy root cultures on growth regulator-free media. According to the nature of the strains used in co-inoculation, co-transformation frequencies of the hairy root clones ranged from 4 to 16%. Co-transformed roots showed resistance to kanamycin and hygromycin but responses varied from clone to clone. Fluorometric GUS expression and GCMV coat protein production showed a large variability among hairy root clones co-transformed by pKHVG2+. Though the presence of gus, nptII and GCMV coat protein genes was checked by polymerase chain reaction and Southern blotting, it was difficult to establish a clear relationship between expression of the different transgenes. The regeneration of plants was not achieved, but the possibility to graft in vitro transgenic roots to non transformed shoot systems could permit rapid testing of the resistance induced by nepovirus coat protein in roots of cultivars that are recalcitrant to A. tumefaciens-mediated transformation.
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  • 91
    ISSN: 1573-5036
    Keywords: Agrobacterium ; Capparis spinosa ; Comamonas ; N2 fixation ; Pseudomonas ; rhizosphere ; Sphingobacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Four bacterial strains, Pseudomonas stutzeri var. mendocina, Comamonas sp., Agrobacterium tumefaciens biovar. 2 and Sphingobacterium sp., isolated from the rhizosphere of wild-grown caper (Capparis spinosa L.) plants were able to fix N2 as shown by their growth in nitrogen-free medium and by the acetylene reduction test. P. stutzeri var. mendocina and Comamonas sp. contained DNA homologous to the Klebsiella pneumoniae M5a1 nifHDK genes. No hybridization was found with total DNA from either A. tumefaciens biovar. 2 or Sphingobacterium sp. using nifHDK probes from either K. pneumoniae or Rhizobium meliloti.
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  • 92
    ISSN: 1573-5036
    Keywords: chloroplast ; genetic engineering ; nif genes ; nitrogenase ; plant transformation ; plastid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The engineering of plants capable of fixing their own nitrogen is an extremely complex task, requiring the co-ordinated and regulated expression of 16 nif genes in an appropriate cellular location. We suggest that plastids may provide a favourable environment for nif gene expression provided that the nitrogenase enzyme can be protected from oxygen damage. Using the non-heterocystous cyanobacteria as a model, we argue that photosynthesis could be temporally separated from nitrogen fixation in chloroplasts by restricting nitrogenase synthesis to the dark period. We report preliminary data on the introduction and expression of one of nitrogenase components, the Fe protein, in transgenic tobacco and Chlamydomonas reinhardtii. Finally we discuss potential avenues for further research in this area and the prospects for achieving the ultimate goal of expressing active nitrogenase in cereal crops such as rice.
    Type of Medium: Electronic Resource
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  • 93
    Electronic Resource
    Electronic Resource
    Springer
    Transgenic research 6 (1997), S. 329-336 
    ISSN: 1573-9368
    Keywords: Agrobacterium ; SAAT ; sonication ; transformation ; wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plant transformation via Agrobacterium can be limited by both host specificity and the inability of Agrobacterium to reach the proper cells in the target tissue. Described here is a new and efficient Agrobacterium-based transformation technology that overcomes these barriers and enhances DNA transfer in such diverse plant groups as dicots, monocots, and gymnosperms. This new technology, called sonication-assisted Agrobacterium-mediated transformation (SAAT), involves subjecting the plant tissue to brief periods of ultrasound in the presence of Agrobacterium. Scanning electron and light microscopy reveal that SAAT treatment produces small and uniform fissures and channels throughout the tissue allowing the Agrobacterium easy access to internal plant tissues. Unlike other transformation methods, this system has the potential to transform meristematic tissue buried under several cell layers. SAAT increases transient transformation efficiency in several different plant tissues including leaf tissue, immature cotyledons, somatic and zygotic embryos, roots, stems, shoot apices, embryogenic suspension cells and whole seedlings. A 100- to 1400-fold increase in transient β- glucuronid ase expression has been demonstrated in various tissues of soybean, Ohio buckeye, cowpea, white spruce, wheat and maize. Stable transformation of both soybean and Ohio buckeye has been obtained using SAAT of embryogenic suspension culture tissues. For soybean, SAAT treatment was necessary to obtain stable transformation with this tissue
    Type of Medium: Electronic Resource
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  • 94
    Electronic Resource
    Electronic Resource
    Springer
    Transgenic research 6 (1997), S. 379-383 
    ISSN: 1573-9368
    Keywords: genetic engineering ; heteroplasmy ; mouse ; mitochondria ; mitochondria transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method for mitochondria isolation and interspecific transfer of mitochondria was developed in mice. Mitochondria were isolated from Mus spretus liver samples for microinjection into fertilized ova obtained from superovulated M. musculus domesticus females. Electron microscopic observations of mitochondria preparations used for microinjection demonstrated intact mitochondrial vesicles with little microsomal contamination. Species-specific nested PCR primers complementary to sequence differences in the mitochondrial DNA D-loop region revealed high rates of successful transfer of foreign mitochondria after isolation and injection into zygotes cultured through the blastocyst stage of embryonic development. Of 217 zygotes, 67 survived mitochondria injection and 23 out of 37 zygotes developed were at the blastocyst-stage of embryonic development after 4.5 days of in vitro culture. All 23 of these blastocysts contained detectable levels of foreign mitochondria. These results represent an initial step in developing a model system to study mitochondrial dynamics and development of therapeutic strategies for human metabolic diseases affected by aberrations in mitochondrial function or mutation
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  • 95
    ISSN: 1573-9368
    Keywords: GUS ; matrix attachment regions ; Populus ; transformation ; transgene expression ; Agrobacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We tested the value of a matrix attachment region (MAR) fragment derived from a tobacco gene for increasing the frequency of Agrobacterium-mediated transformation. A binary vector that carried a GUS reporter gene containing an intron and an nptII gene was modified to contain flanking MAR elements within the T-DNA borders. Vectors containing or lacking MARs were then used to transform tobacco, a readily transformabl e poplar clone (Populus tremula × P. alba), and a recalcitrant poplar clone (Populus trichocarpa × P. deltoides). MARs increased GUS gene expression approximately 10-fold in the two hybrid poplar clones and twofold in tobacco one month after cocultivation with Agrobacterium; MARs also increased the frequency of kanamycin-resistant poplar shoots recovered
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  • 96
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 79 (1996), S. 309-315 
    ISSN: 1570-7458
    Keywords: insect resistance ; genetic engineering ; host specificity ; transgenic plant ; α-amylase inhibitor ; Callosobruchus spp. ; Zabrotes subfasciatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Various species of bruchid beetles including Callosobruchus chinensis, C. maculatus and C. analis cause postharvest damage of azuki bean seeds, an important East Asian grain legume. The α-amylase in the midguts of these insects is inhibited by the α-amylase inhibitor (αAI) present in common bean seeds. Transformation of azuki bean with the αAI gene driven by the promoter of phytohemagglutinin results in high levels of αAI in the seeds and the complete block of bruchid development on the seeds. Zabrotes subfasciatus, a South and Central American bruchid that is a storage pest of common bean, develops normally on the transgenic azuki bean.
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  • 97
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell reports 15 (1996), S. 727-730 
    ISSN: 1432-203X
    Keywords: Acetosyringone ; Agrobacterium ; Indica rice ; Oryza sativa L. ; Transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A reproducible system has been developed for the production of transgenic plants in indica rice using Agrobacterium-mediated gene transfer. Three-week-old scutella calli served as an excellent starting material. These were infected with an Agrobacterium tumefaciens strain EHA101 carrying a plasmid pIG121Hm containing genes for β-glucuronidase (GUS) and hygromycin resistnace (HygR). Hygromycin (50 mg/l) was used as a selectable agent. Inclusion of acetosyringone (50μM) in the Agrobacterium suspension and co-culture media proved to be indispensable for successful transformation. Transformation efficiency of Basmati 370 was 22% which was as high as reported in japonica rice and dicots. A large number of morphologically normal, fertile transgenic plants were obtained. Integration of foreign genes into the genome of transgenic plants was confirmed by Southern blot analysis. GUS and HygR genes were inherited and expressed in R1 progeny. Mendelian segregation was observed in some R1 progeny.
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  • 98
    ISSN: 1432-203X
    Keywords: Transformation ; particle bombardment ; Agrobacterium ; Allium cepa.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Particle bombardment and Agrobacterium-mediated DNA delivery into immature embryos and microbulbs were used to investigate the expression of the uidA gene in in vitro onion cultures. Both methods were successful in delivering DNA and subsequent uidA expression was observed. Optimal transient β-glucuronidase activity was observed in immature embryos that had been pre-cultured for three days and bombarded at a distance of 3 cm from the stopping plate, under 25 in Hg vacuum, using 900–1300 psi rupture discs. The CaMV35S-uidA gene construct gave five fold higher transient β-glucuronidase activity than the uidA gene construct regulated by any of four other promoters initially chosen for high experession in monocotyledonous tissues.
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  • 99
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 16 (1996), S. 129-133 
    ISSN: 1476-5535
    Keywords: extracellular polysaccharide ; Agrobacterium ; viscous polysaccharide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A bacterium isolated from soil and identified asAgrobacterium sp produced a water-soluble extracellular polysaccharide capable of producing highly viscous solutions. Gas chromatographic analysis revealed a sugar composition of glucose, galactose and mannose in the molar ratio of 7.5∶2.4∶1, together with 3.7% (w/w) pyruvic acid. Methylation analyses showed the presence of (1→3)-, (1→4)- and (1→6)-linked glucose, (1→3)- and (1→4, 1→6)-linked galactose and a small portion of (1→3)-linked mannose residues. Succinic acid was not present. The molecular weight of the polysaccharide was estimated by light scattering to be 2×106 Da. The viscosity of solutions containing the polysaccharide remained constant from pH 3 to 11, and decreased by 50% when heated from 5 to 55°C. Maximum yield of the polysaccharide, 20 g L−1, was reached in 48 h at 30°C incubation.
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  • 100
    ISSN: 1573-5028
    Keywords: cotton fiber ; transgenics ; particle bombardment ; fiber properties ; cDNA and genes ; nucleotide sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two genes, each corresponding to fiber mRNA E6, were isolated from cotton cultivars Coker 312 (Gossypium hirsutum L.) and Sea Island (G. barbadense L.). E6 is one of the predominant fiber-specific mRNAs present during early fiber development. The distinguishing feature of the nucleotide-derived E6 protein is the presence of a motif where a dimer, Ser-Gly, is repeated several times. Two of the Sea Island genes contained a pentameric motif, Ser-Gly, while one of the Coker genes had one and the other had four motifs each. cDNA clones containing one or five Ser-Gly motifs were also identified. Thus, it appears that the strict conservation of this motif may not be critical to E6 protein function. Sequence characterizations of the genes and cDNAs showed that multiple members of the E6 family are transcribed in fiber and may result in proteins 238 to 246 amino acids long. The 3′ ends of the genes and cDNAs showed considerable heterology among them. Transgenic plants containing antisense genes were generated to decipher E6 function. Transgenic cotton with reduced E6 protein levels in the range of 60 to 98% were identified. However, no discernible phenotypic changes in fiber development or properties were apparent. This result leads to the conclusion that E6 is not critical to the normal development or structural integrity of cotton fibers.
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