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  • 2000-2004  (19)
  • 1955-1959  (12)
  • 1920-1924
  • gene transfer
  • genetic engineering
  • somatic hybridization
  • 1
    ISSN: 1432-203X
    Keywords: Key words Rubber tree ; Agrobacterium tumefaciens ; calcium ; gene transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of CaCl2 was investigated on Agrobacterium tumefaciens-mediated gene transfer in Hevea brasiliensis friable calli which are usually proliferated on maintenance medium (MM) containing 9 mM CaCl2.Five A. tumefaciens strains (C58pMP90, C58pGV2260, AGL1, LBA4404 and EHA 105) and two binary vectors (pGIN and pCAMBIA2301) were tested and the strain EHA105pC2301 was selected to conduct further experiments. The calli were precultured on MM containing a range of CaCl2 concentrations, then inoculated with Agrobacterium suspension. Transfer of friable calli from MM containing 9 mM CaCl2 to calcium-free medium significantly enhanced the transient β-glucuronidase activity. Interestingly, the use of calcium-free Agrobacterium resuspension medium to inoculate friable calli again dramatically increased the transformation efficiency. Induction of Agrobacterium's virulence with acetosyringone remained an important factor to stimulate transformation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-4935
    Keywords: fusogenic peptides ; HA2 influenza virus hemagglutinin ; polylysine ; transfection ; gene transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Amphiphilic anionic peptides have been used to enhance the efficiency of transfection by helping plasmids to escape from endosomes to the cytosol. It has been shown that efficiency of an eicosamers containing five glutamyl residues (E5), can be considerably enhanced either by transforming it into a dimer or by adding a tripeptide WYG in a C-terminal position (E5WYG). The dimerization of the peptide E5WYG leads to a more efficient tool when the dimerization device includes the tripeptide WYG unit and a longer spacer arm made of Gly-βAla-βAla residues, but to a 10-fold less efficient tool when the dimerization device includes a shorter spacer, a glycyl residue. Both dimers are taken up by the cells to a similar extent. Both dimers seem to be surrounded similarly as far as the environmental pH is concerned. In contrast, we found a correlation between the propensity of the peptides to adopt a helical structure at neutral pH and the gene transfer efficiency.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Bioscience reports 20 (2000), S. 419-432 
    ISSN: 1573-4935
    Keywords: liposomes ; gene therapy ; gene transfer ; nonviral vectors ; polylysine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Synthetic gene transfer vectors based on polyplexes complexed to anionic liposomes (LPDII vectors) were characterized for their transfection efficiency in cultured mammalian cells. The effects of polycation to DNA ratio, lipid to DNA ratio, choice of polycation and lipid composition were systematically evaluated in human oral carcinoma KB cells, using a luciferase reporter gene. For LPDII formulations containing poly-L-lysine and dioeoylphosphatidylethanolamine/cholesteryl hemisuccinate (DOPE/CHEMS) anionic liposomes, at a constant lipid to DNA ratio, an increase in the polycation/DNA (N/P) ratio resulted in an increase in transfection activity. Meanwhile, the optimal lipid to DNA ratio for efficient gene delivery was influenced by the N/P ratio used, and was increased at higher N/P ratios. For the DNA condensing agent, poly-L-lysine could be replaced by polyethylenimine (PEI) as the DNA condensing agent in the formulations. For the lipidic components, CHEMS could be replaced by other anioniclipids including oleic acid, dicetylphosphate and phosphatidylserine, but DOPE, a fusogenic helper lipid, could not be replaced by dioleolyphosphatidylcholine. LPDII formulation showed significantly less cytotoxicity compared to the commonly used cationic lipsomes or PEI mediated transfection and several cell lines were transfected with high efficiency. LPDII vectors avoid the use of toxic cationic lipids and may have potential application in gene therapy.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1871-4528
    Keywords: tuber soft rot ; 2n gametes ; sexual hybridization ; somatic hybridization ; germplasm exploitation ; potato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The resistance to tuber soft rot caused byErwinia carotovora ofSolanum tuberosum x S. tarijense andS. tuberosum (+) S. commersonii hybrids and their backcrosses is reported. A number of resistant diploid sexual hybrids and tetraploid/hexaploid somatic hybrids were selected. Backcross progenies were obtained through 2x×4x crosses involving a resistant diploid hybrid and tetraploidS. tuberosum, and through 4x×4x crosses between a resistant somatic hybrid andS. tuberosum. The hybrids showed high variability interms of resistance to tuber soft rot. The resistance of progeny from 2x×4x backcrosses was similar to that of the parental sexual hybrid. By contrast, the resistance of genotypes deriving from 4x×4x backcrosses was reduced compared with the resistant somatic hybrid. In general, tuber characteristics of the backcross hybrids improved considerably as compared with their parents, and tuber yield per plant was good.
    Type of Medium: Electronic Resource
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  • 5
    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.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Biochemical genetics 38 (2000), S. 41-55 
    ISSN: 1573-4927
    Keywords: gene transfer ; liposome ; IGF-I ; wound healing ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Our hypothesis is that gene transfer of an IGF-I CMV-cDNA with cholesterol containing cationic liposomes is an efficient tool for transient transfection of growth factors in vitro and in vivo. In vitro, we transiently cotransfected IGF-I cDNA with a CMV construct and a Lac Z CHKβCHK-galactosidase cDNA/CMV construct using cholesterol containing cationic liposomes and measured CHKβCHK-galactosidase and IGF-I mRNA and protein. In vivo, we subcutaneously injected 3-month-old male Sprague–Dawley rats with IGF-I cDNA and CHKβCHK-galactosidase cDNA into rat skin. After IGF-I and CHKβCHK-galactosidase were cotransfected into PC12 cells, Northern blot analysis showed that the peak time of IGF-I expression was 2 days for mRNA and 5 days for protein. In vivo, a cDNA/liposome ratio of 1:2 was most effective. IGF-I protein expression in IGF-I-transfected skin resulted in significant transfection from day 5 to day 7. In situ determination of CHKβCHK-galactosidase activity confirmed that transfections resulted in a restricted expression area.
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  • 7
    ISSN: 1573-904X
    Keywords: gene transfer ; lipid emulsions ; poly(ethylene glycol) ; transfection ; cationic lipids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To develop a non-viral gene delivery system in the form ofan oil-in-water (o/w) lipid emulsionMethod. Cationic lipid emulsions were formulated with soybean oil,1,2-dioleoyl-sn-glycero-3-trimethylammonium-propane (DOTAP) as acationic emulsifier and other co-emulsifiers. The physicalcharacteristics of the lipid emulsion and the emulsion/DNA complex weredetermined. The in vitro transfection efficiency of the emulsion/DNAcomplex was determined in the presence of up to 90% serum. Results. The average droplet size and zeta potential of emulsions wereca. 180 nm and ca. +50 mV, respectively. Among the emulsions, astable formulation was selected to form a complex with a plasmidDNA encoding chloramphenicol acetyltransferase. By increasing theratio of emulsion to DNA, zeta-potential of the emulsion/DNA complexincreased monotonously from negative to positive without any changesin the complex size. The complex was stable against DNase I digestionand an anionic poly-l-aspartic acid (PLAA). The complex deliveredDNA into the cells successfully, and the transfection efficiency wasnot affected by complex formation time from 20 min to 2 h. Moreimportantly, the cationic lipid emulsion facilitated the transfer of DNAin the presence of up to 90% serum. Conclusions. The cationic lipid emulsion/DNA complex has physicalstability and serum resistant properties for gene transfer.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Reviews in endocrine & metabolic disorders 1 (2000), S. 205-215 
    ISSN: 1573-2606
    Keywords: Na+/I- symporter ; expression ; promoter ; gene transfer ; radioiodide therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
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    Springer
    Antonie van Leeuwenhoek 78 (2000), S. 323-329 
    ISSN: 1572-9699
    Keywords: gene transfer ; plasmids ; Streptomyces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Studies were made of naturally occurring plasmids hosted in Streptomyces strains isolated from two different terrestrial ecosystems: an agricultural field and a protected forest area. Six out of the 147 screened isolates contained plasmids. The strains containing these plasmids were all isolated from the agricultural soil. Plasmids were not found among the strains isolated from the forest area. Cross hybridization of the six newly isolated plasmids revealed very high similarities between four of them. However, no similarities were found between the six newly isolated plasmids and well studied streptomycete plasmids such as pIJ101 and SCP2*. The host strains of the four similar plasmids belonged to three different species S. anulatus, S. rochei and S. diastaticus. This implies a possible conjugative transfer of these plasmids within the streptomycete population in the agricultural area. The reason for the absence of streptomycete plasmids from the populations derived from the forest area is discussed.
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  • 10
    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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  • 11
    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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  • 12
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
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  • 13
    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.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
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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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  • 15
    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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  • 16
    Electronic Resource
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    Springer
    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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  • 17
    Electronic Resource
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    Springer
    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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  • 18
    ISSN: 1573-904X
    Keywords: liposomes ; cancer vaccines ; cytokines ; immunotherapy ; interferon gamma ; gene transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Liposomal systems may be useful as a cytokine supplementin tumor cell vaccines by providing a cytokine reservoir at the antigenpresentation site. Here, we examined the effect of liposomeincorporation of mIFNγ on its potency as adjuvant in an established tumor cellvaccination protocol in the murine B16 melanoma model. Adjuvanticityof the mIFNγ-liposomes was compared to that achieved bymIFNγ-gene transfection of the B16 tumor cells. Furthermore, we studiedwhether liposomal incorporation of mIFNγ indeed increases theresidence time of the cytokine at the vaccination site. Methods. C57B1/6 mice were immunized with i) irradiated IFNγ-genetransfected B16 melanoma cells or ii) irradiated wild type B16 cellssupplemented with (liposomal) mIFNγ, followed by a challenge withviable B16 cells. The residence time of the (liposomal) cytokine at thesubcutaneous (s.c.) vaccination site was monitored using radiolabeledmIFNγ and liposomes. Results. Immunization with irradiated tumor cells admixed withliposomal mIFNγ generated comparable protection against B16 challenge asimmunization with mIFNγ-gene modified tumor cells. Irradiated tumorcells admixed with soluble mIFNγ did not generate any protectiveresponses. Radiolabeling studies indicated that free mIFNγ rapidlycleared from the s.c. injection site. Association of [125I]-mIFNγwith liposomes increased the local residence time substantially: liposomalassociation of mIFNγ resulted in a prolonged local residence time ofthe cytokine as reflected by a 4-fold increase of the area under thecurve. The amount of released cytokine in the optimal dose rangecorresponds to the amount released by the gene-transfected cells. Moderate but significant CTL-activity against B16 cells was found for miceimmunized with irradiated cells supplemented with mIFNγ-liposomescompared to untreated control animals. Conclusions. Prolonged presence of mIFNγ at the site of antigenpresentation is crucial for the generation of systemic immune responsesin the B16 melanoma model. These studies show that liposomalencapsulation of cytokines is an attractive strategy for paracrine cytokinedelivery in tumor vaccine development.
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  • 19
    ISSN: 1573-9368
    Keywords: gene transfer ; selectable marker ; adenosine analogues ; transgenic maize ; adenosine deaminase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A murine adenosine deaminase (ADA) gene, driven by the maize ubi-1 promoter and intron region, was transformed into embryogenic maize callus, along with a bar and gusA gene-containing plasmid, using microparticle bombardment. Selection in the presence of either the herbicide Basta® or the adenosine analogue 2′-deoxyadenosine resulted in transgenic cultures that expressed GUS and accumulated a 41kD protein that immunoprecipated with an ADA-specific polyclonal antibody. ADA enzyme activity was observed in extracts from transgenic callus as well as regenerated plants and progeny. Cultures expressing ADA grew in the presence of 200mg/l 2′-deoxyadenosine, a concentration which completely inhibited the growth of non-transgenic cultures. ADA activity appeared to segregate in progeny of regenerated plants as a single, dominant Mendelian trait. These results suggest that ADA, in combination with adenosine analogue selection, represents a potentially viable selectable marker system for transgenic maize production.
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  • 20
    ISSN: 1573-5060
    Keywords: protoplasts ; protoclonal variation ; somatic hybridization ; top-fruit trees ; woody ornamentals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Until recently, temperate fruit trees and woody ornamentals have been regarded as recalcitrant to biotechnological breeding approaches based on protoplasts. This however should no longer be the case, as procedures are now available, not only for the regeneration of complete plants from protoplasts of various tissues of such species, but also for the exploitation of protoplast technology for their genetic manipulation. This paper will examine the recent advances and state of the art in this domain, with particular attention to the use of protoplast technology as a novel tool in the breeding of rosaceous top-fruit tree species and woody ornamentals. Problems and their solutions within the context of regenerating plants from isolated protoplasts of stone (Prunus spp.), pome (Pyrus spp., Malus spp.) and small (Rubus spp.) fruits, and of several shrubby ornamental genotypes (Lonicera spp., Weigela spp., Forsythia spp., Cotoneaster spp.) will be addressed. Interspecific (Prunus spinosa + Prunus cerasifera) and intergeneric (Forsythia spp. + Syringa spp.) somatic hybridization within this group of species, as well as the use of protoplasts for host/pathogen interaction studies (Pyrus/Erwinia amylovora) will also be discussed.
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  • 21
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    Euphytica 85 (1955), S. 217-233 
    ISSN: 1573-5060
    Keywords: crop improvement ; alien gene transfer ; progeny analysis ; somatic hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In recent years, the rapid development of somatic cell genetics has made possible the transfer of alien genes over wide taxonomic distances by somatic hybridization. In this review, the potential of somatic hybridization in the breeding of crops within the Brassicaceae, Fabaceae, Poaceae and Solanaceae is discussed. It is evident from these studies that many hybrids, either symmetric or asymmetric, which are fertile have the potential to be used as a bridge between the alien species and the crop. Progeny analysis of some hybrid combinations also reveals intergenomic translocations which may lead to the introgression of the alien genes. Furthermore, fusion techniques enable the resynthesis of allopolyploid crops to increase their genetic variability and to restore ploidy level and heterozygosity after breeding at reduced ploidy level in polyploid crops.
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  • 22
    ISSN: 1573-5060
    Keywords: meristem ; shoot apex ; ballistic microtargeting ; gene transfer ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The classical approach of gene transfer to a given plant species delivers the foreign gene to transformable cells and then puts the effort into generating plants. This approach is very difficult in many important crop plants, including cereals, and the results of regeneration are very genotype-dependent. In contrast, we use regenerable cells and try to transform them. Shoot apical meristems provide a tissue which regenerates in situ a fertile plant for most given genotypes or species. Transformation of meristem cells may lead to transgenic sectors in chimeras. These sectors may contribute to the gametes and, thus, to transgenic offspring, which then should be homohistonts and not sectorial chimeras like their parents. Our model plant for these studies is wheat. Microtargeting is a ballistic approach which is particularly suitable for the controlled delivery of microprojectiles to meristem cells in situ (Sautter et al., 1991). We summarize in this paper our experience with ballistic microtargeting of transgenes to wheat shoot apical meristem cells in situ.
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  • 23
    ISSN: 1573-5060
    Keywords: gene transfer ; Hordeum vulgare ; neomycin phosphotransferase II ; particle bombardment ; transgenic barley
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Transgenic barley plants (Hordeum vulgare L. cv. Kymppi) were obtained by particle bombardment of various tissues. Immature embryos and microspore-derived cultures were bombarded with gold particles coated with plasmid DNA carrying the gene coding for neomycin phosphotransferase II (NPTII), together with plasmid DNA containing the gene for β-glucuronidase (GUS). Bombarded immature embryos were grown to plants without selection and NPTII activity was screened in small plantlets. One plant proved to be transgenic (T0). This chimeric plant passed the transferred nptII gene to its T1 progeny. The presence of the nptII gene was demonstrated by the PCR technique and enzyme activity was analyzed by an NPTII gel assay. Four T0 spikes and 15 T1 offspring were transgenic. The integration and inheritance was confirmed by Southern blot hybridization. Transgenic T2 and T3 plants were produced by isolating embryos from green grains of transgenic T1 and T2 plants, respectively and growing them to plants. After selfing, the ratio of transgenic to non-transgenic T2 offspring was shown to follow the rule of Mendelian inheritance. The general performance of transgenic plants was normal and no reduction in fertility was observed. Microspore-derived cultures were bombarded one and four weeks after microspore isolation. After bombardment, cultures were grown either with or without antibiotic selection (geneticin R or kanamycin). When cultures were grown without selection and regenerated plants were transferred to kanamycin selection in rooting phase, one out of a total of about 1500 plants survived. This plant both carried and expressed the transferred nptII gene. The integration was confirmed by Southern blot hybridization. This plant was not fertile.
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  • 24
    ISSN: 1573-5060
    Keywords: Oryza sativa ; Indica-type rice ; genetic engineering ; vitamin A endosperm ; insect resistance ; virus resistance ; fungus resistance ; essential amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Indica-type rice provides the staple food for two billion people in Third World countries. Several problems involved in the stable and sustained production of high quality food cannot be solved by traditional breeding. Methods have been established for gene transfer to Indica rice breeding lines to study possible contributions from genetic engineering. Experiments are in progress on the development of transgenic resistance towards Yellow Stem Borer, resistance towards Rice Tungro Virus, accumulation of provitamin A in the endosperm, increase of essential amino acids in the endosperm such as lysine, cysteine and methionine and resistance towards fungal pests such as Rice Blast and Sheath Blight. Transgenic clones from Indica rice breeding lines have been recovered from several of the approaches mentioned, some of which have been regenerated to plants.
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  • 25
    ISSN: 1573-5060
    Keywords: genetic engineering ; introgression ; molecular markers ; potatoes ; resistances ; Solanum ; technology mansfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potato genetic improvement has been facilitated using new knowledge of potato reproductive biology and new techniques. Many wild diploid species as well as landrace cultivars have been used in breeding at the diploid level, a strategy which is supported by 1) 2n gametes and 2) haploids from tetraploid cultivars. Different categories of wild species which have been under-utilized are now being exploited further in more systematic enhancement programmes using semi-conventional and biotechnological methods. Molecular maps of the potato genome are used actively to achieve marker-assisted introgression and improved selection among the germplasm collections to facilitate the use of valuable wild genetic resources. As an alternative method to incorporate a high level of fesistance, genetic engineering has been employed to facilitate the initial breeding process using various gene constructs for controlling major biotic stresses in the world.
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  • 26
    ISSN: 1573-5060
    Keywords: Solanum tuberosum ; somatic hybridization ; regeneration ; asymmetric fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This paper reviews investigations into the application of protoplast fusion to the genetic and agronomic improvement of potato. Fusion studies involving Solanum tuberosum are reviewed under the categories of: fusion with wild relatives, dihaploid fusion and asymmetric strategies. The selection and characterisation of putative somatic hybrid material is identified as a critical stage in the process and certain specific aspects of this technology are identified. Future prospects for the wider uptake and integration of these techniques into breeding programmes are also discussed.
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  • 27
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 85 (1955), S. 1-12 
    ISSN: 1573-5060
    Keywords: genetic engineering ; gene targets ; mapping ; markers ; transformation ; QTLs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
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  • 28
    ISSN: 1573-5060
    Keywords: Lactuca sativa ; Lactuca virosa ; Lactuca tatarica ; Lactuca perennis ; Iettuce ; sexual hybridization ; embryo rescue ; somatic hybridization ; protoplast fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Various genes for disease resistance identified in wild Lactuca are difficult, even impossible to exploit in lettuce breeding, due to sexual incompatibility between L. sativa and wild Lactuca sp. We adapted two cellular biology techniques to overcome these interspecific barriers: in vitro embryo rescue and protoplast fusion. In vitro rescue of immature embryos was used successfully for sexual hybridization between L. sativa and L. virosa. Vigorous hybrid plants were produced between L. sativa and seven accessions of L. virosa. Protoplast fusion permitted the regeneration of somatic hybrids between L. sativa and either L. tatarica or L. perennis. Hybrids between L. sativa and L. tatarica were backcrossed to L. sativa.
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  • 29
    ISSN: 1573-5060
    Keywords: Linum usitatissimum ; linseed ; mutation breeding ; somaclonal variation ; fatty acids ; genetic engineering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In the early 1980s the phenomenon of somaclonal variation induced by cell culture was exploited to produce genetic variation in linseed. The linseed variety Andro, derived from the widely grown Canadian variety McGregor, was selected in saline culture and was released for production in Canada. ‘Andro’ possesses traits very different from its parent, such as increased seedling vigour and tolerance to heat stress. Additional stable somaclonal variation in characters such as yield, days to maturity, seed weight and oil content were subsequently induced in ‘McGregor’. However, despite extensive screening of the somaclonal variants, no significant variation in the fatty acid profile was found. Chemical mutagenesis using ethyl methanesulphonate was, however, succesful in modifying the fatty acid profile of McGregor. Initial screening of M2 seed by the thiobarbituric acid colourimetric procedure was followed by gas chromatography to select half-seeds with atypical fatty acid profiles. Two independent, partially dominant genes were identified that were responsible for reducing the linolenic acid (18 : 3) from 50% to 2% while increasing linoleic acid (18 : 2) to 70%. A single, partially dominant gene, inherited independently of the linolenic acid genes, increased palmitic acid (16 : 0) from 7% to 30% and palmitoleic acid (16 : 1) from trace amounts to 4%. Agrobacterium-mediated transformation of linseed has also been successful. Herbicide tolerance genes for glyphosate, sulfonylurea and phosphinothricin have been incorporated into Canadian varieties. Commercially useful levels of tolerance to sulfonylurea herbicides have been achieved with no adverse agronomic affect. It is expected that a transgenic variety containing this resistance will be registered for commercial production in Canada in 1994. Standard breeding techniques, the application of antisense technology and the overexpression of fatty acid synthesis genes are being used to further modify the fatty acid profile of linseed, as well as for the transfer of abiotic stress-related genes identified in bromegrass.
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  • 30
    ISSN: 1573-5060
    Keywords: Vicia narbonensis ; gene transfer ; gene expression ; seeds ; 2S albumin ; methionine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Epicotyl explants were co-cultivated with Agrobacterium tumefaciens EHA101 to transfer a chimeric 2S albumin gene construct carried in the binary Ti plasmid vectors pGSGLUC1 or pGA472 into the grain legume Vicia narbonensis. This gene encoding the sulphur-rich Brazil nut albumin was under the control of either the CaMV 35S promoter which permits gene expression in all organs, or the Vicia faba legumin B4 promoter which elicits seed-specific gene expression. After callus formation and selection for kanamycin resistance, somatic embryos were induced which, in the case of transformation with the vector pGSGLUC1, were screened for GUS activity. Embryos that produced GUS were in addition analysed for 2S albumin formation. Selected transgenic embryos were cloned by multiple shoot regeneration. Rooted and fertile plants were obtained by grafting transgenic shoots on the appropriate seedlings. R1 and R2 generations were raised and analysed for GUS as well as 2S albumin gene expression. Expression of the 35S promoter/2S albumin gene fusion took place in all organs of the transgenic plants including the cotyledons of seeds, whereas seed-specific gene expression was found in transformants with the legumin promoter/2S albumin gene fusion. The 2S albumin accumulated in the 2S protein fraction of transgenic seeds and its primary translation product was processed into the 9 and 3 kDa polypeptide chains. The foreign protein was localised in the protein bodies of the grain legume. Analysis of the R2 plants indicated Mendelian inheritance of the 2S albumin gene. In homozygous V. narbonensis plants the amounts of 2S albumin were twice that present in the corresponding heterozygous plants. Whereas only low level formation of the foreign protein was achieved if the gene was under the control of the 35S promoter, approximately 3.0% of the soluble seed protein was 2S albumin if seed-specific gene expression was directed by the legumin B4 promoter. Some of these transformants exhibited a three-fold increase in the methionine content of the salt-soluble protein fraction extracted from seeds.
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  • 31
    ISSN: 1573-5060
    Keywords: gene transfer ; crop species ; particle bombardment ; transgenic plants ; cereals ; legumes ; woody plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The limiting component in the creation of transgenic crops has been the lack of effective means to introduce foreign genes into elite germplasm. However, the development of novel direct DNA transfer methodology, by-passing limitations imposed by Agrobacterium-host specificity and cell culture constraints, has allowed the engineering of almost all major crops, including formerly recalcitrant cereals, legumes and woody species. The creation of transgenic rice, wheat, maize, barley, oat, soybean, phaseolus, peanut, poplar, spruce, cotton and others, in an efficient and in some cases, variety-independent fashion, is a significant step towards the routine application of recombinant DNA methodology to the improvement of most important agronomic crops. In this review we will focus on key elements and advantages of particle bombardment technology in order to evaluate its impact on the accelerated commercialization of products based on agricultural biotechnology and its utility in studying basic plant developmental processes and function through transgenesis. Fundamental differences between conventional gene transfer methods, utilizing Agrobacterium vectors or protoplast/suspension cultures, and particle bombardment will be discussed in depth.
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