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  • Electronic Resource  (38)
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  • 1993  (38)
  • protoplasts
  • transformation
  • 1
    Electronic Resource
    Electronic Resource
    Stable transformation of the food yam Dioscorea alata L. by particle bombardment (1993)
    Springer
    Plant cell reports 12 (1993), S. 468-473 
    Details
    ISSN: 1432-203X
    Keywords: Dioscorea alata ; GUS ; transformation ; particle gun
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A biolistic particle gun was used to deliver genetic material into intact yam cells. Cultured suspension cells of D. alata were bombarded with microprojectiles coated with pBI221.2 DNA and histochemical assays were carried out to show transient GUS expression in bombarded cells. Stably transformed D. alata cells were recovered from cultured cells after bombardment with microprojectiles coated with pRT99gus harbouring both the nptII and uidA genes. Bombarded cells were selected on a medium containing geneticin (G418). Two months after bombardment, calli resistant to G418 were assayed for GUS expression. There was a 100% correlation between resistance to G418 and GUS expression. From these calli, four cell lines were established and GUS activity in each line was determined fluorometrically. The use of a specific GUS inhibitor showed that the GUS activity was due to the introduced uidA gene rather than to any intrinsic GUS-like activity originating from the plant. Incorporation of the introduced DNA into the plant genomic DNA was confirmed by Southern analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234714
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  • 2
    Electronic Resource
    Electronic Resource
    Enhanced transformation of tomato co-cultivated with Agrobacterium tumefaciens C58C1Rifr::pGSFR1161 in the presence of acetosyringone (1993)
    Springer
    Plant cell reports 12 (1993), S. 422-425 
    Details
    ISSN: 1432-203X
    Keywords: Acetosyringone ; Agrobacterium tumefaciens ; tomato ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Explants of tomato (Lycopersicon esculentum Mill cv. Ailsa Craig) were co-cultivated with Agrobacterium tumefaciens C58C1Rifr::pGSFR1161 in the presence of 20 (μM acetosyringone). Transformed root clones were selected on kanamycin medium and the presence of the nptII gene in the plant DNA confirmed by the polymerase chain reaction. Root clones derived from acetosyringone treatment grew more vigorously in the presence of kanamycin and synthesized a greater amount of NPT-II enzyme. The conclusion is that acetosyringone treatment enhances the transformation process, possibly by stimulating multiple insertions of the T-DNA into the host genome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234705
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  • 3
    Electronic Resource
    Electronic Resource
    Transformation of maize (Zea mays L.) protoplasts and regeneration of haploid transgenic plants (1993)
    Springer
    Plant cell reports 13 (1993), S. 63-68 
    Details
    ISSN: 1432-203X
    Keywords: Zea mays L ; microspore-derived cultures ; haploid ; regeneration ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transgenic haploid maize (Zea mays L.) plants were obtained from protoplasts isolated from microspore-derived cell suspension cultures. Protoplasts were electroporated in the presence of plasmid DNA containing the gus A and npt II genes encoding ß-glucuronidase (GUS) and neomycin phosphotransferase II (NPT II), respectively. Transformed calli were selected and continuously maintained on kanamycin containing medium. Stable transformation was confirmed by enzyme assays and DNA. analysis. Stably transformed tissue was transferred to regeneration medium and several plants were obtained. Most plants showed NPT II activity, and some also showed GUS activity. Chromosome examinations performed on representative plants showed that they were haploid. As expected, these plants were infertile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235291
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  • 4
    Electronic Resource
    Electronic Resource
    Selection of anthocyanin-accumulating potato (Solanum tuberosum L.) cell lines from calli derived from seedlings produced by gamma-irradiated seeds (1993)
    Springer
    Plant cell reports 12 (1993), S. 555-558 
    Details
    ISSN: 1432-203X
    Keywords: Solanum tuberosum ; anthocyanins ; gamma-irradiation ; protoplasts ; protoclones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Callus cell lines of potato (Solanum tuberosum L. cv. Zarevo) were obtained from seedlings germinated from gamma-irradiated seeds (200 Gy). Some of these cell lines produce red-violet pigments which were identified as acylated anthocyanins. The major anthocyanin was determined to be peonidin 3-O-[6-O-(4-O-E-p-coumaroyl-rhamnosyl)-glucoside]-5-O-glucoside (“peonanin”). Single cell-derived protoclones from non-pigmented protoplasts sometimes also gave rise to pigmented cell clusters thus indicating that the changes in the expression of the anthocyanin pathway can also occur after the stage of initial callus induction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233059
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  • 5
    Electronic Resource
    Electronic Resource
    Plant regeneration from mesophyll-protoplasts of four different ecotypes and two marker lines from Arabidopsis thaliana using a unique protocol (1993)
    Springer
    Plant cell reports 12 (1993), S. 569-572 
    Details
    ISSN: 1432-203X
    Keywords: Arabidopsis thaliana ; ecotypes and mutant lines ; protoplasts ; plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A protocol for obtaining regenerated fertile plants from mesophyll protoplasts of four ecotypes (Col C24, Per-1, Bur-0, Landsberg erecta) and two marker lines (M4 and M10) of Ardbidopsis thaliana is described. The different lines showed plating efficiencies between 1.0 and 3.9% using Nitsch medium or this medium supplemented with coconut water. For the differentiation of callus into normal shoots a single shoot regeneration medium was applicable to all ecotypes, but depending on the line other regeneration media showed to be more suitable. The results indicated that the protoplast culture procedure is applicable, with minor modifications, to all tested genotypes but the most suitable shoot regeneration medium should be established for each A. thaliana line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233062
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  • 6
    Electronic Resource
    Electronic Resource
    Fertile plant regeneration from protoplasts of meadow fescue (Festuca pratensis Huds.) (1993)
    Springer
    Plant cell reports 12 (1993), S. 95-100 
    Details
    ISSN: 1432-203X
    Keywords: forage grasses ; Festuca pratensis ; suspension cultures ; protoplasts ; plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Suspension cultures from mature embryo-derived compact callus were initiated in seven meadow fescue (Festuca pratensis Huds.) cultivars. Four to six months after initiation, embryogenic suspension cultures with a moderate growth rate were established from three of them (cvs. Barmondo, Belimo and Leopard). These suspension cultures showed the capacity, maintained over six months, to regenerate green plants which could be grown to maturity under greenhouse conditions. Morphogenic suspension cultures from single genotypes of three F. pratensis cultivars (cvs. Barmondo, Belimo and Leopard) yielded large numbers of protoplasts, which upon culture in agarose beads using nurse cells formed microcalli with an overall plating efficiency in the range of 10-3 to 10-4. Mature plants were reproducibly regenerated and established in soil, from such protoplasts during a period of six months. The regeneration of fertile plants from protoplasts derived from suspension cultures of meadow fescue and its implications on gene transfer technology for this species are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241942
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis of genetic stability of plants regenerated from suspension cultures and protoplasts of meadow fescue (Festuca pratensis Huds.) (1993)
    Springer
    Plant cell reports 12 (1993), S. 101-106 
    Details
    ISSN: 1432-203X
    Keywords: Festuca pratensis ; suspension cultures ; protoplasts ; plant regeneration ; somaclonal variation ; genetic fidelity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cytological and molecular analysis was performed to assess the genetic uniformity and true-to-type character of plants regenerated from 20 week-old embryogenic suspension cultures of meadow fescue (Festuca pratensis Huds.), and compared to protoplastderived plants obtained from the same cell suspension. Cytological variation was not observed in a representative sample of plants regenerated directly from the embryogenic suspensions and from protoplasts isolated therefrom. Similarly, no restriction fragment length polymorphisms (RFLPs) were detected in the mitochondrial, plastid and nuclear genomes in the plants analyzed. Randomly amplified polymorphic DNA markers (RAPDs) have been used to characterise molecularly a set of mature meadow fescue plants regenerated from these in vitro cultures. RAPD markers using 18 different short oligonucleotide primers of arbitrary nucleotide sequence in combination with polymerase chain reaction (PCR) allowed the detection of pre-existing polymorphisms in the donor genotypes, but failed to reveal newly generated variation in the protoplast-derived plants compared to their equivalent suspensionculture regenerated materials. The genetic stability of meadow fescue plants regenerated from suspension cultures and protoplasts isolated therefrom and its implications on gene transfer technology for this species are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241943
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of 1,2-benzisoxazole-3-acetic acid on plant regeneration from protoplasts of Nicotiana tabacum (1993)
    Springer
    Plant cell reports 12 (1993), S. 121-124 
    Details
    ISSN: 1432-203X
    Keywords: Auxin ; benzisoxazole-3-acetic acid ; protoplasts ; plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Benzisoxazole-3-acetic acid, a new synthetic growth regulator, was administered to protoplast cultures from Nicotiana tabacum and subsequently to the developed microcalluses, to test its activity on plant regeneration from protoplasts in different culture conditions. Such activity, compared to that of naphthalene-acetic acid, proved to be rather low in the stage of cellular division and microcallus formation but particulary high in the stage of shoot induction from microcallus, thus confirming that the activity of this compound is mainly morphogenetic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239090
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  • 9
    Electronic Resource
    Electronic Resource
    Somatic embryogenesis and plant regeneration from hypocotyl protoplasts of sunflower (Helianthus annum L.) (1993)
    Springer
    Plant cell reports 12 (1993), S. 260-263 
    Details
    ISSN: 1432-203X
    Keywords: sunflower ; protoplasts ; somatic embryogenesis ; plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A sunflower genotype (Helianthus annuus L. cv. Florom-328) able to regenerate plants from in vitro cultures was identified by screening hybrids and inbred lines. Protoplasts of this genotype were isolated from dark grown hypocotyls and were cultured in droplets of agarose-solidified V-KM medium covered by liquid V-KM supplemented with naphthaleneacetic acid (NAA) and benzylaminopurine (BAP). One week later colonies were subjected to 2,4-dichlorophenoxyaceticacid for a one week period. Further culture in V-KM with reduced concentrations of NAA and BAP resulted in the appearence of somatic embryos. Maturation of embryos was achieved by culture on MS medium supplemented with NAA, BAP, gibberellic acid A3 and the ethylene inhibitor AgNO3. Embryos were then transferred onto hormone free MS medium for germination. The frequency of shoot formation in the best case was 9.6 percent of viable colonies (1.3 percent of protoplasts plated). Some of the shoots with roots could be transplanted into soil, others were grafted on hypocotyls of in vivo germinated seedlings. Eighty percent of grafted shoots and over 95 percent of rooted shoots survived. The plants flowered and produced 5 to 10 seeds each. Factors affecting the frequency of embryo formation and plant regeneration are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237131
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  • 10
    Electronic Resource
    Electronic Resource
    Semi-constitutive expression of an Arabidopsis thaliana α-tubulin gene (1993)
    Springer
    Plant molecular biology 21 (1993), S. 937-942 
    Details
    ISSN: 1573-5028
    Keywords: α-tubulin ; Arabidopsis ; β-glucuronidase ; gene expression ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Arabidopsis tissues, the pool of tubulin protein is provided by the expression of multiple α-tubulin and β-tubulin genes. Previous evidence suggested that the TUA2 α-tubulin gene was expressed in all organs of mature plants. We now report a more detailed analysis of TUA2 expression during plant development. Chimeric genes containing TUA2 5′-flanking DNA fused to the β-glucuronidase (GUS) coding region were used to create transgenic Arabidopsis plants. Second-generation progeny of regenerated plants were analyzed by histochemical assay to localize GUS expression. GUS activity was seen throughout plant development and in nearly all tissues. The blue product of GUS activity accumulated to the highest levels in tissues with actively dividing and elongating cells. GUS activity was not detected in a few plant tissues, suggesting that, though widely expressed, the TUA2 promoter is not constitutively active.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027126
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  • 11
    Electronic Resource
    Electronic Resource
    Conditional inhibition of β-glucuronidase expression by antisense gene fragments in petunia protoplasts (1993)
    Springer
    Plant molecular biology 23 (1993), S. 45-55 
    Details
    ISSN: 1573-5028
    Keywords: Key words ; antisense RNA ; β-glucuronidase ; protoplasts ; transient gene expression ; PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Antisense RNA-mediated inhibition of gene expression is a valuable tool to induce mutant phenotypes. We are interested in the application of antisense gene fragments with the aim to improve the efficiency of inhibition and to be able to selectively suppress gene family members in plants. Protoplasts may provide a rapid system to screen the efficiency of antisense gene segments. As a first step, we set up a transient expression system for leaf protoplasts of Petunia hybrida and used as a model system the inhibition of β-glucuronidase (uidA) expression by uidA antisense gene segments. Both GUS enzyme activities and uidA RNA levels were measured. Co-introducing equal amounts of a full-length uidA antisense gene and a uidA sense gene reduced GUS activity by 60–70%. Various uidA antisense fragments also inhibited expression although with different efficiencies and we show that strong antisense fragments can be retrieved from weak antisense gene fragments. A promoter-less antisense gene did not reduce uidA expression indicating that the inhibition is mediated by antisense transcripts. Using quantitative PCR on first-strand cDNA we show that expression of functional antisense genes lead to reduced levels of uidA mRNA. This suggests that the mechanism of antisense RNA inhibition in protoplasts is similar to that in transgenic plants and that the protoplast system in combination with PCR can be used to preselect antisense fragments of any gene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021418
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  • 12
    Electronic Resource
    Electronic Resource
    Treatment of Agrobacterium or leaf disks with 5-azacytidine increases transgene expression in tobacco (1993)
    Springer
    Plant molecular biology 21 (1993), S. 429-435 
    Details
    ISSN: 1573-5028
    Keywords: azacytidine ; DNA methylation ; gene expression ; inactivation ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have studied the effect of the demethylating agent azacytidine (azaC) on expression of a β-glucuronidase (GUS) gene transferred to tobacco leaf disks by Agrobacterium-mediated transformation. In a system where no selection was performed, where shoot formation was partially repressed, and where Agrobacterium does not express the GUS gene, we were able to follow the early events of transient and stable expression. Two days after inoculation, 8% of the cells expressed GUS but this proportion rapidly decreased to near zero in the following week. Treatment of leaf disks with azaC just after transformation retarded this inactivation to some extent, while treatment of Agrobacterium prior to transformation increased the frequency of transient expression. Three weeks after inoculation the number of GUS-expressing cells increased 4- to 6-fold in the leaf disks treated with azaC and in the leaf disks transformed with azaC-treated bacteria, while the control remained low. These data suggest that DNA methylation is involved in transgene inactivation and that a large number of silent but potentially active transgenes become integrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028801
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  • 13
    Electronic Resource
    Electronic Resource
    Activity of a chimeric promoter with the doubled CaMV 35S enhancer element in protoplast-derived cells and transgenic plants in maize (1993)
    Springer
    Plant molecular biology 21 (1993), S. 415-428 
    Details
    ISSN: 1573-5028
    Keywords: Zea mays L. ; protoplast ; DNA uptake ; transformation ; β-glucuronidase ; promoter ; α-amylase gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A reproducible and efficient transformation system has been developed for maize that is based on direct DNA uptake into embryogenic protoplasts and regeneration of fertile plants from protoplast-derived transgenic callus tissues. Plasmid DNA, containing the β-glucuronidase (GUS) gene, under the control of the doubled enhancer element (the −208 to −46 bp upstream fragment) from CaMV 35S promoter, linked to the truncated (up to −389 bp from ATG) promoter of wheat, α-amylase gene was introduced into protoplasts from suspension culture of HE/89 genotype. The constructed transformation vectors carried either the neomycin phosphotransferase (NPTII) or phosphinothricin acetyltransferase (PAT) gene as selective marker. The applied DNA uptake protocol has resulted at least in 10–20 resistant calli, or GUS-expressing colonies after treatment of 106 protoplasts. Vital GUS staining of microcalli has made possible the shoot regeneration from the GUS-stained tissues. 80–90% of kanamycin or PPT resistant calli showed GUS activity, and transgenic plants were regenerated from more than 140 clones. Both Southern hybridization and PCR analysis showed the presence of introduced foreign genes in the genomic DNA of the transformants. The chimeric promoter, composed of a tissue specific monocot promoter, and the viral enhancer element specified similar expression pattern in maize plants, as it was determined by the full CaMV 35S promoter in dicot and other monocot plants. The highest GUS specific activity was found in older leaves with progressively less activity in young leaves, stem and root. Histochemical localization of GUS revealed promoter function in leaf epidermis, mesophyll and vascular bundles, in the cortex and vascular cylinder of the root. In roots, the meristematic tip region and vascular tissues stained intensively. Selected transformants were grown up to maturity, and second-generation seedlings with segregation for GUS activity were obtained after outcrossing. The GUS-expressing segregants carried also the NPTII gene as shown by Southern hybridization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028800
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  • 14
    Electronic Resource
    Electronic Resource
    Transient and stable expression ofgusA fusions with rice genes in rice, barley and perennial ryegrass (1993)
    Springer
    Plant molecular biology 22 (1993), S. 1101-1127 
    Details
    ISSN: 1573-5028
    Keywords: transformation ; promoters ; introns ; gene expression ; Oryza sativa ; Hordeum vulgare ; Lolium perenne
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcriptional and translational fusions were made between the reading frame coding for β-D-glucuronidase and sequences of either a constitutively expressed rice gene (GOS2) involved in initiation of translation or a light-inducible rice gene (GOS5). The transient expression of the fusions was studied via particle bombardment of seedling tissues of rice, perennial ryegrass and barley. Furthermore, the results of transient and stable expression were compared for cell suspensions of four rice varieties, one barley variety and one perennial ryegrass variety. TheGOS2-gusA fusions were active in all three monocots studied. Best results were obtained for a construct having both a transcriptional and a translational fusion as well as intron and exon sequences (PORCEHyg). The level of GUS activity was in the range of activities as obtained by the 35S CaMV promoter transcriptionally fused togusA. ThegusA fusion with the light-inducible gene (GOS5) was active in green seedling tissues of all monocots studied. Also a weak expression compared to theGOS2 constructs was found in stably transformed rice callus. ThegusA fusions with the mannopine synthase promoters 1′ and 2′ of the TR-DNA were transiently expressed at lower levels in cell suspensions than PORCEHyg. For stably transformed rice callus the expression of theGOS2-gusA fusion often decreased during prolonged subculture. This decrease in GUS activity and the various GUS-staining phenotypes of transgenic calli are explained by the presence of different cell types in the suspensions used and in the calli. It is presumed that the nature of the cells and their relative contribution in the calli change drastically upon further subculture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028980
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  • 15
    Electronic Resource
    Electronic Resource
    Transient and stable expression of gusA fusions with rice genes in rice, barley and perennial ryegrass (1993)
    Springer
    Plant molecular biology 23 (1993), S. 643-669 
    Details
    ISSN: 1573-5028
    Keywords: transformation ; promoters ; introns ; gene expression ; Oryza sativa ; Hordeum vulgare ; Lolium perenne
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcriptional and translational fusions were made between the reading frame coding for β-D-glucuronidase and sequences of either a constitutively expressed rice gene (GOS2) involved in initiation of translation or a light-inducible rice gene (GOS5). The transient expression of the fusions was studied via particle bombardment of seedling tissues of rice, perennial ryegrass and barley. Furthermore, the results of transient and stable expression were compared for cell suspensions of four rice varieties, one barley variety and one perennial ryegrass variety. The GOS2-gusA fusions were active in all three monocots studied. Best results were obtained for a construct having both a transcriptional and a translational fusion as well as intron and exon sequences (PORCEHyg). The level of GUS activity was in the range of activities as obtained by the 35S CaMV promoter transcriptionally fused to gusA. The gusA fusion with the light-inducible gene (GOS5) was active in green seedling tissues of all monocots studied. Also a weak expression compared to the GOS2 constructs was found in stably transformed rice callus. The gusA fusions with the mannopine synthase promoters 1′ and 2′ of the TR-DNA were transiently expressed at lower levels in cell suspensions than PORCEHyg. For stably transformed rice callus the expression of the GOS2-gusA fusion often decreased during prolonged subculture. This decrease in GUS activity and the various GUS-staining phenotypes of transgenic calli are explained by the presence of different cell types in the suspensions used and in the calli. It is presumed that the nature of the cells and their relative contribution in the calli change drastically upon further subculture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021522
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  • 16
    Electronic Resource
    Electronic Resource
    Use of bar as a selectable marker gene and for the production of herbicide-resistant rice plants from protoplasts (1993)
    Springer
    Plant molecular biology 21 (1993), S. 871-884 
    Details
    ISSN: 1573-5028
    Keywords: bar ; herbicide resistance ; phosphinothricin acetyltransferase ; rice ; selectable marker ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have used the bar gene in combination with the herbicide Basta to select transformed rice (Oryza sativa L. cv. Radon) protoplasts for the production of herbicide-resistant rice plants. Protoplasts, obtained from regenerable suspension cultures established from immature embryo callus, were transformed using PEG-mediated DNA uptake. Transformed calli could be selected 2–4 weeks after placing the protoplast-derived calli on medium containing the selective agent, phosphinothricin (PPT), the active component of Basta. Calli resistant to PPT were capable of regenerating plants. Phosphinothricin acetyltransferase (PAT) assays confirmed the expression of the bar gene in plants obtained from PPT-resistant calli. The only exceptions were two plants obtained from the same callus that had multiple copies of the bar gene integrated into their genomes. The transgenic status of the plants was varified by Southern blot analysis. In our system, where the transformation was done via the protoplast method, there were very few escapes. The efficiency of co-transformation with a reporter gene gusA, was 30%. The To plants of Radon were self-fertile. Both the bar and gusA genes were transmitted to progeny as confirmed by Southern analysis. Both genes were expressed in T1 and T2 progenies. Enzyme analyses on T1 progeny plants also showed a gene dose response reflecting their homozygous and heterozygous status. The leaves of To plants and that of the progeny having the bar gene were resistant to application of Basta. Thus, the bar gene has proven to be a useful selectable and screenable marker for the transformation of rice plants and for the production of herbicide-resistant plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027118
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  • 17
    Electronic Resource
    Electronic Resource
    Construction of a Synechocystic PCC6803 mutant suitable for the study of variant hexadecameric ribulose bisphosphate carboxylase/oxygenase enzymes (1993)
    Springer
    Plant molecular biology 23 (1993), S. 465-476 
    Details
    ISSN: 1573-5028
    Keywords: carboxysomes ; cyanobacteria ; rbc genes ; Rubisco ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cyanobacterium Synechocystis PCC6803 was chosen as a target organism for construction of a suitable photosynthetic host to enable selection of variant plant-like ribulose bisphosphate carboxylase/oxygenase (Rubisco) enzymes. The DNA region containing the operon encoding Rubisco (rbc) was cloned, sequenced and used for the construction of a transformation vector bearing flanking sequences to the rbc genes. This vector was utilized for the construction of a cyanobacterial rbc null mutant in which the entire sequence comprising both rbc genes, was replaced by the Rhodospirillum rubrum rbcL gene linked to a chloramphenicol resistance gene. Chloramphenicol-resistant colonies, Syn6803†rbc, were detected within 8 days when grown under 5% CO2 in air. These transformants were unable to grow in air (0.03% CO2). Analysis of their genome and Rubisco protein confirmed the site of the mutation at the rbc locus, and indicated that the mutation had segregated throughout all of the chromosome copies, consequently producing only the bacterial type of the enzyme. In addition, no carboxysome structures could be detected in the new mutant. Successful restoration of the wild-type rbc locus, using vectors bearing the rbc operon flanked by additional sequences at both termini, could only be achieved upon incubating the transformed cells under 5% CO2 in air prior to their transferring to air. The yield of restored transformants was proportionally related to the length of those sequences flanking the rbc operon which participate in the homologous recombination. The Syn6803Δrbc mutant is amenable for the introduction of in vitro mutagenized rbc genes into the rbc locus, aiming at the genetic modification of the hexadecameric type Rubisco.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019295
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  • 18
    Electronic Resource
    Electronic Resource
    Localization of light-inducible and tissue-specific regions of the spinach ribulose bisphosphate carboxylase/oxygenase (rubisco) activase promoter in transgenic tobacco plants (1993)
    Springer
    Plant molecular biology 23 (1993), S. 1129-1138 
    Details
    ISSN: 1573-5028
    Keywords: cis elements ; light regulation ; Rca promoter ; rubisco activase ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Deletions in the spinach rubisco activase (Rca) promoter in transgenic tobacco were analyzed to define the regions necessary for conferring light-inducible and tissue-specific expression. Transgenic plants were constructed with Bal 31 deletions of the Rca promoter fused to the coding region of the bacterial reporter gene β-glucuronidase (GUS). Analysis of the Rca deletion mutants localized the region conferring normal expression downstream from −294 relative to the Rca transcription start site. A second set of transgenic plants containing the cauliflower mosaic virus (CaMV) 35S enhancer fused to the 3′ end of the Rca/GUS constructs demonstrated the presence of a light-responsive element between −150 and −78 active in leaves. Regions 10 bp long within the light-responsive region, which included putative G box and GT elements, were removed by recombinant polymerase chain reaction. Deletion of the G box element resulted in a loss of gene expression in the leaves of transgenic tobacco, while deletion of the GT motif caused a 10–100-fold increase in expression in roots. However, site-directed mutagenesis of the GT motif resulted in expression patterns identical to the normal promoter. These experiments demonstrated that light-inducible and tissue-specific expression of the Rca promoter involves multiple cis elements proximal to the transcription start site, and that interactions between these elements are essential for regulating expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042347
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  • 19
    Electronic Resource
    Electronic Resource
    The GAPDH gene system of the red alga Chondrus crispus: promotor structures, intron/exon organization, genomic complexity and differential expression of genes (1993)
    Springer
    Plant molecular biology 23 (1993), S. 981-994 
    Details
    ISSN: 1573-5028
    Keywords: cis-acting elements ; intron conservation ; intron secondary structure ; pre-mRNA splicing ; CpG suppression ; protoplasts ; transcript levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Our previous phylogenetic analysis based on cDNA sequences of chloroplast and cytosolic glyceraldehyde-3-phosphate dehydrogenases (GAPDH; genes GapA and GapC, respectively) of the red alga Chondrus crispus suggested that rhodophytes and green plants are sister groups with respect to plastids and mitochondria and diverged at about the same time or somewhat later than animals and fungi. Here we characterize the genomic sequences of genes GapC and GapA of C. crispus with respect to promotor structures, intron/exon organization, genomic complexity, G+C content, CpG suppression and their transcript levels in gametophytes and protoplasts, respectively. To our knowledge this is the first report on nuclear protein genes of red algae. The GapC gene is G+C-rich, contains no introns and displays a number of classic sequence motifs within its promotor region, such as TATA, CAAT, GC boxes and several elements resembling the plant-specific G-box palindrome. The GapA gene has a moderate G+C content, a single CAAT box motif in its promotor region and a single intron of 115 bp near its 5′ end. This intron occupies a conserved position corresponding to that of intron 1 in the transit peptide region of chloroplast GAPDH genes (GapA and GapB) of higher plants. It has consensus sequences similar to those of yeast introns and folds into a conspicuous secondary structure of - 61.3 kJ. CpG profiles of genes GapC and GapA and their flanking sequences show no significant CpG depletion suggesting that these genomic sequences are not methylated. Genomic Southern blots hybridized with generic and gene specific probes indicate that both genes are encoded by single loci composed of multiple polymorphic alleles. Northern hybridizations demonstrate that both genes are expressed in gametophytes but not in protoplasts where appreciable amounts of transcripts can only be detected for GapC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021813
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  • 20
    Electronic Resource
    Electronic Resource
    Improvement of protoplast culture protocols for Beta vulgaris L. (sugar beet) (1993)
    Springer
    Plant cell reports 12 (1993), S. 339-342 
    Details
    ISSN: 1432-203X
    Keywords: Alginate embedding ; Beta vulgaris ; feeders ; protoplasts ; regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effects of NaCl, feeder cells and the embedding of protoplasts in calcium alginate have been investigated in an attempt to improve culture conditions of recalcitrant sugar beet (Beta vulgaris L.) mesophyll protoplasts. While the use of NaCl in all instances proved detrimental to protoplast development, the other two treatments had clear beneficial effects. Minimum plating densities, necessary to sustain cell division, could be reduced to 〈5% (〈4000 protoplasts / ml) of the control levels and plating efficiencies could be significantly enhanced by approx. 10 fold. Plants could still be regenerated from soft calli derived from mesophyll protoplasts cultured under the modified conditions at a frequency of 20–30 %. In particular, the use of alginate is considered of potentially great importance for the further application of beet protoplasts for other aims e.g. asymmetric hybridization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237431
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  • 21
    Electronic Resource
    Electronic Resource
    Investigations of boron uptake at the cellular level (1993)
    Springer
    Plant and soil 155-156 (1993), S. 143-146 
    Details
    ISSN: 1573-5036
    Keywords: barley ; cell wall ; Hordeum vulgare ; pollen selection ; protoplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The nature of expression of the tolerance of barley to high levels of B at the cellular level was investigated with a view to identifying ways by which this level of expression might be exploited in a breeding programme. Using protoplasts derived from leaf tissue, it was found that genetic differences between B tolerant and intolerant barleys were not expressed in the absence of cell walls. Barley genotypes differing in their tolerance to B were subjected to high levels of B in the growth medium from pollen formation onwards. The genetic distribution of segregating populations in the next generation was not changed for tolerance to high B. Results also suggested that genetic tolerance to B is expressed by pollen in vitro.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00025004
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  • 22
    Electronic Resource
    Electronic Resource
    Plant regeneration from protoplasts isolated from cell suspension cultures of the wild tomato, Lycopersicon chilense Dun. (1993)
    Springer
    Plant cell, tissue and organ culture 32 (1993), S. 311-317 
    Details
    ISSN: 1573-5044
    Keywords: cell suspension ; Lycopersicon chilense ; plant regeneration ; protoplasts ; wild tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A protocol has been established for rapid, high frequency plant regeneration from protoplasts of the wild tomato species Lycopersicon chilense Dun. Cell suspension cultures were obtained from calli initiated from seedling stem explants. Protoplasts were isolated from cell suspensions by an overnight one-step enzyme digestion, purified by washing in salts solution and cultured in liquid medium. Dilution of liquid medium every 3 days, with medium containing low levels of growth regulators and sucrose, was critical for sustained colony formation. Up to 70% of protoplast-derived calli regenerated shoots when cultured on agar-solidified medium with Murashige & Skoog (1962) salts and vitamins, 2.0 mg l-1 zeatin and 0.1 mg l-1 indole acetic acid for 21 days, followed by transfer to the same medium lacking indole acetic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042294
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  • 23
    Electronic Resource
    Electronic Resource
    A study of some factors affectingAgrobacterium transformation and plant regeneration ofDendranthema grandiflora Tzvelev (syn.Chrysanthemum morifolium Ramat.) (1993)
    Springer
    Plant cell, tissue and organ culture 33 (1993), S. 171-180 
    Details
    ISSN: 1573-5044
    Keywords: Agrobacterium ; Dendranthema grandiflora ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In an attempt to develop a system for producing transformed plants from explants ofDendranthema grandiflora, the susceptibility of the cultivar Super White to various wild-type strains ofAgrobacterium tumefaciens andA. rhizogenes was investigated. Tumour formation was not a reliable indicator of the ability of a related disarmed strain to mediate transformation. Following inoculation of explants with disarmedAgrobacterium strains, a number of shoots developed on selective media. However, none of these shoots were transformed. By co-cultivating stem internode explants with a mixed inoculum of wild-type and disarmed strains, it was possible to obtain a callus stably transformed withAgrobacterium carrying a disarmed T-DNA. Histological analysis of explants revealed that shoot regeneration initially occurred from the cells of the epidermis and subsequently from the cortex. However, the cells which were susceptible to T-DNA transfer were confined to the vascular tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01983231
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  • 24
    Electronic Resource
    Electronic Resource
    Culturing embryogenic protoplasts of ‘Hamlin’ sweet orange in calcium alginate beads (1993)
    Springer
    Plant cell, tissue and organ culture 34 (1993), S. 19-25 
    Details
    ISSN: 1573-5044
    Keywords: Ca-alginate ; citrus ; plating efficiency ; protoplasts ; somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protoplasts were enzymatically isolated from log phase embryogenic sweet orange [Citrus sinensis (L.) Osbeck cv. Hamlin] suspension cultures, embedded in 3-mm diameter Ca-alginate beads, and cultured in a growth cabinet (15–20 μ mol m-2 s-1, 4-h photoperiod, 27°C). Plating efficiency exceeded 90% for Ca-alginate embedded protoplasts vs. 30% for protoplasts cultured in a liquid medium. Embryoids formed from protoplasts were recovered after 20 days by dissolving the Ca-alginate matrix with a calcium sequestrant. Embryoids readily formed shoots that were rooted on MS+0.01 μM NAA+5% sucrose. Potential applications are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048459
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  • 25
    Electronic Resource
    Electronic Resource
    The role of endogenous auxin in root initiation (1993)
    Springer
    Plant growth regulation 13 (1993), S. 77-84 
    Details
    ISSN: 1573-5087
    Keywords: Agrobacterium rhizogenes ; auxin ; indole-3-acetic acid (IAA) ; root initiation ; sensitivity ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper is the second part of a review which considers evidence for the involvement of auxin in root initiation. Part II examines the research being carried out with transformed plant tissues. Agrobacterium rhizogenes causes abundant root initiation at the site of inoculation. Ri plasmid T-DNA contains several genes which encode enzymes involved in the biosynthesis and metabolism of indole-3-acetic acid. Transfer of various fragments of the Ri plasmid has also been reported to confer increased sensitivity to auxin upon plant cells. Controlled expression of these genes in the plant genome potentially offer an insight for developmental plant physiologists into the role of plant growth substances in the process of root initiation. The importance of absolute levels of IAA in the stimulation of root initiation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00207595
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  • 26
    Electronic Resource
    Electronic Resource
    Regeneration of whole plants from Gracilaria asiatica Chang et Xia protoplasts (Gracilariaceae, Rhodophyta) (1993)
    Springer
    Hydrobiologia 260-261 (1993), S. 429-436 
    Details
    ISSN: 1573-5117
    Keywords: Gracilaria ; protoplasts ; callus-like ; regeneration ; plant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A large number of viable protoplasts were produced by enzymatic digestion of Gracilaria asiatica vegetative tissue. The protoplasts underwent initial division after 5–7 d in culture and developed into callus-like cell-masses. Many filaments grew from the periphery of these cell-masses and disappeared after about one month in culture. Simultaneously, the central part of the callus-like cell-masses thickened and its color deepened. The first buds appeared from the center of the cell-masses and developed into whole plants after three months in aerated culture. Many new buds formed around the first plant and more than 20 plants grew per callus-like cell-masses in less than four months. Filaments taken from callus-like cell-masses developed into young plants after about 20 d of culture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00049052
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  • 27
    Electronic Resource
    Electronic Resource
    Microtubule organization in the apical cell of Sphacelaria (Phaeophyceae) and its related protoplast (1993)
    Springer
    Hydrobiologia 260-261 (1993), S. 167-172 
    Details
    ISSN: 1573-5117
    Keywords: Phaeophyceae ; protoplasts ; apical cells ; immunofluorescence ; microtubules ; cell cycle ; polarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth of the filamentous brown alga Sphacelaria depends on a large, strongly polarized, apical cell. The protoplast derived from this cell can be distinguished in a heterogeneous suspension by cytological markers, so it is possible to study development of the cytoskeleton during protoplast isolation and the first steps of regeneration. In the initial cell, microtubules show an asymmetric distribution along the axis; they are mainly located at the distal part around the physodes. After protoplast isolation, this polarity initially seems to be maintained; subsequently, the microtubules radiate from the two centrioles and spread out to the plasmalemma. This experimental model is suitable for investigating the development of the polarity of the initial cell, and the sequence of the first morphogenetic events leading to protoplast regeneration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00049016
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  • 28
    Electronic Resource
    Electronic Resource
    Protoplasts of Gelidium robustum (Rhodophyta) (1993)
    Springer
    Hydrobiologia 260-261 (1993), S. 421-427 
    Details
    ISSN: 1573-5117
    Keywords: protoplasts ; Gelidium robustum ; agarophyte ; Rhodophyta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Viable protoplasts were isolated from apices of the agarophyte Gelidium robustum (Gardn.) Hollenb. & Abb. using a combination of commercial cell-wall degrading enzymes and extracellular wall-degrading enzymes isolated from a marine bacterium. The protoplasts were approximately 8–15 µm in diameter, liberated mainly from the surface cell layers and from cells at the distal ends of medullary filaments. The bacterial enzyme alone was not sufficient to liberate significant numbers of protoplasts. Maximum yield was 9 × 105 protoplasts/g tissue (wet wt.). Optimum osmolality occurred between 1750–1950 mOs kg−1; yield and viability were severely diminished at osmolalities less than 1350 mOs kg−1. Viability, as determined by flurorescein diacetate staining and Evans Blue exclusion 1 hr after removal from the enzyme solution, was approximately 80–95%. Roughly 80% of the cells did not show Calcofluor fluorescence, while 40% stained positively for the presence of sulfated polysaccharides. Cell wall regeneration was observed with inconsistent reproducibility, and no cell division was observed when the protoplasts were placed in culture medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00049051
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  • 29
    Electronic Resource
    Electronic Resource
    Genetic engineering of grain and pasture legumes for improved nutritive value (1993)
    Springer
    Genetica 90 (1993), S. 181-200 
    Details
    ISSN: 1573-6857
    Keywords: plant ; genetic engineering ; nutritive value ; agrobacterium ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This review describes work aimed at the improvement of the nutritive value of grain and forage legumes using gene transfer techniques. Two traits which are amenable to manipulation by genetic engineering have been identified. These are plant protein quality and lignin content. In order to increase the quality of protein provided by the legume grains peas and lupins, we are attempting to introduce into these species chimeric genes encoding a sunflower seed protein rich in the sulphur-containing amino acids methionine and cysteine. These genes are designed to be expressed only in developing seeds of transgenic host plants. Chimeric genes incorporating a similar protein-coding region, but different transcriptional controls, are being introduced into the forage legumes lucerne and subterranean clover. In this case the genes are highly expressed in the leaves of transformed plants, and modifications have been made to the sunflower seed protein-coding sequences in order to increase the stability of the resultant protein in leaf tissue. Another approach to increasing plant nutritive value is represented by attempts to reduce the content of indigestible lignin in lucerne.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01435039
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  • 30
    Electronic Resource
    Electronic Resource
    Restoring adventitious shoot formation on chrysanthemum leaf explants following cocultivation with Agrobacterium tumefaciens (1993)
    Springer
    Plant cell, tissue and organ culture 32 (1993), S. 263-270 
    Details
    ISSN: 1573-5044
    Keywords: Dendranthema grandiflora ; preculture ; regeneration ; transformation ; β-glucuronidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Explants from leaves of in vitro-grown chrysanthemum (Dendranthema grandiflora Tzvel.) cultivars regenerated adventitious shoots without an intermediate callus phase. Puncturing explants with a brush increased regenerations, but in combination with cocultivation with Agrobacterium tumefaciens it had an adverse effect on shoot formation. The negative effect of brushing and cocultivation could be overcome by preculturing explants for 8 days. Preculture altered the location of transformed sites but did not inhibit transformation. Regeneration following cocultivation with Agrobacterium is also encouraged if alternative regeneration protocols are used that do not require brushing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042287
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  • 31
    Electronic Resource
    Electronic Resource
    Effect of digitonin on membrane-bound and chitosomal chitin synthetase activity in protoplasts from yeast cells ofCandida albicans (1993)
    Springer
    Antonie van Leeuwenhoek 64 (1993), S. 67-74 
    Details
    ISSN: 1572-9699
    Keywords: Candida albicans ; chitin synthetase ; digitonin ; proenzyme activation ; protoplasts ; solubilization ; zymogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of digitonin on chitin synthetase present in membrane (MMF) and cytoplasmic fractions (chitosomes) (CF) fromC. albicans yeast protoplasts has been determined. The zymogen is preferentially, but not exclusively, solubilized by digitonin from MMF. Centrifugation of distinct solubilized preparations, containing either zymogen,in vivo active enzyme and/or trypsin activated enzyme, on linear sucrose gradients suggests that both zymogen and trypsin activated enzyme sediment slightly slower than the active enzyme, pointing out differences between the activation processesin vivo andin vitro or, alternatively, that both enzyme activities (activein vivo and zymogenic) correspond to different gene products. The detection of a zymogenic activity under certain conditions (0.5 mg ml−1 of digitonin and 64 µg ml−1 of trypsin) also suggests the existence of more than one pool of zymogenic enzyme in the MMF. Digitonin sensitizes the chitosomal (CF) proenzyme to trypsin: activation is enhanced by low digitonin concentrations in the presence of 8 µg ml−1 of protease, whereas activity strongly decreases in the presence of 64 µg ml−1 of trypsin. Digitonin does not produce zymogen activationper se in absence of exogenous protease. Furthermore, chitosome structure is modified into particles with low buoyant densities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00870923
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  • 32
    Electronic Resource
    Electronic Resource
    The cell biology of plant transformation: Current state, problems, prospects and the implications for the plant breeding (1993)
    Springer
    Euphytica 71 (1993), S. 1-14 
    Details
    ISSN: 1573-5060
    Keywords: Agrobacterium tumefaciens ; biolistics ; co-suppression ; co-transformation ; electroporation ; epistasis ; gene silencing ; somaclonal variation ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The DNA delivery systems which are routinely used to introduce genes into crop plants are Agrobacterium tumefaciens, electroporation and particle bombardment. The differences and similarities between these different transformation techniques are outlined. The influence of the cell biological approach, and more specifically the impact of the state of the plant cell at the moment of transformation, on the genotype and phenotype of the regenerated transgenic plant is analysed. In this respect phenomena such as position effects, gene silencing, co-suppression, epistasis, co-transformation and somaclonal variation are discussed. The relevance of these factors for plant breeders is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023461
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  • 33
    Electronic Resource
    Electronic Resource
    An efficient protoplast-to-plant system for the hybrid ornamental shrub,Weigela ×florida cv. Bristol Ruby (Caprifoliaceae) (1993)
    Springer
    Plant cell, tissue and organ culture 33 (1993), S. 315-320 
    Details
    ISSN: 1573-5044
    Keywords: protoplasts ; plant regeneration ; woody ornamentals ; Weigela
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Strategies were developed for the successful isolation of large numbers of highly viable protoplasts from the leaves, stems and roots of axenic plants of the hybrid ornamental shrubWeigela ×florida cv Bristol Ruby. Protoplasts, of all sources, were cultured on different media, leading to the establishment of sustained divisions, and coupled with the production of multi-celled (〉50 cells) colonies. However, those colonies derived from mesophyll protoplasts only were capable of a further proliferation to the callus stage. Upon transfer to a regeneration medium consisting of MS salts and organics plus a range of concentrations of NAA and BAP, such calli underwent caulogenesis, with optimum responses for a medium with 1.0 mg l−1 NAA and 1.0 mg l−1 BAP. The protoplast-derived shoots thus obtained were multiplied on MS medium with 0.1 mg l−1 IBA, 0.5 mg l−1 BAP and 0.1 mg l−1 GA3. Individual shoots were subsequently rooted on a half-strength MS medium plus 3.0 mg l−1 IBA, and complete protoplast-derived plants were finally transferred to the glasshouse for acclimatization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02319017
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  • 34
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    Electronic Resource
    Efficient plant regeneration from protoplasts of Arachis paraguariensis Chod. et Hassl. using a nurse culture method (1993)
    Springer
    Plant cell, tissue and organ culture 34 (1993), S. 83-90 
    Details
    ISSN: 1573-5044
    Keywords: Arachis species ; nurse culture ; plant regeneration ; protoplasts ; tissue culture ; wild peanut
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An efficient protocol has been developed for protoplast culture and plant regeneration from wild peanut (A. paraguariensis) using a nurse culture method. Protoplasts were isolated from suspension cultures initiated from leaf-derived callus, imbedded in agarose blocks and co-cultured with nurse cells of the same species. Up to 10% of the protoplasts divided and formed compact callus colonies. The protoplast plating efficiency was correlated with both the length of the nurse cell co-cultivation period and the protoplast plating density. The optimal nurse culture duration was 14 d. The optimal plating density was 2×104 protoplasts/ml plating medium. Multiple shoots (up to 10 shoots per colony) were readily regenerated from protoplast-derived callus after transfer of callus to semi-solid modified MS medium containing 0.5 mg l-1 NAA and 1 mg l-1 BA. Plantlets with normal leaflets were obtained by rooting shoots on porous rootcubes saturated with modified MS medium containing 1 mg l-1 NAA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048467
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  • 35
    Electronic Resource
    Electronic Resource
    Solvent effect on the inclusion of 2-acetylnaphthalene by 1,1-di(p-hydroxyphenyl)cyclohexane (1993)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 15 (1993), S. 27-36 
    Details
    ISSN: 1573-1111
    Keywords: Crystallization ; nucleation ; crystal growth ; polymorph ; molecular complex ; transformation ; solvent effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of the solvents acetone (AT), dimethylsulfoxide (DMSO) and methylcellosolve (MCS) on the inclusion of 2-acetylnaphthalene (2-AN) in the host, 1,1-di(p-hydroxyphenyl)cyclohexane (DHC) has been investigated. Each solvent molecule is included in DHC in a molar ratio of 1.0, when DHC is crystallized from the solvents. The evaporation rate of these solvents from the host lattice decreases in the order AT, MCS and DMSO. The order agrees well with the interaction strength between the host and solvent molecule, which was measured by DSC and IR. 2-AN cannot be included in the crystals by crystallization from MCS and DMSO solutions. However, in AT solution both AT and 2-AN are included competitively and the morphology of the crystals is different from that obtained in pure solution. The amount of 2-AN in the crystals increases continuously with its concentration in solution. This behavior indicates that AT is replaced by 2-AN and the solid solution of the molecular complex is formed. The solid solution is a metastable form and the solution-mediated tranformation to the stable form (which includes only AT) was observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00706471
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  • 36
    Electronic Resource
    Electronic Resource
    Stable transformation of peanut callus viaAgrobacterium-mediated DNA transfer (1993)
    Springer
    Transgenic research 2 (1993), S. 321-324 
    Details
    ISSN: 1573-9368
    Keywords: Peanut ; Arachis hypogaea ; transformation ; callus ; Agrobacterium tumefaciens ; peanut stripe virus coat protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transformed callus was produced from peanut (Arachis hypogaea L. cv. Okrun) hypocotyl explants after four days of co-cultivation withAgrobacterium tumefaciens strains EHA101, LBA4404 or ASE1 carrying the binary vector pKYLX71GUS on a defined medium followed by selection with kanamycin (200 mg l−1). Transformed calluses were cultured as independent cell lines potentially derived from a single transformation event. Stable integration and expression of foreign gene(s) in the callus was confirmed by Southern and western blot analyses and enzyme assays. A few cell lines showed a single insert of the foreign gene. Using the above protocol, transformed peanut callus expressing the peanut stripe virus coat protein gene was obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01976172
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  • 37
    Electronic Resource
    Electronic Resource
    Introduction of hygromycin resistance inLotus spp. throughAgrobacterium rhizogenes transformation (1993)
    Springer
    Transgenic research 2 (1993), S. 330-335 
    Details
    ISSN: 1573-9368
    Keywords: Lotus ; Agrobacterium rhizogenes ; transformation ; hygromycin resistance ; tannins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The speciesLotus corniculatus andL. tenuis were transformed with anAgrobacterium rhizogenes binary vector, conferring resistance to the antibiotic hygromycin. Transgenic plants recovered from both species were tested for the ability of leaf-derived calluses to grow in a hygromycin-supplemented medium. Molecular analysis showed the integration of the Ri T-DNA and of the gene for hygromycin resistance, with a high frequency of co-transformation. Progeny analysis of the hygromycin resistance indicated this to be a single Mendelian trait in test plants. The transformed plants will be utilized in somatic hybridization experiments with lucerne for producing non-bloating genotypes with condensed tannins in leaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01976174
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  • 38
    Electronic Resource
    Electronic Resource
    Interaction of the neu/p185 and EGF receptor tyrosine kinases: Implications for cellular transformation and tumor therapy (1993)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 53 (1993), S. 61-73 
    Details
    ISSN: 0730-2312
    Keywords: neu/p185 protein ; c-erbB-2 ; epidermal growth factor receptor ; transformation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Growth factor receptors such as the epidermal growth factor receptor (EGFR) and the p185c-neu protein serve vital roles in the transduction of differentiation, developmental, or mitogenic signaling within normal cells. Two methods of analysis suggest that the inappropriately high expression of either protein tyrosine kinase promotes malignant transformation. First, data from in vitro experiments indicate that overexpression of either EGFR or p185c-neu (or the human homolog c-erbB-2) transforms cell-lines. Second, analysis of primary tumors and tumor cell-lines derived from many epithelial tissues (breast, stomach, ovary, and pancreas) show growth factor receptor gene amplification and elevated protein levels. The physical and functional interaction of p185c-neu and EGFR leads to the formation of a highly active, heterodimeric tyrosine kinase complex which synergistically activates cellular transformation. Anti-receptor antibodies have shown potential utility for the down modulation of these cell-surface proteins and suppression of the malignant phenotype. Design of organic antibody “mimetics” based on the structure of antireceptor antibodies may provide useful therapies and biological reagents to affect growth factor receptor function.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240530108
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