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  • 1
    Electronic Resource
    Electronic Resource
    Behaviour of chromosomes in anaphase cells in embryogenic callus cultures of maize (Zea mays L.) (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 982-990 
    Details
    ISSN: 1432-2242
    Keywords: Zea mays L. ; Tissue culture ; Aberrations in chromosome structure ; Heterochromatic knobs ; Chromosome behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mitotic anaphase cells of highly friable and embryogenic calluses which had been induced from immature embryos of two inbred lines of maize that have contrasting levels of heterochromatic knobs were analysed for the presence of abnormalities 3, 6, 9 and 12 months after the initiation of culture. A total of 500 typical anaphases was scored at each time point, and various aberrations, such as delay in the separation of sister chromatides, chromosome bridges (single, double and multiple) and chromosome fragments, were revealed to occur extensively in the cultures of both genotypes. Preparations after C-banding revealed that primary breakages often occurred inside knobs or at junction regions between the euchromatin and the heterochromatin of the knobs. Figures characterized by the delayed separation of sister chromatids, which originated preferentially at the knob level and was considered to be an initial event in the development of breakages, were observed at constant frequencies throughout the experiment. Increasing numbers of aberrant cells were detected with time, mainly due to the accumulation of cells with chromosome bridges and fragments. Several mitotic figures suggested the occurrence of breakagefusion-bridge cycles that were initiated by broken chromosomes. The overall frequencies of aberrant cells were similar for both genotypes, despite the differences in knob composition. However, callus cultures induced from the genotype having the higher level of knobs had more aberrant cells with abnormalities that involved several chromosomes, such as multiple bridges and multiple fragments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224038
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The physical map of the chloroplast DNA from Asparagus officinalis L. (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 10-14 
    Details
    ISSN: 1432-2242
    Keywords: Chloroplast DNA (ctDNA) ; Physical map ; Garden asparagus ; Asparagus officinalis L. ; Chloroplast genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genus Asparagus consists of 100–300 species of both dioecious and hermaphrodite plants. Since there are diploid, tetraploid, and hexaploid plants in this genus, RFLP (restriction fragment length polymorphism) analysis of chloroplast DNA (ctDNA) is suitable for examining the phylogenetic relationships. We have constructed a physical map of the ctDNA of garden asparagus (A. officinalis L. cv ‘Mary Washington 500 W’) using five restriction endonucleases, namely, BamHI, PstI, SalI, HindIII, and XhoI. Asparagus ctDNA was digested with restriction enzymes and cloned into plasmid and λ phage vectors, and a clone bank was constructed that covered 70% of the genome. A physical map was constructed by Southern hybridization of total DNA from asparagus with homologous and heterologous probes. The asparagus ctDNA was about 155 kb long and it contained two inverted repeats (23kb each) separated by a large single-copy region (90kb) and a small single-copy region (19kb). Fifteen genes, encoding photosynthesis-related proteins, rDNAs, and tRNAs, were localized on the physical map of asparagus ctDNA. Comparing the length and the gene order of asparagus ctDNA with that of other plants, we found that asparagus ctDNA was similar to tobacco ctDNA but different from rice ctDNA. The restriction patterns of the ctDNAs from several varieties of A. officinalis and three species of Asparagus were analyzed. The restriction patterns of the varieties of A. officinalis were very similar, but polymorphisms were detected among the three species of Asparagus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222945
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Behaviour of chromosomes in anaphase cells in embryogenic callus cultures of maize (Zea mays L.) (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 982-990 
    Details
    ISSN: 1432-2242
    Keywords: Key words Zea mays L. ; Tissue culture ; Aberrations in chromosome structure ; Heterochromatic knobs ; Chromosome behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mitotic anaphase cells of highly friable and embryogenic calluses which had been induced from immature embryos of two inbred lines of maize that have contrasting levels of heterochromatic knobs were analysed for the presence of abnormalities 3, 6, 9 and 12 months after the initiation of culture. A total of 500 typical anaphases was scored at each time point, and various aberrations, such as delay in the separation of sister chromatides, chromosome bridges (single, double and multiple) and chromosome fragments, were revealed to occur extensively in the cultures of both genotypes. Preparations after C-banding revealed that primary breakages often occurred inside knobs or at junction regions between the euchromatin and the heterochromatin of the knobs. Figures characterized by the delayed separation of sister chromatids, which originated preferentially at the knob level and was considered to be an initial event in the development of breakages, were observed at constant frequencies throughout the experiment. Increasing numbers of aberrant cells were detected with time, mainly due to the accumulation of cells with chromosome bridges and fragments. Several mitotic figures suggested the occurrence of breakage-fusion-bridge cycles that were initiated by broken chromosomes. The overall frequencies of aberrant cells were similar for both genotypes, despite the differences in knob composition. However, callus cultures induced from the genotype having the higher level of knobs had more aberrant cells with abnormalities that involved several chromosomes, such as multiple bridges and multiple fragments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050219
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The structure of the chloroplast genome in members of the genus Asparagus (1997)
    Springer
    Theoretical and applied genetics 95 (1997), S. 1196-1202 
    Details
    ISSN: 1432-2242
    Keywords: Key words Asparagus ; Chloroplast DNA (ctDNA) ; Deletion ; Direct repeat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In a previous study we constructed a physical map of the chloroplast DNA (ctDNA) of garden asparagus (Asparagus officinalis L. cv ‘Mary Washington 500W’; Lee et al. 1996). In the present study we have constructed and compared HindIII and XhoI restriction maps of the ctDNAs of eight species of Asparagus: namely, A. officinalis, A. schoberioides, A. cochinchinensis, A. plumosus, A. falcatus, A. sprengeri, A. virgatus and A. asparagoides. The ctDNA of A. officinalis has 32 and 23 sites that are recognized by HindIII and XhoI, respectively. Taking the physical map of the ctDNA of A. officinalis as a standard, we found that the ctDNAs of A. falcatus, A. sprengeri, and A. asparagoides each had one additional HindIII site and lacked one XhoI site. We also detected two relatively large deletions of nucleotides in the ctDNA from A. cochinchinensis by sequencing analysis. Both of these deletions were located in a non-coding region between the ndhC and trnV genes and were 95 bp and 347 bp in length, respectively. The regions around the deletions exhibited strong homology, and short direct-repeat sequences were detected at the borders of the deletions, an indication that these deletions were the result of intramolecular recombination mediated by the direct repeats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050681
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    Paper (German National Licenses)
    Fulltext
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