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  • 1
    Electronic Resource
    Electronic Resource
    Genomic organization and phylogenetic relationships in the genus Dasypyrum analysed by Southern and in situ hybridization of total genomic and cloned DNA probes (1997)
    Springer
    Chromosoma 106 (1997), S. 53-61 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Molecular cytogenetic methods have been used to study the controversial phylogenetic relationships between the species Dasypyrum villosum (L.) Candargy (2n=2x=14) and D. breviaristatum (Lindb. f.) Frederiksen (2n=4x=28). Using total genomic DNA from the two species as probes for in situ hybridization to chromosomes, we found that the pericentromeric regions of the chromosome arms of both species are similar, while distal regions show substantial differences. Two dispersed repetitive DNA sequences were isolated: pDbKB45 is distributed along the chromosomes but amplified in the subtelomeric regions of D. breviaristatum chromosomes, while pDbKB49, in both species, is less amplified in terminal regions. Size-separated restriction enzyme digests of DNA showed many repetitive fragments, but few in common between the two species. After probing Southern transfers with D. breviaristatum genomic DNA, all lanes showed similar hybridization patterns although one extra small band was evident in the D. breviaristatum lanes. In contrast, probing with D. villosum DNA showed very substantial differences between the two species. Genomic in situ hybridization to meiotic metaphases from an interspecific hybrid showed seven bivalents of D. breviaristatum origin and seven univalents from D. villosum. We also analysed the physical organization of 5S rDNA, 18S-25S rDNA and a tandemly repeated sequence from rye. Our data support an autotetraploid origin for D. breviaristatum, but its genome and that of D. villosum show extensive differences, so the tetraploid is unlikely to be directly derived from D. villosum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004120050224
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  • 2
    Electronic Resource
    Electronic Resource
    Parental genomes are separated throughout the cell cycle in a plant hybrid (1991)
    Springer
    Chromosoma 101 (1991), S. 206-213 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The positions of the genomes originating from each parent were analysed in root-tip nuclei of the mature, sexual F1 hybrid plant Hordeum vulgare (barley) x Secale africanum (a wild rye). The two genomes of the hybrid were identified in both spread and sectioned material by non-radioactive DNA:DNA in situ hybridization using labelled total genomic DNA from one parent as a proble and unlabelled total genomic DNA from the other parent to block non-specific hybridization. Complete three-dimensional reconstructions of sets of labelled sections enabled detailed analysis of the position of the genomes at interphase. The parental genomes lay in various non-intermixed configurations, including lateral and concentric arrangements. On spread preparations, the two parental genomes were found to be spatially separated throughout the cell cycle; the genome originating from H. vulgare tended to be located more centrally than that from S. africanum. This results show that the nucleus is spatially organized above the level of the DNA and chromosome at the genome level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00365152
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  • 3
    Electronic Resource
    Electronic Resource
    Chromosome arrangements in human fibroblasts at mitosis (1991)
    Springer
    Human genetics 〈Berlin〉 88 (1991), S. 27-33 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The positions of the centromeres of all 46 human chromosomes were analysed in three dimensional reconstructions of electron micrographs of 10 serially sectioned unpretreated human male fibroblast cells. The reconstructions show that the spatial positioning of the chromosomes during division is not random. The centromeres were arranged on a metaphase plate that was ellipsoidal and that tended to be flat. The distance of centromeres from the centre of the mitotic figure was correlated with chromosome size; small chromosomes tended to be central in all the metaphases. Large chromosomes were more peripheral, especially in cells that were more advanced in mitosis. Thus, there is a tendency for larger chromosomes to move outwards as metaphase advances. In many cells, the A group centromeres were overdispersed, whereas G group centromeres tended to be clustered. The acrocentric chromosomes (D and G groups) also tended to be clustered when analysed together, probably reflecting associations in nucleoli at the previous interphase. The results show that chromosome disposition is non-random and that it changes during division.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00204924
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  • 4
    Electronic Resource
    Electronic Resource
    The spatial localization of homologous chromosomes in human fibroblasts at mitosis (1994)
    Springer
    Human genetics 〈Berlin〉 93 (1994), S. 275-280 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Chromosomes from ten human male fibroblast metaphases were completely reconstructed from electron micrographs of serially sectioned material. Chromosome centromere positions were determined by finding the three-dimensional coordinates of the centromere midpoint. The data set showed the identity of nine chromosome types (chromosomes 1, 2, 3, 6, 9, 16, 17, 18 and the Y chromosome) preserved as they are positioned in vivo. The results indicate that there is (1) no significant association of the homologous chromosomes examined, (2) a significant tendency for a central location of the Y chromosome and of chromosome 18, (3) a significant tendency for a peripheral location of chromosome 6, (4) no significant tendency for homologous chromosomes to reorganize as metaphase advances and (5) no significant differential condensation across the metaphase plate. Therefore, the only organization pattern observed for the centromeres of the homologous chromosomes studied is some sorting by size across the metaphase plate. These results may be typical of dividing cell types. Different chromosome arrangements are found in some non-dividing cell types (e.g. mammalian brain cells). The different distributions of chromosomes in different cell types can be considered as forms of “nuclear differentiation”. It is postulated that nuclear differentiation may be related to cell differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212022
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  • 5
    Electronic Resource
    Electronic Resource
    Motility in ungerminated grass pollen: association of myosin with polysaccharide-containing wall-precursor bodies (P-particles) (1997)
    Springer
    Sexual plant reproduction 10 (1997), S. 65-66 
    Details
    ISSN: 1432-2145
    Keywords: Key words Triticum aestivum ; Pollen vegetative cell ; Intracellular motility ; P-particles ; Myosin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Grass pollens lack a dormancy period, remaining in a partly hydrated state at maturation with the contents of the vegetative cell continuing in active motion thereafter. The polysaccharide-containing wall-precursor bodies, derived mainly from previous dictyosome activity (P-particles), move randomly throughout much of the vegetative cell, but at the apertural pole of the grain many follow tracks related to actin fibrils focused on the single aperture. Isolated P-particles are shown by immunofluorescence localization using an antimyosin antibody to be associated individually with myosin. This, together with the fact that movement in the vegetative cell is arrested reversibly by cytochalasins, indicates that their motility is actomyosin based.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050068
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  • 6
    Electronic Resource
    Electronic Resource
    The absence of the somatic association of centromeres of homologous chromosomes in grass mitotic metaphases (1988)
    Springer
    Chromosoma 96 (1988), S. 119-131 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Root-tip metaphases from Hordeum vulgare (19 cells), H. marinum (11 cells), Aegilops umbellulata (10 cells) and Zea mays (10 cells) were completely reconstructed from electron micrographs of serially sectioned nuclei. The identity of each chromosome was found by measuring the volumes of its two arms and the presence or absence of a secondary constriction at the nucleolar organising region. With the position of the centromere in three dimensions, these data were used to analyse the relative positions of homologous and heterologous centromeres. In 31 out of the 50 cells analysed, homologues were on average further apart than heterologues. Except for two nucleolar organising chromosomes, there was no evidence of any tendency for the distances between different homologue types to be differently distributed from distances between heterologues. Average distances between homologues of the single nucleolar organising chromosome (linkage group 6) of Zea (2n = 20) were lower than the average for heterologues and the interhomologue distances were distributed significantly differently from the separation distances of chromosome 6 to other chromosomes. Presumably this association occurred because of nucleolar fusion in the previous interphase. Homologues of one of the two nucleolar organising chromosomes of A. umbellulata were also distributed significantly differently from heterologues, with a tendency for homologues to lie farther apart than the average heterologous pair. These results do not support previous work using squashed and spread metaphase preparations (some including abnormal, marked chromosomes) for these species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331044
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  • 7
    Electronic Resource
    Electronic Resource
    The volumes and morphology of human chromosomes in mitotic reconstructions (1989)
    Springer
    Human genetics 〈Berlin〉 84 (1989), S. 27-34 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ten unpretreated normal human male fibroblast cells in mitosis were completely reconstructed from micrographs of between 82 and 119 consecutive serial sections. All 46 chromosomes and their centromeres could be reconstructed in every cell. Measurements of chromosome volumes and centromere indices are presented. The data enabled allocation of all chromosomes to their groups (A to G), and chromosomes 1, 2, 3, 6, 9, 16, 17, 18 and Y were individually identified. Comparisons with published karyotypes showed that volume measurements correlated well with measurements of DNA content and chromosome length. Centromere indices also showed good correlation, but the acrocentric chromosomes were more unequally armed than found by length measurement. Secondary constrictions at the nucleolar organising region were visible on about a third of the acrocentric chromosomes. One chromosome of the C group, number 9, had a diffuse subcentromeric region (DSR) on the long arm, at the position of the constitutive heterochromatin and (in meiotic cells) the paramere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00210666
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  • 8
    Electronic Resource
    Electronic Resource
    The contribution of short repeats of low sequence complexity to large conifer genomes (2000)
    Springer
    Theoretical and applied genetics 101 (2000), S. 7-14 
    Details
    ISSN: 1432-2242
    Keywords: Key words Pinus ; Gymnosperms ; Simple sequence repeats ; Microsatellites ; Minisatellites ; Telomere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The abundance and genomic organization of six simple sequence repeats, consisting of di-, tri-, and tetranucleotide sequence motifs, and a minisatellite repeat have been analyzed in different gymnosperms by Southern hybridization. Within the gymnosperm genomes investigated, the abundance and genomic organization of micro- and minisatellite repeats largely follows taxonomic groupings. We found that only particular simple sequence repeat motifs are amplified in gymnosperm genomes, while others such as (CAC)5 and (GACA)4 are present in only low copy numbers. The variation in abundance of simple sequence motifs reflects a similar situation to that found in angiosperms. Species of the two- and three-needle pine section Pinus are relatively conserved and can be distinguished from Pinus strobus which belongs to the five-needle pine section Strobus. The hybridization pattern of Picea species, bald cypress and gingko were different from the patterns detected in the Pinus species. Furthermore, sequences with homology to the plant telomeric repeat (TTTAGGG)n have been analyzed in the same set of gymnosperms. Telomere-like repeats are highly amplified within two- and three- needle pine genomes, such as slash pine (Pinus elliottii Engelm. var. elliottii), compared to P. strobus, Picea species, bald cypress and gingko. P. elliottii var. elliottii was used as a representative species to investigate the chromosomal organization of telomere-like sequences by fluorescence in situ hybridization (FISH). The telomere-like sequences are not restricted to the ends of chromosomes; they form large intercalary and pericentric blocks showing that they are a repeated component of the slash pine genome.Conifers have genomes larger than 20000 Mbp, and our results clearly demonstrate that repeats of low sequence complexity, such to (CA)8, (GA)8, (GGAT)4 and (GATA)4, and minisatellite- and telomere-like sequences represent a large fraction of the repetitive DNA of these species. The striking differences in abundance and genome organization of the various repeat motifs suggest that these repetitive sequences evolved differently in the gymnosperm genomes investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051442
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  • 9
    Electronic Resource
    Electronic Resource
    The distribution, organization and evolution of two abundant and widespread repetitive DNA sequences in the genus Hordeum (2000)
    Springer
    Theoretical and applied genetics 100 (2000), S. 169-176 
    Details
    ISSN: 1432-2242
    Keywords: Key words Barley ; Hordeum ; In situ hybridization ; Phylogeny ; Tandemly repeated DNA sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The genomic organization and chromosomal distributions of two abundant tandemly repeated DNA sequences, dpTa1 and pSc119.2, were examined in six wild Hordeum taxa, representing the four basic genomes of the genus, by Southern and fluorescence in situ hybridization. The dpTa1 probe hybridized to between 30 and 60 sites on the chromosomes of all five diploid species studied, but hybridization patterns differed among the species. Hybridization of the pSc119.2 sequence to the chromosomes and Southern blots of digested DNA detected signals in Hordeum bulbosum, Hordeum chilense, Hordeum marinum and Hordeum murinum 4x, but not in Hordeum murinum 2x and Hordeum vulgare ssp. spontaneum. A maximum of one pSc119.2 signal was observed in the terminal or subterminal region of each chromosome arm in the species carrying this sequence. The species carrying the same I-genome differed in the presence (Hordeum bulbosum) or absence (Hordeum spontaneum) of pSc119.2. The presence of pSc119.2 in the tetraploid cytotype of Hordeum murinum, but its absence in the diploid cytotype, suggests that the tetraploid is not likely to be a simple autotetraploid of the diploid. Data about the inter- and intra-specific variation of the two independent repetitive DNA sequences give information about both the interrelationships of the species and the evolution of the repetitive sequences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050023
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  • 10
    Electronic Resource
    Electronic Resource
    High-resolution mapping of repetitive DNA by in situ hybridization: molecular and chromosomal features of prominent dispersed and discretely localized DNA families from the wild beet species Beta procumbens (1996)
    Springer
    Plant molecular biology 30 (1996), S. 1099-1113 
    Details
    ISSN: 1573-5028
    Keywords: Beta procumbens ; Beta vulgaris ; in situ hybridization ; repetitive DNA ; satellite DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Members of three prominent DNA families of Beta procumbens have been isolated as Sau3A repeats. Two families consisting of repeats of about 158 bp and 312 bp are organized as satellite DNAs (Sau3A satellites I and II), whereas the third family with a repeat length of 202 bp is interspersed throughout the genome. Multi-colour fluorescence in situ hybridization was used for physical mapping of the DNA families, and has shown that these tandemly organized families occur in large heterochromatic and DAPI positive blocks. The Sau3A satellite I hybridized exclusively around or near the centromeres of 10, 11 or 12 chromosomes. The Sau3A satellite family I showed high intraspecific variability and high-resolution physical mapping was performed on pachytene chromosomes using differentially labelled repeats. The physical order of satellite subfamily arrays along a chromosome was visualized and provided evidence that large arrays of plant satellite repeats are not contiguous and consist of distinct subfamily domains. Re-hybridization of a heterologous rRNA probe to mitotic metaphase chromosomes revealed that the 18S-5.8S-25S rRNA genes are located at subterminal position on one chromosome pair missing repeat clusters of the Sau3A satellite family I. It is known that arrays of Sau3A satellite I repeats are tightly linked to a nematode (Heterodera schachtii) resistance gene and our results show that the gene might be located close to the centromere. Large arrays of the Sau3A satellite II were found in centromeric regions of 16 chromosomes and, in addition, a considerable interspersion of repeats over all chromosomes was observed. The family of interspersed 202 bp repeats is uniformly distributed over all chromosomes and largely excluded from the rRNA gene cluster but shows local amplification in some regions. Southern hybridization has shown that all three families are specific for genomes of the section Procumbentes of the genus Beta.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019545
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