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  • 1
    Electronic Resource
    Electronic Resource
    Aging and diethylstilbestrol-induced aneuploidy in male germ cells: a transgenic mouse model (1998)
    Springer
    Chromosoma 107 (1998), S. 507-513 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The incidence of aneuploidy in male germ cells was evaluated by analyzing extra marker chromosome(s) signal(s) in round and/or hook spermatids of transgenic mice. Two types of transgenic mice were used as models. The inserted foreign DNA (λ-gt10LacZ shuttle vector and/or pSVc-myc plasmid) was located at the middle of the long arms of chromosome 2 (λ DNA) and/or chromosome 8 (c-myc). The number of marker chromosomes present could easily be detected after fluorescence in situ hybridization (FISH) in testicular cells. The frequency of spontaneous aneuploidy of chromosome 2 was similar in round spermatids of lambda and λ-myc mice. Differential involvement of chromosomes 2 and 8 was observed in both round and hook spermatids. The frequency of spontaneous aneuploidy in round spermatids was higher than that in hook spermatids. The frequency of aneuploidy of marker chromosomes was significantly higher in older mice (2 years old) than in younger ones. Diethylstilbestrol (DES)-induced aneuploidy was dose dependent, and was not influenced by the stage at which germ cells were treated with DES. These results demonstrate the usefulness of a transgenic mouse model for the study of aneuploidy in germ cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004120050336
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  • 2
    Electronic Resource
    Electronic Resource
    Localized chromosome breakage induced by ethyl-methane-sulfonate and hydroxylamine in Vicia faba (1964)
    Springer
    Chromosoma 15 (1964), S. 156-169 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Secondary root meristems of Vicia faba were treated with (a) 0.2% aqueous solution of ethyl-methane-sulfonate, for two hours, (b) aqueous solution of hydroxylamine (1 mg/ml) for 2 hours and (c) a mixture of these two agents in the proportion of 1∶1, for 1 hour; and allowed to revive. Root tips were fixed at various revival periods, from 12 hrs. to 84 hrs. These two agents are known to attack guanine and cytosine of the DNA molecule respectively. 2. Metaphase and anaphase breaks were screened and the breakage points were determined for the genome of Vicia faba. These breakage points were found to be localized and these regions were found to coincide with some of the known heterochromatic regions, of M and Sb chromosomes. Both the agents induced breaks in chromosomes exclusively on these points. 3. Centromeric regions were found to be affected by treatment with EMS as well as HA, as revealed by centric breaks as well as inactivation of centromeric activity. 4. The mechanism of action of these agents and the possible reasons for these localized effects are discussed. 5. From the data presented as well as those available in the literature on localized chromosome breaks with chemical mutagens, the possibility of mapping regions of chromosomes rich in guanine-cytosine pairs of bases and regions rich in adenine-thymine pairs of bases, is pointed out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00285727
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  • 3
    Electronic Resource
    Electronic Resource
    Chromosome breakage induced by alkyl-alkane-sulfonates under different physical treatment conditions (1966)
    Springer
    Chromosoma 18 (1966), S. 44-59 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A detailed study of chromosome breakage induced by three alkane sulfonates, which differ in chemical structure, functionality and reaction mechanism has been made in barley under different treatment conditions of temperature and hydrogen ion concentration. This study has indicated that, (i) the frequency and the types of chromosome breakage, at mitosis and meiosis, indicate certain qualitative and quantitative differences between the biological action of these three chemicals, (ii) the temperature of the treatment solution profoundly influences the frequency of chromosome breakage — a high frequency of breakage is observed at higher temperature, (iii) the effect of pH, though not very significant, is evident from the production of appreciably low frequency of breakage at alkaline pH for a given dose of chemical, (iv) by appropriate manipulation of treatment conditions, increase or decrease in the frequency of chromosome breakage can be accomplished to a considerable extent, (v) the qualitative and quantitative differences observed with respect to chromosoma breakage reflect the differences in the mode of biological action of these agents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326442
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  • 4
    Electronic Resource
    Electronic Resource
    Heterochromatin and chromosome aberrations (1969)
    Springer
    Chromosoma 28 (1969), S. 48-61 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The chromosome breaking effect of mitomycin C, methyl methanesulfonate, maleic hydrazide, 8-ethoxycaffeine and gamma rays on the primary root meristematic cells of Nigella damascena was studied. All the agents tested except 8-ethoxycaffeine, produced relatively fewer aberrations, when compared to Vicia faba cells, though both the species have nearly similar total chromosomal length. Test for the presence of heterochromatin in Nigella gave negative results and it is interpreted that the observed differences between Vicia and Nigella are due to the presence and absence of heterochromatin in their chromosome complements respectively. The role of heterochromatin in the production of chromosome aberrations and its significance in evolution are briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325989
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  • 5
    Electronic Resource
    Electronic Resource
    The localisation of radiation induced chromosome aberrations in relation to the distribution of heterochromatin in Secale cereale (1970)
    Springer
    Chromosoma 30 (1970), S. 250-257 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The distribution of two break chromosome exchanges (dicentrics and centric rings) following gamma or neutron irradiation of resting seeds of rye, Secale cereale, has been investigated. The localisation of heterochromatin in the terminal ends of the chromosomes of rye facilitates distinguishing aberrations involving heterochromatin from others. Dicentrics found in or near heterochromatic regions were about 5 times more frequent after gamma irradiation and about 2.5 times more after neutron irradiation, than expected on a random distribution. The implications of these findings in relation to aberration formation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00282004
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  • 6
    Electronic Resource
    Electronic Resource
    Differential response of constitutive and facultative heterochromatin in the manifestation of mitomycin induced chromosome aberrations in Chinese hamster cells in vitro (1971)
    Springer
    Chromosoma 33 (1971), S. 48-62 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The distribution of chromatid aberrations induced by mitomycin C among the individual chromosomes of female and male Chinese hamster cells in vitro was studied. The aberrations were found to be non-randomly distributed. Among the autosomes, the chromosomes possessing constitutive heterochromatin were more often involved in aberrations as well as in homologous exchanges. The inactivated X chromosomes in the female cells offer a situation where the short arm is facultatively heterochromatic and the long arm constitutively heterochromatic, thus enabling an analysis of their response for aberration formation. The short arm was seldom found to be involved in the aberration. The long arm of the inactivated X was more often affected (5 to 10 times) than the long arm of the functional X though both are constitutively heterochromatic. The possible role of (a) structure of heterochromatin, (b) the chromocenter formation and their association, (c) allocycly, and (d) the qualitative differences in the DNA of different types of heterochromatin are discussed in relation to the formation of chromatid aberrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326383
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  • 7
    Electronic Resource
    Electronic Resource
    Tritiated uridine induced chromosome aberrations in relation to heterochromatin and nucleolar organisation in Microtus agrestis L. (1971)
    Springer
    Chromosoma 34 (1971), S. 168-182 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Microtus agrestis is characterised by long sex chromosomes, most of which are constitutively heterochromatic, and thus supposedly, genetically inactive. A method to assess the template activity of the chromosomes is to study the distribution of chromatid aberrations produced by H3UdR, among and within the chromosomes. In such a study, in female Microtus agrestis cells in culture, it was found that, a large number of localised chromatid aberrations was induced in the constitutively heterochromatic regions of both X chromosomes. The frequency distribution and types of aberrations were found to be cell cycle dependent. With differential staining it has been possible to demonstrate that the constitutive heterochromatin of the sex chromosomes are involved in the nucleolar organisation in this species, thus containing the ribosomal RNA cistrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00285184
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  • 8
    Electronic Resource
    Electronic Resource
    Molecular mechanisms involved in the production of chromosomal aberrations (1984)
    Springer
    Chromosoma 90 (1984), S. 120-127 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Chinese hamster ovary cells (CHO cells) and mouse fibroblasts (PG 19) were permeabilized with inactivated Sendai virus, treated with different types of restriction endonucleases (Eco RV, Pvu II, Bam HI, Sma I, Asu III, Nun II), and studied for the occurrence of chromosomal aberrations at different times following treatment. The pattern of chromosomal aberrations observed was similar to that induced by ionizing radiations. Restriction endonucleases that induce blunt double-strand breaks (Eco RV, Pvu II) were more efficient in inducing chromosomal aberrations than those that induce breaks with cohesive ends (Bam HI, Nun II, Asu III). Ring types were very frequent among the aberrations induced by restriction enzymes. Cytosine arabinoside, an inhibitor of DNA repair, was found to increase the frequencies of aberrations induced by restriction enzymes, indicating its effect on ligation of double-strand breaks. The relevance of these results to the understanding of the mechanisms of chromosomal aberration formation following treatment with ionizing radiations is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292448
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  • 9
    Electronic Resource
    Electronic Resource
    Age-Related Accumulation of Mutations in Human T-Lymphocytes (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 663 (1992), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1992.tb38646.x
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  • 10
    Electronic Resource
    Electronic Resource
    Induction of Mutations in Barley with Ultra-violet Radiation (1963)
    [s.l.] : Nature Publishing Group
    Nature 199 (1963), S. 822-823 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] To facilitate maximum penetration, naked barley seeds (var. CN. 292), in which the embryos are situated in the periphery, and thus easily accessible to treatments, were used. An ultra-violet germicidal lamp, with a maximum output (86 per cent) at wave-length 2537 , was used. The seeds were ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/199822a0
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