Advances in Molecular Biology / Moleküler Biyolojide Gelişmeler

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Browsing Advances in Molecular Biology / Moleküler Biyolojide Gelişmeler by Author "Alexandrov, Igor"

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    PublicationOpen Access
    Spatial arrangement of the animal male germ cell genome: I. Non-random pattern of radiation-induced inversions involving the vestigial region in autosome 2 of Drosophila melanogaster
    (İstanbul Kültür Üniversitesi, 2007-03) Alexandrov, Igor; Alexandrova, Margarita V.; Korablinova, Svetlana V.; Korovina, Larisa N.
    At present, given a bulk of models for higher-order chromatin structure in interphase nuclei of animal somatic cells, little is known about the spatial chromosome organization in animal male germ cells mainly due to the lack suitable methods for detailed observation and analysis without disruption of the existing organization. We pioneered in the study of this issue via analysis of radiation-induced inversion patterns in Drosophila male germ cell genome taking into account the fact that the formation of inversion requires the spatial proximity and contact of its ends. Analysis of 72 γ- ray- or neutron-induced vg inversions in which the first break is invariantly associated with the vestigial (vg) gene in the middle of 2R autosome shows the second inversion breakpoints that highly non-randomly distributed over the entire second chromosome clustering at the three autosome 2 “hot” chromosome areas. These findings show that the polar Rabl-configuration of interphase chromosomes in various somatic cells is not typical for the haploid genome of Drosophila mature sperms. The specific megarosetteloopstructure of haploid chromosome in the mature animal sperms is proposed and justified.
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    PublicationOpen Access
    Spatial arrangement of the animal male germ cell genome: III. A new experimental evidences in support of the Megarosette-loop model of spatial organization of chromosomes in Drosophila sperm genome
    (İstanbul Kültür Üniversitesi, 2008) Alexandrov, Igor; Alexandrova, Margarita V.; Stepanenko, Victor A.; Korablinova, Svetlana V.; Korovina, Larisa N.; Stetsenko, Stanislav G.
    The data on the non-random pattern of induction of the black (b) inversions in autosome 2 after action of γ-rays of 60Co or 0.85 MeV fission neutrons on Drosophila mature spermatozoa were described and 2D model of spatial arrangement of this autosome in sperm nucleus at the time of irradiation based on these data was presented. The main features of this model found to be entirely consistent with the chromosome macroarchitecture proposed earlier on the basis of data for the vestigial (vg) inversions at the same autosome. A general 2D and 3D models for the specific megarosette-loop structure of autosome in question with both sets of the inversion data were constructed validity of which was independently confirmed by the induction patterns of inversions not associated with the locus-specific mutations under study. It is stated that there are all reasons to believe that all other chromosomes in sperm genome have the same spatial macroarchitecture as the most compact and suitable one to pass on the genetic information from one generation to another. It is particularly emphasized that large-scale chromosome geometry proposed is fundamentally unlike Rabl’s configuration of interphase chromosomes in animal somatic cells. The conversion of Rabl’s configuration to megarosetteloop structure is presumed to keep pace with protein remodeling of chromatin in late spermiogenesis.