Meiosis in gray voles of the subgenus <Emphasis Type="Italic">Microtus</Emphasis> (Rodentia,Arvicolinae) and in their hybrids |
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Authors: | L D Safronova F N Golenishchev E V Cherepanova M I Baskevich |
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Institution: | 1.Severtsov Institute of Ecology and Evolution,Russian Academy of Sciences,Moscow,Russia;2.Zoological Institute,Russian Academy of Sciences,St. Petersburg,Russia |
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Abstract: | The results of light and electron microscopic (EM) studies of meiosis in Microtus arvalis males of the karyoform “arvalis” (2n = 46, NFa = 80), in hybrids between the chromosomal forms arvalis and obscurus (2n = 46, NFa = 68), in M. rossiaemeridionalis voles (2n = 54, NFa = 54), and in a hybrid between the species M. rossiaemeridionalis and kermanensis (2n = 54, NFa = 54) are presented. SC (synaptonemal complex) karyotypes of the parental forms and the hybrids were constructed
on the basis of measurements of the length of autosomal SCs revealed by the EM analysis in spermatocytes at the stage of middle
pachytene. The SC karyotypes of M. arvalis and the hybrids ♀ obscurus × ♂ arvalis consist of 22 synaptonemal complexes of autosomal bivalents and the axial elements
of the synaptonemal complexes of the sex chromosomes X and Y. The SC karyotypes of M. rossiaemeridionalis and the hybrid M. rossiaemeridionalis × M. kermanensis consist of 26 synaptonemal complexes of autosomal bivalents and a sex bivalent; they differ only in the length of the Y chromosome
axis (Y chromosome in the hybrid was inherited from M. kermanensis). Asynaptic configurations of the autosomal SCs were not observed in the hybrids. The SC axial elements of the X and Y chromosomes
in the parental forms and in the hybrids were located close to each other throughout pachytene, but they did not form a synaptic
region. The normal synapsis in sterile hybrids (M. rossiaemeridionalis × M. kermanensis) and the behavior of the sex chromosomes in meiosis in fertile and sterile hybrids are discussed in the context of specific
features of meiosis and reproductive isolation. |
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