[The role of chromosome rearrangements in evolution of mole voles of genus Ellobius (Rodentia, Mammalia)].

Modern mole voles of the genus Ellobius are characterized by species-specific features of autosomes and sex chromosomes. Owing to the use of the Zoo-FISH method, the nomenclature of chromosomes was refined and nonhomologous Robertsonian translocations indistinguishable by G-staining were identified for Ellobius tancrei, which is a species with a wide chromosome variation of the Robertsonian type. The electron-microscopic analysis of synaptonemal complexes in F1 hybrids of forms with 2n = 50 and 2n = 48 revealed the formation of a closed SC-pentavalent composed of three metacentrics with monobrachial homology and two acrocentrics.

[Dynamics of chromosome variation in mole voles Ellobius tancrei (Mammalia, Rodentia) in Pamiro-Alai in the period from 1982 to 2008].

Analysis of a new karyological material of mole voles Ellobius tancrei from a zone of high chromosome variation (Pamiro-Alai) in comparison with the data obtained 25 years ago showed a slight shift of the chromosome numbers on the western border of the Robertsonian fan due to the expansion of the area of forms with a low chromosome number. In the central part of the fan zone, the process of active hybridization of forms with different chromosome numbers, but not of the original forms, is still going on. Some problems of speciation on the basis of Robertsonian translocations are discussed.

[Evolution of the sex determination in mammals].

This review summarizes current concepts concerning the evolution of sex chromosomes and the cascade of sex-determining genes in mammals. Untypical sex-determination systems in rodents lacking the Y-chromosome and Sry gene are considered using Ellobius as an example.

[Chromosomal polymorphism in mole rat Spalax microphthalmus (Rodentia, Spalacidae) from results of differential staining].

Differential stained chromosomes of the mole rat Spalax microphthalmus Guld. (Rodentia, Spalacidae) (2n = 60; NF = 110-112) from Streletskaya and Kazatskaya steppes (Kurskaya oblast, Russia) are described. Animals heterozygous for a complex chromosome rearrangement resulting in increased chromosome size and altered location of the centromere were revealed.