[Karyotypic instability of peripheral blood lymphocytes in cows Bos taurus L. infected with bovine leukemia virus]. / Kariotipicheskaia nestabil'nost' limfotsitov perifericheskoi krovi korov Bos taurus L., infitsirovannykh virusom leikoza krupnogo rogatogo skota (KRS).

Chromosomal aberrations (CAs), sister-chromatid exchanges (SCEs), aneuploidy and proliferative potential (PP) were investigated in peripheral blood lymphocytes of healthy cows (control group-C), BLV-(bovine leucosis virus)-infected cattle without hematological abnormalities (RID--seropositive group (I) and affected with leucaemia (lymphocytosis (LC), lymphoma (L)). Nonrandom chromosomal (marker) aberrations were not found in the cow group at stage LC. The levels of aneuploidy and SCEs increased in the cow group at stage L compared to the cow group at stage I. Polyploidy: C--1.9 +/- 0.28, I--3.5 +/- 0.22, LC--6.1 +/- 0.82, L--10.5 +/- 0.51 (P < 0.01). Hypoploidy (2n = 58): C--3.0 +/- 0.17, I--54 +/- 0.71, LC--12.1 +/- 0.72, L--14.0 +/- 0.65 (P < 0.01). SCEs: C--3.8 +/- 0.26, I--5.4 +/- 0.15, LC--7.2 +/- 0.16, L--9.7 +/- 0.26 (P < 0.01). There are no differences in CAs rates and PP between groups of cows at all the observed stages of leucaemic process. The obtained results are discussed in terms of cytogenetic aspects of leucaemic process in cows.

[Heterochromatin and euchromatin regions in the chromosomes of various representatives of the subfamily Bovinae]. / Geterokhromatinovye i éukhromatinovye raiony khromosom nekotorykh predstavitelei podsemeistva Bovinae.

Heterochromatin distribution was studied in three species of subfamily Bovinae: bison (Bison bison), European bison (Bison bonasus), and gayal (Bos frontalis). In all of the studied species, C- and CMA3-banding and in situ hybridization with satellite DNAII (satDNAII) revealed the conservative distribution of heterochromatic regions in autosomes; sex chromosomes did not contain the classical constitutive heterochromatin. The Y chromosome was the most variable element of the karyotypes of both bison species and the gayal. A mechanism for formation of the acrocentric Y chromosome in B. bison was suggested. This hypothetical mechanism included breakage of the p arm at the telomeric region and subsequent translocation and inversion. The map of B. bison chromosomes (491 bands per haploid set) is presented. The data obtained are discussed in terms of speciation and the evolution of Bovinae karyotypes.

[Patterns in the condensation of bovine chromosomes in the prophase-late metaphase of mitosis]. / Zakonomernosti kompaktizatsii khromosom krupnogo rogatogo skota v profaze--pozdnei metafaze mitoza.

A comparative analysis of Bos taurus L. cytogenetic maps of different resolution levels was used to study principles of fusion R(G)-bands during chromosome condensation from prophase to the late metaphase. Three different types of fusion have been demonstrated, differing in quantity of interacting bands and fusion mechanism. Preferential condensation zones with constant localization was found. By means of the fusion index, faster condensation of R-bands than that of G-bands was revealed. Relevant data on B. taurus and Homo sapiens were compared. The obtained results are discussed in terms of common problems of mitotic chromosome R(G)-banding nature in warm-blooded animals.