[Supernumerary chromosomes, segmental duplications, and evolution].

The present study depicts the phenomenon of supernumerary chromosomes as autonomous genome elements, similar in features with segmental duplications. Possible role of B chromosomes in evolution and the reasons of their nonrandom distribution in different mammalian taxa are discussed.

[Comparative cytogenetics of rodents].

Here, we present analysis of data on comparative chromosome painting produced using various chromosome-specific libraries for members of different Glires groups. Based on the results of comparative cytogenetic and molecular studies, the modern rodents can be conventionally classified into two groups with sharply differing directions and tempoes of karyotypic evolution. One group (suborders Sciuromorpha, Castorimorpha, and Anomaluromoprpha) preserved conserved genomes, which are probably close in structure to the genome of the ancestor of all mammals. The genomes of the other group (suborder Myomorpha) underwent "catastrophic evolution," which resulted in numerous breaks and fusions of the ancient chromosomes. The current data do not allow unambiguously assigning the order Hystricomorpha to any of these groups.

[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. Segregation of chromosomes of such complex systems is impeded by disturbances in the nucleus architecture leding to the formation of unbalanced gametes and to a dramatic reduction in fertility of hybrids. Our data support the hypothesis that the formation of monobrachial homologous metacentric chromosomes can be considered as a way of chromosomal speciation.

[Analysis of chromosome composition in interspecific embryonic stem hybrid cells of mice].

Chromosome complements of twenty hybrid clones obtained by fusion of Mus musculus embryonic stem cells (ESC) and M. caroli splenocytes were studied. Using of double-color in situ hybridization with chromosome- and species-specific probes we were able to detect the parental origin for each chromosome in hybrid cells. Based on parental chromosome ratio, all 20 hybrid clones were separated in some different groups: from the group containing practically tetraploid M. musculus genome with single M. caroli chromosomes to hybrids with dominance of M. caroli chromosome homologues. In 8 hybrid cells clones we observed prevalence of chromosomes originated from ESC in ratio from 5:1 to 3:1. Another hybrid cells clones have either equal (1:1, 1:2) ratio of M. musculus to M. caroli chromosomes or with the prevalence of ESC- (2:1) or splenocyte- (1:2) originated parental chromosome homologues. In 3 hybrid cells clones, we observed preferable segregation of ESC-originated pluripotent chromosomes. This phenomenon was found for the first time and it possibly indicates compensation of the epigenetic differences between parental chromosomes of ESC- and splenocyte-origination.

[Comparative cytogenetics of main Laurasiatheria taxa].

This short communication is a review of key trends in the karyotypic evolution of mammalian taxa Laurasiatheria, inferred from comparative chromosome painting.

[Comparative chromosomics].

In the presented review features of the organization and evolution of chromosomes and genomes of animals, first of all mammals are discussed. Modern basic approaches to comparative genomes mapping are described.

[Analysis of expression of parental alleles Xist and Gla in interspecific embryonic hybrid cells during induced in vitro inactivation of X-chromosomes].

The results of in situ hybridization with labeled species specific and X-chromosome-specific probes suggest that hybrid cells obtained by fusion of Mus musculus embryonic stem cells (genotype XY) and splenocytes of M. caroli females contain two parental X-chromosomes. In five clones of hybrid cells, differentiation was induced in embryoid bodies in vitro, which was accompanied by inactivation of one of X-chromosomes. We analyzed the expression of Xist and Gla alleles in the embryoid bodies using RT-PCR with an account that expression of locus Xist is one of key events in X-chromosome inactivation, while gene Gla was used as a marker of active X-chromosome. Identification of allele transcripts of loci Xist and Gla was based on restriction polymorphism between M. musculus and M. caroli that we had described. Transcripts of both parental alleles of loci Xist and Gla were present in the embryoid bodies of all studied hybrid clones. No preferential inactivation of M. musculus or M. caroli X-chromosome was found in the tested embryonic hybrid cells despite the initial differences in ontogenetic status between X-chromosomes of embryonic stem cells and splenocytes.

[Interstitial telomere repeats as markers of evolutionary changes in the mammalian karyotype: human chromosome 2].

Telomer repeats represented by hexamer (TTAGGG)n at chromosome termini are required for correct function and chromosome stability. At the same time, interstitial telomer sequence (ITS) located far from the chromosome ends are known for several mammalian genomes, including the human genome. It is assumed that these repeats mark the points of fusion or other chromosome reconstructions of ancestors. Exact localization of all interstitial telomer sequences in the genome could greatly improve our understanding of the mechanism of karyotype evolution and species origin. We have developed a software for a search of interstitial telomer sequences in complete sequences of mammalian genomes. We have demonstrated the evolutionary significance of repeats by an example of human chromosome 2. The results and supplementary materials are available at the site of the Institute of Cytology and Genetics: http://www.bionet.nsc.ru/labs/theorylabmain/orlov/telomere/.

[Development and certification of libraries of the MDCK continuous cell line for production of influenza vaccine].

Seeding and working banks of the continuous MDCK cell culture suitable for the production of cultured influenza vaccine were created and deposited at liquid nitrogen temperature at the "Vector" State Research Center of Virology and Biotechnology. The MDCK cell culture was shown to have morphology typical of the discussed cell line; it does not have any alien agents and is oncogenically safe; its enzimogram and karyotype are typical of the donor line; finally, its biological properties are stable during a long period of cultivation and its sensitivity to influenza virus is high, therefore, it can be recommended for the production of influenza vaccine. The continuous MDCK cell line was certified at Tarasevich Committee and was recommended by the MIBP Committee, Russia's Health Ministry, for its use as a substrate in the production of diagnostic and preventive immunoglobulins.

[Modification of DNA with 4-aminooxybutylamine as a method for obtaining highly-sensitive hybridization probes. Mapping of the gene for human chorionic somatomammotropin hormone]. / Modifikatsiia DNK 4-aminooksibutilaminom kak sposob polucheniia vysokochuvstvitel'nykh gibridizatsionnykh zondov. Lokalizatsiia gena khorionicheskogo somatomammotropnogo gormona cheloveka.

A new method for preparation of highly sensitive nonradioactive probes for dot, dot-blot and in situ hybridization was developed. The method is based on chemical modification (transamination) of cytosine residues with 4-aminooxybutylamine following by coupling biotin or fluorescein to aliphatic aminogroups introduced into DNA. Such a probe have been used for detection of gene encoding chorionic somatomammotropin hormone (hCS) in genomic blot hybridization. The gene hCS was mapped using isotopic and nonisotopic in situ hybridization on human chromosome 17.

[Characteristics of the pH2-42 probe for the D13S25 locus of human chromosome 13: nucleotide sequence, localization, and PCR markers]. / Kharakteristika proby pH2-42 lokusa D13S25 13-i khromosomy cheloveka: nukleotidnaia posledovatel'nost', lokalizatsiia, PTsR-markery.

The sequence of the HindIII-HindIII fragment of probe pH2-42 of locus D13S25 of human genome is given. Localization of the probe in q14-q21 of human chromosome 13 is confirmed by hybridization in situ. Seven oligonucleotide primers for the polymerase chain reaction are chosen so that amplified products almost completely cover the analyzed sequence. Reconstruction of localization of polymorphic SspI-sites in D13S25 was based on the data of Bowcock and Hebert [3] and this study. The results obtained make it possible to use the primer sets to screen cosmid libraries and to mark the D13S25 locus of human chromosome 13.

[Homology of G-banded mammalian chromosomes]. / Gomologiia G-okrashennykh khromosom mlekopitaiushchikh.

Linkage relationships of homologous loci and high resolution G-banding patterns of man, mouse, rat, chinese hamster, rabbit, cat, mink, pig, ox and sheep were used for identification of 11 evolutionary conservative autosomal regions. The distributions and inversions of these regions in the ancestor genomes of some phylums have been shown. For example, the regions homologous to human Ip region were detected in cat, mink and rabbit genomes. In the genomes of rodents studied the intraregion inversion was detected. In the ox and sheep genomes the distal end deletions were detected within these regions. In the pig genome these regions were represented solely by disruptions. We supposed that the rapid "catastrophic" chromosomal evolution took place during short time periods of some orders and families separation.

[Characteristics of the distribution of DNA repetitive sequences in the sex chromosomes of 4 species of rodent]. / Osobennosti raspredeleniia povtoriaiushchikhsia posledovatel'nostei DNK v polovykh khromosomakh chetyrekh vidov gryzunov.

Four rodent species with very large heterochromatic regions on the sex chromosomes have been studied using in situ DNA/DNA hybridization techniques. Repetitious DNA fractions were obtained at C0t 0-0.01. Heterochromatic regions of X and X chromosomes of Cricetulus barabensis and Phodopus sungorus, and the heterochromatic long arm of the Y chromosome of Mesocricetus auratus do not contain disproportionately high amounts of repeated DNA sequences. Heterochromatic regions on sex chromosomes of Microtus subarvalis contain high amounts of repeated DNA sequences. Additional heterochromatic autosomal arms, a heterochromatic arm of the X chromosome, and a short arm of the Y chromosome of Mesocricetus auratus contain high amounts of repeated DNA sequences too.

[Comparative chromosome painting]. / Sravnitel'nyi khromosomnyi péinting.

The review of the data on comparative chromosomal painting in mammals is presented. The development of new molecular-cytogenetic methods has resulted in the accumulation of the detailed information on homology of chromosomal segments of more than 50 species from 11 orders. In this review, modern methods of obtaining painting probes are considered in detail, and the basic tendencies of karyotype evolution in different taxa are discussed. Putative karyotypes of the ancestors of primates, carnivores, and placental mammals are considered.

[Cytogenetics of albinism in polecats of the genus Putorius (Carnivora, Mustelidae)]. / Tsitogenetika al'binizma u khor'kov roda Putorius (Carnivora, Mustelidae).

Karyotypes of two ferret species, Putorius eversmanni (2n = 38) and P. putorius (2n = 40), differ in a single Robertsonian rearrangement, resulting in decreased chromosome number in P. eversmanni. Interspecific hybrids from crosses between P. eversmanni and domesticated albino ferret P. putorius furo are fertile. Hybrid individuals have a chromosome set 2 = 39. Analysis of offspring from crosses of these hybrids showed that albinism is a recessive character. Offspring obtained from crosses between interspecific hybrid ferrets and between these hybrids and parental species was subjected to chromosome analysis. A statistically significant correlation was observed between the chromosome number and albinism. As a rule, albino hybrids have a chromosome number 2n = 40. This suggests that the locus, controlling albinism, is located at one of the two pairs of acrocentric chromsomes involved in Robertsonian rearrangement. The rare occurrence of albino hybrids with 2n = 39 may be attributed to recombination. According to our data, recombination probability is less than 0.5 which indicates that the albinism locus located near the centromere. Possible extrapolation of the data obtained for ferrets to other Mustelidae is discussed.

[Genome mapping of the silver fox. I. Determination of the chromosomal location of 8 fox genes and the search for homologous regions on fox and human chromosomes]. / Kartirovanie genoma serebristo-chernoi lisitsy. Soobshchenie I. Opredelenie khromosomnoi lokalizatsii vos'mi genov lisitsy i poisk gomeologichnykh raionov khromosom lisitsy i cheloveka.

Twenty-three silver fox-Chinese hamster somatic cell hybrids were analysed for the expression of fox enzyme loci and the segregation of fox chromosomes. This analysis made it possible to assign the gene PGD to chromosome 2, MDH2 to chromosome 3. NP to chromosome 10. APRT, ENO1, PGM1 to chromosome 12, MDH1 and IDH1 to chromosome 16. Possible use of the above-mentioned clone panel for fox gene mapping is analysed. An attempt to reveal homologous regions on fox and human chromosomes was made by comparative analysis of prometaphase fox and human chromosomes containing the homologous genes. The means and perspectives of verification of the hypothesis proposed are discussed.

[Chromosomal localization and evolutionary age of satellite DNAs of Mustelidae]. / Khromosomnaia lokalizatsiia i évoliutsionnyi vozrast satellitnykh DNK kunitseobraznykh.

DNA reassociation kinetics were studied in the European mink (Mustela lutreola), the American mink (M. vison), the marbled polecat (Vormela peregusna). Variation in DNA quantity and heterochromatin amount occurs in connection with changes in the size of all kinetic fractions. Moderately repetitive genome component is the most variable in these three species. Cryptic CsCl satellite of the stoat (M. erminea), Ag+/Cs2SO4 satellites of the M. vison, V. peregusna were used for in situ homo- and heterologous hybridizations. Satellite DNAs revealed may be classified for the evolution age and chromosomal location type. More ancient satellite DNAs were dispersed in carnivors or mammalian genomes. Mustelids' specific satellites are concentrated in heterochromatic chromosome regions. The evolutionary implications of these findings are discussed.

[Genome mapping in silver fox. Syntenic genes in Carnivora]. / Kartirovanie genoma serebristo-chernoi lisitsy. Sintennye otnosheniia genov u khishchnykh.

Hamster X fox somatic cell hybrids segregating individual fox chromosomes in different combinations were used to assign seven structural loci to fox chromosomes. The gene for ME1 was mapped on the VFU1 chromosome, the genes for ADK and PP being located on the VFU4 chromosome. The gene for GSR was assigned to the VFU7 chromosome and the genes for MPI and COT1 were assigned to the VFU15 chromosome. Localization of these genes enhances the established fox genetic map and extends the known syntenic homologies between the fox and other mammalian. The comparison of data on gene mapping has provided basis for suggestion that there are significant differences in rates of karyotypic evolution in many mammalian taxa.

[Karyotypes of 5 species of Soricidae-Crocidura in the fauna of the USSR]. / Kariotipy piati vidov zemleroek-belozubok fauny SSSR.

The chromosomes of five Crocidura species have been studied by means of routine, G-, C- and Ag NOR-banding techniques. The karyotypes of the species with 2n = 40, i.e. C. gueldenstaedtii, C. suaveolens and C. sibirica, are identical. Short arms of the Y-chromosome of C. sibirica are larger. The karyotypes of C. leucodon (2n = 28) and C. zarudnyi (2n = 22) could be obtained as a result of tandem and centric fusion and pericentric inversions. Small amounts of heterochromatin were detected in autosomes of the species investigated. The Y-chromosomes are completely heterochromatic. Four NOR-bearing pairs are detected in the species investigated.