[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 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 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 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.

[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.

[A new approach to the analysis of complex chromosomal rearrangements in cell hybrids]. / Novye vozmozhnosti analiza slozhnykh khromosomnykh perestroek v kletochnykh gibridakh.

The chromosomal complements of somatic cell pig-mink hybrids was determined by a new approach. This approach includes microdissection of metaphase chromosomes, generation of chromosome and region-specific DNA libraries, and fluorescence in situ hybridization of these libraries with pig lymphocyte chromosomes. The studied hybrid cells were shown to contain two small acrocentric chromosomes and a microchromosome of porcine origin. Identification of these chromosomes by differential GTG-staining was impossible. Chromosome isolation by a micromanipulation technique followed by DNA amplification in TOPO-DOP polymerase chain reaction provided chromosome-specific DNA libraries of the rearranged chromosomes. Based on these libraries, the labeled DNA probes were prepared and hybridized to pig chromosomes. This allowed us to determine the origin of the material contributing to the hybrid cell chromosomes. One of these chromosomes contained five pig chromosomal regions: 15cen-q2; 6q21-q23; 13q21; 13q22; 7q25-qter, while the other contained the following pig chromosomal regions: 4p12-p13; 16q12-q14; 12pter-p15. The microchromosome contained the Xp11-Xq11 region. The minimal size of the revealed chromosomal regions was about 3 to 4 x 10(6) bp. Segregation analysis of the thymidine kinase gene 1 (TK1), which was earlier localized to the pig 12p region, and the hybrid cell pig chromosomes in the hybrid subclones suggested that TK1 gene can be assigned to 12p15-pter. The results obtained demonstrate the efficiency of the applied approach in its detailed and reliable description of complex chromosomal rearrangements in hybrid clones, when differential chromosome staining failed to identify these chromosomes.

[Cosmid libraries containing DNA from human chromosome 13]. / Issledovanie kosmidnykh bibliotek, soderzhashchikh DNK khromosomy 13 cheloveka.

We characterized two cosmid libraries constructed from flow-sorted chromosome 13 at the Imperial Cancer Research Fund (ICRF), UK (13,000 clones) and Los Alamos National Laboratory (LANL), USA (17,000 clones). After storage for two years, clones showed high viability (95%) and structural stability. EcoR I and Hind III restriction patterns were studied in more than 500 ICRF and 200 LANL cosmids. The average size of inserts was shown to be 35-37 kb in both the libraries. Most cosmids (83% and 93% of ICRF and LANL libraries, respectively) exceed the lower size limit of DNA fragments that can be packaged and represent a good source for physical mapping of chromosome 13. Total length of inserts is four and five genome equivalents in the ICRF and LANL libraries, respectively. ICRF cosmids showed hybridization to 22 of 24 unique probes tested, which corresponds to a 90% probability of having any DNA fragment represented in the library. More than 1 Mb of chromosome 13 is overlapped by 90 cosmids of 22 groups revealed. A chromosomal region of more than 150 kb, containing the ATP1AL1 gene for alpha-1 peptide of Na+, K(+)-ATPase, is covered by 12 cosmids forming a contig. The results of restriction and hybridization analyses are stored in a CLONE database. These data and all the cosmids described are publicly available.

[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.

[A new case of trisomy in cattle]. / Novyi sluchai trisomii u krupnogo rogatogo skota.

The new type of trisomy (2n = 61, XX, +19) was found in the heifer with prognathia inferior syndrome. Correlations between trisomy of different types and phenotypic abnormalities are discussed.

[A new chromosomal rearrangement in cattle]. / Novaia perestroika khromosom u krupnogo rogatogo skota.

The karyotype of a heifer with 2n-59 was studied using routine, C- and high-resolution G-banding techniques. A 1/29 translocation was identified. One of X chromosomes was normal. Another X chromosome was absent, but G-positive, partly heterochromatic biarmed element was present in all the cells. It is supposed that deletion of greater part of the q-arm of the second X chromosome and heterochromatinization of the remains took place.

[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.