Comparative cytogenetics of hamsters of the genus Calomyscus.

Karyotypes of Calomyscus from different regions of Turkmenistan, Iran, and Azerbaijan were studied using chromosome banding (G- and C-banding) and analyses of meiosis in laboratory hybrids. Extensive variation in the diploid number and the number of autosomal arms (FNa) was revealed (2n = 30, FNa = 44; 2n = 32, FNa = 42; 2n = 44, FNa = 46; 2n = 44, FNa = 58; 2n = 37, FNa = 44; 2n = 50, FNa = 50; 2n = 52, FNa = 56). Centric and tandem fusions and heterochromatin changes were identified as the major modes of karyotype evolution in this group. Natural hybrids between individuals with different karyotypes were recorded, and regular chromosome pairing in meiosis was observed in laboratory hybrids. Fluorescence in situ hybridization with a 353-bp BspRI complex tandem repeat indicated that chromosomal repatterning occurred recently within the genus. There is no unequivocal evidence suggesting the role of chromosomal change in the speciation of the populations of Calomyscus examined.

Localization of rat K51 keratin-like locus (Krt10l) to human and animal chromosomes by in situ hybridization.

The rat K51 locus (gene symbol Krt10l) was mapped using isotopic in situ hybridization to rat chromosome 3, human chromosome 9, pig chromosome 6, cattle chromosome 18, and mink chromosome 1.

Localization of ESD and A2M genes to sheep chromosome 3 by in situ hybridization.

The genes encoding esterase D (ESD) and alpha 2-macroglobulin (A2M) were mapped using 3H-labeled cDNAs to sheep chromosome 3p26-->p24 and 3q26-->q35 respectively.

[EcoRI- and BamHI-families of repeated sequences in mustelids]. / EcoRI- i BamHI-semeistva povtorov kunitseobraznykh.

The restriction enzymes EcoRI and BamHI digest the genomic DNAs from six mustelids species Mustela lutreola, M. vision, M. erminea, M. sibirica, Vormela peregusna, producing repeated fragments varying in length. Some fragments were hybridized to chromosomes and restriction digests of DNAs from some mustelids and other mammals. The 0.7 kb EcoRI repeats from DNA of M. erminea are dispersed over chromosomes of carnivors. The 1.35, 1.9 and 2.7 kb BamHI repeats from DNA of polecat M. putorius furo are specific for mustelids. These repeats demonstrate interspecific variation in length and the number of copies. All BamHI repeats have no strict tandem organization. The 1.9 kb BamHI repeats are concentrated in the heterochromatic pericentromeric regions and additional chromosome arms. The 1.35 kb BamHI repeats are only located in the centromeric regions of chromosomes of five species and are absent in Vormela peregusna.

[Phylogenetic relations of closely related species of Mustelidae. Interspecies variability of localization of restriction sites of BamHI-repeats]. / Filogeneticheskie otnosheniia blizkorodstvennykh vidov semeistva kunitseobraznykh. Mezhvidnaia izmenchivost', lokalizatsii restriktsionnykh saitov BamHI-povtorov.

The patterns of blot-hybridization of cloned BamHI repeats to genome DNAs were applied for estimation of phylogenetic relationships of closely related species (Mustela (L.) lutreola, M. (P.) putorius, M. (K.) sibirica, M. (M.) erminea, M. (L.) vision, Vormela peregusna). On the basis of information about interspecific distribution of the blot-hybridization bands (+, -) of BamHI repeats, phylogenetic tree was constructed, after selection of compatible characters, which revealed essential rate ununiformity during mustelids' evolution.

[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.

[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.

[Selective binding of tRNA by RNA dependent DNA-polymerase from Escherichia coli]. / Izbiratel'noe sviazyvanie tRNK RNK-3avisimoi DNK-polimerazoi Escherichia coli.

Highly purified RNA dependent DNA-polymerase was isolated recently from E. coli by Romashchenko et al. [8]. The present data demonstrate that total E. coli tRNA inhibits poly(dT) synthesis on poly (A): oligo (dT) catalyzed by the enzyme when the enzyme:tRNA ratio is about 1 : 80--100. The inhibition results from the binding of certain tRNA's by the enzyme. The enzyme tRNA complex was separated from the unbound tRNA's by gel-filtration of Sephadex G-100. The tRNA's extracted from the complex are able to inhibit completely poly(A):oligo(dT) templated synthesis of poly(dT) under the enzyme:tRNA ratio about 1 : 2--3. Aminoacylation of tRNA separated from the enzyme complex has shown that E. coli RNA dependent DNA-polymerase selectively binds tRNAThr and to a lesser extent tRNATyr and tRNALys. It is suggested that the enzyme bound tRNA's carry out the functions of natural primers which compete with oligo(dT) for the enzyme responsible for the primer binding.