[T-specific D17Leh66 DNA elements in family Muridae].

Blot-hybridization analysis with the use of the t-specific probe D17Leh66 has been used to study DNA of various representatives of family Muridae. Hamsters from genus Phodopus have no homologs of this probe, whereas African rats from genus Lophuromys have some homologous elements. This indicates that sequence Dl7Leh66 is ancient and was probably present in the common ancestor of family Muridae.

[Genetic and molecular characteristics of a new natural haplotype twMP1 of the house mouse (Mus domesticus R.) from Peru]. / Geneticheskaia i molekuliarnaia kharakteristika novogo prirodnogo gaplotipa twMP1 domovoi myshi (Mus domesticus) iz Peru.

A new natural haplotype, twWP1, found in a population of house mouse Mus domesticus from Peru, was subjected to genetic and molecular analyses. Experiments were performed to study the complementation of the new haplotype, fertility of twMP1/tx heterozygotes, and transmission ratio distortion (TRD) of the t-carrying chromosome in the progeny of heterozygous males. Molecular analysis included blot hybridization with t-specific probes Tu48, Tu66, and Tu119. The results were collated with the structure and properties of the t complex, and the new haplotype was identified as a complete lethal one.

[Structural organization and evolution of t-complex in Mus genus]. / Strukturnaia organizatsiia i évoliutsiia t-kompleksa u predstavitelei roda Mus]

Modern data on the structure and evolution of the t complex are discussed. The t complex is a series of inversions in the proximal region of murine chromosome 17; it contains a set of genes that determine its predominant transmission to the offspring of heterozygous males. Variants of structural organization of this genetic system (t haplotypes) have been found in wild populations of four species of genus Mus (M. domesticus, M. musculus, M. molossinus, and M. castaneus), but not in representatives of other, evolutionarily remote species of this genus. The so-called vertical, horizontal, and introgressive hypotheses are discussed of the origin and evolution of the t complex. Based on population genetic studies and molecular analysis a new hypothesis on the origin of the t-complex is put forward. This hypothesis is a synthesis between the vertical and horizontal models and assumes that all known t haplotypes had a common ancestral chromosome 17 carrying a proximal inversion.

[Characterization of a novel wild-type t(wMPI) haplotype of the house mouse (Mus domesticus L.) from Peru]. / Kharakteristika novogo prirodnogo gaplotipa t(wMPI) domovoi myshi (Mus domesticus L.) iz Peru.

Data on molecular genetic analysis of the novel wild-type twMP1 haplotype found in a population of Mus domesticus from Peru are presented. Complementation attribution of the novel haplotype as well as fertility of heterozygotes and transmission ratio distortion (TRD) of the t-carrying chromosome in the progeny of the heterozygous males were studied. Molecular analysis was carried out by means of blot hybridization with the four t-specific probes (Tu48, Tu66, Tu119, and Tu122). Comparison of the results obtained with the data on the structure and properties of the t complexes permitted conclusion on the complete lethality of the haplotype described.

[Effect of an increased radiation background on mice, carrying lethal t-haplotypes]. / Vliianie povyshennogo radiatsionnogo fona na myshei, nesushchikh letal'nye t-gaplotipy.

To study the effect of a high radiation background on the structure and function of the T-complex, we used laboratory mice carrying t-haplotypes of four complementation groups (t0, t12, tw1, and tw5). In 1987-1989, the animals were kept each year for a month within a 30-kilometer zone of Chernobyl Nuclear Power Station in regions with different degrees of pollution. Subsequent genetic analysis revealed a decrease in fertility, fecundity, and the index of preferable transmission of t-carrying chromosomes in radiated animals and some of their progeny. The effect of different radiation doses on these parameters was different in animals with various t-haplotypes. A lack of complementation or a decrease in the complementation effect was revealed in a number of crosses involving the progeny of irradiated animals. The frequency of complementation distortion was about 8 x 10(-2), which is more than an order higher than the usual recombination frequency characteristic of these t-haplotypes.

[Polymorphism of t-specific DNA elements of the proximal part of chromosome 17 in mice of Mus genus]. / Polimorfizm t-spetsifichnykh DNK-élementov proksimal'noi chasti khromosomy 17 u myshei roda Mus.

To study structural organization and polymorphism of the proximal part of chromosome 17, a hybridization analysis of DNA from mice of different origin was carried out using four t-specific probes. Results of the analysis allow us to conclude that the DNA element copy number is quantitatively unstable and differs in distribution in both newly formed recombinant haplotypes and in wild-type chromosome 17. probe Tu66 was used to study D17Leh66-element organization of Mus abbotti and Mus hortulanus mice. Three types of D17Leh66-elements were identified in the genomes of these species. The copy number of each type of DNA element varied in the genome of each of four studied species. Homologs to t-specific Tu66 and Tu119 probes were found in the genome of Rattus norvegicus rat. The data obtained are discussed with respect to the evolution of the proximal part of Mus mouse chromosome 17.

[Genetic and molecular analysis of new recombinant t-haplotypes t(M8) and t(M9)]. / Geneticheskii i molekuliarnyi analiz novykh rekombinantnykh t-gaplotipov t(M8) i t(M9).

The results of genetic and molecular analysis of new recombinant mouse haplotypes tM8 and tM9, derived from tw12 and t12, are described. Data on viability and fertility of tM/tM homozygotes are presented, as well as that on t-chromosome transmission ratio distortion (TRD) in the progeny of heterozygous males. Blot-hybridization analysis was performed using four t-specific probes: Tu48, Tu66, Tu119, and Tu122. Comparison of data obtained in the study with that on the structure of the initial haplotypes suggests that both recombinant haplotypes resulted from unequal crossing-over. In the case of tM9 haplotype, the crossing-over site was probably located in the region of distal t complex inversion, and tM8 haplotype resulted from two crossing-over events in the medial part of t complex.

[Disturbance of the relationship of transmission in male mice carrying the translocation Rb(8,17)1 Iem in combination with t-haplotypes]. / Narushenie sootnosheniia peredachi u samtsov myshei nesushchikh translokatsiiu Rb(8,17)1 Iem v sochetanii s t-gaplotipami.

t-complex typical feature of the house mouse 17th chromosome is the high transmission (up to 90-95%) of t-carrying chromosome to heterozygous +/t male offspring. The influence of Robertsonian translocation Rb1 (8, 17) Iem at t-haplotype transmission TRD level of heterozygotes Rb1+/+t6, Rb1+/+t12, Rb1+/+tw5, Rb1+/+tw18 in crossing with females of different genotypes was studied. Reliable decrease of TRD level in double heterozygotes of Rb1 and haplotypes t12, tw5, tw18 in comparison with the males ++/+t was discovered. For haplotype t6 no differences in TRD between Rb1+/+t6 and ++/+t6 were recorded. The cause of the obtained results is discussed.

[Characterization of novel partial t-haplotypes tM1, tM2, tM3, tM4]. / Kharakteristika novykh chastichnykh gaplotipov tM1, tM2, tM3, tM4.

The results of genetic analysis of the effects of four novel partial mouse TM-haplotypes are presented in this work. Fertility and viability of tM/tM homozygotes and tM/t6 compounds, transmission ratio distortion (trd) in males heterozygous for tM, suppression of recombination and taillessness effects were studied. Three novel t-haplotypes tM1,2,4 are viable and heterozygous for these haplotypes males T/tM show low trd (20-30%). Comparison of these data and the t6-haplotype structure suggests that the tM1,2,4-haplotypes were derived as a result of recombination events in the non-inverted T-complex fragment located between two inversions. The tM3-haplotype is semilethal and heterozygous T/tM3 males show the trd equal to that of t6-heterozygotes. Homozygous tM3/tM3 and tM3/t6 male compounds are fertile or subfertile. Potential recombination ways of derivation of tM3 are discussed.

[Genetic analysis of fertility of male mice with various t-haplotypes]. / Geneticheskii analiz fertil'nosti samtsov myshei, nesushchikh razlichnye t-gaplotipy.

Fertility of 47 mouse males carrying various combinations of lethal, t-haplotypes (t6/tw18, t12/tw18, Tw73/tw12, tw5/tw18, t6/dt5, t12/tw12, tw5/twPa-1, tw18/twPa-1, tw5/tw12) was studied in crosses with females of different genotypes. The t-haplotypes studied belong to 7 main groups of complementation. The presence of at least two factors of fertility in the t-complex was revealed. The influence of female genotype on the degree of male fertility was also demonstrated. The data presented confirm that different combinations of lethal complete t-haplotypes exhibit sterility, with the exception of t8/tw18 compound.

[Genetic analysis of complementation of t-haplotypes in mice]. / Geneticheskii analiz komplementatsii t-gaplotipov myshei.

Complementation for viability of the compounds tx/ty in complete lethal haplotypes t6, t12, tw5, tw12, tw18, tw73, twPa-1 belonging to the seven basic complementation groups was studied. In the overwhelming majority of crosses a lack of tx/ty offspring was revealed but there is also evidence of non-complete complementation of the tx/ty haplotypes, except for T/tw73XT/tw12, T/tw18XT/t12, T/tw73XT/tw18 crosses in which the level of complementation for viability exceeds 100%. The maternal effect for compound variability was significantly revealed in 9 out of the 19 matings. In addition, reciprocal matings of heterozygotes T/txXT/ty were tested for fertility. In two cases, the maternal effect was also revealed for this character. Comparison of data on viability of the compounds and the fertility of the original strains gives grounds to believe that the tx/ty haplotypes are not completely recessive and partially manifest themselves in the heterozygotes, decreasing fertility in a number of matings. In some cases, these t-haplotypes yield an effect, close to negative complementation, which may be associated with the interaction of the proteins of t-haplotypes.