Mouse genome contains two major families of short interspersed repeats in more than 10(5) copies scattered throughout the whole genome. They are referred to as B1 and B2 sequences since they were first isolated from the genome library by means of a dsRNA-B probe /1/. In this work, two copies of the B2 family were sequenced and compared with the previously sequenced B1 repeat /2/. A B2 ubiquitous repeat is ca. 190 bp long. The members of the family deviate in 3-5% of nucleotides from the consensus sequence. B2 contains regions of homology to the RNA polymerase III split promoter and to 4.5S snRNA I. Both B1 and B2 contain regions which resemble junctions between exons and introns. In contrast to B1, B2 does not contain apparent homologies to papova viral replication origins and a human Alu sequence. One side of the B2 repeat is represented by a very AT-rich sequence (ca. 30 bp long) followed with an oligo (dA) stretch 10-15 nucleotides long. This region of the repeat is the most variable one. The whole unit is flanked with 15-16 bp direct repeats different in sequenced copies of B2. The same is true of some copies of the B1 family. The properties of B1 and B2 repeats suggest that they may represent a novel class of transposon-like elements in eukaryotic genome. A possible role of B-type repeats in genome reorganization, DNA replication and pre-mRNA processing is discussed.

Three copies of a highly repetitive DNA sequence B1 which is complementary to the most abundant class of mouse fold-back RNA have been cloned in pBR322 plasmid and sequenced by the method of Maxam and Gilbert. All the three have a length of about 130 base pairs and are very similar in their base sequence. The deviation from the average sequence is equal to 4% and the overall mismatch between each two is not higher than 8%. One of the recombinant clones used contained two copies of B1 oriented in the same direction. All of the B1 copies are flanked with sequences which possess nonidentical but very similar structure. They consist of a number of AmCn blocks (where m varies from 2 to 8 and n equals 1-2). These peculiar sequences in all cases are separated from B1 by non-homologous DNA stretches of 2-8 residues. In one case, a long polypurine stretch is located next to such a block. It consists of 74 residues most of which represent a reiteration of the basic sequence AAAAG. We have found two regions within the B1 sequence which are homologous to the intron-exon junctions, especially to those present in the large intron of the mouse beta-globin gene. It may indicate the involvement of the B1 sequence in pre-mRNA splicing.

The role of genes in the expression of aggression and masculinity traits in humans has been a focus of recent behavioral genetic studies. This is the first study on the variation in aggression, the digit ratio (the ratio between the second and the fourth digits, 2D:4D), the directional asymmetry in 2D:4D (D(R-L)) and polymorphisms of the AR, DRD4, and 5-HTTL genes in simple hunter-gatherers, namely the Hadza of Tanzania (142 adult men). The distribution of AR, DRD4E3, and 5-HTTLPR genotypes and allele frequencies in Hadza was compared to other African populations on which the data were available. Hadza and Ariaal differed significantly in the distributions of frequencies of AR alleles with different numbers of CAG repeats. Hadza population was similar to other African populations in the distribution of allelic frequencies of the DRD4E3 locus, and to Afro-Americans in the distribution of allelic types of the 5-HTTLPR locus. We found no influence of AR gene on the right hand 2D:4D ratio, D(R-L), and any of aggression subscales of the Buss-Perry Aggression Questionnaire (AQ). Although, a weak positive correlation between CAG repeats and the left hand 2D:4D was found. The multiple regression analysis with digit ratios, D(R-L) and aggression subscales of AQ as dependent variables and the three gene candidates (AR, DRD4E3, and 5-HTTLPR) as independent variables revealed the following: men with lower number of CAG repeats had significantly lower left hand 2D:4D ratio; men with higher numbers of 48-bp unit copies in exon 3 of a VNTR polymorphism in the DRD4 gene had significantly lower digit ratios on both hands; no effect of the 5-HTTLPR gene on either the digit ratio or aggressive behavior. These findings demonstrate the complexity of gene effects on digit ratios and aggression and call for simultaneous analysis of more candidate genes. It is noteworthy that these results were obtained for a human population that is still practicing foraging and has been subjected to a high selective pressure due to harsh environments and practically has no access to modern medical care. Hadza are highly egalitarian, and their culture does not favor persons with a dominant or aggressive behavior. It is still to be found to what extent the relationships observed in this study are similar to those in other human populations.

DNA preparations from about hundred randomly selected clones containing mouse DNA fragments were screened for the existence of sequences complementary to long double-stranded regions of pre-mRNA able to snap back after melting (dsRNA-B). Many clones containing such sequences were found. The cloned sequences can be subdivided into three groups: (1) those complementary to about a half (at least to 30-40%) of the total dsRNA, designated as sequences B1; (2) those complementary to a part of sequence B1; and (3) sequences complementary to about a quarter (at least to 15%) of the total dsRNA referred to as sequence B2. The size of DNA sequence complementary to dsRNA is about 400 base pairs. Melting experiments with hybrids show that the members of B1 family are very similar if not identical, while the divergence among B2 sequences is higher, but still the number of substitutions does not exceed 9% of bases. Thus, the major part of dsRNA-B consists of a small number of highly abundant sequences as was suggested earlier on the basis of renaturation kinetics /1-3/. Sequences B1 and B2 are represented by many copies in the mouse genome and in pre-mRNA, and many of them probably do not form hairpin-like structures.

Partial sequences of mitochondrial genes nad1 (316 bp) and cox1 (429 bp) were analyzed to estimate the variability of the liver fluke samples collected in 20 localities in Russia, Belarus, Ukraine, Bulgaria, Armenia, Azerbaijan, Georgia, Turkey, Turkmenistan, and China. The sequences had 4.1% (nad1) and 2.3% (cox1) of variable sites, and 13 and 10 haplotypes were identified among nad1 and cox1 genes, respectively. Spatial analysis of genetic and nucleotide diversity indicated little or no structuring of genetic variation between hosts or regions. The analysis of distribution of both separate and combined (nad1 + cox1) haplotypes revealed the existence of 2 well-defined lineages with 2 main haplotypes and a number of shared divergent haplotypes. Our study showed that the first lineage included the main N1-C1 haplotype, which was found in Australia, China, Georgia, Turkey, Armenia, Azerbaijan, and in all European populations (from Russia, Belarus, Ukraine, Bulgaria). The second lineage was found in all European populations and in populations from Armenia and Azerbaijan. It was suggested that one of the lineages (I) has an Asian origin. The possible source of mtDNA variability and associations between lineage divergence of parasite and its definitive hosts (cattle and sheep) are discussed.

Molecular study of mitochondrial and nuclear genes and cytogenetic analysis were performed to examine possible patterns of speciation in the diverse Lophuromys flavopunctatus species complex of Ethiopia. Phylogenetic analysis of mtDNA data resulted in an unresolved bush of ten deeply diverged haplotype groups corresponding to potential species either well supported by various types of character or 'cryptic'. The cytogenetic analysis showed representatives of five of these mtDNA lineages to share an identical karyotype (2 n = 70, NFa = 84), that has not been found previously in Ethiopia. One of them, L. cf. sikapusi , being a member of the L. flavopunctatus species complex, demonstrates remarkable morphological similarity to representatives of another species complex, L. sikapusi s.l ., which might be considered as a result of convergent evolution in analogous environments. Analysis of RAPD data suggests that at least two mtDNA types might have been subject to interspecific transfer due to hybridization. In the case of two sympatric haplotypes of L. brunneus we may assume that the contemporary pattern of variation between them can be explained by relatively recent hybridization with another distinct species, L. flavopunctatus . The formation of two groups belonging to distinct mitochondrial lineages within northern populations could be associated with more complex processes including ancient hybridization.

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