[Comparative Analysis of Polymorphisms of the Serotonin Receptor Genes HTR1A, HTR2A, and HTR1B in Hadza and Datoga Males].

The distribution of the allele and genotype frequencies of polymorphic loci of serotonin receptor genes (HTR1A, rs6295; HTR2A, rs6311; HTR1B, rs6296) in Hadza (n = 197) and Datoga males (n = 230) living in Tanzania was determined. It was shown that the populations significantly differ by the frequencies of alleles and genotypes of the rs6295 locus of the HTR1A gene. The G-allele (0.779) and the genotype G/G (0.590), which are markers of increased risk of suicidal and impulsive behavior, respectively, are revealed in Hadza with high frequency. It was found that the frequency of homozygous G/G of the rs6296 locus of the HTR1B gene, which is a marker of increased risk of outward directed aggression, is higher in Datoga (0.563) than in Hadza (0.457). The allele and genotype frequencies of the rs6311 locus of the HTR2A gene do not differ among the Hadza and Datoga males. The data on the distribution of allele and genotype frequencies of the HTR1A, HTR2A, and HTR1B genes can be used to determine the associations of the identified markers with various forms of human aggressive behavior.

[The 3'-UTR polymorphism of dopamine transporter gene in hadza and datoga males].

The study of VNTR-polymorphism and the molecular struc ture of 3'-UTR of the dopamine transporter gene (DAT1/SLC6A3) was performed in hadza and datoga males. It was shown that hadza and datoga differed in allele and genotype frequencies. Allele with 9 repeats in 3'-UTR is more common in hadza as well as homozygous genotype DAT19/9. Allele with 10 repeats is more common in datoga as well as homozygous genotype DAT1 10/10. The molecular structure of the DAT alleles with 3, 8 and 12 repeats was determined for the first time. In addition it was found that DAT1 allele with 11 repeats in datoga significantly differed from previously described ones in other populations in repeats type and arrangement. We suggest that variations of the repeats num ber and type in the 3'-UTR of allelic variants may affect the dopamine transporter gene function.

[Polymorphism of 5-HTTLPR and Stin2 loci of the serotonin transporter gene in males of African ethnic populations Hadza and Datoga].

A molecular-genetic study of 5-HTTLPR and the Stin2 loci of the serotonin transporter gene (5-HTTL) in males of the African ethnic populations Hadza and Datoga, which differ in the level of culturally acceptable aggression, was carried out. The distribution of allele and genotype frequencies of these two loci was established. It was shown that the frequency distribution of genotypes and alleles among Hadza and Datoga in the examined samples is practically identical by the VNTR-polymorphism of both loci. However, the Hadza populations, as compared to Datoga, showed a significant (p = 0.006) increase in the frequency of the transcriptionally less active allele L(G) of the 5-HTTLPR locus. For the first time, the structure of the allelic variant of locus Stin2 with eight repetitions (Stin2.8) is described and established for African populations. The test for independence of the frequency distribution of the alleles of the studied loci showed highly significant linkage disequilibrium among Hadza (p << 0.001) and Datoga (p = 0.021). In analysis of the genotype combinations of two loci, it was revealed that thestudied populations differed significantly by the L(A)L(G) 10/12 genotype (p << 0.001). When combining the genotypes, no significant differences between the populations based on their expression activity were identified. We assume that the identified combined genotypes reflect the effects of similar behavioral traits for both populations.

[Molecular genetic polymorphism of androgen receptor gene (AR) in African populations of Hadza and Datoga].

The molecular genetic analysis of the polymorphic variants of the CAG repeat-containing locus of the andro- gen receptor (AR) gene was performed in the populations of Hadza and Datoga. Allele frequency distribution patterns were established. Alleles containing 20-25 repeats were the most abundant in both populations were the. The populations studied were compared with Asians (Han), white Americans, and Africans (Ariaal). Sta- tistically significant difference between populations of Hadza and Datoga in the distribution of the AR allelic variants was demonstrated.

[Evolutionary relationships between reptiles inferred from the comparison of their ITS2 sequences].

The reptile phylogeny is poorly studied, and many existing hypotheses are controversial. In this study, the ITS2 regions of 43 species of lizards, snakes, turtles, and crocodiles were cloned and sequenced in addition to eight ITS2 sequences of amphibians, reptiles, and birds already present in the database. The ITS2 of reptiles, similarly to other vertebrates, contain short conserved (consensus) regions, alternating with variable regions (DI, DII, and DIII), which are potentially capable of forming stable secondary structures. These functionally neutral rDNA regions, separating the consensus regions, are substantially different in size, as well as in the primary and secondary structure. Sequences of the ITS2 variable regions were aligned using the GeneBee Molecular Biology Server software program with subsequent automated construction of prescribed trees. The trees for all three variable regions were highly similar, enabling certain conclusions on the evolutionary history of reptiles.

[Polymorphism of the dopamine D4 receptor (DRD4) and serotonin transporter (5-HTTL) gene promoter regions in African tribes of Hadza and Datoga].

Molecular genetic analysis of the allelic variants of the DRD4 and 5-HTTL gene promoter regions was performed in African tribes of Hadza and Datoga, characterized by different levels of socially acceptable aggression. It was demonstrated that Hadza and Datoga people differed in the structural organization of one of the 5-HTTL alleles (extra long allele xL). Analysis of the allele length polymorphism of both genes showed that in the Hadza and Datoga samples examined, variation parameters, as well as the genotype and allele frequency distribution pattern were almost the same. At the same time, analysis of the SNP polymorphism at the A/G substitutions of the 5-HTTL locus revealed a substantial decrease of the active allele L(A) frequency in the population of Hadza compared to the population of Datoga (chi2 = 3.77; d.f = 1; P = 0.052).

Enhanced heterogeneity of the LR2 segment in the human ribosomal intergenic spacer.

Human ribosomal intergenic spacer (rIGS) contains in its central part two highly homologous 2 kb repeats, LR1 and LR2. In this paper, we investigate heterogeneity of the variable LR2 segment (LR2var) in the human rIGS. More than 500 LR2var copies from ten unrelated human genomes have been cloned and sequenced. Prolonged (G)n (AG)m compound microsatellite clusters with 'n' and 'm' notions fluctuating in random manner span central parts of almost all LR2var variants. Nucleotide sequences flanking the central microsatellite clusters are represented by more than 30 structural groups, with the two major (A and B) and six minor (C-H) ones. The analysis of sequencing data let us propose that the LR2var variability can be derived by various ways, including microsatellite DNA slip-strand mispairing during replication, non-equal crossover and segmental DNA exchange between LR1var and LR2var through the mechanism of gene conversion.

[Specific organization of ribosomal DNA arrays in Squamata].

A first report on structural organization of ribosomal DNA arrays in some members of the order Squamata is presented. The data obtained point to unusually small (for vertebrates) size of the rDNA repetitive unit (approximately, 10 to 15 kb) in the lizard species examined. Analysis of BAC library of Uta stansburiana (Iguania) showed that haploid genome of this lizard contained a single cluster, consisting of about ten rDNA repeats. Determination of the extent of rDNA unit repetition in some other representatives of the order Squamata, using the method of comparative real-time PCR, showed that the number of rDNA units varied from one or several dozens in Iguanina to several hundred repeats in Scincomorpha and Varonoidea. The results are discussed in terms of an ambiguous position of the family Iguania on the evolutionary trees constructed based on morphological and molecular data.

[Evolutionary divergence of the ribosomal internal transcribed spacer 2 (ITS2) in lizards].

During the pre-rRNA cleavage pathway, the excision of ITS2, a eukaryotic specific insertion, remains the most elusive processing step, even in yeast. Comparison of the ITS2 sequences in different organisms permits to reveal conservative, presumably functionally important elements as well as obtain new information about ITS2 divergence in evolution. We have cloned and sequenced the ITS2 of three lizard species, Agama caucasia (Agamidae), Darevskia armeniaca and Lacerta strigata (Lacertidae) and detected in them a set of specific and conservative structural elements employing secondary structure consensus for vertebrate ITS2. Furthermore, we have performed an alignment and comparative analysis of the ITS2 sequences for the two lizards families. It enables us to propose that modern lizard species formation in evolution was accompanied by ITS2 duplication in the rDNA of their common progenitors.

[Detection of intragenomic polymorphism in the LR2 region of human intergenic ribosomal spacer]. / Obnaruzhenie vnutrigenomnogo polimorfizma uchastka LR2 mezhgennogo ribosomnogo speisera cheloveka.

It is a common point of view today that tandem ribosomal genes are subject to concerted evolution, a process that promotes homogeneity among the many copies through the mechanisms of unequal homologous exchange and gene conversion. These mechanisms can lead to opposite results: they can correct and eliminate new variants and they also can promote the spread of new gene variants throughout individual gene clusters among homologous and non homologous chromosomes. A number of experiments performed to decide which of these mechanisms is more important have yielded contradictory answers to this question. In this work we have cloned and partially sequenced 36 PCR-amplified copies of the human rIGS segment 22763-23523 apart from the transcription start point, obtained from the individual genome. This segment is enriched by (G)n and (AG)n clusters and enters into 2kb LR2 element of the human rIGS. Comparative analysis showed that absolutely identical sequences are absent among 36 inserts sequenced. The 26 clones differed only on a number of repeating elements in the paralogous (G)n and (AG)n clusters. The last ten clones differed not only on a number of cluster repeating elements, but contained insertions and deletions of distinct sizes, which do not correspond to the human rIGS polymorphism variants described earlier.

PCR-generated artificial ribosomal DNAs from premature termination at Alu sequences.

PCR-amplified product may sometimes not correlate with a DNA state in vivo due to formation of recombinant molecules. Here we show that recombinant product can form in vitro on amplifying the region upstream of the rRNA transcription start point in human ribosomal intergenic spacer. These results provide the first information concerning definite Alu sites where premature polymerase termination occurs.

[Cloning and comparative characterization of the rIGS regulatory regions in humans and the pygmy chimpanzee Pan paniscus]. / Klonirovanie i sravnitel'naia kharakteristika uchastkov reguliatornoi oblasti rMGS cheloveka i karlikovogo shimpanze Pan paniscus.

Investigation of randomly cloned genomic and chromosome-specific sequences of ribosomal DNA (rDNA) from different organisms show that different regions of this long repeat unit evolve at different rates. This proves to be true not only with regard to evolutionary variability of transcribed and nontranscribed intergenic (spacer) regions of rDNA. The intergenic spacer (rIGS) of human ribosomal DNA contains both highly variable and more conservative regions with putative regulatory functions. In the present study a comparative analysis of some segments of the rIGS pre-promoter (regulatory) region in human and pygmy chimpanzee (Pan paniscus) was carried out. For these purposes, the corresponding DNA fragments were amplified in PCR with oligonucleotide primers specific to human rIGS and sequenced. Our results show that at the background of substantial structural similarity of these regions in man and chimpanzee, i.e., the presence of highly homologous sequences and similar repetitive units, there are substantial differences between them. These differences are associated with point mutations, insertions, deletions, and complex structural rearrangements.