Variation of HLA class II genes in the Nganasan and Ket, two aboriginal Siberian populations.

Allelic frequencies at the three most polymorphic loci of the HLA class II region (DRB1, DQA1 and DQB1) were determined in the Nganasan and Ket, the remnants of the two most ancient groups in the Lower Yenisey River/Taimyr Peninsula region in northern Siberia. By single-stranded conformational polymorphism typing, verified by sequencing, 19 HLA-DRB1-DQA1-DQB1 haplotypes and 15 HLA-DRB1, seven DQA1 and 11 DQB1 alleles were found. The most frequent alleles were DRB1*1301 (23.5%), DQA1*0103 (29.4%), *0501/03/05 (29.4%), and DQB1*0301/09 (32.4%) in the Ket, and DRB1*0901 (25%), DQA1*0301 (39.6%), and DQB1*0301/09 (37.5%) in the Nganasan. The distribution patterns and comprehensive phylogenic analysis based on the haplotype frequencies of 17 Siberian populations suggest that the founders of both the Ket and the Nganasan came from Palaeolithic populations in the Altai-Sayan Upland.

Phylogeny of antigen-processing enzymes: cathepsins of a cephalochordate, an agnathan and a bony fish.

Cathepsins are enzymes that have been cleaving peptide bonds of lysosomal proteins probably since lysosomes appeared in early eucaryotes. When the adaptive system emerged in gnathostomes, cathepsins were recruited to produce peptides for loading onto the major histocompatibility complex class II molecules and for degrading the class II-associated invariant chain just before the loading. The circumstances under which this recruitment took place are unclear because the knowledge about vertebrate cathepsins is limited largely to mammals. To shed light on the recruitment, 10 amphioxus, one lamprey and one cichlid fish cathepsin cDNA clone were characterized and analysed phylogenetically. Disregarding cathepsin O, whose phylogenetic position is uncertain, the analysis confirms the existence of two old lines of descent, the B and the L lineages of cathepsins, which diverged from each other early in the evolution of eucaryotes. The B lineage encompasses cathepsins B, C and Z (X). The L lineage splits off sublineages encompassing cathepsins F and W before the plant-animal separation and cathepsin H early in the evolution of the metazoa. The remaining cathepsins belonging to the L lineage diverged from one another during the evolution of vertebrates: S, K and L before the emergence of bony fishes, and the group of rodent placentally expressed cathepsins [J (P), M, Q, R, 3, 6, 7 and 8] as well as the testis/ova-expressed cathepsins (testins) probably after the divergence of rodents from primates. The part possibly played by the adaptive immune system in some of these divergences is discussed.

[Genetic history of Aleuts of the Komandor islands from results of analyzing variability of class II HLA genes]. / Geneticheskaia istoriia aleutov komandorskikh ostrovov po rezul'tatam analiza izmenchivosti HLA-genov II klassa.

Variability of the HLA class II genes (alleles of the DRB1, DQA1, and DQB1 loci) was investigated in a sample of Aleuts of the Commanders (n = 31), whose ancestors inhabited the Commander Islands for many thousand years. Among 19 haplotypes revealed in Aleuts of the Commanders, at most eight were inherited from the native inhabitants of the Commander Islands. Five of these haplotypes (DRB1*0401-DQA1*0301-DQB1*0301, DRB1*1401-DQA1*0101-DQB1*0503, DRB1*0802-DQA1*0401-DQB1*0402, DRB1*1101-DQA1*0501-DQB1*0301, and DRB1*1201-DQA1*0501-DQB1*0301) were typical of Beringian Mongoloids, i.e., Coastal Chukchi and Koryaks, as well as Siberian and Alaskan Eskimos. Genetic contribution of the immigrants to the genetic pool of proper Aleuts constituted about 52%. Phylogenetic analysis based on Transberingian distribution of the DRB1 allele frequencies favored the hypothesis on the common origin of Paleo-Aleuts, Paleo-Eskimos, and the Indians from the northwestern North America, whose direct ancestors survived in Beringian/southwestern Alaskan coastal refugia during the late Ice Age.