The Significance of a Multilocus Analysis for Assessing the Biodiversity of the Romanov Sheep Breed in a Comparative Aspect.

The Romanov breed was evaluated using immunological and genetic markers. The seven blood group systems were characterized with a greater accuracy than in previous works on sheep in the Russian Federation, and were compared to eight ruminant species. Unlike other breeds, Romanov sheep shows a higher frequency of HBA than HBB alleles. There are 3-4 genotypes at the transferrin locus whereas in other breeds 6-11 genotypes have been found. At the albumin locus, the majority of the identified genotypes were heterozygotes, unlike in the other breeds studied. In the prealbumin locus, the Romanov breed was the only one where all the genotypes were heterozygous. We speculate that polymorphism at two loci (BMP-15 and BMPR1B) could effect on the high ovulation rates of Romanov sheep. Based on different genetic markers, the prevalence of heterozygotes in the Romanov sheep could determine their higher viability. A cluster analysis showed the close proximity of 12 populations of the Romanov breed, as the breeding stock come from the Yaroslavl region.

A SNP in the HSP90AA1 gene 5' flanking region is associated with the adaptation to differential thermal conditions in the ovine species.

Molecular chaperones have long been understood to be preferentially transcribed in response to multiple perturbations of the cellular homeostasis. In this study, several polymorphisms in the gene encoding the inducible form of the cytoplasmic Hsp90 (HSP90AA1) were addressed in 24 sheep breeds reared in different climatic regions of Europe, Africa, and Asia. Significant differences in the genotype frequencies for a C/G single nucleotide polymorphism (SNP) located at position -660 in the HSP90AA1 5'flanking region were found between the different breeds. Regression analyses reflected significant correlations (from 0.41 to 0.62) between the alternative genotypes of this polymorphism and several climatic and geographic variables characteristic of the regions where these breeds are reared. Real-time analysis revealed that animals bearing the CC(-660) genotype presented higher expression levels than those presenting the CG(-660) or GG(-660) in summer, but not in spring. Mutation at -660 site seems to affect HSP90AA1 transcription rates which could have important effects on the adaptation to different environmental conditions in sheep. Thus, the variability found in the genotype frequencies for the SNP at -660 in the ovine HSP90AA1 locus could be the result of the different environmental pressures occurring in the regions where these breed are maintained.