The diversity of major histocompatibility complex class II DRB1 gene in sheep breeds from Xinjiang, China.

Exon 2 of the ovine leukocyte antigen OLA-DRB1 locus was examined in sheep from the Xinjiang Karakul Ram and Bashibai populations, and three generations of hybrids were derived from a cross between Bashibai and Altai Argali wild sheep. This identified 12 novel alleles and 30 previously reported alleles. A neighbor-joining tree of the amino acid sequences of these 42 alleles revealed allelic clusters shared across the study populations. There were significant differences in allelic frequency between Karakul Ram and Bashibai sheep. DRB1*K18cC was the most frequent allele in Kararul Ram with a frequency of 21.2%, while DRB1*2F10c8 (13.2%) and DRB1*0803 (13.2%) were the most frequent alleles found in Bashibai sheep; the alleles DRB1*2F16c2, DRB1*1601, and DRB1*0803 occurred most frequently in F1, F2, and F3 populations, with frequencies of 17.6%, 14.3%, and 20%, respectively. Although many alleles were shared by Bashibai and hybrid sheep, some alleles differed between them, especially in the F1 generation of the Bashibai × Altai Argali cross. The hybrid-specific alleles indicated the introgression of Altai Argali alleles into hybrid flocks. A population tree based on the OLA-DRB1 allelic frequency in each population indicated that the Bashibai sheep and three hybrid populations were similar, with Karakul Ram being genetically distinct.

Interactions between rare-earth ions and DNA of Bashibai sheep.

The interaction between rare-earth ions and DNA from Bashibai sheep was studied by microcalorimetry and electrochemistry. The DNA chain was found to have four to five binding sites for rare-earth ions. The binding affinity was about 10⁻5-10⁻6 M. It was also found that smaller ions caused more heat to be released in the process of binding and bound more readily to the nucleic acid chain. This is attributed to the enhanced ability of polarization of smaller ions and reduced steric hindrance compared to larger ions. The electrochemistry results show that rare-earth ions could be inserted into the DNA helix, producing a new complex with electrochemically active groups. The rare-earth ions and DNA complex reached equilibrium after a 90-min incubation at room temperature.