Xie Zhuang

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.

Study on the origin and taxonomic status of yak (Poephagus) using cytochrome b gene of mitochondrial DNA

There still exists a remarkable difference on the yak’s taxonomic status in Bovinae. Primers designed according to the mitochondrial gene sequences of Bos taurus reported were used to amplify and sequence the yak’s cytochrome b gene, and the whole sequence of cytochrome b gene was finally obtained. Using Ovis aries as outgroup taxa, the phylogeny about the representative species of Bovinae was analyzed. Results showed that among the different species, the ratio of transition/transversion (Ts/Tv) of Cytochrome b gene was 4.9, suggesting that the mutation was not saturation. The percentage nucleotide sequence divergence between yak and Bovinae was 8.0%–8.6%, which was higher than that of yak and Bison bison. Phylogeny analysis found that Poephagus grunniens and Poephagus mutus clustered first before gathering with Bison bison, indicating higher genetic comparability than that of Bos. The results sustained the idea that Poephagus grunniens and Poephagus mutus shared one ancestor—the primitive yak. The approximate divergence time between these two species was 0.55 million years. The data also supported the viewpoint that the yak is classified into Poephagus of Bovinae, including two species of Poephagus grunniens and Poephagus mutus.