[Advances in application of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 system in stem cells research]

Gene engineering has attracted worldwide attention because of its ability of precise location of disease mutations in genome. As a new gene editing technology, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9) system is simple, fast, and accurate to operate at a specific gene site. It overcomes the long-standing problem of conventional operation. At the same time, stem cells are a good foundation for establishing disease model in vitro. Therefore, it has great significance to combine stem cells with the rapidly developing gene manipulation techniques. In this review, we mainly focus on the mechanism of CRISPR/Cas9 technology and its application in stem cell genomic editing, so as to pave the way for promoting rapid application and development of CRISPR/Cas9 technology.

Phylogeography and origin of Chinese domestic chicken

The loss of local chicken breeds as result of replacement with cosmopolitan breeds indicates the need for conservation measures to protect the future of local genetic stocks. The aim of this study is to describe the patterns of polymorphism of the hypervariable control region of mitochondrial DNA (HVR1) in domestic chicken in China's Jiangxi province to investigate genetic diversity, genetic structure and phylo-dynamics. To this end, we sequenced the mtDNA HVR1 in 231 chickens including 22 individuals which belonged to previously published sequences. A neighbor-joining tree revealed that these samples clustered into five lineages (Lineages A, B, C, E and G). The highest haplotype diversity and nucleotide diversity were both found in Anyi tile-liked gray breed. We estimated that the most recent common ancestor of the local chicken existed approximately 16 million years ago. The mismatch distribution analysis showed two major peaks at positions 4 and 9, while the neutrality test (Tajima's D = -2.19, p < 0.05) and Fu's F-statistics (-8.59, p < 0.05) revealed a significant departure from the neutrality assumption. These results support the idea that domestication of chickens facilitated population increases. Results of a global AMOVA indicated that there was no obvious geographic structure among the local chicken breeds analyzed in this study. The data obtained in this study will assist future conservation management of local breeds and also reveals intriguing implications for the history of human population movements and commerce.