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There are significant differences in clinical characteristics between chronic hepatitis B virus infected (CHB) child and adult patients. Viral quasispecies characteristics are associated with its pathogenic properties. For hepatitis B virus (HBV), its core region is the main immune recognition region for its enriched epitopes. In our study, we discuss the quasispecies characteristics and positive selection within core gene within chronic HBV infected child and adult patients. By analyzing 170 core gene sequences from child CHB patients and 121 core genes sequences from adult CHB patients, quasispecies characteristics were described by sequence complexity, diversity, non-synonymous substitution ratio (dN) and synonymous substitution ratios (dS). In addition, positive selection sites were also determined by bioinformatics tools. Then, all these parameters were compared between child and adult CHB patient groups. Compared with child patients, adult patients with CHB showed distinct quasispecies characteristics within the core region, had a higher sequence complexity and diversity and more positive selection sites, suggesting that the adult CHB patients had a higher immune selection pressure on the HBV core gene. Reduced selection pressure on the HBV core gene in hepatitis B e antigen (HBeAg)-positive CHB patients than HBeAg negative CHB patients were observed in both adult and child patient groups. The majority of the screened positive selection sites lay within human leukocyte antigens (HLA)-restricted epitopes. In conclusion, this study analyzed the quasispecies characteristics discrepancy between child and adult patients with CHB, and revealed the possible reason for the distinct clinical characteristics in the perspective of population genetics.

As one of the closest living invertebrate relatives of vertebrates, amphioxus (subphylum Cephalochordata) occupies a key position in animal evolution and is becoming the best available proxy and model animal for studying the last common ancestor of all chordates, especially vertebrates. As long-term continuous culturing of amphioxus in laboratory became reliable, for pushing this animal to be a more successful model system, whole-genome sequencing of one or more species derived from this branch will be another urgent issue needed to address. In the present study, we described the construction and characterization of a bacterial artificial chromosome (BAC) library, using a single individual of Chinese amphioxus (Branchiostoma belcheri). High quality genomic DNA extracted from the spermary was partially digested with EcoRand EcoRmethylase. Desirable DNA fragments were isolated by pulsed field gel electrophoresis (PFGE), ligated to linearized and phosphorylased carrier pCC1BAC, and then transformed to Escherichia coli EPI300. The constructed library consists of 44 706 clones with the average insert fragment size around 80 kb as estimated by PFGE. The representation of the library is about 9 equivalents to the amhioxus genome. These results indicate that the BAC library will be useful for functional genomic studies and facilitate the whole-genome sequencing of Chinese amphioxus.

We report the generation of Ayu17-449 gene knockout mice in an effort to facilitate studies of its function during mouse development, A special gene trapping vector was transfected into mouse ES cells. The clone with the trapped gene trap was identified by 5' RACE and Southern blot analysis. Ayu17-449 trapped mice were then generated by using this ES clone. In addition, the expression of Ayu17-449 in this mutant line was analyzed with Northern blot. Results showed that in these mutant mice, the trapping vector was located upstream of the Ayu17-449 initiation site, and as a result, the transcription of Ayu17-449 gene was inhibited. Ayu17-449 trapped mice are a useful tool for the analysis of Ayu17-449 gene function in mouse development.

With more and more genome have been completely sequenced, scientists find the Partial Rule 2 (PR2) in entire single strand that A approximately equal to T, G approximately equal to C. But from the scope of thousands to hundreds of thousand bases, A not = T, G not = C. From the view of math, if the mutational rate of one strand is equal to others, it could be proved that A approximately equal to T, G approximately equal to C, but from the view of experience, that premise doesn't exist, so the solution of the problem needs the deeply combination of biology and math.

The HLA-DRB1 gene polymorphism in Lahu ethnic of Yunnan, China was the first time investigated using high resolution PCR-SBT method, which is based on sequences of HLA-DRB1 Intron 1 and Intron 2 and with our improvement. From 55 individuals of Lahu ethnic 16 DRB1 alleles were detected. The three most common alleles were HLA-DRB1 * 12021(30.909%), 09012(15.455%), 15011(13.636%), and they covered 60% of the total alleles detected from Lahu ethnic.HLA-DRB1 * 1413, * 11081, * 1312, * 1418, * 1504 were the first time detected in the Chinese, and were very rare in worldwide ethnic groups. With comparison of HLA-DRB1 gene frequencies between various ethnic groups we analyzed the characteristics of HLA-DRB1 gene distribution in worldwide populations,and constructed the phylogenetic tree by Neighbor-joining method and Nei measure of genetic distance. The result showed Lahu ethnic obviously belong to the Chinese South ethnic groups and can't trace its origin from northern groups with the HLA-DRB1 genetic data. The preliminary explanations about the contradiction were given in this paper.