Draft genome of the protandrous Chinese black porgy, Acanthopagrus schlegelii.

Background: As one of the most popular and valuable commercial marine fishes in China and East Asian countries, the Chinese black porgy (Acanthopagrus schlegelii), also known as the blackhead seabream, has some attractive characteristics such as fast growth rate, good meat quality, resistance to diseases, and excellent adaptability to various environments. Furthermore, the black porgy is a good model for investigating sex changes in fish due to its protandrous hermaphroditism. Here, we obtained a high-quality genome assembly of this interesting teleost species and performed a genomic survey on potential genes associated with the sex-change phenomenon. Findings: We generated 175.4 gigabases (Gb) of clean sequence reads using a whole-genome shotgun sequencing strategy. The final genome assembly is approximately 688.1 megabases (Mb), accounting for 93% of the estimated genome size (739.6 Mb). The achieved scaffold N50 is 7.6 Mb, reaching a relatively high level among sequenced fish species. We identified 19 465 protein-coding genes, which had an average transcript length of 17.3 kb. By performing a comparative genomic analysis, we found 3 types of genes potentially associated with sex change, which are useful for studying the genetic basis of the protandrous hermaphroditism. Conclusions: We provide a draft genome assembly of the Chinese black porgy and discuss the potential genetic mechanisms of sex change. These data are also an important resource for studying the biology and for facilitating breeding of this economically important fish.

[Influence of age on the effectiveness of revascularization in immature permanent teeth].

PURPOSE: To evaluate the effect of age on the potential of dental pulp regeneration in young permanent teeth with periapical periodontitis. METHODS: A total of 30 mandibular premolars from 9-18 years old patients with pulp necrosis were divided into 2 groups, group A (younger age group): 9-13 years old, and group B (older age group): 14-18 years old. Revascularization procedures were performed for all patients. Follow-up was done for up to 18 months. Standardized radiographs of cone-beam CT (CBCT) were digitally evaluated for increase in root length and thickness. The data were analyzed by nonparametric two sample rank sum test using SPSS13.0 software package. RESULTS: After 18 months of follow-up, the clinical symptoms of the two groups disappeared. The cure rate of group A was significantly higher than that of group B (P=0.003). Radiographic analysis showed that the root length and root canal wall thickness in group A was significantly greater than those in group B (P<0.05). CONCLUSIONS: Root canal revascularization can be widely used in the treatment of dental pulp necrosis in young permanent teeth. The closer the age is to the eruption time, the higher the potential of dental pulp regeneration, and the more suitable for root canal revascularization.