BackgroundThe red swamp crawfish, Procambarus clarkii, has become one of the most economically important cultured species in China. Currently, little is known about the gonadal development of this species. Isolation and characterization of genes are an initial step towards understanding gonadal development of P. clarkii.ResultsUsing the 454 pyrosequencing technology, we obtained a total of 1,134,993 high quality sequence reads from the crawfish testis and ovary libraries. We aimed to identify different genes with a potential role in gonad development. The assembly formed into 22,652 isotigs, distributed by GO analysis across 55 categories in the three ontologies, ‘molecular function’, ‘cellular component’, and ‘biological processes’. Comparative transcript analysis showed that 1,720 isotigs in the ovary were up-regulated and 2138 isotigs were down-regulated. Several gonad development related genes, such as vitellogenin, cyclin B, cyclin-dependent kinases 2, Dmc1 and ubiquitin were identified. Quantitative real-time PCR verified the expression profiles of 14 differentially expressed genes, and confirmed the reliability of the 454 pyrosequencing.ConclusionsOur findings provide an archive for future research on gonadal development at a molecular level in P. clarkii and other crustacean. This data will be helpful to develop new ideas for artificial regulation of the reproductive process in crawfish aquaculture.

We sequenced and characterized the complete mitochondrial genome of Channa argus, Channa maculata and their hybrid [C. maculata (♀) and C. argus (♂)]. All the three mitochondrial genomes contained the typical complement of 13 protein-coding genes, 22 transfer RNAs (tRNAs), 2 ribosomal RNAs (rRNAs) and 1 control region. The entire mitochondrial DNA (mtDNA) molecule of C. maculata was 16,559 bp long while the complete mtDNA molecule of C. argus and hybrid snakehead fish was 16,558 bp long. This is the first report on the complete mitogenome sequence of C. maculata and hybrid snakehead fish.

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