A draft genome of the striped catfish, Pangasianodon hypophthalmus, for comparative analysis of genes relevant to development and a resource for aquaculture improvement.

BACKGROUND: The striped catfish, Pangasianodon hypophthalmus, is a freshwater and benthopelagic fish common in the Mekong River delta. Catfish constitute a valuable source of dietary protein. Therefore, they are cultured worldwide, and P. hypophthalmus is a food staple in the Mekong area. However, genetic information about the culture stock, is unavailable for breeding improvement, although genetics of the channel catfish, Ictalurus punctatus, has been reported. To acquire genome sequence data as a useful resource for marker-assisted breeding, we decoded a draft genome of P. hypophthalmus and performed comparative analyses. RESULTS: Using the Illumina platform, we obtained both nuclear and mitochondrial DNA sequences. Molecular phylogeny using the mitochondrial genome confirmed that P. hypophthalmus is a member of the family Pangasiidae and is nested within a clade including the families Cranoglanididae and Ictaluridae. The nuclear genome was estimated at approximately 700 Mb, assembled into 568 scaffolds with an N50 of 14.29 Mbp, and was estimated to contain ~ 28,600 protein-coding genes, comparable to those of channel catfish and zebrafish. Interestingly, zebrafish produce gadusol, but genes for biosynthesis of this sunscreen compound have been lost from catfish genomes. The differences in gene contents between these two catfishes were found in genes for vitamin D-binding protein and cytosolic phospholipase A2, which have lost only in channel catfish. The Hox cluster in catfish genomes comprised seven paralogous groups, similar to that of zebrafish, and comparative analysis clarified catfish lineage-specific losses of A5a, B10a, and A11a. Genes for insulin-like growth factor (IGF) signaling were conserved between the two catfish genomes. In addition to identification of MHC class I and sex determination-related gene loci, the hypothetical chromosomes by comparison with the channel catfish demonstrated the usefulness of the striped catfish genome as a marker resource. CONCLUSIONS: We developed genomic resources for the striped catfish. Possible conservation of genes for development and marker candidates were confirmed by comparing the assembled genome to that of a model fish, Danio rerio, and to channel catfish. Since the catfish genomic constituent resembles that of zebrafish, it is likely that zebrafish data for gene functions is applicable to striped catfish as well.

In silico studies for the interaction of tumor necrosis factor-alpha (TNF-α) with different saponins from Vietnamese ginseng (Panax vietnamesis).

Tumor necrosis factor-alpha (TNF-α) is a cytokine that plays an important role in inflammatory process and tumor development. Recent studies demonstrate that triterpene saponins from Vietnamese ginseng are efficient inhibitors of TNF-α. But the interactions between TNF-α and the saponins are still unclear. In this study, molecular docking and molecular dynamics simulations of TNF-α with three different triterpene saponins (majonoside R2, vina-ginsenoside R1 and vina-ginsenoside R2) were performed to evaluate their binding ability. Our results showed that the triterpene saponins have a good binding affinity with protein TNF-α. The saponins were docked to the pore at the top of the "bell" or "cone" shaped TNF-α trimer and the complexes were structurally stable during 100 ns molecular dynamics simulation. The predicted binding sites would help to subsequently investigate the inhibitory mechanism of triterpene saponins.