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. 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. 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.

/pdf/a-draft-genome-of-the-striped-catfish-pangasianodon-3j1dpvh3mm.pdf

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

https://onlinelibrary.wiley.com/doi/pdf/10.1111/raq.12554

A review on sox genes in fish

The sox family is assumed to be responsible for a number of developmental systems. Genome sequencing technology makes it possible to scan sox genes and conduct characteristic analyses of different species. In fish, full characterisation of sox genes at the genome-wide level has been reported for pufferfish Takifugu rubripes, medaka Oryzias latipes, tilapia Oreochromis niloticus and channel catfish Ictalurus punctatus. However, no systematic investigation of the sox family in sturgeons (Acipenseridae) has been reported to date. This study conducted genome-wide identification of the sox genes in the Chinese sturgeon Acipenser sinensis and profiled their tissue distribution between male and female individuals. In total, 19 sox genes were identified, including soxb1, b2, c, d, e, f and h, in the Chinese sturgeon. Genomic structure analysis indicated relatively conserved exon-intron structures in each sox group and phylogenetic analysis supported the previous classification of the sox family. Most of the sox genes showed a tissue-specific expression pattern, indicating the possible involvement of Chinese sturgeon sox genes at different developmental processes such as cardiac and gonadal development. This study provides a comprehensive resource of Chinese sturgeon sox genes and enables a better understanding of the evolution and function of the sox family.

https://onlinelibrary.wiley.com/doi/epdf/10.1111/jfb.14199

Genome-wide analysis of the Chinese sturgeon sox gene family: identification, characterisation and expression profiles of different tissues.

Genome-wide investigation of Dmrt gene family in large yellow croaker (Larimichthys crocea).

Members of the Sox gene family play crucial roles during reproduction and development, but their genome-wide identification has not yet been performed in large yellow croaker, Larimichthys crocea. In this study, a total of 26 members of the Sox gene family were identified from the genome of large yellow croaker and classified into seven subgroups based on the conserved HMG-box domain they contain. Among the identified Sox gene family members, eight belonged to the SoxB subgroup (five in B1 and three in B2), four belonged to the SoxC subgroup, four belonged to the SoxD subgroup, six belonged to the SoxE subgroup, three belonged to the SoxF subgroup, and one belonged to the SoxK subgroup. During evolution, members of the SoxE subgroup (Sox8, Sox9, Sox10), Sox1, Sox4, Sox6, and Sox11 evolved into two copies, which may be a result of teleost-specific whole-genome duplication. Sox genes were distributed unevenly across 15 chromosomes. The number of introns in large yellow croaker Sox genes varied from 0 to 14. Results of the expression profile during embryogenesis revealed that most of the members of the Sox gene family had lower expression, except several Sox genes, and expression patterns also differed among each Sox gene group and duplicated gene. This study systematically characterized and analyzed the Sox gene family in large yellow croaker and provided new insights into its function during embryogenesis.

Genome-Wide Identification and Expression Profile of the Sox Gene Family During Embryo Development in Large Yellow Croaker, Larimichthys crocea

Genome-wide identification, phylogeny and expressional profile of the Sox gene family in channel catfish (Ictalurus punctatus)

The effect of a polystyrene nanoplastic on the intestinal microbes and oxidative stress defense of the freshwater crayfish, Procambarus clarkii.

Full-Length Transcriptome of Red Swamp Crayfish Hepatopancreas Reveals Candidate Genes in Hif-1 and Antioxidant Pathways in Response to Hypoxia-Reoxygenation

In China, channel catfish (Ictalurus punctatus) is an important aquaculture species; however, haemorrhagic disease (Aeromonas hydrophila induced disease) in these fish has caused tremendous economic loss due to high morbidity and mass mortality in the breeding industry. The role of cortisol in bacterial diseases, particularly in the acute phase, remains unclear. In this study, liver transcriptome (RNA-seq) and chromatin accessibility (ATAC-seq) analyses were employed to investigate the early functional role of cortisol in Aeromonas hydrophila-stimulated responses. Our experiments confirmed that A. hydrophila infection can initially significantly increase serum cortisol levels at 1 h after infection. At this time point, the increased serum cortisol levels can significantly regulate A. hydrophila-regulated genes by affecting both transcriptome and chromatin accessibility. Cross-analysis of RNA-seq and ATAC-seq revealed that a certain gene group (92 target_DEGs) was regulated at an early time point by cortisol. KEGG enrichment analysis revealed that the top three pathways according to target_DEGs were cancer, glutathione metabolism, and the Notch signalling pathway. The protein-protein interaction analysis of target_DEGs revealed that they may be primarily involved in cell proliferation, CD8+ T cell function, glutathione synthesis, and activation of the NF-κB signalling pathway. This suggests that after the emergence of immune stress, the early regulation of cortisol is positive against the immune response. It is possible that in this situation, the animal is attempting to avoid dangerous situations and risks and then cope with the imbalance produced by the stressor to ultimately restore homeostasis. Our results will contribute to future research on fish and provide valuable insight regarding the mechanism of immune regulation by cortisol and the study of bacterial haemorrhagic disease in channel catfish.

/pdf/the-early-function-of-cortisol-in-liver-during-aeromonas-2rmsbeeb.pdf

Mengling Sun

Papers

Genome-wide identification, phylogeny and expressional profile of the Sox gene family in channel catfish (Ictalurus punctatus)

The effect of a polystyrene nanoplastic on the intestinal microbes and oxidative stress defense of the freshwater crayfish, Procambarus clarkii.

Full-Length Transcriptome of Red Swamp Crayfish Hepatopancreas Reveals Candidate Genes in Hif-1 and Antioxidant Pathways in Response to Hypoxia-Reoxygenation

The early function of cortisol in liver during Aeromonas hydrophila infection: Dynamics of the transcriptome and accessible chromatin landscapes