Genome-wide identification and tissue expression analysis of the somatostatin family genes in Trachinotus ovatus

【Objective】To study the type of somatostatin（SST）family genes and their tissue expressions in Trachinotus ovatus，and to lay the foundation for further research on the role of SST family genes in the growth and development of T. ovatus.【Method】HMMER 3.1 was used to identify somatostatin family genes from the whole genome data of T. ovatus，and then Pfam，Smart and NCBI CDD were used to confirm the searched genes belong to SST gene family. Subbioinformatic analysis was performed using online software such as ProtParam and PSORT. The expression of SST family genes in different tissues of T. ovatus were quantitatively analyzed by real-time fluorescence quantitative PCR.【Result】 Four SST family genes（SST1，SST3，SST5 and SST6）were identified from the whole genome of T. ovatus，encoding 122，127，106 and 110 amino acids，respectively. The molecular weight of the corresponding coding protein ranged from 12249.3 to 14316.1 Da，theoretical isoelectric points（pI）ranging from 6.51 to 7.43，and the four gene products were all located outside the cell. The structures of the four SST genes were similar，including two exons and one intron. SST1 and SST3 genes were located on chromosome 7，while SST6 and SST5 genes were located on chromosome 8 and 23，respectively. The average similarity of the four SST amino acid sequences was 33.42%，among which the similarity between SST5 and SST6 was the highest（39.78%），and the similarity between SST3 and SST5 was the lowest（28.16%）. The expression levels of the SST family genes were different in brain，stomach，gonad and muscle of T. ovatus. Among them， the expressions of SST1，SST3 and SST6 genes were significantly higher in brain tissue（P<0.05，the same below），while SST5 was significantly highly expressed in gonad and muscle tissues. In addition，the expression of SST3，SST5 and SST6 genes in the ovary were significantly higher than in the testis.【Conclusion】Four SST family genes（SST1，SST3，SST5 and SST6）are identified from the genome of T. ovatus and the expression and distribution are tissue-specific and speciesspecific. SST genes may mediate a variety of physiological functions in neuroregulation，gonadal development，and sexual dimorphism of T. ovatus，and the function of SST genes in different species may differ.