Genomic Analysis of the Proteasome Subunit Gene Family and Their Response to High Density and Saline-Alkali Stresses in Grass Carp

Abstract

The proteasome is a highly conserved polycatalytic enzyme that is required for cellular processes and is widely present in the nucleus and cytoplasm of archaea, as well as all eukaryotes. A total of 22 members of the proteasome subunit (CiPS) gene family were identified and characterized by scanning the grass carp (Ctenopharyngodon idella) genome. These genes were classified into two subfamilies, CiPSA and CiPSB, based on phylogenetic analysis, which was consistent with the results from other species. We examined the response of this gene family to high density and saline-alkali stresses in aquaculture using publicly available transcriptome data resources. In grass carp, CiPS member transcripts were detected in all tested tissues, with the highest expression level in the head kidney and the lowest in the liver. According to transcriptome-based expression analysis, CiPS genes play a role in response to environmental stresses in grass carp, mainly in the form of negative regulation. Interestingly, a cluster of members belonging to the CiPSB subfamily on a 15 kb region on chromosome segment CI01000319, including CiPSB8, 9, 9b, and 10, showed marked responses to high density and saline-alkali stress. It appears that CiPS genes confer stress tolerance through the regulation of common genes, as well as specific genes. In summary, our genome-wide characterization, evolutionary, and transcriptomic analysis of CiPS genes in grass carp provides valuable information for characterizing the molecular functions of these genes and utilizing them to improve stress tolerance in aquaculture.