The cooperative expression of Heat Shock Protein 70 KD and 90 KD gene in juvenile Larimichthys crocea under Vibrio alginolyticus stress.

Heat shock proteins (HSPs) play significant roles in the immune response of fish in defending against diverse environmental threats or stresses. In this study, two complete HSP70 and HSP90 genes of Larimichthys crocea (designated as LycHSP70 and LycHSP90) were identified and characterized (GenBank accession no. KT456551 and KT456552). The complete open reading frame (ORF) fragments of LycHSP70 and LycHSP90 were 1917 bp and 2151 bp, encoding 638 and 716 amino acids residues respectively. Many significant functional domains and motifs were found, such as Hsp70 family signatures, Hsp90 family signatures, ATP-GTP binding site and EEVD motif regions, and they were associated with relative functions. Phylogenetic relationship and BLASTp analysis interpreted that they were unambiguously assigned to HSP70 and HSP90 family. The total length DNA of LycHSP70 was 7889bp, LycHSP90 was 5618 bp, and the gene location mapping were analyzed based on the whole-genomic DNA sequence of L. crocea. LycHSP70 and LycHSP90 were constantly expressed in eight tested tissues, with their expression peaks appearing in liver. Spleen, brain and head kidney also witnessed higher expression level. LycHSP70 and LycHSP90 were significantly induced by pathogenic bacteria V. alginolyticus, and they were both up-regulated in liver and spleen from 0 to 72 h post-injection. All the findings would contribute to better understanding the biologic function of HSPs in defending against pathogenic bacteria challenge and further exploring the innate immune response in fish.