Molecular characteristics of HSC70 gene and its expression in the golden apple snails, Pomacea canaliculata (Mollusca: Gastropoda)

Abstract

The heat shock cognate 70 (PHSC70) gene of the golden apple snail, Pomacea canaliculata, was cloned and characterized, which was 2275base pairs (bp) containing a single 1950bp open reading frame (ORF) that encoded a polypeptide of 650 amino acids. Genomic DNA of PHSC70 in P. canaliculata confirmed the presence of nine introns located at the coding region as well as the 5′-terminal untranslated region (UTR). BLAST analysis revealed that the PHSC70 gene shared high similarity with other known HSC70 genes. The phylogenetic analysis demonstrated a separate clustering of the PHSC70 with constitutive members from other mollusk species. Expression of PHSC70 in different tissues (gill, digestive gland, kidney and foot muscle) of the snails exposed to high (36°C) and low (9°C) temperatures was investigated. The results showed that PHSC70 transcript levels were constitutively modulated in non-stressed condition in above tissues. After the cold treatment, PHSC70 transcript levels decreased significantly in the gill, but had no obvious changes in the digestive gland, kidney and foot muscle. However, PHSC70 transcript levels increased significantly in all the tissues under the heat shock condition. In addition, PHSC70 protein was detected in different tissues from both young and adult snails by a Western blot. The result of quantitative immunofluorescence indicated that a large amount of PHSC70 proteins localize in the gill lamella cells. These results strongly suggested that PHSC70 may play an important role in mediating the physiological responses to the high temperature.