Expression of stress response HSP70 gene in Asian paddle crabs, Charybdis japonica, exposure to endocrine disrupting chemicals, bisphenol A (BPA) and 4-nonylphenol (NP)

Abstract

The Asian paddle crab, Charybdis japonica, is a potential bio-indicator reflecting marine sediment toxicity as well as a commercially important species living along coastal areas in Korea. This study investigated its stress response by looking at the heat shock protein (HSP70) gene of C. japonica when the organism is exposed to bisphenol A (BPA) and 4-nonylphenol (NP). We characterized partial sequence of HSP70 as the stressresponse gene of C. japonica. The nucleotide sequence of C. japonica HSP70 is over 90% homologous with the corresponding gene of other crabs. Phylogenetic tree analysis revealed a close relationship between C. japonica HSP70 and HSP70 in other species of lobster and shrimps. HSP70 mRNA transcripts were detected in all the examined tissues of C. japonica, with the highest level in gills, the organ that most frequently came into contact with the external BPA or NP-laden water. As no reference data were available for C. japonica crab exposure, the BPA and NP 24-h LC50 values have not been previously determined. The expression of the C. japonica HSP70 gene to various BPA or NP concentrations during short and longer times was assessed. Gene expression was significantly induced in concentration- and time-dependent manners after BPA or NP exposures. These results support the postulation that crab C. japonica HSP70 could be a potential stress response molecular marker to monitor marine ecosystems.