Response of sulfide:quinone oxidoreductase to sulfide exposure in the echiuran worm Urechis unicinctus.

摘要

Sulfide is a natural, widely distributed, poisonous substance, and sulfide:quinone oxidoreductase (SQR) is responsible for the initial oxidation of sulfide in mitochondria. In this study, we examined the response of SQR to sulfide exposure (25, 50, and 150[NON-BREAKING SPACE]muM) at mRNA, protein, and enzyme activity levels in the body wall and hindgut of the echiuran worm Urechis unicinctus, a benthic organism living in marine sediments. The results revealed SQR mRNA expression during sulfide exposure in the body wall and hindgut increased in a time- and concentration-dependent manner that increased significantly at 12[NON-BREAKING SPACE]h and continuously increased with time. At the protein level, SQR expression in the two tissues showed a time-dependent relationship that increased significantly at 12[NON-BREAKING SPACE]h in 50 muM sulfide and 6[NON-BREAKING SPACE]h in 150[NON-BREAKING SPACE]muM, and then continued to increase with time while no significant increase appeared after 25 muM sulfide exposure. SQR enzyme activity in both tissues increased significantly in a time-dependent manner after 50 muM sulfide exposure. We concluded that SQR expression could be induced by sulfide exposure and that the two tissues studied have dissimilar sulfide metabolic patterns. A U. unicinctus sulfide-induced detoxification mechanism was also discussed.