Abstract

The cyanide metabolising enzymes (rhodanese and mercaptopyruvate sulphurtransferase) were estimated in different tissues of three species of tilapia (Tilapia zilli, Sarotherodon galileus,and Oreochromis niloticus) from two locations (Aiba and Osinmo reservoirs, both in the South-Western region of Nigeria). The enzyme activities were carried out by measuring the amount of thiocyanate produced by the two enzymes using specific substrates in each case. There was no significant difference in the activity of rhodanese in the tissues of the tilapia species from Aiba River. Mercaptopyruvate sulphurtransferase (3-MST) presented a different pattern of distribution with significant difference in the gut of the tilapia species. The study showed the activities of two cyanide detoxifying enzymes (rhodanese and mercaptopyruvate sulphurtransferase) in the different tilapia species indicating the presence of strong cyanide detoxifying mechanisms.

Key words: Rhodanese, mercaptopyruvate sulphurtransferase, cyanide, tilapia, detoxification.