Myofibrilar functional desregulation in fish: a new biomarker of damage to pesticides.

CRUPKIN ANDREA CARINA; ITURBURU FERNANDO GASTÓN; CRUPKUN MARCO; MENONE MIRTA LUJÁN

Santos

Congreso; XII Congreso SETAC Latinoamerica; 2017

Society of Environmental Toxicology and Chemistry

The myofibrils proteins are very susceptible to oxidative stress, exhibiting polymerization, insolubilization, polypeptide chain breakdown, and amino acid destruction and consequently denaturation and aggregation of biopolymers.Endosulfan (ES) modificates the ultrastructure of the skeletal muscle fibers and causes changes the swimming behavior of fish. The objective of the present work was to explore the integrity and functionality of myofibrils (Mf) in the freshwater fish Australoheros facetus exposed to 0.5 and 10 g/L ES during 24 h. Myofibrils were analyzed for contractile function by monitoring with a phase contrast microscopy. Miofibrilar Mg2+ Ca2+ ATPase and Mg2+ (EGTA) ATPase activities, Ca2+ sensitivity, SDS-PAGE profiles of Mf and lipid peroxidation were also analyzed. As expected, after addition of contraction buffer Mf from control fish contracted. On the contrary, Mf from fish exposed at 0.5 g/L ES showed a partial contraction and not any of those from fish exposed at 10 g/L ES contracted. As judged by its high Mg2+ Ca2+ ATPase activity and low Mg2+ (EGTA) ATPase activity, control Mf showed good functionality. In Mf from fish exposed to 0.5 and 10 g/L ES the activities of these enzymes were similar, suggesting denaturation or degradation of some component of tropomyosin?troponin complex. SDS-PAGE patterns of Mf from fish exposed to ES showed degradation of myosin heavy chain and of tropomyosin. Similar values of TBARS were found in both control and exposed Mf, suggesting that lipid oxidation would not be related with the above mentioned changes. The effects observed expand the knowledge about the mode of action of ES in muscle and could be used as biomarkers of damage in fishes.