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Production of reactive oxygen species by isolated mitochondria of the Antarctic bivalve Laternula elliptica (King and Broderip) under heat stress.

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  • Biology
  • Chemistry
  • Ecology

Abstract

PII: S1532-0456(02)00212-0 Comparative Biochemistry and Physiology Part C 134 (2003) 79–90 1532-0456/03/$ - see front matter � 2002 Elsevier Science Inc. All rights reserved. PII: S1532-0456Ž02.00212-0 Production of reactive oxygen species by isolated mitochondria of the Antarctic bivalve Laternula elliptica (King and Broderip) under heat stress K. Heise , S. Puntarulo , H.O. Portner , D. Abele *a b a a,¨ Alfred Wegener Institute for Polar and Marine Research, Columbusstr., 27568 Bremerhaven, Germanya Physical Chemistry – PRALIB, School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentinab Received 16 May 2002; received in revised form 30 September 2002; accepted 1 October 2002 Abstract Formation of reactive oxygen species (ROS) in mitochondrial isolates from gill tissues of the Antarctic polar bivalve Laternula elliptica was measured fluorimetrically under in vitro conditions. When compared to the rates measured at habitat temperature (1 8C), significantly elevated ROS formation was found under temperature stress of 7 8C and higher. ROS formation correlated significantly with oxygen consumption in individual mitochondrial preparations over the entire range of experimental temperatures (1–12 8C). ROS generation per mg of mitochondrial protein was significantly higher in state 3 at maximal respiration and coupling to energy conservation, than in state 4q, where ATPase-activity is inhibited by oligomycin and only proton leakage is driving the residual oxygen consumption. The percent conversion of oxygen to the membrane permeant hydrogen peroxide amounted to 3.7% (state 3) and 6.5% (state 4q) at habitat temperature (1 8C), and to 7% (state 3) and 7.6% (state 4q) under experimental warming to 7 8C. This is high compared to 1–3% oxygen to ROS conversion in mammalian mitochondrial isolates and speaks for a comparatively low control of toxic oxygen formation in mitochondria of the polar bivalve. However, low metabolic rates at cold Antarctic temperature

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