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Titolo:
Mitochondrial function and critical temperature in the Antarctic bivalve, Laternula elliptica
Autore:
Portner, HO; Hardewig, I; Peck, LS;
Indirizzi:
Alfred Wegener Inst Polar & Meeresforsch, D-27515 Bremerhaven, Germany Alfred Wegener Inst Polar & Meeresforsch Bremerhaven Germany D-27515 any British Antarctic Survey, Cambridge CB3 0ET, England British Antarctic Survey Cambridge England CB3 0ET idge CB3 0ET, England
Titolo Testata:
COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR AND INTEGRATIVE PHYSIOLOGY
fascicolo: 2, volume: 124, anno: 1999,
pagine: 179 - 189
SICI:
1095-6433(199910)124:2<179:MFACTI>2.0.ZU;2-7
Fonte:
ISI
Lingua:
ENG
Soggetto:
STANDARD METABOLIC-RATE; INNER MEMBRANE; PROTON PERMEABILITY; MUSCLE MITOCHONDRIA; LIVER-MITOCHONDRIA; ENERGY-METABOLISM; OXIDATIVE-PHOSPHORYLATION; COUPLED MITOCHONDRIA; ARENICOLA-MARINA; SUBSTRATE CYCLE;
Keywords:
activation energy; antarctic bivalve; cold adaptation; critical temperature; isocitrate dehydrogenase; Laternula elliptica; mitochondria; proton leak;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Life Sciences
Citazioni:
53
Recensione:
Indirizzi per estratti:
Indirizzo: Portner, HO Alfred Wegener Inst Polar & Meeresforsch, Postfach 12 01 61, D-27515 Bremerhaven, Germany Alfred Wegener Inst Polar & Meeresforsch Postfach 12 01 61 Bremerhaven Germany D-27515
Citazione:
H.O. Portner et al., "Mitochondrial function and critical temperature in the Antarctic bivalve, Laternula elliptica", COMP BIOC A, 124(2), 1999, pp. 179-189

Abstract

Thermal sensitivities of maximum respiration and proton leakage were compared in gill mitochondria of the Antarctic bivalve Laternula elliptica for an assessment of the contribution of mitochondrial mechanisms to limiting temperature tolerance. Proton leakage was measured as the oxygen consumption rate during blockage of oxidative phosphorylation (state IV respiration + oligomycin). The maximum capacity of NADP dependent mitochondrial isocitratedehydrogenase (IDH) was investigated as part of a proposed mitochondrial substrate cycle provoking proton leakage by the action of transhydrogenase. State III and IV + respiration rose exponentially with temperature. Thermalsensitivities of proton leakage and IDH were unusually high, in accordancewith the hypothesis that H+ leakage is an enzyme catalysed process with IDH being involved. In contrast to proton leakage, state III respiration exhibited an Arrhenius break temperature at 9 degrees C, visible as a drop in thermal sensitivity close to, but still above the critical temperature of the species (3-6 degrees C). Progressive uncoupling of mitochondria led to a drop in RCR values and P/O ratios at high temperature. The same discontinuity as for state III respiration was found for the activity of mitochondrialIDH suggesting that this enzyme may influence the thermal control of mitochondrial respiration. In general, the high thermal sensitivity of proton leakage may cause an excessive rise in mitochondrial oxygen demand and a decreased efficiency of oxidative phosphorylation. This may exceed the whole animal capacity of oxygen uptake and distribution by ventilation and circulation and set a thermal limit, characterized by the transition to anaerobic metabolism. (C) 1999 Elsevier Science Inc. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 07/07/20 alle ore 06:15:55