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Titolo:
Mitochondrial oxyconformity and cold adaptation in the polychaete Nereis pelagica and the bivalve Arctica islandica from the Baltic and White Seas
Autore:
Tschischka, K; Abele, D; Portner, HO;
Indirizzi:
Alfred Wegener Inst Polar & Marine Res, D-27568 Bremerhaven, Germany Alfred Wegener Inst Polar & Marine Res Bremerhaven Germany D-27568 rmany
Titolo Testata:
JOURNAL OF EXPERIMENTAL BIOLOGY
fascicolo: 21, volume: 203, anno: 2000,
pagine: 3355 - 3368
SICI:
0022-0949(200011)203:21<3355:MOACAI>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
STANDARD METABOLIC-RATE; NIPPOSTRONGYLUS-BRASILIENSIS; HYDROGEN-PEROXIDE; TERMINAL OXIDASES; AZOTOBACTER-VINELANDII; LIVER-MITOCHONDRIA; PLANT-MITOCHONDRIA; OXYGEN-CONSUMPTION; ARENICOLA-MARINA; ASCARIDIA-GALLI;
Keywords:
Nereis pelagica; Arctica islandica; oxyconformer; oxyregulation; oxidative phosphorylation; electron transport pathway; oxygen consumption; isolated mitochondria;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Life Sciences
Citazioni:
58
Recensione:
Indirizzi per estratti:
Indirizzo: Portner, HO Alfred Wegener Inst Polar & Marine Res, D-27568 Bremerhaven, Germany Alfred Wegener Inst Polar & Marine Res Bremerhaven Germany D-27568
Citazione:
K. Tschischka et al., "Mitochondrial oxyconformity and cold adaptation in the polychaete Nereis pelagica and the bivalve Arctica islandica from the Baltic and White Seas", J EXP BIOL, 203(21), 2000, pp. 3355-3368

Abstract

The rates of oxygen uptake of the marine polychaete Nereis pelagica and the bivalve Arctica islandica depend on the availability of ambient oxygen. This is manifest both at the tissue level and in isolated mitochondria studied between oxygen tensions (Po-2) of 6.3 and 47.6 kPa (47-357 mmHg), Oxyconformity was found in both Baltic Sea (Kiel Eight) and cold-adapted White Sea populations of the two species. However, mitochondria isolated from WhiteSea specimens of N, pelagica and A. islandica showed a two- to threefold higher aerobic capacity than mitochondria prepared from Baltic Sea specimens. We tested whether mitochondrial oxyconformity can be explained by an additional electron pathway that is directly controlled by Po,. Mitochondrial respiration of both invertebrate species was inhibited by cyanide (KCN) and by salicylhydroxamic acid (SHAM), The overall rate of mitochondrial oxygen consumption increased at high Po,. Phosphorylation efficiency (ADP/O ratio)decreased at elevated Po-2 (27.5-47.6 kPa, 206-357 mmHg), regardless of whether malate or succinate was used as a substrate. In contrast to the invertebrate mitochondria studied, mitochondria isolated from bovine heart, as an oxyregulating control species, did not show an elevated rate of oxygen uptake at high Po, in any respiratory state, with the exception of state 2 malate respiration. In addition, rates of ATP formation, respiratory control ratios (RCR) and ADP/O ratios remained virtually unchanged or even tended to decreased. In conclusion, the comparison between mitochondria from oxyregulating and oxyconforming organisms supports the existence of an alternative oxidase in addition to the classical cytochrome c oxidase. In accordance with models discussed previously, oxidative phosphorylation does not explain the rate of mitochondrial oxygen consumption during progressive activation of the alternative electron transport system. We discuss the alternative system, thought to be adaptive in confined, usually hypoxic environments, where excess oxygen can be eliminated and oxygen levels can be kept low by an increase in the rate of oxygen consumption, thereby minimizing the risk of oxidative stress.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 13/07/20 alle ore 11:15:02