Influence of oxygen partial pressures on protein synthesis in feeding crabs

1 Department of Zoology, University of Aberdeen, Aberdeen AB24 2TZ, United Kingdom; and 2 Laboratoire d'Ecophysiologie et Ecotoxicologie des Systèmes Aquatiques, Unité Mixte de Recherche 5805-OASU, Université Bordeaux 1 and Centre National de la Recherche Scientifique, Arcachon 33120, France Many water-breathing animals have a strategy that consists of maintaining low blood P O 2 values in a large range of water oxygenation level (4-40 kPa). This study examines the postprandial changes in O 2 consumption, arterial blood P O 2 , and tissue protein synthesis in the shore crab Carcinus maenas in normoxic, O 2 -depleted, and O 2 -enriched waters to study the effects of this strategy on the O 2 consumption and peptide bond formation after feeding. In normoxic water (21 kPa), the arterial P O 2 was 1.1 kPa before feeding and 1.2 kPa 24 h later. In water with a P O 2 of 3 kPa (arterial P O 2 0.6 kPa), postprandial stimulation of protein synthesis and O 2 consumption were blocked. The blockade was partial at a water P O 2 of 4 kPa (arterial P O 2 0.8 kPa). An increase in environmental P O 2 (60 kPa, arterial P O 2 10 kPa) resulted in an increase in protein synthesis compared with normoxic rates. It is concluded that the arterial P O 2 spontaneously set in normoxic Carcinus limits the rates of protein synthesis. The rationale for such a strategy is discussed. crustaceans; oxygen consumption; blood oxygen; hypoxia