Anaerobic metabolic strategy of the glacial relict isopod Saduria (Mesidotea) entomon

Abstract

The glacial relict isopod Saduria (fidesidotea) entomon (L.) was kept under anoxia for u p to 300 h (S, 7 ?h; T, 8 "C). Glycogen was found in normoxic concentration of 20 to 30 wmol g-' dry wt; it decreased rapidly in anoxia for the first 100 h, after whlch the decrease slowed. The glycolytlc flux decreased after 100 h by a factor of 10. Blood glucose increased dunng the period of hlgh glycolytic flux, but, corresponding to the decrease in glycolytic flux after 100 h , it decreased agaln, remaining however above normoxic values. S, entomon forced to be active under anoxla accumulated lactate, but when quiescent showed practically no increase in lactate. Quiescent S. entomon showed a steady accumulation of alanine, which inhibits the activity of pyruvate klnase and is thus responsible for the reduction in glycolytic flux. This anaerobic strategy, which makes it possible to survive extended periods of anoxia, is unique among crustaceans.