Metabolic Support of Anaerobiosis in Embryos of the Annual Killifish Austrofundulus limnaeus

Abstract

Embryos of the annual killifish Austrofundulus limnaeus display a remarkable tolerance to anoxia during development, most notably during embryonic diapause. Little is known about the metabolic or enzymatic changes that accompany this state of anoxia tolerance. This study examined the metabolic changes associated with exposure to anoxia by measuring the activity of the enzyme phosphoenolpyruvate carboxykinase (PEPCK), and by profiling the concentration of 31 metabolites ranging from amino acids to citric cycle intermediates at 4 different developmental stages, diapause 2 (DII), 4 days post diapause (dpd), 12 and 22 dpd. Embryos of A. limnaeus showed stage specific changes in concentrations of several metabolites. The most notable changes in metabolite concentration in response to anoxia were the increases of lactate, alanine, GABA and succinate as well as a pronounced decrease in aspartate concentrations. However, a complete understanding of the mechanisms by which anoxia tolerance is achieved remains elusive. Further studies into the tissue specific responses of anoxia would enable greater resolution when attempting to explain changes in concentrations of metabolites both during development and in response to anoxic insult.