Metabolic mechanisms for anoxia tolerance and freezing survival in the intertidal gastropod, Littorina littorea

The gastropod mollusk, Littorina littorea L., is a common inhabitant of the intertidal zone along rocky coastlines of the north Atlantic. This species has well-developed anoxia tolerance and freeze tolerance and is extensively used as a model for exploring the biochemical adaptations that support these tolerances as well as for toxicological studies aimed at identifying effective biomarkers of aquatic pollution. This article highlights our current understanding of the molecular mechanisms involved in anaerobiosis and freezing survival of periwinkles, particularly with respect to anoxia-induced metabolic rate depression. Analysis of foot muscle and hepatopancreas metabolism includes anoxia-responsive changes in enzyme regulation, signal transduction, gene expression, post-transcriptional regulation of mRNA, control of translation, and cytoprotective strategies including chaperones and antioxidant defenses. New studies describe the regulation of glucose-6-phosphate dehydrogenase by reversible protein phosphorylation, the role of microRNAs in suppressing mRNA translation in the hypometabolic state, modulation of glutathione S-transferase isozyme patterns, and the regulation of the unfolded protein response.