Osmoregulation in decapod crustaceans: physiological and genomic perspectives

A central question in evolutionary biology represents understanding the molecular basis of adaptive response to differing environmental salinity gradients. The capacity to osmoregulate is considered to be the principal function through which adaptation occurs in different or fluctuating osmotic niches. Decapod crustaceans represent an interesting research group for exploring the underlying genetic/genomic mechanisms involved with this process. The genomic basis of osmoregulation involves modifying expression patterns of candidate genes for ionic balance for short-/long-term acclimation to salinity change while long-term persistence in the altered salinity conditions can facilitate adaptation via novel mutations over an evolutionary time frame. So far, 32 candidate genes have been identified that have important functional roles in maintaining ionic balance across decapod crustacean lineages. Certain genes are considered to play principal/vital roles while others apparently have secondary or minor roles. This group of genes falls under several broad biological categories including: sensing osmotic stress, signal transduction, activating candidate genes, osmotic stress tolerance, ion transportation, active ion exchange, and regulation of cell volume. Most studies conducted to date have focused only on a few principal genes to better understand osmoregulatory processes, while minor role-playing genes remained largely unexplored. The information available currently reviewed here can provide important clues to decipher the molecular mechanisms involved with osmoregulation broadly across crustacean lineages.