Transcriptome and metabolome analyses provide insights into the salinity adaptation of clam Ruditapes philippinarum

Abstract

Salinity is an important environmental factor affecting the growth and survival of marine organisms. Marine shellfish possess the efficient osmoregulatory mechanism to cope with either hypo- or hyperosmotic stress. However, little is known about the molecular and metabolic adaptation involved in the osmotic regulation of these intertidal habitants. The Manila clam Ruditapes philippinarum is a worldwide cultured intertidal shellfish, which usually encounters a great risk of salinity stress in its coastal habitats. In the present study, the integrated analysis of transcriptomics and metabolomics was performed to investigate the transcriptional and metabolic profiles of the clams in response to abrupt salinity decrease. The comparative transcriptome analysis uncovers the changes of genes involved in ion channel activation, amino acid metabolism, and energy metabolism in the salinity-stressed condition. The metabolomics analysis reveals that the glucose-succinate pathway may play a critical role in energy metabolism during the osmotic stress. The multi-omics analysis reveals that neural adaptation to salinity stress may be potentially regulated by arachidonic acid metabolism and glutathione metabolism. The important metabolites (12-HPETE, PGEs, and spermine) may be served as the signaling molecules in response to acute salinity stress in the intertidal shellfish. These findings suggest that clams may get through the osmotic stress by ion channel activation, neural adaptation, and anaerobic metabolism to maintain their energy homeostasis for maximum survival. The present study provides great insights into the molecular and metabolic strategies of intertidal shellfish in response to salinity stress, and uncovers the new potential signaling metabolites to assess the health states of molluscs in aquaculture.