A diet rich in polyunsaturated fatty acids improves the capacity for HSP70 synthesis in adult scallop Argopecten purpuratus and their offspring

In scallops, aerobic power requirements of gonad maturation reduce HSP70 synthesis capacity in response to thermal or hypoxia stress. As dietary lipid quality is crucial for membrane function, we predicted that supplementing Argopecten purpuratus broodstock with essential polyunsaturated fatty acids (PUFA) during gonadal maturation would mitigate the loss in adult performance while favoring that of larvae. Scallops were fed during reproductive conditioning with microalgal diets with high and low PUFA contents, while a control group was maintained in natural conditions. After maturation, scallops of each treatment were kept at normal temperature (18 degrees C) or stressed by increasing the temperature (+6 degrees C). Mature scallops fed each diet were stimulated to spawn, and the ensuing larvae were exposed to handling and thermal stress. Relative transcription of hsp70 mRNA was assessed by RT-qPCR, and HSP70 proteins were quantified by ELISA. Feeding a high-PUFA diet during reproductive conditioning enhanced HSP70 induction (at transcription and protein levels) by mature A. purpuratus in response to thermal stress. By contrast, neither scallops matured in the natural environment nor those fed the low-PUFA diet increased HSP70 levels after thermal stress; hsp70 mRNA levels were also reduced. Offspring from broodstock fed a high-PUFA diet increased induction of HSP70 after exposure to handling and handling plus thermal stress relative to offspring of scallops fed a low-PUFA diet. Survival of these larvae was also enhanced. Feeding adult scallops with appropriate PUFA during reproductive conditioning could improve adult stress responses and favor stress responses and survival of ensuing larvae.