Transcriptomic Analysis of the Reproductive Effects on Immunity in the Clam Meretrix Petechialis During the Breeding Season

Abstract

Background: Immune defense and reproduction are both physiologically demanding processes, therefore the trade-off is expected between them in breeding season. Although this balance strategy has been extensively studied in many species, it is still rarely noticed in mollusc. Moreover, summer mortality of marine bivalve often occurs during breeding season and reproduction is suspected to play a significant role for the mass death. Results: To address if spawning affects immunity to cause clam death, we performed transcriptome and gene expression analyses in the clam Meretrix petechialis pre-/post-spawning. DEGs enrichment analysis revealed important immune signaling pathways and key genes changed after spawning. Further analysis showed females up-regulated genes involved in apoptosis, TLR signal pathway and heat shock, whereas males down-regulated complement-related genes after spawning. Additionally, both genders of clams up-regulated its immune response level to against Vibrio infection after spawning revealed by the changes of four immune-related DEGs. Conclusions: The spawning indeed affected the clam immune resistance. The immune and defense related genes and pathways obtained here provide important insights into the molecular mechanisms of physiological acclimation and immune response under reproduction-influence and offers some clues to explain the possible reason for clam summer mortality.