Genome-wide identification of the SR gene family in Procambarus clarkii and their expression responses to Vibrio parahaemolyticus under non-lethal heat shock

Scavenger receptors (SRs) are key pattern-recognition receptors in immunity, with SRCR domain-containing members (SRCRs) playing vital roles. This study systematically analyzed SRCR genes in Procambarus clarkii via genome-wide screening and identified six family members. These genes exhibit diverse molecular characteristics, with their encoded proteins varying in length (535–2970 aa), molecular weight (60.13–333.02 kDa), and stability (mostly unstable). Structural analysis revealed diverse gene structures, conserved SRCR domains, and an even distribution across six chromosomes, with Loxl2 showing evolutionary conservation with Eriocheir sinensis. Tissue-specific expression analysis by qPCR indicated high expression in hemocytes (immune relevance), gills (Loxl2, pathogen response), hepatopancreas (metabolism/detoxification), and intestine (LOC123759426, intestinal immunity). After non-lethal heat shock (NLHS) and bacterial challenge, LOC123770744 and LOC123759426 showed significant expression changes, indicating roles in stress responses, while the other genes exhibited varying degrees of differential expression. This study clarifies the characteristics and potential immune roles of SRCRs in P. clarkii.