The SREC-I and SREC-II associated with epidermal growth factor in scavenger receptor family are the potential regulative transmembrane receptors in Larimichthys crocea

•LycSREC1 and LycSREC2 were firstly identified in Larimichthys crocea SCARFs subfamily.•The gene structures, the gene location maps and genetic locus were analyzed.•EGF domain might relate to binding and cleaning pathogenic bacteria.•Their temporal mRNA expression were up-regulated after challenge of Vibrio alginolyticus.•The results might be conducive to comprehend innate immune system of bony fish.

In innate immunity, the regulation of the immunologic gene expression plays a vital role in defense against pathogenic threat. The class F scavenger receptors (SCARFs), a kind of crucial immunologic type I transmembrane receptors, mainly involve in the signal transmission and eliminating pathogens in host immune system. In this study, the SREC-I and SREC-II of SCARFs in Larimichthys crocea (designated as LycSREC1 and LycSREC2 respectively) were first identified, the potential genetic locus relationships with other species were depicted and the features of gene expression after Vibrio alginolyticus stimulation were tested. The results demonstrated that the complete ORF sequences of two candidates were 3024 bp and 2832 bp (KM884873 and KM884874) respectively including some important domains and motifs, such as EGF/EGF-like domains, TRAF2-binding consensus motif, generic motif and atipical motif. The gene location maps and genetic locus interpreted that the DNA sequences of LycSREC1 and LycSREC2 were 7603 bp and 4883 bp, and some locus had changed compared with human being, but three more crucial genetic locus were conservative among ten species. Furthermore, quantitative real-time PCR (qRT-PCR) analysis indicated that the highest mRNA expression of LycSREC1 and LycSREC2 were both in liver among eight detected tissues, and their expression were up-regulated by V. alginolyticus stimulation. All these findings would contribute to better understanding the biologic function of SCARFs in defending against pathogenic bacteria challenge and further exploring the innate immune of sciaenidae fish.