Identification of the CYP gene family: insights into carotenoid metabolism associated with red shell in Meretrix meretrix

Abstract

Cytochrome P450 (CYP) belongs to a multigene superfamily in a wide array of organisms, integral to numerous physiological functions. Nevertheless, the association between CYPs and the shell pigmentation of marine mollusks has not been thoroughly investigated. In this study, there was a clear distinction in color parameters between red and white clams of Meretrix meretrix, and the carotenoid contents and antioxidant capacity of red clams were extremely significantly higher than that of white clams (P < 0.01). Furthermore, 42 candidate CYPs of M. meretrix (MmCYPs) were identified through transcriptome analysis, which was classified into four distinct clans (clan2, clan3, clan4, mito). The phylogenetic assessment highlighted highly conserved domains and motifs of MmCYPs, especially within their respective subfamilies. Additionally, transcriptomic data revealed varied expression patterns of MmCYPs in the mantles, and qRT-PCR validated that the expression profiles of candidate gene MmCYP2J2-like corresponded with those identified in the transcriptomic analysis, exhibiting elevated expression levels in red shell clams (P < 0.01). Importantly, the MmCYP2J2-like protein was predominantly localized in the epithelial cells of the mantle. The results of this study establish a link between detoxification genes and carotenoid metabolism, providing valuable insights for the functional characterization of MmCYPs involved in the development of red shell pigmentation, and establishing a molecular basis for breeding new clam varieties with enhanced carotenoid levels in the aquaculture.