The Timeless (Tim) Gene Participates in Circadian Rhythm Regulation of the Ridgetail White Prawn, Exopalaemon carinicauda

Abstract

Simple Summary In this study, we cloned the full-length sequence of the timeless gene (Ec-tim) from ridgetail white prawn, Exopalaemon carinicauda. Bioinformatic analysis predicts that the encoded protein contains a conserved TIM domain, verifying the typical structural characteristics of clock proteins. Quantitative real-time PCR (qPCR) detection showed that Ec-tim was specifically highly expressed in the eyestalks with developmental stage-dependent expression patterns. Moreover, its expression exhibited circadian oscillation under different light–dark cycles and constant darkness, suggesting that Ec-tim is a key endogenous circadian clock gene. RNA interference (RNAi) experiments indicated that silencing Ec-tim significantly downregulated the expression of core clock genes period (per) and cryptochrome 1 (cry1), but markedly upregulated the ecdysone receptor gene (EcR). This regulatory relationship suggests that Ec-tim may participate in the modulation of ovarian development via the molting hormone pathway, and the detailed molecular mechanism remains to be further explored.