Expressional Characterization Of The Biological Clock Related Genes In The Liver And Heart Of Siniperca Chuatsi

Biological clock is the material base of circadian rhythm. It plays a key role in the organism of metabolism, immune regulation, cell cycle and others important processes. Regulating mechanism of circadian rhythm, especially the regulation of life cycle processes by biological clock, is crucial factor of the body's normal physiological processes. However, it remains ambiguous about the process of accurate molecular regulation maintaining circadian clock and there are major differences between species. In fish, the research about molecular clock system mostly concentrates on model species. However there was little related references on the cultured fish species.In the present study, we cloned the Clock (Circadian locomoter output cycles kaput) gene cDNA sequences of Siniperca chuatsi (GenBank accession number for KT895225) by RACE-PCR. Expression of the clock related genes was obtained by real-time fluorescence quantitative PCR (qRT-PCT) under the 12h-light and 12h-dark (LD) cycle condition. The circadian rhythmicity and correlation of these genes were analyzed. The main result are summarized as follows:(1) The full length of Clock gene cDNA sequence was 3698 bp, including the 5' untranslated region (5'UTR,412 bp), open reading frame (ORF,2697 bp) and 3' untranslated region (3'UTR,589 bp). The deduced protein molecular weight and isoelectric point were 101.76 kDa and 7.14, respectively.(2) In the liver, among the 13 clock genes (Bmal1, Clock, Cry1, Cry3, Cry-dash, Npas2, Npas4, Nrldl, Nrld2, Per1, Per3, Rora, Tim), the Cry-dash, Npas4, Nrld1, Per1 and Tim displayed circadian rhythms. In addition, among the 14 liver functional genes (ApoAl, ApoB, ApoC1, Cpt1, Cyp, Dhcr7, EL, Fas, Hmgcr, Ldlrl, LPL, Lxra, Ppara, Ppar?),8 genes including Cyp, EL, Hmgcr, Ldlrl, LPL, Lxra, Ppara, Ppar? displayed circadian rhythmic expression. The transcript levels of Tim, Npas4, Nrldl, Perl had positive correlations with Cyp, EL, Hmgcr, Ldlr1, LPL, Lxra, Ppara and Ppar?.(3) In the heart,9 clock genes (Bmal1, Clock, Cry1, Npas2, Nrld1, Nrld2, Per3, Rora and Tim) and 6 heart functional genes (Dusp28, Raph1, Rhobtb2, Rhobtb3, Slco5A1 and Socs3) were expressed with rhythmic manner. The transcript levels of Bmall, Clock, Cryl, Npas2, Nrld2, Per3, Rora and Tim positively correlated or negative correlated with the expression of Dusp28, Raph1, Rhobtb2, Rhobtb3, Slco5A1 and Socs3.Overall of the obtained results from this study provided comprehensive data about Clock genes and their expression regulation, and may aid us for a better understanding about the molecular mechanism on circadian clock regulation in fish, at least in Siniperca chuatsi.