光周期对红鳍东方鲀脑组织中GH和SS基因表达水平和昼夜表达模式的影响

Effects of photoperiod on expression level and daily expression pattern of GH and SS genes in brain of tiger puffer Takifugu rubripes

为研究光周期对红鳍东方鲀Takifugu rubripes脑组织中生长激素(Growth hormone,GH)基因、生长激素抑制素(Somatostatin,SS)基因表达水平和昼夜表达模式的影响,采用初始体质量为(7.89±0.42)g的红鳍东方鲀幼鱼为研究对象,养殖在试验桶(直径80 cm、深50 cm)中,海水温度为19~23℃,盐度为31~32,共设置5种光周期8L∶16D、12L∶12D、16L∶8D、20L∶4D、24L∶0D,每个处理组设3个平行,每桶放60尾鱼,试验周期为30 d,试验结束后全天取样,测定脑组织中GH、SS基因表达水平。结果表明:8L∶16D光周期处理组红鳍东方鲀脑组织中GH基因相对表达量显著高于其他光周期处理组(P<0.05);8L∶16D光周期处理组SS基因相对表达量显著高于24L∶0D组(P<0.05),其他处理组SS基因相对表达量无显著性差异(P>0.05);GH和SS基因表达水平分别在12L∶12D和8L∶16D光照条件下呈现昼低夜高的特点。研究表明,结合GH和SS基因在不同光周期下的表达量及昼夜表达特点,长时间光照(16~24 h/d)并不利于红鳍东方鲀幼鱼生理节律的维持,本试验条件下最佳光照时长为8~12 h/d。

Juvenile tiger puffer Takifugu rubripes with initial body weight of(7.89±0.42)g was reared in a barrel with a depth of 50 cm and a diameter of 80 cm at a rate of 60 fish per barrel and exposed to photoperiod of 8L∶16D,12L∶12D,16L∶8D,20L∶4D,and 24L∶0D at water temperature of 19-23℃for 30 d with triplication.The growth hormone(GH)and somatostatin(SS)genes were analyzed in brains of tiger puffer to investigate effects of photoperiod on expression level and daily expression pattern of GH and SS genes in brain of tiger puffer.The expression of GH gene was shown to be significantly higher in brains of tiger puffer in 8L∶16D group than that in other groups(P<0.05),significantly higher expression level of SS gene in 8L∶16D group than at in 24L∶0D group(P<0.05),without significant difference in the expression levels of SS genes in the other groups.The expression levels of GH and SS gene were low at light phase and high at dark phase under 12L∶12D and 8L∶16D,respectively.The findings indicate that long-term light(16-24 h/d)is not conducive to the maintenance of the physiological rhythm of juvenile tiger puffer and that the optimal duration of illumination iss 8-12 h/d in the experiment.