褐牙鲆早期发育阶段CRH基因表达及 受甲状腺激素的影响

目的]探析褐牙鲆仔鱼早期发育阶段促肾上腺皮质激素释放激素基因(CRH)的表达情况及受甲状腺激素的影响作用,为开展牙鲆的人工繁育提供科学依据.方法]通过实时荧光定量PCR检测褐牙鲆早期发育阶段CRH基因表达量,以ELISA测定褐牙鲆仔鱼甲状腺激素(T3和T4)水平,并测定经外源T3浸泡处理后早期发育褐牙鲆仔鱼CRH基因表达量的变化情况,探究CRH和甲状腺激素在褐牙鲆早期发育阶段的影响及作用关系.结果]1~8日龄褐牙鲆仔鱼CRH基因相对表达量呈先升高后降低的变化趋势,在5日龄达最高值,显著高于其他日龄的仔鱼(P<0.05,下同).10~42日龄褐牙鲆仔鱼CRH基因主要在其头部表达,尾部CRH基因的相对表达量随着生长发育的进程而逐渐增加.褐牙鲆仔鱼变态前期甲状腺激素T4含量逐渐增加,变态高峰期迅速升高,在变态后期呈下降趋势.较其他早期发育时期,甲状腺激素T3在褐牙鲆变态期维持高水平,但含量低于甲状腺激素T4.22日龄褐牙鲆仔鱼经50 nmol/L外源T3处理2 h后,其头部和尾部CRH基因的相对表达量显著升高;但以外源T3处理8 h后,无论是头部还是尾部,CRH基因的相对表达量均呈显著下降趋势.结论]褐牙鲆早期变态发育需CRH基因高表达及甲状腺激素积累,二者对褐牙鲆早期变态发育阶段具有重要作用并呈互相代偿效应.

Effects of thyroid hormone on CRH gene expression in Paralichthys olivaceus at early development stage

Objective]The present study investigated expression of corticotropin releasing hormone (CRH) gene and in-fluence of thyroid hormone on it, in order to provide reference for artificial breeding of Paralichthys olivaceus. Method]CRH gene expression of P. olivaceus at early development was detected by real-time fluorescence quantitative PCR. Thyroid hormone(T3 and T4) level of P. olivaceus larvae and CRH gene expression after exogenous T3 immersion treatment were measured by ELISA method. The interaction between CRH and thyroid hormone at early development stage of P. olivaceus was studied. Result]During 1-8 dph, CRH gene expression went through up-down variation, and reached the peak at 5 dph, which was significantly higher than the value at other day ages(P<0.05, the same below). At 10-42 dph, CHR gene expression was mainly in head, and expression in tail increased with growth of P. olivaceus. T4 content gradually in-creased before metamorphosis, and soared at metamorphosis climax, then decreased at metamorphosis postclimax. Com-pared with other early development stages, T3 maintained at a high level during metamorphosis, but the content was lower than T4. After P. olivaceus at 22 dph treated with 50 nmol/L exogenous T3 for 2 hours, the expression of CRH in head and tail significantly increased;but aftet 8 hours, the expression in head and tail significantly decreased. Conclusion]At early metamorphosis stage, P. olivaceus needs to increase CRH expression and accumulate thyroid hormone. Both of them play important roles at early development stage of P. olivaceus and have compensatory effect between each other.