碳酸盐碱胁迫下尼罗罗非鱼氨代谢两种途径时序研究

为了解罗非鱼在碱水环境适应过程中的氨代谢机制,将尼罗罗非鱼(Oreochromis niloticus)放在(2、4、6 g/L)碳酸盐(Na HCO3)碱水环境中进行急性胁迫。检测碱胁迫72 h内的血氨浓度,肝、肾、鳃组织及水体、尿液、血液尿素浓度变化,肝、脑、鳃谷氨酰胺(Gln)浓度,肝、脑谷氨酰胺合成酶(GS)活性,肝氨甲酰磷酸合成酶(CPS)活性,不同组织中GS、CPS、谷氨酰胺酶(GLS)的基因表达变化。结果显示:急性胁迫下尼罗罗非鱼血氨浓度上升,于12 h到达峰值。随着血氨升高,各组织中的尿素浓度0~6 h快速升高,CPS活性0~2 h快速升高,基因相对表达量0~24 h升高,表明尿素代谢途径0-6 h内启动。肝谷氨酰胺浓度0~6 h快速升高到达峰值,肝GS活性0~6 h和12~24 h快速升高,组织中GS、GLS基因相对表达量在0~24 h升高,表明谷氨酰胺代谢途径0~6 h内启动。结果表明,在碱胁迫条件下,尼罗罗非鱼在胁迫早期同时启动尿素代谢途径与谷氨酰胺代谢途径共同参与调节血氨浓度。

Study on the timing sequence of two pathway of Oreochromis niloticus ammonia metabolism under the stress of carbonate alkalinity

This research was conducted to comprehend the mechanism of ammonia metabolism during the adaptation of tila-pia(Oreochromis niloticus)to alkaline environment(2, 4, 6 g/L NaHCO3).The concentration of serum ammonia, the concentrations of urea in liver, kidney, gill, water, urine and blood, the concentration of glutamine(Gln)in liver, brain and gill, the activities of glutamine synthetase(GS)in liver, brain and the activities of carbamyl phosphate synthetase (CPS)in liver, the changes in gene expression of synthetase, carbamyl phosphate synthetase, glutaminase(GLS)in dif-ferent tissues of O.niloticus were analyzed under acute stress in 72 h.The results showed that the blood ammonia concentra-tion of O.niloticus increased under acute stress, reaching its peak at 12 h.The concentration of urea in each tissue substan-tially increased from 0 to 6 h with the increase of blood ammonia.There was a dramatic growth of the activity of carbamyl phosphate synthase from 0 to 2 h.The expression quantity of carbamyl phosphate synthase went up from 0 to 24 h, which indicating that the urea metabolization pathway was activated within 0-6 h.The concentration of glutamine in the liver grew rapidly from 0 to 6 h and reached its highest point.The activity of glutamine synthase in the liver soared from 0 to 6 h and from 12 to 24 h.The expression of glutamine synthase and glutaminase in each tissue was on a rise at 0 to 24 h.It illustrated that glutamine metabolism was also activated within 0-6 h.The results indicated that O.niloticus activated urea metabolism pathway and glutamine metabolism pathway simultaneously to adjust blood ammonia concentration in the early stage of stress under alkali stress conditions.