高碱环境下青海湖裸鲤氮废物排泄及相关基因的表达规律  

Nitrogenous waste excretion and gene expression of nitrogen transporter in Gymnocypris przewalskii in high alkaline environment

作　　者：衣晓飞[1,2] 来琦芳[1] 史建全[3] 高鹏程 周凯[1] 祁洪芳[3] 王慧[1] 么宗利[1] 

机构地区：[1]中国水产科学研究院东海水产研究所盐碱水域渔业工程技术研究中心(上海),上海200090 [2]上海海洋大学水产与生命学院,上海201306 [3]青海湖裸鲤救护中心,青海西宁810016

出　　处：《中国水产科学》2017年第4期681-689,共9页Journal of Fishery Sciences of China

基　　金：上海市科学技术委员会科研计划项目(14ZR1449800);中央级公益性科研院所基本科研业务费专项(中国水产科学研究院东海水产研究所)(2012M05)

摘　　要：采用个体生理学及定量PCR方法,研究了青海湖裸鲤(Gymnocypris przewalskii)在32 mmol/L(CA32)和64 mmol/L(CA64)碳酸盐碱度胁迫下氮废物排泄规律及鳃和肾组织中Rhesus type b glycoproteins(Rhbg)、Rhesus type c2 glycoproteins(Rhcg2)与urea transporter(Ut)基因的表达规律。结果显示,在32 mmol/L碱度胁迫整个过程中及64 mmol/L碱度胁迫初期裸鲤氨氮排泄率显著降低,但在64 mmol/L碱度胁迫8~20 h、24~72 h时氨氮排泄率基本恢复到胁迫前水平,在32 mmol/L碱度胁迫12~16 h、20~24 h及64 mmol/L碱度胁迫16~48 h时尿素氮排泄率显著升高。定量PCR结果显示,Rhbg、Rhcg2、Ut基因在胁迫过程中都有表达上调趋势,其中32 mmol/L碱性环境下鳃组织中Rhbg基因在胁迫12 h时表达明显上调;64 mmol/L碱性环境下鳃组织中Rhcg2基因在胁迫6 h、48 h、72 h表达明显上调,Ut基因在胁迫6 h表达明显上调,肾组织中Rhcg2基因在胁迫6 h表达明显上调。以上结果表明,裸鲤在高碱环境下虽然前期氮废物排泄受到抑制,但后期会通过启动Rh基因高表达恢复氨氮排泄,同时启动Ut高表达来增加尿素氮排泄来进行氮废物排泄。这一特殊氮废物排泄策略有助于裸鲤更好地适应高碱性环境。Saline-alkaline water bodies are widely distributed in China. High alkalinity is one of the main stressors for the survival of aquatic animals in saline-alkaline water. Previous studies have established that ammonia excre- tion is inhibited when fish are acutely exposed to alkaline water. Przewalskii＇s naked carp, also known as Gymno- cypris przewalskii or the scale-less carp, is endemic to the austere environment of Lake Qinghai. Lake Qinghai has a high salinity （13 ppt） and a strong alkalinity （carbonate alkalinity approximately 29 mmol/L, pH 9.1-9.5）. Due to high evaporative water loss and extensive water diversion for agricultural use, the water level of the lake is de- creasing by 10 cm per year and the salinity and alkalinity levels are increasing by 7% and 0.5% per year, respec- tively. Some studies showed that G. przewalskii had evolved a variety of mechanisms, such as osmoregulation and ion regulation with low energy consumption, regulation of HCO3 secretion in intestines, and compensatory car- bonic anhydrase expression mechanism under metabolic alkalosis, to adapt to saline-alkaline environments. However, the mechanism of nitrogenous waste excretion is less well studied. In order to evaluate the effect of carbonate alkalinity stress on nitrogenous waste excretion in G. przewalskii, we exposed juvenile G przewalskii to 32 mmol/L and 64 mmol/L carbonate alkalinity water and measured ammonia and urea excretion rate after -6 h （pre-transfer）, 4 h, 8 h, 12 h, 16 h, 20 h, 24 h, 48 h, 72 h, 96 h, and 120 h （recovery） after initial exposure. We also measured Rhesus type b glycoproteins （Rhbg）, Rhesus type c2 glycoproteins （Rhcg2）, and urea transporter （Ut） expression in gill and kidney of G. przewalskii by real-time PCR. The results showed that G. przewalskii in alka- line water reduced ammonia excretion but increased urea excretion. Ammonia excretion rate decreased signifi- cantly over the entire exposure period in 32 mmol/L carbonate alkalinity water and the initial exposure per

关 键 词：青海湖裸鲤 碳酸盐碱度 氮废物排泄 Rh基因 Ut基因 

分 类 号：S963[农业科学—水产养殖]