关键词：
团头鲂;急性低氧;鳃;氧化还原稳态;细胞凋亡
摘 要：
为探究急性低氧对团头鲂（Megalobrama amblycephala）鳃组织氧化还原稳态及细胞凋亡的影响,本研究通过测定超氧化物歧化酶（superoxide dismutases,SOD）、过氧化氢酶（catalases,CAT）活性及丙二醛（malondialdehyde,MDA）的含量,检测急性低氧胁迫下鳃组织的氧化应激水平,并采用Hoechst染色法观察了团头鲂鳃组织细胞的凋亡,同时还利用qRT-PCR技术检测了团头鲂鳃组织中凋亡相关基因Caspase 3、Caspase 8的表达量。结果显示,在溶解氧含量为（2.0±0.1） mg/L的低氧环境下,团头鲂鳃组织中SOD、CAT活性及MDA的含量均在6 h、12 h时显著增加（P＜0.05）;且SOD活性与MDA含量的变化趋势相同,均呈上升趋势。此外,随低氧胁迫时间的延长,在6、12及24 h时鳃组织细胞凋亡的平均荧光强度分别为0 h的2.19倍（P＜0.05）、2.32倍（P＜0.05）及2.59倍（P＜0.05）,鳃组织中Caspase 3与Caspase 8基因表达水平均显著高于0 h（P＜0.05）。研究表明,团头鲂在急性低氧的水环境中会提高自身的氧化应激水平,激活凋亡相关基因Caspase 3、Caspase 8的活性,最终促使团头鲂鳃组织发生细胞凋亡。本研究结果为急性低氧下团头鲂鳃组织的生理状态和细胞凋亡应答情况的研究提供参考。
作 者：
YU Xinxin;WU Jiwen;ZHENG Guodong;ZOU Shuming;Genetics and Breeding Center for Blunt Snout Bream,Ministry of Agriculture and Rural Affairs;Shanghai Ocean University;Key Laboratory of Freshwater Aquatic Genetic Resources,Ministry of Agriculture and Rural Affairs;Shanghai Ocean University;National Demonstration Center for Experimental Fisheries Science Education,Shanghai Ocean University;
关键词：
Megalobrama amblycephala;;acute hypoxia;;gill;;redox homeostasis;;apoptosis
摘 要：
Dissolved oxygen(DO) is the most important environmental factor for fish survival and indicates healthy fish culture.Low DO in the water environment restricts the growth and development of fish and causes stress reactions in some fish,which may lead to death in serious cases.Being an important organ for fish respiration,the gills are the most sensitive organs to changes in the water environment.The gills are also the main sites for maintaining osmotic pressure and metabolizing waste in the fish.Blunt snout bream(Megalobrama amblycephala) is one of the main cultured fish in China and has the advantages of low breeding cost and delicious taste.However,blunt snout breams are extremely susceptible to hypoxia compared to carp,crucian carp,and other fish.The blunt snout breams often face hypoxia during breeding,which severely restricts the sustainable development of its artificial culture.Therefore,conducting relevant research on its hypoxia response mechanism is necessary.To explore the effect of acute hypoxia on redox homeostasis and cell apoptosis in the gill tissue of blunt snout bream,the oxidative stress levels in the gill tissue under acute hypoxic stress were detected by measuring the activities of SOD,CAT,and MDA.Apoptosis in the gill tissue of the blunt snout bream was observed using Hoechst staining.In addition,the expression of apoptosis-related genes Caspase 3 and Caspase 8 in the gill tissue of blunt snout bream was detected using qRT-PCR.The results showed that the contents of SOD,CAT,and MDA in the gill tissue of its artificial culture increased significantly(P<0.05) at 6 and 12 h under the hypoxic environment with DO of(2.0±0.1) mg/L.In addition,the activity of SOD and MDA similarly increased with increasing treatment time,reaching the highest value at 24 h of hypoxic treatment.However,with an increase in hypoxic stress time,the activity of CAT in the gill tissue showed a trend of first increasing and then decreasing,reaching its highest value after 12 h of hypoxia treatment.Fewer apoptotic cells were emitting blue fluorescence in the gill tissue at 0 h of hypoxia,while apoptotic cells with blue fluorescence increased sharply at 6 h of hypoxia,and apoptotic cells emitting blue fluorescence further increased at 12 and 24 h of hypoxia.In addition,with the prolongation of hypoxic stress time,the average fluorescence intensity of apoptosis in the gill tissue was 2.19times(P<0.05),2.32 times(P<0.05),and 2.59 times(P<0.05) of that at 0 h at 6,12,and 24 h,respectively.The expression of Caspase 3 and Caspase 8 in the gill tissue was significantly(P<0.05) higher than that at 0 h.The results of this study suggest that the acute hypoxic water environment around blunt snout bream increases oxidative stress level and activates the apoptosis-related genes Caspase 3 and Caspase 8 in the blunt snout breams,which eventually leads to apoptosis in the gill tissue.In conclusion,these results provide biological information on the physiological status and apoptotic response of the gill tissue of blunt snout bream under acute hypoxia and provide important reference values for subsequent studies on the apoptotic mechanism of fish under hypoxia.
