碱度驯化对大鳞鲃幼鱼血液生理生化及肝脏抗氧化系统的影响

Effects of alkalinity acclimation on blood physiology and biochemistry and liver antioxidant system of juvenile Luciobarbus capito

中文关键词: 大鳞鲃  碱度  生理生化  抗氧化酶

英文关键词: Luciobarbus capito  Alkalinity  Physiological and biochemical  Antioxidant enzymes

中文摘要:

      为了从血液生理生化、肝脏抗氧化应激等方面研究大鳞鲃(Luciobarbus capito)对碱度驯化的生理适应性变化，选择体重为(13.66±1.26) g的大鳞鲃幼鱼开展NaHCO3碱度适应性驯化实验，空白组一直处于淡水中养殖，驯化组经20 mmol/L的碱度适应性驯养7 d后再放入40 mmol/L的碱度水体中，未驯化组直接放入40 mmol/L的碱度水体中，测定并比较了鱼体放入40 mmol/L碱度水体中第0 h、6 h、12 h、24 h、48 h、96 h、7 d幼鱼血液生理生化指标和肝组织抗氧化系统相关指标变化。结果显示，驯化组和未驯化组鱼体的血液渗透压、白细胞、淋巴细胞、中性粒细胞、单核细胞、血红蛋白、红细胞、血小板、尿素、白蛋白含量和血小板压积等生理生化指标以及肝组织抗氧化系统中的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)和丙二醛(MDA)在0 h~7 d的碱度胁迫过程中，均表现为先升高后降低的变化趋势(P<0.05)，且驯化组峰值大小均显著性低于未驯化组(P<0.05)，空白组在此期间均未表现出显著性变化(P>0.05)。驯化组鱼的血常规指标参数和肝脏组织的SOD、CAT出现峰值的时间均晚于未驯化组。驯化组鱼体在高碱度胁迫第7天时，其血液中的尿素浓度、淋巴细胞、单核细胞、血红蛋白、红细胞、血小板、白蛋白含量、谷草转氨酶(AST)、谷丙转氨酶(ALT)以及肝组织中的SOD、CAT、GSH-Px、MDA参数均显著性低于未驯化组(P<0.05)。研究表明，大鳞鲃幼鱼经过一定程度的碱度驯化后，在遭受更高碱度的水环境胁迫时，从生理层面反映出机体具有更强的适应性。

英文摘要:

      There are approximately 64 million hm2 of low-lying saline-alkali water resources in inland China, accounting for 55% of the total lake area. The characteristics of saline-alkali water are: high salt content, high alkalinity (high pH), and complex ion composition. Most freshwater fish cannot survive or reproduce in these conditions. To utilize saline-alkali water resources for aquaculture, researchers have introduced salt-tolerant fish, such as Luciobarbus capito, Chalcalburnus chalcoides aralensis, Leuciscus waleckii, and Oreochromis niloticus. In the initial stage of aquaculture, fish fry are not yet adapted to saline-alkali conditions because their body structure and physiological functions are not underdeveloped. The survival rate of juvenile fish is low because of the stress response to saline-alkali water. Studies of saline-alkali aquaculture have shown that proper acclimation can effectively improve the survival rate, growth, antioxidant, and immune properties of fish. L. capito belongs to the Cyprinidae family (subfamily Barbinae). It occurs mainly in the Caspian Sea and the Aral Sea of Western Asia. L. capito is an economically important fish, with adults weighing 5~ 10 kg. The species has excellent breeding characteristics, high saline-alkali tolerance, varied food habits, fast growth, delicious meat, and strong stress resistance. In 2003, it was introduced from Uzbekistan to China. To date, research has reported on L. capito artificial breeding technology and breeding biology but has not yet considered salt-alkali domestication. To study the physiological adaptability of L. capito to alkalinity with regards to blood physiology, biochemistry, and antioxidative stress, we used juvenile L. capito (13.66±1.26) g to test NaHCO3 alkalinity acclimation. The control group was cultivated in freshwater. The acclimation group was subjected to 20 mmol/L alkalinity for 7 d and then placed in 40 mmol/L alkaline water. The non-acclimation group was placed in 40 mmol/L alkaline water. The experimental media were prepared with tap water and NaHCO3 (domestic, analytically pure) after aeration for 2 d, and the alkalinity was measured and calibrated by acid-base titration. The fish were fed once a day and fasted for 24 h before sampling. Blood physiological and biochemical indices (water osmotic pressure, white blood cells, lymphocytes, neutrophils, monocytes, hemoglobin, red blood cells, platelets, platelet hematocrit, urea, and albumin), as well as indices related to the liver antioxidant system of juvenile fish in 40 mmol/L alkalinity water, were measured at 0 h, 6 h, 12 h, 24 h, 48 h, 96 h, and 7 d. In the control group, the same sampling was conducted at the corresponding moments. The physiological and biochemical indices for both domesticated and non-domesticated fish initially increased and then decreased across the sampling period (P<0.05). In both the domesticated and non-domesticated groups, the antioxidant indices of fish liver tissue, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA), increased initially and then decreased across the sampling period (P<0.05). The peak values of each parameter in the domesticated group were significantly lower than those of the non-domesticated group (P<0.05). No significant changes were observed in the control group during this period (P>0.05). The peak values of leukocytes, lymphocytes, neutrophils, and monocytes appeared at 48 h in the acclimated group and at 24 h in the non-acclimated group; the blood hemoglobin content, red blood cell content, platelet content, hematocrit, SOD, and CAT peaked in both the acclimated and non-acclimated groups at 24 h. After 7 d, the urea, lymphocyte, monocyte, platelet, red blood cell, hemoglobin, and albumin content of the blood and aspartate aminotransferase (AST), alanine aminotransferase (ALT), SOD, CAT, GSH-PX, and MDA content of the liver tissue were significantly lower in the acclimation group than in the non-acclimation group (P<0.05), but the plasma albumin content and glutathione catalase in the acclimated group returned to the level of the control group (P>0.05). Studies have shown that after alkalinity acclimation, juvenile L. capito are less stressed and the body tissue shows less damage and greater recovery under high alkalinity. At the physiological level, the body has higher adaptability. This study provides a theoretical basis for the establishment of saline-alkali aquaculture technology for the cultivation of L. capito that is based on the adaptability of the species to gradual changes in the alkalinity of the environment.