Induction of centrum defects in amberjack Seriola dumerili by exposure of embryos to hypoxia

ABSTRACT:   Artificially hatched Seriola species have the problem of malformation, mainly in their vertebrae, head, and mouth parts. To clarify the cause of vertebral malformation, the effects of hypoxia during embryogenesis on the induction of centrum defects was investigated in artificially hatched amberjack Seriola dumerili . Firstly, 7-somite stage embryos were exposed to waters of 0, 12.5, 25, 50, and 100% dissolved oxygen (DO) for 0.5, 1, 2, 3, 4, and 5 h to confirm the effective dose (DO concentration and duration of exposure) of hypoxia that induces somitic disturbances in newly hatched larvae. Exposure of embryos to 12.5% DO concentration for longer than 0.5 h induced somitic disturbances. Following this result, centrum defects in juveniles were investigated by an induction experiment with embryos exposed to 12.5% DO for 2 h at the gastrula, 1- or 2-somite, 10-somite, 15-somite, or heart beating stage. This experiment revealed that centrum defects were induced only during somitogenesis, and somitic disturbances were the premonitory symptom of centrum defects. These results indicate hypoxia during somitogenesis as a possible cause of centrum defects in amberjack.     

Hypoxia‐induced changes in survival,immune response and antioxidant status of the Pacific white shrimp (Litopenaeus vannamei) fed with graded levels of dietary myo‐inositol

A 3‐hr experiment was conducted to investigate the effects of dietary myo‐inositol (MI) supplementation on survival, immune response and antioxidant abilities in Litopenaeus vannamei under acute hypoxia stress. Six practical diets were formulated with supplementation of graded levels (control group 0, 0.1, 0.2, 0.4, 0.8 and 1.6 g/kg dry diet) of MI and were randomly assigned to triplicate groups of L. vannamei (mean weight 0.40 ± 0.00 g) for 8 weeks. Ten healthy shrimp (final mean weight approximately 11–14 g) randomly selected from each tank were exposed to hypoxia stress after feeding trial. After 3‐hr acute hypoxia stress, survival of shrimp fed MI‐supplemented diets (except 0.1 and 0.4 g/kg diets) was significantly increased compared with the control group. Shrimp fed control diet had lower activities of alkaline phosphatase (AKP), acid phosphatase (ACP), total antioxidant capacity (T‐AOC) and glutathione peroxidase (GPX), and higher malondialdehyde (MDA) and protein carbonyl (PC) contents in hepatopancreas than those fed the MI‐supplemented diets. In addition, mRNA expression levels of heat shock protein 70 (Hsp70), catalase (CAT) and penaeidin were significantly differentially regulated in hepatopancreas. In summary, dietary MI supplementation may have a positive effect on improving resistance to acute hypoxia stress of L. vannamei.     

Temperature and dissolved oxygen influence growth and digestive enzyme activities of yellowtail kingfish Seriola lalandi (Valenciennes, 1833)

A 5 week experiment was carried out with juvenile yellowtail kingfish Seriola lalandi to investigate the interactive effects of water temperature (21, 24, or 27°C) and dissolved oxygen regime (normoxic vs. hypoxic) on the growth rate, feed intake and digestive enzyme activity of this species. Specific growth rate (SGR) was highest at 24°C, regardless of oxygen regime, but the SGRs of the fish exposed to hypoxia at 21, 24 and 27°C were 13%, 20% and 17% lower, respectively, than the SGRs recorded for the fish reared under normoxic conditions. The digestive enzyme activities (i.e. trypsin, lipase and α‐amylase) were influenced by temperature but did not appear to be affected by dissolved oxygen concentration. Information about the effects of water temperature and dissolved oxygen on feeding, growth and digestive capacity of juvenile yellowtail kingfish could contribute to improving feed management decisions for production of this fish species under different environmental conditions.     

低氧环境下卵形鲳鲹的氧化应激响应与生理代谢相关指标的研究

文章测定了急性和慢性低氧胁迫后卵形鲳鲹(Trachinotus ovatus)的氧化应激和生理代谢相关指标。结果显示,在(23±0.7)℃下,体质量(31.59±3.01)g的鱼在急性低氧胁迫条件下的个体成活率为100%,在慢性低氧胁迫条件下的成活率则不断下降,第11天时降为实验初始时的50%。急性低氧胁迫过程中随低氧胁迫时间延长鳃过氧化氢酶(CAT)活性下降,第3小时最低,随后升高,第24小时显著高于其他各组(P0.05)。还原型谷胱甘肽(GSH)、丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性随低氧持续先上升后恢复至正常水平,慢性低氧胁迫下鳃CAT活性与对照组相比显著降低(P0.05)。MDA、GSH含量和SOD活性则均显著升高(P0.05)。肝糖原(LG)在急性低氧胁迫过程中随低氧呈先下降后恢复的趋势,第12小时降至最低,第24小时恢复至对照组水平,慢性胁迫后LG下降。乳酸脱氢酶(LDH)水平在急性低氧胁迫过程中随低氧先升后降,第3小时达最大值,第24小时下降为对照组水平,慢低氧胁迫后LDH水平显著高于对照组(P0.05)。     

Predation on fish larvae by moon jellyfish <Emphasis Type="Italic">Aurelia aurita</Emphasis> under low dissolved oxygen concentrations

ABSTRACT:   Laboratory experiments were conducted to test the hypothesis that low dissolved oxygen concentrations have the potential to enhance the predation rate on fish larvae by moon jellyfish Aurelia aurita which is increasing in abundance in the coastal waters of Japan. Larvae of the red sea bream Pagrus major in four size classes (2.9, 4.1, 6.2 and 8.6 mm in standard length) were used as prey in a short-term predation experiment. No change in the bell contraction rate of the jellyfish (mean bell diameter, 100.4 ± 10.2 mm) was observed at the oxygen concentrations tested (1, 2 and 4 mg/L, and air-saturated, 5.5–6.0 mg/L), suggesting a strong tolerance to a decline in the oxygen concentration. More than 80% of the 2.5 and 4.1-mm size-class larvae were predated on by the jellyfish at all oxygen concentrations during the 15-min trials in 10-L tanks. The 6.2 and 8.6-mm size-class larvae were able to escape from the jellyfish apparently due to their developed swimming ability at the two higher dissolved oxygen concentrations. There was an increase in predation on larvae of these two size classes at the two lower dissolved oxygen concentrations. Predation by moon jellyfish on fish larvae can be more intense at low dissolved oxygen concentrations that commonly occur in the coastal waters of Japan.     

The effect of plant‐based diet and suboptimal environmental conditions on digestive function and diet‐induced enteropathy in rainbow trout (Oncorhynchus mykiss)

This experiment investigated intestinal enteropathy and digestive function of rainbow trout challenged with soybean meal‐based diet (SBM) at optimal or suboptimal environments created by normal or reduced water flow, respectively. Oxygen level remained above 7 mg L^‐1 for optimal environment and between 4 and 5 mg L^‐1 for suboptimal environment. Triplicate groups of fish (mean body weight 74 g) were fed fishmeal‐based diet (FM) or SBM at optimal environment in period 1 (28 days). In period 2 (42 days), fish were subjected to a change from FM to SBM or remained on the same diet as used in period 1. The fish were also exposed to change from optimal to suboptimal environment or remained under optimal conditions. The fish subjected to change from FM to SBM, regardless of their environment, showed similar degree of enteropathy from day 14. Lipid and starch digestibility was lower in SBM‐fed fish at suboptimal environment compared to fish fed the same diet at optimal environment. Crude protein digestibility, however, was highest in SBM‐fed fish at suboptimal environment throughout period 2. In conclusion, in SBM‐fed rainbow trout, exposure to suboptimal environment did not change the degree of enteropathy; however, lipid and starch digestibility were further reduced.     

外源24-表油菜素内酯对低氧胁迫下黄瓜幼苗抗氧化系统及蛋白含量的影响

采用营养液水培,研究了根际低氧胁迫下外源24-表油菜素内酯(24-epiBR)对2个抗低氧能力不同的黄瓜品种(“绿霸春四号”和“中农八号”)叶和根组织中抗氧化系统及根系中可溶性蛋白和热稳定蛋白含量的影响。结果表明,营养液添加1×10^-3 mg/L 24-epiBR能显著提高黄瓜植株叶和根组织抗氧化酶SOD、POD活性,对CAT活性无明显影响,降低了O^.-₂和MDA含量,同时,根系可溶性蛋白和热稳定蛋白含量显著提高;与抗低氧性较弱的品种“中农八号”相比,24-epiBR处理对抗低氧性强的品种“绿霸春四号”效果更明显,表明外源24-epiBR处理通过促进抗氧化酶活性和蛋白含量的提高,降低低氧胁迫下植株体内ROS含量,增强植株低氧逆境的适应能力。     

钙对根际低氧胁迫下黄瓜幼苗可溶性蛋白表达的影响

采用营养液水培,以低氧耐性较弱的黄瓜品种‘津春2号’为试材,研究了外源钙和钙调素(Ca.M)抑制剂三氟拉嗪(TFP)对根际低氧胁迫下黄瓜幼苗根系和叶片可溶性蛋白表达的影响。结果表明:低氧下植株的生物量显著下降,施加外源Ca2+后生物量显著增加,而施加TFP后则在低氧胁迫的基础上进一步降低了植株的生物量。植株的根系可溶性蛋白含量在低氧下降低而在添加了Ca2+后升高;叶片的可溶性蛋白含量在低氧下升高,添加Ca2+后可溶性蛋白在处理6 d和9 d时高于低氧和对照处理;施加TFP后根系和叶片的可溶性蛋白均下降。SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)分析表明,不同处理在根系中至少有9种蛋白表达量发生明显变化,其相对分子质量(×103)分别为17.2、19.7、24.0、31.5、35.0、51.2、64.8、75.0、83.0;叶片中也有7种蛋白表达量发生了变化,其相对分子质量(×103)分别为14.0、21.0、34.0、37.2、39.0、46.5、58.5。外源Ca2+显著增加了黄瓜的生物量,调节根系和叶片中可溶性蛋白含量及其表达,缓解了低氧胁迫对植株的伤害,增强了黄瓜的低氧耐性。     

IL-24对瘢痕疙瘩成纤维细胞增殖、细胞周期和缺氧诱导因子-1α表达的影响

目的观察IL-24对瘢痕疙瘩成纤维细胞（KF）的抑制效应及缺氧诱导因子-1α（HIF-1α）表达的影响。方法建立KF组、携带绿色荧光蛋白表达质粒的KF组（pEGFP-KF组）、携带转染IL-24基因表达质粒的KF组（IL-24-pEGFP-KF组）,用噻唑蓝法及流式细胞术检测KF增殖、细胞周期变化。建立KF、pEGFP-KF、IL-24-pEGFP-KF细胞株裸鼠移植瘤模型,免疫组织化学检测KF中HIF-1α表达。结果 IL-24-pEGFP-KF组较pEGFP-KF组、KF组到达平台期延迟,IL-24明显抑制了细胞增殖（P〈0.05）。IL-24-pEGFP-KF组的G0/G1期比例明显高于pEGFP-KF组、KF组,而S、G2/M期比例明显降低（P〈0.05）。IL-24-pEGFP-KF组的HIF-1α表达明显低于pEGFP-KF组和KF组。结论 IL-24可抑制KF增殖和HIF-1α表达,阻止细胞周期于G0/G1期。     

长期慢性低氧对牦牛和黄牛血液中HIF-2α、 EPO水平及红细胞相关指标的影响

为探讨牦牛和迁饲黄牛血液中红细胞(RBC)、血红蛋白(HB)、低氧诱导因子-2α(HIF-2α)、促红细胞生成素(EPO)等因子对高原适应和习服的不同特征及调控机理,按照海拔低于3 500m和高于3 500m两组采集青海地区的牦牛血样,同时采集高山迁饲黄牛(海拔2 500m)及低海拔黄牛(海拔1 300m)血液,采用全自动血液分析仪测定血液中红细胞、血红蛋白、红细胞比容(HCT)、平均红细胞血红蛋白量(MCH)等;采用双抗夹心酶标法测血液中EPO、HIF-2α含量。通过t检验及单因素方差分析法分析指标间的差异性,并分析各指标与HIF-2α、EPO的相关性。结果表明,海拔高于3 500m牦牛组的RBC、HB、HCT显著升高,而HIF-2α和EPO水平却未发生显著变化。与迁饲黄牛和低海拔黄牛相比,牦牛血液中的RBC明显降低,而MCH、HIF-2α和EPO显著升高。牦牛血液中EPO、RBC、HB、HCT、MCH水平与HIF-2α水平呈显著相关;迁饲黄牛血液中红细胞分布宽度(RDW-SD)与EPO水平呈显著相关;低海拔黄牛血液EPO、MCH水平与HIF-2α水平呈显著相关。推测:海拔升高引起的低氧是影响牦牛血液RBC、HB、HCT改变的主要因素;与黄牛相比,低RBC、低MCH、高HIF-2α、高EPO水平是牦牛适应低氧的主要特征,且牦牛血细胞各指标对血液中HIF-2α水平的改变更敏感。提示牦牛通过遗传进化成功适应高原环境。