温度和盐度对吉富罗非鱼幼鱼肠道两种抗氧化酶活力的联合效应

采用中心组合设计和响应曲面法研究温度(12~34℃)和盐度(0~26)对吉富品系尼罗罗非鱼(Oreochromis niloticus)幼鱼(体长4.20±0.10 cm,体质量2.42±0.15 g)肠道超氧化物歧化酶(Superoxide Dismutase,SOD)、过氧化氢酶(Catalane,CAT)的联合效应。结果表明:1)温度对吉富罗非鱼幼鱼肠道SOD和CAT活力的线性效应和累积效应均极显著(P<0.01);盐度对吉富罗非鱼幼鱼肠道SOD活力线性效应显著(P<0.05),累积效应极显著(P<0.01);盐度对吉富罗非鱼幼鱼肠道CAT活力线性效应不显著(P>0.05),累积效应极显著(P<0.01);温度和盐度对SOD活力的互作效应极显著(P<0.01),对CAT活力的互作效应不显著(P>0.05)。2)响应曲面法分析表明,随着温度和盐度的增大,两种抗氧化酶的活力均呈先减小后增大的趋势。3)建立两种抗氧化酶活力与温度、盐度间关系的模型方程(SOD:决定系数R2=0.992 9,预测决定系数R2Pred.=0.939 2,P<0.01;CAT:决定系数R2=0.948 5,预测决定系数R2Pred.=0.647 1,P<0.01),两模型方程可用于预测吉富罗非鱼幼鱼肠道SOD和CAT的活力。4)优化结果显示,温度为24.15℃,盐度为11.75时,SOD活力最小值为9.80 U/mg,CAT活力最小值为9.28 U/mg,满意度函数值高达0.961。     

低氧胁迫对军曹鱼幼鱼抗氧化、免疫能力及能量代谢的影响

【目的】研究低氧胁迫对军曹鱼(Rachycentron canadum)幼鱼抗氧化、免疫能力和能量代谢的影响。【方法】幼鱼于(2.98±0.40) mg/L的低溶氧条件下养殖1周,分别测定其肝脏和肌肉组织的抗氧化、免疫相关酶活力以及能量供应物质。【结果】低氧胁迫过程中,幼鱼肝脏组织超氧化物歧化酶(SOD)活力显著升高(P 0.05)后逐渐下降(P 0.05),肌肉组织SOD活力呈波动上升趋势(P 0.05),肝脏和肌肉组织谷胱甘肽过氧化物酶(GPX)活力和丙二醛(MDA)含量均显著升高(P0.05)后,呈逐渐下降趋势,肝脏组织过氧化氢酶(CAT)先降(P0.05)后升至正常水平,肌肉组织CAT活力先升(P 0.05)后呈下降趋势;肝脏组织碱性磷酸酶(AKP)活力先降后升高(P 0.05),随后恢复至与对照组水平(P 0.05),肝脏酸性磷酸酶(ACP)活力先显著上升(P 0.05),随后恢复至正常水平(P 0.05);肌肉组织和肝脏组织乳酸脱氢酶(LDH)活力变化趋势一致,均为先显著升高(P0.05),之后呈降低趋势;肝糖原在低氧胁迫后呈先下降(P 0.05),后恢复至对照组水平(P 0.05),肌糖原各时间点含量无显著性差异(P 0.05)。【结论】军曹鱼幼鱼在低氧胁迫后发生氧化损伤,刺激自身免疫系统,通过调整相关酶活力及能量代谢的方式提高其适应低氧的能力。     

2种乳酸菌对军曹鱼幼鱼生长及消化酶、免疫酶活性的影响

【目的】研究配合饲料中添加乳酸杆菌和粪肠球菌对军曹鱼幼鱼生长、消化酶和免疫酶活性的影响。【方法】在基础饲料中分别按1.0×10~8、3.0×10~8、5.0×10~8cfu/g单独喷洒乳酸杆菌和粪肠球菌两种菌,制作6种饲料,投喂初始体质量(10.66±0.09)g的健康军曹鱼幼鱼10周,以基础饲料为对照组,测定幼鱼生长性能、消化酶和免疫酶指标。【结果】与对照组比,乳酸菌组幼鱼饵料系数降低(P0.05),增重率和特定生长率呈现先升后降的变化趋势,并显著高于对照组(P0.05),乳酸杆菌添加组的增重率和特定生长率整体显著高于粪肠球菌添加组(P0.05),在3.0×10~8cfu/g乳酸杆菌添加组达到最大值;乳酸菌组的淀粉酶(AMS)、胰蛋白酶(TRY)和脂肪酶(LPS)活性均显著高于对照组(P0.05);两种乳酸菌添加组的超氧化物歧化酶(SOD)和溶菌酶(LZM)活性高于对照组,而丙二醛(MAD)活性显著低于对照(P0.05)。【结论】以喷洒方式在饲料中添加乳酸杆菌和粪肠球菌,可显著提高军曹鱼的生长性能、消化能力和非特异性免疫力,影响效果与添加量和添加乳酸菌种类有关,乳酸杆菌对军曹鱼的相关作用效果优于粪肠球菌,以3.0×10~8cfu/g乳酸杆菌的效果最佳。     

急性低氧胁迫对大规格军曹鱼幼鱼肝脏氧化应激、能量利用及糖代谢的影响

【目的】研究军曹鱼在急性低氧应激时肝脏代谢机能状态变化。【方法】测定急性低氧胁迫前后肝脏氧化应激指标、能量利用指标及糖代谢指标的变化。【结果】1)急性低氧胁迫后,军曹鱼肝脏超氧化物歧化酶(SOD)活性、谷胱甘肽过氧化物酶(GSH-Px)活性均降低,与胁迫前差异极显著(P0.01);脂质过氧化物(LPO)活性、丙二醛(MDA)含量均升高,与胁迫前差异极显著(P0.01);过氧化氢酶(CAT)活性略有降低,与胁迫前无显著性差异(P0.05)。2)急性低氧胁迫后,军曹鱼肝糖原(LG)含量、ATP酶活性均下降,与胁迫前差异极显著(P 0.01)。3)急性低氧胁迫后,军曹鱼肝脏乳酸脱氢酶(LDH)、丙酮酸激酶(PK)、己糖激酶(HK)活性均升高,与胁迫前差异极显著(P0.01)。【结论】急性低氧胁迫对军曹鱼幼鱼肝脏组织造成显著的氧化损伤,使肝脏氧化应激、能量利用及糖代谢相关指标发生显著变化。     

低盐胁迫对钝吻黄盖鲽幼鱼鳃Na~+/K~+-ATP酶、肝脏抗氧化酶和非特异免疫酶的影响

研究钝吻黄盖鲽(Pleuronectes yokohama)幼鱼鳃的Na~+/K~+-ATP酶(NKA)和肝脏的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)在低盐(6、18,分别记作S6、S18组)胁迫下的变化规律,探讨其适应盐度的规律,以及抗氧化机制和非特异免疫能力。结果显示,S6组和S18组鳃的NKA活力均呈先增后减的变化趋势,1 d时最大(P0.05),S6组7 d时开始下降,而S18组在3 d时开始下降。肝脏的SOD和CAT活力均先升后降,其中SOD活力S6和S18组均于7 d时最大(P0.05),14 d时S6组活力较S18组大;CAT活力S6和S18组均于7 d时最大(P0.05),在14 d时降至初始水平。肝脏ACP活力S6、S18组均于3 d时升至最高(P0.05),14 d时S18组降至对照组水平,而S6组则低于对照组(P0.05);AKP活力S6和S18组均呈现先升后降的变化,在3 d达到峰值,14 d时仍高于对照组(P0.05)。低盐胁迫影响钝吻黄盖鲽幼鱼的NKA、抗氧化酶和非特异免疫酶,S18组对盐度胁迫的适应能力更大。     

不良环境对溶藻弧菌胱硫醚-β-合成酶活力及抗氧化系统的影响

研究非适宜的p H、温度和盐度条件,以及抗生素胁迫和添加外源H2S条件下溶藻弧菌胱硫醚-β-合成酶(cystathionine-β-synthase,CBS)、超氧化物歧化酶(superoxide dismutase,SOD)和过氧化物酶(peroxidase,POD)的活力及谷胱甘肽(glutathione,GSH)含量的变化,分析CBS与抗氧化系统的相关性,探讨不良环境对CBS活性及抗氧化系统的影响。结果表明,在非适宜温度、盐度及抗生素胁迫下,溶藻弧菌的CBS活力均高于对照组,差异有统计学意义(P0.05)。在非适宜温度下,其SOD和POD的活力及GSH含量均有不同程度的提高(P0.05)。在非适宜盐度下,GSH含量上调(P0.05)。在红霉素和壮观霉素胁迫下,SOD和POD活力均上调(P0.05),而庆大霉素和四环素胁迫则分别提高SOD、POD活力(P0.05)。在非适宜p H条件下,低p H上调CBS、SOD和POD的活力及GSH含量(P0.05);高p H条件下CBS活力与对照组差异无统计学意义(P0.05),SOD活力较对照组下降(P0.05)。相关性分析发现,在不同温度、盐度条件下及抗生素胁迫下CBS活力与SOD、POD活力及GSH含量之间具有显著正相关(P0.05),而在不同p H条件以及抗生素+Na HS处理后,CBS活力与SOD、POD活力及GSH含量之间的相关性无统计学意义(P0.05)。溶藻弧菌可通过提高CBS活力以调节其抗氧化系统,从而抵御不良环境,而外源H2S则提高溶藻弧菌SOD活力和GSH水平以维持溶藻弧菌正常生理活动。     

低温胁迫对军曹鱼幼鱼脂代谢相关生理生化的影响

【目的】探讨低温胁迫对军曹鱼(Rachycentroncanadum)幼鱼脂代谢相关生理生化的影响。【方法】将军曹鱼幼鱼分别在自然水温(30.5±1.0)℃(对照)、(20.0±0.5)℃条件下养殖7 d,并在1、4、7 d时采集各组血清、肝脏、肌肉和腹腔脂肪(intraperitoneal fat, IPF),测定血清甘油三酯(triglycerides, TG)、总胆固醇(total cholesterol, T-CHO)、高密度脂蛋白(high-density lipoprotein, HDL)、低密度脂蛋白(low-density lipoprotein, LDL)、丙二醛(malondialdehyde, MDA)和总抗氧化能力(total antioxidant capacity, T-AOC)等生化指标,以及肌肉、肝脏和IPF的脂肪酸组成。以油红O染色切片观察肝脏组织。【结果】低温胁迫过程中,军曹鱼血清TG含量随胁迫时间的延长呈上升趋势;T-CHO呈先降后升再降的趋势;HDL在前4 d与对照组无显著差异,之后显著低于对照组;LDL 1 d时与对照组无显著差异,之后呈显著上升趋势;血清T-AOC在7 d内均呈下降趋势,MDA在显著上升后又呈下降趋势;肝脏组织油红O切片结果显示,有脂滴分布不均的现象;低温胁迫对军曹鱼肌肉脂肪酸组成的影响不显著,但可显著提高肝脏和IPF的多不饱和脂肪酸(Polyunsaturated fatty acid, PUFA)比例。【结论】低温胁迫导致军曹鱼幼鱼机体抗氧化能力降低并积累大量MDA,军曹鱼从提高血清TG含量、增加血清胆固醇含量(增加LDL、减少HDL)、调整肝脏和IPF中脂肪酸组成方面响应低温胁迫。     

盐度对仿刺参免疫指标的影响

【目的】研究不同盐度下对攻毒灿烂弧菌(Vibrio splendidus)前后的仿刺参免疫指标的影响。【方法】将平均体质量(6.16±1.86)g的仿刺参150头随机分为5组,分别置于盐度25、27、29、31、33的海水中暂养,注射200μL 3.98×10~8 CFU/m L致病菌V. splendidus,在0、6、12、24、48 h采集体腔液,测定相关免疫指标。【结果】攻毒前,各盐度下仿刺参超氧化物歧化酶(SOD)、酸性磷酸酶(ACP)、过氧化氢酶(CAT)、呼吸暴发力(RB)差异不显著(P 0.05)。仿刺参吞噬活力在盐度25、27、29、31条件下,随盐度的升高吞噬活力显著升高(P 0.05),盐度33条件下,仿刺参吞噬活力随盐度的升高而降低;仿刺参酚氧化物(PO)活力在盐度25、27、29条件下,随盐度的升高PO活力显著升高(P 0.05),盐度31、33条件下,仿刺参PO活力随盐度的升高而降低。攻毒后,仿刺参SOD活力变化明显,盐度25、27、33条件下,仿刺参SOD活力在48 h显著降低(P 0.05),盐度29、31条件下,攻毒后仿刺参SOD活力显著降低时间提前;仿刺参ACP活力变化明显,盐度25、27条件下,攻毒后仿刺参ACP活力在12 h显著升高(P 0.05),盐度29、31、33条件下,攻毒后仿刺参ACP活力在6 h显著升高(P 0.05);CAT活力无变化规律;盐度25、27条件下,攻毒后仿刺参吞噬活力在6 h显著升高(P 0.05),盐度29、31条件下,攻毒6、12、24、48 h后与0 h相比仿刺参吞噬活力无显著性差异(P 0.05);盐度对仿刺参RB有显著性影响(P 0.05),但无变化规律;攻毒后,不同盐度下的仿刺参PO活力在不同时间点较0 h均有升高,但没有规律性。【结论】盐度对仿刺参的吞噬活力、PO的影响,可以为选择适宜盐度水域养殖仿刺参提供依据;仿刺参在攻毒灿烂弧菌后SOD、ACP具有较高的敏感性。     

温度、盐度、pH和体质量对尼罗罗非鱼幼鱼窒息点的影响

利用实验生态学的方法研究不同温度(15、20、25、30和35℃)、盐度(0、5、10、15和20)、pH(5、6、7、8和9)和体质量(1.93±0.08、3.43±0.12、7.95±0.34、11.74±0.41和15.84±0.61 g)对尼罗罗非鱼幼鱼窒息点的影响,并建立温度、盐度、pH、体质量与罗非鱼窒息点间的回归方程。结果表明:温度t、盐度S、pH和体质量m对尼罗罗非鱼幼鱼窒息点有显著影响(P<0.05)。当温度、盐度、pH和体质量分别为25.28℃、3.6、8.06、6.3 g时,窒息点(DAP)最低,回归方程为DAP=0.000 9 t 2-0.045 5 t+0.726 6(R2=0.952 1),DAP=-0.000 1 S 3+0.004 2 S 2-0.023 9 S+0.111 9(R2=0.922 8),DAP=0.009 3 pH2-0.149 9 pH+0.7174(R2=0.976 8);DAP=-0.000 3 m3+0.011 1 m2-0.104 3 m+0.362 8(R2=0.948 4)。在溶氧不足情况下,温度25.28℃、盐度3.6、pH 8.06的环境条件有助于提高幼鱼耐低氧能力。     

饲料脂肪水平对红鳍东方鲀幼鱼肝脏抗氧化酶活力及组织结构的影响

以脂肪质量分数分别为5.77%、7.71%、8.93%、11.89%、13.75%、16.42%的饲料饲喂红鳍东方鲀(Takifugurubripe)幼鱼56 d,测定其肝脏抗氧化酶活力和总抗氧化能力,并对其肝脏、肠及肌肉进行组织学观察,研究不同饲料脂肪水平对红鳍东方鲀幼鱼肝脏抗氧化酶活力及组织结构的影响。结果表明,5.77%组过氧化氢酶(CAT)活力与其他各组间有显著性差异(P<0.05)。总抗氧化能力(T-AOC)活力的最高值出现在8.93%组,且显著高于其他各组(P<0.05)。饲料脂肪水平大于8.93%的实验组间超氧化物歧化酶(SOD)活力差异不显著(P>0.05),且显著低于8.93%组;5.77%、7.71%、8.93%组呈增加趋势,且各组间差异显著(P<0.05)。谷胱甘肽过氧化物酶(GSH-PX)活力的峰值出现在13.75%组,且显著高于其他各组(P<0.05),总体呈先增加后降低的趋势。组织学观察表明,5.77%、7.71%、8.93%组,虽然肝脏也有脂肪空泡存在,但是肝脏、肠和肌肉组织结构完整,无明显病变现象;11.89%、13.75%、16.42%组的肝脏、肠和肌肉均有不同程度的病变现象,各组间差别明显。由此认为,脂肪水平为8.93%组,抗氧化酶活力最高,该脂肪水平下的饲料对红鳍东方鲀幼鱼肝脏代谢最有利,组织结构完整无病变。     

Antioxidant enzyme activities in different genders and tissues of amphioxus Branchiostoma belcheri tsingtauense

Information regarding antioxidant enzymes in amphioxus remains lacking, and this study was carried out to examine the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) in different genders and tissues of amphioxus Branchiostoma belcheri tsingtauense. Results show that (1) CuZn-SOD, CAT and GPX activities in the whole amphioxus B. belcheri tsing- tauense were basically at the same levels in male and female amphioxus, whereas both T-SOD and Mn-SOD activities in male amphioxus were significantly higher than that in the female (P<0.05); (2) The testis had significantly higher T-SOD and CuZn-SOD activities than the ovary (P<0.05); (3) CuZn-SOD activity was undetectable in the guts of male and female amphioxus; (4) For both male and female am- phioxus, the activities of CAT and GPX in the gonads including testis and ovary were the lowest (P<0.05) among the tissues examined; (5) The gut and gill had the same level GPX activities while the gut had a higher CAT activity; (6) There was no clear difference in CAT and GPX activities in the corresponding tissues between male and female amphioxus. The study on SOD, CAT and GPX activities in different genders and tissues of the protochordate provides data for future comparison of amphioxus antioxidant enzymes with those of invertebrates and vertebrates.     

Effect of dietary supplementation of vitamin C on growth,reactive oxygen species,and antioxidant enzyme activity of Apostichopus japonicus (Selenka) juveniles exposed to nitrite

Different amounts of vitamin C were added to diets fed to juveniles(2.5 ± 0.15 g) of sea cucumber Apostichopus japonic u s(Selenka) in an attempt to reduce the stress response of specimens exposed to nitrite stress. A commercial feed was used as the control diet and three experimental diets were made by supplementing 1 000, 1 500, or 2 000 mg vitamin C/kg diet to control diet separately in a 45-day experiment. Sea cucumbers were exposed to three different levels(0.5, 1.0, and 1.5 mg/L) of nitrite stress for 4, 8, and 12 h at four time intervals(0, 15, 30, and 45 d). Growth of the animals was recorded during the experiment. Reactive oxygen species(ROS)(i.e. hydroxyl free radical(-OH), malondialdehyde(MDA) and total antioxidant capacity(T-AOC)) and antioxidant enzyme activities(i.e., superoxide dismutase(SOD) and catalase(CAT)) were measured. Response surface methodology(RSM) was used to analyze the effect of multiple factors on ROS indices and enzyme activities. Weight gain(WG) and special growth rate(SGR) of vitamin C supplementation groups were significantly higher than those of control group( P 0.05). The levels of-OH and MDA increased under exposure time extending and nitrite concentration increasing, whereas T-AOC level decreased. SOD and CAT activities increased at 4 h and 8 h and decreased at 12 h. During the days in which the animal consumed experimental diets, the levels of-OH and MDA decreased and that of T-AOC increased. This result suggests that diets containing vitamin C could reduce the nitrite stress response in the animals and increase their antioxidant capacity. The multifactor regression equation of growth performance, ROS indices, and duration of feeding results suggest that vitamin C supplementation of 1 400–2 000 mg/kg diet for 29–35 days could reduce effectively the effects of nitrite exposure.     

Salicylic acid and heat acclimation pretreatment protects Laminaria japonica sporophyte (Phaeophyceae) from heat stress

Possible mediatory roles of heat acclimation and salicylic acid in protecting the sporophyte of marine macroalga Laminaria japonica (Phaeophyceae) from heat stress were studied. Heat stress resulted in oxidative injury in the kelp blades. Under heat stress significant accumulation of hydrogen peroxide (H₂O₂) and malonaldehyde (MDA), a membrane lipid peroxidation product, and a drastic decrease in chlorophyll a content were recorded. Activity of the enzymatic antioxidant system was drastically affected by heat stress. The activity of superoxide dismutase (SOD) was significantly increased while peroxidase (POD), catalase (CAT) and glutathione peroxidase (GPX) were greatly inhibited and, simultaneously, phenylalanine ammonia-lyase was activated while polyphenol oxidase (PPO) was inhibited. Both heat acclimation pretreatment and exogenous application of salicylic acid alleviated oxidative damage in kelp blades. Blades receiving heat acclimation pretreatment and exogenous salicylic acid prior to heat stress exhibited a reduced increase in H₂O₂ and MDA content, and a lower reduction in chlorophyll a content. Pretreatment with heat acclimation and salicylic acid elevated activities of SOD, POD, CAT, GPX and PPO. Considering these results collectively, we speculate that the inhibition of antioxidant enzymes is a possible cause of the heat-stress-induced oxidative stress in L. japonica, and enhanced thermotolerance may be associated, at least in part, with the elevated activity of the enzymatic antioxidant system.     

Effects of dietary menadione on the activity of antioxidant enzymes in abalone, Haliotis discus hannai Ino

A 240-day growth experiment in a re-circulating water system was conducted to investigate the effects of dietary menadione on the growth and antioxidant responses of abalone Haliotis discus hannai Ino. Triplicate groups of juvenile abalone (initial weight: 1.19 ± 0.01 g; shell length: 19.23 ± 0.01 mm) were fed to satiation with 3 semi-purified diets containing 0, 10, and 1 000 mg menadione sodium bisulfite (MSB)/kg, respectively. Results show that there were no significant differences in the rate of weight gain or in the daily increment in shell length of abalone among different treatments. Activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione S-transferase (GST) and glutathione reductase (GR) in viscera were significantly decreased with dietary menadione. However, activities of these enzymes except for GPX in muscle were increased. Therefore, antioxidant responses of abalone were increased in muscle and decreased in viscera by dietary menadione.     

Antioxidant response of ridgetail white prawn <Emphasis Type="Italic">Exopalaemon carinicauda</Emphasis> to harmful dinoflagellate <Emphasis Type="Italic">Prorocentrum minimum</Emphasis> exposure and its histological change

The dinoflagellate Prorocentrum minimum, one of the most widespread red tide causing species, affects marine aquaculture and ecosystems worldwide. In this study, ridgetail white prawn Exopalaemon carinicauda were exposed to P. minimum cells (5 × 10⁴ cells mL^?1) to investigate its harmful effects on the shrimp. Antioxidant activities and histological changes were used as indicators of health status of the shrimp. In 72 hours, the mortality of E. carinicauda was not affected, but its antioxidant response and histology were statistically different from those of control. Elevated superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities and depressed catalase (CAT) activity were observed in gill; while increased SOD, glutathione S-transferase (GST), CAT activities and modulated GPX activity were observed in hepatopancreas. Thus, antioxidant activities in gill and hepatopancreas seem to respond differentially to harmful alga exposure. Increased malondialdehyde (MDA) content in early a few hours indicates the damage of the antioxidant defense system. Although MDA content recovered to a low level thereafter, a series of histological abnormalities including accumulation or infiltration of hemocytes, tissue lesions and necrosis were discovered in gill and hepatopancreas. Exposure to P. minimum induced sublethal effects on E. carinicauda, including temporary oxidative damage and histological injury.     

亚硝酸氮对红鳍东方[鱼屯]的毒性效应

采用半静水生物测试法,研究亚硝酸盐氮对红鳍东方[鱼屯]（Takifugu rubripes）（95～9．8g）的急性毒性及对部分肝脏抗氧化酶活性的影响。结果表明,在急性毒性实验中,亚硝酸盐氮对红鳍东方[鱼屯]的24、48、72和96h半致死质量浓度（LC50）分别为20188、19057、17109、15925mg／L,安全质量浓度为1592mg／L;在亚急性毒性实验中,当红鳍东方纯分别在5．3、106,159、212mg／L亚硝酸盐氮中暴露4周时,其肝脏总抗氧化能力（T—AOC）、超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性随亚硝酸盐氮浓度的升高均被显著抑制,差异有统计学意义（P〈0.05）,表明亚硝酸盐氮会对鱼体的抗氧化能力产生影响。     

Effects of temperature and salinity on the development of embryos and larvae of the veined rapa whelk Rapana venosa （Valenciennes, 1846）

The major population of the veined rapa whelk Rapana venosa(Valenciennes, 1846), which is an important fishery resource, is facing a large decline in China. We studied the effects of incubation temperature(16–34℃ at salinity 30) and salinity(5–45 at 25℃) on the incubation period and subsequent larval development. In the temperature experiment, the shortest incubation period was 12 days at 34℃, the lower temperature limit was 16℃, the longest mean shell length(1 193±17 μm) occurred at 25℃ and the highest survival rate 72.28%±5.62% was observed at 28℃. In the salinity experiment, the shortest incubation period was 15 days at 25. The salinity tolerance range was 15–40, the longest mean shell length(855±9 μm) and the highest survival rate 72.93%±4.85% were both observed at 35. This study demonstrated that, during the egg–mass stage, temperature and salinity regimes infl uence later growth and survival of larvae. These observations deepen our understanding of the ecology and conservation of natural populations of Rapana venosa.     

Variations of antioxidant enzyme activity and malondialdehyde content in nemertean Cephalothrix hongkongiensis after exposure to heavy metals

The antioxidant enzyme activity and malondialdehyde (MDA) content of Cephalothrix hongkongiensis were studied to assess variations in the biochemical/physiological parameters of nemerteans under heavy metal stress. Worms were exposed to copper, zinc and cadmium solutions at different concentrations, and the activity of three antioxidant enzymes, catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX), and MDA content were measured. The results show that the activity of each enzyme changed immediately after exposure to heavy metals. CAT was invariably inhibited throughout the experimental period, while the SOD activity was significantly elevated by exposure to Cu²⁺ for 48 h, but then decreased. SOD was inhibited by Zn²⁺during the first 12 h of exposure, but activated when exposed for longer periods. Under Cd²⁺ stress, SOD activity decreased within 72 h. GPX activity varied greatly, being significantly increased by both Cu²⁺ and Zn²⁺, but significantly inhibited by Cd²⁺ in the first 12–24 h after exposure. MDA content increased on Cu²⁺ exposure, but normally decreased on Zn²⁺ exposure. MDA content followed an increase-decrease-increase pattern under Cd²⁺ stress. In conclusion, the antioxidant system of this nemertean is sensitive to heavy metals, and its CAT activity may be a potential biomarker for monitoring heavy metal levels in the environment.     

Antioxidation and ATPase activity in the gill of mud crab Scylla serrata under cold stress

Mud crab (Scylla serrata) is an important commercial crustacean in China. An experiment was designed to study the effect of cold stress on S. serrata. After a one-week adaptation at 28oC, the temperature is suddenly reduced to 4oC. The crabs were sampled every 2 h for 10 h and dissected immediately to measure the enzyme activity. The crabs at room temperature (28oC) were used as the control group. The activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), the content of malondialdehyde (MDA) and the activity of 4 ATPases (Na , K -ATPase; Mg2 -ATPase; Ca2 -ATPase; Ca2 , Mg2 -ATPase) were measured biochemically. In contrast to the control group, the SOD activity increased significantly from 2 to 6 h after the cold stress, and then decreased. The CAT and GPX activities increased in 2 h, and then decreased gradually. The content of MDA increased gradually in 4 h. The activity of Na , K -ATPase decreased in 2 h, increased up to the top value at Hour 6, then decreased again. The activities of Mg2 -ATPase, Ca2 -ATPase and Ca2 , Mg2 -ATPase increased significantly in 6 h, insignificantly in any other hours. Under cold stress, the activity of antioxidative enzymes in S. serrata was reduced at first then stabilized, ROS-scavenging weakened, and MDA accumulated gradually in the gill after 6 h. The activity of the 4 ATPases in the crab decreased after 6 h, suggesting that the ability to regulate ion concentration has been paralyzed. Therefore, the maximum period to sustain healthy meat in the crab under cold stress is 6 hours.