热应激对银鲫生化指标和HSP70 mRNA表达的影响

本研究旨在探讨热应激对银鲫(Carassius auratus gibelio)生化指标及肝脏HSP70 mRNA表达的影响,选取平均体重为(72.8±10.1) g的银鲫,分别在热应激前(25℃,对照组)、热应激后(32℃,0 h、2 h、6 h、10 h)和恢复适温后6 h (25℃,恢复组)的条件下,测定机体血浆乳酸(LD)、血浆葡萄糖(Glu)、肝糖原(Gly)、己糖激酶(HK)、丙酮酸激酶(PK)和肝脏HSP70 mRNA表达量变化。研究表明,实验组乳酸含量从热应激开始至恢复期,差异始终不显著(P>0.05);实验组血浆葡萄糖水平在热应激后0 h、2 h、6 h,极显著高于对照组(P<0.01);实验组肝糖原水平在热应激0 h时,极显著高于对照组(P<0.01),其余时间点差异不显著(P>0.05);己糖激酶活力在热应激后2 h,显著高于对照组(P>0.05);丙酮酸激酶活力在热应激后6 h,极显著高于对照组(P<0.01);热应激后2 h,肝脏中HSP70 mRNA表达量达到最高(P<0.01),恢复至适温后,表达量与应激前无差异(P>0.05)。本研究为进一步探究银鲫的高温应激作用机制及调控机理提供参考数据,同时,也为银鲫养殖和育种等生产实践提供相应参考依据。     

大黄素、维生素C及其配伍对团头鲂生长、生理生化指标、抗病原感染以及两种HSP70s mRNA表达的影响

选取1200尾健康的团头鲂,体重为(133.44±2.11)g,随机分成4组,其中1组为对照组,投喂基础日粮(含50.3mg/kg维生素C,以L-抗坏血酸-2-多聚磷酸酯为Vc源),另外3组为试验组,投喂饲料是在基础日粮中分别添加60mg/kg大黄素、700mg/kgVc、60mg/kg大黄素+700mg/kgVc。连续投喂60d后,检测团头鲂生长、肌肉成分、血液和肝脏生化指标以及两种热休克蛋白70s(HSP70s)mRNA的表达水平,并统计团头鲂感染嗜水气单胞菌后的成活率,以综合评价大黄素、高剂量Vc及其配伍对团头鲂的作用效果。结果表明,与对照组相比,大黄素、Vc组显著提高了鱼体增重率和特定生长率,血清中总蛋白(TP)、溶菌酶(LSZ)和碱性磷酸酶(AKP)的水平,肝脏中超氧化物歧化酶(SOD)的活性和诱导型HSP70 mRNA的基础表达水平,降低了饵料系数、死亡率、血清中皮质醇(COR)、甘油三酯(TG)以及肝脏丙二醛(MDA)的含量(P<0.05);配伍组虽然血清中TP、LSZ的含量以及肝脏HSP70 mRNA水平显著升高,肝脏MDA的含量也显著降低(P<0.05),但均未表现出协同增效作用,其它指标与...     

草鱼PGC-1β基因克隆及高糖高脂饲料对其表达的影响

为探讨过氧化物酶体增殖物激活受体γ辅激活因子-1β(peroxisome proliferator-activated receptor-γ coactivator-1 beta, PGC-1β)基因在草鱼能量代谢中的作用,本研究克隆了草鱼PGC-1β基因的核心序列,并对其进行了生物信息学分析;利用Real-time PCR技术检测了PGC-1β在不同组织的表达状况;同时研究了饥饿、饥饿再投喂及高糖(糖含量45%)高脂(脂含量8%)饲料对草鱼肝胰脏PGC-1β表达的影响。结果显示,所获得的草鱼PGC-1β基因部分cDNA片段长为885bp(GenBank登录号为：KM580493.1),共编码293个氨基酸,与斑马鱼的同源性为81%;该基因在脑中的表达量最高,肠和肝胰脏次之;与正常投喂组相比,饥饿(7d)导致PGC-1β在肝脏中的mRNA水平显著升高(P<0.05),再投喂后几乎恢复到对照组的表达水平。饲喂高脂以及高糖高脂饲料(65d)后,与对照组相比,草鱼肝胰脏中PGC-1β的mRNA水平显著升高(P<0.05)。研究结果表明,PGC-1β基因在草鱼能量代谢旺盛的组织中高表达,同时饥饿处理、饲料糖和脂肪水平等营养状况显著影响PGC-1β mRNA的表达。以上提示,PGC-1β在草鱼能量代谢过程中可能起到重要作用。     

饲料碳水化合物水平及饥饿处理对斜带石斑鱼生长及葡萄糖耐受能力的影响

为揭示斜带石斑鱼对碳水化合物利用的特点,研究了3个碳水化合物水平及饥饿处理对其生长、血浆生化指标及肝/肌糖原的影响。实验选取300尾初重为(35±0.28)g的幼鱼,设置持续投喂高(35%,CH)、中(21%,CM)、低(7%,CL)3个碳水化合物水平组,以及持续投喂组(CM)、饥饿再投喂组(R,饥饿4周+投喂4周,投喂CM组饲料)、饥饿组(S)3个投喂模式组。饲养8周后饥饿24 h,以30 mg/100 g体质量腹腔注射葡萄糖研究其代谢反应。结果显示,增重率和特定生长率随饲料碳水化合物水平的增加而升高,但无显著差异,饲料系数以CL组最高。不同碳水化合物水平下,各组注射葡萄糖后1~3 h血糖水平达峰值,但CM组在6 h内迅速回到注射前水平;各组血浆胰岛素水平均先降后升,但CL组在3 h后急剧下降;各组肝糖原、血浆甘油三酯含量在注射后1 h内均显著上升。饥饿处理下,持续投喂组(CM)血糖水平在6 h时迅速恢复至注射前水平;CM组和R组血浆胰岛素在1 h内显著下降,但S组持续上升;CM组血浆甘油三酯含量在0~6 h内显著高于其他两组。研究表明,饲喂中等水平碳水化合物(21%)比较符合斜带石斑鱼糖耐受能力,而饥饿处理下则以持续投喂组糖耐受能力最强。     

丙氨酰—谷氨酰胺投喂方式对建鲤生长和抗急性拥挤胁迫能力的影响

以初始体质量为(33.52±0.17)g建鲤为研究对象,在室内单循环养殖系统中进行8周(w)生长试验,分别配制成添加0.0%(对照)和0.5%(试验)丙氨酰—谷氨酰胺(Ala-Gln)的等氮等能(35%CP、17 kJ/g)饲料,采用5种投喂方式:连续8 w投喂对照饲料(Ⅰ);试验饲料2 w间隔投喂(Ⅱ);前4 w投喂试验饲料,后4 w投喂对照饲料的间隔投喂(Ⅲ);前4 w投喂对照饲料,后4 w投喂试验饲料的间隔投喂(Ⅳ);8 w连续投喂试验饲料(Ⅴ)。养殖试验结束时,进行急性拥挤胁迫试验。探讨Ala-Gln投喂方式对建鲤生长和抗急性拥挤胁迫能力的影响。结果表明,Ala-Gln连续投喂和间隔投喂组的生长都显著高于对照组(P<0.05)。2 w间隔投喂的特定生长率都显著高于4 w间隔和连续8 w投喂的饲料组(P<0.05);前4 w间隔投喂组的特定生长率要显著高于8 w连续投喂组(P<0.05)。血清皮质醇和血糖分别在急性胁迫后恢复0和1 h时达到高峰,血清HSP70在胁迫后恢复1～12 h都保持较高水平,然后下降,胁迫后恢复48 h达到胁迫前的水平。各种投喂方式组的血糖和血清皮质醇含量都显著低于对照组(P<0.05)。胁迫后恢复期,血糖迅速升高幅度最小的是2 w间隔投喂组,最先恢复到胁迫前状态的是2 w间隔投喂组和前4 w投喂的4 w间隔投喂组。胁迫后恢复期,各投喂组的血清HSP70都显著高于对照组(P<0.05),胁迫后恢复48和72 h时,后4 w投喂的4 w间隔投喂组和连续8 w的投喂组的血清HSP70显著高于对照组(P<0.05)。     

饥饿和再投喂期间尼罗罗非鱼生长、血清生化指标和肝胰脏生长激素、类胰岛素生长因子-Ⅰ和胰岛素mRNA表达丰度的变化

在室内可控条件下,对尼罗罗非鱼[初始体质量(62.50±3.44)g]进行饥饿28d和随后再投喂21d的处理,于饥饿第0、7、14、21、28天和再投喂第14、21天进行采样分析,研究饥饿和再投喂期间尼罗罗非鱼生长、血清生化指标和肝胰脏生长激素(GH)、类胰岛素生长因子-Ⅰ(IGF-Ⅰ)和胰岛素(IN)mRNA表达丰度的变化。结果显示,与饥饿第0天相比,饥饿超过7d鱼体体质量显著降低(P<0.05),再投喂21d显著增加(P<0.05);肝体比随饥饿时间延长显著降低(P<0.05),恢复投喂后较饥饿时升高,但显著低于饥饿前水平(P<0.05)。在血清指标上,甘油三酯、血糖、碱性磷酸酶、谷草转氨酶和谷丙转氨酶均随饥饿时间延长而逐渐降低,恢复投喂后均有不同程度提高,但转氨酶活性显著低于饥饿前水平(P<0.05);饥饿和再投喂对血清总胆固醇、高密度脂蛋白胆固醇和低密度脂蛋白胆固醇无显著影响(P>0.05)。在激素方面,与饥饿第0天相比,饥饿使血清GH含量及其肝胰脏mRNA表达丰度显著升高,血清IGF-Ⅰ及其肝胰脏mRNA表达丰度降低,恢复投喂后两者均显著升高(P<0.05);INmRNA表达丰度在饥饿7~21d显著升高(P<0.05),饥饿第28天时无显著差异(P>0.05),再投喂后显著降低(P<0.05)。     

高碳水化合物水平日粮对异育银鲫生长、生理、免疫和肝脏超微结构的影响

为了探讨异育银鲫对日粮中高碳水化合物的利用,选用168尾异育银鲫,分成2组,一组为正常对照组,投喂35%碳水化合物(35%CHO)水平日粮;另一组为高糖试验组,投喂50%碳水化合物(50%CHO)水平日粮每组设3个重复。在控温的循环水系统中饲养10周后,测定鱼体生长指标、肌肉成分、肝糖元、血液生化指标和免疫指标。结果表明,高糖组(50%CHO)显著(P<0.05)降低了特定生长率、增重率,但是对饵料系数、肝体比、脏体比、鱼体肌肉成分等没有显著(P>0.05)影响;两组异育银鲫血浆总蛋白、甘油三酯、总胆固醇、血糖和肝糖原含量都没有显著差异(P>0.05);高糖组(50%CHO)肝脏丙二醛含量显著升高(P<0.05)、天门冬氨酸转氨酶显著降低(P<0.05),而肝脏超氧化物歧化酶、总抗氧化能力、丙氨酸转氨酶和碱性磷酸酶都没有显著变化(P>0.05)。试验还对两组异育银鲫肝细胞进行超微结构观察,发现高糖饲料引起了异育银鲫肝细胞中糖原和脂肪的沉积,并对细胞和细胞器的结构产生一定损伤。从本试验结果来看,异育银鲫可以耐受50%饲料糖含量,但是长期摄食50%碳水化合物日粮对其生长不利,并会引起一定程度肝脏功能和结构的损伤。     

大黄蒽醌提取物对罗氏沼虾高温下抗氧化能力与热应激蛋白70基因表达的影响

将罗氏沼虾随机分成5组,每组3个平行,每个平行1 000尾,第1组为对照组,投喂基础日粮;另外4组为试验组,在基础日粮中分别添加0.05%、0.1%、0.2%、0.4%大黄蒽醌提取物。饲养10周后,对罗氏沼虾进行连续35 ℃高温应激48 h,测定肝胰腺总抗氧化能力、过氧化氢酶、超氧化物歧化酶、丙二醛、一氧化氮以及应激蛋白70的mRNA相对含量变化。结果表明:应激前,0.05%组显著提高了肝胰腺过氧化氢酶活性、超氧化物歧化酶活性,显著降低了肝胰腺丙二醛含量;0.2%试验组显著增加了肝胰腺总抗氧化能力、一氧化氮浓度,显著降低了肝胰腺丙二醛含量;0.10%、0.2%试验组显著增加HSP70 mRNA的相对含量;高温应激后,各组肝胰腺总抗氧化能力、过氧化氢酶活性、超氧化物歧化酶活性、一氧化氮浓度呈现降低趋势,其中0.1%和0.2%大黄蒽醌提取物相对较高,对照组较低;肝胰腺丙二醛含量呈现增加趋势,其中加0.1%和0.2%大黄蒽醌提取物比对照组低。应激6 h后0.1%和0.2%大黄蒽醌提取物组的HSP70 mRNA的相对含量仍比对照组高。因此添加0.1%和0.2%大黄蒽醌提取物提高了虾的抗氧能力,促进HSP70 mRNA的相对含量,对高温应激有一定的保护作用。     

禁食对大口黑鲈生长和肝脏IGF-I mRNA表达丰度的影响

运用实时荧光定量PCR技术,研究禁食对体质量为(100+1)g的1龄大口黑鲈(Micropterus salmoides)的生长和肝脏中类胰岛素生长因子-I(IGF-I)mRNA表达丰度的影响.在为期6周的实验期间,对照组每天表观饱食投喂2次;禁食组禁食3周后恢复投喂3周.实验期间对照组鱼体质量和体长逐渐增加.6周后,对照组鱼体增重率为10.99%,体长增加率为3.07%.禁食组禁食3周期间,鱼体质量下降了5.08%、体长减少了1.79%.同时肝组织IGF-I mRNA表达水平呈下降趋势,禁食结束时仪为对照组的29.93%.恢复投喂2周后肝组织IGF-I mRNA的表达量仍显著低于对照组(P＜0.05),鱼体质量为实验初始水平的98.54%,体长为实验初始水平的99.03%;恢复投喂3周后,禁食组鱼体质量、体长恢复到实验初始时水平(P＞0.05),但仍与对照组有显著差异(P＜0.01);肝组织IGF-I mRNA的表达丰度与对照组无显著性差异(P＞0.05).结果显示,禁食使大口黑鲈体质量、体长下降,同时肝组织IGF-I mRNA表达丰度也随之降低;而恢复投饲后,其生长、肝脏IGF-I mRNA的表达丰度也逐渐恢复.研究表明,鱼类的营养状况、生长和与IGF-I mRNA的表达之间存有正相关关系.     

卤虫无节幼体的营养强化对半滑舌鳎稚鱼生长、消化酶及相关激素水平的影响

通过投喂经蛋氨酸及裂壶藻强化的卤虫,研究其对半滑舌鳎稚鱼(初始体长1.67±0.14cm)生长性能、主要消化酶活性(淀粉酶、胃蛋白酶、类胰蛋白酶)、碱性磷酸酶活性及胆囊收缩素(CCK)、甲状腺素(T4)、三碘甲状腺原氨酸(T3)和皮质醇浓度的影响.试验设3个实验组(蛋氨酸组、裂壶藻组和蛋氨酸加裂壶藻组),分别投喂经蛋氨酸、裂壶藻及蛋氨酸十裂壶藻强化的卤虫,对照组投喂未经强化的卤虫.试验进行16d,每4d取样1次.结果显示,裂壶藻组的体长和体重在试验结束时处于最高水平,体重显著高于对照组(P＜0.05),体长在12d时显著高于其他组(P＜0.05).裂壶藻组碱性磷酸酶活力在16d时显著高于蛋氨酸组和对照组,类胰蛋白酶活力在16d时显著高于其他组(P＜0.05),T3含量在12d时显著高于蛋氨酸组及对照组,T4水平在12d时显著高于对照组(P＜0.05).蛋氨酸加裂壶藻组淀粉酶活力在12d时显著高于蛋氨酸组(P＜0.05).对照组的CCK含量在4d时显著高于蛋氨酸组和蛋氨酸加裂壶藻组(P＜0.05),12d显著高于3个实验组,16d时显著高于裂壶藻组(P＜0.05).蛋氨酸组的皮质醇含量在4d时显著低于其他3个试验组(P＜0.05),8d和16d时显著低于对照组及蛋氨酸加裂壶藻组(P＜0.05).其碱性磷酸酶、淀粉酶活力及T4和T3水平在试验前期都较高,说明蛋氨酸强化的卤虫投喂对半滑舌鳎稚鱼的生长及激素水平有较微弱的促进作用,可能是由于卤虫无节幼体含有的蛋氨酸基本可以满足鱼体生长需要.     

Effects of a probiotic bacterial <Emphasis Type="Italic">Lactobacillus rhamnosus</Emphasis> dietary supplement on the crowding stress response of juvenile Nile tilapia <Emphasis Type="Italic">Oreochromis niloticus</Emphasis>

To test the effects of probiotic bacteria against crowding stress, juvenile Nile tilapia Oreochromis niloticus were fed commercial feed supplemented with 1 × 10¹⁰ cfu/g pellets of Lactobacillus rhamnosus for 3 weeks. The fish were confined and subjected to crowding for 7 and 14 days after which their physiological condition was investigated. The administration of probiotic prophylaxis improved growth performance even in the stressed fish. After 7 days of stress exposure, fish receiving probiotic-supplemented feed showed proactive behavior and coping responses to the stressor, as evidenced by elevated plasma glucose levels and osmolality, stabilized plasma electrolytes, and a higher RNA:DNA ratio. Fish stressed for 7 days and fed normal commercial diet showed impairment of plasma electrolytes; after 14 days, the plasma osmolality, electrolytes, glucose, and RNA:DNA ratio decreased, indicating physiological maladaptation to the stressor. The growth rate was also found to be reduced, suggesting that energy demand exceeded the energy available from metabolism and dietary uptake. This latter effect was not observed in fish fed the probiotic-supplemented diet. The results suggest that probiotic bacteria prophylaxis may increase energy availability for metabolic support of the crowding stress response and improve the stress coping capacity of fish.     

<Emphasis Type="Italic">Aloysia triphylla</Emphasis> in the zebrafish food: effects on physiology,behavior, and growth performance

Dietary supplements are commonly used by animals and humans and play key roles in diverse systems, such as the immune and reproductive systems, and in metabolism. Essential oils (EOs), which are natural substances, have potential for use in food supplementation; however, their effects on organisms remain to be elucidated. Here, we examine the effects of dietary Aloysia triphylla EO supplementation on zebrafish behavior, metabolism, stress response, and growth performance. We show that fish fed diets containing A. triphylla EO presented an anxiolytic response, with reduced exploratory activity and oxygen consumption; no changes were observed in neuroendocrine stress axis functioning and growth was not impaired. Taken together, these results suggest that the A. triphylla EO supplementation is a strong candidate for use in feed, since it ensures fish welfare (anxiolytic behavior) with decreased oxygen consumption. This makes it suitable for use in high-density production systems without causing damage to the neuroendocrine stress axis and without growth performance being impaired.     

Nutrition and feeding research in the spotted rose snapper (<Emphasis Type="Italic">Lutjanus guttatus</Emphasis>) and bullseye puffer (<Emphasis Type="Italic">Sphoeroides annulatus</Emphasis>), new species for marine aquaculture

The spotted rose snapper (Lutjanus guttatus) and bullseye puffer (Sphoeroides annulatus) are fish species from the tropical Eastern Pacific for which controlled production of larvae and juveniles has been accomplished in recent years. Diverse topics relating to their biology and aquaculture production are currently under study, in particular the nutrition and feeding aspects required to formulate practical feeds and rearing protocols. Improvements in larval growth and survival are possible by feeding live food organisms with natural or enhanced essential fatty acids content and highly digestible artificial microdiets. The ontogeny of the digestive tract and the expression and activity of digestive enzymes have been described for S. annulatus larvae. The effect of various protein and lipid levels on growth and feed utilization has been studied in juvenile and on-growing fish. Both species have carnivorous feeding habits and require high levels of protein in their diets, from 40% to 45% (dry weight) in spotted rose snapper and above 50% in bullseye puffer, with the younger stages requiring the highest protein levels. Encouraging results have been obtained in feeding experiments with different sources of dietary protein from animal and plant origin to evaluate their suitability as feed ingredients in practical diets. Optimization of fish culture practices through feeding management has also been investigated. Trials with various fish densities and feeding frequencies in intensive culture systems are providing information to improve feed utilization and growth in on-growing fish. Further research is underway to evaluate factors in broodstock nutrition which have an impact on egg and larval quality, and into the use of various commercially available oil sources in on-growing diets. In this paper, the results on nutrition and feeding research with both species are reviewed and research needs to support their commercial production in the region are discussed.     

In‐stream structure alters density‐dependent fish effects in stream ecosystems

The independent effects of in‐stream structure (ISS) and fish foraging on stream properties have been well documented, but few studies have explored the interactive effects of ISS and fishes on streams. Herein, we tested the independent and interactive effects of ISS and a generalist fish (Blacktail shiner, Cyprinella venusta) on suspended organic matter (SOM), benthic algae, invertebrate density and fish growth using experimental mesocosms. We found that Blacktail shiner foraging affected all of the ecosystem properties; however, in some cases, the fish effects differed between mesocosms with and without ISS. Specifically, mesocosms with ISS provided greater surface area for invertebrate colonisation and enhanced food resources for Blacktail shiner. As a result, benthic foraging by Blacktail shiner was reduced in these mesocosms. The reduced benthic foraging in turn enhanced benthic algae and benthic invertebrates via a bottom‐up, nutrient excretion pathway. The ISS‐dependent effects of fish on these stream properties, however, were only evident at low and intermediate fish densities (1 and 2 fish·m^?2 respectively). This was likely because at the highest fish density (4 fish·m^?2) intense fish foraging overrode any mediating effects of ISS. Furthermore, fish growth decreased with fish density because of intraspecific competition, but this negative effect on growth was reduced in mesocosms with ISS because of the increased forage base. However, the positive effect on fish growth was weak and only marginally significant. Our data suggest that fish‐mediated effects on streams are context dependent, changing with microhabitat availability (e.g. ISS) and density of the fish population.     

Effect of dietary water on growth of dentex <Emphasis Type="Italic">Dentex dentex</Emphasis>

ABSTRACT:   This study is concerned with the effect of hyrdated diets on growth and feed performance of Dentex dentex . Three levels of dietary water were tested: 7%, 20% and 40%. For the 7% level a commercial feed was used and the 20% and 40% water levels were obtained after adding an appropriate amount of deionized water to the commercial feed and mixing the pellets well. The diets were offered to fish by self-feeders, by which fish were allowed continuous access to diets after activating the self-feeders; by belt feeders, by which the diets were fed continuously and in excess over a 12 h interval; and by hand to apparent satiation two times a day. After 151 days of feeding, the group fed on the 20%-water diet showed significantly ( P  < 0.05) higher growth rate than the 7 and 40% groups, while no significant differences were observed in feed conversion rate or daily feed consumption. The means of feed delivery did not influence growth rate. Self-feeder, belt and hand feeding all gave comparable growth. Fish fed the more condensed 7%-water diet had smaller stomachs than fish fed the larger volume 40%-water diet. In the stomach, all groups of fish hydrated their digesta within 2 h after feeding to a moisture content of around 60%. Apparently no difference in digestive process was observed between groups. It was concluded that the addition of water in diet at the level of 20% has a beneficial effect on dentex growth.     

Black soybean seed coat containing diet enhancing the growth performance of juvenile hybrid tilapia Orechromis nitoticus × O. aureus

Black soybeans contain high amount of antioxidant, such as phenolic compounds and anthocyanins, in their seed coat. This study aimed to investigate the beneficial effect of black soybean seed coat (BSSC) on the growth of juvenile hybrid tilapia. There were four experimental diets: casein based diet (the control diet), casein based diet with 20% BSSC, and soybean and black soybean based diets. The results showed that after 8 weeks feeding period, BSSC meal increased 16% of the weight gain in the fish. When soybean and black soybean were used to replace casein as the main protein source, the diets resulted in poor growth performance and feed utilization and induced oxidative stress in the fish. It was suggested that oxidative stress induced by soybean based diets was due to the anti‐nutritional factors presented in the soybean and black soybean.     

Immunostimulatory effects of dietary poly‐β‐hydroxybutyrate in European sea bass postlarvae

The stable production of high‐quality fry in marine aquaculture is still hampered by unpredictable mortality caused by infectious diseases during larval rearing. Consequently, the development of new biocontrol agents is crucial for a viable aquaculture industry. The bacterial energy storage compound poly‐β‐hydroxybutyrate (PHB) has been shown to exhibit beneficial properties on aquatic organisms such as enhanced survival, growth, disease resistance and a controlling effect on the gastrointestinal microbiota. However, the effect of PHB on the developing immune system of fish larvae has so far not been investigated. In this study, the effect of feeding PHB‐enriched Artemia nauplii on survival, growth and immune response in European sea bass (Dicentrarchus labrax) postlarvae was examined. Amorphous PHB was administered to 28‐day‐old sea bass postlarvae over a period of 10 days. The survival and growth performance were monitored, and the expression of 29 genes involved in immunity, growth, metabolism and stress‐response was measured. While the expression of the insulin‐like growth factor 1 (igf1), an indicator of relative growth, was upregulated in response to feeding PHB, the larval survival and growth performance remained unaffected. After 10 days of PHB treatment, the expression of the antimicrobial peptides dicentracin (dic) and hepcidin (hep) as well as mhc class IIa and mhc class IIb was elevated in the PHB fed postlarvae. This indicates that PHB is capable of stimulating the immune system of fish early life stages, which may be the cause of the increased resistance to diseases and robustness observed in previous studies.     

银鲳ghr和igfbp1基因表达特征、组织分布及操作胁迫对其的影响（英文）

为探讨急性操作胁迫对银鲳生长的影响,首次克隆了3种生长调控相关基因-生长激素受体1(ghr1)、生长激素受体2(ghr2)和胰岛素样受体1(igfbp1),并对3种基因在银鲳肝脏、心脏、性腺、肌肉和肾脏等不同组织中的表达进行了比较。定量表达结果表明3种基因均广泛分布于所研究的各个组织中,而其中肾脏、性腺和心脏中的表达量较其它组织低。在银鲳受到外界操作胁迫刺激后,3种基因呈现不同的表达模式:其中ghr2和igfbp1的表达下调,而ghr2的表达量与对照组无显著性差异。结果表明,ghr2和igfbp1在银鲳生长调节中起到重要的作用;在胁迫环境中,外界刺激可通过下调生长相关基因表达以影响鱼体的生长。     

Dietary supplementation of yeast (<Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>) improves growth,stress tolerance,and disease resistance in juvenile Nile tilapia (<Emphasis Type="Italic">Oreochromis niloticus</Emphasis>)

The yeast Saccharomyces cerevisiae is one of the commonest probiotics incorporated in aquafeeds. An 84-day feeding trial was conducted to evaluate the effects of varying dietary inclusions of S. cerevisiae, 0% (control), 3% (YF3), 5% (YF5), and 7% (YF7), on growth, stress tolerance, and disease resistance in juvenile (body mass ~?21 g) Nile tilapia (Oreochromis niloticus). Fish were randomly distributed in groups of 20 into 12 1-m³ hapas and fed isoenergetic (~?17 kJ g^?1 gross energy) and isonitrogenous (~?300 g kg^?1 crude protein) diets at 3% of their bulk weight daily. Specific growth rates were significantly higher for the yeast-fed fish (0.77–0.78% day^?1) than for the control fish (0.60% day^?1) and resulted in significantly higher mean final weights for the yeast-treated groups. Protein and lipid retention efficiencies were also significantly higher in the yeast-fed fish than in the control group. In subsequent stress challenge trials, the yeast-fed fish had greater tolerance to acute heat as well as hypoxia exposure than the control fish. Survival rates of the yeast-treated groups following sudden exposure to elevated water temperature (40 °C) ranged from 82.5 to 100% compared to 15% for the control. Mean survival rates following a 24-h hypoxia exposure were also generally significantly higher for the yeast-fed fish. The probiotic groups recorded a relative percent survival (RPS) of 75% after a 14-day Aeromonas hydrophila infection challenge. The results of this study indicate that S. cerevisiae as an additive in Nile tilapia diets has beneficial impacts on growth, stress tolerance, and disease resistance.