3种品系尼罗罗非鱼生长及高密度胁迫后生理响应变化的比较

以‘吉富’、‘新吉富’、‘埃及尼罗’3种不同品系尼罗罗非鱼(Oreochromis niloticus)为研究对象, 通过不同品系之间生长与高密度胁迫反应的比较, 探讨3种尼罗罗非鱼的生长特点与应激后生理响应的变化规律。将初始规格基本一致的3种品系尼罗罗非鱼饲养100 d后, 吉富罗非鱼特定生长率最高, 新吉富其次, 两者间无显著差异(P>0.05), 埃及尼罗罗非鱼特定生长率显著低于吉富罗非鱼(P<0.05)。吉富与新吉富罗非鱼的内脏比显著高于埃及尼罗(P<0.05); 3种尼罗罗非鱼的肥满度之间无显著差异(P>0.05)。养殖实验结束后, 进行48 h的急性高密度(100 g/L)应激实验。应激48 h内, 吉富与新吉富罗非鱼血清总蛋白、葡萄糖、谷草转氨酶、胆固醇与溶菌酶活力/水平以及肝HSP70mRNA水平呈先上升后下降的变化。应激48 h后, 埃及尼罗罗非鱼血清皮质醇水平与应激前相比无显著差异(P>0.05), 吉富与新吉富罗非鱼的皮质醇水平显著高于应激前(P<0.05); 埃及尼罗罗非鱼血清溶菌酶活力与肝HSP70 mRNA水平在应激后48 h内始终高于应激前(P<0.05)。研究结果表明, 短期高密度胁迫可提高3种尼罗罗非鱼血清葡萄糖与甘油三酯的利用, 并诱发肝损伤。埃及尼罗罗非鱼的抗高密度应激能力高于吉富和新吉富罗非鱼。

     

尼罗罗非鱼铁调素调节蛋白在宿主抵御病原菌侵染和调节铁稳态中的功能

为了研究铁调素调节蛋白(hemojuvelin,HJV)在硬骨鱼中抵御病原菌感染和维持自身铁稳态过程中的作用,实验扩增了尼罗罗非鱼铁调素调节蛋白基因(Onhjv)的开放阅读框(ORF),分析其在健康尼罗罗非鱼各组织中的分布模式及在抵御病原菌感染和调节铁稳态中的相关作用。结果显示,Onhjv的ORF全长由1 248个碱基组成,编码415个氨基酸,在不同物种之间具有一定的保守性。实时荧光定量PCR(qRT-PCR)结果显示,Onhjv在尼罗罗非鱼各组织中广泛分布,并在肝脏中的表达量最高。在无乳链球菌或嗜水气单胞菌感染后,Onhjv在肝脏、脾脏、肠和鳃中的表达量均显著上调。体外头肾单核/巨噬细胞和肝细胞中Onhjv表达量在受到这2种病原菌应激下也显著上调。此外,在1和10μmol/L FeCl_3溶液刺激后,Onhjv表达量在肝脏、脾脏、肠和鳃等组织,以及头肾单核/巨噬细胞和肝细胞中的表达量也呈显著上调。受重组罗非鱼IL-6蛋白[(r)OnIL-6]刺激后,头肾单核/巨噬细胞中Onhjv表达量显著上调,表明炎症因子可以促进Onhjv表达。研究表明,尼罗罗非鱼铁调素调节蛋白在宿主抵御病原菌感染和维持铁稳态的过程中发挥作用。本实验为探究HJV在硬骨鱼中的生物学功能提供了参考,同时为进一步研究铁代谢在宿主防御病原菌感染过程中的重要作用提供理论指导。     

罗非鱼质量安全风险研究

目前中国针对罗非鱼(Oreochroms mossambcus)出口产品的质量安全监测系统尚不完善,建立罗非鱼质量安全评价标准、评估影响罗非鱼食品安全的因素,对于建立罗非鱼安全防控模式具有重要意义。本研究以罗非鱼的质量安全作为研究目标,通过对苗种培育、养殖环境及水产品流通等环节可能产生的风险事件的识别,建立罗非鱼质量风险评估体系。文章介绍了罗非鱼质量安全的总体概况,并分析了种苗、渔药、养殖生态及产品流通等影响罗非鱼质量安全的风险因素,并针对相关质量安全问题提出相应解决措施。本研究旨在促进罗非鱼产业的高质量发展,有助于为中国水产品的系统监测、评估体系建立提供参考。     

奥尼罗非鱼及其亲本的微卫星分析

运用SSR技术对奥利亚罗非鱼（Oreochromis aureus♂）、尼罗罗非鱼（Oreochromis niloticus♀）及其杂交子代（O．aureus♂×O．niloticus♀）的遗传多样性进行了研究。从12对微卫星引物中筛选出8个微卫星特异性位点,其中奥利亚罗非鱼（♂）特异位点7个;尼罗罗非鱼（♀）5个;杂交子代6个。利用这8个位点检测3个群体的遗传结构,共检测到63个等住基因,平均等位基因2．4394个,奥利亚罗非鱼（♂）、尼罗罗非鱼（♀）和杂交子代的平均观测杂合度分别为O．7083、0．9015和0．9787;平均期望杂合度分别为0．5341、0．5761和0．6435,平均多态信息含量（PIC）分别为0．4133、0．4693和0．5584。结果表明,3个群体的遗传多样性水平都较高,其中杂交子代群体的遗传多样性水平最高,奥利亚罗非鱼群体遗传多样性最低;基于Nei＇s遗传距离的聚类分析显示尼罗罗非鱼（♀）和杂交子代的遗传距离较近。     

饲料中添加谷胱甘肽对吉富罗非鱼抗氧化和抗亚硝基氮应激能力的影响

选择初始体重(3.27±0.04)g的吉富罗非鱼(GIFT Oreochromis niloticus),分别投喂基础饲料和添加80、160、240、320和400 mg/kg谷胱甘肽(GSH)的试验饲料,记作G0、G80、G160、G240、G320和G400。49 d后,G320血清和G160、G240肝脏谷胱甘肽S-转移酶,G160、G240血清和G320肝脏谷胱甘肽还原酶,G240肝脏超氧化物歧化酶,G320血清和G240肝脏过氧化氢酶活性,G240～G400血清和G240肝脏总抗氧化能力,G320血清抗超氧阴离子活性,与对照组相比分别显著升高。G80～G320肝脏丙二醛含量显著低于对照组。在亚硝基氮应激96 h内,G320累积死亡率显著降低。结果表明,饲料中添加一定量的GSH能显著提高罗非鱼的抗氧化性能和抗亚硝基氮应激能力。     

壳寡糖对吉富罗非鱼幼鱼生长性能、前肠组织结构及肠道主要菌群的影响

选用初始体质量(3.02±0.16) g的吉富罗非鱼幼鱼(Oreochromis niloticus)450尾,随机分为5组,每组3个重复,每重复30尾实验鱼,分别饲喂添加壳寡糖质量分数为0.00%(对照组)、0.10%、0.30%、0.50%和0.70%的饲料8周,考查壳寡糖对吉富罗非鱼幼鱼生长性能、前肠组织结构及肠道主要菌群的影响.结果表明,在生长性能方面,添加0.30%、0.50%和0.70%壳寡糖组增重率分别较对照组显著提高12.53%、16.17%和9.47%(P<0.05);添加壳寡糖各组较对照组饲料系数显著降低,饲料干物质和蛋白质的表观消化率均显著升高(P<0.05).在肠道组织结构方面,与对照组相比,添加0.30%和0.50%壳寡糖组的幼鱼前肠绒毛长度显著增加了18.02%和23.21%,宽度显著增加了45.21%和54.06%,密度显著增加了15.18%和19.37%(P<0.05);添加0.30%、0.50%和0.70%壳寡糖组的幼鱼肠壁厚度较对照组分别减少了16.41%、19.96%和15.00%(P<0.05).在肠道主要菌群方面,各壳寡糖添加组大肠杆菌数量均显著降低,乳酸杆菌数量显著增加(P<0.05).上述结果表明,吉富罗非鱼幼鱼饲料中添加壳寡糖可提高其生长性能,并改善肠道内环境,推荐适宜添加量为0.30%~0.50%.     

基于P-糖蛋白基因表达评价尼罗罗非鱼体内恩诺沙星代谢“首过效应”

为从药物酶的角度建立一种客观评价鱼类"首过效应"的方法,利用荧光定量PCR法测定尼罗罗非鱼(Oreochomis niloticus Linn)肝、肾组织中P-糖蛋白(P-gp)基因表达量,分析了单剂量(40 mg.kg 1)口服给药恩诺沙星(enrofloxacin,ENR)后,尼罗罗非鱼肠道、肝组织中mRNA水平的相对表达量与ENR血药浓度的时实相关性。实验结果显示:在尼罗罗非鱼肠道、肝组织中,P-gp基因在分子量127 bp处出现了与预期大小相符的特异性扩增片段。对尼罗罗非鱼口灌给药ENR后,ENR能迅速通过肠道进入血浆,其在肠道、肝和血浆中的消除速度较快,其药物时量曲线关系符合一级吸收的二室开放动力学模型。当血浆中ENR浓度达到最高达峰时(1 h),实验组肠道和肝中P-gp基因的相对表达量相对于对照组均表现出显著性差异(P<0.05);当肠道中ENR浓度达到最高峰时(2 h),实验组肠道P-gp基因的相对表达量则表现出极显著差异(P<0.01);当肝中ENR浓度达到最高峰时(2 h),实验组肝P-gp基因的相对表达量与对照组相比则表现出显著性差异(P<0.05)。该结果证实了鱼类P-gp基因参与药物代谢过程,提供了一种从分子水平揭示水产动物体内药物代谢规律的思路。     

Effects of Yeast Oligosaccharide Diet Supplements on Growth and Disease Resistance in Juvenile Nile Tilapia,Oreochromis niloticus

Commercially available yeast and yeast subcomponents consisting mainly of β-glucan or oligosaccharide feed additives were added to diets of juvenile (12–18g) Nile tilapia (Oreochromis niloticus) at rates recommended by suppliers. Three experiments were conducted following a basic protocol with varied rates of supplementation, duration of feeding, and stocking densities. Experimental diets were fed twice daily to apparent satiation for a period of two or four weeks, at the end of which feed consumption and weight gain were measured. Following the experimental feeding period, serum components, including protein and immunoglobulin concentrations, as well as lysozyme and complement activities, were measured. A disease challenge was conducted with pathogenic isolates of Streptococcus iniae or Edwardsiella tarda. Weight gains were not significantly different in fish fed the supplemented diets when compared to the control diet. There were significant differences in fed intake within individual experiments; however, this effect was not consistent in all three experiments. Overall feed efficiency was not significantly affected by diet. There were no differences in serum components of fish sampled at two or four weeks. Fish fed the experimental diets did not have lower mortality or morbidity after disease challenge compared to fish fed the control diets. Specific antibody against S. iniae or E. tarda measured by ELISA did not reveal differences in the fish surviving the challenge. We conclude that the incorporation of these commercial yeast component products into the diet of juvenile Nile tilapia at these rates and for these feeding periods had no effect on growth, serum components, antibody responses, or survival following S. iniae or E. tarda infection.     

Effects of Diet and Organic Fertilization on Water Quality and Benthic Macroinvertebrate Populations in Ponds Used to Culture Freshwater Prawn,Macrobrachium rosenbergii

ABSTRACT

Effects of three diets: (1) complete diet; (2) supplemental diet (vitamin and mineral supplements not added); and (3) the supplemental diet with an adjunct organic fertilization regimen (using distiller's dried grains with solubles [DDGS]) on benthic macroinvertebrate populations and water quality in experimental ponds used to culture freshwater prawns, Macrobrachium rosenbergii were investigated. Benthic samples were taken from deep (1.5 m) and shallow (1.0 m) areas of each of nine 0.02-ha ponds every three weeks, using a 0.09-m² Ekman dredge. The abundance of gastro-pods, oligochaetes, total non-insects, chironomids, total dipterans, total insects, and total macroinvertebrates was significantly higher (P <0.05) in ponds receiving the complete diet, possibly due to lower predatory pressure by prawns or direct benefits of micronutri-ents. Total macroinvertebrate abundance was significantly decreased (P <0.05) in ponds receiving supplemental diet (with and without organic fertilization), possibly due to increased predation by prawns to supplement the nutrition not provided by the lower quality diet. Organic fertilization significantly increased (P <0.05) the abundance of oligochaetes and total macroinvertebrates. These data suggest that M. rosenbergii can adjust to reduced feed quality by increasing consumption of benthic fauna.     

Evaluation and Nutrient Quality of Detoxified Jackbean Seeds,Cooked in Distilled Water or Trona Solution,as a Substitute for Soybean Meal in Nile Tilapia,Oreochromis niloticus,Diets

ABSTRACT

Jackbean, Canavalia ensiformis, seeds were detoxified using eight different wet thermal detoxification methods in either distilled water (5% w/v) or trona (NaCO₂.NaHCO₃.2H₂O) solution. The effects of the detoxification methods on hemagglutinating, antitryptic and urease activities, and on the digestibility coefficient of crude protein and gross energy in the jackbean seeds were investigated. Cracked jackbean seeds cooked (100°C) in trona solution for one hour proved to be more effective as a method of inactivating the antinutritional factors in jackbean seeds. Dried detoxified jackbean seed meals were incorporated in dry practical diets providing 20% or 30% of total protein and fed to Nile tilapia, Oreochromis niloticus, fingerlings (mean weight, 6.7 g) twice daily to apparent satiation for 70 days. Mortality was low and no abnormal fish behavior was noted even when the detoxified jackbean meals provided 30% of total protein in diet. Growth and feed utilization indices, were similar (P > 0.05) between the diet in which cracked jackbean seeds cooked in water provided 20% of total protein and in diets in which cracked jackbean seeds cooked in trona solution provided 20% or 30% of total protein. Carcass composition and hepatosomatic index showed no definite trend among O. niloticus fingerlings fed the experimental diets.