超声波对尼罗罗非鱼幼鱼生长的影响

选择尼罗罗非鱼Tilapia nilotica幼鱼(平均体重为1.95 g±0.60 g)为试验对象,用3种不同强度的超声波对其进行辐射刺激,共设3个试验组和1个对照组。经过60 d的超声波辐射养殖,结果表明:各组间体重存在极显著性差异(P<0.01),其中每天受频率为23 kHz、声源声强为200 mW/cm2的连续超声波辐射刺激5 min的试验组鱼,其体重最高,比对照组鱼体重增长约7.58%;但每天受频率为23 kHz、声源声强为600 mW/cm2的连续超声波辐射刺激5 min的鱼体,其体重反而比对照组体重减少约5.80%。各试验组尼罗罗非鱼体重与胃蛋白酶活性之间没有明显关系。当环境声强为1.58~1.60 mW/cm2时,对尼罗罗非鱼幼鱼生长比较有利。     

双重 PC R检测罗非鱼源无乳链球菌方法的建立

根据罗非鱼源无乳链球菌16S rRNA 基因和sip基因序列,设计、合成2对特异性引物,通过对反应体系和反应条件优化,建立快速检测无乳链球菌的双重PCR方法。该方法扩增无乳链球菌可获得1305 bp和121 bp 2个特异性片段;对6株链球菌属的菌株进行特异性分析,仅无乳链球菌能扩增出16S rRNA 基因和sip基因2条特异性条带,而海豚链球菌无条带检出;经灵敏度试验,可检测到无乳链球菌菌株070717LL的最小量为1.05＆#215;10^2 CFU ;同时,双重PCR可以检测出无乳链球菌菌株070717LL人工感染的罗非鱼脾、脑、肾组织中细菌DNA ,特别是脾脏和肾脏组织的样品检测效果好。结果证明所建立的方法具有快速、特异性强、灵敏度高等优点,适用于对罗非鱼源无乳链球菌病的流行病学调查。     

3个红罗非鱼群体的形态差异分析

通过测定中国台湾红罗非鱼、以色列红罗非鱼和马来西亚红罗非鱼群体的形态参数,采用单因素分析、主成分分析和聚类分析3种多元分析方法,比较了3个红罗非鱼群体的形态差异。通过回归分析,建立多元回归方程,对比分析了3个群体间形态性状对体重的影响。6个可数性状分析结果表明,3个群体在可数性状上无显著差异。在与出肉率有较高相关系数的比例性状上,中国台湾红罗非鱼群体与以色列红罗非鱼、马来西亚红罗非鱼群体均存在显著差异。8个可量比例性状的聚类分析和主成分分析结果均表明,以色列红罗非鱼群体和马来西亚红罗非鱼群体形态最接近,而与中国台湾红罗非鱼群体形态差异较大。主成分分析构建了3个主成分,其贡献率分别为34.804%、16.667%、12.974%,累计贡献率为64.446%。回归分析结果表明,体长、体厚、尾柄高是影响中国台湾红罗非鱼和以色列红罗非鱼群体体重的主要性状,体长、体高、体厚是影响马来西亚红罗非鱼群体体重的主要性状。多元分析结果表明,3个红罗非鱼群体在形态上已经产生一定程度的差异,且主要表现在体高、头长、尾柄高、吻长、全长这5个形态性状指标上。     

遗传标记在罗非鱼良种选育研究中的应用与展望

综述了在近些年中传统遗传标记罗非鱼良种选育相关研究中的应用情况,探讨了多种分子标记联合分析的必要性,展示了罗非鱼选育群体基于SSR/AFLP分别计算的Nei(1978)相似性系数比率稳定分布于0.942 07~0.963 70之间,而群体间SSR/AFLP遗传距离比率全都远大于1,具有良好的区分度。综合多种因素,推荐SSR作为罗非鱼良种选育群体遗传多样性水平的常规监测手段。并指出基于DNA序列测定与生物信息学技术开发的新型分子标记类型应当作为未来罗非鱼良种选育研究的重点方向。     

罗非鱼耐盐数量性状位点(QTL)定位研究

采用190个微卫星分子标记对罗非鱼282个全同胞个体进行数量性状位点(QTL)定位,获得15个罗非鱼耐盐QTL,其中st-c、mst-a可分别解释19.2%的两性耐盐差异和19.1%的雄性耐盐差异,XY性别决定位点、钠钾氯协同转运蛋白2(NKCC2)基因分别定位于st-c、mst-a的峰值处。研究结果表明,罗非鱼海水养殖中采用全雄群体可能具有一定的耐盐优势,NKCC2基因可作为重要的候选基因用于耐盐罗非鱼选育。     

Investigations on the Wound Healing Potential of Tilapia Piscidin (TP)2-5 and TP2-6

Wound healing is a highly orchestrated process involving many cell types, such as keratinocytes, fibroblasts and endothelial cells. This study aimed to evaluate the potential application of synthetic peptides derived from tilapia piscidin (TP)2, TP2-5 and TP2-6 in skin wound healing. The treatment of HaCaT keratinocytes with TP2-5 and TP2-6 did not cause cytotoxicity, but did enhance cell proliferation and migration, which could be attributed to the activation of epidermal growth factor receptor signaling. In CCD-966SK fibroblasts, although TP2-5 (31.25 μg/mL) and TP2-6 (125 μg/mL) showed cytotoxic effects, we observed the significant promotion of cell proliferation and migration at low concentrations. In addition, collagen I, collagen III, and keratinocyte growth factor were upregulated by the peptides. We further found that TP2-5 and TP2-6 showed pro-angiogenic properties, including the enhancement of human umbilical vein endothelial cell (HUVEC) migration and the promotion of neovascularization. In a murine model, wounds treated topically with TP2-5 and TP2-6 were reduced by day 2 post-injury and healed significantly faster than untreated wounds. Taken together, these findings demonstrate that both TP2-5 and TP2-6 have multifaceted effects when used as topical agents for accelerating wound healing.     

Effects of Oxygen Supplementation on Lake Trout Brood Stock

This study was conducted to determine the effects of oxygen supplementation and nitrogen supersaturation on the fecundity and performance of Lewis Lake strain lake trout, Salvelinus namaycush, brood stock. Performance of brood fish held in water supersaturated with oxygen was compared to that of controls raised at or below 100% saturation for 334 days. Incoming water averaged 78.4% saturation in the morning; the addition of oxygen increased saturation to 104.6%. As a result, average morning nitrogen saturation was reduced from 105.7% to 100.9%. In oxygen-supplemented water, peak daily oxygen saturation averged 129.0% in the afternoon. At this saturation level, average nitrogen gas was reduced to 98.4% saturation. Total gas pressure never exceeded 109.1% with oxygen supplementation; however, nitrogen supersaturation reached 110% in raceways with no oxygen supplementation. Weight gain, feed conversion, egg survival, egg size, and number of eggs per female were not affected by increasing oxygen saturation.     

谷氨酸铜对罗非鱼和草鱼生长性能血清生化指标和体组成的影响

为研究谷氨酸铜制剂对罗非鱼、草鱼的生长性能、血清生化指标和鱼体组成的影响，选用180尾罗非鱼、135尾草鱼，分别随机分为3个处理组，每组3个重复，每个重复20或15尾。在基础饲料中添加五水硫酸铜作为对照组（10 mg/kg），试验组添加谷氨酸铜（高、低剂量组分别为10、5 mg/kg，按铜离子计），饲养8周。结果表明：与对照组相比，谷氨酸铜高、低剂量组罗非鱼的增重率分别提高3.9%和5.8%，草鱼的增重率分别提高4.0%和5.9%；罗非鱼特定生长率分别提高1.9%和3.3%，草鱼分别提高2.5%和3.5%；罗非鱼和草鱼的平均饵料系数分别降低7.6%和3.7%。两种鱼的血清生化指标及体组成各试验组间均无显著差别（P＞0.05）。由此可见，日粮中添加适量谷氨酸铜可提高鱼体的生长性能，且效果优于五水硫酸铜。     

The effect of nearly closed RAS on the feed intake and growth of Nile tilapia (Oreochromis niloticus), African catfish (Clarias gariepinus) and European eel (Anguilla anguilla)

One of the challenges that Recirculating Aquaculture Systems (RAS) are still facing is the risk that in RAS fish grow less than in flow-through systems due to the accumulation of substances originating from feed, fish or bacteria associated with the water re-use. The present study investigated whether RAS with high and low accumulation levels of these substances affect feed intake and growth of Nile tilapia Oreochromis niloticus, African catfish Clarias gariepinus, and European eel Anguilla Anguilla. One-hundred and twenty individuals of each species were used (start body weights: Nile tilapia 264.8 ± 8.3 g; African catfish 253.2 ± 2.1 g and European eel 66.6 ± 1.3 g). For a period of 39 days, growth and feed intake were compared between high and low accumulation RAS. HIGH accumulation RAS was designed for maximal accumulation of substances in the water by operating the system at nearly-closed conditions (30 L/kg feed/d), using mature biofilters and high feed loads; and (2) LOW accumulation RAS was designed to be a proxy for flow-through systems by operating at high water exchange rates (1500 L/kg feed/d), new biofilters and low feed load. HIGH accumulation RAS induced a reduction in feed intake (42%) and growth (83%) of Nile tilapia, as compared to systems that are a proxy for flow-through conditions. This effect was not observed in European eel and African catfish. The cause of this reduced feed intake and growth rate of Nile tilapia is still unclear and should be addressed in further studies.     

Economic profitability of Nile tilapia (Oreochromis niloticus L.) production in Kenya

Economic profitability of Nile tilapia production in Kenya was analysed using a model that simulated individual fish growth and took fish population dynamics in the pond into account. The results suggest that the currently practiced mixed‐sex tilapia culture is economically unsustainable. It is suggested that research and extension efforts be geared towards developing monosex Nile tilapia production systems. Nile tilapia culture with African catfish predation should be viewed as an intermediate step towards all‐male Nile tilapia culture. This will allow accumulation of both physical and human capital to support all‐male tilapia culture. Under all‐male culture, economic returns are high enough to justify investment in Nile tilapia culture using borrowed capital. However, the success of monosex culture will depend on the availability and affordability of quality fingerlings and low‐cost fish feeds. The results have a wide application in Sub‐Saharan Africa where mixed‐sex Nile tilapia culture is common.