Effect of parental origin on early life history traits of European eel

Establishment of European eel (Anguilla anguilla) hatchery production will rely on selectively bred individuals that produce progeny with the best traits in successive generations. As such, this study used a quantitative genetic breeding design, between four females and nine males (four wild‐caught and five cultured), to investigate the effect of paternal origin (wild‐caught vs. cultured) and quantify the relative importance of parental effects, including genetic compatibility, on early life history (ELH) performance traits (i.e. fertilization success, embryonic survival at 32 hr post‐fertilization, hatch success and larval deformities at 2 days post‐hatch) of European eel. Wild‐caught males had higher (56%) spermatocrit values than cultured males (45%), while fertilization success, embryonic survival, hatch success and larval deformities were not significantly impacted by paternal origin. This demonstrates that short‐term domestication of male eels does not negatively affect offspring quality and enables the consideration of cultured male broodstock in future breeding programmes. Moreover, paternity significantly explained 9.5% of the variability in embryonic survival, providing further evidence that paternal effects need to be taken into consideration in assisted reproduction protocols. Furthermore, maternity significantly explained 54.8% of the variation for fertilization success, 61.7% for embryonic survival, 88.1% for hatching success and 62.8% for larval deformities, validating that maternity is a major factor influencing these “critical” ELH traits. At last, the parental interaction explained 12.8% of the variation for fertilization success, 8.3% for embryonic survival, 4.5% for hatch success and 20.5% for larval deformities. Thus, we conclude that eggs of one female can develop more successfully when crossed with a compatible male, highlighting the importance of mate choice for successful propagation of high‐quality offspring. Together, this knowledge will improve early offspring performance, leading to future breeding programmes for this critically endangered and economically important species.     

Sperm production and quality in European eel (Anguilla anguilla) in relation to hormonal treatment

Aquaculture production relies on controlled management of gametogenesis, especially in species where assisted reproduction is needed for obtaining gametes in captivity. The present study used human chorionic gonadotropin (hCG) treatments to induce and sustain spermatogenesis in European eel (Anguilla anguilla). The aim was to evaluate effects of strip-spawning timing (12 vs. 24 hr) after weekly administration of hCG and the necessity of a primer dose (in addition to weekly hormonal treatment) prior to strip spawning (primer vs. no-primer) on sperm quality parameters. Sperm parameters included milt production (weight), density and sperm kinematics at Week 9, 11 and 13 after onset of treatment. Spermiation commenced in 11.5% of males in Week 5 and by Week 9, and all males produced milt. Male weight, milt production, sperm density and spermatocrit did not differ among hormonal treatments during the experimental period. Overall, male weight decreased from 106.3 to 93.0 g, milt weight increased from 3.5 to 5.4 g, sperm density counts decreased from 11.7 × 10⁹ to 10.5 × 10⁹ cells/ml, and spermatocrit decreased from 46.5% to 40.5%. Furthermore, spermatocrit was positively related to haemocytometer counts (R² = .86, p < .001), providing a reliable indicator of sperm density. Differences in sperm kinematics were observed depending on strip-spawning timing after hormonal injection (12 vs. 24 hr) but with no consistent pattern. These sperm quality parameters also did not consistently differ between the no-primer and primer treatments. Considering that each male may be stripped 4–5 times over the 2–3 months spawning season, omitting the primer would reduce animal handling, material costs and labour intensity, while sustaining high-quality sperm production.     

欧洲鳗鲡三类苗养殖技术初探

本试验应用膨化饲料养殖欧洲鳗鲡（Anguilla anguilla）三类苗。经过110d的养殖,两个试验组的平均体重分别达到16．13g和15．39g,相对增重率分别为151．1％和142．4％。日均增重量分别为88．3mg和82．2mg。平行养殖试验结果显示存活率分别为97．7％和98．5％,饲料转化率分别为59．1％和58．4％。整个养殖过程基本不换水,完全不用任何药物。     

外源性卵黄蛋白对鳗鲡GTH细胞和卵母细胞超微结构的影响

外源性卵黄蛋白与鲤鱼垂体（CPG）加绒毛膜促性腺激素（HCG）混合注射（试验组）对鳗鲡具有明显的催热作用，卵巢成热系数平均为56．17±11．74％，是对照组（CPG加HCG组）的2．87倍。试验组脑垂体促性腺激素细胞（GTH细胞）中除含有数量较多的小分泌颗粒外，球状分泌颗粒增加，内质网池扩大；卵母细胞直径为450．0微米，双层滤泡膜和放射带充分发育。对照组GTH细胞的球状分泌颗粒直径和内质网扩大均小于试验组；卵母细胞直径为270．0微米。而饲养在海水中75天，未经注射催情药物的雌鳗，脑垂体GTH细胞仅有小分泌颗粒，未见球状分泌颗粒，卵母细胞的放射带正在形成，胞内开始出现脂肪油球。试验结果表明，外源性卵黄蛋白与CPG加HCG混合注射有明显协同作用，对卵母细胞成热有显著促进作用。     

人工感染嗜水气单胞菌对日本鳗鲡非特异性免疫功能的影响

对注射嗜水气单胞菌菌液(3×106CFU·mL-1)的鳗鲡,进行外周血的血相、白细胞吞噬活性、血清抗菌活力等免疫学指标的测定.结果显示:在感染的初期,感染组外周血中白细胞和淋巴细胞数量、白细胞吞噬活性及血清抗菌活力较对照组均有显著提高,其中感染组的外周血的白细胞、淋巴细胞的数量与对照组相比均有显著提高,感染组粒细胞数量...     

长江近口段鳗苗捕捞量的时间格局及其与生态因子的GAM模型分析

为研究长江口鳗苗捕捞量与生态因子的相互关系,于2012年汛期对长江靖江段鳗苗的捕捞量进行了监测,采用广义可加模型(GAM)对日捕捞量与水温、潮差、气压、浑浊度等生态因子之间的相关性作了分析。结果显示,靖江段鳗苗汛期为1月下旬—4月上旬,单船总捕捞量为221~443尾,平均(344.8±83.4)尾。1月均值仅0.4尾/d,且空网率高达90.9%;4月为旺汛期,均值10.4尾/d,空网率仅为10.0%。GAM模型显示,潮汐周期—月份交互项、水温和潮差对鳗苗日捕捞量的影响显著,而气压、浊度和月相周期对鳗苗日捕捞量的影响不显著。潮汐周期—月份交互项、水温和潮差对鳗苗日捕捞量的偏差解释率分别为42.4%、19.1%和13.1%,均呈现正相关关系。统计也显示,日捕捞量表现出上、下弦月较低、新月或满月前后较高的半月周期波动。鳗苗捕获的最低水温为6.3℃,而10~15℃为适宜捕捞水温。高潮期和低潮期分别占总捕捞量的76.8%和23.2%。研究表明,长江口鳗苗在借助潮汐流而快速溯河的过程中,部分在口门水域即被捕获,部分滞留在了长江河口段,而影响鳗苗溯河的重要生态因子是潮汐和水温。     

日本鳗鲡胶原蛋白和小清蛋白的过敏原性

以日本鳗鲡皮与肌肉组织为研究对象,采用碱溶、酸溶、盐析、冻干等方法纯化得到胶原蛋白,采用加热、饱和硫酸铵分级盐析、DEAE-Sepharose阴离子交换层析等方法纯化得到两种亚型的小清蛋白(PV-Ⅰ和PV-Ⅱ),纯化的目标蛋白经动物特异性抗体的免疫印迹实验确证。酶联免疫吸附测定和免疫印迹分析结果显示,纯化的胶原蛋白和小清蛋白分别与鱼类过敏患者阳性血清发生特异性反应,且二者之间无免疫交叉反应。体外模拟胃液消化实验和SDS-PAGE分析结果显示,胶原蛋白和小清蛋白均具有较高的消化稳定性。结果提示,日本鳗胶原蛋白和小清蛋白具有较高的消化稳定性和免疫原性,二者可引发不同患者的IgE介导特异性超敏反应。     

间接ELISA法研究嗜水气单胞菌对鳗鲡表皮黏液的黏附特性

采用间接ELISA法研究菌浓度、孵育时间、温度、pH、阳离子及碳源等因子对嗜水气单胞菌(Aeromonas hydrophila)黏附鳗鲡(Anguilla anguilla)表皮黏液的影响。结果表明, 改良后的间接ELISA法的检测灵敏度约为9.92×10⁴ CFU, 细菌的黏附量随菌浓度的升高而逐渐增大并符合饱和黏附动力学方程: y=0.135ln(x)-0.936(R²= 0.986); 嗜水气单胞菌黏附鳗鲡表皮黏液的最佳条件为: 温度20~28℃, pH 6.2~6.6, NaCl、MgCl₂质量浓度分别为15~25 g/L和3 g/L, 孵育时间为150 min。碳源对嗜水气单胞菌的黏附作用有不同程度的影响, 葡萄糖和麦芽糖能显著提高嗜水气单胞菌的黏附量(P<0. 05), 果糖则显著降低嗜水气单胞菌的黏附量(P<0. 05)。以上结果说明, 嗜水气单胞菌对鳗鲡表皮黏液具有较强的黏附作用, 且其黏附作用具有可控性。

     

澳洲长鳍鳗染色体组型的初步研究

以澳洲长鳍鳗(Anguilla reinhardtii)头肾组织为材料,采用腹腔注射植物血细胞凝集素(PHA)、秋水仙素和空气干燥法制备染色体标本,进行染色体组型分析.结果显示:澳洲长鳍鳗染色体为38条,核型公式为2n=14m+6sm+18t,NF=58;未发现随体、次级缢痕及异形染色体.