Cao Baoxiang

凡纳滨对虾( Litopenaeus vannamei )选育群体与杂交群体遗传多样性差异及其在低温条件下生长性能的比较

选取连续3年选育的凡纳滨对虾(Litopenaeus vannamei)群体作为选育群体(SP)，选育群体与引进的凡纳滨对虾群体的杂交F1代群体(HP)，探究了这2个群体在低温条件下的生长性能及遗传多样性的差异。结果显示，在生长性能方面，HP群体与SP群体的平均体重分别为(13.18±3.65) g和(12.20±3.14) g，变异系数(CV)分别为27.69%和25.74%。HP群体的体重和其他可测量性状的平均值均大于SP群体。单因素方差分析(One-way ANOVA)表明，2个群体体重(BW)和第3腹节宽(TASW)存在极显著差异(P < 0.01)。HP群体的特定增长率(SGR)和绝对增重率(AGR)分别为(5.09±0.61) %/d和(0.26±0.60) g/d，SP群体的SGR和AGR分别为(4.94±0.57) %/d和(0.24±0.63) g/d，HP群体的SGR和AGR均极显著高于SP群体(P < 0.01)，表明HP群体相对于SP群体有着明显的生长优势。在遗传多样性方面，HP群体的平均等位基因数(Na=7.9) 略高于SP群体(Na=7.6)。HP群体和SP群体的平均多态信息含量(PIC)分别为0.63和0.62，均为高度多态。2个群体的平均观测杂合度(Ho)分别为0.492(HP群体)和0.483(SP群体)，平均期望杂合度(He)分别为0.675(HP群体)和0.663(SP群体)，HP群体的He和Ho均略高于SP群体，表明HP群体相比SP群体有着更加丰富的遗传多样性。遗传分化分析表明，2个群体间遗传分化指数(Fst)为0.1556，表明群体间遗传分化水平显著。

中国对虾（Fenneropenaeus chinensis）和凡纳滨对虾（Litopenaeus vannamei）对白斑综合征病毒的敏感性比较

本研究分别对中国对虾野生群体(Wild-Fenneropenaeus chinensis, W-Fc)、中国对虾选育群体‘黄海2号’(Selected-Fenneropenaeus chinensis, S-Fc)和凡纳滨对虾商业一代苗种(Commercial-Litopenaeus vannamei, C-Lv)采用单尾定量口饲感染白斑综合征病毒(WSSV)，比较W-Fc、S-Fc及C-Lv对WSSV的敏感性差异。结果显示，感染同等含量WSSV后，W-Fc、S-Fc和C-Lv的平均存活时间分别为(124.11±39.49) h、(166.79±51.54) h和(136.90±41.99) h，3组对虾间的平均存活时间存在显著性差异(P < 0.05)。3组对虾在感染期间的死亡趋势：W-Fc在96 h达到死亡高峰，并且一直持续到216 h；S-Fc和C-Lv在144 h出现死亡高峰。另外，分别在感染后的3、6、12、24、36、48、72、144 h共8个时间点对3组对虾进行活体取样，利用实时荧光定量RT-PCR技术对其进行了病毒载量检测，从对虾存活时间和体内肌肉组织病毒载量的角度比较不同对虾抗病性能的差异，结果如下：48 h时，W-Fc、S-Fc和C-Lv3对虾体内肌肉组织的病毒载量分别为(1.22×106±6.14×105)、(7.10×103±7.26×102)和(1.50×104± 4.19×103) copies/ng DNA；144 h时，3组对虾体内肌肉组织病毒载量分别为(8.44×106±1.25×106)、(3.21×106±8.21×105)和(1.49×106±6.59×105) copies/ng DNA。实验结果显示，3组对虾对WSSV敏感性从高到低依次为中国对虾野生群体、凡纳滨对虾商业苗种、中国对虾选育群体，表明中国对虾选育群体‘黄海2号’在人工感染WSSV条件下表现出了良好的抗病性能。

聚β-羟基丁酸酯对中国明对虾( Fenneropenaeus chinensis )非特异性免疫相关酶的影响

本研究以中国明对虾(Fenneropenaeus chinensis)为对象，探讨不同浓度的聚β-羟基丁酸酯(Poly-β-hydroxybutyrate，PHB)对其非特异性免疫相关酶的影响。实验采用单因子浓度梯度法，对健康的中国明对虾投喂添加不同浓度PHB (0、0.5%、1.0%、2.5%、5.0%、10.0%)的饲料，分别对应对照组C和实验组E0.5、E1.0、E2.5、E5.0、E10.0组，饲喂6周，统计每组中国明对虾的死亡率和相对免疫保护率，检测总抗氧化能力(T-AOC)、酸性磷酸酶(ACP)、过氧化物酶(POD)和过氧化氢酶(CAT)、超氧化物歧化酶(SOD) 5种酶的活力及丙二醛(MDA)含量与时间、PHB浓度的变化关系。结果显示，实验组的相对免疫保护率随PHB浓度的增加呈现先上升后下降的趋势。E1.0组为最高值，并且与其他各组相比差异显著(P < 0.05)。随PHB浓度的增加，免疫酶活力整体变化趋势为先上升后下降。在时间分布上，饲喂2–3周时，酶活力呈现高水平表达，其中，T-AOC在血清(E1.0、E2.5组)、肝胰腺(E1.0组)；ACP在血清(E1.0、E2.5组)、肝胰腺(E1.0组)；CAT在血清(E0.5、E1.0、E2.5组)、肝胰腺(E0.5、E1.0、E10.0组)；POD在血清和肝胰腺(E0.5、E1.0、E2.5组)；SOD在血清和肝胰腺(E1.0组)以及MDA在血清(E1.0组)、肝胰腺(E0.5，E1.0组)较其他组均具有显著性差异(P < 0.05)。研究表明，PHB添加剂对中国明对虾免疫水平的提高具有促进作用。综合各组和各时间段免疫酶的变化，E1.0为最适浓度组，投喂2–3周时其免疫酶总体具有高水平活力值。

Effects on survival time of Fenneropenaeus chinensis challenged by different doses of WSSV and diets

White spot syndrome virus(WSSV)is one kind of destructive virus affecting shrimp industry in the world.Output of Fenneropenaeus chinensis which once was a staple species has been greatly affected by outbreak of WSSV since 1993 in China.To produce WSSV-resistance shrimp strains is an important approach to revive the shrimp industry.To select survived F.chinensis as broodstock via WSSV challenge test can increase the efficiency of breeding.However,mortality of shrimps could reach nearly 100% once they were infected with WSSV,which increases the difficulty for shrimp breeding.In this study for the purpose to reveal effect of different WSSV amount on F.chinensis,juvenile F.chinensis were infected with a certain amount of WSSV individually and the survival time and survival rate were observed.The results showed that survival time of shrimps infected with 5.2×108 copies,1.0×109 copies and 2.1×109 copies of WSSV respectively was 389.3,323.3 and 187.3 h and significant different(P0.01).The cumulative mortalities of all the shrimps finally reached 100%.The survival time increased while shrimps were fed with less WSSV bait.For the purpose to reveal the effect of diets on the ability for disease resistance,shrimps infected with WSSV were fed with different diets of live brine shrimps,commercial bait and fresh clam.It was showed that the survival time of infected shrimps fed with live brine shrimps,fresh clam and commercial bait respectively was 281.7,173.9 and 164.9 h.The survival time of infected shrimp fed with live brine shrimps was significantly higher than that fed by commercial bait and fresh clam respectively(P0.01).There was no significant difference of survival time between infected shrimps fed with commercial bait and fresh clam(P0.05).Cumulative mortalities of all the groups of infected shrimps that fed with different diets were 100%.Live brine shrimp is better than commercial bait and fresh clam for the purpose of enhancing shrimp WSSV resistance ability.