凡纳滨对虾选育群体子代免疫性能的初步分析

在凡纳滨对虾群体选择育种研究中,利用1个经过人工选择和自交传代的凡纳滨对虾群体F2A,连续两个世代对该群体自交繁育的子代及其与其它群体杂交繁育的子代,进行免疫指标的检测和分析。结果表明,该群体两个世代的自交组繁育的子代F3A和F4A组,多项免疫指标都高于同世代的其它交配组,其中血细胞吞噬杀伤活性F3A组比同世代其它组高14.8%和64.3%,F4A组比同世代的其他组高27.0%～44.8%;血清溶细胞活性F3A组比同世代其它组高76.3%和74.6%,F4A组比同世代其它组高36.5%～58.3%;血清蛋白含量也高于其它组;只有酚氧化酶低于其它组。显示在人工选育条件下,凡纳滨对虾群体内自交传代,可能有利于群体免疫性能的遗传。但杂交组在生长和抗逆方面表现的杂交优势,与其偏低的免疫指标不一致。     

凡纳滨对虾全同胞家系的建立及生长比较

全同胞家系是遗传分析的重要材料。采用自然交配法建立了62个凡纳滨对虾第一代全同胞家系,对其中17个家系进行了比较研究。结果表明,各家系的孵化率、出苗率与雌性亲本的大小相关性不显著。17个家系中有7个家系显示生长优势,其大小顺序依次是A02＞A11＞A01＞A17＞A06＞A08＞A16;7个家系在40周内的生长速度较17个家系的平均值高23.2%。在所有家系中,A01、A02、A11等3个家系的体重显著大于其它家系（P＜0.05）,其平均生长速度较所有家系平均生长速度分别快25.5%、31.6%和31.0%。这3个家系的整齐度良好,在养殖中期的个体变异系数分别为11.58%、9.95%和8.48%,后期均小于5%,显示出优良的经济性状,为进一步选择培育凡纳滨对虾的快速生长新品系奠定了基础。     

凡纳滨对虾野生群体F1与近交群体杂交和自交子代的抗逆、生长性状比较

为了探究野生群体的引入对凡纳滨对虾(Litopenaeus vannamei)近交群体子代性状的影响,利用源自厄瓜多尔海区的野生群体群选F_1(EC)与自建的全同胞兄妹近交群体(ZG)双列杂交,构建了EC♂×EC♀(EE)、ZG♂×ZG♀(GG)、EC♂×ZG♀(EG)、ZG♂×EC♀(GE) 4个子代群体,并对4个群体的仔虾进行了急性低盐度、亚硝酸盐暴露下的存活率和急性微囊藻毒素(MC-LR)暴露下的抗氧化酶活性分析,同时进行了养殖生长性状测试。结果显示:4个群体仔虾急性低盐度暴露下的存活率、急性MC-LR暴露下的抗逆性和生长性状都表现为EEGEEGGG,急性亚硝酸盐暴露下的存活率GEEEEGGG;杂交群体GE在急性低盐度、亚硝酸盐暴露和生长性状的杂种优势率分别为31.83%、77.01%和2.77%;而EG群体的杂种优势率分别为-19.21%、-8.01%和-8.14%,性状弱于双亲中值。4个群体的抗逆、生长性状总体表现为EEGEEGGG。研究发现:凡纳滨对虾杂交群体的性状以母本遗传占主导优势,近交群体的性状衰退可能是导致以其为母本的杂交子代性状退化的主因;凡纳滨对虾选育工作可能需要每年补充外源基础群体,才能保持选育群体的优势性状。     

饲料中添加凹土对凡纳滨对虾存活和生长的影响

研究了饲料中添加凹土(0.0%、0.5%、1.0%、2.0%、4.0%和8.0%)对凡纳滨对虾(1.04～1.06 g)存活和生长的影响.实验在淮海工学院江苏省海洋生物技术重点建设实验室进行,凡纳滨对虾(Litopenaeus vannamei)幼虾购白海南某育苗场;实验采用单因子6水平设计,每个水族箱放养10尾对虾,每个水平设3个重复.实验前停食24 h,称其初始体重.日投饵2次,过量投饵;投饵2.5 h后从每个水族箱收集残饵、粪便和虾壳.实验周期30 d.所得数据用单因素方差分析和Turkey's多重比较进行处理.结果表明,饲料中添加凹土显著地影响对虾的特定生长率,而对存活率、摄食量、饲料系数和吸收效率的影响不显著;在2.0%凹土水平,凡纳滨对虾的特定生长率显著高于0.0%凹土水平,但与其它处理差异不显著;总的看来,2.0%凹土添加组对虾的饲料系数低于其它处理,而摄食量高于其它处理.     

饲料中添加凹土对凡纳滨对虾存活和生长的影响

研究了饲料中添加凹土（０．０％、０．５％、１．０％、２．０％、４．０％和８．０％）对凡纳滨对虾（１．０４～１．０６ｇ）存活和生长的影响。实验在淮海工学院江苏省海洋生物技术重点建设实验室进行,凡纳滨对虾（Ｌｉｔｏｐｅｎａｅｕｓｖａｎｎａｍｅｉ）幼虾购自海南某育苗场;实验采用单因子６水平设计,每个水族箱放养１０尾对虾,每个水平设３个重复。实验前停食２４ｈ,称其初始体重。日投饵２次,过量投饵;投饵２．５ｈ后从每个水族箱收集残饵、粪便和虾壳。实验周期３０ｄ。所得数据用单因素方差分析和Ｔｕｒｋｅｙ′ｓ多重比较进行处理。结果表明,饲料中添加凹土显著地影响对虾的特定生长率,而对存活率、摄食量、饲料系数和吸收效率的影响不显著;在２．０％凹土水平,凡纳滨对虾的特定生长率显著高于０．０％凹土水平,但与其它处理差异不显著;总的看来,２．０％凹土添加组对虾的饲料系数低于其它处理,而摄食量高于其它处理。     

密度和投饵频率对凡纳滨对虾存活和生长的影响

研究了密度(361、722和1 084尾/m2)和投饵频率(1、2和4次/d)对凡纳滨对虾存活和生长的影响,实验时间6周。结果表明:在3个密度水平,随投饵频率的升高,对虾摄食量、存活率、特定生长率、饲料系数和吸收效率均呈上升趋势;在3个投饵频率水平,随密度的升高,对虾摄食量、存活率、特定生长率和饲料系数均呈下降趋势,而吸收效率呈上升趋势。     

凡纳滨对虾群体自交与杂交子代幼体对低温、低盐抗逆性与生长比较

为提高凡纳滨对虾种苗质量,探索群体选择育种和杂交育种方法在凡纳滨对虾大规模人工育苗生产中的应用,对1个经过人工选择的凡纳滨对虾群体A的自交和杂交子代的抗逆性和生长性状进行了比较。群体A是2008年来自美国种虾的子一代,并经过2个世代的人工选择和自交传代。群体B为2010年来自广东的繁育群体。A群体自交,及其与B群体的正、反杂交,产生3组不同交配组合的子代。对3个组合后代仔虾幼体的抗低温、低盐能力及养成期的生长性状进行比较分析,结果表明,以A群体为母本的杂交组AB抗逆性最强,以B群体为母本的杂交组BA抗逆性次之,而A群体自交组抗逆性最弱。在低温(13.0±0.9) ℃和低盐4.7条件下,AB组存活率分别比AA组高27.6%和64.4%。3个组合养成期的体质量生长速度为AB组(253±55) mg/d、 BA组(208±52) mg/d、AA组(219±36) mg/d,AB组比BA组快21.6%,比AA组快15.5%。研究表明,凡纳滨对虾的杂交优势与亲本的提纯、选优密切相关。     

盐度对凡纳滨对虾存活、生长和能量收支的影响

研究了盐度(0·5、5、10、15、20、25、30和35)对凡纳滨对虾Litopenaeus vannamei(平均初始湿重0·776~0.781g)存活、生长和能量收支的影响。实验周期45d。结果表明,(1)对虾特定生长率、摄食量、饲料转换效率和吸收效率均以20盐度最高,而存活率以35盐度最高;(2)在0.5盐度下,对虾特定生长率、摄食量和吸收效率均最低。     

凡纳滨对虾7个引进群体的生长性能评估

为了对凡纳滨对虾7个引进群体的生长性能进行评估,通过巢式交配和人工授精的方式,用201 1年源自不同国家和地区的7个凡纳滨对虾群体建立了130个全同胞家系,包括17个杂交组合(正反交合并)和7个自交组合.各家系的仔虾、幼虾经中间暂养和标记后混合,在河北黄骅(HBHH)和青岛鳌山(QDAS)两个养殖场养殖,测定了153日龄虾体质量性状.用混合线性模型估计不同群体和家系体质量最小二乘均值,计算不同杂交组合杂种优势率,评估不同群体和杂交组合的生长性能.结果表明,凡纳滨对虾各群体体质量变异系数变化范围为13％～26％;UA5、UA4和SIN三个群体为亲本的153日龄虾体质量最小二乘均值均较高,分别比群体均值高5.34％、2.51％和1.67％,是体质量性状育种的优良亲本;杂交组合均值(18.14 g)比自交组合(17.17 g)高5.65％,杂交组合UA4×UA5体质量最小二乘均值最高(19.52 g),比杂交组合均值高7.61％;组合杂种优势率在-1.77％～ 11.72％,均值为5.45％,大部分杂交组合(＞75％)存在正向杂种优势,UA1×UA2杂交组合杂种优势率最高.研究结果有助于提高凡纳滨对虾生长性能遗传选择的准确性,并为实现良种选育奠定基础.     

凡纳滨对虾引进群体和养殖群体的PCR-RFLP分析

采用PCR-RFLP方法,对2008年引进的SPF凡纳滨对虾群体(G0)与2006年引进亲虾繁育的两代群体(G1、G2)的遗传结构进行了分析。使用AluI、TaqI、M boI、SpeI、SspI共5种限制性内切酶对线粒体DNA控制区进行单酶切分析,酶切得到的单倍型在2~4个之间,三个群体的复合单倍型类型分别有3个、7个和9个,没有为三个群体所共有的复合单倍型,复合单倍型的分布显示群体间差异显著。三个群体(G0、G1、G2)的核苷酸多样度π值逐渐增加,分别为0.033 3、0.128 6、0.134 9,复合单倍型多样度h分别为0.622 2、0.850 0、0.847 0,说明养殖群体的遗传多样性大于引进群体。聚类分析的结果表明随着养殖世代的增加,养殖群体与引进群体的差异呈增大的趋势。由此推测G0与G1的亲本存在较大的遗传差异,并且在使用引进群体作为亲本的育种过程中可能出现了种质混杂。     

Comparison of different types and levels of commercial soybean lecithin supplemented in semipurified diets for juvenile Litopenaeus vannamei Boone

Two 6-week growth trials were conducted to determine the dietary phospholipids (PL) requirement of Litopenaeus vannamei juveniles and to compare the effect of different types of soybean lecithin on shrimp growth and survival. In the first trial, a basal diet and diets containing 1.5, 3 or 5% (dry-weight basis) of Type I lecithin (97.6% PL) and 1.5 or 3% of Type II lecithin (71.4% PL) were evaluated. In the second trial, the basal diet and diets containing 1, 2 or 4% of either Type I or Type II lecithin and 1 or 2% of Type III lecithin (48.4% PL) were evaluated. Results showed that there was no interaction between lecithin type and PL level on shrimp growth or survival. Shrimp growth increased with PL levels up to 3–5% of diet. No significant differences were observed for instantaneous growth rate (IGR) of shrimp fed the different types of lecithin at the same inclusion level, and no effect of PL level and lecithin type on shrimp survival was found. Thus, the recommended level of PL supplementation in diets for L. vannamei juveniles ranges from 3 to 5% of diet.     

Effect of dietary phosphorus sources and varying levels of supplemental phosphorus on survival,growth and body composition of postlarval shrimp (Litopenaeus vannamei)

Two experiments were conducted for 30 days each to investigate the effective phosphorus source and supplemental phosphorus levels for postlarval Litopenaeus vannamei. The first experiment was performed in postlarval shrimp (mean initial wet weight 2 mg) fed four isoenergic and isonitrogenous diets containing three supplemented inorganic phosphorus sources [D1: no supplemental phosphorus, D2: NaH₂PO₄·2H₂O, D3: KH₂PO₄·2H₂O, D4: Ca(H₂PO₄)₂·2H₂O]. The quantities of the three supplemental NaH₂PO₄·2H₂O, KH₂PO₄·2H₂O and Ca(H₂PO₄)₂·2H₂O were 11.6, 12.8 and 10 g kg^?1 of the diet, respectively in order to make the three diets have the same total phosphorus. Growth performance (final mean body weight, FBW; weight gain, WG; specific growth ratio, SGR) of shrimp in D3 treatment was the highest and had significant difference with the D1 treatment. The survival of shrimp in D3 treatment was the highest and had significant difference with the other treatments. The mineral concentration and body composition of shrimp were not significantly different among treatments. We could conclude that KH₂PO₄·2H₂O was the optimal phosphorus source for postlarval L. vannamei from the growth performance and survival. The second experiment was performed in postlarval shrimp (mean initial wet weight 0.88 mg) fed four isoenergic and isonitrogenous diets containing four supplemental KH₂PO₄·2H₂O levels (d1, d2, d3 and d4 with 0, 5, 10 and 20 g kg^?1, respectively). Shrimp in d2 treatment showed the highest growth performance and survival and also showed significant difference with other diet treatments. The whole body content of zinc (Zn) increased with the increase of dietary KH₂PO₄·2H₂O and significant differences were observed when dietary KH₂PO₄·2H₂O reached 5 g kg^?1, excess KH₂PO₄·2H₂O supplementation (10 and 20 g kg^?1) had a negative effect on Zn content, the Zn content significantly decreased when KH₂PO₄·2H₂O was 20 g kg^?1. We can conclude that the amount of total phosphorus in the diet should be maintained between 20.9 and 22.0 g kg^?1, the amount of supplemental KH₂PO₄·2H₂O in the diet is less than 10 g kg^?1.     

凡纳滨对虾(Litopenaeus vannamei)抗WSSV选育家系的建立及其抗病特性

2002-2007年在人工感染白斑综合症病毒(white spot syndrome virus, WSSV)的基础上进行一代个体选育（G1）后,对凡纳滨对虾连续进行了4代家系选育,共建立120个抗WSSV家系,感染实验结果表明：G2~G5选育家系对虾平均成活率分别为5.57%±9.83%, 8.66%±11.52%, 9.52%±8.84% 和 13.79%±12.86%;G2~ G5选育家系对虾平均成活率的变异系数分别为1.77、1.40、0.97和0.87。根据每个家系对虾的成活情况可分为敏感、中等抗性和高抗性家系,G2至G5敏感家系在各代选育家系中的比例逐年下降,分别占76.5%、55.2%、51.4%和33.3%,抗病成活率分别为0.44%±1.09%、0.78%±1.70%、2.27%±2.76%和2.44%±3.09%,感染WSSV后2~3 d出现1个急性死亡高峰;中等抗病家系在各代选育家系中的比例逐年上升,分别占0、20.7%、31.1%和38.5%,抗病成活率分别为0、9.08%±1.46%、10.7%±1.41%和11.36%±3.30%,感染WSSV后出现2个死亡高峰,第1死亡高峰值大于第2高峰;高抗家系在各代选育家系中的比例逐年上升（G4除外）,分别占23.5%、24.1%、17.1%和28.2%,抗病成活率分别为22.23%±5.21%、22.7%±12.30%、24.45%±6.56%和28.98%±8.09%,感染WSSV后出现2个死亡高峰,第1死亡高峰至小于第2高峰。经连续的定向选育,选育对虾抗病性状一代比一代强,表现出明显的抗病性能,特别是高抗对虾不仅死亡率低且其死亡高峰推迟2～3d,延缓了对虾WSSV暴发的时间,但是每代每尾对虾平均产卵量逐年下降（P<0.05）。     

凡纳滨对虾引进群体和2个养殖群体遗传变异的微卫星分析

利用8个微卫星标记对引进的SPF凡纳滨对虾G0和两个养殖群体(G1,G2)进行遗传多样性分析。8个座位共获得64个等位基因,位点的等位基因数在5~l3之间。多态信息含量PIC在0.405 2~0.869 3之间,其中有6个位点为高度多态位点,适合于多态性分析。8个座位丢失的和新产生的等位基因共30个,占总数的47%。3个群体的平均观测杂合度分别为0.193 8、0.196 1、0.232 5,说明3个群体的遗传多样性较低。对近交系数Fis分析显示3个群体中存在近交,通过对哈迪温伯格平衡检验,显示所有座位均显著偏离平衡,存在杂合子缺失。通过配对Fst和Ne i遗传距离分析,显示3个群体之间有明显的遗传分化,说明种群结构发生了明显的遗传变异,变异可能来自于突变、随机漂变和选择的共同作用。实验结果能够很好地解释经过若干群体选育后,子代群体发生种质退化的现状,由此建议综合采用遗传育种的方法从引进的亲虾中筛选出性状优良稳定的仔虾作为虾苗。     

Effects of dietary chitosan on growth,survival and stress tolerance of postlarval shrimp,Litopenaeus vannamei

The effect of chitosan, a polymer of glucosamine obtained by the deacetylation of chitin, on growth, survival and stress tolerance was studied in postlarval Litopenaeus vannamei. An experiment was performed with postlarval shrimp (mean initial wet weight 1.2 mg) fed five isoenergic and isonitrogenous diets containing five supplemented levels of chitosan (0, 0.5, 1, 2 and 4 g kg^?1 diet, respectively). The five compound diets (C0, C0.5, C1, C2 and C4) sustained shrimp growth throughout the experiment. Growth performance (final body weights; weight gain; SGR: specific growth rate) in shrimp fed diet C2 was significantly higher than that in shrimp fed diets C0, C0.5 and C1 (P < 0.05), diet C4 treatment provided intermediate growth result. The survival in shrimp fed diet C1 was significantly higher than that in shrimp fed C0 diet (P < 0.05), other diets treatments gave the intermediate survival results. No significant differences were found in growth and survival between diet C2 and C4 treatments. After 9 days of a stress tolerance test, survival in shrimp fed diets C1, C2 and C4 was significantly higher than that in shrimp fed diets C0 and C0.5. We concluded from this experiment that the incorporation of a moderate dietary chitosan was beneficial to the development of postlarval L. vannamei. Considering the effect of chitosan on both growth and survival of postlarval L. vannamei, second‐degree polynomial regression of SGR and survival indicated optimum supplement of dietary chitosan at 2.67 and 2.13 g kg^?1, respectively, so the level of chitosan supplemented in the diet should be between 2.13 and 2.67 g kg^?1.