草鱼生长性状的遗传参数和育种值估计

利用草鱼(Ctenopharyngodon idellus)生长性状选育核心群亲本,采用人工授精方式构建21个全同胞家系,并选用动物模型对16月龄草鱼生长性状进行遗传参数和育种值估计。结果显示,草鱼选育种群的生长性状存在丰富变异。采用约束极大似然法估计方差组分,发现草鱼体重、体长和体高性状的遗传力分别为0.39,0.47,0.21,属于中高遗传力;肥满度性状遗传力为0.11,属于低遗传力;4个性状的共同环境效应值相近且较小,范围为0.07~0.17。采用两性状动物模型分析相关性,发现体重、体长和体高性状间表型和遗传相关系数均达到高度正相关(r=0.88~0.97),而肥满度性状与三者间相关系数接近零,只与体高性状存在一定遗传正相关(r=0.43)。结合各性状遗传变异系数和相对遗传进度,分析表明,以体重为目标性状可便捷有效地改良草鱼生长性能。采用最佳线性无偏估计法预测个体育种值,发现4个性状育种值与表型值的相关系数范围为0.77~0.93。基于单性状育种值和表型值分别进行个体选择,按10%留种率,各性状选留个体相同率为68.75%~81.82%,秩相关系数范围为0.19~0.81,两种选择方式显示出较大差异,且差异大小与性状遗传力成反比例。本研究为草鱼生长性状选择育种提供了理论依据和技术支撑。     

草鱼肠系膜脂肪沉积量的测定与分析

为了精确且批量测定草鱼肠系膜脂肪（肠脂）沉积量，避免传统人工刮取称量方法耗时费力、量化粗糙等问题，本研究利用脂溶性染料油红O可特异性着色脂肪的特性，探索开发出一种便捷定量草鱼肠脂含量的新方法。测试发现，麻醉解剖200尾平均体质量约80 g的草鱼，取出整个内脏团简单处理并塞入PIT个体识别标记后，样品集中进行多聚甲醛固定、无水乙醇脱水、油红O染液定染，可在维持样品组织完整的基础上，实现肠脂组织的特异性、均一化批量染色处理。各染色样品再分别通过无水乙醇溶剂完全萃取，萃取液吸光度测定，并依据绘制的标准曲线（y = 0.0276x + 0.0403, R2 = 0.9997），即可精确获得个体肠脂沉积的相对含量，是以萃取出的油红O质量来表示。对比发现，样品肠脂组织染色-萃取量化结果与传统刮取称量数据保持了较高的相关性（n = 20，r = 0.80）。进一步的统计分析显示，对于同塘养殖体质量变异系数8.93%的草鱼群体（n = 200），萃取测定的肠脂沉积量变异系数达到24.49%，预示该性状具有丰富变异特征及遗传改良潜力。相关与聚类分析显示，肠脂沉积量与内脏质量相关性最高（r = 0.60），并且聚为一类，符合二者同属脏器关联指标的预期。多元线性回归分析显示，利用简单易测的形态指标只能解释肠脂沉积量的少量变异（R2 = 0.20），表明基于表型性状的拟合回归方程进行间接预测的效果不佳，直接测定是该性状精准量化的有效途径。本研究为草鱼体脂性状改良提供了一种性状精确测定方法。     

草鱼幼鱼生长性状和肌肉成分的遗传参数估计

为了研究草鱼幼鱼阶段生长性状和肌肉成分的遗传改良潜力。随机采集288尾人工繁育的4月龄草鱼幼鱼,基于12对微卫星标记,鉴定出来自16个家系（8个母本,9个父本）的273尾个体,各家系、母本和父本对应子代贡献率存在极显著差异（P<0.01）。对草鱼3个生长性状（体质量、体长和肥满度）和2个肌肉成分指标（粗蛋白含量和粗脂肪含量）比较发现,3个生长性状和粗蛋白含量在家系和母系半同胞间存在显著差异（P<0.05）,而3个生长性状和2个肌肉成分指标在父系半同胞间差异均不显著（P>0.05）。基于动物模型和限制性最大似然法,草鱼4月龄体质量、体长、肥满度、粗蛋白含量和粗脂肪含量的遗传力估值分别为0.34、0.33、0.17、0.17和0.20,其中3个生长性状遗传力估值统计检验显著（P<0.05）。遗传相关分析显示,体质量与体长之间呈极显著的高度正相关（0.82, P<0.01）,肥满度与体质量和2个肌肉成分之间存在显著的正相关（0.17-0.29, P<0.05）。研究表明,草鱼4月龄生长性状具有较高的选育潜力,并可通过体长选择实现对体质量的遗传改良;推测在草鱼生长改良过程中,可能会伴随肥满度和粗脂肪含量的变化,这应当引起重视。     

鳜回交子代与亲本子代间体型和体斑特征比较

体型和体斑是鳜鱼育种的重要性状。该研究利用多重比较、杂种指数、主成分分析、判别分析对鳜回交子代[斑鳜(Siniperca scherzeri)♀×杂交鳜(斑鳜♀×鳜S. chuatsi♂)♂]与其亲本(斑鳜、杂交鳜)进行了可量形态性状差异分析,并对回交子代体斑进行了观察。结果显示,回交子代平均杂种指数为38.73,多重比较和杂种指数表明,回交子代体型偏向斑鳜。主成分分析和判别分析表明,回交子代与斑鳜、杂交鳜间的差异性状主要表现在头部隆角、体高/体长、头高/头长、C (隅骨后端至腹鳍起点长)/体长。回交子代、斑鳜与杂交鳜在前3个主成分的三维空间分布上不重叠,相互区分;判别分析可在二维空间上对3个群体进行区分。回交子代体斑主要包括背部鞍状斑与体侧斑纹,可分为4种组合类型,其中45.5%个体具有与斑鳜类似的背部鞍状斑,72.8%个体具有空心斑。研究结果可为鳜鱼回交育种研究与子代鉴定提供基础资料。     

草鱼7个插入/缺失型突变多态性及与幼鱼生长性状关联分析

对草鱼生长性状进行数量性状基因座(quantitative trait locus,QTL)定位过程中,在15号连锁群中定位到一个与体质量相关的QTL,本研究根据已有的草鱼遗传连锁图谱和基因组序列,拟用短片段重复序列(short tandem repeat,STR)分型技术对该连锁群的3个scaffolds中插入/缺失型突变位点进行筛选,以降低分型成本,同时将筛选出的7个多态性位点与草鱼幼鱼生长性状进行关联分析。结果显示,(1)草鱼3个scaffolds中44个插入/缺失型突变位点中有17个简单重复序列(又称微卫星,simple sequence repeats,SSRs),2个位点引物设计不成功,设计的25对引物中仅22对扩增和分型成功;(2) 22个位点中仅有7对引物在4个亲本中存在多态性,直接测序结果发现,STR分型技术不仅可准确对插入/缺失型突变位点进行分型,同时可降低分型成本;(3)将7个插入/缺失型突变位点与323尾选育F2草鱼的生长性状进行关联分析发现,除了位点ID-10H和ID-41F以外,其余5个位点都与草鱼幼鱼的一个或多个生长性状显著相关,其中ID-6H与幼鱼肥满度性状显著相关,位点ID-11F、ID-15F、ID-32F和ID-39F分别与草鱼幼鱼体质量、体长、体宽和体高性状显著相关,可将以上5个与草鱼幼鱼生长性状相关的突变位点用于草鱼生长性状QTL加密和分子标记辅助育种。     

草鱼PRL基因多态性与幼鱼生长性状和肌肉成分的关联分析

为了探索草鱼(Ctenopharyngodon idella)PRL(prolactin)基因多态性与草鱼生长性状和肌肉成分的关联性,通过测序法从10尾草鱼的PRL基因中筛选到6个突变率高于30%的变异位点,包括5个单核苷酸变异位点和1个插入型突变(–/CACTCACTA),分别命名为2551GA、2639GC、3247AG、5197TG、5897GA和3391–+。利用AS-PCR(allele-specific PCR)和基因分型技术对192尾4月龄草鱼的PRL基因变异位点进行检测;基于一般线性模型对变异位点多态性与草鱼生长性状和肌肉成分进行相关性分析。研究发现,2639GC、3391–+和5197TG对体长和体重具有显著影响(P0.05),2639GC对肌肉粗蛋白含量具有显著影响(P0.05)。单个位点基因型比较发现,3391–+的突变型(–+和++)个体的体长和体重均显著高于野生型(––)个体(P0.05);2639GC的GC及5197TG的突变型(TG和GG)个体的体长和体重分别显著低于2639GC的GG和5197TG的TT野生型(P0.05);2639GC突变型(CC)个体的粗蛋白含量显著高于2639GC其他基因型(GG和GC)个体(P0.05)。两位点组合比较发现,含3391–+突变型(–+和++)的组合对应体长和体重普遍高于其他组,含2639GC的CC突变型的组合对应粗脂肪含量和粗蛋白含量普遍较高,其中粗蛋白含量显著高于其他组(P0.05)。研究表明,草鱼PRL基因多态性与草鱼生长性状和肌肉成分间存在显著关联,推测相关变异位点可作为草鱼生长和肉质改良的候选辅助标记。     

草鱼生长相关的微卫星标记在选育群体中的验证

生长性状是水产动物遗传育种中的重要经济性状,利用与性状相关的分子标记与育种相结合的手段,可以大大加速育种进程。在对草鱼生长性状的前期研究中,采用数量性状位点(QTL)定位的方法,在1号连锁群中发现了2个与生长相关的QTL。在此基础上,实验利用这2个QTL侧翼的2对微卫星标记(CID391_2、CID1512、CID973_1和CID254_1),对长江草鱼选育群体的480个个体进行分析,以期基于草鱼QTL定位结果,对草鱼生长相关的微卫星标记在选育群体中进行验证。结果显示:(1)4个微卫星标记在该群体中均具有高度多态性,其中各位点观测等位基因数(N_a)为12～23个,有效等位基因数(N_e)为4～12个,观测杂合度(H_o)为0.607～0.904,期望杂合度(H_e)为0.751～0.902;(2)利用方差分析及多重比较对4个多态性的微卫星标记与选育草鱼群体的生长性状(体质量和体长)进行关联分析,发现CID391_2在雌性个体中,各基因型与体质量和体长之间均无显著差异;而在雄性个体中,各基因型与体质量和体长之间差异显著。CID1512、CID973_1和CID254_1在雌性或雄性个体中,各基因型与体质量和体长之间均具有显著差异。研究表明,对草鱼生长相关的微卫星标记在选育群体中的验证结果,为进一步开展草鱼生长性状QTL定位研究和基于QTL结果的分子标记辅助育种(MAS)实践奠定理论基础。     

坛紫菜种质品系表型性状的变异规律分析

坛紫菜(Pyropia haitanensis)的表型性状是遗传育种的主要考察指标。研究以福建省坛紫菜种质资源库保存的73份种质品系为实验材料,对藻体的5个形态特征和14个数量性状数据进行了统计分析,以探讨坛紫菜表型性状的遗传变异规律。结果表明,坛紫菜藻体的形状、颜色、锯齿大小和扭曲程度4个形态特征与藻体长度、宽度、重量和厚度4个数量性状极显著相关(P0.01),叶片基部形状与藻体长度、宽度、鲜重和厚度显著相关(P0.05);比较不同性状均值发现,线形藻体的平均长度增长速度最快,基部为心脏形的藻体平均重量增长速度最快,无锯齿的藻体厚度最薄。巢式方差分析结果显示,坛紫菜品系间的遗传变异(72.79%)远大于品系内(21.46%),说明品系间的变异是坛紫菜表型变异的主要来源。坛紫菜藻体各表型性状的变异系数为7.14%~35.99%,其中藻体厚度变异系数最低,而单株藻体重量的变异系数最高,说明藻体厚度的选择潜力相对较小,而重量的选择潜力则较大。这些数据为后续坛紫菜的遗传育种提供了基本资料。     

草鱼GH基因3''部分序列多态性与生长性状及肌肉成分的相关性分析

为了解草鱼GH基因多态性与早期生长性状及肌肉成分的相关性,实验利用直接测序法从156尾草鱼GH基因的3′部分序列中共筛选到9个变异位点(分别命名为SNP1~SNP9:G2825A、G2914T、T2966G、A3002T、T3022C、A3301G、C3463T、C3547T、C3620T)。卡方检验结果显示,9个位点均未显著偏离Hardy-Weinberg平衡,且均表现为中等多态性(0.25PIC0.5);经连锁不平衡分析发现,SNP3、SNP4和SNP5位点为一组完美连锁不平衡,SNP2、SNP7、SNP9位点为一组完美连锁不平衡;GH基因3′部分序列5个位点单倍型分析共发现6种单倍型,其中Hap1(30.4%)所占的比例最高,Hap6(4.8%)所占比例最低。利用GLM及多重比较对草鱼GH基因中9个SNPs多态性与早期生长性状和肌肉成分进行相关性分析,发现SNP2和SNP3位点的纯合突变型在体质量、体长和粗脂肪性状上均显著高于野生型和杂合突变型;在双倍型分析时得出了相似的结果,同时含有SNP2和SNP3位点纯合突变的双倍型组合在生长和粗脂肪性状上均显著性高于其他组合。研究表明,草鱼GH基因中SNP2和SNP3位点与早期生长性状及肌肉成分存在显著性相关,可作为草鱼生长及肉质改良的候选辅助分子标记,并且为进一步对相关变异位点的功能验证奠定研究基础。     

金草鱼肌肉品质和营养成分分析及评价

为了评价金草鱼(Ctenopharyngodon idellus)肌肉品质和营养成分,对同塘养殖的金草鱼和普通草鱼肌肉品质和营养成分进行比较分析及评价。结果显示:金草鱼和草鱼的含肉率分别为70.57%和73.13%,肌肉水分含量分别为78.60%和78.40%,粗蛋白含量分别为19.55%和19.95%,粗灰分含量分别为1.80%和1.45%,粗脂肪含量分别为0.39%和0.50%。金草鱼肌肉的冷冻渗出率和蒸煮失重率低于草鱼,贮存损失为2.64%,显著低于草鱼的4.87%。金草鱼肌肉系水力大于草鱼,保水性更好。金草鱼与草鱼肌肉中氨基酸组成合理,必需氨基酸含量丰富,分别为5.45%和5.35%,必需氨基酸/总氨基酸分别为35.16和35.21,必需氨基酸指数为58.88和56.85;不饱和脂肪酸含量丰富,分别占总脂肪酸的73.44%和70.43%。综合分析表明,金草鱼与草鱼均为高蛋白、低脂肪的食品,具有较高的营养价值。金草鱼肌肉的系水力、必需氨基酸含量和不饱和脂肪酸含量大于草鱼。     

Estimates of Heritabilities and Genetic Correlations for Growth and Gonad Traits in Blunt Snout Bream,Megalobrama amblycephala

Blunt snout bream, Megalobrama amblycephala, is an herbivorous freshwater fish and has been recognized as a main aquaculture species in the Chinese freshwater polyculture system. The objective of the study is to estimate the genetic parameters for growth, body shape, and gonad traits for M. amblycephala at 1 yr of age. The phenotypic analysis showed that coefficients of variation for gonad traits had large variation relative to the other traits analyzed, and there was no sexual dimorphism by comparing growth and body shape in M. amblycephala. Based on restricted maximum likelihood and Markov chain Monte Carlo Bayesian methods using the animal model, the heritabilities of body weight (0.423–0.504), body length (0.309–0.678), body height (0.408–0.599), and dressed weight (0.359–0.643) were moderate and high, while the other traits, including conditional factor (0.029–0.199), body shape coefficient (0.095–0.405), edible ratio (0.073–0.207), gonad weight (0.018–0.170), and gonadosomatic index (0.050–0.222), had moderate or low heritabilities. High genetic and phenotypic correlations were found among growth traits, but not between growth traits and body shape or gonad traits except dressed weight. Based on our results, it could be efficient to combine the selection on body weight for fast growth and nonearly sexual maturity varieties of M. amblycephala breeding.     

Effects of dietary choline supplementation on growth performance,lipid deposition and intestinal enzyme activities of blunt snout bream Megalobrama amblycephal fed high‐lipid diet

This study aimed to investigate the effects of dietary choline supplementation on growth, lipid deposition and intestinal enzyme activities of Megalobrama amblycephala. Fish were fed four diets with two lipid levels (50 and 150 g kg^?1) and two choline supplementations (600 and 1600 mg kg^?1) for 8 weeks. Feed conversion ratio (FCR), viscerosomatic index (VSI), hepatosomatic index (HSI), intraperitoneal fat (IPF) ratio, whole‐body and muscle lipid contents, intestinal lipase activities and lipoprotein lipase (LPL) activities all increased significantly (P < 0.05) as lipid levels increased, whereas the opposite was true for whole‐body and muscle moisture contents and intestinal amylase activities. VSI, IPF ratio and whole‐body lipid contents all decreased significantly (P < 0.05) with increasing dietary choline supplementations. Weight gain, muscle moisture content all increased significantly (P < 0.05) with increasing dietary choline supplementations when dietary lipid levels reached 150 g kg^?1, whereas the opposite was true for FCR, IPF ratio, IPF and liver LPL activities. In addition, abnormal hepatocytes were found in the liver of fish fed 150 g kg^?1 lipid with 600 mg kg^?1 choline supplementation. The result of this study indicated that extra choline supplementation can improve growth performance, intestinal enzymes activities and reduce excessive lipid deposition of M. amblycephala fed high lipid.     

不同乳酸菌对发酵草鱼品质的影响

为探明不同乳酸菌对发酵草鱼微生物数量和理化性质的影响,进一步提高发酵鱼制品的品质,实验对草鱼背部肌肉经不同乳酸菌(植物乳杆菌、戊糖片球菌和副干酪乳杆菌)发酵后制品的微生物数量、pH、总酸、水分含量、白度、氨基酸态氮、硫代巴比妥酸和挥发性盐基氮等进行分析,探究不同乳酸菌在草鱼发酵过程中(0～15d)对其品质的影响.结果显...     

Protein‐sparing capability of dietary lipid in herbivorous and omnivorous freshwater finfish: a comparative case study on grass carp (Ctenopharyngodon idella) and tilapia (Oreochromis niloticus × O. aureus)

Two, 8‐week feeding trials were conducted to compare protein‐sparing capability of dietary lipid in herbivorous grass carp (Ctenopharyngodon idella) and omnivorous tilapia (Oreochomis niloticus × O. aureus). Utilizing a 2 × 3 factorial design, experimental diets containing two levels of crude protein (380 and 250 g kg⁻¹) and three levels of lipid (0, 40 and 100 g kg⁻¹) were formulated for use in both feeding trials. Growth performances showed better response of both fish fed 380 g kg⁻¹ protein diet than those fed 250 g kg⁻¹ protein diet. Despite the dietary protein level, weight gain (WG), specific growth ratio (SGR), feed conversion ratio (FCR) and protein efficiency ratio were much higher (P < 0.05) for grass carp fed 40 g kg⁻¹ lipid diet than those fed 100 g kg⁻¹ lipid diet; however, there were no significant differences in tilapia fed the two diets. The feed intake of grass carp fed lipid‐free diet was the lowest, but it tended to decrease with increase in dietary lipids in tilapia. Lipid retention (LR) was negatively correlated with dietary lipid concentration of both fish. Viscerosomatic index (VSI), hepatosomatic index (HSI), intraperitoneal fat ratio (IPF) and whole‐body and liver lipid content positively correlated with dietary lipid concentration of both fish. Plasma parameters and liver enzymes activities were also positively correlated with dietary lipid concentration of both fish. Liver lipid contents were higher and enzymes activities were lower in grass carp when compared with tilapia. These data suggested that there was no evidence of a protein‐sparing effect of dietary lipids in grass carp. Tilapia has relatively higher capacity to endure high dietary lipid level compared to grass carp.     

不同碳水化合物和蛋白质水平膨化饲料对大规格草鱼生长、肠道消化酶及血清指标的影响

为探究不同碳水化合物和蛋白质水平膨化饲料对大规格草鱼生长、体成分、肠道消化酶和血清指标的影响,以初始体质量(398.6±5.9)g的大规格草鱼为研究对象,设置不同碳水化合物/蛋白质水平分别为C31P30、C34P28、C37P26、C40P24、C43P22、C46P20、C49P18的7组膨化饲料,养殖周期为16周。实验结果显示,各饲料组草鱼成活率(SR)差异不显著,随着蛋白质水平的下降、碳水化合物水平的升高,增重率(WGR)呈下降趋势,蛋白质效率(PER)呈升高趋势;肝体比(HSI)、脏体比(VSI)、肠体比(ISI)、肌肉和肝脏粗脂肪(CF)含量均有随饲料碳水化合物水平升高而升高的趋势。随着饲料中碳水化合物水平升高、蛋白质水平下降,各组间草鱼肌肉粗蛋白质(CP)含量无显著差异;肝糖原、肌糖原含量呈升高趋势,饲料中碳水化合物水平分别高于46%和40%时,肝糖原、肌糖原含量显著升高。肠道胰蛋白酶(PRS)和淀粉酶(AMS)活性随饲料中碳水化合物水平的升高呈先下降后升高趋势,脂肪酶(LPS)活性呈升高趋势;血清总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白(LDL)、高密度脂蛋白(HDL)含量及谷草转氨酶与丙转氨酶(GOT/GPT)比值都随饲料中碳水化合物水平升高和蛋白质水平下降而呈升高的趋势。本实验结果显示:当饲料碳水化合物水平高于37%、蛋白质水平低于26%时,将显著影响草鱼的生长,饲料中高碳水化合物水平将导致鱼体肝体比、脏体比、肠体比以及肌肉和肝脏脂肪含量升高。     

Preliminary results on quality and quality changes in reared meagre (Argyrosomus regius): body and fillet traits and freshness changes in refrigerated commercial-size fish

Meagre (Argyrosomus regius) intensively reared in tank by a Tuscany farm and fed commercial diets, were examined to study a) marketable and flesh nutritional traits in commercial-size fish and b) loss of freshness under refrigerated storage condition. Eighty fish, sampled in May, July and November (at 24, 26, 30 months of age) were submitted to linear measurements and weight of the most important body components. Whole fillets were analysed for moisture, lipid and fatty acid composition. Data were analysed by ANOVA (sampling date). A sub sample of fifty-four meagre (902–1840 g b.w.) was stored at 1 °C with ice cover and evaluated every 24 h after death until spoilage for the EU freshness classes, dielectric properties, rigor index, muscular and eye liquor pH, K₁% freshness index. Data were analysed by regression on time after death. A small sample of meagre (n = 6) and sea bass (Dicentrarchus labrax) (n = 6), reared in analogous rearing condition in the same farm were compared by ANCOVA on body weight (average b.w. 668 g). Meagre were characterised by 1.04 condition factor, 44% fillets, 6% viscera, negligible mesenteric fat (1%) and 94.5% dressing yield. The head incidence increased (P < 0.01) with b.w. increase. Moisture increased while lipid decreased (P < 0.01) in fillet from July to November (74.47 vs 75.96%; 2.93 vs 2.06%). An index of thrombogenicity calculated from the quantitative fatty acid composition was very low (0.10). In comparison with sea bass of the same body weight, meagre had greater length (41.2 vs 37.6 cm), head incidence (29.9 vs 20.7%) and dressing (94.8 vs 89.2%) and lower viscera (5.2 vs 10.9%), mesenteric fat (0.9 vs 7.9%) and intramuscular fat (2.24 vs 12.78%) incidences. Meagre had a 9-day shelf-life (E class from 1^st to 3^rdd and A class from 4^th to 7^thd). Rigor index and impedance remained higher than 90% and 66, respectively until the 3^rdd after death. The quality traits found for this species indicated meagre as a promising candidate for Mediterranean aquaculture.     

Effect of Protein and Starch Level in Practical Extruded Diets on Growth,Feed Utilization,Body Composition,and Hepatic Transaminases of Juvenile Grass Carp,Ctenopharyngodon idella

Six practical extruded diets were formulated to investigate the effect of graded levels of starch (17, 22, and 26%) associated with either 30 or 34% protein level on growth, feed utilization, body composition, and hepatic transaminases of juvenile grass carp, Ctenopharyngodon idella. Over an 8‐wk growth trial, survival rates (99–100%) were not significantly affected (P > 0.05) by dietary treatments. Independent of dietary starch level, weight gain (WG, %), specific growth rate (SGR, %/d), and feed efficiency ratio (FER) showed significant better response (P < 0.05) of fish fed 34% protein diet than those of fish fed 30% protein diet. Protein productive value (PPV) was only affected by dietary protein level, with higher values in the 34% protein level than their 30% counterparts. Irrespective of dietary protein level, lipid productive value (LPV), energy productive value (EPV), viscerosomatic index (VSI, %), intraperitoneal fat ratio (IPF, %), and whole body, liver, and muscle lipid level increased with increasing starch supply. At the same protein level, plasma triacylglycerol (TG), cholesterol (CHO), and low density lipoprotein‐cholesterol (LDL‐C) increased when dietary starch level increased from 17 to 26%. Neither dietary protein level nor starch level affected activities of hepatic alanine aminotransferase (ALAT) and aspartate transferase (ASAT). The overall results in this study suggested that the higher 34% protein was superior for juvenile grass carp and an increase in dietary starch level did not improve growth or protein utilization but enhanced whole‐body lipid deposition and liver, viscera and muscle lipid level. The diet containing 34% protein and 17% starch was optimal for practical production of juvenile grass carp.     

Phenotypic and genetic parameters of body composition traits and flesh colour in Atlantic salmon, Salmo salar L.

Data obtained on 3.5-year-old offspring of 58 sires and 171 dams (two year classes) of Atlantic salmon, Salmo salar L., were analysed. A substantial effect of sexual maturation status was demonstrated for several body composition traits, most pronounced for the content of fat and dry matter of muscle. Maturation effects generally exceeded estimated sex effects. Intermediate estimates of heritability (0.20-0.30) derived from the sire component of variance were obtained for intestinal fat weight, intestinal fat index, dressing percentage and fat and dry matter content of muscle. Corresponding parameters of the subjectively scored traits belly flap constitution, amount of intestinal fat and flesh colour were all low (= 0.10). Heritabilities derived from the sire and dam components of variance were generally similar in magnitude, indicating the absence of non-additive genetic and environmental effects common to full-sibs. Viewed in the context of likely selection goals for commercial breeding schemes, the results did not reveal major adverse genetic relationships among the investigated traits. However, the estimated genetic correlations of muscle fat with body weight (0.42 ± 0.17) and intestinal fat index (-0.64 ± 0.19) may be unfavourable.     

亚洲草鱼群体的差异甲基化分析

为探究水产养殖过程中DNA甲基化对亚洲草鱼群体人工驯化与环境选择适应的影响,本实验对亚洲范围内8个地区的养殖和野生草鱼群体进行了全基因组甲基化测序,测序序列经质控后比对到草鱼参考基因组上,并进行差异甲基化分析和功能富集分析。结果显示,甲基化测序共获得308.15 Gbp测序数据,平均测序深度31×,平均比对率62.97%。对5个养殖群体分别与野生背景群体间进行差异甲基化分析,共发掘出76 422个差异甲基化位点、3 737个差异甲基化区域、1 950个差异甲基化基因。功能分析发现,差异甲基化基因被注释到血管生成、神经嵴细胞迁移、T细胞分化、颅骨系统发育、肌肉细胞发育等GO功能分类中。KEGG代谢途径富集分析的结果显示,差异甲基化基因主要参与细胞黏附连接、Notch信号通路和Wnt信号通路等代谢途径。在这些功能注释的基因中,有许多与神经、免疫、骨骼和肌肉等组织发育相关的重要基因,如sema3d、sema5bb和nrg2a等。本研究进一步对表观遗传修饰在草鱼人工驯化和环境选择适应作用机制的探究奠定了基础,为保存和科学利用草鱼种质资源提供了有价值的遗传基础数据。