太平洋牡蛎与近江牡蛎的种间杂交

为了评估太平洋牡蛎与近江牡蛎能否产生远缘杂种优势,于2010年5月,以成熟的两种牡蛎亲本为材料开展了2×2远缘杂交研究,由长牡蛎自繁组GG(Crassostrea gigas♀×C.gigas♂)、近江牡蛎自繁组AA(C.ariakensis♀×C.ariakensis♂)、正交组GA(Crassostreagigas♀×C.ariakensis♂)、反交组AG(C.ariakensis♀×C.gigas♂)4个实验组组成。分析了子代早期表型性状和杂种优势,并对杂交子代进行了遗传鉴定。结果表明:GA杂交组与AG组的受精强度具有不对称性。幼虫浮游期间,表型性状的中亲杂种优势几乎为0,GA组生长与存活性状表现出积极的单亲杂种优势,而AG组则具有明显的远交衰退现象;幼虫早期表型性状受到母本效应影响,而后减弱。变态期间,GA组变态率较高,得到了大量杂交稚贝;而AG组变态率极低,仅获得了72个杂交稚贝。稚贝培育期间,稚贝表现出中亲生长劣势与存活优势;GA组具有明显的单亲生长与存活优势,而AG组则表现出生长劣势并具有一定程度的存活优势。利用复合COI及ITS2鉴定了种间杂交子结果表明:正反交组杂交子均为真正意义上的两性融合杂交子。实验获得了具有显著杂种优势的GA组杂交子,为现有牡蛎的遗传改良提供了新的方向。     

太平牡蛎与大连湾牡蛎杂交实验

本文报道了１９９３年４月５日－５月２５日，对太平洋牡蛎和大连湾牡蛎进行人工杂交的试验，两种牡蛎种间的杂交是可行的，杂交后代具有较高的受精率和成活率，以及较快的生长速度，在一定程度上反映了杂种优势，通过试验结果看出，两种牡蛎有着较近的亲缘关系。     

巨蛎属牡蛎遗传多样性研究

用ＲＰＤ方法获得的几种牡蛎间的遗传距离表明，我国北方海域确定存在大连湾牡蛎，褶牡蛎和近江牡蛎三种自然种。，它们同属巨蛎属。大连湾牡蛎，褶牡蛎和太平洋牡蛎互为姊妹种，近江牡蛎与它们互为非姊妹种。有无长牡蛎以及长牡蛎与上述三种牡蛎的关系有待进一步研究     

太平牡蛎（Crassostrea gigas）与大连湾牡蛎（Ostreatalienwhamensis）杂交实验

本文报道了１９９３年４月５日～５月２５日，对太平洋牡蛎和大连湾牡蛎进行人工杂交的试验。两种牡蛎种间的杂交是可行的。杂交后代具有较高的受精率和成活率，以及较快的生长速度，在一定程度上反映了杂种优势，通过试验结果看出，两种牡蛎有着较近的亲缘关系。     

北方沿海香港牡蛎（♀）×长牡蛎（♂）杂种中期优势评估

为了评估香港牡蛎(♀)×长牡蛎(♂)杂种在北方沿海养殖中期能否产生种间杂种优势,在分析了早期杂种优势的基础上,以9个香港牡蛎自繁家系、9个长牡蛎自繁家系作为对照,以45个种间杂交家系为研究对象,进一步评估了中期杂种存活、生长及产量性状的杂种潜力及其优势。结果发现:1对于存活性状而言(360日龄),香港牡蛎存活率较低仅为9.09%,死亡主要发生在越冬期间(90~180日龄);长牡蛎存活率居中为51.26%,存活力下降主要原因是繁殖后夏季高温致死(360日龄);而种间杂种的存活率相对较高为87.64%,表现出明显的存活优势,其杂种潜力hp=2.72,杂种优势H=189.88。2对于生长性状而言(360日龄),从壳高水平上分析,长牡蛎平均壳高(50.74 mm)最大,显著大于香港牡蛎(45.17 mm)及杂交家系(42.70 mm);且种间杂交家系壳高显著小于两亲本子代;其杂种潜力hp=-1.89,杂种优势H=-10.97。从鲜重上看,长牡蛎的鲜重(17.24 g)最大,显著大于香港牡蛎(12.58 g)及种间杂交家系(9.47 g),且三者间彼此差异显著;其杂种潜力hp=-2.33,杂种优势H=-36.46。3对于产量而言,长牡蛎产量最高为3.22 kg,显著大于香港牡蛎(0.41 kg),与杂交家系无显著差异(2.98 kg);其杂种潜力hp=0.83,杂种优势H=63.97。研究表明,杂种在北方沿海养殖具有很好的抗低温、抗高盐能力,且存活力较强,但是生长性状表现出远交衰退特点。虽然产量性状具有杂种优势,略低于长牡蛎,但由于杂种外观上与香港牡蛎极其相似,故可以考虑将其作为北方牡蛎养殖的新品系(种)。同时,杂种在华南沿海是否具有杂种优势有待于进一步研究。     

太平洋牡蛎与葡萄牙牡蛎两亚种间杂交及其早期阶段生长与存活的杂种优势

利用山东青岛养殖的太平洋牡蛎(N)与汕头本地养殖的葡萄牙牡蛎(S)两个近缘种为亲本,采用正交设计建立了杂种组NS(N♂×S♀)和SN(S♂×N♀)与纯种组NN(N♂×N♀)和SS(S♂×S♀)4个不同的遗传组合,通过比较不同阶段(幼虫期、稚贝期、养成阶段)的生长和存活数据,研究了牡蛎近缘种间的杂种优势,目的为改良牡蛎的生产性状。结果表明,这两个近缘种之间杂交能够产生显著的杂种优势,杂交后代的生长与存活两个表型性状都得到改良。杂交组比近交组生长得快,杂种优势在幼虫期为37.44%,稚贝期为42.47%。杂交组也比近交组存活率高,8日龄幼虫存活率的杂种优势为76.80%、14日龄幼虫存活率的杂种优势可达107.70%,60、90和105日龄稚贝存活率的杂种优势分别为17.30%、15.62%和9.08%。研究表明,通过太平洋牡蛎和葡萄牙牡蛎两个近缘种间的杂交有望解决牡蛎养殖产业存在的育苗难、存活率低、生长慢、个体小等问题。     

香港巨牡蛎与长牡蛎种间杂交及早期杂种优势分析

为测定香港巨牡蛎(Crassostrea hongkongensis♀×C.hongkongensis♂)、长牡蛎自繁家系(C.gigas♀×C.gigas♂)及其两者种间杂交家系(C.hongkongensis♀×C.gigas♂)子代的早期表型性状,评估种间杂种潜力,分析早期种间杂种优势,实验于2010年7月,采用1雄对3雌的巢式设计建立了9个香港巨牡蛎自繁家系(Crassostrea hongkongensis♀×C.hongkongensis♂)(HH11、HH12、HH13……HH33)、9个长牡蛎自繁家系(C.gigas♀×C.gigas♂)(GG11、GG12、GG13……GG33)及45个种间杂交家系(C.hongkongensis♀×C.gigas♂)(HG11、HG12、HG13……HG153)。结果发现,种间杂交家系受精率及孵化率平均水平的杂种潜力hp<-1,表现出显著的杂种劣势;出现了一定程度的种间配子不兼容现象,而且存在着显著的个体间差异。从其总体水平上看,幼虫生长性状的杂种潜力hp<-1,表现出显著的杂种劣势,出现了远交衰退现象;幼虫存活性状的杂种潜力hp在-1～1之间,虽然具有正向优势,但达不到显著标准;幼虫变态率的杂种潜力hp>1,表现出显著的杂种优势。     

香港巨牡蛎与近江牡蛎杂交及回交子代早期生长发育比较

为评估香港巨牡蛎与近江牡蛎杂交及回交育种的可行性,本文以香港巨牡蛎(Crassostrea hongkongensis)与近江牡蛎(Crassostrea ariakensis)为材料,比较了两种牡蛎杂交与回交子代的受精率、孵化率、幼虫及稚贝的生长和存活率。结果表明：香港巨牡蛎卵子可以与近江牡蛎精子受精,受精率为47.33±2.52%,但近江牡蛎卵子与香港巨牡蛎精子不受精。在回交实验中,香港巨牡蛎(H♀)与近江牡蛎(A♂)的杂交牡蛎 (HA)与香港巨牡蛎(HH)或近江牡蛎(AA)都可以正常交配,但各回交组受精率明显低于两牡蛎自交组(P＜0.05)。受精后,HA与AA回交组的孵化率最低,分别为20.33±2.08%(♀A×♂HA),55.67±2.52%(♀HA×♂A),其它各实验组孵化率均大于70%。幼虫期, HA幼虫存活率明显低于两牡蛎自交组HH和AA(P＜0.05);HA幼虫生长快于AA, 但慢于HH;♀A×♂HA回交组和HA自繁组的幼虫存活率为0。稚贝期,HA稚贝存活率与HH、AA自交组存活率差异不显著(P>0.05)。HA稚贝生长快于HH, 但慢于AA。另外,研究发现♀H×♂HA回交组幼虫和稚贝的生长与HA差异不显著(P>0.05),优于其它回交组;♀H×♂HA回交组幼虫的存活率与HA差异不显著(P>0.05),其稚贝的存活率虽低于HA,但优于其它回交组。本研究为牡蛎种间杂交及回交育种奠定了一定的理论基础。     

牡蛎的品质及其开发利用

牡蛎是沿海习见且大量生长的一种贝类，属于软体动物门、瓣鳃纲、牡蛎科。我国沿海盛产的牡蛎，主要有近江牡蛎、长牡蛎、褶牡蛎、花缘牡蛎、大连湾牡蛎、密鳞牡蛎等。牡蛎是广东沿海养殖的主要贝类之一，碍石湾、红海湾、深圳湾、唐家湾、镇海湾和海陵湾等地有大量养殖。     

外海区吊养褶牡蛎探析

近几年,由于养殖工艺的改进,内海褶牡蛎养殖操作更加简便,生产成本也大大降低,发展十分迅速。目前,内海区养殖显然已密度过大,导致牡蛎生长缓慢而且不肥,产量极低甚至绝收。为了改变这种状况,拓宽褶牡蛎养殖范围,我们在浅海10米等深线以外的海区进行吊蛎养殖试验。现将试验情况简介如下:     

四种海胆杂交的可行性及子代的早期发育

报道了中国北部沿海马粪海胆、海刺猬、光棘球海胆三种主要海胆与引自日本的中间球海胆四种海胆之间的不同组合的杂交试验及其子代浮游幼体及幼海胆的早期生长发育.结果表明,采用生殖调控可使不同海胆达到同步繁殖,在8～24℃下各种海胆杂交组合的受精率与亲本亲缘关系有关,同时受到双亲繁殖适宜温度的影响,受精率介于0～69.6%之间,均低于自交组.以马粪海胆和海刺猬为亲本的正反交、以马粪海胆和中间球海胆为亲本的正反交以及马粪海胆()×光棘球海胆()各组杂交胚胎均可发育至四腕幼虫,但畸形率较高,浮游时间比自交组延长3～10d,在其中的3个杂交组得到了幼海胆,经过14个月的室内培育,杂交组成活率低于自交组,壳直径达2.59～2.88cin.     

Fatty acids as a tool to compare cachara (Pseudoplatystoma reticulatum) (Siluriformes: Pimelodidae) and hybrid (Pseudoplatystoma corruscans?×?Pseudoplatystoma reticulatum) larvae during early development

In this study, we investigated the physiological alterations during ontogeny for cachara (Pseudoplatystoma reticulatum) and their hybrid larvae (Pseudoplatystoma corruscans?×?P. reticulatum) using lipids and fatty acids as physiological tools to elucidate the basis for differences in these groups?? productivity in an industrial setting. Eggs and larvae samples were collected during January and February of 2008 in the city of Bandeirantes, MS, and were divided into three primary phases: phase I (0?C16?h after fertilization); phase II (24?h after fertilization to 6?days after fertilization); and phase III (7?C25?days after fertilization). The larvae of both groups showed a high degree of similarity, suggesting that the hybrid larvae showed a high level of heritability from the cachara broodstock. Analysis of the total lipid content provided evidence that there is no alteration in lipid concentration during ontogeny for both groups (i.e., the cachara and hybrids). However, the fatty acid profile showed that during the endogenous feeding period (phase II), when the larvae must use the energy reserves from the mother, the cachara larvae used mainly monounsaturated fatty acids for development. This is typical for most fish species, though notably, the hybrids preferentially used saturated fatty acids. Furthermore, certain specific changes demonstrate unique patterns of energy utilization and structural substrates, which may aid in elucidating the empirical differences reported by fish farmers (i.e., that the hybrids perform better than cacharas in captivity).     

虹鳟不同养殖群体杂交F_1及其自繁系生产性能的比较

利用5个不同遗传背景的虹鳟养殖群体(以A、B、C、D、E分别表示虹鳟的渤海、丹麦、道氏、挪威、加州养殖群体)为材料,采用单因子和多因子两种交配策略,于2004年12月14日,建立了虹鳟不同亲本的杂交系和自繁系,由20个正、反交组合与5个自繁群组成,对其生产性能进行了近两年的比较试验。结果表明:从开食到1+龄鱼阶段(2005-03~2006-10),各杂交组合成活率的平均值与渤海、丹麦、道氏、挪威和加州自繁系相比分别提高了25.21%、2.34%、7.18%、4.18%和5.92%;各杂交组合饲料系数的平均值比渤海自繁系降低了19.74%,与其他养殖群体相比差异不显著(P>0.05);A♀×B♂、C♀×A♂和C♀×B♂组合的生长速度相对于五个自繁系分别提高了13.1%、9.2%和1.5%,且差异显著(P<0.05)。而从11月龄到22月龄(同环境饲育阶段),A♀×B♂、C♀×A♂、C♀×B♂和D♀×B♂组合相对于五个自繁系的平均生长速度分别提高了9.3%、17.5%、16.7%和8.9%,差异极显著(P<0.01)。五个群体间存在的遗传差异是它们能够获得杂种优势和性状得到改良的基础。     

熊本牡蛎中国群体与美国群体杂交效应及杂交三倍体优势分析

为了评估熊本牡蛎(Crassostreasikamea)中国群体与美国群体的杂交效应与杂交三倍体优势,构建了杂交群体和自交群体,并使用细胞松弛素B诱导了杂交三倍体,比较分析了幼虫、稚贝与成贝的生长与存活优势。自交群体和杂交群体的幼虫、稚贝与成贝的培养条件均相同,室内培育幼虫,培育密度为4～5个/mL,自然海区养殖稚贝与成贝,养殖密度为40～45个/吊。结果表明,与自交组相比,杂交二倍体具有较高的卵裂率(13.61%)与D幼率(5.67%)(P0.05),但杂交二倍体幼虫的壳高生长表现杂种劣势(–0.43%),而稚贝、成贝的壳长与壳高的生长表现杂种优势,平均优势率分别为3.96%与6.65%。杂交三倍体诱导组幼虫的壳高生长优势率为3.69%,稚贝及成贝的壳长与壳高平均生长优势率分别为12.69%与13.64%,并且日龄越大生长优势越显著。总体上,杂交三倍体诱导组在3～180日龄具有存活劣势,并且15日龄存活劣势率最大(–48.72%),而在360日龄存活优势率为6.70%。杂交二倍体幼虫与成贝均具有存活优势,平均优势率分别为10.44%与4.59%。本研究表明熊本牡蛎中美地理群体杂交二倍体的生长和存活优于自交二倍体,而杂交三倍体诱导组的生长优势较显著,并且在成贝期具有显著的成活率优势,表明杂交三倍体诱导组的优势来源于三倍体优势和部分杂种优势。     

延迟投饵对奥尼罗非鱼仔鱼摄食、生长和存活的影响

在盐度为5‰,水温(28±0.5)℃的条件下,对延迟投饵0~7d的奥尼罗非鱼(Oreochromis niloticus×O.aureus)仔鱼摄食、生长与存活进行了研究,并确定了仔鱼的饥饿不可逆点(PNR)。试验于仔鱼开口的当天开始试验。结果显示:仔鱼于3日龄开口;延迟投饵0~7 d组,投饵2 h后仔鱼摄食发生率分别为20%、100%、83.3%、36.7%、13.3%、6.7%、3.3%和0%,各组之间差异显著(P<0.05);延迟投饵在2 d以内,10日龄仔鱼体长和体重与对照组无显著差异(P>0.05),延迟投饵超过2 d,体长和体重显著低于对照组(P<0.05);奥尼罗非鱼仔鱼存活率随延迟投饵天数增加而降低,延迟0~2 d的10日龄仔鱼的存活率相差不大,介于78.6%~79.3%,各组差异不显著(P>0.05),延迟投饵超过2 d的仔鱼存活率较低,介于0%~33.3%;奥尼罗非鱼仔鱼的不可逆点出现在仔鱼开口后第4 d,开始投喂的最佳时间在仔鱼开口后的3 d之内。     

中华草龟(♀)与中华花龟(♂)及其杂种F_1代染色体及同工酶比较

采用肾细胞体内注射法分析了中华草龟(Chinemys reevesii)(♀)、中华花龟(Ocadia sinensis)(♂)及其杂种F1代的染色体核型。三种龟染色体倍数为2 n=52,核型公式为18 m+10 st+24 t,臂数NF=80。采用聚丙烯酰胺垂直板电泳法检测了上述三种龟的肌肉、心脏、肝脏、脾脏和肾脏等5种组织的乳酸脱氢酶(LDH)、酯酶(EST)、过氧化物酶(POD)和醇脱氢酶(ADH),分析了三种龟的亲缘关系和遗传多样性。共检测50个基因座位,其中中华草龟15个,中华花龟16个,杂种龟19个,多态位点3个(Ldh-3,Pod-2和Pod-3),多态座位百分比P分别为13.3%、12.5%和15.8%,平均观测杂合度(H0)分别为0.025 6、0.041 7和0.102 3,平均预期杂合度(He)分别为0.041 6、0.040 7和0.074 6,遗传偏离指数(D)分别为-0.386 4、0.023 7和0.372 5。结果表明:杂种F1代群体遗传多样性较高,而亲本群体相对较低;在POD上,杂种F1代与母本中华草龟相近。对比发现,肝脏的POD和LDH及心脏的POD同工酶电泳图谱可以作为鉴别杂种F1代的生化遗传标记。     

Intergeneric Hybridization between Kutum, Rutilus frisii kutum, and Bream, Abramis brama orientalis, of the Caspian Sea

Artificial hybridization was performed between Rutilus frisii kutum and Abramis brama orientalis of the Caspian Sea. Synchronization of spawning of female broodstock of both species was induced by injection of carp pituitary extract. Reciprocal crossings between R. frisii kutum ♀×A. brama orientalis ♂ (RA) and A. brama orientalis ♀×R. frisii kutum ♂ (AR) produced viable hybrid larvae without any clear particular pre‐ or postzygotic isolation phenomena. RA and AR hybrid larvae were reared to fingerling stage with survival rates of 22.5 and 28% and average weight of 6.8 ± 0.17 g and 9.0 ± 0.79 g, respectively. A heterosis of 45% was calculated for weight at fingerling stage. RA and AR hybrid fingerlings were cultured in polyculture along with Chinese carps for 6–7 mo and reached an average weight of 190–195 g and 235–255 g, respectively. Karyotyping of these hybrids revealed a modal diploid number of 2n = 50 for both groups, which is similar to those of the parental species. Discriminant function analysis on 28 morphometric and meristic characteristics of two parental species as well as their hybrids could separate these groups at highly significant level (P < 0.001). These results indicated an overall intermediate inheritance of the studied characters.     

Reproductive ability of triploid ornamental (koi) carp (Cyprinus carpio L.) × goldfish (Carassius auratus L.) hybrids and characteristics of their offspring

The purpose of this study was to investigate reproductive ability of backcross triploid koi (Cyprinus carpio L.) × goldfish (Carassius auratus L.) hybrids. These triploids have been obtained by crossing of F₁ hybrid females producing diploid eggs with males of parental species. Triploid hybrid females, when crossed with goldfish or koi males, produced mostly aneuploid fish with ploidy range from approximately 2.2n–3.2n with a mean value 2.5n; some fish in crosses of triploid females with koi males were tetraploid (4.0n). Since analysed fish had in their genomes one haploid set from parental males, the data indicate that triploid hybrid females mostly produced aneuploid eggs with ploidy range from approximately 1.2n–2.2n and a mean ploidy around 1.5n while some eggs were triploid. Triploid hybrid males were completely sterile and have not released any sperm after hormonal injection. Despite their low viability, some aneuploid fish obtained from triploid hybrid females were raised in indoor recirculating systems until the age of 2 years and their reproductive ability has been evaluated. One aneuploid female with ploidy 2.1n produced larvae with ploidy range from 2.9n to 3.4n with a mean ploidy of 3.1n when crossed with a koi male; about 60% of obtained larvae had ploidy from 3.0n to 3.2n. These data indicate that this female produced mostly eggs with unreduced ploidy level.     

Nutrient composition and sensory evaluation of fillets from wild-type Nile tilapia (Oreochromis niloticus, Linnaeus) and a red hybrid (Florida red tilapia × red O. niloticus)

A comparison of composition and sensory evaluation were performed on fillets of Oreochromis niloticus (wild type) and red hybrid tilapia (RHT) (Florida red tilapia ♂× red O. niloticus♀). Fifty male tilapia, 25 O. niloticus (initial weight 159.3 g) and 25 red hybrid (initial weight 132.4 g), were placed in each of three 2.0 m³ volume tanks. The fish were fed a commercial feed containing 35.9% crude protein during the 120‐day experimental period and then killed in cold water (3°C). All the fish were filleted. Twelve fillets from each treatment were used for proximate analyses, five fillets from each treatment were used for fatty acids analyses and the remaining fillets were used for sensory evaluation. The compositional analyses showed similar moisture, true protein and ash content in both genetic groups, but a lower crude fat content was measured in the red hybrid fillets (0.70%) compared with that of O. niloticus fillets (0.97%). No differences between O. niloticus and the red hybrid were observed in their fillet profile of fatty acids. In the sensory evaluation test, a difference in fillet flavour between both genetic groups was perceived. Of the 112 consumers in the preference test, 81.2% perceived a difference in fillet flavour between the two tilapias, with a general preference for the red hybrid over the wild‐type O. niloticus. The benefits of cultivating a RHT with a low lipid content are discussed.     

Comparison of growth, fillet yield and proximate composition between Stirling Nile tilapia (wild type) (Oreochromis niloticus, Linnaeus) and red hybrid tilapia (Florida red tilapia×Stirling red O. niloticus) males

A comparison was made of some productive traits of Stirling Nile tilapia (wild type) (Oreochromis niloticus, Linnaeus) and red hybrid tilapia (Florida red tilapia× Stirling red O. niloticus) males during a 98‐day grow‐out period. Twenty‐two males from each genetic group with initial weights of 139.0 g for O. niloticus and 207.3 g for the red hybrid were placed in triplicate tanks. The fish were fed with a feed containing 36.8% crude protein. Survival was 97.0% for the red hybrid and 83.3% for O. niloticus. Daily individual weight gains were 2.95 and 2.50 g and final body weights were 473.0 and 348.8 g for the red hybrid and O. niloticus respectively. Fillet yield was similar for both the species, with 33.4% for the red hybrid and 32.0% for O. niloticus. Fresh fillet lipid content was perceptibly less in the red hybrid (0.33%) than in O. niloticus (2.07%). Some benefits of a red low‐fat tilapia genotype are discussed.