利用中国明对虾单对杂交亲本及其F↓（2）群体构建RAPD遗传连锁图谱

由中国明对虾(Fenneropenaeus chinensis)单对杂交亲本(G♀和G♂)及其F2为作图群体,构建了中国明对虾RAPD分子标记的遗传连锁图谱。109个引物共产生284个符合孟德尔分离规律的位点,符合1∶1孟德尔分离类型的位点共234个,符合3∶1孟德尔分离类型的位点50个。利用拟测交理论分别构建中国明对虾雌虾、雄虾的遗传连锁图谱。107个1∶1分离标记分布于雌虾连锁图谱中,包括31个连锁群,图谱总长度为1 406.1 cM,所有标记间的平均间隔为18.5 cM;91个1∶1分离标记分布于雄虾连锁图谱中,包括26个连锁群,图谱总长度为1 187.7 cM,所有标记间的平均间隔为18.27 cM;利用F2自交模型构建了雌虾和雄虾共同的分子标记,35个3∶1分离标记分布于雌雄共有的连锁图谱中,包括10个连锁群,图谱总长度为432.9 cM,所有标记间的平均间隔为17.3 cM。     

三疣梭子蟹遗传连锁图谱的初步构建

利用AFLP和SSR标记技术结合"拟测交"策略,以三疣梭子蟹莱州湾、舟山野生群体杂交(1♂×3♀)产生的F2代家系为作图群体,初步构建了三疣梭子蟹雌、雄性遗传连锁图谱。用经过筛选的60对AFLP引物和3对SSR引物对亲本及108个F2代个体进行遗传分析,共得到母本分离标记214个,其中155个标记(AFLP标记153个,SSR标记2个)符合1∶1孟德尔分离规律;父本分离标记195个,139个标记(AFLP标记138个,SSR标记1个)符合1∶1孟德尔分离规律。雌性图谱包括100个遗传标记,分布在9个连锁群,6个三联体,15个连锁对,图谱总长度为1544cM,标记平均间隔22.0cM,总覆盖率为52.9%。雄性图谱包括71个遗传标记,分布在6个连锁群,6个三联体,11个连锁对,图谱总长度1174.2cM,标记平均间隔24.0cM,总覆盖率为49.5%,图谱中遗传标记分布比较均匀。     

牙鲆遗传连锁图谱的构建

利用基因组测序得到的大量微卫星序列,以681383B为父本、6812E36为母本杂交获得的F1为作图群体,构建了牙鲆(Paralichthys olivaceus)微卫星标记(SSR)遗传连锁图谱。雌雄图谱共定位SSR标记529个,其中雄性连锁图谱包括418个标记,分布在24个连锁群上,总长度1 418.1 cM,标记平均间隔3.62 cM,图谱覆盖率为88.7%;雌性连锁图谱包括437个标记,分布在24个连锁群上,总长度1 298.1 cM,标记平均间隔为3.16 cM,图谱覆盖率为89.1%。牙鲆中密度遗传图谱的构建为QTL分析以及分子标记辅助育种进一步奠定基础,并可以有效推动牙鲆的遗传改良工作,推动牙鲆养殖业的可持续发展。     

坛紫菜遗传连锁图谱的构建

以野生型坛紫菜纯系(♀)和红色型坛紫菜纯系(♂)作为杂交亲本,结合四分子分析法及单个体细胞克隆的丝状体途径,创建了由157个株系组成的坛紫菜DH作图群体,并用经过筛选的24对SRAP引物和16对SSR引物对父母本及作图群体各株系进行双标记分析,获得了224个多态性标记,其中157个标记符合孟德尔分离规律。根据标记间的连锁规律,首次构建了坛紫菜的分子遗传连锁图谱,所构建的遗传图谱由包含124个标记(含SRAP标记104个,SSR标记20个)的5个连锁群组成,总长度为879.2cM,平均标记间隔为7.09cM,各个连锁群长度为134.2～213.6cM,包含标记18～31个。最后采用3种不同方法计算得到坛紫菜的估计基因组长度平均为955.3cM,由此得到坛紫菜遗传连锁图谱的基因组覆盖率为92.0%。     

半滑舌鳎微卫星标记遗传连锁图谱的构建

利用全基因组测序方法筛选出微卫星标记,以渤海近海野生个体和人工养殖的半滑舌鳎(Cynoglossus semi-laevis)为亲本交配产生的F1全同胞家系为作图群体,构建了半滑舌鳎雌、雄微卫星标记遗传连锁图谱。用320对引物对父母本和92个F1个体进行遗传分析,共得到288个分离标记,其中包含112个偏分离标记(P<0.05)。其中雌性框架图包含242个标记,分布在21个连锁群上,总长度1 311.9 cM,标记间平均距离为4.9 cM,图谱覆盖率为83.3%;雄性框架图定位标记218个,21个连锁群,总长度1 316.2 cM,标记间平均距离为5.5 cM,覆盖率为82%。半滑舌鳎遗传连锁图谱的构建为半滑舌鳎重要经济性状QTL定位、分子标记辅助育种和性别控制奠定了重要基础。     

应用SSR和SRAP标记构建青虾遗传连锁图谱

采用SSR和SRAP标记结合拟测交策略构建青虾(Macrobrachium nipponense)遗传连锁图谱。共有175个标记(含27个SSR、148个SRAP标记)分布在53个连锁群上。每个连锁群含2~8个标记,其中不少于3个标记的连锁群有35个,连锁对18个,平均每个连锁群的标记数为3.3个;连锁群长度在6.7~91.2 cM之间,相邻标记间最大间隔为49.0 cM,最小为1.4 cM,平均间隔为13.1 cM。青虾框架图谱长度为997.2 cM,图谱观察总长度为2 270.5cM,根据估算,青虾遗传连锁图谱预期长度为4 380.6 cM,图谱的覆盖率为51.83%。本研究构建了青虾遗传连锁图谱,该图谱也是淡水虾蟹类第一张遗传连锁图谱,可为青虾QTL定位、基因克隆、遗传选育等提供指导,并为进一步构建高密度的青虾遗传连锁图谱奠定了基础。     

中国对虾连续两代的DNA随机扩增多态性及其遗传规律分析

为评估DNA随机扩增多态性标记在中国对虾遗传连锁图谱构建中的应用前景,利用中国对虾单对交配亲本及其子二代材料,对RAPD标记及其遗传规律进行了研究。22条RAPD随机引物扩增结果的统计分析表明,标记在中国对虾F2的遗传规律可归为不分离标记和分离标记:不分离标记,指在亲本和后代中均不分离的标记,占总位点的54.1%;分离标记占总位点的45.9%。其中,分离标记又包括符合孟德尔遗传分离的标记、偏离孟德尔遗传分离标记和异常分离标记。符合孟德尔分离的标记中,分离比例为3∶1的标记占分离标记的14.7%;总的1∶1标记占分离标记的64.7%;偏离孟德尔分离和异常分离的标记分别占分离标记的11.7%和8.9%。在这些分离的标记中,有76.5%的位点在"双假测交理论"的策略中适合构建中国对虾的遗传连锁图谱,这为以中国对虾F2为作图群体,并利用RAPD标记构建中国对虾遗传连锁图谱提供了理论支持。     

中国对虾遗传连锁图谱的构建

利用RAPD、SSR和AFLP三种标记技术结合"拟测交"策略,以中国对虾"黄海1号"雌虾与野生雄虾作为亲本进行单对杂交产生的F1家系为作图群体,初步构建了中国对虾雌、雄性遗传连锁图谱.对460个RAPD引物和44对SSR引物进行筛选,共选出61个.RAPD和20对SSR引物,结合88对AFLP引物组合对父母本和82个F1个体进行了遗传分析.共得到783个分离标记(RAPD标记237个,微卫星标记45个,AFLP标记501个),761个标记用于连锁分析.雌性图谱包括40个连锁群和15个三联体,20个连锁对,标记间平均间隔为12.5 cM,图谱共覆盖2835.5 cM,覆盖率为73.5%;雄性图谱包括41个连锁群和6个三联体,12个连锁对,标记间平均间隔为11.9 cM,图谱共覆盖2776.7 cM,覆盖率为73.3%.中国对虾遗传图谱的构建为其分子标记辅助育种、比较基因组作图及数量性状位点(QTL)的定位与克隆奠定了基础.     

中国对虾近交两代的DNA随机扩增多态性及其遗传规律分析

为评估DNA随机扩增多态性标记在中国对虾遗传连锁图谱构建中的应用前景,利用中国对虾单对交配亲本及其子二代材料,对RAPD标记及其遗传规律进行了研究。22条RAPD随机引物扩增结果的统计分析表明,标记在中国对虾F2的遗传规律可归为不分离标记和分离标记：不分离标记,指在亲本和后代中均不分离的标记,占总位点的54.1%;分离标记占总位点的45.9%。其中,分离标记又包括符合孟德尔遗传分离的标记、偏离孟德尔遗传分离标记和异常分离标记。符合孟德尔分离的标记中,分离比例为3:1的标记占分离标记的14.7%;总的1:1标记占分离标记的64.7%;偏离孟德尔分离和异常分离的标记分别占分离标记的11.7%和8.9%。在这些分离的标记中,有76.5%的位点在“双假测交理论”的策略中适合构建中国对虾的遗传连锁图谱,这为以中国对虾F2为作图群体,并利用RAPD标记构建中国对虾遗传连锁图谱提供了理论支持。     

鲢鳙杂种亲本连锁图标记加密和共线性比较

鲢(Hypophthalmichthys molitrix)与鳙(Aristichthys nobilis)杂种的养殖性能优于亲本,在水产养殖中利用广泛.为促进鲢、鳙遗传资源管理、经济性状定位等研究,已构建了鲢鳙种间杂种亲本的遗传连锁图,但图谱以AFLP标记为主,利用范围有限.为提高图谱质量和可用性,本研究采用新开发的微卫星标记加密了鲢鳙杂种亲本连锁图.雌性亲本鲢的连锁图标记总数从153增加到288(包括新开发微卫星标记93个),雄性亲本鲢的连锁图标记总数从271增加到511(包括新开发微卫星标记136).鳙图谱总长度从852.0 cM增加到965.8 cM,鲢图谱总长度从952.2 cM增加到1049.6 cM.鲢、鳙图谱共线性比较甄别出22个同缘连锁群,标记排列只存在轻微重排现象.亲本间共享的76个微卫星标记界定的标记间隔总长度在亲本间无差异(雌:雄＝1:1),与鳞鲢种内杂种亲本共享微卫星标记界定间隔的总长度雌雄比(1:0.45)显著不同.与模拟自然受精(种内杂种)相比,混精受精(种间杂种)可增加雄性亲本基因组范围的重组率.鲢鳙形态相似,染色体组型相同,杂种可育,鲢鳙杂交对重组率没有影响或影响很小.根据研究结果,认为混精授精回避了精子竞争,强化了全基因组重排,不利于新形成的和已有的优良单倍型的保留,是鲢鳙养殖性能退化的原因之一.     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).     

Nitrogenous waste excretion and accumulation of urea and ammonia inChalcalburnus tarichi (Cyprinidae), endemic to the extremely alkaline Lake Van (Eastern Turkey)

The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I^–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg^–1 fish·h^–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g^–1·ml^–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min^–1·g^–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min^–1·g^–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.     

Imported ornamental fish are colonized with antibiotic‐resistant bacteria

There has been growing concern about the overuse of antibiotics in the ornamental fish industry and its possible effect on the increasing drug resistance in both commensal and pathogenic organisms in these fish. The aim of this study was to carry out an assessment of the diversity of bacteria, including pathogens, in ornamental fish species imported into North America and to assess their antibiotic resistance. Kidney samples were collected from 32 freshwater ornamental fish of various species, which arrived to an importing facility in Portland, Oregon from Colombia, Singapore and Florida. Sixty‐four unique bacterial colonies were isolated and identified by PCR using bacterial 16S primers and DNA sequencing. Multiple isolates were identified as bacteria with potential to cause disease in both fish and humans. The antibiotic resistance profile of each isolate was performed for nine different antibiotics. Among them, cefotaxime (16% resistance among isolates) was the antibiotic associated with more activity, while the least active was tetracycline (77% resistant). Knowing information about the diversity of bacteria in imported ornamental fish, as well as the resistance profiles for the bacteria will be useful in more effectively treating clinical infected fish, and also potential zoonoses in the future.     

Effect of iodophor disinfection of non‐hardened Salmo trutta eggs on their bacterial and fungus load

This study investigated the efficiency of iodophor disinfection (135 ppm active iodine for 15–30 min) of non‐hardened Salmo trutta eggs against different groups of bacteria and against fungus. Egg samples were taken from non‐disinfected and from disinfected eggs, microorganisms were cultured on specific nutrient media and their mass was measured by turbidimetric methods. Bacteria and fungus mass of non‐hardened eggs could be reduced but not eliminated by iodophor disinfection with 135 ppm active iodine for 15 min. The extent of reduction was 47–65% (Experiment 1). The efficiency of disinfection increased with disinfection time as the reduction in bacteria and fungus mass was 40–55% after 15 min and 58–74% after 30 min (Experiment 2). Disinfection efficiency of iodophor solution diluted in water (reduction 49–57%) and of iodophor solution diluted in sodium chloride solution iso‐osmolar to the oocytes (reduction 52–61%) was similar (Experiment 3). The reduction in bacteria and fungus mass was persistent as it was 39–72% lower in embryos deriving from disinfected eggs than in embryos deriving from non‐disinfected ones (Experiment 4). In conclusion, the tested disinfection method is inadequate to eliminate pathogens completely but it could positively influence immune defence of eggs and embryos.     

Influence of the antibacterial herbs, Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia on the survival, growth and bacterial load of Penaeus monodon post larvae

The indiscriminate use of antibiotics and chemicals in shrimp hatcheries has led to biomagnification and that in turn could lead to rejection of a whole consignment. The application of the bioencapsulation technique as a tool for curative treatment in shrimp larvae was investigated. Herbs having antibacterial properties such as Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia (methanolic extracts) were bioencapsulated in Artemia and fed to Penaeus monodon post larvae PL 1–25. The post larvae were reared in a medium inoculated with pathogenic bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Vibrio sp. Post larvae reared in the non-inoculated water and fed with non-enriched Artemia exhibited 90% survival, highest specific growth rate (12.43%) and reduced bacterial load. P. monodon reared in the bacterial inoculated water and fed with the non-enriched Artemia exhibited the lowest survival (10–30%), specific growth rate (8.42–9.1%) and increased bacterial load (2.86 × 10³ to 3.76 × 10⁵ cfu/g). The methanolic extracts of the herbs helped to increase survival and specific growth rate and reduced bacterial load in the P. monodon culture system. Among the three herbal extracts, P. corylifolia enriched Artemia fed post larvae showed the tendency to higher survival (>50%), growth rate (11.5 averaged) and low bacterial load (1.12 × 10⁵ cfu/g). This revised version was published online in August 2006 with corrections to the Cover Date.