急性盐度胁迫对日本黄姑鱼肌肉组织转录组的影响

盐度是影响鱼类各种生理活动的重要环境因素,为探讨急性盐度胁迫对经济海水鱼类日本黄姑鱼基因表达水平的影响,实验基于Illumina HiSeq^TM 2500高通量测序平台,对不同盐度条件下日本黄姑鱼幼鱼肌肉组织进行转录组测序并开展生物信息学分析。结果显示,高盐组、低盐组和对照组分别获得46 379 598、36 130 844和38 715 820条Clean reads,总碱基数分别为5.27、4.87和5.53 GB。经组装得到91 667条转录本,去冗余后拼接得到61 601条Unigenes。与对照组相比,高盐组和低盐组分别有2 230和1 377个差异Unigene上调,1 959和2 447个差异Unigene下调,随机选取6条差异表达基因进行实时荧光定量PCR验证,结果与转录组测序一致。通过对显著差异表达基因进行筛选,在高盐组和低盐组中分别发现21和41个差异表达基因与离子通道相关,共有的离子通道相关基因为15个,其中14个基因表达趋势一致。而在高盐组和低盐组发现的离子转运体基因分别为6和10个。GO功能富集分析发现,差异基因显著富集在蛋白酶体、补体激...     

虾夷扇贝外套膜和肾脏组织cDNA文库构建以及EST的初步分析

利用SMARTcDNA文库构建试剂盒首次构建了健康虾夷扇贝(Mizuhopecten yessoensis)外套膜和肾脏2种组织的cDNA文库。2个文库容量分别为2.30×106CFU/mL和1.20×106CFU/mL,重组率均超过98%,平均插入片段长度均大于1kb,文库质量符合标准要求。将随机选取的4009个克隆进行5′端测序,得到3884个有效序列(外套膜923个,肾脏2961个),测序成功率96.9%。经过质量控制和拼接,共得到2007条单基因簇(Unigenes),包含363个序列重叠群(Contigs)和1644条单一序列(Singletons)。通过BLASTx和BLASTn搜索比对,共有659个Unigenes(外套膜157个;肾脏502个)获得了基因注释(Ee-5),占Unigene总数的32.84%。对Unigene的功能和分类进行了初步分析,发现多种与免疫相关的基因,如凝集素、超氧化物歧化酶、溶菌酶、大防卫素等。利用SSRIT在线工具对2007条Unigene查找微卫星,发现有69个EST中含有微卫星序列,其中40个可以用于引物设计。虾夷扇贝cDNA文库的成功构建,为进一步的EST分析、功能基因的表达和克隆、多态性EST-SSR的筛选以及虾夷扇贝分子遗传学研究、种质资源评价和分子选育等奠定了基础。     

脊尾白虾对低盐胁迫响应的转录组学分析

转录组测序可在各种环境条件下对物种进行高通量测序,通过基因结构分析和功能注释,探讨特定条件下相关基因的功能和表达情况。该研究分别获取低盐胁迫组(盐度0.2)和自然海水组(盐度31)脊尾白虾(Exopalaemon carinicauda)样品,通过Illumina平台进行转录组测序,获得13.92 Gb高质量测序数据,组装得到111 618条转录本和72 734条Unigenes,其中有22 879条Unigenes得到注释,比对到Nr数据库的Unigenes为21 931条;筛选出1 492条脊尾白虾低盐胁迫差异显著表达基因,包括829条上调基因和663条下调基因,其中有810条差异表达基因得到注释。通过差异表达基因GO功能注释和富集分析及KEGG通路富集分析,锁定大量脊尾白虾在自然海水和淡水环境下的差异表达基因,为深入探讨脊尾白虾在低盐胁迫条件下的生理保护机制提供了技术支撑。     

基于RNA-seq技术的江鳕转录组SSR位点信息分析

为开展江鳕(Lota lota)遗传多样性、系统分化分析,开发有效分子标记,采用转录组测序RNA-seq方法,挖掘江鳕微卫星标记。结果显示:通过聚类、从头组装和拼接,获得Unigene共计106 084条。所有的Unigene中,共识别17 619个SSR位点,包含SSR位点的Unigene序列数量为10 893条,占总Unigene的10.27%。江鳕转录组中SSR含量较为丰富,一至六核苷酸重复类型均存在。其中,单核苷酸重复类型的数量最多(7 102个),占总SSR位点数的40.31%。江鳕转录组SSR位点中,以10次重复次数最多,达2 788个位点,占总SSR位点的15.82%。江鳕转录组SSR的片段长度从10～66 bp均有分布,大部分集中在10～24 bp,占SSR总数的87.24%。     

锦绣龙虾全长转录组测序分析

为了获得锦绣龙虾(Panulirus ornatus)丰富的转录组信息和功能基因,采用PacBio平台的Single Molecule Real-Time测序技术,对锦绣龙虾鳃、肝胰脏、肌肉、胃、肠、脑和心脏混合组织进行全长转录组测序,首次获得锦绣龙虾的全长转录本文库.通过测序拼接和去冗余后共获得13297条Unige...     

哈维氏弧菌感染的杂色鲍全组织均一化cDNA文库的构建

提取了哈维氏弧菌（Vibrio harveryi）感染的杂色鲍（Haliotis diversicolorReeve）总RNA,采用SMART方法合成双链cDNA,并用双链特异核酸酶进行均一化处理。割取0.5~1.0和1.0~3.0kb的片段分别连接pDNR-LIB并转化大肠杆菌（Esherichia coli）,最终构建2种片段大小的杂色鲍全组织均一化cDNA文库。2文库库容均在2.5×105cfu.mL-1左右,PCR检测阳性重组率为100%。随机挑取200个克隆测序,获得高质量EST序列174条。组装后得到149条Unigenes,冗余率为14.37%。序列注释结果表明,有39条Unigene序列与已知基因高度相似。综上所述,文章所建cDNA文库质量良好,可以满足后续研究工作的需要。     

基于转录组测序的大口黑鲈驯食相关SNP开发及其与生长性状的关联分析

大口黑鲈为肉食性鱼类,传统养殖过程中使用大量的冰鲜鱼为饵料,冰鲜鱼的使用不仅增加了养殖成本,而且多余的冰鲜鱼残饵还会给环境带来严重的污染。为了保护环境并降低养殖成本必须减少冰鲜鱼的使用量,本实验以选育适合人工配合饲料饲喂大口黑鲈为研究目标,用人工配合饲料作为饵料驯化大口黑鲈幼鱼,在驯食后14和16 d,测定其体质量、全长、体高等生长指标。同时在大口黑鲈转录组测序分析获得的SNP位点中,选择其所在序列的基因功能与能量代谢有相关性的7个SNP位点进行SNaPshot分型,用SPSS 19.0进行卡方分析标记与生长性状的相关性。结果发现,序列Unigene031044中的C1332G位点、Unigene085384中的A741G位点和Unigene022319中的A284G位点在体质量、全长及体高性状上存在显著差异。这3个SNP位点所在的基因经预测分别与雌二醇17β脱氢酶12B (hsd17b12b)基因、长链酰基辅酶A合成酶家族成员1(acsl1)基因和琥珀酸脱氢酶组装因子2(sdhaf2)基因具有很高的同源性,推测上述3个SNP位点的变异可能影响了基因表达产物对脂肪酸代谢或三羧酸循环的调节功能,与大口黑鲈对人工配合饲料的利用能力存在密切的相关性。本研究筛选得到的与驯食相关的SNP位点为大口黑鲈功能基因多态性的进一步研究,及加快大口黑鲈食性改良与驯化育种的遗传研究提供了科学的参考依据。     

文蛤肠、外套膜和肝胰脏组织 cDNA 文库构建及其 ESTs 序列分析

利用SMART cDNA文库构建试剂盒构建了文蛤(Meretrix meretrix)肠、外套膜和肝胰脏组织的cDNA文库。经测定原始文库滴度分别为2.10×106、1.70×106和1.60×106,重组率高于95%,肠组织文库插入片段长度均大于1000bp,外套膜和肝胰脏组织文库的插入片段长度大于1kb的占87.5%,文库质量符合标准要求。随机选取文库的3168个克隆进行5′端测序,获得高质量表达序列标签(Expressed Sequence Tags,ESTs)3029个(肠:1005,外套膜:1019,肝胰脏:1005),测序成功率95.58%。经质量控制和拼接得到1796个单基因簇(Unigene),其中306个叠联群(Contigs),1490个单一序列(Singletons)。通过Blastx搜索比对、查询和注释分析,共得到已知基因696个(肠:216,外套膜:235个;肝胰脏:245个),占总数38.75%。在1796个单基因簇(Unigene)发现微卫星序列55条,这些存在微卫星位点的序列占整个ESTs数据库的3.1%。     

碱胁迫下“鲟龙1号”(Huso dauricus♀×Acipenser schrenckii♂)鳃组织结构变化及转录表达特征

为探究碱胁迫下杂交鲟“鲟龙1号”(Huso dauricus♀×Acipenser schrenckii♂)的响应机制,本研究设置了淡水组(3.13～3.20 mmol/L)与胁迫组(14.4～16.67 mmol/L),采集鳃进行了组织病理分析,并利用转录组测序技术,进一步分析转录组表达特征。结果显示：高碱胁迫下“鲟龙1号”鳃组织出现明显损伤,鳃小片末端发生肿胀、卷曲和融合,鳃上细胞出现增生和膨大。转录组测序共获得80 422条Unigene,富集到GO数据库的差异表达基因为371个,其中87个基因表达上调,284个基因表达下调,富集到KEGG的代谢通路主要为矿物吸收、近曲小管碳酸氢盐重吸收和胃酸分泌等通路,其中近曲小管碳酸氢盐重吸收为主效应途径,该途径的Nhe3、Atp1a、Atp1b和Gdha基因显著表达下调。综上所述,碱度为14.4～16.67 mmol/L的条件下,“鲟龙1号”幼鱼已发生鳃组织损伤,且矿物质重吸收、钾/钠离子转运与排氨等功能受到影响。     

双须骨舌鱼转录组EST-SSR标记开发与引物筛选

利用MISA软件对双须骨舌鱼(Osteoglossum bicirrhosum)性腺转录组测序获得的188 461条Unigene进行SSR检测,结果在11 917个Unigene中共检测到SSR位点12 578个,其中包含2个及以上SSR位点的Unigene有633个。SSR的发生频率为6.32%,平均分布距离为9 949 bp。在筛选到的SSR位点中,优势重复基序为二核苷酸、三核苷酸和四核苷酸,其中二核苷酸重复基序数量最多,占总数的50.52%。重复基元类型共216种,其中数量最多的类型为二核苷酸重复AC/GT,占总数的20.66%。从所有筛选出的SSR位点中随机选取50个位点并运用Primer Premier 5.0设计引物,共有25对引物成功扩增出特异性产物,并且均在同科的美丽硬仆骨舌鱼(Scleropages formosus)的三个亚种中通用。结果表明,转录组测序产生的EST序列是开发SSR标记的有效来源,开发所得EST-SSR引物可用于双须骨舌鱼及其近缘物种遗传分析、遗传图谱构建以及分子标记辅助育种等工作中。     

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).     

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.     

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.     

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.