短蛸自溶中组织蛋白酶L样蛋白酶的活性及分布变化

采用紫外线照射诱导短蛸自溶,检测腕部肌肉组织可溶性蛋白及可溶性胶原蛋白含量变化,监测内源总蛋白酶及内源组织蛋白酶L样蛋白酶活性变化,并应用免疫组织化学法揭示组织蛋白酶L样蛋白酶的组织分布变化。结果显示,短蛸经紫外线照射后,状态迟钝,机体瘫软,表皮及皮下组织发生黏液化,表明发生自溶。随着自溶时间的延长,可溶性总蛋白及可溶性胶原蛋白含量逐渐增加,表明结构蛋白发生降解;单位质量组织的内源蛋白酶总活力及组织蛋白酶L样蛋白酶活力逐渐上升;组织蛋白酶L样蛋白酶在自溶前的短蛸腕部肌肉组织中的分布具有不均一性,肌小梁中分布密集,肌纤维中分布稀疏。随着自溶的进行,酶染色位点逐渐分散、消失,表明组织蛋白酶L样蛋白酶在组织中发生了扩散。本研究表明以组织蛋白酶L样蛋白酶为代表的内源蛋白酶参与组织自溶。     

太湖银鱼产量与水位关系的数理统计分析

<正> 银鱼是太湖名产,为我国主要出口水产品之一。一般年产100～200万斤,约占太湖每年总渔产量的5～10%,在太湖捕捞渔业中占有一定地位。从5月中、下旬至6月中、下旬每年银鱼汛期中的产量通常占全年银鱼总产量的70%以上。太湖银鱼共有四种,即大银鱼(Protosalanx hyalocranius Abbott)、太湖短吻银鱼(Neosalanx tangkahkeii taihuensis Chen)、寡齿短吻银鱼(Neosalanx     

安徽霍邱城东湖太湖新银鱼的胚胎发育

太湖新银（Neosalanx taihuensis Chen,以下简称银鱼）原名太湖短吻银鱼,又叫小银鱼,面条鱼,隶属鲑形目（Salmoniformes）胡瓜鱼亚目（Osmeroidei）银鱼科（Salangidae）新银鱼属。     

三峡库区3种银鱼线粒体DNA细胞色素b基因序列多态性分析

对三峡库区大银鱼(Protosalanx chinensis)、太湖新银鱼(Neosalanx taihuensis)和短吻间银鱼(Hem isalanxbrachyrostralis)共78尾个体的Cyt b基因全序列(1141bp)进行了分析。结果显示,序列有16个变异位点,总变异率为1.4%,其中13个为简约位点。大银鱼的32尾样本有6个单倍型,太湖新银鱼32尾样本有5个单倍型,短吻间银鱼14尾样本中有3个单倍型。大银鱼、太湖新银鱼和短吻间银鱼的单倍型多样性指数(h)分别为0.804±0.032,0.671±0.061,0.385±0.149;核苷酸多样性指数(π)分别为0.00146±0.00009,0.00228±0.00024,0.00067±0.00026。3种银鱼群体的遗传距离在0.12461~0.23796之间,净遗传距离在0.12274~0.24418之间。基于Cyt b基因序列,利用K imura-2模型构建的NJ树表明:大银鱼与太湖新银鱼种群的亲缘关系最近,两者与短吻间银鱼种群的亲缘关系较远。研究结果表明,三峡库区3种银鱼的遗传多样性低。     

对湖南银鱼移植增殖工作的反思

银鱼素有"水中白金"之称,是我国名贵的小型经济鱼类,具有较高的经济价值,是出口的重要水产品之一。鲜银鱼国内收购价为3－8万元八,出口价为2－4万美元八。洞庭湖区历来是银鱼的生产基地,据调查,有太湖短吻银鱼、寡齿短吻银鱼、长江银鱼、大银鱼;银鱼产卵场门处,有相当产量。仅以玩江市为例,1928年年产鲜银鱼就达90t。但随着湖床淤积和变迁,水质污染以及酷渔滥捕,致使有名的白沙长河银鱼产卵场已不复存在。目前银鱼资源已近绝迹,产量也无统计。l银鱼移植增殖工作的由来1979年中科院南京地理所将太湖新银鱼授精卵移入云南滇池（面…     

辽宁省铁甲水库发现银鱼

1982年春季辽宁省水库调查队发现东沟县铁甲水库有银鱼栖息，1983年5月，又派人对该库及鸭绿江银鱼作了进一步调查研究．经鉴定，在铁甲水库生活的银鱼为乔氏短吻银鱼(Neosaianx Josciani Was ＆ Taka)。     

祖国各地

内蒙岱海移养驯化太湖大银鱼初获成功自云南省滇池移养太湖短吻银鱼获得成功后,北方地区曾先后多年进行了引入太湖短吻银鱼的试验,但至今未获得生产性成效。占太湖银鱼总产50%以上的太湖大银鱼,是出口创汇的经济鱼类之一。这是一种一年生小型鱼类,比较耐寒。苏州蚕桑专科学校(水产专业)与内蒙古水产研究所合作,以大银鱼作为北移对象,并选择     

银鱼漫谈

银鱼属鲱形目、银鱼科,因形似玉簪、细嫩透明、洁白如银而得名。安徽有4种银鱼:大银鱼、前颌间银鱼、太湖新银鱼及长江银鱼。人们常说的银鱼主要指太湖新银鱼(原称太湖短吻银鱼),体长约70毫米,俗称小银鱼,古称灰残鱼、白小。大银鱼,俗称面鱼,体长约170毫米,古称残鱼。     

梅童鱼内源蛋白酶自水解工艺的优化

为提高海捕低值鱼加工利用率,合理利用鱼糜及鱼糜制品加工中的副产物,充分利用鱼类自身内源酶,寻求低值鱼精深加工的低碳高效利用,以梅童鱼(Collichthys lucidus)为研究对象,利用鱼类自身的内源蛋白酶将鱼体内的蛋白质酶解,在自然p H条件下,观察了液料比、自溶温度、时间对梅童鱼蛋白水解的影响,以可溶性蛋白/总蛋白的值为响应值,采用响应面分析优化自溶条件。通过求解回归方程得到的最优自溶条件为:液料比3.4,温度53℃,时间267 min。经过验证,可溶性蛋白/总蛋白的值为18.35%,与回归方程的预测值18.55%相比,相对误差1.1%,说明模型能较好地预测自溶过程中可溶性蛋白/总蛋白的值。在此条件下,测得水解度为15.84%,过0.45μm微滤膜蛋白质量比为9.83%。研究表明,该水解工艺可为生产鱼露、活性肽、氨基酸等提供技术依据。     

太湖短吻银鱼在宽甸安家落户

辽宁省宽甸满族自治县为了充分发挥水面资源优势,大面积发展水产养殖业,增加出口创汇鱼产品,于今年4月中旬移植江苏无锡太湖的短吻银鱼。移植第一阶段获得成功,整个移植     

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).     

Evaluation of a Fast Method Based on the Presence of Two Restriction Sites in the Mitochondrial ND5 (mt ND5) Gene for the Identification of Scomber Species

The purpose of this work was to evaluate the suitability of a method based on the presence of two restriction sites (for Hae III and Hindf I) in the mitochondrial NADH dehydrogenase subunit 5 (mt ND5) gene to identify Scomber species. The evaluation was performed on 144 reference and market samples by sequencing of the entire 505-bp fragment of the mt ND5 gene and of a 464-bp fragment of the Kocher fragment of the cytochrome b gene (mt Cytb). Sequence analysis of any of the two fragments allows the identification of each of the four Scomber species, but S. japonicus and S. colias had the same restriction sites at the ND5 amplicon and would not have been differentiated by this analysis. Similarly, loss of the Hae III site in some S. scombrus individuals would have misidentified them as not being Scomber. All the market products were correctly labeled except one acquired in Spain labeled as originating in the Atlantic and containing S. japonicus.     

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.