鱼体脂肪、蛋白质含量的季节变化对鱼类生活史的影响

鱼体脂肪、蛋白质含量的季节变化是鱼类生物学的一个重要特征,它与洄游、性腺发育、繁殖力、体长等都具有密切的关系,反映了鱼类生活史的不同阶段变化过程.本文根据国内外对鱼类脂肪、蛋白质含量的研究资料,初步阐述了脂肪、蛋白质含量在鱼类洄游、性腺发育、繁殖力等方面所起的作用及机理,指出了研究鱼类能量学对于更好了解鱼类的生物学特征、鱼产品加工业以及制订渔业管理措施等具有重要的意义.     

彭泽鲫(♀)体长、体重、体高与性腺重的相关性

体长、体重、体高是鱼类的重要生物学指标,而性腺重是衡量鱼类繁殖性能的重要参数。本试验主要研究的是彭泽鲫(♀)繁殖季节其体长、体重、体高,哪个指标与性腺重更具有相关性,从而更能体现卵巢的发育程度,达到在选种过程中更具有针对性的目的。实验通过对实验鱼的体重、体高、体长和性腺重进行测定,然后应用生物统计学原理进行相关性的分析,最后得出结论。结论表明在彭泽鲫的生长过程中,体长、体高、体重与性腺重相关性都极显著。     

温室水泥池养殖乌鳢提早性成熟的原因初探

乌鳢属鳍形目、鳢科鱼类。因其肉质鲜美．生长速度快，生活能力强，病害少，死亡率低。便于活鱼运输，而深受养殖户欢迎。目前，乌鳢养殖正在由农村沟塘的半精养方式向水泥池精养方式发展。 据报道，在自然条件下，雌性乌鳢一般２冬龄、体长３０ｃｍ左右时性腺发育成熟，也有个别的１龄雌鱼性腺已发育成熟。在养殖过程中发现，温室水泥池中养殖的乌鳢性成熟年龄有所提前。不足１龄的，体长超过３０ｃｍ，体重 ５００ｇ以上的个体，性腺全部发育成熟，经人工催产可以产卵。 造成性早熟的原因．大致有３个方面： 第一方面，长期摄食高蛋白、高…     

长江刀鲚性腺发育的组织学研究

在长江的南通及安庆江段捕捞刀鲚样本，对样本进行各种常规生物学数据的测量，并对解剖标本的性腺用Bouin氏液进行固定保存后，将性腺制作成组织切片，通过切片观察，了解洄游至南通及安庆江段的刀鲚性腺发育的状况。切片观察表明，刀鲚自当年2-3月洄游入长江后，不断溯江而上，在南通江段性腺发育处在II-III期，历经3-4个月洄游到达安庆江段，其性腺由入江时的Ⅱ-Ⅲ期，逐渐发育到Ⅳ-Ⅴ期。切片观察还表明，在不同洄游群体中，不同个体的卵巢发育程度不一致，有些发育的较快，有些稍慢，但对于雄性个体来说，洄游到安庆江段后，90％以上已达到成熟阶段。此外，文中还对发育中的卵细胞形态结构进行了详细描叙。     

乌鳢池塘网箱规模化人工繁殖技术研究

乌鳢俗称才鱼、黑鱼,是一种以小型鱼类为食物的经济价值,营养价值和医学价值均较高的淡水名贵鱼类.2006年9月至2007年6月,笔者在江西省余干县益人公司乌鳢规模化繁育基地采取池塘中设置网箱,利用网箱进行乌鳢规模化人工繁殖技术实验研究,摸索出一套实用可行的乌鳢规模化人工繁殖技术模式,取得了预期的效果.     

我国鲆鲽类生殖内分泌研究进展

鱼类的生殖和苗种繁育是鱼类养殖业持续健康发展的必要前提和关键技术基础之一,是海洋生物技术的重要研究领域.近年来,我国北方沿海鱼类繁殖生理主要围绕鲆鲽类“下丘脑-垂体-性腺轴”的组织结构特征、性腺发育规律、性类固醇激素、生殖相关功能基因内分泌调控机制等方面开展了较系统的研究.本文重点介绍主要养殖鲆鲽类“下丘脑-垂体-性腺轴”中表达的重要功能基因的研究进展,并综述了鲆鲽类生殖相关组织的结构及其内分泌系统特征、性腺发育的生理特性及其与环境因子和激素诱导的关系、性类固醇激素的表达变化规律及其与水温及光周期调控关系等.旨在为鲆鲽类生殖活动的精准调控和建立苗种繁育新技术提供参考.     

雌性特异蛋白复合物促进鱼类性腺发育及提高孵化率的研究

我们从1980年起开始探索鱼类性腺发育和卵子发育过程中的化学变化,并进行了鱼类血液化学和血液生理学的研究,发现鲫鱼、鳊鱼、罗非鱼、梭鱼的血清蛋白中,雌鱼血清多1条或2条蛋白带,而雄鱼的血清蛋白则未发现此带。同时我们对鱼的性腺发育及卵子成熟过程中物质代谢进行了     

配合饲料养殖月鳢试验

月鳢 (Ｃｈａｎｎａａｓｉａｔｉｃａ)是鳢科鱼类的一种 ,其价格高于乌鳢 4～ 6倍 ,已成为开发养殖的新品种。目前对鳢科鱼类的研究多集中在乌鳢 ,而对月鳢的研究仅限于一般生物学特性、人工繁殖、养殖等 ,还未见有关月鳢营养及配合饲料方面的研究报道。月鳢属于动物食性的鱼类 ,目前养殖多用动物鲜活饵料如小鱼、河蚌、蚯蚓等 ,由于动物饵料缺乏 ,一定程度上限制了月鳢养殖的发展。为此 ,我们 1 996～ 1 999年在进行月鳢生物学习性、人工繁殖研究的基础上 ,进行了月鳢配合饲料的研制 ,并进行了用配合饲料饲养月鳢的养殖试验 ,报道如下。1　…     

黄姑鱼的生物学特征和养殖生态学的研究现状及养殖前景

黄姑鱼是一种具有较高经济价值的海水鱼类,在我国浙江、福建地区展现了良好的养殖前景。本文从生物学特性、繁育生物学和养殖生态学等方面论述了黄姑鱼的形态特征、生活习性及亲鱼的性腺发育规律和人工调控、胚胎发育、早期形态和发育特征、人工孵化、育苗、养殖等基础理论和实践成果,并对存在问题以及其养殖和产业化前景进行了分析。     

配合饲料养殖月鳢试验

月鳢(Channa asiatica)是鳢科鱼类的一种,其价格高于乌鳢4～6倍,已成为开发养殖的新品种.目前对鳢科鱼类的研究多集中在乌鳢,而对月鳢的研究仅限于一般生物学特性、人工繁殖、养殖等,还未见有关月鳢营养及配合饲料方面的研究报道.月鳢属于动物食性的鱼类,目前养殖多用动物鲜活饵料如小鱼、河蚌、蚯蚓等,由于动物饵料缺乏,一定程度上限制了月鳢养殖的发展.为此,我们1996～1999年在进行月鳢生物学习性、人工繁殖研究的基础上,进行了月鳢配合饲料的研制,并进行了用配合饲料饲养月鳢的养殖试验,报道如下.     

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.