不同脂肪源对褶皱臂尾轮虫脂类和脂肪酸组成的影

以褶皱臂尾轮虫（Brachionus plicatilis)为实验动物并设计不同脂肪源饵料，分别为：面包酵母Saccharomyces cerevisice（对照组），微绿球藻Nannochlorpisis oculata(A)，5%大豆磷脂 5%鱼油 90%面包酵母（C）。结果表明：（1）接受不同脂肪源的轮虫的脂肪酸组成显著不同，尤其是高度不饱和脂肪酸（HUFA，20C）含量存在显著差异，说明饵料中HUFA含量对轮虫体内相应脂肪酸的含量有显著影响。投喂饵料C使轮虫的脂类HUFA水平得到了强化，提高了轮虫的营养价值。（2）轮虫脂类的HUFA水平不仅由饵料中脂类的相应脂肪酸组成决定，而且轮虫脂类HUFA的提高和强化效果与饵料中HUFA的化学形态密切相关。甘油三酯型饵料HUFA的强化轮虫效果高于磷脂型的HUFA。（3）将富含HUFA的鱼油直接添加在干性饵料如面包酵母中，而不是通过对鲁油乳化后直接强化轮虫，同样能取得良好的强化效果，且操作简便、不易污染水质，适用于轮虫的规模生产。     

活饵料中n-3高度不饱和脂肪酸对黑鲷仔稚鱼生长和存活的影响

采用乳化油直接添加法,用n－3高度不饱和脂肪酸（n－3HUFA）含量不等的4种乳化油分别强化轮虫、卤虫活饵料,培育4组黑鲷仔鱼和稚鱼,各自历时15d,结果表明,n－3HUFA对黑鲷仔鱼和稚鱼的生长和存活均有重要影响。在该条件下,轮虫体内n－3HUFA含量为0．233％（湿重计）,卤虫体内n－3HUFA含量为4．273％（湿重计）时,仔鱼和稚鱼达到最佳生长和成活率。     

饵料中高不饱和脂肪酸在海水鱼苗培育中的作用

大量研究表明，海水鱼苗对饵料中的某些高不饱和脂肪酸(HUFA)有特殊的需要，如果饵料中缺乏这些HUFA，如DHA(docoaahexaenoic acid 22：6n-3)、EPA(eicosapentaenoic acid 20：5n-3)和AA(arachidonic acid 20：4n-6)，将严重影响其营养价值。主要介绍了HUFA对海水鱼苗的营养和生理作用以及饵料中的各种HUFA水平在海水鱼苗培育中的作用，并且给出了某些海水鱼苗对饵料中HUFA的需要量和各种HUFA之间的适宜比例。     

n-3高不饱和脂肪酸对黑鲷幼鱼生长及脂肪代谢的影响

研究了饲料中不同水平n-3 HUFA（0.79%,0.83%,0.85%,0.88%,0.92%,0.94%;DHA/EPA=2.8/1）对黑鲷幼鱼生长及脂肪代谢的影响。结果显示：（1）黑鲷幼鱼肝体指数（HSI）及腹脂率（IPF ratio）随饲料中n-3 HUFA含量的增加而减小,且于0.92%和0.94%组时显著低于其他各组;脂肪细胞直径呈减小趋势,其中0.94%组显著小于0.85%组;肌肉脂肪含量受n-3 HUFA的影响显著,于0.88%组时达到最低。各组全鱼水份和脂肪含量差异不显著（P>0.05）。肝脏、肌肉及腹腔脂肪组织饱和脂肪酸（∑SFA）和C16∶0含量均随饲料n-3 HUFA水平增加呈下降趋势,而∑n-3 HUFA呈显著上升趋势。各组织中DHA/EPA不受饲料脂肪酸组成的影响。以增重率为参考指标,二次回归分析结果表明,黑鲷幼鱼［（8.08±0.09） g］获得最佳增重时对饲料中n-3 HUFA的需要量为0.87% DM;（2）黑鲷幼鱼肝脏脂肪酸合成酶（FAS）活性及基因表达水平均在n-3 HUFA>0.92%时有显著下降（P<0.05）;腹腔脂肪激素敏感脂肪酶（HSL）活性及基因表达水平均随饲料中n-3 HUFA的添加呈升高趋势（P<0.05）,且高含量n-3 HUFA（0.94%）可使HSL活性增加近一倍。结果表明,饲料中n-3 HUFA通过同步调控脂肪合成与分解两个过程影响黑鲷幼鱼脂肪代谢。     

温室养鳖池底质硝化细菌的分离及其硝化性能的初步研究

通过对温室养鳖池底质硝化细菌的富集，使其浓度达到10^7个／mL，用硅胶平板分离得到硝化细菌纯培养物。经鉴定主要有四种菌：硝化杆菌（Nitrobacter sp.）、硝化球菌（Nitrococcussp.）；亚硝化单胞菌（Nitrosomonas sp.）和亚硝化球菌（Nitrosococcus sp.）。同时，对四种硝化细菌的硝化强度进行了测定，结果依次分别为78.7%、61.8%、74.3%和59.9%。而利用盐酸环丙沙星对硝化细菌硝化性能进行了干扰试验表明，0.4mg/L以上的盐酸环丙沙星，对亚硝化球菌和硝化球菌的硝化强度影响较大；同样浓度的抗生素对亚硝化单胞菌和硝化杆菌的影响相对较小。     

鱼类对脂肪酸需求的新发现

科研人员近期研究发现，蛙科鱼类的大麻哈鱼、银大麻哈鱼、红大麻哈鱼和大鳞大麻哈鱼对18：3必需脂肪酸的需要量为1％。9．5％的高度不饱和脂肪酸（HUFA）可满足其最佳生长所需。鳟鱼的脂肪酸需要量研究表明，加利福尼亚蹲鱼对20：5ω_3和22：6ω_3的需要量高于其他鱼类。白鲑科鱼类的白鲑鱼、高白鲑、齐尔白鲑最佳生长，需要1％的18：3ω_3脂肪酸，将20：5ω_3（0．25％）和22：6ω_3（0．25％）混合使用亦可产生同样的效果。欧洲鳗鲡和日本鳗鲡、鲤、斑点叉尾鲴均需1～2％的18：2ω_3脂肪酸，0．5～1％的HUFA亦能满足其营养需要。尼罗…     

不同开口饵料对江鳕仔鱼生长及存活率的影响

采用海水皱褶轮虫（Brachionus plicatilis）、淡水臂尾轮虫（Bruchionus sp.）（维持有小球藻（Chlorella sp.））、超微粒子饵料、水丝蚓（Tubifex sp.）肉糜、摇蚊幼虫（Chironomus sp.）肉糜五组不同饵料进行江鳕仔鱼开口饵料选择试验。经15 d培育,结果表明：淡水轮虫是江鳕仔鱼最佳开口饵料,生长速度最快,成活率最高（95.42%）。     

饥饿对曼氏无针乌贼肝脏与卵巢脂肪酸组成的影响

在曼氏无针乌贼（Sepiella maindroni）性腺成熟阶段（4～5月）对其进行饥饿处理,以空腹处理组饥饿0d（禁食1d）、饥饿12d（禁食13d）和饥饿24d（禁食25d）为取样时间取其肝脏和卵巢组织进行脂肪酸组成及质量分数测定。结果表明,随着饥饿时问的延长,乌贼体质量下降,肝脏和卵巢萎缩,肝脏中的饱和脂肪酸（SFA）和单不饱和脂肪酸（MUFA）较空腹处理组有显著下降（P〈0．05）,而多不饱和脂肪酸（PUFA）和高不饱和脂肪酸（HUFA）均有显著提高（P〈0．05）。与肝脏相比,乌贼卵巢中的各脂肪酸组成在饥饿12d变化较小,饥饿24d时∑SFA较空腹处理组有极显著下降（P〈0．01）,而∑MUFA、∑PUFA＋∑HUFA和∑n-6 PU—FA显著高于空腹处理组（P〈0．05）。     

达氟沙星在水产养殖中的研究进展

<正>达氟沙星（Danofloxacin）属于第三代动物专用氟喹诺酮类抗菌药物，临床常用甲磺酸达氟沙星。该药作用于细菌的DNA旋转酶亚单位，抑制细菌DNA复制及转录，进而产生杀菌作用。其抗菌谱广，对大肠埃希菌（Escherichia coli）、沙门菌（Salmonella）、胸膜肺炎放线杆菌（Actinobacillus Pleuropneumoniae）、变形杆菌（Proteus sp.）、     

维生素E及脂肪源对大菱鲆非特异性免疫的影响

在大菱鲆饲料中分别添加鲤鱼鱼油及花生油作脂肪源,每种脂肪中添加两个水平的维生素E（8mg／kg和300mg／kg维生素E醋酸酯）,饲养大菱鲆84d,探讨其对大菱鲆非特异性免疫的影响。结果发现,（1）以鲤鱼鱼油为脂肪源的添加高剂量的维生素E能提高大菱鲆血清补体活性,而以花生油为脂肪源的饲料添加高剂量的维生素E不影响大菱鲆血清补体活性;（2）以鲤鱼鱼油和花生油为脂肪源的饲料添加高剂量的维生素E不影响大菱鲆中性粒细胞的吞噬率及白细胞总数;（3）以鲤鱼鱼油为脂肪源的饲料添加高剂量的维生素E能提高大菱鲆的溶茵酶活性,但随着时间推移其影响减弱;（4）饲喂n-3HUFA含量高的饲料,对大菱鲆腹水病的抵抗能力高于n-3HUFA含量低的饲料。     

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.     

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.