南美白对虾卵和无节幼体脂肪酸组成及其与饵料的关系

为探讨南美白对虾 (Penaeusvannamei)在幼体发育过程中对多不饱和脂肪酸的需求及饵料对卵、无节幼体脂肪酸组成的影响 ,对南美白对虾卵和无节幼体脂肪酸的组成进行测定和分析 ,并比较幼体阶段主要脂肪酸含量及其变化。在卵脂肪中占主要比例的脂肪酸为棕榈酸、棕榈油酸、亚油酸、花生四烯酸和DHA ,而在无节幼体中则为棕榈酸、棕榈油酸、亚油酸、花生四烯酸、EPA和DHA。在从卵到无节幼体的发育过程中 ,除EPA和DHA占总脂肪酸比例有较明显的上升外 ,其他脂肪酸所占比例均有不同程度的变化 ,总体变化特点为饱和脂肪酸的比例逐渐下降 ,而多不饱和脂肪酸的比例上升。亲虾饵料沙蚕 (Nereisspp .)的脂肪酸组成分析表明 ,沙蚕与卵及无节幼体脂肪酸的组成具有一定的相关性。     

中国对虾（Penaeus orientalis Kishinouye）的几种必需脂肪酸营养价值的比较研究

用四种试验饵料，其中分别含有１％高纯度的ω－３及ω－６不饱和脂肪酸（亚油酸Ｃ１８∶２ω６、亚麻酸Ｃ１８∶３ω３、花生四烯酸Ｃ２０∶４ω６、二十二碳六烯酸Ｃ２２∶６ω，ＤＨＡ）以及一种对照饵料含有５％棕榈酸Ｃ１６∶０和油酸Ｃ１８∶１ω９混合物对中国对虾（ＰｅｎａｅｕｓｏｒｉｅｎｔａｌｉｓＫｉｓｈｉｎｏｕｙｅ）幼虾进行了为期３２天的投喂试验，从成活率、蜕皮次数及增重等实验结果可见二十二碳六烯酸（ＤＨＡ）对中国对虾幼虾具有最高的营养价值。同时，对海捕和人工养殖的中国对虾的脂肪酸组成进行了比较，两者都含有大量的ω－３系列的高度不饱和脂肪酸；但是与海捕虾相比较，人工养殖对虾的ＤＨＡ含量较低，而亚油酸含量较高。上列结果表明在对虾饵料中补充富含ＤＨＡ的脂肪源将有效地促进对虾增产。     

野生及人工养殖的中国对虾（Penaeus Chinensis）的脂肪酸组成的分析及比较研究

通过对野生及人工养殖的中国对虾的肌肉、肝胰脏、性腺及卵的脂肪酸的分析比较，结果显示野生及人工养殖的中国对虾都含有大量的ω－３系列高度不饱和脂肪酸，这与其它海洋甲壳类的脂肪酸组成相类似；与野生的中国对虾相比较，人工养殖对虾的各组织及卵含有较高比例的亚油酸及较低比例的二十二碳六烯酸（ＤＨＡ）。野生与人工养殖的中国对虾在脂肪酸组成上的这一差异，是由于它们的生态环境及所摄食物的不同所造成的。从我们先前的实验证明ω－３系列和ω－６系列长链高度不饱和脂肪酸是中国对虾的必需脂肪酸，其中尤以ＤＨＡ最为重要，对于幼虾的生长及亲虾的成熟都是必需的。可见在人工养殖中国对虾的配饵中添加富含ＤＨＡ的脂肪源将是提高人工养殖对虾产量和质量的一个重要途径。     

三角褐指藻不同藻株脂肪酸组成的研究

１９９６￣１９９８年对上海、浙江和厦门的三角褐指藻进行分离克隆,比较了其中５个藻株在相同培养条件下的脂肪酸组成及培养液淡化对其脂肪酸组成的影响。结果表明,５个藻株的脂肪酸组成特征基本一致,均具有高比例的肉豆蔻酸（１４：０）、棕榈酸（１６：０）,棕榈油酸（１６：１）,十六碳二烯酸（１６：２）和ＥＰＡ（２０：５）,只有低含量的ＤＨＡ（２２：６）,花生烯酸（２０：１）和１８碳脂肪酸,但不同藻株的脂肪酸含     

高度不饱和脂肪酸对中国对虾亲虾的产卵和卵质的影响

用高度不饱和脂肪酸组成和含量不同的四种饲料饲养中国对虾亲虾以研究高度不饱和脂肪酸对中国对韪亲虾产卵及卵质的影响。试验采用脂肪酸组成模式不同的Ｔｉ鱼油,亚麻油,玉米油和猪油为脂肪源配制的饲料对产卵前的亲虾进行６０天的投喂试验,测定了不同脂及到脂肪酸组成的饲料对亲虾产卵量,孵化率和卵脂肪酸组成的影响,并经回归分析结果表明,卵脂肪中的２０：５ω３与产卵量,２２：６ω３与孵化率有相关关系,表明了ＥＰＡ,Ｄ     

中国对虾卵巢发育过程中脂肪酸组成的分析及比较研究

通过分析中国对虾亲虾在卵巢发育的不同阶段的卵巢、肝胰脏和肌肉的脂肪酸组成来评估中国对虾在性腺成熟过程中对脂质的需要。从中国对虾亲虾不同组织的脂肪酸组成可见,棕榈酸(16:0)、棕榈油酸(16:1ω7)、油酸(18:1ω9)、二十碳五烯酸(20:5ω3,EPA)及二十二碳六烯酸(22:6ω3,DHA)占主要比例,这与其它海洋甲壳类的脂肪酸组成相类似。中国对虾亲虾的主要脂肪酸组成比例与日本对虾亲虾的主妥脂肪酸组成比例相近似。中国对虾亲虾在不同的卵巢成熟期同一器官中的主要脂肪酸组成比例没有明显的差别,而不同组织的主要脂肪酸组成中都含有大量的ω-3系列的高度不饱和脂肪酸。从成熟卵巢的脂肪酸组成中含有高比例的EPA、DHA含量可见,EPA、DHA在亲虾性腺发育过程中的必需性。     

真鲷幼鱼的EPA,DHA需求量研究

通过向真鲷幼鱼饵料中分别添加０．２％、０．５％和１％的ＥＰＡ、ＤＨＡ以及两种混合脂肪酸,以豆油为基础脂肪源研究真鲷幼鱼的ＥＰＡ、ＤＨＡ的需求量。结果表明,饵料中缺乏ＥＰＡ、ＤＨＡ时,真鲷幼鱼生长缓慢,成活率仅达６５％,随着ＥＰＡ在饵料中的添加,幼鱼的成活率与增重率都有所增加。     

鲢鱼脂肪酸中EPA、DHA的营养新评价

通过气相色谱法对鲢鱼及其食物－－浮游生物的脂肪酸组进行分析，发现鲢鱼肌肉中二十碳五烯酸和二十二碳六烯酸的含量甚为可观，两者之和占脂肪酸总量的１９．４％￣２８．１％，鲢鱼摄食的浮游生物中富含亚麻酸、ＥＰＡ和ＤＨＡ，经过代谢转化为鲢鱼体内的ＥＰＡ和ＤＨＡ。将分析结果与海水鱼比较，在含量上也是相当的，因此，可进一步证明鲢鱼具有良好的营养价值，是非常值得的加工利用的淡水鱼类资源。     

鱼肥添加剂对硅藻和金藻生长的影响

ω３系的二十碳五烯酸（ＥＰＡ）和二十二碳六烯酸（ＤＨＡ）,对于鱼类等水产动物具有促生长作用。水体中原始生产者一藻类,尤其是硅藻、金藻、甲藻、隐藻等ＥＰＡ和ＤＨＡ含量较高且易被滤食性鱼类消化的藻类是水产动物体内ＥＰＡ、ＤＨＡ的最终来源。脂肪作为藻类代谢产物其脂肪酸组成在一定程度上受到水体环境的影响,因此,改变藻类生长环境,促进水体中藻类优势种群的变迁及藻细胞同化产物组成的改变,可以在一定范围内影响水体中藻类种群的脂肪酸组成,并最终影响到鱼类等水产动物的脂肪酸组成。本实验通过改变鱼用肥添加剂的成分及…     

海星中脂肪酸的GC-MS分析

用索氏提取器提取了海星中的脂肪,经皂化、甲酯化处理,用气相色谱-质谱法(GC-MS)鉴定了20种成分及其相对含量.海星中脂肪酸主要包括油酸(14.37%)、亚油酸(12.52%)、硬脂炔酸(7.14%)、11-廿碳烯酸(7.86%)、棕榈油酸(3.31%)、软脂酸(19.55%)、硬脂酸(8.48%)、花生酸(6.00%)和十五碳烷酸(9.01%)等;其中,不饱和脂肪酸占45.15%,饱和脂肪酸占54.85%.     

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.