可口革囊星虫养殖试验

<正>可口革囊星虫(Phascolosoma esculenta)俗称土笋、海丁、沙虫等，隶属星虫动物门(Sipuncula)、革囊星虫纲(Phascolosomatidea)、革囊星虫科(Phascolosomatidae)、革囊星虫属(Phascolosoma)，在我国主要分布于浙江、福建、广东、广西等地^[1]。其肉质脆嫩、味道鲜美，含有丰富的蛋白质及人体所需的多种氨基酸和微量元素，具有滋阴降火、补肾益智的功效，有“海洋冬虫夏草”的美誉^[2-4]。     

可口革囊星虫人工养殖试验

可口革囊星虫（Phascolosoma esculenta)俗称海丁、沙虫，属星虫门、革囊星虫科动物，为我国的特有种，分布于浙江以南沿海，栖息于潮间带营底埋生活，体柔软蠕虫状、长圆筒形，最大个体约10cm，以底栖硅藻、有机碎屑为食。可口革囊星虫肉味鲜美、营养丰富，加工成品“沙虫干”是著名的海产珍     

可口革囊星虫的生物学特性与养殖技术

可口革囊星虫(Phascoknma esulenta)属于星虫动物门革囊星虫科革囊星虫属动物，为我国特有种，广泛分布于浙江、福建、广东、广西、海南和台湾等省区，在各产地均为著名小吃，具有滋阴、补肾、去火的食疗作用，被誉为“动物人参”。在浙江一带加工成“沙虫干”，是著名的海产珍品。在闽南地区用做传     

可口革囊星虫与贝类间养技术

可口革囊星虫(Phascolosoma esculenda)俗称海丁、海马蝗、沙虫,属星虫门、革囊星虫科动物,为我国的特有种,分布于东南沿海。该种类含有丰富的氨基酸,     

盐度对不同规格可口革囊星虫耗氧率和排氨率的影响

水温18.5~20℃下,采取实验生态学方法,测定了10、15、20、25、30和35盐度下3种规格[干质量(0.220±0.000)、(0.489±0.002)g和(0.899±0.002)g]可口革囊星虫的耗氧率和排氨率。试验结果表明,盐度、规格均显著影响可口革囊星虫的耗氧率和排氨率(P0.05)。在盐度10~25时,3种规格可口革囊星虫的耗氧率和排氨率均随盐度增加而增大,盐度25时达到峰值后,随着盐度增大而减小。耗氧率和排氨率与盐度呈一元二次函数关系:y=ax~2+bx+c。在相同盐度下,可口革囊星虫的耗氧率和排氨率随体质量的增大而显著减小(P0.05),且耗氧率和排氨率与干质量符合y=amb模型。盐度10~35时,可口革囊星虫的氧氮比值为5.947~25.246,表明可口革囊星虫主要由蛋白质和脂肪提供能量。     

可口革囊星虫高密度养殖技术

正可口革囊星虫俗称泥丁,是生长在潮间带高潮区、泥沙底质地带的经济类星虫,主要分布于我国南海沿岸海滩,红树林底下的滩涂是它的最佳栖息地。笔者对可口革囊星虫育苗及养成的探索始于2012年,现将多年累积的经验与大家分享。一、可口革囊星虫养殖场地的选址可口革囊星虫以海底的有机碎屑、底栖硅藻     

重金属镉和锌对可口革囊星虫的毒性试验

研究了镉、锌离子对可口革囊星虫的单一和联合毒性。结果显示:镉离子对可口革囊星虫的48 h和96 h半致死浓度分别为501 mg/L和175 mg/L,锌离子对可口革囊星虫的48 h和96 h半致死浓度分别为82 mg/L和61 mg/L,镉和锌对可口革囊星虫的安全浓度分别为17.5 mg/L和6.1 mg/L;镉和锌对可口革囊星虫的联合毒性在48 h和96 h时AI<0,相互拮抗作用明显。     

可口革囊星虫生态繁育技术的研究

可口革囊星虫适宜在腐殖质多、底质较硬的互花米草区域生长繁殖。开展可口革囊星虫互花米草区繁养殖,可以把互花米草有害区改造成可口革囊星虫繁养殖基地,变废为宝充分保护利用海洋环境。2018年～2020年,依托福建省水产技术推广总站科技创新与推广示范项目,笔者在福建省霞浦县埕坞互花米草蔓延滩涂进行可口革囊星虫生态繁育试验,取得了较好的效果。     

可口革囊星虫人工养殖获高效

可口革囊星虫Phascolosoma esculenta俗称海丁、沙虫,属星虫门、革囊星虫科动物,为我国的特有种,分布于浙江以南沿海,栖息于潮间带,营底埋生活,体柔软蠕虫状、长圆筒形,最大个体约10厘米,以底栖硅藻、有机碎屑为     

可口革囊星虫规模化生态繁育试验

为缓解可口革囊星虫苗种紧缺的现状,探索其批量苗种繁育技术,于2011~2013年在浙江省温岭市利用潮间带滩涂模拟自然生态建立生态繁育区,面积由110亩(15亩=1 hm~2,下同)扩大到210亩,开展了可口革囊星虫生态繁育试验。2013年,在繁育区选取20亩作为放养区,放养规格462尾/kg的亲体2 625 kg,折合放养密度6.064万尾/亩,2014年6月,对210亩生态繁育区自然繁育的星虫苗种进行测产,测得星虫苗种数量为3.375亿尾,规格为2 753尾/kg,3年累计培育可口革囊星虫苗种7.174亿尾。数据显示,可口革囊星虫的生态繁育试验收效甚佳,如能进一步扩大生态繁殖规模,将在一定程度上缓解可口革囊星虫苗种紧缺的现状。     

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.