大瓶螺的加工技术

大瓶螺(Ampullaria gigas)又名南美螺、苹果螺、苹果蜗牛,台湾地区又称福寿螺、雪螺、金宝螺。该螺原产南美洲亚马逊河流域,在分类学上属软体动物门,中腹足目,瓶螺科,瓶螺属。这种螺具有生长繁殖快、食性杂、抗逆性强、易于养殖且成本低、肉味鲜美等优点,是一种大型优质,经济效益好的淡水养殖螺类。该螺在广东、广西等地野生分布量大。大瓶螺有冰冻螺肉、盐渍螺肉、无盐干制和含盐干制等4种主要的加工方法,加工出口和内地销售大瓶螺肉有利于我国大瓶螺资源的利用和养殖业的发展。     

盐渍大瓶螺肉的加工工艺及要点

大瓶螺(Ampullaria gigas)又名南美螺、苹果螺、苹果蜗牛,台湾又称福寿螺、雪螺。该螺原产南美洲亚马逊河流域,在分类学上属软体动物门、中腹足目、瓶螺科、瓶螺属。这种螺具有生长繁殖块、食性杂、抗逆性强、易于养殖且成本低、肉味鲜美等优点,是一种大型优质、经济效益好的淡水养殖螺类。在广东、广西等地分布量大。加工出口大瓶螺肉有利于我国大瓶     

大瓶螺的加工技术

大瓶螺(Ampullaria gigas)又名南美螺、福寿螺,原产南美洲亚马逊河流域,在分类学上属软体动物门,中腹足目,瓶螺科,瓶螺属。这种螺具有生长繁殖快、食性杂、抗逆性强、易于养殖且成本低、肉味鲜美等优点,是一种大型优质,经济效益好的淡水养殖螺类。该螺在广东、广西等地野生分布量大。大瓶螺有冰冻螺肉、盐渍螺肉、无盐干制和含盐干制等4种主要的加工方法,加工出口和内地销售大瓶螺肉有利于我国大瓶螺资源的利用和养殖业的发展。一、大瓶螺的加工工艺流程二、大瓶螺加工操作要点及注意事项1、鲜螺的采集及保存生产加工季节以4月～5月和8月～…     

人工养殖大瓶螺技术要点

大瓶螺Ａｍｐｕｌｌａｒｉａｇｉｇａｓ又名南美螺、苹果螺、苹果蜗牛，台湾又称福寿螺、雪螺。该螺原产南美洲亚马逊河流域，在分类学上属软体动物门，中腹足目，瓶螺科，瓶螺属。这种螺具有生长繁殖快、食性杂、抗逆性强、易于养殖且成本低、肉味鲜美等优点。１９８１年广东中山县从台湾引进，现已成为我国的一种大型优质、经济效益好的淡水养殖螺类。大瓶螺不仅可以人工单养，而且可以稻螺套养、稻后放养，且不影响水稻的产量。笔者从事多年的大瓶螺养殖加工，养殖的大瓶螺亩产量１０００～３０００公斤，经济收入２０００～６０００…     

出口大瓶螺肉干营养成分的研究

大瓶螺（ Ampullaria gigas Spix）又名南美螺、苹果螺、苹果蜗牛，台湾又称福寿螺、雪螺。该螺原产南美洲亚马逊河流域，在分类学上属软体动物门，中腹足目，瓶螺科，瓶螺属。这种螺具有生长繁殖块、食性杂、抗逆性强、易于养殖且成本低、肉味鲜美等优点。广东中山县自 1981年从台湾引进，已成为我国的一种大型优质，经济效益好的淡水养殖螺类。目前，除重庆牧丰养殖加工有限公司加工大瓶螺肉干出口外，还没有其他厂家加工大瓶螺肉干出口，也未见出口品级大瓶螺肉干的营养成分研究报道。为此，笔者对大瓶螺肉干的营养成分作了较全面的分析…     

大瓶螺人工养殖技术

大瓶螺 (Ampullaria gigas)又名南美螺、苹果螺、苹果蜗牛，台湾又称福寿螺、雪螺。该螺原产南美洲亚马逊河流域，在分类学上属软体动物门，中腹足目，瓶螺科，瓶螺属。这种螺具有生长繁殖块、食性杂、抗逆性强、易于养殖且成本低、肉味鲜美等优点。 1981年广东中山县从台湾引进，现已成为我国的一种大型优质、经济效益好的淡水养殖螺类。大瓶螺不仅可以人工单养，而且可以稻螺套养、稻后放养，且不影响水稻的产量。笔者从事多年的大瓶螺养殖加工，养殖的大瓶螺每 667米 2产量 1 000～ 3 000千克，经济收入 2 000～ 6 000元 /667米 2。 1水…     

卵萝卜螺──亲鳖的优质饵料

卵萝卜螺──亲鳖的优质饵料卵萝卜螺为椎实螺科萝卜螺属螺类。贝壳薄、卵圆形、左旋、无厣，螺旋部短小而尖锐，高度明显小于亮口高度，体螺层膨大呈梯形排列，壳口大，轴缘宽，轴部弯曲。本螺是非常普通的螺类，广泛分布在各种水域中。因为其壳薄适口性好，钙质丰富，有...     

大瓶螺的休眠越冬机制及越冬方法（一）

大瓶螺(Ampullaria gigas)，又名福寿螺、苹果螺、金宝螺、南美螺，在动物分类学上属软体动物门腹足纲(前鳃亚纲)中腹足目瓶螺科瓶螺属，是一种大型的淡水食用螺类，原产于热带南美洲亚马逊河流域。该螺肉质鲜嫩、营养丰富、深受人们的喜爱。因此发展大瓶螺养殖，对改善人们的食品结构以及解决鱼虾和河蟹等名特优水产品类的动物性蛋白饵料，作为无公害无污染的食品走入市场，具有重要价值。在台湾、广东等省区，冬季水温较高，大瓶螺往往过度繁殖，侵害水生作物，有人因此提出应控制养殖，限制了大瓶螺在湖南等省的养殖研究。根据笔者多年…     

织纹螺及其毒性

织纹螺,俗称麦螺、白螺、割香螺、海丝螺或者甲锥螺,属软体动物肉食螺类,成熟个体的体长一般在1cm~2cm左右,大型织纹螺体长有时可以达到3cm以上。织纹螺贝壳呈长卵圆形或尖圆锥形,螺层约5层~8层,各螺层上常有纵肋条,在体螺层的纵肋之间具有细的横肋纹形成布纹状。     

螺迪在杀螺上的应用

一、螺类生活史腹足纲通称螺类,螺生活史分为卵、幼螺和成螺三个阶段。年生2～3代,世代重叠,以成螺和幼螺越冬。越冬后的成螺于4月中旬开始交配产卵,越冬后的幼螺开春后开始生长发育到成熟后,也陆续开始交配产卵,雌螺不在水中产卵,产卵时爬到离水面15厘米以上的池边干燥处,如茎秆、沟壁、墙壁、田埂、杂草等附着物以及水生植物的茎叶上产下卵块,并粘附其上,产卵活动常在晚上进行。每只雌螺可产卵多次,一只成熟的雌螺,一般每隔5～10天产一次卵块,卵块为粉红色,每次产卵时间     

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.