太平洋牡蛎微卫星引物对三角帆蚌的适用性研究

三角帆蚌（Hyriopsis cumingii）是我国特有种,它形成的珍珠具有珠质光滑细腻、色泽鲜艳等方面的优点,是淡水蚌中育珠质量最佳者,已成为最主要的淡水养殖珍珠蚌。本研究选取已发表的32对太平洋牡蛎的微卫星引物在三角帆蚌基因组DNA中进行PCR扩增,探讨太平洋牡蛎的引物用于三角帆蚌基因组微卫星分析的可能性。通过优化PCR反应条件,筛选13对引物可在三角帆蚌基因组中扩增出特异性条带（占总数的4l％）;其中10对引物（占总数的3l％）在洞庭湖三角帆蚌小群体中即检测到了个体间等位基因的多态性,共出现40条多态性条带。10个位点杂合度大小在0．125到0．693之间,其中7个微卫星位点（Cgi-10,Cgi-22,Cgi-24,Cgi-26。Cgi-29,Cgi-30,Cgi-32）为高度多态性位点,杂合度大于0．500,而其余3个微卫星位点（Cgi-1,Cgi-18 and Cgi-25）杂合度小于0．500,为低度多态性位点。初步的结果表明,部分太平洋牡蛎的微卫星引物可以用于三角帆蚌基因组的分析,这为其它贝类微卫星标记的开发奠定了基础。     

鲮微卫星引物的鉴定及其适用性检验

利用4种鲤科鱼类的14对微卫星引物对西江流域一批野生鲮进行PCR扩增。将各扩增条带进行克隆测序,发现引物MFW1、MFW2、MFW15、MFW17、Cc7、Cc11、Bgon22扩增出的产物含有微卫星重复序列。进一步对鲮的微卫星位点MFW1、MFW2、Cc7重新设计引物,并将其分别命名为Cm1、Cm2、Cm3,新引物对鲮的扩增特异性增强。采用引物Cm1、Cm2、Cm3、Cc11、MFW15、MFW17、Bgon22对西江流域一批野生鲮进行引物适用性检验。结果表明,除引物MFW15、Cc11无多态性外,其余5对引物(Cm1、Cm2、Cm3、MFW17、Bgon22)在取样群体中扩增图谱带型丰富,随引物不同,各标记在群体中检测到的等位基因数为2到16个。各微卫星座位的期望杂合度(He)及观察杂合度(Ho)范围分别为0~0.9038和0~1,平均分别为0.6881(0.1819SD)和0.7772(0.1931SD)。座位连锁分析显示Cm1与Bgon22之间存在显著性水平连锁关系(P<0.05),其余各座位之间未检测到明显的连锁关系(P>0.05)。研究群体的遗传多样性指数平均为0.6823,多态性水平相对较高。以上结果表明,筛选获得的7个微卫星座位适于对鲮进行遗传多样性分析。     

不同温度下大西洋鳕（Gadus morhua）个体发生早期胚胎生长和卵黄蛋白的利用

本文报道了自受精至孵化,不同培育温度（０－６．１℃）大西洋鳕胚胎生长和卵黄及卵蛋白吸收动态。     

太平洋鳕(Gadus macrocephalus Tilesius)仔鱼发育过程

采用显微观察、拍照、测量的方法,对太平洋鳕(Gadus macrocephalus Tilesius)人工培育苗种各阶段仔鱼的发育(0-80 dph day post hatching)进行了研究.结果显示,在水温为2-12℃、盐度为28-32、pH为7.8-8.2、光照为800-1200 Ix、微充气静水的培育条件下,太平洋鳕早期仔鱼发育主要特征为:0-5 dph仔鱼完全营内源性营养,1 dph仔鱼黑色素沉积较初孵仔鱼颜色加深,眼球出现彩虹色素,5 dph仔鱼消化道已打通(除肝脏外);6dph仔鱼开口摄食,消化道内有小颗粒物质,营混合性营养;9dph大部分仔鱼卵黄囊吸收完毕,消化道内充满褶皱臂尾轮虫(Brachionus plicatilis),进入外源性营养期,血细胞流动清晰可见;12dph仔鱼头部黄色色素带明显;15dph仔鱼黑色素和黄色素密集,鳔器官开始形成;17dph仔鱼开始出现彩虹色素;20 dph仔鱼眼球发育完善,腹动脉可观察到明显的血流,鱼体尾部色素点开始出现;30-50 dph仔鱼各鳍条雏形发育;30 dph仔鱼尾鳍鳍条开始发育;40dph仔鱼开始摄食卤虫(Artemia sp.),第1、2、3背鳍已出现雏形;50dph仔鱼尾椎骨开始上翘,臀鳍、背鳍雏形已清晰可见;60-80 dph仔鱼色素细胞迸一步发育,各鳍条逐步发育完善,胆囊清晰可见;60 dph仔鱼鳃部呈现红色;70dph仔鱼腹部有银白色鳞片雏形出现;80dph仔鱼鳃盖已基本发育完善,腹鳍出现.本研究对太平洋鳕仔稚鱼发育过程进行了描述,可为后续规模化人工繁育的开展提供基础数据.     

太平洋鳕IRF3 基因的克隆及绝对定量表达分析

本研究通过克隆首次得到太平洋鳕(Gadus macrocephalus)干扰素调节因子3(interferon regulatory factor 3,IRF3)的部分序列。该序列长1878 bp,包含长1377 bp的完整开放阅读框(open reading frame,ORF),编码459个氨基酸,其编码的蛋白质分子量约为51 k D。经氨基酸序列比对发现,太平洋鳕IRF3的氨基酸序列包括1个含有5个保守色氨酸残基的DNA结合域(DNA binding domain,DBD)和1个保守的C端IRF关联域(IRF association domain,IAD);系统进化树分析表明,太平洋鳕IRF3与其他物种的IRF3亲缘关系较近。应用绝对荧光定量PCR方法对IRF3在不同组织和不同日龄(days post-hatching,dph)仔鱼的表达水平进行检测,并对干扰素在仔鱼期的免疫作用进行分析。组织表达绝对定量结果显示,性腺,肝和胸腺表达量高于其他组织。不同日龄仔鱼IRF3表达量结果显示,IRF3在受精卵就已经表达,在25 dph表达量大幅提高。本研究的结果为进一步研究太平洋鳕干扰素作用机制以及其在早期发育中的作用奠定了基础。     

急性温度胁迫对太平洋鳕仔稚鱼成活率、生理生化指标的影响

为探究温度胁迫对太平洋鳕的影响,以太平洋鳕仔稚鱼为研究对象,研究了温度胁迫对太平洋鳕仔稚鱼的成活率、总超氧化物歧化酶、过氧化氢酶、丙二醛的活性的影响。试验结果表明,培育温度8℃组(对照组)成活率最高(99%),15℃组的成活率最低(43.3±10.3)%,差异显著(P0.05)。2、5、11、15℃胁迫组的总超氧化物歧化酶活性在24h后急剧升高,与8℃组差异显著(P0.05)。72h后各组总超氧化物歧化酶活性开始下降,与8℃组差异不显著(P0.05)。各胁迫组的过氧化氢酶活性在48h时开始显著升高(P0.05),表明过氧化氢酶活性的变化较总超氧化物歧化酶相比具有滞后性。丙二醛活性在胁迫24h时升高(P0.05),但在48h时略有回落,72h时表现出最大的活性。     

太平洋鳕(Gadus macrocephalus)亲鱼驯化培育与早期发育特征

采捕山东威海外海黄海海域的太平洋鳕(Gadus macrocephalus)亲鱼进行驯化和培育,在人工条件下成功驯化存活野生亲鱼49尾,经短期促熟培育后,通过人工授精方式获得了多批次受精卵.对胚胎和早期仔鱼发育过程进行了观察,详细描述了从受精卵到早期仔鱼各发育时期的形态特征.结果显示,太平洋鳕成熟卵子为沉性卵,圆球形,卵径为0.9-1.1 mm,无油球.胚胎发育分为5个时期,分别为卵裂期、囊胚期、原肠胚期、神经胚期和器官形成期.在水温为9-10℃、盐度为27-29的海水中孵化,受精卵历时312 h 30 min孵化出膜.初孵仔鱼全长为(3.85±0.12) mm,6日龄仔鱼开口,肛门与外界相通,进入混合营养期.8日龄仔鱼卵黄囊消耗殆尽,开始进入外源性营养阶段.仔鱼开口饵料为轮虫(Rotifer),12日龄开始摄食卤虫(Artemia saline)无节幼体.6日龄仔鱼鳔原基形成,16日龄鳔充气成为亮泡状.12日龄仔鱼形成肠道第1个生理弯曲,22日龄仔鱼第2个肠道生理弯曲形成.研究结果可为太平洋鳕亲鱼驯化培育和苗种培育提供基础资料.     

福建漳浦太平洋牡蛎微卫星等位基因比较

本文采用Ucdcg153、157、202微卫星分子标记对福建漳浦从广东饶平引人的太平洋牡蛎育苗亲贝进行等位基因比较.两组样品(Cg♀和cg♂)携带的等位基因在微卫星重复区间及其附近存在高度相似的变异特征.这些特征区间分别是:Ucdcg153 23～40位碱基区间,Ucdcg157 73～100位碱基区间,Ucd-cg2...     

Characterization of Acid-Soluble Collagen From Bone of Pacific Cod (Gadus macrocephalus)

Acid-soluble collagen (ASC) was isolated from Pacific cod (Gadus macrocephalus) bone. The ASC was rich in glycine. The amount of imino acid was lower than that of calf skin collagen, as was the transition temperature (48.6°C). Electrophoresis revealed two different α chains (α₁ and α₂), β-component, and γ-component. Fourier transform infrared spectroscopy measurement showed that ASC was in triple-helix structure. ASC had a solubility greater than 90% in a very acidic pH range (pH 1–4), and the solubility decreased with increasing NaCl concentrations up to 3%. Lyophilized ASC had a network ultrastructure with lace-like fibers, similar to calf skin collagen sponge.     

Preliminary Observations on Spoilage Potential of Flora from Desalted Cod (Gadus morhua)

Abstract

Desalted cod products are already marketed, although still presenting some problems. Fresh raw materials and good manufacturing practices during salting, drying and desalting are essential to improve their quality and shelf life. The production of off-odor, hydrogen sulfide, trimethylamine, ornithine, putrescine, cadaverine, histamine, indole, hydrolyzed gelatin and ammonia was investigated in 127 bacterial strains isolated from dried/wet salted cod, later desalted either at 4 or 24°C. Desalting could either introduce or recover off-odor, sulfide hydrogen and/or ornithine producing strains. Cod desalting at 4°C is of great importance in order to improve the shelf life and safety of cod desalted products.     

Quality Changes During Salt-Curing of Cod (Gadus morhua) at Different Temperatures

ABSTRACT

The main aim of this study was to assess the quality changes and their causes during cod salt-curing for up to 76 days at different temperatures and a relative humidity below 80%. Salt-curing made the fish more yellow (L*a*b* scale), a color change that is more easily detected in sensory analysis against a cream color scale. Intense proteolytic breakdown took place at 12 and 18°C, leading to a greater proteolysis degree and a higher pH. A red surface discoloration of the flesh was apparent after 76 days at 18°C due to the high number of red-halophilic bacteria. These bacteria were also responsible for the highest intensity of “off”-odors and mucus obtained under these conditions. Cod salt-curing should be done below 12°C to reduce the spoilage activity of halophilic bacteria and is best done at chill temperature (close to 6°C) to obtain a good quality product.     

Occurrence of Francisella piscicida in farmed and wild Atlantic cod, Gadus morhua L., in Norway

Francisellosis, caused by the bacterium Francisella piscicida , has become one of the most serious diseases in Atlantic cod production in Norway. The major aim of this study was to determine the distribution of F. piscicida in farmed and wild fish in areas with cod farming along the Norwegian coast, and its occurrence in cod from areas without cod farming. Two real-time PCR assays, targeting the 16S rRNA gene and the FopA gene of F. piscicida , were developed since sensitive and specific diagnostic tools are required for detecting asymptomatic carriers of the bacterium. A total of 422 wild cod from 13 sampling areas and 955 farmed cod from 10 areas along the coast of Norway were examined. Using the real-time polymerase chain reaction (PCR) assays, F. piscicida was detected in wild populations of cod from all counties examined south of Sogn og Fjordane in southern Norway (overall prevalence 13%, n  = 221). Wild cod north of Sogn og Fjordane were negative for the bacterium ( n  = 201). Farmed cod from most parts of Norway were F. piscicida positive. The apparent absence of the bacterium in wild populations of cod in the northern parts of Norway and its widespread occurrence in wild cod from southern parts of Norway is believed to relate to differences in seawater temperatures.     

Technological solutions and operational measures to prevent escapes of Atlantic cod (Gadus morhua) from sea cages

Escapes of cod (Gadus morhua) from sea cages represent an economic problem for farmers and a potential environmental problem. We estimate that 0–6% of cod held in sea‐cage farms in Norway were reported to have escaped each year from 2000 to 2005, which is a high proportion compared with salmon. We interviewed employees at 19 coastal sea‐cage cod farms in Norway to investigate both how and why cultured cod escape and to document cage handling and management strategies that were effective in minimizing escapes. Based on the interviews, we describe five working hypotheses that may explain why a greater proportion of cod than salmon escape: (1) cod are more willing to escape than salmon; (2) cod bite the net cage and create wear and tear; (3) net cages have insufficient technical standards for cod culture; (4) cod are placed in sea cages at considerably smaller sizes than salmon; and (5) cod are more popular feed for predators. Preliminary testing of the hypothesis that cod bite netting and create holes was done by placing pre‐damaged net panels with cut twines and control panels inside sea cages. Holes in the pre‐damaged net panels increased in size over a period of 3 months. The type of damage indicated that biting of netting twines was the likely cause.