Genetic evidence against panmixia in the European eel

The panmixia hypothesis--that all European eel (Anguilla anguilla) migrate to the Sargasso Sea for reproduction and comprise a single, randomly mating population--is widely accepted. If true, then this peculiar life history strategy would directly impact the population genetics of this species, and eels from European and north African rivers should belong to the same breeding population through the random dispersal of larvae. To date, the panmixia hypothesis has remained unchallenged: genetic studies realized on eel's mitochondrial DNA failed to detect any genetic structure; and a similar lack of structure was found using allozymes, with the exception of clinal variation imposed by selection. Here we have used highly polymorphic genetic markers that provide better resolution to investigate genetic structure in European eel. Analysis of seven microsatellite loci among 13 samples from the north Atlantic, the Baltic Sea and the Mediterranean Sea basins reveals that there is global genetic differentiation. Moreover, pairwise Cavalli-Sforza and Edwards chord distances correlate significantly with coastal geographical distance. This pattern of genetic structure implies non-random mating and restricted gene flow among eels from different sampled locations, which therefore refute the hypothesis of panmixia. Consequently, the reproductive biology of European eel must be reconsidered.     

基于16S rDNA序列和RFLP分析的病鳗分离菌株鉴定

结合16S rDNA基因序列和限制性片段长度多态性(RFLP)的分析方法,通过与GenBank库中已递交的细菌16S rDNA基因序列进行同源性比较,对分离自发病鳗鲡(欧洲鳗鲡,日本鳗鲡和美洲鳗鲡)的30株细菌进行初步鉴定和分类.结果表明,这些细菌可大致分为气单胞菌属(Aeromonas sp.)、假单胞菌属(Pseudomonas sp.)、邻单胞菌属(Plesiomonas sp.)、克雷伯氏菌属(Klebsiella sp.)、柠檬酸杆菌属(Citrobacter sp.)、不动杆菌属(Acinetobacter sp.)和肠杆菌属(Enterobacter sp.)等7个菌属.分析认为,部分分离菌株可能是引起鳗鲡病害的疑似致病性菌株.     

鳗鲡肝肾病病原菌的研究

从汕头地区3个养鳗场患肝肾病鳗鲡的肝脏和肾脏分离出60个菌株,用这些菌株人工感染鳗鲡能出现相同的症状,并能从肝脏或肾脏重新分离出相同的菌株,证实为该病的病原菌.这些菌株的形状基本一致,经鉴定为野生型迟呆爱德华菌(Edwardsiella tarda.wild type).这些菌株虽然是革兰氏阴性肠杆菌,但全部菌株对多粘菌素 E 高度耐药,对青霉素 G 反而较敏感.所有菌株对目前养鳗场常用的四环类抗生素及磺胺类药物高度耐药,其耐药率均达到100%,但对大多数被测试的抗菌药物敏感.     

鳝鱼静水无土养殖新技术

鳝鱼无土养殖可分为流水无土养殖和静水无土养殖两种类型。本文主要从鳝池的设计、苗种处理、日常管理等方面探讨了鳝鱼的静水无土养殖技术。     

黄鳝的地理分布及起源的探讨

<正> 一、黄鳝Monopterus albus(zuiew)的地理分布黄鳝同黄蝉、黄(鱼旦)。又简名鳝鱼或(鱼单)鱼。山、陕亦名蛇鱼。两千多年前的山海经内就有“灌河之水其中多(鱼旦)”的记载。是我国人民习见和喜食的淡水鱼类之一。但迄今其地理分布尚无专文研究。不少文献称黄鳝分布于我国各处,或称除西北、西南外我国各处均产;但事实远非如此。据笔者研究在我国仅见于辽河下游;沿滦河向上约略过承德(海拔     

日本七鳃鳗体态变型的观测研究

为进一步揭示日本七鳃鳗由以两背鳍相分离为特征的非产卵态体型变为产卵时(含产后)两背鳍相连接的产卵态体型这一体态变型现象,选取了27项体态特征可量性状,对从日本海回归 内河的日本七鳃鳗性成熟产卵群体不同时季3种类群共116尾(♀♀55,♂♂61)标本进行了系 统测量。对每一性状均用统计处理数据按类群分雌雄进行了统计学差异显著性检验对比,从而揭示出了日本七鳃鳗溯入内河时至翌春产卵前特别是产卵活动体态变型时躯体各部位具体 的变化情形。     

鳗鱼和烤鳗中六六六,DDT残留量的气相色谱分析

本文用 HP5890气相色谱仪连电子捕获检测器,在Φ3mm×2m 涂以10%OV-17的色谱柱上分离测定了鳗鱼和烤鳗中六六六和 DDT 的残留量.12批样品的测定结果,检出率100%,六六六和 DDT 的总含量均小于0.1PPM.与文献报道的波兰、美国和意大利等某些水域的鳗鱼比较,污染程度要轻得多。     

海水和淡水养殖南美白对虾脂质分析与比较

分别取海水养殖的南美白对虾 (海养虾 )和淡水养殖的南美白对虾 (淡养虾 )的肌肉2～ 3g、肝胰腺 1 g,采用 Folch液提取脂肪 ,用气相色谱法 (GC法 )分析测定脂肪的含量和组成。结果表明 :海养虾肌肉含脂肪 3.93% ,比淡养虾肌肉含脂量 2 .79%高 ;海养虾肝胰腺含脂量 1 2 .2 3% ,略低于淡养虾的 1 2 .98%。淡养雄虾的肝胰腺脂肪含量比雌虾高 ,但其肌肉含脂率比雌虾低。在已检测出的脂肪酸中 ,不饱和脂肪酸占大多数 ,而且不饱和多烯酸的含量明显高于不饱和单烯酸 (P <0 .0 1 )。海养虾和淡养虾肌肉脂肪酸含量在 C1 4 :0 ,C1 8:2 n6,C1 8:3 n3 上有显著性差异 (P <0 .0 5) ;肝胰腺脂肪酸含量在 C1 8:2 n6,C1 8:3 n3 ,C2 0 :4n6上有显著性差异 (P <0 .0 5)。南美白对虾与中国对虾、斑节对虾 (肝 )、日本对虾 (肝 )的主要脂肪酸含量在 C1 6:0 ,C1 8:0 ,C1 8:1 n9,C1 8:2 n6,C1 8:3 n3 和 C2 0 :4n6上有较大差别。     

Raptorial jaws in the throat help moray eels swallow large prey

Most bony fishes rely on suction mechanisms to capture and transport prey. Once captured, prey are carried by water movement inside the oral cavity to a second set of jaws in the throat, the pharyngeal jaws, which manipulate the prey and assist in swallowing. Moray eels display much less effective suction-feeding abilities. Given this reduction in a feeding mechanism that is widespread and highly conserved in aquatic vertebrates, it is not known how moray eels swallow large fish and cephalopods. Here we show that the moray eel (Muraena retifera) overcomes reduced suction capacity by launching raptorial pharyngeal jaws out of its throat and into its oral cavity, where the jaws grasp the struggling prey animal and transport it back to the throat and into the oesophagus. This is the first described case of a vertebrate using a second set of jaws to both restrain and transport prey, and is the only alternative to the hydraulic prey transport reported in teleost fishes. The extreme mobility of the moray pharyngeal jaws is made possible by elongation of the muscles that control the jaws, coupled with reduction of adjacent gill-arch structures. The discovery that pharyngeal jaws can reach up from behind the skull to grasp prey in the oral jaws reveals a major innovation that may have contributed to the success of moray eels as apex predators hunting within the complex matrix of coral reefs. This alternative prey transport mode is mechanically similar to the ratcheting mechanisms used in snakes--a group of terrestrial vertebrates that share striking morphological, behavioural and ecological convergence with moray eels.     

Electronic tagging and population structure of Atlantic bluefin tuna

Electronic tags that archive or transmit stored data to satellites have advanced the mapping of habitats used by highly migratory fish in pelagic ecosystems. Here we report on the electronic tagging of 772 Atlantic bluefin tuna in the western Atlantic Ocean in an effort to identify population structure. Reporting electronic tags provided accurate location data that show the extensive migrations of individual fish (n = 330). Geoposition data delineate two populations, one using spawning grounds in the Gulf of Mexico and another from the Mediterranean Sea. Transatlantic movements of western-tagged bluefin tuna reveal site fidelity to known spawning areas in the Mediterranean Sea. Bluefin tuna that occupy western spawning grounds move to central and eastern Atlantic foraging grounds. Our results are consistent with two populations of bluefin tuna with distinct spawning areas that overlap on North Atlantic foraging grounds. Electronic tagging locations, when combined with US pelagic longline observer and logbook catch data, identify hot spots for spawning bluefin tuna in the northern slope waters of the Gulf of Mexico. Restrictions on the time and area where longlining occurs would reduce incidental catch mortalities on western spawning grounds.     

Genetic diversity in Penaeus chinensis shrimp as revealed by RAPD technique

The random amplified polymorphic DNA analysis was used to estimate genetic diversity in one successively cultivated stock and three wild stocks of Penaeus chinensis shrimp, two of which were collected from the spawning and wintering grounds in the west coast of Korean Peninsula, and one from the feeding ground in the China coast of the Yellow Sea. A random primer kit was employed to scan the genomic DNA in 20 individuals of each index stock. A total of 110 reproducible RAPD markers were obtained, 68.2 % of which showed a sound eonformability within all the individuals detected, implying that the genetic variability in P. chinensis is relatively low. The proportions of polymorphic loci among these four stocks ranged from 20% to 33.3%, while the degrees of genetic polymorphisms varied from 0.0093 to 0.0307. The genetic variability of inter-stocks was higher than that of intra-stock. The genetic diversity in different stocks differed from each other; that is, a less genetic differentiation in the spawning and wintering stocks from the west coast of Korean Peninsula was revealed and their genetic diversities were higher than that of the spawning stock in the Bohai Sea and the China coast of the Yellow Sea. As detected, the genetic diversity in the successively cultivated stock was the lowest among these four stocks. Through genetic distance analysis between a random pair of individuals, a dendrogram of the above-mentioned four stocks was constructed by unweighted pair group method with arithmetic mean. The results based on cluster analysis well fitted with the geographical distribution of P. chinensis in the Bohai and Yellow Seas.     

褪黑激素在黄鳝体内分布与生殖季节性变化

选用处于不同性腺发育阶段的黄鳝,采用放射免疫技术测定了脑、眼、小肠、肝、肾、脾、心、皮肤和肌肉等组织以及血清中褪黑激素的含量．结果表明,褪黑激素在黄鳝体内的多数组织中存在（皮肤和肌肉除外）,其含量顺序为：眼＞全脑＞血清＞肝＞小肠＞肾＞脾＞心．黄鳝脑内,以下丘脑和垂体的褪黑激素水平最高,嗅叶、视盖与小脑居中,端脑及延髓最低．黄鳝体内各组织中褪黑激素水平皆显示出生殖季节性变化     

日本鳗鲡胰蛋白酶的分离纯化及性质分析

通过硫酸铵分级盐析、DEAE-Sepharose阴离子交换柱层析、Phenyl-Sepharose疏水柱层析、Sephacryl S-200凝胶过滤柱层析等方法,从日本鳗鲡（Anguilla japonica）肝胰腺中分离纯化得到胰蛋白酶,SDS-PAGE显示其分子质量为21.5 ku。以Boc-Phe-Ser-Arg-MCA为底物,胰蛋白酶最适温度和最适pH值分别为40 ℃和8.5。动力学实验表明,Km值和kcat值分别为3.1 μmol/L和59.9 s-1。丝氨酸蛋白酶抑制剂Pefabloc SC、PMSF、benzamidine、STI等对其有特异抑制效果。底物特异性结果显示,该酶特异分解Arg和Lys残基的C端。肽质量指纹图谱获得5个片段,共76个氨基酸残基,与基因文库中的日本鳗鲡胰蛋白酶氨基酸序列完全相同。说明本研究所纯化的蛋白质为胰蛋白酶。     

青蛤生产性育苗及中间培育技术研究

经过3a实践研究,重点突破了青蛤亲贝强化培育与人工催产技术,幼虫饵料单胞藻培育技术,青蛤苗种中间培育与清涂除害技术,系统掌握生产性育苗及中间培育技术,实现了青蛤苗种的规模化生产。2003￣2005年累计培育平均壳高2 mm的稚贝74.574亿粒,经中间培育后出池商品仔贝49.842亿粒,中间培育成活率达到66.84%。生产性育苗净利润163.82万元,中间培育总利润776万元,获利15 089元/km2。     

罗源湾及九龙江口美肩鳃鳚仔、稚鱼的新记录

研究了罗源湾和九龙江口美肩锶鲥仔、稚鱼的形态特征,时空分布及其与环境的关系,美肩锶鲥不仅分布在黄海和渤海,南海和东海也有分布。仔稚鱼的主要特征:眼大、吻短、稍突出、头高、体中等延长,左右侧肩,头顶包一骨质冠,头冠左右两侧及左右眼眶上有骨嵴,前锶盖骨隅角具一强棘,以上构造都着生小刺,前鳃盖骨后缘有4枚小棘突,腹囊大,背面具黑色素点,肌节37～45(8-12 28-32),背鳍一个,延长,胸鳍大,腹鳍喉位,背、臀鳍的两支鳍骨之间有尖三角形骨片。     

中华鲟的移地养殖

中华鲟（ＡｃｉｐｅｎｓｅｒｓｉｎｅｎｓｉｓＧｒａｙ）是我国一级保护动物,主要分布在东海和黄海的大陆架水域及长江干流,偶尔进入通江湖泊和支流,福建省闽江也有分布．中华鲟是江海洄游性鱼类,每年６～８月到达长江口进行溯河洄游,９～１０月陆续到达湖北江段,并在江中滞留过冬,翌年１０～１１月到宜昌江段产卵繁殖,产后立即降河返回海洋育肥［１］．受精卵约７ｄ后孵出,仔鲟顺流而下,次年５月到达长江口,９～１０月后陆续进入海洋生长,性成熟后再溯河产卵［２］．由于长江水利枢纽工程的修建切断了中华鲟产卵洄游的通道,长…     

Cool Indonesian throughflow as a consequence of restricted surface layer flow

Approximately 10 million m3 x s(-1) of water flow from the Pacific Ocean into the Indian Ocean through the Indonesian seas. Within the Makassar Strait, the primary pathway of the flow, the Indonesian throughflow is far cooler than estimated earlier, as pointed out recently on the basis of ocean current and temperature measurements. Here we analyse ocean current and stratification data along with satellite-derived wind measurements, and find that during the boreal winter monsoon, the wind drives buoyant, low-salinity Java Sea surface water into the southern Makassar Strait, creating a northward pressure gradient in the surface layer of the strait. This surface layer 'freshwater plug' inhibits the warm surface water from the Pacific Ocean from flowing southward into the Indian Ocean, leading to a cooler Indian Ocean sea surface, which in turn may weaken the Asian monsoon. The summer wind reversal eliminates the obstructing pressure gradient, by transferring more-saline Banda Sea surface water into the southern Makassar Strait. The coupling of the southeast Asian freshwater budget to the Pacific and Indian Ocean surface temperatures by the proposed mechanism may represent an important negative feedback within the climate system.     

紫海胆人工育苗技术的改进

为了提高紫海胆人工育苗效率,于2019年5月—2020年8月,以天然紫海胆为亲本,对亲本促熟和幼体培育技术进行了改进。在亲本暂养期间足量投喂海带和牡蛎,两周后进行催产,亲本排放率达到90%,且配子受精率达到95%,孵化率达到85%。在幼体培育过程中采用超滤海水和不换水育苗,并结合少量多次的投饵方法,使八腕幼体存活率达到74.95%,最终获得了3~8 mm的稚海胆30万余个,提高了紫海胆人工育苗效率。     

七彩神仙鱼胚胎及仔鱼发育研究

对七彩神仙鱼(Symphysodon aequifasciata)胚胎及仔鱼发育进行了研究,详细描述了发育各期的形态特征和所需时间.结果显示,七彩神仙鱼受精卵为红褐色粘性卵,在(29.0±0.5)℃时,孵化所需时间为52.5h.初孵仔鱼体长(3.52±0.19)mm,体高(1.27±0.07)mm,身体透明,头部粘附在产卵基上,尾部随着水流颤动.仔鱼出膜5d后亲鱼开始"奶子",到第13d基本发育完善.     

A 6,000-year sedimentary molecular record of chemocline excursions in the Black Sea

The Black Sea is the world's largest anoxic basin; it is also a contemporary analogue of the environment in which carbonaceous shales and petroleum source beds formed. Recently, Repeta et al. reported that anoxygenic photosynthesis may be an important component of carbon cycling in the present Black Sea, owing to a shoaling of the chemocline and consequent penetration of the photic zone by anaerobic waters in the past few decades. It has been suggested that this was due to an anthropogenic decrease in freshwater input to the Black Sea, although natural causes were not ruled out. Here we report the distributions of sequestered photosynthetic pigments in eight core samples of sediments from the Black Sea ranging in age from zero to 6,200 years before the present. Our results show that photosynthetic green sulphur bacteria (Chlorobiaceae [correction of Clorobiaceae]) have been active in the Black Sea for substantial periods of time in the past. This finding indicates that the penetration of the photic zone by anaerobic waters is not a recent phenomenon, and suggests that natural causes for shoaling of the chemocline are more likely than anthropogenic ones.