Cross‐species amplification in silver carp and bighead carp with microsatellite primers of common carp

About a third of microsatellite primers designed for common carp (Cyprinus carpio) was successfully amplified in silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis). These markers, inherited in Mendelian mode, are of potential applications in cypinid genetics.     

Sixteen polymorphic microsatellites in bighead carp (Aristichthys nobilis) and cross-amplification in silver carp (Hypophthalmichthys molitrix)

A (GT)(n) enriched partial genomic library of bighead carp (Aristichthys nobilis) was constructed by employing the (fast isolation by AFLP of sequences containing repeats) FIASCO protocol. Sixteen loci exhibited polymorphism with two to seven alleles/locus (mean 3.263) in a test population and the observed heterozygosity ranging from 0.100 to 0.690 (mean 0.392). Eleven of the 16 bighead carp microsatellites were found to be also polymorphic in silver carp. These polymorphic loci should provide sufficient level of genetic diversity to evaluate population structure of bighead carp.     

Multiplex microsatellite PCR panels and their application in genetic analyses of bighead carp (Hypophthalmichthys nobilis) and silver carp (H. molitrix)

In this study, three multiplex PCR panels involving twelve microsatellite loci were developed for cross-species amplification in bighead carp (Hypophthalmichthys nobilis) and silver carp (H. molitrix). The panels were verified using population genetic analyses, and species and simulated hybrid discriminations based on the genotype data of all individuals from two populations for each species. The number of alleles (Na), the observed and expected heterozygosity (Ho and He), and the polymorphic information content (PIC) of twelve loci were ranged from 5 to 20, 0.189 to 0.956, 0.177 to 901, and 0.169 to 0.887, respectively. Overall, almost all the microsatellite loci were detected as highly polymorphic across the two species. The populations of same species showed close genetic distances and similar genetic structures. Significant genetic differentiations were only detected between populations from different species, with a higher variation between species (21.17%) compared with that between populations within species (0.18%). In the species and simulated hybrid discrimination analyses, the individuals from different species were separated distinctly, and the simulated hybrids could almost be separated with the true individuals. In brief, the results indicated the high efficiency of the microsatellite multiplex panels developed in this study, which provide a practicable tool for further genetic analyses of H. nobilis and H. molitrix.     

长江鲢、鳙个体发育过程中的表型变化

采用多元分析方法,对采自长江老江河国家级四大家鱼原种场255尾1—5龄鲢、鳙的30项形态度量数据进行了分析。聚类分析显示,鲢可明显地聚成欧氏距离相对较远的1龄组和2—5龄组,鳙也可聚成欧氏距离较远的1、2龄组与3—5龄组。判别分析显示,144尾鲢个体对所聚类的两个组别的判别准确率高达98.0%,111尾鳙个体对所聚类的两个组别的判别准确率也达90.7%。这表明,在幼体向成体的发育过程中,鲢和鳙在形态上均存在着两个具有显著差异阶段。单因素方差分析显示,鲢两个组别之间有18个参数差异极显著,4个差异显著,其中10个显著或极显著地变小,12个显著或极显著地变大。鳙两个组别间有极显著和显著差异的参数分别有14个和3个,其中极显著或显著差异变小和变大的分别有12个和5个。这表明在鲢、鳙个体发育过程中,分别有73.3%和56.7%的特征参数具有生长异速现象。因此,在根据形态鉴别物种、分析种群差异、确立种质标准和作生长退算时,均应考虑所选用特征的生长异速现象。     

中华鲟养殖池背角无齿蚌和鲢鳙鱼生态修复效果比较

2009年5月31日-6月20日在广东省大沙河水库利用微型生态系统比较不同放养密度的褶纹冠蚌(Cristaria plicata)和背角无齿蚌(Anodonta woodiana)对水体氮、磷及浮游植物的影响,探讨两种蚌在控制南亚热带水库富营养化水体藻类水华上的可行性。实验结果表明,在褶纹冠蚌和背角无齿蚌处理组中,总氮、总磷和叶绿素a浓度显著增加,而铵氮的浓度显著下降;褶纹冠蚌和背角无齿蚌导致了浮游植物群落组成结构的改变和数量的增加,实验过程中绿藻所占的比例迅速上升。两种蚌之间没有显著的差异,只是在不同的作用强度下,时间上的响应不同。综合实验结果,褶纹冠蚌和背角无齿蚌难以有效地运用于我国华南地区水库的水质改善与富营养化控制。     

First U.K. recording in the wild of the bighead carp Hypophthalmichthys nobilis

Five specimens of bighead carp Hypophthalmichthys nobilis were captured from a lake in eastern England in January 2006, their first confirmed recording in the wild in the U.K. They varied in fork lengths from 746 to 796 mm and mass from 10·0 to 13·5 kg. All the fish were age 9 years and were slow growing compared to populations elsewhere in their expanded range.     

The influence of grass carp on habitat structure and its subsequent effect on the diet of tench

Ecological studies were carried out in shallow experimental sites in the Lancaster Canal to evaluate potential interactions between grass carp and feeding habits of tench.
Grass carp, through moderate weed consumption, produced better conditions for the exploitation of benthic organisms by the benthophagous tench, because tench (>35 cm fork length) were able to search for food in the open areas created. This also enabled the fish to make use of zooplankton, mainly the large species Eurycercus lamellatus whose restricted phytophilic habitat made it vulnerable to predation. Epibenthic animals, in particular gastropods and Asellus aquaticus , suffered principally from the predation, which caused severe reduction of them in the site totally depleted of vegetation. In this site, tench utilized a diet in which red chironomids were the dominant prey group together with a large amount of fine detritus.
It is suggested that a moderate control of vegetation in temperate climates, using the grass carp as the biological agent, could be a satisfactory management technique for the improvement of aquatic habitats.     

利用17个微卫星标记分析鳙鱼的遗传多样性

选用本实验室克隆的17个鳙鱼微卫星分子标记分析四川泸州和江西鄱阳湖的两个种群鳙鱼的遗传多样性及种质特性,计算和统计了杂合度、多态信息含量（PIC）、有效等位基因数、等位基因频率、遗传距离、遗传相似系数、Hardy-Weinberg平衡偏离指数等方面内容。结果表明：选择使用17个微卫星标记,其中有4个为单态标记,13个为多态标记。江西和四川鳙鱼群体每个微卫星位点的平均等位基因数分别为3.325及3.882,平均有效等位基因数分别为3.531及2.676,多态位点百分率分别为82.4及70.5, 17个微卫星标记共有等位基因71个,多态微卫星位点的PIC在0.114~0.960之间变动,平均为0.417 ,两群体位点平均观测杂合度为0.385和0.452,平均期望杂合度为0.360和0.422,两个群体间的遗传相似系数为0.897,群体间的遗传距离为0.109。     

The bioenergetics of grass carp, Ctenopharyngodon idella (Val.): the influence of body weight, ration and dietary composition on nitrogenous excretion

Nitrogenous excretion by grass carp, Ctenopharyngodon idella (Val.), was measured in the form of ammonia and urea. Endogenous nitrogen excretion (ENE) was estimated as the daily rate of excretion by grass carp which had been starved for 2 days. ENE was scaled allometrically with body weight with weight exponents of 0.75 for ammonia, 0.63 for total nitrogen and 0.63 for the energy lost. The proportion of nitrogen attributable to urea was smaller than that attributable to ammonia and decreased from 25 to 12% as fish weight increased from 2 to over 10 g.
Linear relationships were found between daily rates of ammonia, total nitrogen and energy loss and daily rates of food intake. High carbohydrate and high lipid diets were not shown to have a protein-sparing action compared to a high protein diet. Differences in the amount of nitrogen excreted were explained by the differing nitrogen contents of the diets. Nitrogen budgets were erected and their implications discussed.     

Microsatellite genetic diversity and differentiation of native and introduced grass carp populations in three continents

Grass carp (Ctenopharyngodon idella), a freshwater species native to China, has been introduced to about 100 countries/regions and poses both biological and environmental challenges to the receiving ecosystems. In this study, we analyzed genetic variation in grass carp from three introduced river systems (Mississippi River Basin in US, Danube River in Hungary, and Tone River in Japan) as well as its native ranges (Yangtze, Pearl, and Amur Rivers) in China using 21 novel microsatellite loci. The allelic richness, observed heterozygosity, and within-population gene diversity were found to be lower in the introduced populations than in the native populations, presumably due to the small founder population size of the former. Significant genetic differentiation was found between all pairwise populations from different rivers. Both principal component analysis and Bayesian clustering analysis revealed obvious genetic distinction between the native and introduced populations. Interestingly, genetic bottlenecks were detected in the Hungarian and Japanese grass carp populations, but not in the North American population, suggesting that the Mississippi River Basin grass carp has experienced rapid population expansion with potential genetic diversification during the half-century since its introduction. Consequently, the combined forces of the founder effect, introduction history, and rapid population expansion help explaining the observed patterns of genetic diversity within and among both native and introduced populations of the grass carp.     

The effect of light stimuli on dark-adapted visual sensitivity in invasive silver carp Hypophthalmichthys molitrix and bighead carp H. nobilis

Non-physical barriers, including the use of underwater strobe lights alone or paired with sound or bubbles, are being considered as a means to prevent the upstream migration of invasive silver carp Hypophthalmichthys molitrix and bighead carp H. nobilis. To optimize potential optical deterrents, it is necessary to understand the visual sensitivity of the fishes. Dark-adapted H. molitrix and H. nobilis were found to possess broad visual sensitivity between 470 to 620 nm with peak spectral sensitivity at 540 nm for H. molitrix and 560 nm in H. nobilis. To assess the effect of a strobe light on vision, dark-adapted H. molitrix, H. nobilis and common carp Cyprinus carpio, were exposed to three different 5 s trains (100, 200, or 500 ms on–off flashes) of white light and the recovery of visual sensitivity was determined by measuring the b-wave amplitude of the electroretinogram (ERG). For all species, the longest recoveries were observed in response to the 500 ms flash trains (H. molitrix mean ± SE = 702.0 ± 89.8 s; H. nobilis 648.0 ± 116.0 s; C. carpio 480 ± 180.0 s). The results suggest that strobe lights can temporarily depress visual sensitivity, which may render optical barriers less effective.     

鲢放养和施肥对盐碱池塘围隔生态系统浮游生物群落的影响

报道了单养链（Hypophthalmichthys molitrix)和施肥对盐碱池塘围隔生态系统浮游生物群落的影响,链的放养使浮游植物丰度,叶绿素a 含量和和初组生产力增大,浮游植物小型化,生物量以小型硅藻和绿藻占优势,裸藻和金藻占有相当比重;浮游动物生物量减少,特别是枝角类的生物量无鱼围隔大于有鱼围隔,且多是较大型的种类,施肥特别是施无机肥能显著地提高浮游植物丰度和初级生产力,浮游动物生物量也增大,施有机肥围隔浮游植物和浮游动物生物量虽高于有鱼对照围隔,但其浮游植物初级生产力,叶绿素a含量,浮游生物多样性指数,P／R系数均较低,链鱼的生长最差,文中讨论了滤食性鱼类和施肥对浮游生物的影响。     

EPA plays multiple roles in regulating lipid accumulation of grass carp Ctenopharyngodon idella adipose tissue in vitro and in vivo

This study was conducted to assess the effect of eicosapentaenoic acid (20:5n‐3, EPA) on lipid accumulation in grass carp Ctenopharyngodon idella adipose tissue both in vitro and in vivo. EPA was observed to inhibit the adipocyte viability in a time and dose‐dependent manner. EPA was also found to induce reactive oxygen species accumulation in vitro. The mRNA levels of caspase 3a and caspase 3b, as well as the activity of Caspase 3 increased significantly in vitro and in vivo, whereas the value of B cell leukemia 2–Bcl‐2 associated X protein decreased significantly. Besides, the pro‐apoptotic effect was relieved by α‐tocopherol. Dietary 0.52% EPA had no apparent effect on intraperitoneal fat index. Moreover, EPA promoted the hydrolytic gene expressions in vitro and in vivo, including adipose triglyceride lipase and hormone sensitive lipase‐a. Meanwhile, the lipogenic gene expressions of liver X receptor α, sterol regulatory element binding protein‐1c and fatty‐acid synthase were down‐regulated by EPA in vitro and in vivo. However, EPA also acted to promote the marker gene expressions of adipogenesis, including peroxisome proliferator‐activated receptor γ and lipoprotein lipase in vitro and in vivo. Contents of EPA increased significantly in the treatment groups in vitro and in vivo. These results support that EPA affects multiple aspects of lipid metabolism, including hydrolysis, lipogenesis, adipogenesis and apoptosis. However, it barely functioned in decreasing the lipid accumulation of Ctenopharyngodon idella under the current culture conditions.     

Richness and diversity of helminth communities in the Japanese grenadier anchovy, Coilia nasus, during its anadromous migration in the Yangtze River, China

To determine the relationship between the species richness, diversity of helminth communities, and migration distance during upward migration from coast to freshwater, helminth communities in the anadromous fish Coilia nasus were investigated along the coast of the East China Sea, the Yangtze Estuary, and 3 localities on the Yangtze River. Six helminth species were found in 224 C. nasus . Changes in salinity usually reduced the survival time of parasites, and thus the number of helminth species and their abundance. Except for the 2 dominant helminths, the acanthocephalan Acanthosentis cheni and the nematode Contracaecum sp., mean abundance of other 4 species of helminths was rather low (<1.0) during the upward migration in the Yangtze River. Mean abundance of the 2 dominant helminths peaked in the Yangtze Estuary and showed no obvious decrease among the 3 localities on the Yangtze River. Mean species richness, Brillouin's index, and Shannon index were also highest in the estuary (1.93 ± 0.88, 0.28 ± 0.25, and 0.37 ± 0.34, respectively) and did not exhibit marked decline at the 3 localities on the Yangtze River. A significant negative correlation was not seen between the similarity and the geographical distance (R = -0.5104, P = 0.1317). The strong salinity tolerance of intestinal helminths, relatively brief stay in the Yangtze River, and large amount of feeding on small fish and shrimp when commencing spawning migration perhaps were responsible for the results.     

Effects of a filter-feeding fish [silver carp, Hypophthalmichthys molitrix (Val.)] on phyto- and zooplankton in a mesotrophic reservoir: results from an enclosure experiment

SUMMARY 1. Silver carp, Hypophthalmichthys molitrix (Val.), feeds on both phyto- and zooplankton and has been used in lake biomanipulation studies to suppress algal biomass. Because reports on the effects of silver carp on lake food webs have been contradictory, we conducted an enclosure experiment to test how a moderate biomass of the fish (10 g wet weight m⁻³) affects phytoplankton and crustacean zooplankton in a mesotrophic temperate reservoir.
2. Phytoplankton biomass <30 μm and particulate organic carbon (POC) <30 μm were significantly higher in enclosures with silver carp than in enclosures without fish, whereas Secchi depth was lower. Total copepod biomass declined strongly in both treatments during the experiment, but it was significantly higher in fish-free enclosures. Daphnid biomass was also consistently higher in enclosures without fish, although this effect was not significant. However, the presence of fish led to a fast and significant decrease in the size at maturity of Daphnia galeata Sars. Thus, the moderate biomass of silver carp had a stronger negative effect on cladoceran zooplankton than on phytoplankton.
3. Based on these results and those of previous studies, we conclude that silver carp should be used for biomanipulation only if the primary aim is to reduce nuisance blooms of large phytoplankton species (e.g. cyanobacteria) that cannot be effectively controlled by large herbivorous zooplankton. Therefore, stocking of silver carp appears to be most appropriate in tropical lakes that are highly productive and naturally lack large cladoceran zooplankton.     

The cestode Atractolytocestus huronensis (Caryophyllidea) continues to spread in Europe: new data on the helminth parasite of the common carp

The caryophyllidean tapeworm Atractolytocestus huronensis Anthony, 1958, originally described from the common carp Cyprinus carpio carpio L. from North America, has recently been introduced into Europe (UK, Hungary). In the present study, the dispersion of the tapeworm in other countries of Central Europe (Slovakia and the Czech Republic) is described, including its first observation in the common carp of the Tisa River, southeastern Slovakia. Because of the transboundary location of the river, there are possible consequences of the rapid distribution of the parasite to other regions throughout the Danube River basin. The parasite has also been found in cultured carp from fishponds in South Bohemia, from where the carp are imported to many European countries. Rapid dissemination of this cestode in Europe indicates its ability to colonise new regions, and represents another example of man-made introduction of potential pathogens of carp and other farmed fish. The morphology of the A. huronensis specimens found is compared with that of specimens from Hungary and North America as well as that of Atractolytocestus sagittatus (Kulakovskaya and Akhmerov, 1965) from the same fish host in eastern Asia.     

草鱼与鲢鱼肥胖基因克隆与序列分析

肥胖基因产物leptin是调节哺乳动物摄食、能量代谢等生命活动的重要细胞因子。 应用RT-PCR和RACE法获得了草鱼(Ctenopharyngodon idellus)和鲢鱼(Hypophthalmichthys molitrix) leptin基因的全长cDNA序列分别为1 096 bp和1 176 bp,编码173和172个氨基酸。氨基酸序列同源性分析表明,草鱼和鲢鱼的leptin序列与其它鲤科鱼类leptin的同源性较高,而与其他鱼类的leptin同源性很低,但所有鱼类的leptin均含有用于形成二硫键的高度保守的半胱氨酸。系统进化树分析显示,草鱼和鲢鱼leptin与其他鱼类leptin聚于一进化分支。应用PCR和Genome Walker方法,进一步获得了草鱼和鲢鱼leptin基因的内含子和5′侧翼区序列。结果表明,获得的草鱼和鲢鱼leptin基因长度分别为2 129 bp和2 192 bp,含有与其他脊椎动物leptin相似的基因结构（含三个外显子和两个内含子）。本研究为深入研究鱼类肥胖基因结构功能关系与鱼类抗肥胖品系定向遗传选育奠定了良好的基础。     

草鱼瘦素受体基因片段序列的克隆及其组织表达分析

根据斑马鱼、大西洋鲑和人等物种巴知的瘦素受体基因核苷酸保守区序列设计一对简并引物,通过RT-PCR法从草鱼肝胰脏中首次克隆获得草鱼瘦素受体基因的片段序列.该片段序列长713 bp,编码237个氨基酸,氨基酸序列分析表明草鱼瘦素受体基因片段氨基酸序列与其他物种的相似性在35％ -86％之间.通过邻接法(Neighbor Joining,NJ)构建系统进化树显示,鱼类的瘦素受体独立聚成一支,草鱼与金鱼、斑马鱼聚成一支,再与日本青鳉、黑点青鳉、红鳍东方鲀和大西洋鲑聚成一支.通过实时荧光定量PCR分析草鱼瘦素受体基因的组织差异表达,结果表明,草鱼瘦素受体基因在肝胰脏、肌肉、脑、心脏、脾和肠系膜脂肪组织中均有表达,其中在脾脏组织中表达量最多,显著高于其他组织(P＜0.05),其次是心脏、脑、肌肉和肠系膜脂肪组织,在肝胰脏组织中表达量最低,且显著低于其他组织(P＜0.05).     

Bat species diversity and distribution in three vegetation communities of Meru National Park, Kenya

Diversity and distribution of bats was determined in four vegetation types in and around Meru National Park, Kenya between September 2000 and February 2001. Bat‐habitat studies were based on plant species dominance, cover and farming activities. Bats were captured using standard mist nets (18 m long × 2 m high) erected on poles averaging 3 m. Vegetation was broadly grouped as Acacia or Combretum wooded grassland, or Acacia–Commiphora bushland and studied using the Braun‐Blanquet method. Analysis of floristic similarity showed five vegetation species assemblages in the three broad categories. Four hundred and ninety‐five bats representing eleven genera in seven families were recorded. These were Epomophorus labiatus, E. wahlbergi, Cardioderma cor, Lavia frons, Myotis welwitschii, Scotoecus hirundo, S. leucogaster, Pipistrellus kuhlii, Mops condylurus, Chaerephon bemmeleni, Mormopterus sp., Hipposideros caffer, H. commersoni, Nycteris arge and Rhinolophus landeri. This was the first record of N. arge, M. welwitschii, C. bemmeleni and a Mormopterus species in eastern Kenya. The Combretum community was most equitable (E = 0.51) with nine bat species records, while farming areas had only four. The low species richness and increased dominance of a few generalist species on farms may be indicative of different levels of disturbance.