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.     

Reproductive condition and occurrence of intersex in bighead carp and silver carp in the Missouri River

Little is known about the reproductive biology of the exotic bighead carp Hypophthalmichthys nobilis and silver carp Hypophthalmichthys molitrix in the Missouri River. In order to fill this gap in understanding, herein is described the reproductive condition of these Asian carps. Evidence is presented which indicates that bighead and silver carp in the Missouri River have a protracted spawning period that extends from early spring through fall and some individual bighead and silver carp are spawning multiple times during a reproductive season. Although bighead and silver carps are successfully maturing and spawning in the Missouri River some reproductive abnormalities such as intersex, atresia, and sterility were observed. Knowledge of the reproductive activity of these invasive carps may be useful to resource managers tasked with their control. Furthermore, the reproductive abnormalities observed should be considered when evaluating the environmental condition of the Missouri River relative to supporting a healthy fish fauna.     

Development of silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis) genetic maps using microsatellite and AFLP markers and a pseudo-testcross strategy

Silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis) are two of the four most important pond-cultured fish species inhabiting the major river basins of China. In the present study, genetic maps of silver carp and bighead carp were constructed using microsatellite and AFLP markers and a two-way pseudo-testcross strategy. To create the maps, 60 individuals were obtained from a cross of a single bighead carp (female) and a single silver carp (male). The silver carp map consisted of 271 markers (48 microsatellites and 223 AFLPs) that were assembled into 27 linkage groups, of which 22 contained at least four markers. The total length of the silver carp map was 952.2 cM, covering 82.8% of the estimated genome size. The bighead carp map consisted of 153 markers (27 microsatellites and 126 AFLPs) which were organized into 30 linkage groups, of which 19 contained at least four markers. The total length of the bighead carp map was 852.0 cM, covering 70.5% of the estimated genome size. Eighteen microsatellite markers were common to both maps. These maps will contribute to discovery of genes and genetic regions controlling traits in the two species of carp.     

清河水库鲢、鳙鱼种群动态研究Ⅰ.生产量的估计

本文根据Robson-Chapman公式估算了清河水库鲢、鳙可捕群体的残存率,计算了非捕捞群体的残存率和种群生产量。清河水库非捕捞群体平均年残存率约为0.25,可捕群体的平均年残存率鲢为0.32、鳙为0.38。鲢、鳙鱼种群生产量分别为141和110kg/ha,种群年P/B系数分别为1.15和1.09。鲢、鳙鱼获量仅为其生产量的33%和34%,库存生物量的36%。     

Development of microsatellite markers and their utilization in genetic diversity analysis of cultivated and wild populations of the mud carp （ Cirrhina molitorella）

Microsatellite markers have been increasingly used in genetic studies on fishery species because of their high applicability in selective breeding programs.Here we reported the development of microsatellite markers and their utilization in mud carp(Cirrhina molitorella).An (CA)15 enriched library has been constructed for mud carp,using the magnetic beads enrichment procedure.Sequence analysis of 60randomly picked positive colonies indicate that 56 (93.3%) of the colonies contain microsatellites.Microsatellite polymorphism was as-sessed using 10 mud carp individuals,and 12 microsatellite loci turned out to be polymorphic.We utilized these loci to study the genetic diversity of a wild population (WM) and a cultured population (CM) of the mud carp.A total of 109 alleles were detected with an average of 9.08 alleles per locus.The mean value of the observed heterozygosity of WM and CM was 0.6361 and 0.6417,respectively,and sig-nificant decrease of genetic diversity in CM was not observed.The genetic distance between the two populations was 0.1546 and the value of Gsr was 0.0473.This showed that there existed a slight genetic differentiation between WM and CM.     

Swimming performance of adult bighead carp Hypophthalmichthys nobilis (Richardson, 1845) and silver carp H. molitrix (Valenciennes, 1844)

Although the movement of invasive bighead carp (Hypophthalmichthys nobilis) and silver carp (H. molitrix) in the Upper Mississippi River system is dependent on their ability to swim through its numerous lock‐and‐dams, the swimming performance of adults of these species is at present unknown. Using a large (2,935‐L) mobile swim tunnel, the swimming performance of adult bighead and adult silver carp was quantified at water velocities that challenged them to exhibit either prolonged and/or burst swimming (76–244 cm/s) with fatigue times of less than 10 min. Simple log‐linear models best described the relative swim speed to fatigue relationships for both species. Under these conditions, the swimming performances of adult bighead and silver carp were similar to several species of adult fishes native to the Mississippi River system, but relatively low (<3 total body lengths per second, TL/s) compared to previously studied juveniles and sub‐adult bigheaded carps (3–15 TL/s). The decline in endurance with water velocity was three times greater in bighead carp (slope = ?2.98) than in silver carp (slope = ?1.01) and the predictive ability of the bighead model was appreciably better than the silver carp model. The differences in adult swimming performance between the two species were coincident with behavioral differences (e.g. breaching in silver carp but not in bighead carp). The swimming performance data of adult bighead and silver carp can now be used to evaluate whether their passage through manmade river structures including the gates of lock‐and‐dams in the Upper Mississippi River might be reduced.     

Native bighead carp Hypophthalmichthys nobilis and silver carp Hypophthalmichthys molitrix populations in the Pearl River are threatened by Yangtze River introductions as revealed by mitochondrial DNA

Bighead carp Hypophthalmichthys nobilis and silver carp Hypophthalmichthys molitrix have been two economically important aquaculture species in China for centuries. In the past decades, bighead and silver carp have been introduced from the Yangtze River to many river systems in China, including the Pearl River, in annual, large-scale, stocking activities to enhance wild fisheries. Nonetheless, few studies have assessed the ecological or genetic impacts of such introductions on native conspecific fish populations. An mtDNA D-loop segment of 978 bp from 213 bighead carp samples from 9 populations and a 975 bp segment from 204 silver carp samples from 10 populations were obtained to evaluate genetic diversity and population integrity. Results from a haplotype network analysis revealed that most haplotypes of the Pearl River clustered with those of Yangtze River origin and only a small proportion were distinct, suggesting that both the native Pearl River bighead and silver carp populations are currently dominated by genetic material from the Yangtze River. The genetic diversity of Pearl River populations is high in both species because of this inter-population gene flow, but the diversity of native Pearl River populations is low. To preserve the native genetic diversity, stocking of non-native fingerlings should cease immediately and native Pearl River bighead and silver carp fish farms should be established. This research demonstrates the danger to native biodiversity across China because of the substantial, ongoing stock-enhancement activities without prior genetic assessment.     

50年来长江鲢、鳙形态特征的变迁(英文)

采用多元分析方法,对采自长江中游的上世纪中期(下称早期)和本世纪初(下称当前)的121尾1龄鲢、鳙的30项形态度量性状进行了分析。依据对判别贡献最大的5个参数所建立的判别公式,对鲢、鳙早期和当前群体的平均判别准确率分别达94.2%和98.%,显示鲢或鳙的当前与早期群体间在总体上存在着显著差异。单因素方差分析显示,在早期和当前群体间,鲢有12个特征差异极显著、8个差异显著,鳙分别有8个特征差异极显著或显著。其中,鲢和鳙的6个显著或极显著变大的特征参数集中在头部,而14个鲢和10个鳙的显著或极显著变小的特征参数则主要集中在躯干部与尾部。研究表明,最近50年来长江鲢、鳙的头及头部特征有相对变大的趋势,而躯干部与尾部的许多特征参数则有相对变小的趋势,这些形态演变趋势符合人们喜食鱼头、追求高经济效益的期望。     

Comparative studies on the feeding selectivity of silver carp Hypophthalmichthys molitrix and bighead carp Aristichthys nobilis

Silver carp and bighead carp exhibited size-selection for food particles in aquarium experiments, but did not select their preferred species of plankton actively when they were distributed evenly in the water. They also possessed the capacity of selection for feeding area. The removal rates (% g⁻¹ fish weight) of silver carp for smaller plankton (phytoplankton) were higher than those of bighead carp. The removal rates by the latter for bigger plankton (zooplankton) were higher than those of silver carp, but for plankton about 70 μm dia. the rates by the two species were almost equal.     

Isolation and characterization of microsatellite markers from Fangzheng silver crucian carp,Carassius auratus gibelio (Bloch), and cross‐amplification in the closely related species crucian carp,Carassius auratus auratus (Linnaeus)

We report the development of 20 microsatellite markers for Fangzheng silver crucian carp, Carassius auratus gibelio (Bloch). Nineteen out of 20 showed polymorphism with alleles ranging from two to 14. These loci were screened to amplify the closely related species crucian carp, Carassius auratus auratus (Linnaeus) and all of them can amplify DNA with the size similar to the former. The origin of silver crucian carp is in issue and the population genetic structure is still unclear. Microsatellite markers isolated from the silver crucian carp and their utility in the crucian carp will be useful for these researches.     

Microsatellite markers in common carp (Cyprinus carpio L.)

Microsatellite markers of the poly (CA) type in common carp ( Cyprinus carpio L.) are described. Clones containing a (CA) repeat were isolated from a common carp genomic library and sequenced. The number of repeats found was high compared to mammals but comparable with other teleost fishes. Classification of the repeats (perfect, imperfect and compound) are compared with the Atlantic cod ( Gadus morhua L.), rainbow trout ( Oncorhynchus mykiss ), and Atlantic salmon ( Salmo salar L.). A total of 41 primer sets were designed and tested for polymorphism on a test panel of eight animals (derived from outbred lines, inbred lines and gynogenetic clones). Thirty-two markers were found to be polymorphic. The heterozygosity in the outbred animals was 60·4%, 51·1% in the inbred animals and 0% in the gynogenetic clones. The average number of alleles among the eight animals was 4·7 per marker. Six markers (18·8%) gave an additional polymorphic amplification product besides the polymorphic amplification product in the expected size range. The possibility that these loci are tetraploid is discussed. The polymorphic loci described for common carp will be valuable as genetic markers for use in population, breeding, and evolutionary studies.     

Molecular characterization of glutathione peroxidase gene from the liver of silver carp, bighead carp and grass carp

The cDNAs encoding glutathione peroxidase (GPx) were cloned and sequenced from the liver of three Chinese carps with different tolerance to hepatotoxic microcystins, phytoplanktivorous silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis), and herbivorous grass carp (Ctenopharyngodon idellus). Using genome walker method, a 750 bp 5'-flanking region of the silver carp GPx gene was obtained, and several potential regulatory elements were identified in the promoter region of the GPx gene. The silver carp GPx gene was widely expressed in all tissues examined. Despite phylogenetic analysis, assigning this newly described carp GPx to the group of mammalian GPx2, the carp GPx seems more similar to GPx1 from a physiological point of view. The constitutive expression pattern of the three carp liver GPx gene, shows a positive relationship with their tolerance to microcystins.     

微卫星DNA标记分析德国镜鲤的遗传潜力

结合体重、体长、体高等数量性状, 用30个微卫星分子标记, 评估了3个德国镜鲤群体的遗传潜力, 共检测到287个等位基因, 559种基因型, 片段长度109~400 bp, 有效等位基因数1.1014~6.4665, 观察杂合度0.0968~0.9892, 期望杂合度0.0926~0.8554, 位点多态信息含量0.08787~0.8559, 其中中度多态(0.25≤PIC≤0.5)13个, 高度多态(PIC≥0.5)13个。统计结果显示: 3个群体的遗传潜力处于中度水平, 双来养殖群体的遗传潜力比换新和松浦繁殖群体低。同时, 用30个基因座的不同等位基因和基因型与双来群体的体重、体长、体高进行了连锁分析, 得到2个与镜鲤体长相关的微卫星分子标记(HLJ319, HLJ693)和1个与体高相关的位点(HLJ677), 与体长相关的1个位点(HLJ693)还与体重连锁。将此遗传标记在鲤鱼重组自交系中验证, 结果显示: 主要经济性状相连锁的3个遗传标记中HLJ319与鲤鱼体长性状的QTL定位结果基本一致。     

Isolation and characterization of nine polymorphic microsatellite loci in the rock carp, Procypris rabaudi (Tchang)

Nine highly polymorphic microsatellite loci were isolated from AC- and GATA-repeat microsatellite enrichment DNA libraries in the rock carp, Procypris rabaudi (Tchang). The number of alleles for these loci ranged from eight to 18 in tested individuals. Polymorphism information content ranged from 0.712 to 0.908 with an average of 0.837. Average observed and expected heterozygosities were 0.719 and 0.870, respectively. These molecular markers will be useful for the assessment of genetic diversity and analysis of population structure in wild rock carp.     

A second‐generation genetic linkage map for bighead carp (Aristichthys nobilis) based on microsatellite markers

Bighead carp (Aristichthys nobilis) is an important aquaculture fish worldwide. Genetic linkage maps for the species were previously reported, but map resolution remained to be improved. In this study, a second‐generation genetic linkage map was constructed for bighead carp through a pseudo‐testcross strategy using interspecific hybrids between bighead carp and silver carp. Of the 754 microsatellites genotyped in two interspecific mapping families (with 77 progenies for each family), 659 markers were assigned to 24 linkage groups, which were equal to the chromosome numbers of the haploid genome. The consensus map spanned 1917.3 cM covering 92.8% of the estimated bighead carp genome with an average marker interval of 2.9 cM. The length of linkage groups ranged from 52.2 to 133.5 cM with an average of 79.9 cM. The number of markers per linkage group varied from 11 to 55 with an average of 27.5 per linkage group. Normality tests on interval distances of the map showed a non‐normal marker distribution; however, significant correlation was found between the length of linkage group and the number of markers below the 0.01 significance level (two‐tailed). The length of the female map was 1.12 times that of the male map, and the average recombination ratio of female to male was 1.10:1. Visual inspection showed that distorted markers gathered in some linkage groups and in certain regions of the male and female maps. This well‐defined genetic linkage map will provide a basic framework for further genome mapping of quantitative traits, comparative mapping and marker‐assisted breeding in bighead carp.     

Genetic diversity and differentiation of Russian common carp (Cyprinus carpio L.) breeds inferred from RAPD markers

Polymorphic components of the common carp Cyprinus carpio L. genome were examined by means of polymerase chain reaction with random primers (RAPD-PCR). Using four primers, genetic diversity estimates were obtained for 12 populations and seven strains of Russian common carp breeds, as well as for European Hungarian common carp and Amur wild common carp (N = 87). The highest number of polymorphic loci was revealed in Angelinskii common carp, as well as in the samples of Altai common carp and Amur wild common carp (P = 23.8-18.7%), while the lowest number of polymorphic loci was in the BB strain of Ropsha common carp. The index of genetic diversity, H, was high (11%) in Amur wild common carp, as well as in Altai and Angelinskii common carps. In the remaining breeds, the value of this index varied from 4 to 8%. Based on summarized RAPD profile (132 bands), a dendrogram of genetic differences was constructed. In this dendrogram, all breeds examined grouped into two clusters. One of the clusters was formed by Hungarian and Angelinskii common carps, and the three samples of Altai common carp. The second cluster was formed by the group consisting of the representatives of Cherepetskskii, Stavropol, and Ropsha common carps, along with the differing from them Amur wild common carp. The observed differentiation was confirmed by the analysis of the polymorphic markers variance by the method of principle components. Evolutionary history and the reasons for genetic differentiation of Russian common carp breeds are discussed.     

Body condition (Wr) and reproductive potential of bighead and silver carp hybrids: Postzygotic selection in the Mississippi River Basin

Invasive bighead (Hypophthalmichthys nobilis) and silver carp (H. molitrix) are reproductively isolated in their native range, but form a bimodal, multigenerational hybrid swarm within the Mississippi River Basin (MRB). Despite observed F₁ hybrid superiority in experimental settings, effects of postzygotic selection on bighead and silver carp hybrids have not been tested in a natural system. Individual parent and hybrid genotypes were resolved at 57 species‐specific loci and used to evaluate postzygotic selection for body condition (W_r) and female reproductive potential (presence of spawning stage gonads and gonadosomatic index [GSI]) in the MRB during 2009–2011. Body condition in the Marseilles Reach, Illinois River declined with a decrease in species‐specific allele frequency from 1.0 to 0.4 for each species and early generation hybrids (F₁, F₂, and first‐generation backcross) had lower mean W_r than late generation hybrids (2nd+ generation backcrosses) and parentals. Proportions of stage IV and stage V (spawning stage) female gonads differed between bighead and silver carp, but not among parentals and their early and late generation hybrids within the MRB. Mean GSI values did not differ between parentals and hybrids. Because reproductive potential did not differ between hybrids and parentals, our results suggest that early generation hybrids occur in low frequency either as a factor of poor condition (W_r) and postreproductive survival, infrequent reproductive encounters by parental bighead and silver carp, or selection pressures acting on juvenile or immature life stages. Our results suggest that a combination of genetic and environmental factors may contribute to the postzygotic success of bighead and silver carp hybrids in the Mississippi River Basin.     

Genetic diversity and differentiation of Russian common carp (Cyprinus carpio L.) breeds inferred from RAPD markers

Polymorphic components of the common carp Cyprinus carpio L. genome were examined by means of polymerase chain reaction with random primers (RAPD-PCR). Using four primers, genetic diversity estimates were obtained for 12 populations and seven strains of Russian common carp breeds, as well as for European Hungarian common carp and Amur wild common carp (N = 87). The highest number of polymorphic loci was revealed in Angelinskii common carp, as well as in the samples of Altai common carp and Amur wild common carp (P = 23.8?18.7%), while the lowest number (12.8%) of polymorphic loci was in the BB strain of Ropsha common carp. The index of genetic diversity, H, was high (11%) in Amur wild common carp, as well as in Altai and Angelinskii common carps. In the remaining breeds, the value of this index varied from 4 to 8%. Based on summarized RAPD profile (132 bands), a dendrogram of genetic differences was constructed. In this dendrogram, all breeds examined grouped into two clusters. One of the clusters was formed by Hungarian and Angelinskii common carps, and the three samples of Altai common carp. The second cluster was formed by the group consisting of the representatives of Cherepetskskii, Stavropol, and Ropsha common carps, along with the differing from them Amur wild common carp. The observed differentiation was confirmed by the analysis of the polymorphic markers variance by the method of principle components. Evolutionary history and the reasons for genetic differentiation of Russian common carp breeds are discussed.     

Comparison of the trophic niches between two planktivorous fishes in two large lakes using stable isotope analysis

This paper studied the sources of food and the trophic levels of silver and bighead carps using stable isotopes (δ¹³C and δ¹⁵N) analysis in Lake Qiandao and Lake Taihu. The δ¹³C values of POM and phytoplankton indicated that Particulate Organic Matter (POM) is of terrestrial origin in LQ and phytoplankton origin in LT. The different signature of δ¹⁵N of phytoplankton and POM also showed the different extent of anthropogenic impacts on the two lakes, with higher impacts in LT than in LQ. In LQ the trophic levels of silver and bighead carps were significantly different (2.48 ± 0.19 and 2.66 ± 0.19, respectively), while in LT the difference was not significant (2.15 ± 1.54 and 2.36 ± 0.38, respectively). Using a mixing model, we found that silver and bighead carps consumed a major proportion on phytoplankton and/or POM in both lakes with higher contribution of phytoplankton in more eutrophic lake. Silver and bighead carps had clear differentiation in food resources with silver carp more on POM and bighead more on zooplankton in deep and mesotrophic lakes. Contrary to this, both carps fed primarily on phytoplankton (and POM) and may have more niche overlaps in shallow and eutrophic lakes.