长吻(鱼危)养殖群体与野生群体遗传多样性分析

长吻(鱼危)(Leiocassis longirostris)是中国土著珍稀鱼类。近年来, 由于江河水利工程、环境污染及人类生产活动已经对江河的渔业资源造成了难以逆转的破坏, 长吻(鱼危)的渔业资源已逐渐枯竭。目前, 长吻(鱼危)在四川、广东等地实现适度规模养殖。以四川眉山、湖北石首和安徽淮南3个人工养殖长吻(鱼危)群体及4个长江野生长吻(鱼危)群体(重庆段、武汉段、安庆段和南京段)为实验材料, 利用线粒体DNA (mtDNA)控制区序列作为分子标记对135个个体的遗传结构进行了分析。结果表明, 在790 bp 的同源序列中, 长吻(鱼危) 3个养殖种群共检测到变异位点27个, 占全部序列的3.42%, 66个个体共检测到18种单倍型; 在野生群体中, 69个个体共检测到35个变异位点和36个单倍型, 长吻(鱼危)野生群体平均单倍型多样性和平均核苷酸多样性(Hd=0.9736±0.0070, Pi=0.0087±0.0015)高于长吻(鱼危)养殖群体(Hd=0.8867±0.0013, Pi=0.0056±0.0013); 群体间的遗传分化水平较低(F_st值为0.0014—0.1125)。采用邻接法(NJ法)和统计简约原理对所有单倍型进行系统发育树和统计简约网状图的构建, 结果表明: 各群体内的个体均不能分别构成独立的分支, 而是相互交叉聚在一起。分析结果表明, 长吻(鱼危)养殖群体与野生群体之间的基因交流充分, 未出现遗传分化, 但相对长吻(鱼危)野生群体, 长吻(鱼危)养殖种群多态性偏低。     

Isolation and characterization of microsatellite loci in Pimelodus maculatus (Siluriformes: Pimelodidae)

To evaluate genetic variability in Pimelodus maculatus, a small migratory catfish common in South America, we isolated and characterized several microsatellite markers from individuals collected from a population in the River Grande (Brazil). A total of 11 loci were obtained and analyzed. All the loci were polymorphic, with the number of alleles ranging from three to 27 per locus. Observed and expected heterozygosities ranged from 0.5 to 0.89 and from 0.53 to 0.95, respectively. These polymorphic markers can be used as effective tools to study the genetic structure in populations of this species.     

A microsatellite-based genetic linkage map for channel catfish, Ictalurus punctatus

Microsatellite loci were identified in channel catfish gene sequences or random clones from a small insert genomic DNA library. Outbred populations of channel catfish contained an average of eight alleles per locus and an average heterozygosity of 0.70. A genetic linkage map of the channel catfish genome (N = 29) was constructed from two reference families. A total of 293 microsatellite loci were polymorphic in one or both families, with an average of 171 informative meioses per locus. Nineteen type I loci, 243 type II loci, and one EST were placed in 32 multipoint linkage groups covering 1958 cM. Nine more type II loci were contained in three two-point linkage groups covering 24.5 cM. Twenty-two type II loci remained unlinked. Multipoint linkage groups ranged in size from 11.9 to 110.5 cM with an average intermarker distance of 8.7 cM. Seven microsatellite loci were closely linked with the sex-determining locus. The microsatellite loci and genetic linkage map will increase the efficiency of selective breeding programs for channel catfish.     

Isolation and characterization of 12 polymorphic microsatellite markers for the frog Pelophylax hubeiensis

Twelve polymorphic microsatellite loci were isolated from an (AC)n- and (AG)n-enriched DNA library for the endemic Chinese frog Pelophylax hubeiensis (Ranidae). The number of alleles per locus ranged from two to eight, with a mean of 5.17. The observed and expected heterozygosities ranged from 0.226 to 0.839 and from 0.204 to 0.826, with means of 0.568 and 0.656, respectively. No significant linkage disequilibrium was detected among these loci. However, two significant deviations from HWE were discovered at loci Pehu-11 and Pehu-12 (P<0.05). MICRO-CHECKER tests showed that null alleles could be present at locus Pehu-12. These polymorphic microsatellite loci can be employed for exploring mating mechanisms, population genetic structure and other relevant genetic investigations of P. hubeiensis.     

Genetic variation at mtDNA and microsatellite loci in Chinese longsnout catfish (<Emphasis Type="Italic">Leiocassis longirostris</Emphasis>)

Genetic variability and population structure of the Chinese longsnout catfish Leiocassis longirostris Günther in the Yangtze River was examined with mitochondrial control region sequences and nuclear microsatellite markers. A 705-bp segment of the mitochondrial DNA control region was sequenced from 132 samples, which identified a total of 61 haplotypes. The Chinese longsnout catfish in the Yangtze River was characterized with high haplotype diversity (h = 0.9770 ± 0.0041) but low nucleotide diversity (π = 0.0081 ± 0.0043). Median-joining network analysis revealed a star-shaped pattern and mismatch distribution analysis found a smooth unimodal distribution, which suggested that this species in the Yangtze River underwent a population expansion following bottlenecks and/or they originated from a small size of founding population. It was estimated that the possible time of population expansion was 139,000–435,000 years before present, a time period in the middle Pleistocene. The analysis of molecular variance and phylogenetic reconstructions did not detect significant geographic structure between different river sections. This pattern of genetic variation was further evidenced with nuclear microsatellite markers. The genetic differentiation between above and below the Gezhouba Dam and Three Gorges Dam is very small at mitochondrial and nuclear levels, which suggested that these recently developed dams might have not significantly resulted in population genetic fragmentation in the Chinese longsnout catfish. However, the potential exacerbation of genetic structuring by the dams should not be overlooked in the future.     

Isolation and characterization of twelve novel microsatellites in yellow catfish, Pelteobagrus fulvidraco

The yellow catfish Pelteobagrus fulvidraco is a freshwater fish species. Due to overfishing and pollution of freshwater ecosystems, the wild stocks of this fish reduced substantially. We isolated and characterized 12 polymorphic microsatellites of this species. The number of alleles at the 12 microsatellite loci ranged from four to eight, with an average of 6.6/locus. The average observed heterozygosity was 0.72, whereas the expected heterozygosity ranged from 0.60 to 0.86 (average: 0.80). All 12 microsatellites conformed to Hardy–Weinberg Equilibrium and were in linkage equilibrium. These 12 novel microsatellites could facilitate studies of genetic diversity and population structure of the yellow catfish to supply necessary information of conservation of the yellow catfish.     

基于转录组测序的大熊猫多态性微卫星标记筛选

结合已公布的大熊猫Ailuropoda melanoleuca基因组和本实验室所测6只大熊猫的转录组数据,筛选多态性微卫星位点并分析其组成及特征。结果显示:共获得326个多态性微卫星位点,其中二碱基多态性微卫星最多,共228个,占69.93%;三、四、五、六碱基所占比例分别为9.51%、14.11%、5.21%、1.22%。根据分析结果中缺失率与标准差2项指标以及位点序列长度,选取20个多态性二碱基微卫星位点,用于25只大熊猫个体血液DNA进行PCR验证并做后续分析。结果表明:不同位点的等位基因数为2~8,平均等位基因数为3.70,观测杂合度、期望杂合度分别为0~1.000、0.280~0.784,平均值分别为0.472和0.532。在Bonferroni校正后,证实4个位点显著偏离哈迪-温伯格平衡,所有位点未观察到显著连锁不平衡(P>0.01)。20个位点多态信息含量(PIC)在0.246~0.734,其中具有高度多态性的位点9个(PIC>0.50),11个位点呈中度多态性(0.25相似文献   

Cloning and characterization of microsatellite loci in channel catfish, Ictalurus punctatus

Short tandem repeat (microsatellite) loci were cloned from the channel catfish, Ictalurus punctatus , genome for use as molecular markers for genetic improvement of this important agricultural species. Plasmid clones containing catfish genomic DNA inserts were identified, by hybridization with tandem repeat DNA probes, and sequenced using automated laser fluorescence. A feral population of catfish displayed levels of heterozygosity greater than 0·7 for 13 of 22 loci and heterozygosity greater than 0·5 for 20 of 22 loci. Allelic polymorphism ranged from three to 17 alleles per locus in the feral population. Populations of domestic, farm-raised catfish and a research strain displayed levels of heterozygosity similar to the feral population. Non-invasive tissue sampling provided abundant material for the polymerase chain reaction-based genotype assay. The microsatellite loci will be useful in the molecular characterization and genetic improvement of channel catfish populations.     

Genetic variation and phylogenetic relationship between two species of yellow catfish, <Emphasis Type="Italic">Horabagrus brachysoma</Emphasis> and <Emphasis Type="Italic">H. nigricollaris</Emphasis> (Teleostei: Horabagridae) based on RAPD and microsatellite markers

The two species of yellow catfish, Horabagrus brachysoma and H. nigricollaris are categorized as ‘endangered’ and ‘critically endangered’ respectively in their wild habitat. Proper knowledge of genetic structure and variability of these endangered species are highly essential for the management, conservation and improvement of fish stocks. Therefore, genetic variation and phylogenetic relationships between these species of yellow catfish sampled from Chalakkudy River in the hot spot of biodiversity-Western Ghats region, Kerala, India were analyzed by using Random amplified polymorphic DNA (RAPD) and microsatellite markers. 85 RAPD and five microsatellites loci were detected to analyze the genetic variation and phylogenetic relationships among these species. Out of 85 RAPD loci produced only 52.94% were polymorphic whereas in microsatellite, all 5 loci were polymorphic (100%). Species-specific RAPD bands were found in both species studied. In microsatellite, the number of alleles across the five loci ranged from 1 to 8. The observed heterozygosities in H. brachysoma and H. nigricollaris were 0.463 and 0.443, respectively. Here, both RAPD and microsatellite methods reported a low degree of gene diversity and lack of genetic heterogeneity in both species of Horabagrus which strongly emphasize the need of fishery management, conservation and rehabilitation of these species.     

Development and characterization of genic SSR markers from low depth genome sequence of <Emphasis Type="Italic">Clarias batrachus</Emphasis> (magur)

Indian magur (Clarias batrachus) is an important freshwater catfish, which is listed as endangered under A3cde + 4acde ver. 3.1 categories by the IUCN (2015) due to decreasing population trend. Microsatellites or short sequence repeats (SSRs) tagged to genes have been utilized as gene marker. In the present study, 31,814 SSRs of C. batrachus (magur) were identified using microsatellite identification tool programme from the next generation sequencing data generated on Roche 454 and Ion Torrent platforms. A bioinformatics pipeline, with stringent criteria resulted in selection of 1672 microsatellite loci falling in the genic region. Initially, a total of 30 loci were selected for primer development; and of these 14 were successfully amplified and five were found to be polymorphic in 30 individuals of C. batrachus (magur). The observed as well as expected heterozygosity ranged from 0.038 to 0.526 and 0.434 to 0.784, respectively, and the number of observed alleles ranged from three to five. The study reported the application of next generation sequencing technologies for rapid development of microsatellite loci in Indian catfish species, C. batrachus (magur).     

Isolation and characterization of microsatellites in the Asian walking catfish Clarias macrocephalus

Microsatellite loci were characterized in the walking catfish, Clarias macrocephalus, random clones from a small genomic library using a (GT)₁₅ probe. Primers for DNA amplifications using polymerase chain reaction (PCR) were designed and synthesized for 23 loci. Twelve loci were polymorphic, with the number of alleles ranging from two to 13 alleles per locus. Developed microsatellite primers should prove useful for population studies and genetic mapping of the walking catfish.     

Isolation and characterization of microsatellites in Chinese soft‐shelled turtle,Pelodiscus sinensis

Fifteen polymorphic microsatellite loci were developed for the Chinese soft‐shelled turtle (Pelodiscus sinensis) from the (GT)_n microsatellite‐enriched genomic library, using the fast isolation by amplified fragment length polymorphism of sequences containing repeats protocol. The polymorphism of all 15 loci ranged from two to seven alleles with observed heterozygosities ranging from 0.03 to 0.98 (mean 0.43) in one population of 40 individuals. These novel loci will be helpful for understanding the population structure at genetic level and marker‐assisted breeding of this vulnerable species.     

Polymorphic microsatellite loci in the Chinese pond turtle (Chinemys reevesii)

Eight novel polymorphic microsatellite loci developed from a microsatellite enriched genomic library, are presented for the Chinese pond turtle (Chinemys reevesii). We screened 30 individuals from three populations and detected high levels of polymorphism for all eight loci with the number of alleles/locus ranging from 7 to 17 (average = 10.88). The values of expected and observed heterozygosities ranged from 0.703 to 0.920 and 0.321 to 0.966, respectively. These highly variable loci will provide a powerful molecular toolkit for studies of population structure, gene flow, and paternity assignment.     

Isolation and characterization of microsatellite markers in the newly discovered invasive fruit fly pest in Africa, Bactrocera invadens (Diptera: Tephritidae)

We describe the isolation and characterization of 11 polymorphic microsatellite loci from the recently discovered fruit fly pest, Bactrocera invadens. The polymorphism of these loci was tested in individual flies from two natural populations (Sri Lanka and Democratic Republic of Congo). Allele number per locus ranged from three to 15 and eight loci displayed a polymorphic information content greater than 0.5. These microsatellite loci provide useful markers for studies of population dynamics and invasion history of this pest species.     

Isolation and characterization of 15 polymorphic microsatellite DNA loci from Argyrosomus japonicus (mulloway), a new aquaculture species in Australia

Fifteen microsatellite loci were isolated for population genetic studies of mulloway (Argyrosomus japonicus), a commercial/recreational fish species in Southern Australia. A genomic library was screened randomly for di- tri- and tetranucleotide repeats. Fifteen microsatellite marker loci were developed that were highly polymorphic (allele number ranged from four to 18). Observed and expected heterozygosities ranged from 0.17 to 1 and from 0.27 to 0.91, respectively. These markers have proven useful for estimating genetic variation and for evaluating population structure across the species' natural distribution. They also provide powerful tools for optimizing hatchery practices to conserve genetic diversity.     

Isolation and characterization of nine polymorphic microsatellite loci in the endangered shrub Disanthus cercidifolius var. longipes (Hamamelidaceae)

Nine polymorphic microsatellite loci were isolated and characterized from an AC-enriched genomic library of Disanthus cercidifolius var. longipes. Microsatellite polymorphism was investigated using 24 individuals from one natural population. The observed number of alleles per locus ranged from two to four. Observed and expected heterozygosities ranged from 0.17 to 0.92 and from 0.16 to 0.72, respectively. These polymorphic microsatellite loci provide useful tools for the ongoing population genetic studies of D. cercidifolius var. longipes.     

Isolation and characterization of polymorphic microsatellite loci in a traditional Chinese medicinal plant, Schisandra sphenanthera

Schisandra sphenanthera (Schisandraceae) is a traditional Chinese medicinal plant. In this study, nine polymorphic microsatellite loci were developed and characterized for the species. A genomic DNA enrichment protocol was used to isolate microsatellite loci and polymorphism was explored using 36 individuals sampled from a natural population. The observed number of alleles ranged from 2 to 10 with an average of 5.2. Expected and observed heterozygosity ranged from 0.30 to 0.82 and 0.33 to 0.97, respectively. These microsatellites have been directly applied to both population and conservation genetic studies of S. sphenanthera.     

De novo development and characterization of polymorphic microsatellite markers in a schilbid catfish, <Emphasis Type="Italic">Silonia silondia</Emphasis> (Hamilton, 1822) and their validation for population genetic studies

The stock characterization of wild populations of Silonia silondia is important for its scientific management. At present, the information on genetic parameters of S. silondia is very limited. The species-specific microsatellite markers were developed in current study. The validated markers were used to genotype individuals from four distant rivers. To develop de novo microsatellite loci, an enriched genomic library was constructed for S. silondia using affinity–capture approach. The markers were validated for utility in population genetics. A total number of 76 individuals from four natural riverine populations were used to generate data for population analysis. The screening of isolated repeat sequences yielded eleven novel polymorphic microsatellite loci. The microsatellite loci exhibited high level of polymorphism, with 6–24 alleles per locus and the PIC value ranged from 0.604 to 0.927. The observed (Ho) and expected (He) heterozygosities ranged from 0.081 to 0.84 and 0.66 to 0.938, respectively. The AMOVA analysis indicated significant genetic differentiation among riverine populations (overall F_ST = 0.075; P < 0.0001) with maximum variation (92.5 %) within populations. Cross-priming assessment revealed successful amplification (35–38 %) of heterologous loci in four related species viz. Clupisoma garua, C. taakree, Ailia coila and Eutropiichthys vacha. The results demonstrated that these de novo polymorphic microsatellite loci are promising for population genetic variation and diversity studies in S. silondia. Cross-priming results indicated that these primers can help to get polymorphic microsatellite loci in the related catfish species of family Schilbidae.     

Population structure of the Southeast Asian river catfish Mystus nemurus

A total of 143 microsatellites were isolated from Mystus nemurus using a 5' anchored polymerase chain reaction technique or the random amplified hybridization microsatellite method, the first set of microsatellite markers developed for the Southeast Asian river catfish. Twenty polymorphic microsatellite loci were used as markers for population characterization of M. nemurus from six different geographical locations in Malaysia (Perak, Kedah, Johor, UPM, Sarawak and Terengganu). The number of alleles per locus ranged from 2 to 11 with 6.3 as the average number of alleles per locus. Characterization of the populations showed relatively high levels of genetic variation compared with previous studies using allozyme markers. The highest genetic similarity was found between Perak and Kedah, while the highest genetic distance was found between Terengganu and Kedah. The majority of clustering was in accordance with geographical locations and the histories of the populations. Microsatellite analysis indicated that the Sarawak population might be genetically closer to the Peninsular Malaysian populations than has been previously shown by other molecular marker studies.     

Isolation and characterization of 16 novel microsatellite loci in two inbred strains of the Chinese hamster (Cricetulus griseus)

The Shanyi inbred A and E strains of the Chinese hamster are widely used in biomedical research, but detailed genetic characterization has been lacking. We developed microsatellite markers that could be used for genetic diversity analysis and linkage map construction. We isolated and characterized 16 novel microsatellite loci from a microsatellite-enriched genomic DNA library. These loci were genotyped in 48 animals from the two strains, and the polymorphic information content was determined. In the Shanyi A and E populations, 14 and 15 loci were found to be polymorphic, respectively, with polymorphic information content ranging from 0.1393 to 0.8082 and from 0.1109 to 0.7397, respectively. A total of 115 alleles were found for the 16 microsatellite loci in the two populations; the mean observed heterozygosity (H(O)) was 0.5191 and 0.4333 for the A and E populations, respectively, indicating marked genetic variation within the two populations. Correspondingly, the F(ST) values ranged from 0.002 to 0.9253, with an overall mean of 0.1935, indicating significant genetic difference between the two strains. The population differentiation levels were substantiated by Nei's genetic distance and full Bayesian analyses computed with STRUCTURE. Despite the genetic diversity and differentiation within and between the two inbred populations, the 48 individuals were correctly allocated into their original populations with high statistical confidence based on these 16 microsatellite loci. These novel microsatellite loci should be useful genetic markers for these two Chinese hamster inbred strains.