中国蒙系绵羊品种间的基因流动

利用结构基因座和微卫星标记分析了中国蒙系绵羊4个品种间的基因流动情况。结果显示, 由结构基因座得出的遗传分化系数在0.0164 ~ 0.0455之间, 由微卫星位点得出的遗传分化系数在0.0107 ~ 0.0239之间, 说明遗传变异绝大部分存在于品种内, 蒙系绵羊品种间的遗传分化水平很低。结构基因座(N_m = 7.971)和微卫星位点(N_m = 15.732)都反映出品种间的基因流通畅。品种间的遗传差异与地理距离之间无直接相关关系。初步推断我国蒙系绵羊品种间的遗传分化主要是自然选择(生境异质性)作用的结果。     

Gene pool of pig breeds in southern region of Ukraine as determined from immunogenetic parameters

On the basis of the long-term observations of 22 334 pedigree animals, the level of genetic polymorphism and basic breed-specific immunogenetic parameters were determined in eight major pig breeds from southern Ukraine. The high level of gene diversity was revealed and the degree of genetic similarity between the studied breeds was estimated.     

Analysis of conservation priorities of Iberoamerican cattle based on autosomal microsatellite markers

Background

Determining the value of livestock breeds is essential to define conservation priorities, manage genetic diversity and allocate funds. Within- and between-breed genetic diversity need to be assessed to preserve the highest intra-specific variability. Information on genetic diversity and risk status is still lacking for many Creole cattle breeds from the Americas, despite their distinct evolutionary trajectories and adaptation to extreme environmental conditions.

Methods

A comprehensive genetic analysis of 67 Iberoamerican cattle breeds was carried out with 19 FAO-recommended microsatellites to assess conservation priorities. Contributions to global diversity were investigated using alternative methods, with different weights given to the within- and between-breed components of genetic diversity. Information on Iberoamerican plus 15 worldwide cattle breeds was used to investigate the contribution of geographical breed groups to global genetic diversity.

Results

Overall, Creole cattle breeds showed a high level of genetic diversity with the highest level found in breeds admixed with zebu cattle, which were clearly differentiated from all other breeds. Within-breed kinships revealed seven highly inbred Creole breeds for which measures are needed to avoid further genetic erosion. However, if contribution to heterozygosity was the only criterion considered, some of these breeds had the lowest priority for conservation decisions. The Weitzman approach prioritized highly differentiated breeds, such as Guabalá, Romosinuano, Cr. Patagonico, Siboney and Caracú, while kinship-based methods prioritized mainly zebu-related breeds. With the combined approaches, breed ranking depended on the weights given to the within- and between-breed components of diversity. Overall, the Creole groups of breeds were generally assigned a higher priority for conservation than the European groups of breeds.

Conclusions

Conservation priorities differed significantly according to the weight given to within- and between-breed genetic diversity. Thus, when establishing conservation programs, it is necessary to also take into account other features. Creole cattle and local isolated breeds retain a high level of genetic diversity. The development of sustainable breeding and crossbreeding programs for Creole breeds, and the added value resulting from their products should be taken into consideration to ensure their long-term survival.     

Genetic Polymorphism of Russian,European, and Asian Chicken Breeds as Revealed with DNA and Protein Markers

The variation in polymorphic DNA (RAPD and minisatellite) and protein markers was compared for nine Russian chicken breeds differing in morphological and productivity types and in origin, three European egg breeds, and three meat breeds of the Asian origin. Genetic diversity indices were calculated for each breed group and each marker type and were used to construct dendrograms of genetic similarity. In all breed groups, minisatellites and RAPD markers revealed higher genetic diversity as compared with protein markers. With any type of markers, genetic diversity of the Russian and Asian meat breeds proved to be significantly higher than that of the European egg breeds. The differentiating potentialities of molecular and genetic biochemical markers at the breed level and the origin of the Russian chicken breeds are discussed.     

Genetic polymorphism of Russian,European, and Asian chicken breeds as revealed with DNA and protein markers

The variation in polymorphic DNA (RAPD and minisatellite) and protein markers was compared for nine Russian chicken breeds differing in morphological and productivity types and in origin, three European egg breeds, and three broiler breeds of the Asian origin. Genetic diversity indices were calculated for each breed group and each marker type and were used to construct dendrograms of genetic similarity. In all breed groups, minisatellites and RAPD markers revealed higher genetic diversity as compared with protein markers. With any type of markers, genetic diversity of the Russian and Asian broiler breeds proved to be significantly higher than that of the European egg breeds. The differentiating potentialities of molecular and genetic biochemical markers at the breed level and the origin of the Russian chicken breeds are discussed.     

Genetic diversity and population structure of indigenous yellow cattle breeds of China using 30 microsatellite markers

Twenty-seven domesticated yellow cattle breeds of China and three introduced cattle breeds were analysed by means of 30 microsatellite markers to determine the level of genetic variation within and among populations as well as the population structure. In all, 480 microsatellite alleles were observed across the 30 breeds with the mean number of alleles per locus of 9.093 for native breeds and 6.885 for the three introduced breeds. Mean F -statistics (0.08) for Chinese native cattle breeds implied that 92% of the total genetic variation was from genetic differentiation within each breed and 8% of the genetic variation existed among breeds. A phylogenetic tree was constructed based on Nei's genetic distances, and three clusters were obtained. According to the tree, the three introduced breeds were distinct from the 27 native breeds. The indigenous cattle breeds were divided into two clusters, one cluster including five humpless breeds and the other cluster containing 22 humped breeds. This study identifies multiple origins of yellow cattle of China from Bos taurus and Bos indicus . Furthermore, population structure analysis implies that there are possibly five independent original domestications for yellow cattle in China. Four of five origins were four different Bos indicus types, mainly in areas of the Chang Jiang, the Zhu Jiang River basin, the Yellow River and the Huai River basin. The other origin was for Bos taurus type of Mongolian descent, mainly located in Northwestern China, the Mongolian plateau and Northeastern China or north of the Great Wall.     

Characterization of the Russian beef cattle breed gene pools using inter simple sequence repeat DNA analysis (ISSR analysis)

The gene pools of beef cattle breeds bred in Russia were characterized on the basis of inter simple sequence repeat DNA analysis (ISSR analysis). Samples of Aberdeen Angus, Kalmyk, and Kazakh Whitehead breeds from Russia, as well as of Hereford breed, hybrids of Kazakh Whitehead and Hereford breeds, and Kazakh Whitehead breed from the Republic of Kazakhstan, were examined. In the examined breeds, 27 AG-ISSR fragments were identified, 25 of which were polymorphic. The examined breeds were different both in the fragment profiles (the presence/absence of individual ISSR fragments) and in their frequencies. It was demonstrated that the hybrid animals lacked some ISSR fragments that were present with high frequencies in parental forms, suggesting considerable genome rearrangement in the hybrid animals (at the regions of microsatellite localization) in crossings of the individuals from different breeds. The level of genetic diversity in Russian beef breeds was consistent with the values typical of farmed populations (breeds). The genetic diversity parameters assessed by applying Nei’s gene diversity index and the Shannon index varied from 0.0218 to 0.0605 and from 0.0225 to 0.0819, respectively. The highest Shannon index value was detected in the Kalmyk breed (0.0837) and Kazakh Whitehead breed from Russia (0.0819), and the highest level of Nei’s gene diversity index was found in the Kalmyk breed (0.0562) and in both populations of the Kazakh Whitehead breed (0.0509 and 0.0605). The high level of genetic similarity (according to Nei) was revealed between Russian beef cattle breeds and Hereford cattle: 0.839 (for the Kazakh Whitehead breed from Russia) and 0.769 (for the Kalmyk breed).     

Genetic characterization of four native Italian shepherd dog breeds and analysis of their relationship to cosmopolitan dog breeds using microsatellite markers

Very little research into genetic diversity of Italian native dog breeds has been carried out so far. In this study we aimed to estimate and compare the genetic diversity of four native Italian shepherd dog breeds: the Maremma, Bergamasco, Lupino del Gigante and Oropa shepherds. Therefore, some cosmopolitan dog breeds, which have been widely raised in Italy for a long time past, have also been considered to check possible influence of these dog populations on the Italian autochthonous breeds considered here. A total of 212 individuals, belonging to 10 different dog breeds, were sampled and genotyped using 18 autosomal microsatellite loci. We analyzed the genetic diversity of these breeds, within breed diversity, breed relationship and population structure. The 10 breeds considered in this study were clearly genetically differentiated from each other, regardless of current population sizes and the onset of separate breeding history. The level of genetic diversity explained 20% of the total genetic variation. The level of H_E found here is in agreement with that found by other studies. The native Italian breeds showed generally higher genetic diversity compared with the long established, well-defined cosmopolitan dog breeds. As the Border Collie seems closer to the Italian breeds than the other cosmopolitan shepherd dogs considered here, a possible utilization of this breed to improve working performance in Italian traditional working shepherd dogs cannot be ignored. The data and information found here can be utilized in the organization of conservation programs planned to reduce inbreeding and to minimize loss of genetic variability.     

Differentiation of European cattle by AFLP fingerprinting

The Neolithic introduction of domestic cattle into Europe was followed by differential adaptation, selection, migration and genetic isolation, leading ultimately to the emergence of specialized breeds. We have studied the differentiation of European cattle by amplified fragment length polymorphism (AFLP) fingerprinting. Combining AFLP data sets from two laboratories yielded 81 biallelic polymorphic markers scored in 19-22 individual animals from 51 breeds. Model-based clustering differentiated Podolian cattle as well as French and Alpine breeds from other European cattle. AFLP genetic distances correlated well with microsatellite-based genetic distances calculated for the same breeds. However, the AFLP data emphasized the divergence of taurine and indicine cattle relative to the variation among European breeds and indicated an Eastern influence on Italian and Hungarian Podolian breeds. This probably reflects import from the East after the original introduction of domestic cattle into Europe. Our data suggest that Italian cattle breeds are relatively diverse at the DNA sequence level.     

Analysis of genetic diversity and population structure of Chinese yak breeds （Bos grunniens） using microsatellite markers

Nine Chinese yak breeds (Maiwa,Tianzhu White,Qinghai Plateau,Sibu,Zhongdian,Pall,Tibetan High Mountain,Jiulong,and Xin-jiang) and Gayal were analyzed by means of 16 microsatellite markers to determine the level of genetic variation within populations,genetic relationship between populations,and population structure for each breed.A total of 206 microsatellite alleles were observed.Mean F-statistics (0.056) for 9 yak breeds indicated that 94.4% of the genetic variation was observed within yak breeds and 5.6% of the genetic variation existed amongst breeds.The Neighbor-Joining phylogenetic free was constructed based on Nei's standard genetic dis-tances and two clusters were obtained.The Gayal separated from the yaks far away and formed one cluster and 9 yak breeds were grouped together.The analysis of population structure for 9 yak breeds and the Gayal showed that they resulted in four clusters; one clus-ter includes yaks from Tibet Autonomous Region and Qinghai Province,one cluster combines Zhongdian,Maiwa,and Tianzhu White,and Jiulong and Xinjiang come into the third cluster.Pali was mainly in the first cluster (90%),Jiulong was mainly in the second cluster (87.1%),Zhongdian was primarily in the third cluster (83%),and the other yak breeds were distributed in two to three clusters.The Gayal was positively left in the fourth cluster (99.3%).     

Genetic diversity among chicken breeds estimated through randomly amplified polymorphic DNA.

The randomly amplified polymorphic DNA (RAPD) markers were used to detect polymorphism among five breeds of chicken i.e. White Leghorn and Rhodes Island Red (selected for part period egg production and egg mass respectively), Red Cornish and White Plymouth Rock (selected for early body weights) and Kadaknath (native breed). Twelve of the fifty random primers screened yielded distinct polymorphic RAPD profiles. Of the total 96 fragments amplified, about 25% showed polymorphism. Using the RAPD data matrix, the within population and between population genetic similarity was estimated. The selected improved breeds showed higher within population genetic similarity in comparison to the native breed. The two meat type breeds showed a high level of genetic similarity between themselves. The White Leghorn breed showed a low genetic similarity with other breeds. The native breed showed highest similarity with Rhodes Island Red. The dendogram was constructed to show phylogenetic relationship among these breeds. As expected, the genetic distances were lowest within similar type breeds and were highest between dissimilar type breeds. The results indicated the effectiveness of RAPD in detecting polymorphism between chicken populations and their applicability in population studies and establishing genetic relationships among the chicken populations.     

Conservation genetics of cattle, sheep, and goats

Cattle, sheep and goats were domesticated about 10,000 years ago, spread out of the domestication centers in Europe, Asia, and Africa during the next few thousands years, and gave many populations locally adapted. After a very long period of soft selection, the situation changed dramatically 200 years ago with the emergence of the breed concept. The selection pressure strongly increased, and the reproduction among breeds was seriously reduced, leading to the fragmentation of the initial gene pool. More recently, the selection pressure was increased again via the use of artificial insemination, leading to a few industrial breeds with very high performances, but with low effective population sizes. Beside this performance improvement of industrial breeds, genetic resources are being lost, because of the replacement of traditional breeds by high performance industrial breeds at the worldwide level, and because of the loss of genetic diversity in these industrial breeds. Many breeds are already extinct, and genetic resources in cattle, sheep, and goats are thus highly endangered, particularly in developed countries. The recent development of next generation sequencing technologies opens new avenues for properly characterizing the genetic resources, not only in the very diverse domestic breeds, but also in their wild relatives. Based on sound genetic characterization, urgent conservation measures must be taken to avoid an irremediable loss of farm animal genetic resources, integrating economical, sociological, and political parameters.     

Molecular structure in peripheral dog breeds: Portuguese native breeds as a case study

Genetic variability in purebred dogs is known to be highly structured, with differences among breeds accounting for ∼30% of the genetic variation. However, analysis of the genetic structure in non-cosmopolitan breeds and local populations is still limited. Nine Portuguese native dog breeds, and other peripheral dog populations (five) with regional affinities, were characterized using 16 microsatellites and 225 amplified fragment length polymorphism (AFLP) markers, and the pattern of genetic differentiation was investigated. Although the level of breed differentiation detected is below that of other dog breeds, there is in most cases a correlation between breed affiliation and molecular structure. AFLP markers and Bayesian clustering methods allowed an average of 73.1% of individuals to be correctly assigned to source populations, providing robust genotypic assessment of breed affiliation. A geographical genetic structure was also detected, which suggests a limited influence of African dogs on the Iberian breeds. The sampling effect on the estimation of population structure was evaluated and there was a 2.2% decrease in genetic differentiation among breeds when working animals were included. Genetic diversity of stray dogs was also assessed and there is no evidence that they pose a threat to the preservation of the gene pool of native dog breeds.     

Geographical partitioning of goat diversity in Europe and the Middle East

Thirty microsatellite markers were analysed in 1426 goats from 45 traditional or rare breeds in 15 European and Middle Eastern countries. In all populations inbreeding was indicated by heterozygosity deficiency (mean FIS = 0.10). Genetic differentiation between breeds was moderate with a mean FST value of 0.07, but for most (c. 71%) northern and central European breeds, individuals could be assigned to their breeds with a success rate of more than 80%. Bayesian-based clustering analysis of allele frequencies and multivariate analysis revealed at least four discrete clusters: eastern Mediterranean (Middle East), central Mediterranean, western Mediterranean and central/northern Europe. About 41% of the genetic variability among the breeds could be explained by their geographical origin. A decrease in genetic diversity from the south-east to the north-west was accompanied by an increase in the level of differentiation at the breed level. These observations support the hypothesis that domestic livestock migrated from the Middle East towards western and northern Europe and indicate that breed formation was more systematic in north-central Europe than in the Middle East. We propose that breed differentiation and molecular diversity are independent criteria for conservation.     

Genetic diversity and relationships of Portuguese and other horse breeds based on protein and microsatellite loci variation

There are three native Portuguese horse breeds: Lusitano, Sorraia and Garrano. This study compares diversity patterns of 17 protein and 12 microsatellite markers in these three as well as 30 other breeds to infer relationships among the breeds and to compare levels of polymorphism of these breeds for use in conservation efforts. The Garrano and the Lusitano showed a high level of genetic diversity, similar to that observed for most of the other analysed breeds, while the Sorraia and Friesian breeds showed low levels of variation for both genetic marker types. The combined protein and microsatellite data produced a tree that fit historical records well and with greater confidence levels than those for either data set alone. The combined genetic diversity and relationship information provides important baseline data for future breed conservation efforts, especially for a critically endangered breed such as the Sorraia.     

Molecular phylogeny of Indian horse breeds with special reference to Manipuri pony based on mitochondrial D-loop

Manipuri pony is the geographically distant breed of horse from the five recognized horse breeds found in the Indian subcontinent. The phylogenetic relationship of Manipuri pony with the other breeds is unknown. The diversity in the mitochondrial (mt) DNA D-loop region is employed as an important tool to understand the origin and genetic diversification of domestic horses and to examine genetic relationships among breeds around the world. This study was carried out to understand the maternal lineages of Manipuri pony using the 247 bp region of the mtDNA D-loop. The dataset comprised of eleven numbers of self developed sequences of Manipuri pony, 59 and 35 number of retrieved sequences of Indian horse breeds and other worldwide breeds respectively. A total of 35 haplotypes was identified with a high level of genetic diversity in the Indian breeds. A total of seven major mtDNA haplogroups (A–G) was identified in the Indian horse breeds that indicated the abundance of mtDNA diversity and multiple origins of maternal lineages in them. The majority of the studied sequences of Indian breeds (33.3 %) were grouped into haplogroup D and least (3.9 %) in haplogroup E. The Manipuri breed showed the least F_ST distance (0.03866) with the most diverged Indian breeds and with Thoroughbred horse among the worldwide. This study indicated a close association between Manipuri pony and Thoroughbred.     

Evaluation of Genetic Differentiation in Bos indicus Cattle Breeds from Marathwada Region of India Using Microsatellite Polymorphism

Elucidation of genetic variability and genetic relationship among breeds has direct relevance with the issues of sustainable use of domestic animal genetic resources. In the present study, genetic polymorphism was evaluated using 22 microsatellite loci in unrelated samples of Red Kandhari and Deoni cattle breeds inhabiting the same geographical area of Marathwada region in Maharashtra state (western India). This work was mainly aimed at assessing the current genetic diversity to understand whether the two zebu populations in question are genetically differentiated. A total of 164 alleles were detected with an average of 5.82 and 5.86 alleles per locus (MNA) in Red Kandhari and Deoni breeds, respectively. The estimated mean observed (Ho) and expected (He) heterozygosity were 0.47 and 0.64 in Red Kandhari vs. 0.57 and 0.69 in Deoni cattle, respectively, demonstrating considerable level of genetic variation in both the populations. Mean estimates of F statistics were: F (FIT) = 0.315±0.035, f(FIS) = 0.231±0.031, θ(FST) = 0.110±0.022, with both the breeds exhibiting significant deficit of heterozygotes (FIS = 0.179 in Deoni; 0.278 in Red Kandhari). The multilocus FST values implied that 11.0% of the total genetic variation corresponds to breed and were statistically greater than zero for the two populations, suggesting population division. The evaluation of exact test also indicated that allele frequencies across all the loci differed significantly (P < 0.001) between two zebu breeds, further supporting population differentiation. Different genetic distance measures showed considerable levels of distances between the two cattle breeds (0.318 = Nei's standard DS; 0.250 = Nei's DA; 0.416 = Cavalli-Sforza and Edwards's DC; 0.164 = Reynold's, and 2.64 = Delta mu square (dμ)2. Bayesian statistical approach to assign each individual to the population also supported considerable differentiation between the two cattle breeds, possibly reflecting the limited gene flow between the two Marthwada cattle populations. The existence of cohesive breeding structure of both the breeds was further substantiated by allele-sharing distance measures (DAS) among individual animals. The results of this study thus revealed that the two Bos indicus breeds sharing the common breeding tracts are genetically differentiated enough as separate breeds.     

Evaluation of genetic differentiation in Bos indicus cattle breeds from Marathwada region of India using microsatellite polymorphism

Elucidation of genetic variability and genetic relationship among breeds has direct relevance with the issues of sustainable use of domestic animal genetic resources. In the present study, genetic polymorphism was evaluated using 22 microsatellite loci in unrelated samples of Red Kandhari and Deoni cattle breeds inhabiting the same geographical area of Marathwada region in Maharashtra state (western India). This work was mainly aimed at assessing the current genetic diversity to understand whether the two zebu populations in question are genetically differentiated. A total of 164 alleles were detected with an average of 5.82 and 5.86 alleles per locus (MNA) in Red Kandhari and Deoni breeds, respectively. The estimated mean observed (Ho) and expected (He) heterozygosity were 0.47 and 0.64 in Red Kandhari vs. 0.57 and 0.69 in Deoni cattle, respectively, demonstrating considerable level of genetic variation in both the populations. Mean estimates of F statistics were: F (FIT) = 0.315 +/- 0.035, f(FIS) = 0.231 +/- 0.031, theta(FST) = 0.110 +/- 0.022, with both the breeds exhibiting significant deficit of heterozygotes (FIS = 0.179 in Deoni; 0.278 in Red Kandhari). The multilocus FST values implied that 11.0% of the total genetic variation corresponds to breed and were statistically greater than zero for the two populations, suggesting population division. The evaluation of exact test also indicated that allele frequencies across all the loci differed significantly (P < 0.001) between two zebu breeds, further supporting population differentiation. Different genetic distance measures showed considerable levels of distances between the two cattle breeds (0.318 = Nei's standard DS; 0.250 = Nei's DA; 0.416 = Cavalli-Sforza and Edwards's Dc; 0.164 = Reynold's, and 2.64 = Delta mu square (dmicro)2. Bayesian statistical approach to assign each individual to the population also supported considerable differentiation between the two cattle breeds, possibly reflecting the limited gene flow between the two Marthwada cattle populations. The existence of cohesive breeding structure of both the breeds was further substantiated by allele-sharing distance measures (DAS) among individual animals. The results of this study thus revealed that the two Bos indicus breeds sharing the common breeding tracts are genetically differentiated enough as separate breeds.     

SNP discovery and population structure analysis in Lassi and Marecha camel breeds using a genotyping by sequencing method

Pakistani camels have been classified socio-geographically into 20 breeds, but they have not yet been subjected to substantial selective pressures and the genetic basis for these breeds is not understood. However, it should be possible to distinguish them by use of molecular data. This study investigated the genetic diversity and population structure within and between two major Pakistani camel breeds, Marecha and Lassi. As no SNP array is currently available, we first identified 63 619 SNPs using a genotyping by sequencing approach. After quality control, a panel of 36 926 SNPs was used in the analysis. Population structure was investigated with a principal coordinate analysis as well as a cluster analysis using NetView , and multilocus heterozygosity analysis to explore between- and within-breed genetic variation. In addition, between-breed variation was explored using the fixation index, F_ST. We also compared relationship matrices computed using the VanRaden SNP-based method and a method developed specifically for genotyping by sequencing data. Among the two camel breeds, Lassi showed a lower level of genetic diversity whereas Marecha showed a higher level. As a genotyping platform has not yet been developed for the camel, the SNPs discovered in this study will be useful in future genetic studies in camels.     

我国主要地方绵羊品种随机扩增多态DNA研究

对蒙古羊、湖羊、滩羊、小尾寒羊、乌珠穆沁羊、藏绵羊、阿勒泰羊7个地方绵羊品种和无角陶赛特羊、德国美利奴羊、萨福克羊3个引入品种基因组DNA进行了RAPD分析。结果表明：（1）RAPD可作为一种有效的标记用于绵羊品种之间遗传亲缘关系的分析。（2）在所使用的43种随机引物中,有35种引物扩增出多态谱带,多态频率为66.24%,说明RAPD技术用于研究绵羊核DNA的遗传变异具有较高的检出率和灵敏度。（3）总群体平均遗传多样性指数（HSP)为0.9139,说明绵羊群体具有较为丰富的遗传多样性。（4）我国地方绵羊品种间的分子聚类关系与其所处的地理位置、考古学结果,以及细胞遗传学研究结果基本,引入品种间的分子聚类关系也与其育成史基本一致。