STR Polymorphism in Indigenous Daghestan Populations

Genomic diversity of 21 STR loci has been studied in six ethnic populations of Daghestan (the Caucasus), namely, Avars, Dargins, Kubachians, Lezgins, Kumiks, and Nogais, and the results have been compared with these data for European, African, and East Asian ethnic groups. Daghestan is unique in its ethnic diversity, which is the greatest in the Caucasus: 26 out of approximately 50 autochthonous ethnic groups of the Caucasus live there. The genetic origin of this wide ethnic diversity of Daghestan and the Caucasus as a whole is still obscure. The genetic heterogeneity of Daghestan populations has been found to be lower than that of most other populations in the world. This is explained by a prolonged isolation and gene drift in their demographic history. Generalized genetic distances between ethnic groups calculated for the whole set of loci studied allow differentiating Asian populations from African ones, with European populations occupying intermediate positions. All Daghestan ethnic populations form a distinct common group together with some European populations (Finnish, Polish, and French). Nogais are genetically close to Southeast Asian populations. The genetic closeness and the apparently equal genetic diversity of Daghestan and European populations suggest that the ethnic differentiation of the ancestral populations of Daghestan and European ethnic groups occurred in the earliest populations of modern humans.     

STR polymorphism in populations of indigenous Daghestan ethnic groups

Genomic diversity of 21 STR loci has been studied in six ethnic populations of Daghestan (the Caucasus), namely, Avars, Dargins, Kubachians, Lezgins, and Nogais, and the results have been compared with these data for European, African, and East Asian ethnic groups. Daghestan is unique in its ethnic diversity, which is the greatest in the Caucasus: 26 out of approximately 50 autochthonous ethnic groups of the Caucasus live there. The genetic origin of this wide ethnic diversity of Daghestan and the Caucasus as a whole is still obscure. The genetic heterogeneity of Daghestan populations has been found to be lower than that of most other populations in the world. This is explained by a prolonged isolation and gene drift in their demographic history. Generalized genetic distances between ethnic groups calculated for the whole set of loci studied allow differentiating Asian populations from African ones, with European populations occupying intermediate positions. All Daghestan ethnic populations form a distinct common group together with some European populations (Finnish, Polish, and French). Nogais are genetically close to Southeast Asian populations. The genetic closeness and the apparently equal genetic diversity of Daghestan and European populations suggest that the ethnic differentiation of the ancestral populations of Daghestan and European ethnic groups occurred in the earliest populations of modern humans.     

Genetic polymorphism of mitochondrial DNA HVS-I and HVS-Ⅱ of Chinese Tu ethnic minority group

We analyzed the two hypervariable segments HVS-Ⅰ and HVS-Ⅱ of 108 Chinese Tu ethnic minority group samples for forensic and population genetics purposes.Comparing with Anderson sequence,79 polymorphic loci in HVS-Ⅰ and 40 in HVS-Ⅱ were found in Chi-nese Tu ethnic minority group mtDNA sequences,and 90 and 64 haplotypes were then defined.Haplotype diversity and the mean pair-wise differences were 0.9903±0.0013 and 5.7785 in HVS-Ⅰ,and 0.9777±0.0013 and 3.5819 in HVS-Ⅱ,respectively.By analyzing the hypervariable domain from nucleotide 1,6180 to 1,6193 in HVS-Ⅰ,we defined some new types of sequence variations.We also compared the relationship between Tu population and other populations using mtDNA HVS-Ⅰ sequences.According to Rst genetic distances,the phylogenetic tree showed that the Tu population,the Xi'an Han population,the Chinese Korean,and the Mongol ethnic group were in a clade.This indicated a close genetic relationship between them.There were far relations between the Tu population and other Chinese southern Han populations,Siberian,European,African,and other foreign populations.The results suggest that Tu population has a multi-origin and has also merged with other local populations.     

中国家驴的非洲起源研究

对我国13个家驴品种367条序列(其中引用文献资料241条)的mtDNA D-loop 区399 bp进行分析, 共检测到96种单倍型57个多态位点, 其单倍型多样度为0.767~0.967, 核苷酸多样度为0.014~0.032, 表明我国家驴的遗传多态性丰富。与3个努比亚野驴、3个索马里野驴和6个亚洲野驴的序列构建 NJ系统发育树, 证明我国家驴的母系起源为非洲野驴中的索马里驴和努比亚驴, 亚洲野驴不是中国家驴的母系祖先。     

Length variations in the COII-tRNA(Lys) intergenic region of mitochondrial DNA in Indonesian populations.

The prevalence of a 9-base-pair (bp) deletion between the mitochondrial cytochrome oxidase II (MTCOX*2) and lysine tRNA (MTTK) genes (region V) has been used to estimate the genetic relationships among Asian and Pacific populations. Many East Asian and Pacific Island populations have been examined previously, but the mitochondrial DNA (mtDNA) diversity of the intervening Indonesian archipelago has not previously been systematically examined. The 17,500 islands of Indonesia currently contain nearly 213 million people and extensive cultural, linguistic, and, presumably, genetic diversity. This study of 1091 individuals representing 15 ethnic groups is the most extensive mtDNA survey to date of the Indonesian archipelago. Six distinct length polymorphisms in region V were observed within these 15 populations. The 9-bp deletion was found in every population examined at frequencies comparable to those of previously examined East Asian populations and substantially lower than those in most Pacific Island populations. Despite the inclusion of Austronesian-speaking populations and a Papuan-speaking population, there was no statistically significant heterogeneity in the frequency of the 9-bp deletion among the 15 populations (p = 0.09). These data indicate that substantial gene flow occurred among the populations at some time in the past. Our observations of no significant correlations between genetic and geographic distances (r = -0.04, p = 0.53) coupled with the extensive cultural and linguistic differences currently within the archipelago suggest that little gene flow among neighboring populations has occurred recently.     

Global diversity and genetic contributions of chicken populations from African,Asian and European regions

Genetic diversity and population structure of 113 chicken populations from Africa, Asia and Europe were studied using 29 microsatellite markers. Among these, three populations of wild chickens and nine commercial purebreds were used as reference populations for comparison. Compared to commercial lines and chickens sampled from the European region, high mean numbers of alleles and a high degree of heterozygosity were found in Asian and African chickens as well as in Red Junglefowl. Population differentiation (F_ST) was higher among European breeds and commercial lines than among African, Asian and Red Junglefowl populations. Neighbour‐Net genetic clustering and structure analysis revealed two main groups of Asian and north‐west European breeds, whereas African populations overlap with other breeds from Eastern Europe and the Mediterranean region. Broilers and brown egg layers were situated between the Asian and north‐west European clusters. structure analysis confirmed a lower degree of population stratification in African and Asian chickens than in European breeds. High genetic differentiation and low genetic contributions to global diversity have been observed for single European breeds. Populations with low genetic variability have also shown a low genetic contribution to a core set of diversity in attaining maximum genetic variation present from the total populations. This may indicate that conservation measures in Europe should pay special attention to preserving as many single chicken breeds as possible to maintain maximum genetic diversity given that higher genetic variations come from differentiation between breeds.     

Markers for mapping by admixture linkage disequilibrium in African American and Hispanic populations

Population linkage disequilibrium occurs as a consequence of mutation, selection, genetic drift, and population substructure produced by admixture of genetically distinct ethnic populations. African American and Hispanic ethnic groups have a history of significant gene flow among parent groups, which can be of value in affecting genome scans for disease-gene discovery in the case-control and transmission/disequilibrium test designs. Disease-gene discovery using mapping by admixture linkage disequilibrium (MALD) requires a map of polymorphic markers that differentiate between the founding populations, along with differences in disease-gene allele frequencies. We describe markers appropriate for MALD mapping by assessing allele frequencies of 744 short tandem repeats (STRs) in African Americans, Hispanics, European Americans, and Asians, by choosing STR markers that have large differences in composite delta, log-likelihood ratios, and/or I*(2) for MALD. Additional markers can be added to this MALD map by utilization of the rapidly growing single-nucleotide-polymorphism databases and the literature, to achieve a 3-10-cM scanning scale. The map will be useful for studies of diseases, including prostate and breast cancer, diabetes, hypertension, and end-stage renal disease, that have large differences in incidence between the founding populations of either Hispanics or African Americans.     

Reduced-median-network analysis of complete mitochondrial DNA coding-region sequences for the major African, Asian, and European haplogroups

The evolution of the human mitochondrial genome is characterized by the emergence of ethnically distinct lineages or haplogroups. Nine European, seven Asian (including Native American), and three African mitochondrial DNA (mtDNA) haplogroups have been identified previously on the basis of the presence or absence of a relatively small number of restriction-enzyme recognition sites or on the basis of nucleotide sequences of the D-loop region. We have used reduced-median-network approaches to analyze 560 complete European, Asian, and African mtDNA coding-region sequences from unrelated individuals to develop a more complete understanding of sequence diversity both within and between haplogroups. A total of 497 haplogroup-associated polymorphisms were identified, 323 (65%) of which were associated with one haplogroup and 174 (35%) of which were associated with two or more haplogroups. Approximately one-half of these polymorphisms are reported for the first time here. Our results confirm and substantially extend the phylogenetic relationships among mitochondrial genomes described elsewhere from the major human ethnic groups. Another important result is that there were numerous instances both of parallel mutations at the same site and of reversion (i.e., homoplasy). It is likely that homoplasy in the coding region will confound evolutionary analysis of small sequence sets. By a linkage-disequilibrium approach, additional evidence for the absence of human mtDNA recombination is presented here.     

Genome-wide SNP typing reveals signatures of population history

Single-nucleotide polymorphism (SNP) arrays have become a popular technology for disease-association studies, but they also have potential for studying the genetic differentiation of human populations. Application of the Affymetrix GeneChip Human Mapping 500K Array Set to a population of 102 individuals representing the major ethnic groups in the United States (African, Asian, European, and Hispanic) revealed patterns of gene diversity and genetic distance that reflected population history. We analyzed allelic frequencies at 388,654 autosomal SNP sites that showed some variation in our study population and 10% or fewer missing values. Despite the small size (23-31 individuals) of each subpopulation, there were no fixed differences at any site between any two subpopulations. As expected from the African origin of modern humans, greater gene diversity was seen in Africans than in either Asians or Europeans, and the genetic distance between the Asian and the European populations was significantly lower than that between either of these two populations and Africans. Principal components analysis applied to a correlation matrix among individuals was able to separate completely the major continental groups of humans (Africans, Asians, and Europeans), while Hispanics overlapped all three of these groups. Genes containing two or more markers with extraordinarily high genetic distance between subpopulations were identified as candidate genes for health differences between subpopulations. The results show that, even with modest sample sizes, genome-wide SNP genotyping technologies have great promise for capturing signatures of gene frequency difference between human subpopulations, with applications in areas as diverse as forensics and the study of ethnic health disparities.     

Polymorphic Admixture Typing in Human Ethnic Populations

A panel of 257 RFLP loci was selected on the basis of high heterozygosity in Caucasian DNA surveys and equivalent spacing throughout the human genome. Probes from each locus were used in a Southern blot survey of allele frequency distribution for four human ethnic groups: Caucasian, African American, Asian (Chinese), and American Indian (Cheyenne). Nearly all RFLP loci were polymorphic in each group, albeit with a broad range of differing allele frequencies (δ). The distribution of frequency differences (δ values) was used for three purposes: (1) to provide estimates for genetic distance (differentiation) among these ethnic groups, (2) to revisit with a large data set the proportion of human genetic variation attributable to differentiation within ethnic groups, and (3) to identify loci with high δ values between recently admixed populations of use in mapping by admixture linkage disequilibrium (MALD). Although most markers display significant allele frequency differences between ethnic groups, the overall genetic distances between ethnic groups were small (.066–.098), and <10% of the measured overall molecular genetic diversity in these human samples can be attributed to “racial” differentiation. The median δ values for pairwise comparisons between groups fell between .15 and .20, permitting identification of highly informative RFLP loci for MALD disease association studies.     

Phylogenetic information in polymorphic L1 and Alu insertions from East Asians and Native American populations

This study attempts to ascertain genetic affinities between Native American and East Asian populations by analyzing four polymorphic Alu insertions (PAIs) and three L1 polymorphic loci. These two genetic systems demonstrated strong congruence when levels of diversity and genetic distances were considered. Overall, genetic relatedness within Native American groups does not correlate with geographical and linguistic structure, although strong grouping for Native Americans with East Asians was demonstrated, with clear discrimination from African and European groups. Most of the variation was assigned to differences occurring within groups, but the interpopulation variation found for South Amerindians was recognizably higher in comparison to the other sampled groups of populations. Our data suggest that bottleneck events followed by strong influence of genetic drift in the process of the peopling of the Americas may have been determinant factors in delineating the genetic background of present-day South Amerindians. Since no clear subgroups were detected within Native Americans and East Asians, there is no indication of multiple waves in the early colonization of the New World.     

Genetic diversity and phylogenetic relationship among the western and the Asian honey bees based on two mitochondrial gene segments (COI and ND5)

The Asian honey bee species i.e., Apis cerana (the eastern honey bee), A. dorsata (the giant honey bee), and the western or European honey bee (A. mellifera) collected from Pakistan were studied using partial sequences from two mitochondrial genes (i) the Cytochrome c oxidase I (COI) and (ii) the mitochondrially encoded NADH dehydrogenase 5 (ND5) and then compared with other honey bees sequences (already submitted from different countries around the globe) obtained after the national center for biotechnology information (NCBI). DNA sequences were analyzed employing molecular evolutionary genetics analysis and Kimura 2-parameter model, neighbor-joining method was applied to investigate phylogenetic relationships, and DNA sequence polymorphism was applied to measure the genetic diversity within the genus Apis. The phylogenetic analyses yielded consistent results. Based on COI gene fragment in two Asian and European honey bee species from Pakistan and from other countries showed considerable genetic diversity levels and deviation among the species. While in contrast the phylogenetic analyses based on ND5 gene fragment in Asian and European honey bee species from Pakistan and other countries showed comparatively higher genetic diversity indices and variations than the COI gene. So, in the genus Apis, the mitochondrial ND5 region has shown the possibility to answer the interactions among species. A further detailed work (by linking the analysis of other genomic and mitochondrial genes) is required for good quality solution to establish the concise genetic diversity and interaction among the Apis species. The objective of this study was to explore the extent of genetic differences and phylogenetic links among the three kinds of honey bee species from Pakistan and comparing them with other bee species around the globe.     

Estimates of African, European and Native American ancestry in Afro-Caribbean men on the island of Tobago

BACKGROUND/AIMS: The Tobago Afro-Caribbean population is a valuable resource for studying the genetics of diseases that show significant differences in prevalence between populations of African descent and populations of other ancestries. Empirical confirmation of low European and Native American admixture may help in clarifying the ethnic variation in risk for such diseases. We hypothesize that the degree of European and Native American admixture in the Tobago population is low. METHODS: Admixture was estimated in a random sample of 220 men, from a population-based prostate cancer screening survey of 3,082 Tobago males, aged 40 to 79 years. We used a set of six autosomal markers with large allele frequency differences between the major ethnic populations involved in the admixture process, Europeans, Native Americans and West Africans. RESULTS: The ancestral proportions of Tobago population are estimated as 94.0+/-1.2% African, 4.6+/-3.4% European and 1.4+/-3.6% Native American. CONCLUSIONS: We conclude that Tobago Afro-Caribbean men are predominantly of West African ancestry, with minimal European and Native American admixture. The Tobago population, thus, may carry a higher burden of high-risk alleles of African origin for certain diseases than the more admixed African-American population. Conversely, this population may benefit from a higher prevalence of protective alleles of African origin.     

The genetic structure of populations from Haiti and Jamaica reflect divergent demographic histories

The West Indies represent an amalgamation of African, European and in some cases, East Asian sources, but the contributions from each ethnic group remain relatively unexplored from a genetic perspective. In the present study, we report, for the first time, allelic frequency data across the complete set of 15 autosomal STR loci for general collections from Haiti and Jamaica, which were subsequently used to examine the genetic diversity present in each island population. Our results indicate that although both Haiti and Jamaica display genetic affinities with the continental African collections, a stronger African signal is detected in Haiti than in Jamaica. Although only minimal contributions from non‐African sources were observed in Haiti, Jamaica displays genetic input from both European and East Asian sources, an admixture profile similar to other New World collections of African descent analyzed in this report. The divergent genetic signatures present in these populations allude to the different migratory events of Africans, Europeans, and East Asians into the New World. Am J Phys Anthropol 2010. © 2009 Wiley‐Liss, Inc.     

Molecular differentiation of Erwinia amylovora strains from North America and of two Asian pear pathogens by analyses of PFGE patterns and hrpN genes

In order to determine a possible genomic divergence of Erwinia amylovora'fruit tree' and raspberry strains from North America, several isolates were differentiated by pulsed-field gel electrophoresis (PFGE) analysis, the size of short DNA sequence repeats (SSRs) and the nucleotide and deduced amino acid sequences of their hrpN genes. By PFGE analysis European strains are highly related, whereas strains from North America were diverse and were further distinguished by the SSR numbers from plasmid pEA29. The E. amylovora strains from Europe showed identical HrpN sequences in contrast to the American isolates from fruit trees and raspberry. Those were related to each other, but distinguishable by their HrpN patterns. The Asian pear pathogens differed in HrpN among each other and from E. amylovora. Erwinia pyrifoliae isolates and the Erwinia strains from Japan were ordered via their HrpN sequences in agreement with the PFGE patterns. For all three pathogens, dendrograms from PFGE and sequence data indicate an evolutionary diversity within the species in spite of a genetic conservation for parts of the hrpN genes suggesting a long persistence of the Asian pear pathogens in Korea and Japan as well as of fire blight in North America. Some of the divergent American E. amylovora isolates share PFGE patterns with the relatively uniform European strains.     

Sex-specific genetic admixture of Mestizos, Amerindian Kichwas, and Afro-Ecuadorans from Ecuador

Three main ethnic groups live in the South American country of Ecuador: Mestizos, Amerindian natives, and African-derived populations, or Afro-Ecuadorans. Mestizos and Afro-Ecuadorans can be considered trihybrid populations containing genes originating in the Americas, Europe, and Africa, as is the case with equivalent populations in other Latin American countries. The proportion and the dynamics of the admixture process remain unknown. However, a certain sex asymmetry of the admixture process can be expected for historical reasons. We typed 11 Y-chromosome short tandem repeats (STRs) in these three ethnic groups to provide adequate allele and haplotype frequencies for forensic genetic purposes and to quantify admixture proportions in male lineages. In addition, a data set of 15 autosomal STRs in the same samples were reanalyzed for the same purpose. Contributions to Mestizo Y chromosomes were estimated to be 70% European, 28% Amerindian, and 2% African, whereas in autosomes the contributions were 19%, 73%, and 8%, respectively, which underlines the sexual asymmetry in mating, with Europeans contributing mostly males. European Y-chromosome haplotypes in Mestizos were similar to those in Spain. Moreover, about 10% of European Y chromosomes were found in the Amerindian Kichwa. As for Afro-Ecuadorans, their contributions to the male line are 44% African, 31% European, and 15% Native American; the last value is the highest percentage reported so far for an African-derived American group. Autosomal admixture was estimated as 56% African, 16% European, and 28% Amerindian.     

Genetic diversity in Arabidopsis thaliana L. Heynh. investigated by cleaved amplified polymorphic sequence (CAPS) and inter-simple sequence repeat (ISSR) markers

In this study, we investigated genetic diversity among 37 accessions in Arabidopsis thaliana from Eurasia, North Africa and North America using morphological traits and two polymerase chain reaction (PCR)-based marker systems: cleaved amplified polymorphic sequences (CAPS) and inter-simple sequence repeats (ISSR). Cluster analysis based on genetic similarities calculated from CAPS data grouped the accessions roughly according to their geographical origin: one large group contained accessions from Western, Northern and Southern Europe as well as North Africa, a second group consisted of Eastern European and Asian continental accessions. North American accessions were interspersed into these groups. Contrary to the CAPS analysis, the dendrogram obtained from the ISSR data did not reflect the geographical origin of the accessions, and the calculated genetic distances did not match the CAPS results. This could be attributable to an uneven genomic distribution of ISSR markers as substantiated by a database search for ISSR binding sites in A. thaliana genomic DNA sequence files, or to the ISSR's different mode of evolution. We recommend CAPS markers for diversity analysis in A. thaliana because a careful selection of markers can ascertain an even representation of the entire genome.     

Genetic diversity present within the near-complete mtDNA genome of 17 breeds of indigenous Chinese pigs

The genetic diversity present within the near-complete mitochondrial genome (15,982 bp) was determined from 17 indigenous Chinese pig breeds and 3 European breeds. Animals were selected from 17 Chinese breeds that reflect the large phenotypic diversity of Chinese pigs and represent each of the six breed types, which are grouped based on morphological characteristics. Analysis of nucleotide diversity confirmed a high level of divergence between animals of European versus Asian origin; however, much more limited variation was observed between the 17 indigenous Chinese breeds. Each had a unique haplotype, but the lowest pairwise sequence divergence was only 0.01 +/- 0.01%, observed between the Tongcheng and Yushan Black. Comparison of control region sequence diversity revealed the 17 Chinese breeds contain a lower average pairwise distance (0.61 +/- 0.19%) than a group of European commercial breeds (0.91 +/- 0.21%). The dendrogram constructed from the near-complete mtDNA sequences showed the Chinese sequences loosely clustering into two groups. Although some correspondence with geographic origin was present, notable differences between the dendrogram and the traditional pig breed grouping system were observed.     

Genetic Diversity and Structure of the Invasive Toxic Cyanobacterium <Emphasis Type="Italic">Cylindrospermopsis raciborskii</Emphasis>

Strains of the invasive toxic cyanobacteria Cylindrospermopsis raciborskii were genetically evaluated with four genetic markers encompassing in total 2.9 kb (16S rRNA, ITS longer spacer, ITS shorter spacer and rpoC1) to assess the phylogenetic relationships, genetic variation and population differentiation of the species across all five continents. The phylogenetic analysis showed that the C. raciborskii strains grouped into three well-supported distinct clusters: (I) European (II) African/American, and (III) Asian/Australian. The European group presented a high genetic similarity with the Asian and the Australian isolates than with the African and American isolates. Several Portuguese isolates were analyzed (n = 7) and revealed a low genetic differentiation with little geographical structure. The genetic distance among groups and phylogenetic relationships obtained in this study suggest that the recent invasion of C. raciborskii in Portuguese and other European temperate environments could have had its origin in the Asian and/or Australian continents.     

The Kintamani dog: genetic profile of an emerging breed from Bali, Indonesia

The Kintamani dog is an evolving breed indigenous to the Kintamani region of Bali. Kintamani dogs cohabitate with feral Bali street dogs, although folklore has the breed originating 600 years ago from a Chinese Chow Chow. The physical and personality characteristics of the Kintamani dog make it a popular pet for the Balinese, and efforts are currently under way to have the dog accepted by the Federation Cynologique Internationale as a recognized breed. To study the genetic background of the Kintamani dog, 31 highly polymorphic short tandem repeat markers were analyzed in Kintamani dogs, Bali street dogs, Australian dingoes, and nine American Kennel Club (AKC) recognized breeds of Asian or European origin. The Kintamani dog was identical to the Bali street dog at all but three loci. The Bali street dog and Kintamani dog were most closely aligned with the Australian dingo and distantly related to AKC recognized breeds of Asian but not European origin. Therefore, the Kintamani dog has evolved from Balinese feral dogs with little loss of genetic diversity.