Evaluation of genetic variability and mutation drift equilibrium of Banni buffalo using multi locus microsatellite markers

The present study was conducted to evaluate genetic diversity of Banni buffalo and its relationship/differentiation with Murrah using genotypic data on 24 heterologus bovine specific microsatellite marker loci. A total of 138 alleles were observed with a mean of 5.75 alleles/locus across two populations. The mean observed and expected heterozygosities were found to be 0.441 and 0.572 respectively in Banni buffaloes while it was 0.464 and 0.610 respectively in Murrah buffaloes. The average heterozygosity deficit was significantly positive with substantially higher values observed in Banni (22.3%) and Murrah (24%) buffalo populations. Banni buffalo population, when evaluated for mutation drift equilibrium revealed significant heterozygosity excess under IAM while no such excess was observed under SMM and TPM. The qualitative graphical test revealed a normal L-shaped distribution of allele frequencies indicating the absence of genetic bottleneck in Banni buffaloes. The mean estimates of F-statistics over all the loci were 0.376 for F_IT, 0.187 for F_ST and 0.232 for F_IS respectively. Analysis of molecular variance (AMOVA) revealed 18.95% of the total variation being explained by between breed differences while 14.36% of the variation explained differences between individuals within each breed. Genotype assignment test revealed distinct clustering of Banni and Murrah buffaloes. Genetic distance was estimated using three different methods, the results of which revealed considerable genetic differentiation between these two buffalo populations. The divergence time between Banni and Murrah buffaloes was estimated to be around 7286 years. The results of the present study may be helpful in decision making for conservation programs as Banni buffalo population is on decline.     

Genetic diversity and structure of the West Balkan Pramenka sheep types as revealed by microsatellite and mitochondrial DNA analysis

Several different phenotypes of the native Pramenka sheep have been developed in the Balkan region for different environmental and socio‐cultural conditions. Animals from seven West Balkan Pramenka sheep types were analysed for 15 microsatellite markers and for mitochondrial DNA (mtDNA) and the results were used to assess genetic variation within and among the types and to infer the genetic population structure of the Pramenka sheep. Mean expected heterozygosity and allelic richness over the microsatellite loci and sheep types were 0.78 and 7.9, respectively. A Bayesian statistical method for estimating hidden genetic structure suggested that a core of the largest panmictic population was formed by Serbian, Kosovan, Bosnian, Montenegrin and Albanian types, while Croatian and Macedonian types comprised two other main populations, respectively. Mitochondrial DNA analysis revealed two mtDNA haplogroups in the Pramenka sheep, B and A, with a frequency of 93.7% and 6.3%, respectively. A total of 60 mtDNA haplotypes were found in 64 animals sequenced, and the mean nucleotide and haplotypic diversities over the types were 0.013 and 0.945, respectively. Molecular analysis suggests that the West Balkan Pramenka sheep types have their origins in two distinct maternal lineages of domestic sheep and different Pramenka phenotypes tend to form few panmictic populations. The Pramenka sheep represents a valuable resource of genetic diversity in sheep.     

Genetic diversity of Swiss sheep breeds in the focus of conservation research

There is constant pressure to improve evaluation of animal genetic resources in order to prevent their erosion. Maintaining the integrity of livestock species as well as their genetic diversity is of paramount interest for long-term agricultural policies. One major use of DNA techniques in conservation is to reveal genetic diversity within and between populations. Forty-one microsatellites were analysed to assess genetic diversity in nine Swiss sheep breeds and to measure the loss of the overall diversity when one breed would become extinct. The expected heterozygosities varied from 0.65 to 0.74 and 10.8% of the total genetic diversity can be explained by the variation among breeds. Based on the proportion of shared alleles, each of the nine breeds were clearly defined in their own cluster in the neighbour-joining tree describing the relationships among the breeds. Bayesian clustering methods assign individuals to groups based on their genetic similarity and infer the number of populations. In STRUCTURE, this approach pooled the Valais Blacknose and the Valais Red. With BAPS method the two Valais sheep breeds could be separated. Caballero & Toro approach (2002) was used to calculate the loss or gain of genetic diversity when each of the breeds would be removed from the set. The changes in diversity based on between-breed variation ranged from −12.2% (Valais Blacknose) to 0% (Swiss Black Brown Mountain and Mirror Sheep); based on within-breed diversity the removal of a breed could also produce an increase in diversity (−0.6% to + 0.6%). Allelic richness ranged from 4.9 (Valais Red) to 6.7 (Brown Headed Meat sheep and Red Engadine Sheep). Breed conservation decisions cannot be limited to genetic diversity alone. In Switzerland, conservation goals are embedded in the desire to carry the cultural legacy over to future generations.     

微卫星分子标记分析四川绵羊群体遗传多样性

为探究四川省6个绵羊群体的遗传多样性,实验应用12个微卫星标记计算基因频率、有效等位基因数、杂合度及多态信息含量来评估群体内遗传多样度,通过遗传距离聚类图、群体结构推测图、主成分分析及群体间分子方差分析来评估群体间遗传关系。结果表明:6个绵羊群体在12个微卫星位点的平均有效等位基因数为3.006~3.176,平均多态信息含量变化为0.559~0.612,平均期望遗传杂合度为0.610~0.670;6个绵羊群体间的遗传关系与地理分布情况及育成史实不完全一致,但遗传距离聚类图、群体结构推测图和主成分分析结果均显示,6个绵羊群体中布拖黑绵羊类群与贾洛绵羊类群遗传关系更近;6个绵羊群体间方差组分F统计量结果为0.112 39,处于中度分化水平。     

Genetic analysis of Mexican Criollo cattle populations

The objective of this study was to evaluate the genetic structure of Mexican Criollo cattle populations using microsatellite genetic markers. DNA samples were collected from 168 animals from four Mexican Criollo cattle populations, geographically isolated in remote areas of Sierra Madre Occidental (West Highlands). Also were included samples from two breeds with Iberian origin: the fighting bull (n = 24) and the milking central American Criollo (n = 24) and one Asiatic breed: Guzerat (n = 32). Genetic analysis consisted of the estimation of the genetic diversity in each population by the allele number and the average expected heterozygosity found in nine microsatellite loci. Furthermore, genetic relationships among the populations were defined by their genetic distances. Our data shows that Mexican cattle populations have a relatively high level of genetic diversity based either on the mean number of alleles (10.2-13.6) and on the expected heterozygosity (0.71-0.85). The degree of observed homozygosity within the Criollo populations was remarkable and probably caused by inbreeding (reduced effective population size) possibly due to reproductive structure within populations. Our data shows that considerable genetic differentiation has been occurred among the Criollo cattle populations in different regions of Mexico.     

The biodiversity and genetic structure of Balearic sheep breeds

The Balearic sheep breeds, Mallorquina, Menorquina, Roja Mallorquina, Ibicenca and one possible new genetic group, Formentera, constitute a unique genetic resource in the Mediterranean farming landscape, displaying high genetic diversity levels and being well differentiated among themselves and with respect to the continental sheep breeds. We used a microsatellite panel of markers to study genetic diversity and relationships with other Spanish breeds. The results reported in this study have important implications for the use, conservation and breeding of Balearic sheep stocks. A mean number of 7.59 alleles was found among the Balearic sheep breeds for the microsatellites scored. The whole mean value of observed heterozygosity amounted to 0.62, whereas the expected heterozygosity value was 0.69, suggesting the presence of a great degree of genetic variability, although a significant deficit of heterozygotes was detected for some markers. Genetic distance estimates showed that Balearic sheep are differentiated from the other Spanish breeds and in particular, from the Merino type. The Ibicenca breed showed the highest distance value from other breeds. The neighbour‐net method of analysis clustered the Roja Mallorquina, Menorquina and Mallorquina breeds. The Structure results clearly demonstrated the genetic differentiation among the four Balearic sheep breeds, with the Ibicenca and Formentera races joined, with slight migration among them. Few external genetic influences from the Spanish mainland breeds were detected.     

茶花鸡种群遗传结构分析及其保种措施的探讨

利用14个微卫星标记对云南茶花鸡12个家系的等位基因频率、平均基因杂合度、平均多态信息含量以及家系间的亲缘关系进行了分析。结果表明:共检测到99个等位基因,每个位点的等位基因分布并不均匀,再对12个家系进行分析,将其聚为3类,一类为Z-1,Z-2,Z-3,Z-4,Z-5,Z-6,B-1,一类为Z-7,Z-8,Z-9,Z-10,矮脚系B-2自成一类,这表明了家系间的遗传相似性,同时我们对特殊的矮脚系B-2进行了相关的探讨,最后我们提出了对茶花鸡保种的相关建议。     

4个地方绵羊品种系统发生关系的微卫星分析

试验旨在研究地方绵羊品种的遗传变异,为种质资源评价、保护和利用提供理论数据。利用5个微卫星标记分析4个地方绵羊品种的遗传多样性,根据等位基因组成及频率进行群体遗传统计分析;基于品种间标准遗传距离(Ds)和Nei氏遗传距离,分别构建UPGMA系统发生树。4个地方绵羊品种共检测到70个等位基因,各位点等位基因数(Na)在10~18之间;4个地方绵羊品种平均有效等位基因数(Ne)为3.81~5.68个,平均多态信息含量(PIC)为0.6152~0.7373,平均遗传杂合度(H)为0.6711~0.7820;4个地方绵羊品种间遗传分化系数为0.0847,标准遗传距离(Ds)和Nei氏遗传距离晋中绵羊与乌珠穆沁羊为最大(0.5775、0.6126),小尾寒羊与乌珠穆沁羊为最小(0.1542、0.1955),首先小尾寒羊与乌珠穆沁羊聚为一类,晋中绵羊与广灵大尾羊聚为另一类,然后两类聚在一起形成一大类。结果表明,4个地方绵羊品种遗传变异大、多样性丰富;品种间遗传分化小,但小尾寒羊和乌珠穆沁羊与晋中绵羊和广灵大尾羊间已有明显分化。选择的5个微卫星座位均为高度多态位点,可作为有效遗传标记用于绵羊品种遗传多样性和系统发生关系分析。各地方绵羊品种分子聚类关系与其形成史、分化及地理分布基本一致。     

中国地方绵羊群体TYRP1基因遗传变异研究

本研究旨在了解酪氨酸酶相关蛋白1（tyrosinase related protein 1，TYRP1）基因在中国地方绵羊群体内的遗传变异，以及TYRP1基因突变与不同毛色表型绵羊群体的相关性。通过直接测序法和PCR-RFLP技术对10个中国地方绵羊群体进行单核苷酸多态性（SNP）检测，利用Beagle、PLINK和POPGENE等软件对突变位点数据进行单倍型构建、连锁不平衡分析和遗传变异研究。突变位点检测结果表明，在绵羊TYRP1基因内识别了13个SNPs，其中位于TYRP1基因外显子上的10个SNPs位点，除个别位点在大尾寒羊、中国美利奴羊和岷县黑裘皮羊中没有发生突变外，其他突变位点在所有绵羊品种中均出现不同程度变异，说明中国地方绵羊群体具有较高的遗传多样性。单倍型分析结果表明，所有样本中共有42个单倍型，优势单倍型0000000000（245/918）、0100000001（91/918）在所有绵羊群体中均存在，除单倍型0101100000（93/918）在中国美利奴羊中没有出现，单倍型0001000001（69/918）在岷县黑裘皮羊、哈萨克羊群体中没有出现外，在其他群体中均存在。连锁分析结果表明，10个SNPs在所有样本中均存在2个连锁模块。群体遗传变异分析表明，中国地方绵羊群体具有较高水平的群体内遗传变异，各绵羊品种间存在明显的遗传分化模式，且各品种遗传关系与其品种传统分类结果基本一致。本研究为进一步研究TYRP1基因对绵羊毛色遗传性状的影响提供了参考依据。     

Genetic diversity and differentiation of Mongolian and Russian yak populations

In this study we examined the genetic diversity of yak populations in the northernmost part of their current global distribution. Five Mongolian and one Russian yak populations as well as one Chinese yak population from the Qinghai–Tibetan Plateau, the putative centre of yak domestication, were analysed with 15 microsatellite loci to determine the level of genetic variation within populations as well as the genetic differentiation and relationship between populations. A total of 116 microsatellite alleles were identified. The mean number of alleles per locus (MNA) across populations was 7.73 ± 1.98 and the mean expected heterozygosity (H_E) was 0.696 ± 0.026. The relative magnitude of gene differentiation (F_ST) among populations was 4.1%, and all genetic differentiations (F_ST) between populations were significant (p < 0.001). A significant inbreeding effect (F_IS) was detected in the Hovsgol yak (p < 0.01). There was no indication of a recent bottleneck in any of the populations studied. The results showed that yak populations in Mongolia and Russia have maintained high genetic diversity within populations and a low, although significant, genetic differentiation between populations. Both phylogenetic and principal component analyses support a close genetic relationship between the Gobi Altai, south Gobi and north Hangai populations, and between the Hovsgol and Buryatia populations respectively. Our results indicate that these yak populations should be considered as distinct genetic entities in respect of conservation and breeding programmes.     

A preliminary study of the genetic diversity of Xinjiang Tarim red deer (Cervus elaphus yarkandensis) using the microsatellite DNA method.

To evaluate the genetic diversity of the Xinjiang Tarim red deer (Cervus elaphus yarkandensis) population, we analyzed the frequencies of microsatellite alleles. Samples were collected from 3 isolated populations in Xaya, Lopnur and Qarqan of Xinjiang. Although 10 microsatellite loci were examined, alleles of 133 to 190 base-pairs were detected for only 3 loci: BM5004, BM4208 and BM888. The average observed multilocus heterozygosity was 0.08 +/- 0.04 for the Xaya, 0 for the Lopnur, and 0.17 +/- 0.08 for the Qarqan population. The average heterozygosity of all populations was 0.08 +/- 0.02. The observed heterozygosities were significantly lower than the expected values. The present results suggest that the bottleneck effect has occurred in the populations of the Xinjiang Tarim red deer.     

闽西南黑兔遗传多样性的微卫星标记分析

利用微卫星标记技术,选用16个微卫星位点对60只闽西南黑兔群体遗传多态性和遗传结构进行分析。结果表明,在所检测的闽西南黑兔群体中,16个微卫星位点共检测到了75个等位基因,各位点的等位基因数在3～7之间,平均等位基因数为4.688个,平均有效等位基因数为3.443。各位点平均基因频率取样方差V（pij）为5.7546×10-3。16个微卫星位点平均观察杂合度HO为0.764,范围在0.200～1.000之间,平均期望杂合度He 0.685,其范围在0.410～0.811之间,各位点多态信息含量（PIC）变动范围为0.359～0.776,平均PIC为0.629,其中有13个位点处于高度多态（PIC〉0.5）,16个微卫星位点的平均固定指数（F）为-0.115。在所检测的16个微卫星位点上,经x2平衡检验,闽西南黑兔群体偏离Hardy～Weinberg程度不大。     

Assessment of genetic diversity and conservation priority of Omani local chickens using microsatellite markers

Designing strategies for conservation and improvement livestock should be based on assessment of genetic characteristics of populations under consideration. In Oman, conservation programs for local livestock breeds have been started. The current study assessed the genetic diversity and conservation potential of local chickens from Oman. Twenty-nine microsatellite markers were analyzed in 158 birds from six agroecological zones: Batinah, Dhofar, North Hajar, East Hajar, Musandam, and East Coast. Overall, a total of 217 alleles were observed. Across populations, the average number of alleles per locus was 7.48 and ranged from 2 (MCW98 and MCW103) to 20 (LEI094). The mean expected heterozygosity (H _E) was 0.62. Average fixation index among populations (F _ST) was 0.034, indicating low population differentiation, while the mean global deficit of heterozygotes across populations (F _IT) was 0.159. Based on Nei’s genetic distance, a neighbor-joining tree was constructed for the populations, which clearly identified the Dhofar population as the most distant one of the Omani chicken populations. The analysis of conservation priorities identified Dhofar and Musandam populations as the ones that largely contribute to the maximal genetic diversity of the Omani chicken gene pool.     

洼地绵羊MHC-DRB1基因PCR-RFLP多态性分析

为了探讨洼地绵羊MHC-DRB1基因的多态性,采用套式PCR扩增82只洼地绵羊的MHC-DRB1基因第2外显子,其296 bp扩增产物经Sac Ⅰ、Hae Ⅲ限制性内切酶酶切后进行RFLP多态性分析.结果表明,洼地绵羊的MHC-DRB1基因外显子2在Sac Ⅰ、Hae Ⅲ的酶切位点存在多态性,测序发现,这些酶切位点分别...     

Genetic diversity and population structure of the endangered Namaqua Afrikaner sheep

The Namaqua Afrikaner is an endangered sheep breed indigenous to South Africa, primarily used in smallholder farming systems. Genetic characterization is essential for the breed’s conservation and utilization. In this study, a genetic characterization was performed on 144 Namaqua Afrikaner sheep kept at the Karakul Experimental Station (KES), Carnarvon Experimental Station (CES), and a private farm Welgeluk (WGK) using 22 microsatellite markers. The mean number of alleles observed was low (3.7 for KES, 3.9 for CES, and 4.2 for WGK). Expected heterozygosity values across loci ranged between 46 % for WGK, 48 % for KES, and 55 % for CES, indicating low to moderate genetic variation. The analysis of molecular variance revealed that 89.5 % of the genetic variation was due to differences within populations. The population structure confirmed the differentiation of three clusters with high relationships between the CES and WGK populations. In the population structure comparison with Pedi and South African Mutton Merino sheep, limited hybridization between the Namaqua Afrikaner sheep and both of these breeds was observed. The results of this study will serve as a reference for genetic management and conservation of Namaqua Afrikaner sheep.     

江苏省野生及家养中华蜜蜂微卫星DNA遗传多样性分析

利用8对微卫星标记对江苏省野生及家养中华蜜蜂群体遗传多样性进行分析，评估群体内的遗传变异和群体间的遗传分化，结果表明，共检测到31个等位基因，每个位点的等位基因数从1～7不等，平均等位基因数为3.875；所有位点平均的期望杂合度和PIC值分别为0.4424和0.4054。野生及家养中华蜜蜂群体8个微卫星位点平均有效等位基因数分别为3.83和4.17，平均基因杂合度为0.0778和0.0993，两个群体均表现出较低的群体杂合度和遗传多样性。群体分化系数为4.9%（P<0.001），两个群体的Reynolds’遗传距离和Nm值分别为0.05024和4.852。江苏省野生及家养中华蜜蜂群体均表现出较低的群体杂合度和遗传多样性水平，且有相互交流的迹象。     

Romilly Hills羊遗传多样性的微卫星分析

利用 1 0个微卫星标记对新疆兵团农七师从南非引进的罗米丽 (RomillyHills)绵羊和中国美利奴羊 (新疆军垦型 )遗传多样性进行了检测。统计了两群体的等位基因组成、平均有效等位基因数 (E)和平均基因纯合率 ,利用等位基因频率计算出两群体的平均遗传杂合度 (h)、多态信息含量 (PIC)。结果表明 1 0个微卫星位点在RomillyHills羊、中国美利奴羊群体中的平均多态信息含量分别为 0 5952和 0 5859,除BM1 82 4、MAF65外均为高度多态 ,可作为有效的遗传标记用于两品种绵羊遗传多样性分析 ;RomillyHills羊的群体遗传变异大于中国美利奴羊 ,其遗传多样性相对丰富 ,有较大的选育潜力。     

盘羊及其杂交后代微卫星遗传多样性分析

为了更好地了解盘羊及其杂交后代（盘羊♂×欧拉羊♀）的遗传信息,为盘羊遗传资源评价及欧拉羊的复壮改良提供理论依据。本试验选取24对微卫星引物,应用PCR扩增和毛细管电泳的方法对24只盘羊和24只杂交羊个体进行遗传多样性分析。结果显示,在24只盘羊中,24个微卫星位点上共检测到167个等位基因,平均等位基因数目为6.9583,平均有效等位基因数为3.3665,平均观测杂合度为0.4497,平均期望杂合度为0.6779,平均多态信息含量为0.6265,其中,等位基因数目最多的是位点MAF70,有效等位基因数目、期望杂合度、多态信息含量最高的是位点OarFCB193,观测杂合度最高的是位点ILSTS11;在24只杂交羊中,24个微卫星位点上共检测到154个等位基因,平均等位基因数目为6.4166,平均有效等位基因数为3.4061,平均观测杂合度为0.4566,平均期望杂合度为0.6751,平均多态信息含量为0.6265,其中,等位基因数目、有效等位基因数目、期望杂合度、多态信息含量最高的是位点MAF70,观测杂合度最高的是位点OarJMP58。从遗传学角度得出,盘羊和杂交羊遗传指标结果相近,试验所得数据可用于盘羊遗传资源评价及欧拉羊的复壮改良。     

利用微卫星标记分析不同保种场的保种效果

分别采用23对微卫星引物分析了我国两个地方品种北京油鸡和北京鸭在不同保种场的保种效果。检测了北京油鸡和北京鸭共计240个个体的基因型,通过计算等位基因数量、遗传杂合度(H)、多态信息含量(PIC)、F统计量和Nei氏遗传距离分析了北京油鸡和北京鸭群体内与群体间的变异,比较了两个品种不同保种场的保种效果。在所检测的4个群体中,各群体均有较高的多态性,其杂合度均超过了0.5,除微卫星座位APL82(北京鸭Ⅱ)为纯合位点外,各位点等位基因数量为2~16个。结果表明,4个保种场均较好地保存了这些品种的遗传多样性,但同一品种保种场间保种群体已经发生了分化。     

新麦草遗传多样性等位酶分析

采用不连续系统的聚丙烯酰胺垂直板凝胶电泳(VPAGE)对新疆新麦草的5个天然居群和1个栽培种遗传多样性和居群结构进行了分析.测定的6个酶系统中,确定了9个等位酶位点,多态位点百分率平均值为90.48%,平均等位基因数为2.920 7,平均预期杂合值为0.542 7.总的基因多样性中,86%存在于居群内,14%来自居群间.聚类分析以遗传距离D=0.14为分界线将6份材料明显地分为2组.研究表明,新麦草具有丰富的遗传多样性,其多样性可能与生境、人工驯化、风媒异交等因素有关.