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At least 721 records · Page 40Linked to original sources
PubMed2005

Genetic structure of pig breeds from Korea and China using microsatellite loci analysis.

To understand molecular genetic characteristics of Korean pigs, the genetic relationships of nine pig breeds including two Korean pigs (Korean native pig and Korean wild pig), three Chinese pigs (Min pig, Xiang pig, and Wuzhishan pig), and four European breeds (Berkshire, Duroc, Landrace, and Yorkshire) were characterized from a 16-microsatellite loci analysis. The mean heterozygosity within breeds ranged from 0.494 to 0.703. Across multiple loci, significant deviation from Hardy-Weinberg equilibrium was observed in most pig breeds, except for two Chinese pigs (Min pig and Wuzhishan pig). This deviation was in the direction of heterozygote deficit. Across population loci, 36 of 144 significantly deviated (P < 0.05) from Hardy-Weinberg equilibrium. The mean FST, a measure of genetic divergence among subpopulations, of all loci indicated that 26.1% of total variation could be attributed to the breed difference. Relationship trees based on the Nei's DA genetic distance and scatter diagram from principal component analysis consistently displayed pronounced genetic differentiation among the Korean wild pig, Xiang pig, and Wuzhishan pig. Individual assignment test using a Bayesian method showed 100% success in assigning Korean and Chinese individual pigs into their correct breeds of origin and 100% exclusion success from all alternative reference populations at P < 0.001. These findings indicate that the Korean native pig has been experiencing progressive interbreeding with Western pig breeds after originating from a North China pig breed with a black coat color. Considering the close genetic relationship of Korean pigs to the Western breeds such as Berkshire and Landrace, our findings can be used as valuable genetic information for the preservation and further genetic improvement of the Korean native pig.

Alleles↗
PubMed2003

[Population-genetic structure of Chuvashia (from data on eight DNA loci in the nuclear genome)].

Population-genetic study of indigenous populations representing three ethnic Chuvash group: highland (Cheboksarsk and Morgaush district), lowland (Kanash district) and mid-lowland (Marposad district). Eight polymorphic DNA loci of the nuclear genome (VNTR/PAH, STR/PAH, VNTR/ApoB, VNTR/DAT1, APF, VNTR/eNOS, IVS6aGATT, and KM.19/PstI) were examined in the population of each district. For each of the four population, we estimated the allele and genotype frequency distributions at each polymorphic system, heterozygosities HS and between-population differences FST. In the combined Chuvash sample, HS = 0.464 and FST = 0.006. Loci VNTR(DAT) and VNTR(ApoB) showed highest between-population differentiation (0.009 < or = FST < or = 0.012), and loci IVS6aGATT, APF, VNTR/eNOS, and D7S23 (KM.19), lowest differentiation (0.001 < or = FST < or = 0.003). Analysis of genetic distances revealed somewhat higher genetic similarity between the Cheboksarsk and Morgaush populations belonging to the highland Chuvash group, whereas the highland Chuvash population from the Marposad district, which belong to the mid-lowland group, was more distant from the former populations.

Base Sequence↗
PubMed1999

Reproductive mode and population genetic structure of the cereal aphid Sitobion avenae studied using phenotypic and microsatellite markers.

As French populations of the aphid Sitobion avenae exhibit a range of reproductive modes, this species provides a good opportunity for studying the evolution of breeding system variation. The present analysis combined ecological and genetic investigations into the spatial distribution of variation in reproductive mode. Reproductive mode was characterized in 277 lineages of S. avenae from France, and these aphids were scored for five microsatellite loci. The analyses revealed strong geographical partitioning of breeding systems, with obligate asexuals mostly restricted to the south of France, while lineages producing sexual forms were more common in the north. Contrary to what might be anticipated for organisms with frequent parthenogenesis, there was substantial genic and genotypic diversity, even in the obligately asexual lineages. More than 120 different genotypes were detected among the 277 aphid lineages, with an average of 5.9 alleles per locus (range four to 16) and heterozygosity of 56.7%. As with previous studies of allozyme variation in aphids, most loci showed heterozygote deficits, and disequilibrium was common among allelic variants at different loci, even after removal of replicate copies of genotypes that might have been derived through clonal reproduction. Our results suggest that selection is important in structuring reproductive systems and genetic variation in French S. avenae. Canonical correspondence analysis was employed to examine the associations between genotypic and phenotypic variables, enabling the identification of alleles correlated with life-history traits.

Animals↗
PubMedDate not supplied

[Genetic structure of crucian carp (Cypriniformes, Cyprinidae, Carassius L. 1758) populations of middle-Dnieper basin].

Comparative analysis of Middle Dnieper crucian carp's population structure was made by means of biochemical gene marking, cytometry and biological analysis. As a result the structure was found, which may by expounded like association of the genetically related species and forms. This association consists of diploid C. auratus (which predominates in population), C. carassius (which was found in the some of north-eastern reservoirs only) and triploid C. gibelio. In Ukraine the homogeneous populations of C. gibelio can be found on the north-east of Eastern Ukraine only. Though some of individuals maybe present with diploid C. auratus. Besides were found hybrid form: diploid C. auratus-C. carassius and presumably tetraploid C. auratus-C. gibelio and C. gibelio-C. carassius. However in the tetraploid's spectra were absent a number of specific alleles, that marking C. species-one of the parental species of triploid C. gibelio. Therefore presumptive tetraploids have not difference from C. auratus and diploid C. auratus-C. carassius on the gene markers level. Nevertheless they are neatly diagnose by the erythrocytes which have good difference and are bigger then diploid species erythrocytes in 40% (C. auratus-C. gibelio) and 100% (C. gibelio-C. carassius).

Animals↗
PubMed1982

Genetic structure and origin of t haplotypes of mice, analyzed with H-2 cDNA probes.

We investigated the genetic organization and evolutionary origin of t chromosomes of mice by examining the restriction fragment patterns of DNA from t haplotypes and normal chromosomes with cDNA probes to H-2 class I genes. On genomic DNA blots, the restriction fragments containing H-2-related sequences were highly variable among different inbred strains of mice, whereas they were very similar among different t haplotypes even when the t haplotypes carried serologically different H-2 haplotypes. These observations suggest that all t haplotypes have a common origin and are not products of independent mutational events. We also mapped the position of several restriction fragments characteristic of t DNA by using a battery of recombinant t haplotypes, defined with respect to their t-lethal factors and H-2 haplotypes. We thus show that restriction fragments containing H-2-related sequences map to the left of the H-2 class I genes in t chromosomes, a region in which the tw32 b-lethal factor also maps. The cloning of these fragments can be expected to provide an entry for the structural analysis of t DNA.

Animals↗
PubMed1997

Analysis of population genetic structure and variability using RAPD markers in the endemic and endangered Limonium dufourii (Plumbaginaceae).

Limonium dufourii (Plumbaginaceae) is a triploid species, with apomictic reproduction, endemic to the east mediterranean coast of Spain, where it is present in only six populations with a few individuals in most of them. L. dufourii is included in the Red List of Endangered Species by the IUCN. Genetic variation and population structure in this species has been studied using RAPDs. Twelve different primers provided 124 reliable bands of which 33 were polymorphic among the 165 individuals analysed. Those polymorphic bands were able to define 44 different patterns, of which all but six were present in only one population. Several methods for statistical evaluation have been used for intra- and interpopulation analysis of genetic variability. Relationships among patterns have led to the identification of four main clusters. Two of them show a perfect correspondence to the population of origin of those individuals that present them (Cullera and Torreblanca), and the other two (Groups A and B) include patterns found in individuals coexisting in the same populations (Marjal del Moro populations) and in El Saler. Most of the variation found in this species is due to differences among populations as shown by the analysis of molecular variance. This agrees with the expectation for an apomictic species such as L. dufourii. The analysis of homogeneity of variance shows that substantial differences in the amount of genetic variability present in the six populations exist. These results have been used to understand the evolutionary and demographic history of L. dufourii, which is a requisite in order to establish efficient conservation measures for this species.

DNA Primers↗
PubMed2006

Genetic structure and phylogenetic relationships of the Polish Heavy horse.

In this study a wide range of genetic markers (12 microsatellites, 7 blood-group loci, 10 blood-protein loci) and mitochondrial DNA (mtDNA) were used to assess genetic diversity in Polish Heavy horses. Three random samples were sequenced for 421 bp of the mitochondrial D-loop region, but no clear phylogenetic patterns were seen in mtDNA variation. Both heterozygosity and diversity levels are fairly high in Polish Heavy horses. In phylogenetic analysis the draught horses form a distinct cluster that pairs with the true pony breeds. Within this 'cold-blooded' group, the Polish Heavy Horse clusters most closely with the Posavina breed from Croatia and the Breton breed from France. From the standpoint of genetic conservation, the Polish Heavy Horse does not appear to be in jeopardy.

Animals↗
PubMed2003

Genetic structure along a gaseous organic pollution gradient: a case study with Poa annua L.

The population genetic composition of Poa annua L. was studied by starch electrophoresis along a transect running NE from an organic reagents factory at Shanghai, China. Five enzyme systems were stained. We have reached the following preliminary conclusions: (1). Organic pollution has dramatically changed genotypic frequencies at some loci of Poa annua populations. At polluted sites, significant deviations from Hardy-Weinberg equilibrium were observed on loci Sod-1 and Me due to the excess of heterozygote. Especially in the two nearest sites to pollution source, all the individuals were heterozygous at locus Sod-1. The data suggests that heterozygotes were more tolerant to organic pollution than homozygotes, indicating the fitness superiority of heterozygotes. (2). A tendency towards clinal changes of allele frequencies was found at some polymorphic loci. Frequencies of the common alleles at loci Sod-1, Me and Fe-1 increased as the distance to the pollution source increased. (3). The effective number of alleles per locus, and the observed and expected heterozygosity were much higher in the pollution series than in the clear control site (Botanic Park population), but genetic multiplicity (number of alleles per locus) was lower than for the control. (4). Most genetic variability was found within populations, and only 2.56% were among populations of the polluted series. However, 9.48% of the total genetic variation occurred among populations when including the Botanic Park population. The genetic identity between populations of the pollution series (0.9869-1.0000, mean 0.9941) was higher than those between the pollution series and the Botanic Park population. UPGMA divided the five populations into two groups. One contained the four polluted populations, and the other only contained the Botanic Park population.

Air Pollutants↗
PubMed1996

A hierarchical analysis of population genetic structure in Rhizobium leguminosarum bv. trifolii.

Little is known about the population processes that shape the genetic diversity in natural populations of rhizobia. A sample of 912 Rhizobium leguminosarum biovar trifolii isolates were collected from naturalized red clover populations (Trifolium pratense) and analysed for 15 allozyme loci to determine the levels and distribution of genetic diversity. Hierarchical analyses compared different sampling levels, geographical separation, and temporal separation. Total genetic diversity across all isolates was H = 0.426, with 57.6% of the total diversity found among isolates obtained from individual red clover plants. Relatively low genetic differentiation among populations and high differentiation among plants within populations was observed; this suggests that gene flow and founder effect act differently at geographical and local scales. Significant differences were observed in (i) allele frequencies among populations and among plants within populations, and (ii) the frequency distribution of the most widespread and the most abundant strains. When multilocus linkage disequilibrium was calculated, significant levels of disequilibrium were observed in the total sample and in three of the eight populations.

Alleles↗
PubMed2000

Allozyme diversity and population genetic structure of Pinus densata Master in northwestern Yunnan, China.

We investigated the levels and patterns of genetic diversity of Pinus densata Master in Yunnan. Horizontal starch-gel electrophoresis was performed on macrogametophytes collected from nine populations in northwestern Yunnan, China. Compared with other gymnosperm species, P. densata has higher mean values for all measures of genetic diversity. Allozyme polymorphism (0.99 criterion) was 97.0% and 71.4% at the species and population levels, respectively. The average number of alleles per locus was 3.1 and 2.0 at the species and population levels. Mean expected heterozygosity was substantially higher in P. densata than average values investigated for other gymnosperms both at the population (Hep = 0.174 +/- 0.031) and at the species (Hes = 0.190) levels. Of the total genetic variation, less than 12% was partitioned among populations (GST = 0.112). Our allozyme survey supports the suggestion that the observed higher diversity in P. densata may be attributed partly to its hybrid origin between two genetically distinct species, P. yunnanensis and P. tabulaeformis. In addition, we suggest that introgression would give rise to the increase in genetic diversity occurring in P. densata.

Alleles↗
PubMed2005

Genetic variability and genetic structure of wild and semi-domestic populations of tasar silkworm (Antheraea mylitta ) ecorace Daba as revealed through ISSR markers.

The genetic diversity in the wild and semi-domestic populations of Daba ecorace of Antheraea mylitta was studied to ascertain the distribution of variability within and among populations of semi-domestic bivoltine (DB), trivoltine (DT) and nature grown wild populations (DN) with inter-simple sequence repeat (ISSR) markers. A total of 138 markers were produced among 56 individuals of the three populations, of which 98% were polymorphic. For the individual populations, the percentage polymorphism was 58.69, 52.9 and 77.54 for DB, DT and DN, respectively. Average number of observed (1.791+/- 0.408) and effective alleles (1.389+/-0.348) was also high in the wild populations in comparison to the bivoltine and trivoltine semi-domestic populations. Genetic diversity (H(t)) in DB, DT and DN was 0.180+/- 0.033, 0.153+/- 0.032 and 0.235+/- 0.033, respectively and within-population genetic diversity (H(s)) ranged from 0.166 to 0.259 with a mean of 0.189. Mean gene differentiation (G(ST)) was found to be 0.25. Shanon's diversity index was 0.278, 0.237 and 0.361 for DB, DT and DN and overall it was 0.391. Gene flow (N(m)) among the populations was 1.509. The dendrogram produced by UPGMA with Dice's genetic distance matrices resulted in the formation of three major clusters separating the three populations. Considerable intra- and inter-population variability is found in all three populations. The population structure analysis further suggests that the semi-domestic populations of Daba ecorace are at the threshold of differentiating themselves. The high genetic variability present within wild Daba population of A. mylitta is of much importance for conservation as well as utilization in systematic breeding program.

Alleles↗
PubMed1999

Genetic structure in three haploid peat mosses (Sphagnum)

Over the past 20 years, studies have revealed levels of genetic variation in bryophytes that are similar to those found in vascular plants. This has led many to question the traditional view of bryophyte evolution, which holds that these organisms have a low evolutionary rate. RAPD and isozyme analyses were used to measure genetic variation in 18 populations of several Sphagnum taxa, with special emphasis on the bisexual S. lindbergii and the unisexual S. angustifolium, S. fallax and S. isoviitae. Both types of markers were found to be selectively neutral. A test of population differentiation showed no significant divergence between S. fallax and S. isoviitae growing in sympatry; these taxa were therefore treated as conspecific. Only S. angustifolium had polymorphic isozyme loci. The highest genetic variation in RAPD loci was found in S. angustifolium; the lowest in S. lindbergii. There seemed to be a high turnover rate of individuals in S. angustifolium populations. Populations of S. fallax coll. were strongly differentiated for RAPD markers, whereas S. angustifolium populations were only weakly differentiated for any marker, even for populations from different continents. Populations of S. lindbergii were not differentiated at all. Most studied populations did not fit the 'Conocephalum - Plagiomnium' model of bryophyte population structure. The observed patterns could best be explained by assuming a low evolutionary rate, at least in S. angustifolium, meaning that high levels of molecular variability seem not to be incompatible with slow evolution.

Journal Article↗
PubMedDate not supplied

New data on the genetic structure of the population of Sicily: analysis of the Alia population (Palermo, Italy).

The distribution of 13 genetic markers (AB0, Rh, ACP, ADA, AK, ESD, GLO, PGD, PGMl, SOD, GC, TF, and PI) were studied in a sample from the Alia population of Sicily, Italy. A total of 34 alleles were detected. In comparison with other Sicilian populations, Alia always appeared genetically distinctive, either in terms of overall genetic diversity or for the number of unique alleles present. The results are consistent with previous studies that show no genetic uniformity within the island. More specifically, the data support the genetic divergence of the eastern and western halves of the island and highlight genetic boundaries that run through Sicily and divide it into three distinct areas.

Alleles↗
PubMed2005

Genetic structure of an endangered Portuguese semiferal pony breed, the Garrano.

The present study intends to survey the genetic variability of an endangered semiferal Portuguese native pony breed, the Garrano. Thirteen microsatellite markers were examined in 277 animals born in 1998, belonging to eight subpopulations corresponding to eight northern Portuguese geographic regions. Mean heterozygosity (H(o)) in the Garrano breed was 0.732, ranging from 0.531 to 0.857 across subpopulations. Allelic frequencies and diversity differed significantly between regions, suggesting the existence of genetic differentiation within the breed confirmed by the population differentiation estimator F(ST). Allele sharing genetic distance (Dps) was used to determine the relationship between the analyzed subpopulations, some of which are diverging significantly from the others. Relationships among six Iberian horse breeds (including the Garrano) were assessed through the restricted maximum likelihood method, which clusters the Garrano with another Celtic pony, the Spanish Asturcon, traditionally bred in geographical continuity with the Garrano. Results reveal a statistically significant deficit of heterozygotes within the Garrano breed (F(IT) = 0.031, p < 0.05). Regular monitoring should therefore be implemented so that the effect of genetic drift within subpopulations, enhanced by inbreeding, may be successfully minimized.

Alleles↗
PubMed1994

Genetic structures of non-penicillinase-producing Neisseria gonorrhoeae strains in relation to auxotype and serovar class.

The genetic relatedness of 354 non-penicillinase-producing Neisseria gonorrhoeae strains was studied by multilocus enzyme electrophoresis. The strains, isolated over 9 years in Spain, had different levels of susceptibility to penicillin and tetracycline. On the basis of results obtained by analysis at 12 enzyme loci, the strains were separated into 46 electrophoretic types (ETs). The average number of alleles per enzyme locus was 2.07, and the mean genetic diversity per locus was 0.26 for ETs and 0.27 for individual isolates. The distribution of strains among ETs was not linked to any particular auxotype or serovar class. The index of discrimination of auxotyping combined with serovar determination was similar to multilocus enzyme analysis. Classification of strains by auxotype and serovar did not seem to be related to genotype. Clustering analysis revealed that moderate penicillin-resistant and chromosomally mediated tetracycline-resistant strains were largely shared, while penicillin-resistant strains appeared only in some clusters.

Alleles↗
PubMed2000

[Influence of population's genetic structure on the load size of monogenic hereditary diseases in Russia].

The paper presents the results of genetic and epidemiological study of populations in 5 Russian regions: the Kirov, Kostroma, and Bryansk Provinces, Krasnodar Territory, and the Republic of Mari El. The total size of the study population was over 1.5 million. Random inbreeding (Fst) in all Russian rural populations was significant and varied from 0.34 x 10(-3) to 7.6 x 10(-3). The prevalence rates for autosomal dominant (AD) disorders ranged from 0.22 to 3.93 per 1000. The load of autosomal recessive (AR) disorders varied from 0.17 to 2.01. The prevalence rates for AD and AR disorders was twice lower in the urban populations than those in the rural ones. The prevalence of X-linked recessive disorders was 0.33 per 1000 males. An analysis was made to examine the correlation between inherited diseases and Fst. The Pierson correlation coefficient was 0.81 and 0.87 for AD and AR disorders, respectively. The regression suggested that genetic differentiation of the populations with genes for hereditary disorders is partially related to gene drift. This suggestion was proved by genetic geographical mapping analysis. The similarity in the patterns of genetic distance distribution for all 3 genetic systems was revealed by the correlation coefficients between the maps for neutral genetic markers and the genes of AD and AR disorders which were equal to 0.67 and 0.65. There was the highest correlation coefficient between the maps of genetic distances for the genes of AD and AR disorders (Rs = 0.88).

Consanguinity↗