Characteristics of Mongoloid populations based on the human immunoglobulin allotypes

Since the discovery of Gm ab3st haplotype which characterizes Mongoloid populations in 1966, the distribution of the genetic markers of immunoglobulins (Gm) among the Mongoloid populations scattered from Southeast Asia through East Asia to South America has been investigated and concluded as follows: 1) Mongoloid populations characterized by the four Gm haplotypes, ag, axg, ab3st and afb 1b3 are divided into two groups on the basis of analysis of genetic distances based on the Gm haplotype frequencies: one is a southern group characterized by a remarkably high frequency of Gm afb 1b3 and a low frequency of Gm ag and the other is a northern group characterized by a high frequency of Gm a and an extremely low frequency of Gm afb 1b3. 2) Populations in China, mainly Han including minority nationalities, show remarkable heterogeneities from north to south, in sharp contrast to Korean and Japanese populations showing homogeneities, respectively. The center of dispersion of the Gm afb 1b3 characterizing southern Mongoloids must exist in Guangxi and Yunnan area in the southwest China. 3) The Gm ab3st gene found in the highest incidence among the north Baikal Buriats flows in all directions. The gene, however, shows precipitous drop which occur from mainland China to Southeast Asia and from North to South-America, although the Gm ab3st gene is still found in high incidences among Eskimos, Yakuts, Tibetans, Olunchuns, Koreans, Japanese and Ainus. On the other hand, the gene is introduced into Huis, Uighurs, Indians, Iranians and far Hungarians.(ABSTRACT TRUNCATED AT 250 WORDS)     

A genetic survey in four Mongoloid populations of the Garo Hills, India

Four Mongoloid populations, viz., Garo , Hajong , Rabha and Koch, belonging to the Tibetoburman language family of Garo Hills, India, were examined for blood types ( A1A2BO , Rh, MN), secretor factor, ability to taste PTC and cerumen types. Gene A1 is more frequent than B in Hajong and Rabha . Garo shows a higher frequency of gene B, Koch also shows a little higher frequency of gene B than A. R1 is the commonest chromosome in all the groups followed by R2. Frequency of gene M is very high in all these populations. In respect of ABH secretion in saliva, there is preponderance of the secretor gene. Incidence of non- taster gene is somewhat lower in them. Dry cerumen gene is frequent in these Mongoloid groups. In general, the Garo Hills populations show closer affinity to the Mongoloids of Northeast India in respect of gene frequencies.     

MtDNA of Fulani nomads and their genetic relationships to neighboring sedentary populations

Despite the large size of the contemporary nomadic Fulani population (roughly 13 million people), the genetic diversity and degree of differentiation of Fulanis compared to other sub-Saharan populations remain unknown. We sampled four Fulani nomad populations (n = 186) in three countries of sub-Saharan Africa (Chad, Cameroon, and Burkina Faso) and analyzed sequences of the first hypervariable segment of the mitochondrial DNA. Most of the haplotypes belong to haplogroups of West African origin, such as L1b, L3b, L3d, L2b, L2c, and L2d (79.6% in total), which are all well represented in each of the four geographically separated samples. The haplogroups of Western Eurasian origin, such as J1b, U5, H, and V, were also detected but in rather low frequencies (8.1% in total). As in African hunter-gatherers (Pygmies and Khoisan) and some populations from central Tunisia (Kesra and Zriba), three of the Fulani nomad samples do not reveal significant negative values of Fu's selective neutrality test. The multidimensional scaling of FST genetic distances of related sub-Saharan populations and the analysis of molecular variance (AMOVA) show clear and close relationships between all pairs of the four Fulani nomad samples, irrespective of their geographic origin. The only group of nomadic Fulani that manifests some similarities with geographically related agricultural populations (from Guinea-Bissau and Nigeria) comes from Tcheboua in northern Cameroon.     

Polymorphism of complement component I in Mongoloid populations: a new genetic variant IF A2

The genetic polymorphism of the complement component I (IF) was investigated in 282 Chinese, 239 Koreans and 198 Japanese. The 3 common IF phenotypes (A, AB and B) and a new rare IF phenotype (BA2) were observed. The obtained allele frequencies are as follows: IF*A = 0.0993 and IF*B = 0.9007 in Chinese; IF*A = 0.0921 and IF*B = 0.9079 in Koreans; IF*A = 0.0985, IF*B = 0.8990 and IF*A2 = 0.0025 in Japanese. These 3 Mongoloid populations showed a much higher degree of IF polymorphism than Caucasian populations.     

Assessing temporal genetic variation in a cougar population: influence of harvest and neighboring populations

The geography of the Black Hills region of South Dakota and Wyoming may limit connectivity for many species. For species with large energetic demands and large home ranges or species at low densities this can create viability concerns. Carnivores in this region, such as cougars (Puma concolor), have the additive effect of natural and human-induced mortality; this may act to decrease long-term viability. In this study we set out to explore genetic diversity among cougar populations in the Black Hills and surrounding areas. Specifically, our objectives were to first compare genetic variation and effective number of breeders of cougars in the Black Hills during three harvest regimes: pre (2003–2006), moderate (2007–2010), and heavy (2011–2013), to determine if harvest impacted genetic variation. Second, we compared genetic structure of the Black Hills cougar population with cougar populations in neighboring eastern Wyoming and North Dakota. Using 20 microsatellite loci, we conducted genetic analysis on DNA samples from cougars in the Black Hills (n = 675), North Dakota (n = 113), and eastern Wyoming (n = 62) collected from 2001–2013. Here we report that the Black Hills cougar population maintained genetic variation over the three time periods. Our substructure analysis suggests that the maintenance of genetic variation was due to immigration from eastern Wyoming and possibly North Dakota.     

Introduction of new genetic markers on human chromosomes

The purpose of this study was to use DNA transfection and microcell chromosome transfer techniques to engineer a human chromosome containing multiple biochemical markers for which selectable growth conditions exist. The starting chromosome was a t(X;3)(3pter----3p12::Xq26----Xpter) chromosome from a reciprocal translocation in the normal human fibroblast cell line GM0439. This chromosome was transferred to a HPRT (hypoxanthine phosphoribosyltransferase)-deficient mouse A9 cell line by microcell fusion and selected under growth conditions (HAT medium) for the HPRT gene on the human t(X;3) chromosome. A resultant HAT-resistant cell line (A9(GM0439)-1) contained a single human t(X;3) chromosome. In order to introduce a second selectable genetic marker to the t(X;3) chromosome, A9(GM0439)-1 cells were transfected with pcDneo plasmid DNA. Colonies resistant to both G418 and HAT medium (G418r/HATr) were selected. To obtain A9 cells that contained a t(X;3) chromosome with an integrated neo gene, the microcell transfer step was repeated and doubly resistant cells were selected. G418r/HATr colonies arose at a frequently of 0.09 to 0.23 x 10(-6) per recipient cell. Of seven primary microcell hybrid clones, four yielded G418r/HATr clones at a detectable frequency (0.09 to 3.4 x 10(-6)) after a second round of microcell transfer. Doubly resistant cells were not observed after microcell chromosome transfers from three clones, presumably because the markers were on different chromosomes. The secondary G418r/HATr microcell hybrids contained at least one copy of the human t(X;3) chromosome and in situ hybridization with one of these clones confirmed the presence of a neo-tagged t(X;3) human chromosome. These results demonstrate that microcell chromosome transfer can be used to select chromosomes containing multiple markers.     

Analysis of genetic recombination in maize populations using molecular markers

Summary Variation in recombination rate is important to plant breeders since a major objective is to obtain favorable recombinants of linked genes. The ability to increase recombination (R) in circumstances in which favorable and unvavorable genes are linked (Corn Belt x exotic populations) and to decrease recombination when many favorable genes are linked (narrow-based, elite populations) would be of immense value. However, the concept of variation in recombination frequencies between linked genes has received limited attention despite its implications in breeding and genetic linkage studies. Molecular techniques have allowed better estimations of this variation. In this study, attempts were made to characterize: (1) the R values in the Pgm1-Adh1 and Adh1-Phi1 adjacent regions of chromosome 1 and the Idh2-Mdh2 region of chromosome 6 in F₂ families of three maize (Zea mays L.) populations; (2) the environmental effect on R values of F₂s from two populations. One population, NSO, was a Corn Belt synthetic, and the other two populations, CBMEX3 and CBCAR5, were composites from crosses between Corn Belt and exotic germ-plams.Wide ranges of estimated recombination ( ) values were observed among families in each population for all three chromsomal regions. The distribution of values for the Pgm1-Adh1 region showed that the F₂ families of each population fell into two broad categories: 0.30–0.50 and 0.02–0.20. No intermediates (0.21–0.29) were found. The distributions were almost normal for the Adh1-Phi1 and the Idh2-Mdh2 regions. It would appear that the major dispersion in the Pgm1-Adh1 region was controlled by the effects of a single gene, while the Adh1-Phi1 and Idh2-Mdh2 regions were only affected by polygenes. No correlation was found between recombination values of the two adjacent regions, indicating that the genes affecting recombination for the Pgm1-Adh1 region may be specific for that region.For the Pgm1-Adh1 region, no differences in values were found among the three populations. For the Adh1-Phi1 region, frequencies of CBMEX3 and NSO were not significantly different, but both had significantly greater values than CBCAR5. For the Idh2-Mdh2 region, CBMEX3 was significantly different from NSO. There were significant differences between some paired F₂ families within each population for each chromosome region.No significant differences in response to the two environments were detected in CBMEX3 and NSO for either region in chromosome 1.Published as Journal Paper No. 9498 of the Nebraska Agric Res Div, University of Nebraska, Lincoln, Neb. Research supported in part by USDA Competitive Grant 87-CRCR-2359     

Common genetic pools between human populations

Summary A further inquiry on modern human origins, based on common genetic pool surveys of rigorously selected population samples and highly informative immunological polymorphisms, provides new evidence of an Occidental-Oriental population split as the origin of human gene pool divergencies. The most likely ancestral genetic profile is discussed in the context of the debate raised by preliminary DNA restriction fragment length polymorphism studies, which contradict the conclusions drawn from classical blood group analyses.     

Molecular markers to study genetic drift and selection in wheat populations

Studying the heterogeneity in variation of gene frequency among populations or between generations may be a possible way to detect genomic regions experiencing selection. In order to evaluate this approach, RFLP markers were used to compare the allelic frequencies in wheat populations that had been submitted to natural selection. In 1984, samples of two composite cross populations were distributed in the French network for dynamic management of genetic resources. Since then, all the sub-populations have been cultivated in the same sites with no human selection. The strong differentiation between populations found for agro-morphological traits (earliness, resistance to pathogens, ...) provided evidence of their adaptation to local conditions. The two initial populations and six derived sub-populations cultivated for 10 years in four contrasted sites were studied with RFLP markers. Differentiation between sub-populations based on RFLP diversity was highly significant. Variations on allelic frequencies of the 30 loci scored were found to be much greater than expected under genetic drift only. This led us to conclude that selection greatly influenced the evolution of the populations. Some of the loci clearly presented a higher differentiation than the others. This might indicate that they were genetically linked to other loci polymorphic in the populations and involved in adaptation. However, the effect of one selected gene on a marker, even located very close to the gene, could not be predicted with certainty. Hence, though the populations were predominantly selfing, it seems that initial linkage disequilibriums between markers and selected genes were not strong enough to control closely the evolution of allelic frequencies at the markers.     

Distribution of hemoglobin E in several Mongoloid populations of northeast India

Nine-hundred seventy-eight subjects from eight Mongoloid tribes of northeastern India were investigated for the distribution of hemoglobin phenotypes by starch-gel electrophoresis. The sample included 157 Khasi and 24 Bodo from Cherrapunji (Meghalaya), 148, Rengma Naga and 81 Hmar of the Cachar district of Assam, 215 Adi from different subtribes, 216 Nishi, 79 Apatani, and a mixed group of 58 individuals from several other tribes of Arunachal Pradesh in northeast India. The frequency of HBB*E was found to be very low (0.01-0.02) in the Khasi, Naga, and Hmar tribes, whereas it varied from 0.06 to 0.18 among the tribes of Arunachal Pradesh. As expected, the Bodo group had a very high frequency of HBB*E (0.38), confirming earlier reports. It appears that the lack of HBB*E in the Austro-Asiatic (Khasi) and Naga-Kuki-Chin groups is probably due to the absence of malarial selection pressure as well as to isolation from their neighbors.     

Odontometric variation among American black, European, and Mongoloid populations

Quantified dental parameters (including root and pulp areas and shape variables) derived from periapical radiographs were used to make comparisons among a sample of American Black (8 males--124 teeth, 9 females--138 teeth), European derivative (31 males--304 teeth, 43 females--497 teeth) and Mongoloid populations (12 males--166 teeth, 19 females--252 teeth). The magnitude of sexual dimorphism within each ethnic stock was also examined. Teeth from American Black males were robust. Sexual dimorphism was unambiguous in all groups although a hierarchical order existed from the highly dichotomous American Black sample to the more homogeneous European sample. The female dental phenotype was down-scaled from their male counterparts, but not gracile in form. Easily obtained area and shape parameters derived from dental radiographs proved useful as discriminators among racial groups and the sexes. The relationships among these data lend further support to the hypothesis of an African origin of modern humans.     

A genetic affinity analysis of human populations

Genetic affinity of human populations based on allele frequency data was studied from two viewpoints. (1) The effect of the number of polymorphic loci on the reconstruction of a phylogenetic tree of human populations was empirically investigated. Genetic affinity trees were constructed based on data for 1–12 polymorphic loci, by using the neighbor-joining method. Geographical clustering of populations gradually appeared when the number of loci was increased. A new classification and terminology of higher order human population clusters is proposed based on these and other studies. (2) A new method of estimating the absolute divergence time of two populations is proposed, which is based on a diffusion equation that describes random genetic drift.     

Population genetic structure of Bactrocera dorsalis based on cox1 sequences from Bangladesh and neighboring countries

Oriental fruit fly, Bactrocera dorsalis (Hendel), is a destructive and highly polyphagous invasive fruit fly species of numerous fruit crops in global agriculture. Population genetic structure of this species from five different locations of Bangladesh was examined with other samples (collected from GenBank) from 15 sites of neighboring Asian countries. A fragment of 770 bp mitochondrial DNA cox1 was used to investigate the genetic diversity and the relationship between genetic patterns and geographical distribution of B. dorsalis. A total of 232 variable sites (33.23% of the 698 bp aligned consensus sequences) and 419 unique haplotypes were identified from 710 individuals. Indices of genetic diversity suggested that without exclusion from geographical areas, B. dorsalis retained a relatively high degree of genetic diversity. A demographic assessment [Tajimas’ D test, Fu’s Fs test and sum of square deviation (SSD values)] revealed that both current and historical variables performed a significant role in deciding the weak genetic structure with some exceptions. In Bangladesh, high levels of genetic diversity with a weak genetic structure indicated that the severity of this pest might increase in the future. Proper management techniques should be taken to overcome the future severity of this kind of destructive insect.     

Quantitative genetic variance associated with chromosomal markers in segregating populations

Summary Use of chromosomal markers can accelerate genetic progress for quantitative traits in pedigree selection programs by providing early information on Mendelian segregation effects for individual progeny. Potential effectiveness of selection using markers is determined by the amount of additive genetic variance traced from parents to progeny by the markers. Theoretical equations for the amount of additive genetic variance associated with a marker were derived at the individual level and for a segregating population in joint linkage equilibrium. Factors considered were the number of quantitative trait loci linked to the marker, their individual effects, and recombination rates with the marker. Subsequently, the expected amount of genetic variance associated with a marker in a segregating population was derived. In pedigree selection programs in segregating populations, a considerable fraction of the genetic variance on a chromosome is expected to be associated with a marker located on that chromosome. For an average chromosome in the bovine, this fraction is approximately 40% of the Mendelian segregation variance contributed by the chromosome. The effects of interference and position of the marker on this expectation are relative small. Length of the chromosome has a large effect on the expected variance. Effectiveness of MAS is, however, greatly reduced by lack of polymorphism at the marker and inaccuracy of estimation of chromosome substitution effects. The size of the expected amount of genetic variance associated with a chromosomal marker indicates that, even when the marker is not the active locus, large chromosome substitution effects are not uncommon in segregating populations.     

Genetic relationships between Indians and their neighboring populations

Using gene frequency data for 18 protein and blood group loci, we studied the genetic relationships of four Indian subcontinent populations (peoples from Punjab, Gujarati, Andhra Pradesh, and Bangladesh) with their neighboring populations (Iranians, Afghans, Sinhalese in Sri Lanka, Nepalese, Bhutanese, Malays, Bataks in northern Sumatra, and Chinese). The results obtained indicate that the four Indian subcontinent populations and the Sinhalese are genetically closer to Iranians and Afghans (Caucasoid) than to the other neighboring Mongoloid populations. Genetic distance analysis shows a clear-cut dichotomy between the Caucasoid and Mongoloid populations.