Genetic population structure of Italy. I. Geographic patterns of gene frequencies

The diversity of spatial patterns of 61 allele frequencies for 20 genetic systems (15 loci) in Italy is presented. Blood antigens, enzymes, and proteins were analyzed. The total number of data points over all systems and localities was 1119. We used homogeneity tests, one-dimensional and directional spatial correlograms, and SYMAP interpolated surfaces. The data matrices were reduced by clustering techniques to reveal the principal patterns. Only a few allele frequency surfaces are strongly correlated across loci. All systems but one (ADA) exhibit significant heterogeneity in allele frequencies among the localities. Significant spatial patterns are shown by 27 of the 61 surfaces. Only one pattern (cde; system 4.19) is clinal; another (PGM1) exhibits a pure isolation by distance pattern; the others show long-range differentiation in addition to the short-distance decline of autocorrelation expected under isolation by distance. There is a marked decline in overall genetic similarity with distance for most variables. The 27 spatially significant alleles in Italy are also significantly patterned in Europe, but in all but 2 cases the country-wide and continent-wide patterns differ. The Italian patterns are due to forces specific to Italy. Differential selection for alleles associated with malaria is still evident. Whereas short-range differentiation can with malaria is still evident. Whereas short-range differentiation can be explained by isolation by distance, long-range differentiation appears to be due to demographic changes in certain populations that may be maintained by physical and linguistic isolation.     

Biochemical polymorphisms in South African freshwater fish. Isoenzyme patterns in fish of the families Cyprinidae and Salmonidae

Isoenzyme patterns were studied in local populations of the carp (Cyprinus carpio) and the bream (Sarotherodon mossambicus) of the Cyprinid family, and in the trout (Salmo giardneri) of the family Salmonidae. Homogenates of heart muscle extracts were used in the identification of PGI, NADP-IDH, PGM and 6-PGD. Polymorphisms found and gene frequencies obtained are discussed separately for each enzyme and species or population. In the bream, variation was found only at the PGI locus. In the carp only the PGM locus was polymorphic whereas both PGM and IDH showed variation in the trout. The variation at the PGM locus in the trout cannot support the three locus model suggested elsewhere and clearly indicates a single locus for the monomeric enzyme. The large variety of NADP-IDH types in trout not only illucidates the complexity of this locus but confirms a disomic mode of inheritance. Genetic differences in the trout populations could be related to possible advantages for management purposes.     

Biochemical polymorphisms in South African freshwater fish. Isoenzyme patterns in fish of the families Cyprinidae and Salmonidae

Isoenzyme patterns were studied in local populations of the carp ( Cyprinus carpio ) and the bream ( Sarotherodon mossambicus ) of the Cyprinid family. and in the trout ( Sabno giardneri ) of the family Salmonidae. Homogenates of heart muscle extracts were used in the identification of PGI. NADP-IDH. PGM and 6-PGD.
Polymorphisms found and gene frequencies obtained are discussed separately for each enzyme and species or population.
In the bream, variation was found only at the PGI locus. In the carp only the PGM locus was polymorphic whereas both PGM and IDH showed variation in the trout. The variation at the PGM locus in the trout cannot support the three locus model suggested elsewhere and clearly indicates a single locus for the mo-nomeric enzyme.
The large variety of NADP-IDH types in trout not only illucidates the complexity of this locus but confirms a disomic mode of inheritance. Genetic differences in the trout populations could be related to possible advantages for management purposes.     

Phophoglucomutase first locus polymorphism as revealed by isoelectric focusing in Southern Africa

Eleven Southern African populations (representing European, Asian and Negroid populations) have been typed for the first locus phosphoglucomutase (PGM1) using isoelectric focusing (pH range 5.0-8.0) in acrylamide gels. The gene frequencies of the four common alleles at this locus in these populations were compared to those found previously in European and Negroid populations. Marked differences in gene frequencies were observed: Negroes have a lower PGM1(2-) compared with Caucasoids due to a lower PGM1(2-) frequency, Indians a relatively high PGM1(2) due to a higher frequency of the PGM1(2+) allele. The Afrikaans and Ashkenazim do not differ appreciably from their European counterparts. The appearances of the rarer PGM1(6) and PGM1(7) alleles on isoelectric focusing are described and some kinetic properties examined. The PGM2(2-1), or 'Atkinson' phenotype, can also be detected with this technique.     

Phosphoglucomutase-1 subtypes: polymorphic occurrence of PGM1*7+ and geographical variation in Japan

The distribution of gene frequencies in the phosphoglucomutase-1 (PGM1) system was investigated in two Japanese populations from Yamaguchi (Western Japan) and Okinawa (Southern Japan) using an improved isoelectric focusing method permitting the successful detection of the most anodal variant PGM1 3+. PGM1*7+ occurred with a polymorphic frequency of 0.012-0.021. A difference in the gene frequency was observed between the two populations. In comparison with neighboring populations, the Yamaguchi population was similar to Mongolians and Koreans in North China, and Okinawa to Zhuang in South China.     

Polymorphism of immunological and biochemical marker genes in rural populations of the Tuva Republic

This article continues the series of publications on the population genetic structure of the Tuva Republic. The polymorphism of immunological (ABO, MN, and the Dd locus of Rhesus) and biochemical (TF, GC, HP, PGD, PGM1, ACP1, and ESD) marker systems was studied in three rural populations of the Tuva Republic: the Shinaanskii, Todzhinskii, and Bai-Taiginskii populations (the Kungurtug, Toora-Khem, and Teeli villages, respectively). Genetic subdivision of the populations and genetic distances between the Tuvinian populations and the populations of neighboring regions were estimated. Tuvinians were demonstrated to be genetically heterogeneous. Data on their population-genetic structure with respect to several classical marker systems agree with the results obtained for quasigenetic (family names) and molecular (mtDNA) markers. Prolonged isolation of individual populations in the republic promoted formation of specific patterns of gene frequencies in some of them. These patterns account for differences between Tuvinians and other populations belonging to the Altaic language family. Tuvinians in general are genetically closer to Mongolian populations inhabiting the regions bordering the Tuva Republic than to southern Altaians.     

Subtyping of phosphoglucomutase locus 1 (PGM1) polymorphism in some populations of Rwanda: description of variant phenotypes, "haplotype" frequencies,and linkage disequilibrium data.

Some populations of Rwanda (South Twa Pygmies, Hutu, and Tutsi) have been analyzed by acid starch gel electrophoresis for the subtyping of PGM1 polymorphism. The new polymorphic third PGM11 allele, the PGM1(1Twa), which we recently detected in Twa Pygmies from North Rwanda, has not been found in this survey, whereas the rare PGM1(6) allele attains subpolymorphic frequencies in all groups. Comparison between the various populations of Rwanda shows that they differ significantly from each other with the exception of South Twa Pygmies and Tutsi. A relatively low frequency (9.6%) of the PGM1(2S) allele appears to be typical of North Twa Pygmies; a low frequency of PGM1(2F) (1.2%-3.6%) has been found in all these groups but not in the Hutu (6.4%); and a particularly high incidence of the PGM1(1F) allele (the highest so far reported) has been observed in the South Twa Pygmies (20%) and in the Tutsi (18%). The PGM1(1Twa) and PGM1(6) enzymes, which in acid starch gel are not distinguishable, can be clearly differentiated by isoelectric focusing. In addition, the same technique has shown that the rare PGM1(7) allele observed in one Hutu is different from that found at polymorphic frequency in the Japanese and from a rare PGM1(7) allele found in Germany. On the very likely hypothesis that the PGM1(1S), PGM1(1F), PGM1(2S), and PGM1(2F) result from variations at two different polymorphic sites, 1/2 and F/S, within the PGM1 structural gene, all the available population data have been analyzed to investigate whether preferential combinations (haplotypes) were identifiable. Whereas Caucasians show a prevalence of 2F and 1S combination with an 8.02% mean value of linkage disequilibrium expressed as % Dmax, from the very few and scattered African data, it is impossible to draw any inference at present.     

Genetic studies of phosphoglucomutase-1 (PGM1) subtypes: population aspects]

Distribution of the subtypes and gene frequencies of phosphoglucomutase-1 among some populations of Buryats, Kirghizes of the Pamir and Russians of Moscow district was analysed. The frequencies of PGM1 genes vary in Buryats being PGM1+(1) 0.647-0.743, PGM1-(1)-0.100-0.132, PGM2+(1)-0.122-0.199 and PGM2-(1)-0.007-0.037. Following frequencies of PGM1 genes were established for Kirghizes: PGM1+(1) = 0.614, PGM1-(1) = 0.114, PGM2+(1) = 0.217 and PGM2-(1) = 0.054; in Russian populations the frequencies were: PGM1+(1) = 0.578, PGM1-(1) = 0.110, PGM2+(1) = 0.253 and PGM2-(1) = 0.059. Peculiarities of PGM1 polymorphism in the USSR and all over the world were analysed. Parallel biodemographic investigations in Buryat population demonstrated differences in intensities of selection, related to concrete PGM genotypes.     

Gene pool of Dagestan ethnic groups: polymorphism of classical gene markers in the Darghin ethnic group

The work is part of a study of the gene pool for Daghestan ethnic groups. In total, 38 alleles and eight genotypes were studied at 14 loci (AB0, Rhesus, P, Lewis, Kell, HP, GC, C'3, TF, 6-PGD, GLO1, ESD, ACP, and PGM1) of immunogenetic and biochemical polymorphic gene systems. A high frequency of allele d of the Rhesus system was observed in all populations examined (0.399-0.474). Among the rare haplotypes of the Rhesus system, we observed CDE in the Degva population, Cde in the Sergokala and Degva populations, and cdE in the Sergokala and Vanashimakhi populations. The typical Caucasian ACP1c allele of the ACP1 locus, which is rather uncommon, was observed at a relatively high frequency in three (Segokala, Vanashimakhi, and Gubden) of the four local populations under study. In the Lewis system, a high frequency of the Le(a+b+) phenotype, which is characteristic of early childhood, was detected in the adult populations of Sergokala and Degva. The rare PGM1v allele of the phosphoglucomutase 1 system (PGM 1) was additionally observed in the Sergokala population. Statistical analysis identified 19 cases where the observed phenotype frequencies significantly differed from the frequencies expected from the Hardy--Weinberg equilibrium.     

Allozyme frequencies in western European populations of Asellus aquaticus (L.) Isopoda and their association with water pollution

A study was made of allozyme variation in western European populations of Asellus aquaticus. Two enzymes were examined glucose phosphate isomerase (CPI) and phosphoglucomutase (PGM).
The populations show significant latitudinal clincs for GPI and PGM with the GPI-2 and PGM-2 alleles increasing in more southerly latitudes. While GPI-2 frequencies in British populations are consistent with the overall clinc, considered separately they show a reverse cline. This appears to be the result of a strong association of GPI-2 frequencies with water pollution combined with the geographic distribution of the polluted sites.
The association of high GPI-2 frequencies with high levels of water pollution is present in two independent sets of populations in Britain, and is more specifically associated with low levels of environmental oxygen. This latter association also occurs independently in temporal studies made at three locations. However, an additional temporal association of high GPI-2 frequencies with high temperatures also exists, consistent with the observed latitudinal cline. A study of adult mortality by oxygen deprivation at different temperatures suggests that both temperature and oxygen concentrations may act selectively with the GPI 2-2 genotype to be favoured under certain conditions. In contrast to GPI, PGM allozymes do not appear to be associated with pollution related variables.
The findings of the study point to selection acting on the two loci examined, though most convincingly for GPI. However, it remains to be demonstrated that selection is acting directly on the loci, and if so, how it operates to produce the patterns of allozyme variation observed in nature.     

The Russian gene pool. Genogeography of erythrocyte genetic markers (ACP1, PGM1, ESD, GLO1, 6-PGD)

The study continues the series of works on the Russian gene pool. Gene geographic analysis of five erythrocytic gene markers best studied in the Russian population (ACP1, PGM1, ESD, GLO1, and 6-PGD) has been performed. Gene-geographic electronic maps have been constructed for 13 alleles of these loci and their correlations with geographic latitude and longitude. For all maps, statistical characteristics are presented, including the variation range and mean gene frequencies, partial and multiple correlations with latitude and longitude, and parameters of heterozygosity and interpopulation diversity. The maps of eight alleles (ACP1*A, ACP1*C, PGM1*2+, PGM1*2-, PGM1*1-, ESD*1, GLO1*1, and PGD*C) are shown and analyzed in detail. The genetic relief and structural elements of the maps are compared with the ecumenical trends, main variation patterns of these genes in northern Eurasia, and genetic characteristics of the indigenous populations of the Urals and Europe.     

AK, PGM1 and 6PGD polymorphisms in Central Sardinia

Adenylate kinase (AK), phosphoglucomutase (PGM1) and 6-phosphogluconate dehydrogenase (6PGD) polymorphisms were investigated in a sample of individuals from Central Sardinia. The gene frequencies were: AK1 = 0.973, PGM1(1) = 0.842 and PGDA = 0.969. The frequencies were compared with those of other Italian populations.     

Genetic structure of the population of Sicily.

Genetic heterogeneity within Sicily was investigated on the basis of ACP1, ADA, ESD, GLO1, PGD, PGM1, PGM2, SODA, ABO, and MN gene frequencies, and compared to those of other regions of Italy for which these same loci have been examined. Correspondence analysis revealed no differences within the island, at least at the provincial level, but showed genetic differentiation among Italian regions, distinctly clustering northern, central, and southern populations, respectively. These data indicate a close relationship between Sicily and southern Italy. In addition, the contribution of Middle Eastern populations to the gene pool of Sicily was evident.     

Serum proteins and erythrocyte enzymes. Evaluation of frequencies in 2 populations in the Gabon

The results of the electrophoretic phenotyping of two serum groups (C'3 and Transferrine) and seven red cell enzymes (PAc, PGM, AK, ADA, 6PGD, sGPT and Est D) in two groups of negroes from Gabon are presented. The frequencies are in the normal range observed for African populations except for acid phosphatase in Southern Africa; Khoisan people have frequencies of the "Negroe allele R" higher than in any other population of the world. In Obamba and Bateke populations frequencies of Pr is 0.013.     

Allozyme polymorphism of Swiss stone pine Pinus cembra L. in mountainous populations of the Alps and the Eastern Carpathians

Swiss stone pine Pinus cembra L. is a species with fragmented range, occurring in the Alpine-East Carpathian mountain system. Seeds of P. cembra are dispersed by nutcrackers, which offers potential possibilities for gene exchange among populations. Using isozyme analysis, we have examined five samples from two parts of the Swiss stone pine range: the Alps (Switzerland and Austria) and the Carpathians (two samples from the northern macroslope of the Gorgany Ridge, Eastern Carpathians, Ivano-Frankovsk oblast and one sample from Trans-Carpathian oblast of Ukraine). The allele frequencies of 30 isozyme loci, coding for enzymes ADH, FDH, FEST, GDH, GOT, IDH, LAP, MNR, MDH, PEPCA, 6PGD, PGI, PGM, SDH, SKDH, SOD, were analyzed using cluster analysis and methods of principal components. Two clusters, corresponding to the isolated Alpine and Carpathian parts of the range, were found. The main contribution to these differences were made by loci Adh-1, Adh-2, Fest-2, Lap-3, Mdh-4, and Sod-4. The interpopulation differentiation proved to be somewhat higher than that typical for pines (F(ST) = 7.4%), but within the limits characteristic for taxonomically close species. Thus, isolation of the populations did not lead to their marked differentiation, which may be explained by gene flow and balancing selection, which equalizes gene frequencies across the fragmented species area. Interlocus F(ST) heterogeneity (from 0.003 to 0.173) suggests adaptive significance of some of the allozyme polymorphisms or linkage of some loci with adaptive genes. The Carpathian populations were shown to have higher gene diversity than the Alpine ones (expected heterozygosities 0.095-0.114 and 0.060-0.080, respectively). A deficit of heterozygotes (as compared to the Hardy-Weinberg proportions), observed in the embryo sample, was probably explained by inbreeding. The reduction in the area of Carpathian pine forests in Holocene, caused by the global climatic changes and the anthropogenic impact, is hazardous for the gene pool of the species. The maintenance of genetic uniqueness of both Carpathian populations of P. cembra in general, and individual stands in particular, requires special measures for protection of Swiss stone pine in the Eastern Carpathians.     

Geographical patterns of allozymic variation in three species of intertidal sculpins

Synopsis We examined spatial patterns of allozyme variation in three species of intertidal cottids to evaluate how much gene flow occurs between geographically separate populations (most likely via passive dispersal of planktonic larvae by currents). Our results from the analysis of geographical patterns of allele frequencies and, to some extent, from comparison of allele frequencies between newly recruited young and older resident fish are consistent with the notion that sufficient gene flow occurs in these fishes to prevent significant genetic isolation of populations. From these results, we visualize evolutionary changes in populations of these species as occurring most likely over a broad geographic scale, affecting spatially separated but genetically linked populations concurrently, rather than operating independently in individual, genetically isolated populations.     

PGM1 and TF subtypes and C3 polymorphisms in Continental Italy and Sardinia. Data on the world distribution of these genetic markers

PGM1, TF and C3 polymorphisms have been examined in two Italian samples, collected in continental Italy and in Sardinia (Cagliari). The PGM1 and TF subtypes were determined by isoelectric focusing while the C3 was studied by conventional methods. A significant difference in the gene frequencies of PGM1 and TF systems between our two samples has been observed. In addition, data on the world distribution of PGM1, TF and C3 polymorphisms have been presented.     

Genetic structure of Mongolic-speaking Kalmyks.

Genetic polymorphisms of blood groups ABO and RH D, serum proteins HP, TF, and GC, and red cell enzymes ACP1, PGM1, ESD, GLO1, and SOD-A have been reported for three tribes (Torguts, Derbets, and Buzavs) of the Volga's Kalmyk-Oyrats. The Kalmyks exhibit genetic markers that are characteristic of Central Asian populations, namely, high allelic frequencies for ABO*B, TF*C2, GC*IF, ESD*2, and GLO1*2, and the rare incidence of individuals with the RH-negative phenotype. Genetic distance measures reveal that close genetic affinities exist between the Derbets and Buzavs, but both populations differ significantly from the Torguts. Collectively as an ethnic group, the Kalmyks genetically resemble the contemporary Buryats of the Baikal region of southeastern Siberia and the Mongols of Mongolia. The transplantation of the Kalmyk-Oyrats from their homeland near Lake Baikal to their current residence (4500 km) near the Caspian Sea and their subsequent isolation for more than 300 years have not appreciably altered the gene frequencies from the parental populations for frequencies of standard genetic markers.     

Isoelectric subtyping of the PGM1 in the Icelandic population

Phenotypes for the red blood cell enzyme phosphoglucomutase (PGM1) were determined by isoelectric focusing for a population of 2,501 Icelandic individuals. All ten phenotypes were observed, and the frequencies of four alleles at the PGM1 locus were as follows: PGM1 1+=0.6875; PGM1 1−=0.1124; PGM1 2+=0.1419, and PGM1 2−=0.0582. These results have been compared with those found in other northern European populations.