Riporto

[pensiero]

l'ho ricevuta via mail, spero come ho richiesto mi venga mandata la fonte....rischio bannaggio da pol a vita...ma tant'è io la posto


«Our data seem to confirm the hypothesis of Sandler et al. (1978) that underlines the African contribution to the Sicilian gene pool, because of the high frequencies of Hbs, cDe, and Fy (a-b-).
In a paper on mtDNA, Semino et al. (1989) found support for this hypothesis, dating back to the introduction of black slaves by Phoenicians and Romans and to the later influxes of Arab immigrants.»


«Genetic distances calculated with the Nei method (1972) are reported in Table 5. It was observed that the smallest distance lay between Germany and Hungary (0.0099) in comparison to the largest distance, which was between Palermo and Lombardy (0.2356).»


«A genetic boundary, in fact, clearly divides Sicily from north-central Italy and from northern European populations, besides the other populations from the western Mediterranean basin.»

[Iunthanaka]

Chissà che cosa ne penserebbe la Manuela Brown...

[Mitteleuropeo]

E avevate dubbi che i siculi scimmioni sono parenti di Bingo-Bongo??

[Bèrghem]

"Dal punto di vista genetico l'Italia settentrionale si rivela simile ai paesi dell'Europa centrale, mentre le regioni centrali e meridionali sono più vicine alla Grecia e agli altri paesi del Mediterraneo". (Storia e geografia dei geni umani, Cavalli-Sforza, Menozzi, Piazza, p. 519).




Saluti secessionisti.

[aussiebloke (POL)]

E' tratto da un lavoro di Calo, C. M., "Genetic analysis of a Sicilian population using 15 short tandem repeats", in Human Biology, April 2003.

CLICCARE QUI per l'articolo completo.

Molto interessante, anche le parti non quotate da pensy...
tipo quando trovano che la maggior somiglianza fra i vari samples e' quella
fra siciliani ed egiziani, mentre la massima differenza e' fra lombardi e siciliani.

Thread da leggere e tenere su il piu' possibile

[Nanths]

va bè mettiamolo anche qua...


Genetic analysis of a Sicilian population using 15 short tandem repeats
Human Biology, Apr 2003 by Calo, C M


Located 800 meters above sea level and about 80 km from Palermo (Sicily, Italy), Alia has a population of around 4000. In 1837 Alia, as well as all of Sicily, suffered a cholera epidemic that resulted in a dramatic reduction in its population. In 1995 an excavation uncovered the remains of about 300 individuals who had died from cholera. Interest in this population was highlighted by other studies based on analyses of mitochondrial DNA (mtDNA) (Vona et al. 2001) and classical genetic markers (Ghiani et al. 2002) that stressed the uniqueness of allele frequencies in the Alia population. The genetic peculiarity of this population may be due to its isolation and very low density. These two factors combined could have amplified the consequences of genetic drift. The aim of this study is to increase our knowledge about the genetic features of the population of Alia. Using some of the markers that we have analyzed in the present study, further information may be obtained from the comparison between the present population of Alia and the ongoing research into the subfossil remains resulting from the 1837 cholera epidemic.

Alia has undergone all of the historical incursions that have affected Sicily. Following the arrival of the first settlers on the island (Sycanians, Siculi, Elymians), Sicily, because of its position in the middle of the Mediterranean, has been invaded by Phoenicians, Greeks, Romans, Vandals, Goths, Arabs, Normans, and Spaniards. The contribution of all these different groups to the complex genetic constitution of the Sicilian population has yet to be accurately studied (Piazza et al. 1988; Rickards et al. 1992, 1998; Vona et al. 2000).

Materials and Methods

Blood samples were obtained from 50 unrelated, apparently healthy adults of both sexes, whose families were born and have lived in the same village of Alia for at least three generations. One of our researchers in Alia gathered the samples after obtaining informed consent from the donors. These samples were then taken to the Department of Experimental Biology of Cagliari University as well as the Raggruppamento Investigazioni Scientifiche of Carabinieri (RIS) in Parma for analysis. DNA was extracted from anonymous, whole blood samples using the traditional phenol-chloroform technique. Amplification by polymerase chain reaction (PCR) technique was performed using commercially available kits according to the manufacturers' recommendations (PE-ABD, Promega, USA). PCR was performed in a PE-ABD 2400 Thermal Cycler.

Electrophoresis was carried out on 5% polyacrylamide denaturing sequencing gels on a 377 automated system (PE-ABD). Data were analyzed by both Gene Scan v.3.1 and Genotyper v.2.0 software. The 15 short tandem repeats (STRs) studied were: TPOX, D2S1338, D3S1358, FIBRA, D5S818, CSF1PO, D7S820, D8S1179, TH01, VWA, D13S317, D16S539, D18S51, D19S433, and D21S11. Their characteristics are shown in Table 1.

Statistical Analysis. Allele frequencies were calculated from the genotypes using the gene counting method. Possible divergence from Hardy-Weinberg equilibrium was determined by the exact test method based on Markov chain analysis according to Guo and Thompson (1992) through the Genepop computer program (v.1.2) (Raymond and Russel 1995). Through the same program linkage disequilibrium for loci located on the same chromosome was tested. In addition, polymorphic information content (PIC) values were calculated by the use of the formula suggested by Hearne at al. (1992). The coefficient of gene diversity (G^sub ST^) (Nei 1973) and the genetic distance evaluations were obtained by employing the methods of Nei (Nei 1972) through the Phylip computer program, v.3.5c (Felsenstein 1989). Dendrogram construction of the genetic distances was performed with the neighbor-joining method (Saitou and Nei 1978). Furthermore, the existence of genetic boundaries within the island was tested through the Delauney network (Brassel and Reif 1979) and Monmonier's algorithm (1973). Genetic evidence for recent bottlenecks was evaluated for subpopulations with the Bottleneck computer program (Cornuet and Luikart 1996). This program tests whether H^sub obs^ significantly differs from H^sub exp^ under the mutation-drift equilibrium.

Results

Allele frequencies with markers under scrutiny in relation to the standard errors are shown in Table 2. The distribution of allele frequencies is unimodal for loci D8S1179, CSF1PO, and D5S818; multimodal for the rare alleles in loci D21S11 and FIBRA; and bimodal for all other alleles examined. Remarkably, within the Alia sample the presence of a rare allele (33.1) for locus D21S11 was discovered. In the samples there appear two heterozygote individuals (2%), which have not yet been observed in any other European population. The markers D2S1338 and D19S433, which have never before been used in research in population genetics and have only recently been put to use in forensic medicine (Garofano et al. 1999a; Garofano at al. 1999b), appear extremely polymorphic, showing 9 and 10 alleles each.

The exact test based on Markov chain analysis shows that all loci except TH01 are in Hardy-Weinberg equilibrium (Table 3). Of the 15 markers studied, two (TPOX and D2S1338) are located on chromosome 2 and two (CSF1PO and D5S818) are located on chromosome 15. The presence of linkage disequilibrium in each pair of loci located on the same chromosome was verified. The results, not shown, gave no significant values for either pair of loci.

The observed and expected heterozygosity as well as the PIC values for our samples are listed in Table 3. All loci had a high degree of heterozygosity, varying between 61.2% and 93.9% for TH01 and D18S51, respectively. Within the five markers D2S1338, D5S818, D7S820, THOl, and VWA, a decrease of heterozygosity had been observed and as a consequence an increase of homozygosity was observed. The polymorphic information content (PIC) was also calculated for each locus, except for loci TPOX and CSF1PO. All STRs showed PIC values ^gt;0.7, which is the limit value for use in linkage analysis (Hearne at al. 1992). Through the Bottleneck program (Cornuet and Luikart 1996), we discovered the indication of a recent bottleneck in the Alia population. Under the assumption of the Infinite Allele Model (IAM), all tests performed through the Bottleneck program (the sign, standardized differences, and Wilcoxon tests) showed a significant excessive heterozygosity in the Alia samples (p = 0.00001 and 0.00003, respectively). The data from Alia have been compared with those from seven other Sicilian regions, Agrigento, Caltanissetta, Catania, Messina, Palermo, Ragusa, and Siracusa (Barbara et al. 2000). Because of insufficient resources it was possible to compare only nine loci (D3S1358, D5S818, FIBRA, D7S820, D13S317, D18S51, D21S11), for a total of 93 alleles. G^sub ST^ values were then calculated in order to test for genetic diversity within Sicily (Table 3).

The genetic differentiation coefficient according to Nei (1973), G^sub ST^, showed the highest value for locus D21S11, while the lowest values were for VWA and D8S1179.

Genetic distances between Alia and other Sicilian populations were obtained by use of the Nei method (1972) (Table 4). They vary from a minimum of 0.0263 (Agrigento-Caltanissetta) to a maximum of 0.1993 (Catania-Palermo). Alia, in particular, showed the smallest distance from Ragusa and the largest from Palermo, despite the fact that it lies in the Palermo region. From the distances gathered from the matrix, a genetic tree was constructed using the neighbor-joining method (Saitou and Nei 1978) (Figure 1). The tree shows a clustered formation produced by Messina, Siracusa, and Catania, all located on the eastern coast of the island. The other four populations are located in two other distinct bunches, while Alia is not associated with any of the populations compared. From this previous comparison, other analyses were carried out using the data from the nine markers to obtain a total of 98 alleles, some of which have not been found in the Sicilian samples.

Data for comparison have been taken from the following European and Mediterranean countries: from Spain, the Basque Country (Perez-Lezaun et al. 2000), Catalonia (Gene et al. 1998; Gene et al. 2000), and Andalusia (Perez-Lezaun et al. 2000); from Italy, Lombardy and Tuscany (Barbara et al. 2000); from other countries, Portugal (Pinheiro et al. 2000), Switzerland (Gehrig 1998), Poland (Miscika-Sliwka et al. 1998), Germany (Hantshel et al. 1999; Seidl et al. 1998), Hungary (Furedi et al. 2000), Egypt (Klintschar et al. 1998; Klintschar et al. 1999), and Morocco (Perez-Lezaun et al. 2000). The genetic diversity involving these were calculated by use of the G^sub ST^ coefficient according to Nei (1973) (Table 3), with values ranging between 0.006 (D5S818) and 0.046 (D8S1179). Comparing all the observed values for the European and Mediterranean populations, it is possible in all cases to observe, with the exception of D8S1179, that the G^sub ST^ values for Sicily exceed those obtained for the compared populations. As a result, the overall G^sub ST^ calculated for the nine STRs for Sicily resulted in a value of 0.025 in contrast to 0.017 for the other compared populations.

Genetic distances calculated with the Nei method (1972) are reported in Table 5. It was observed that the smallest distance lay between Germany and Hungary (0.0099) in comparison to the largest distance, which was between Palermo and Lombardy (0.2356). With regards to the Alia sample, distances varied between 0.0310 (Alia-Hungary) and 0.1506 (Alia-Palermo), respectively.

The tree generated from the matrix, shown in Figure 2, compares the populations. The populations are located in two separate groups. One group consists of all the Sicilian populations and the Egyptian population, with the exception of Alia. It is worth observing that the Sicilian populations appear quite scattered in the tree with Palermo located on an isolated branch. The second group shows some associations in particular; the populations of Morocco and Andalusia are located together on a separate branch, as well as those of the Basque Country and Catalonia. The population of Alia is associated with those of Poland and Hungary. In comparison to the other populations, the populations of the Basque Country and of north and central Italy occupy a particular position.

Using the Delauney network, three genetic boundaries have been discovered (Figure 3). The first of these boundaries stretches from northern to southern Sicily and divides the island into two separate sections. The second boundary is shorter, separating Alia from the main center (Palermo). The third seems to divide Sicily from north-central Italy and from the other western Mediterranean populations.

Discussion

Using the allele frequencies of 15 STRs we were able to gather new data to aid in the analysis of the genetic structure for the population of Alia, a small village located along the interior of the mountainous chain of Madonie in Palermo, the main district of Sicily, Italy. The recent discovery of skeletal remains of victims of an 1837 cholera epidemic has brought a number of anthropologists, population geneticists, and demographers to Alia, not just for the skeletal remains but also because of the village's geographical and economic isolation (Bigazzi 2000; Vona et al. 2001; Ghiani et al. 2002). Results from analyses of classical markers (Ghiani at al. 2002) and mtDNA (Vona et al. 2001) showed that the genetic structure of Alia differed from that of other Sicilian and Mediterranean populations.

Results of the present study, based on 15 STRs, are similar to those of previous studies. Alia's population is isolated in comparison to other Sicilian populations, even from Palermo's population, in whose district Alia is located. The relatively high frequency of a rare allele, absent in the rest of Sicily, seems to reinforce the genetic isolation of Alia's population and thus confirms the hypothesis of a bottleneck as a consequence of the cholera epidemic. Here, the gene frequencies of the population would have been modified despite the fact that Alia has undergone the same prehistoric and historical events as western Sicily.

The genetic boundary between Alia and Palermo produced by the gene frequencies of the STRs studied could not be predicted, but can be explained by the bottleneck that occurred. A study of surnames in Alia existing before and after the 1837 epidemic corroborates the phenomenon that occurred (Bigazzi 2000). Only 127 out of 219 different surnames survived, confirming the occurrence of a dramatic and sudden decrease in the Alia population, which also affected its genetic structure. Isolation, the reduced number of surnames, and genetic drift are to be considered the major factors responsible for the genetic peculiarity of the Alia population. Confirmation of the bottleneck hypothesis has been supported through the results of the Bottleneck computer program analysis, following the method of Cornuet and Luikart (1996). It has been observed that the population of Alia showed a significantly higher heterozygosity than predicted by its allelic diversity. This heterogyzosity could be an expression of a recent reduction in the effective size of a population, for loci evolving under the IAM, a result of allelic diversity being reduced faster than heterozygosity. In a previous paper on the population of Alia based on mtDNA analysis (Vona et al. 2001), the authors hypothesized an expansion of the Alia population between 20,732 and 59,691 years ago. These two observations are not contradictory, because the bottleneck suggested by the results of the present study would have occurred around six generations ago, as a consequence of the 1837 cholera epidemic. The bottleneck therefore occurred very recently, but yet long after the expansion period. Moreover, it is well known that some genetic systems relatively and independently differentiate from others, and mtDNA certainly evolved and propagated differently than nuclear genes (Excoffier and Roessli 1990).

The overall G^sub ST^ value recorded was rather low. Analogous results observed for other populations for the same markers (Martinovic et al. 1999) or for other STRs (Jorde et al. 1995) have been interpreted as an effect of their high mutation rate (Jorde and Chakraborty 1995), which would determine a high heterogeneity within subpopulations (confirmed by high H^sub s^ values) and would tend to mask the variability among populations themselves.

The overall G^sub ST^ has been higher for Sicilian populations than for all the other populations compared. This value shows the existence of a genetic variability within Sicily that is considerably higher than that observed in the rest of Europe. Thus, the results obtained seem to indicate the existence of a strong heterogeneity within Sicily, as demonstrated by the genetic tree and by the presence of two genetic boundaries. Analogous boundaries have been discovered in a previous work on the population of Alia, which relied on the study of classical markers (Ghiani et al. 2002). Other authors, studying classical markers (Piazza et al. 1988; Cavalli-Sforza and Edwards 1969) and surnames (Guglielmino et al. 1991), have stressed the existence of genetic differentiation between the eastern and western areas of Sicily and, in general, a remarkable internal variation. In addition, the boundaries found within the Palermo district have been stressed as a sort of economic boundary in a study focusing on surnames (Zei et al. 1993). The variability that has been found could be a consequence of the various dominations that Sicily has undergone: Sycanians, Siculi, and Elymians to begin with (Piazza et al. 1988), followed by Greeks, Romans, Normans, and Arabs (Sandier et al. 1978; Beretta et al. 1986). Among these, Arab domination seems to have had a very strong genetic impact.

Analysis of the genetic tree confirmed the heterogeneity within Sicily by producing a separate branch on which the population of Alia appears. Further analysis shows within the same cluster a certain degree of affinity between Egypt and the populations of Sicily. The relationship between Sicilian and North African populations is controversial in population genetics (Piazza et al. 1988; Rickards et al. 1992; Rickards et al. 1998). Our data seem to confirm the hypothesis of Sandler et al. (1978) that underlines the African contribution to the Sicilian gene pool, because of the high frequencies of Hbs, cDe, and Fy (a-b-). In a paper on mtDNA, Semino et al. (1989) found support for this hypothesis, dating back to the introduction of black slaves by Phoenicians and Romans and to the later influxes of Arab immigrants.

The genetic tree allows some other observations. The affinity between Morocco and Andalusia reinforces what had been observed using classical markers and can be interpreted assuming the existence of an ancient common substratum and numerous contacts and exchanges between Spaniards and Arabs (Kandil et al. 1999). Other populations from the Iberian Peninsula appear in the genetic tree associated with another branch. Within this cluster, the Basque population differentiates itself from the others, thus confirming its genetic isolation. The peculiar and unexpected position of the Italian populations of Tuscany and Lombardy could be due to the presence of rare alleles, such as 28.2 and 29.2 for D21S11 in Lombardy and 13.2 and 14.2 for D18S51 in Tuscany, since high frequencies of these alleles occur in these populations. These populations appear strongly differentiated, even if compared with Sicily. A genetic boundary, in fact, clearly divides Sicily from north-central Italy and from northern European populations, besides the other populations from the western Mediterranean basin.

The 15 STRs examined in this study, which have successfully been employed in forensic analysis because of their high polymorphism and PIC values, seem useful in the analysis of the genetic structure of human populations. These markers support the peculiarity of the Alia population and the existence of a genetic differentiation between the western and eastern regions of Sicily. In addition, they highlight a certain degree of heterogeneity among the Sicilian, Italian, and European populations, by emphasizing the genetic boundaries.

Acknowledgments This research was supported by the Italian Ministere Universita Riccrca Scientifica e Tecnologica, Programmi Ricerca Scientifica di Rilevante Interesse Nazionale (ex-40% MURST, 1998-99). We are grateful to the entire population of Alia and its Mayor, Dr. G. D'Andrea, for their helpfulness and collaboration.

Copyright Wayne State University Press Apr 2003
Provided by ProQuest Information and Learning Company. All rights Reserved.

[pensiero]

veh...intelligentoni traduceteeeeeeeeeee

[Nanths]

In origine postato da pensiero
veh...intelligentoni traduceteeeeeeeeeee

impara l'inglese!!!!

[pensiero]

In origine postato da Nanths
impara l'inglese!!!!

gnanca dopo morta

[Nanths]

In origine postato da pensiero
gnanca dopo morta