PubMed
Abstracts - National Library of Medicine |
||
| Y-chromosome STR haplotypes in two population
samples: Azores Islands and Central Portugal. National Institute of Legal Medicine, Forensic Genetics of Coimbra, Largo da Se Nova, 3000 213 Coimbra, Portugal. The Y-chromosome haplotypes defined by nine STRs (DYS19, DYS385, DYS389I, DYS389II, DYS390, DYS391, DYS392 and DYS393) were studied in 207 unrelated individuals from Central Portugal and 63 from Azores Islands. The most common haplotype in Central Portugal was shared by 3.4% of the males, while 160 haplotypes were unique. In Azores Islands the most common haplotype was shared by 6.4% of the males, while 40 haplotypes were unique. The values of haplotype diversity were 0.993 for Central Portugal and 0.976 for Azores Islands. PMID: 12842354 [PubMed - indexed for MEDLINE] Forensic Sci Int. 2003 Jun 24;134(1):29-35. Genetic structure and origin of peopling in the Azores islands (Portugal): the view
from mtDNA. Unity of Anthropology, Department BABVE, Faculty of Sciences, Autonomous University of Barcelona, 08193 Bellaterra (Barcelona), Spain. Cristina.Santos@uab.es The Azores islands (Portugal), uninhabited when discovered by Portuguese navigators in the fifteenth century, are located in the Atlantic Ocean 1500 km from the European mainland. The archipelago is formed by nine islands of volcanic origin that define three geographical groups: Eastern (S. Miguel and Sta. Maria), Central (Terceira, Faial, Pico, Graciosa and S. Jorge) and Western (Flores and Corvo). To improve the genetic characterisation of the Azorean population, and to clarify some aspects related to the history of settlement, a study of mtDNA was conducted in the population of the archipelago. The HVRI region was sequenced and specific RFLPs were screened in 146 samples obtained from unrelated individuals with Azorean ancestry (50 from the Eastern group, 60 from the Central group, and 37 from the Western group). Samples were classified into haplogroups based on the information obtained from both sequencing and RFLP analysis. All the analyses performed support the idea that, in the whole group of islands, the majority of mtDNA lineages originated from the Iberian Peninsula, mainly from Portugal (mainland). However contributions from other European populations, especially from Northern Europe, cannot be disregarded. The values obtained for the various diversity parameters in the Azores archipelago indicate that the Azorean population, as a whole, does not exhibit the typical characteristics of an isolated population. The analysis of genetic data by groups of islands showed that the Western group exhibited particular features. The distribution of haplogroups in the Western group is very atypical, being significantly different from what is observed in the Eastern and Central groups. Furthermore, the diversity values are, in general, lower than those observed in other populations used for comparison. African haplogroups were found in all the groups of islands. Therefore the presence of Moorish and African slaves on the islands, as reported in historical sources, is supported by the mtDNA genetic data, especially in the Eastern group. The presence of Jews in the Central group is also supported by the mtDNA data. Neither historical nor genetic data (phylogeography of mtDNA) supports the idea of a differential settlement history for the Western group; however, it is represented in the phylogenies as an isolated branch. The effect of genetic drift, induced by the reduced population size since peopling occurred, has led to a very atypical distribution of haplogroups/haplotypes in this group of islands. We cannot ignore the influence of biodemographic and genetic processes, namely founder effect, genetic drift, migration, and even recent mutational events in the mtDNA lineages of the Azorean populations. Nevertheless, a great part of the variation in the Azorean mtDNA can be explained by the settlement history. PMID: 12940917 [PubMed - indexed for MEDLINE] Ann Hum Genet. 2003 Sep;67(Pt 5):433-56. Determination of human caucasian mitochondrial DNA haplogroups by means of a
hierarchical approach. Anthropology Unit, Department BABVE, Faculty of Sciences, Autonomous University of Barcelona, 08193 Bellaterra (Barcelona), Spain. In this paper we propose a hierarchical approach that allows the screening of mitochondrial DNA (mtDNA) haplogroups in populations that have essentially West Eurasian mtDNA backgrounds but that could have some non-West Eurasian contributions. To develop and validate this scheme, we used data on 18 coding region polymorphisms (17 analyzed by RFLP analysis and 1 by sequencing) and sequences of hypervariable segment I (HVSI) of the mtDNA control region from the Azores Islands (Portugal) population. The proposed scheme allows the characterization of almost all West Eurasian and African major clusters by means of RFLPs. Furthermore, the scheme includes information on situations in which sequencing is pertinent to defining a particular haplogroup. The validity of the scheme is ensured by (1) using relatively stable polymorphic positions, (2) screening more than one position to define a specific haplogroup, and (3) typing confirmatory positions. Dubious samples can be resolved by sequencing. The robustness of this approach was assessed by sequencing all samples for HVSI, taking advantage of the previously established relationships between RFLPs and control region sequence polymorphisms. The use of this hierarchical approach avoids the screening of unnecessary control region polymorphisms and therefore results in a more rapid and cost-efficient screening than one in which all polymorphic positions are analyzed. Even if this approach leads to a lower level of phylogeographic resolution than the sequencing of all samples, it allows us to define population movements on a continental level and can be applied, unlike sequencing all samples, with a low cost in any laboratory. PMID: 15481677 [PubMed - indexed for MEDLINE] Hum Biol. 2004 Jun;76(3):431-53. Allele frequencies and haplotypes of 8 Y-chromosomal STRs in the Santa Catarina
population of southern Brazil. National Institute Legal Medicine, 3000-213 Coimbra, Portugal. laurakaine@hotmail.com Allele frequencies and haplotypes of eight Y-chromosomal short tandem repeats (STRs), DYS19, DYS385, DYS389 I, DYS389 II, DYS390, DYS391, DYS392 and DYS393 were determined in a sample of 109 males from Santa Catarina. The origin of this southern Brazilian population is mainly from Portuguese people, namely from Azores archipelago. PMID: 15607594 [PubMed - indexed for MEDLINE] Forensic Sci Int. 2005 Feb 10;148(1):75-9. Analysis of Y-chromosome variability and its comparison with mtDNA variability reveals different demographic histories between islands in the Azores Archipelago (Portugal). Montiel R, Bettencourt C, Silva C, Santos C, Prata MJ, Lima M. Center of Research in Natural Resources (CIRN), University of the Azores, 9501-801 Ponta Delgada, Azores, Portugal. montiel@notes.uac.pt We determined the Y-chromosomal composition of the population of the Azores Islands (Portugal), by analyzing 20 binary polymorphisms located in the non-recombining portion of the Y-chromosome (NRY), in 185 unrelated individuals from the three groups of islands forming the Archipelago (Eastern, Central and Western). Similar to that described for other Portuguese samples, the most frequent haplogroups were R1(xR1b3f) (55.1%), E(xE3a) (13%) and J (8.6%). Principal components analysis revealed a Western European profile for the Azorean population. No significant differences between Azores and mainland Portugal were observed. However, the haplogroup distribution across the three groups of islands was not similar (P<0.003). The Western group presented differences in the frequencies of haplogroups R1, E(xE3a) and I1b2 (27.3%, 22.7% and 13.6%, respectively) when compared to the other two groups. An assessment of the NRY variability, and its comparison with mitochondrial DNA (mtDNA) variability, was further evidence of the differential composition of males during the settlement of the three groups of islands, contrary to what has been previously deduced for the female settlers using mtDNA data. PMID: 15720295 [PubMed - in process] Ann Hum Genet. 2005 Mar;69(Pt 2):135-44 The Y-chromosomal heritage of the Azores Islands population. Pacheco PR, Branco CC, Cabral R, Costa S, Araujo AL, Peixoto BR, Mendonca P, Mota-Vieira L. Molecular Genetics and Pathology Unit, Hospital of Divino Espirito Santo, 9500-370 Ponta Delgada, Sao Miguel Island, Azores, Portugal. The Azores, a Portuguese archipelago located in the north Atlantic Ocean, had no native population when the Portuguese first arrived in the 15th century. The islands were populated mainly by the Portuguese, but Jews, Moorish prisoners, African slaves, Flemish, French and Spaniards also contributed to the initial settlement. To understand the paternal origins and diversity of the extant Azorean population, we typed genomic DNA samples from 172 individuals using a combination of 10 Y-biallelic markers (YAP, SRY-1532, SRY-2627, 92R7, M9, sY81, Tat, SRY-8299, 12f2 and LLY22g) and the following Y-chromosomal STR systems: DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393 and DYS385. We identified nine different haplogroups, most of which are frequent in Europe. Haplogroup J* is the second most frequent in the Azores (13.4%), but it is modestly represented in mainland Portugal (6.8%). The other non-European haplogroups, N3 and E3a, which are prevalent in Asia and sub-Saharan Africa, respectively, have been found in the Azores (0.6% and 1.2%, respectively) but not in mainland Portugal. Microsatellite data indicate that the mean gene diversity (D) value for all the loci analysed in our sample set is 0.590, while haplotype diversity is 0.9994. Taken together, our analysis suggests that the current paternal pool of the Azorean population is, to a great extent, of Portuguese descent with significant contributions from people with other genetic backgrounds. PMID: 15720296 [PubMed - in process] Ann Hum Genet. 2005 Mar;69(Pt 2):145-56. Understanding Differences Between Phylogenetic and Pedigree-Derived mtDNA Mutation Rate: A Model Using Families from the Azores Islands (Portugal). Santos C, Montiel R, Sierra B, Bettencourt C, Fernandez E, Alvarez L, Lima M, Abade A, Aluja MP. Anthropology Unit, Department BABVE, Faculty of Sciences, Autonomous University of Barcelona, 08193 Bellaterra, Barcelona, Spain; daggerDepartment of Anthropology, University of Coimbra, 3000 Coimbra, Portugal; and double daggerCenter for Research in Natural Resources (CIRN), University of the Azores, 9500 Ponta Delgada, S. Miguel, Azores, Portugal. We analyzed the control region of the mitochondrial DNA (mtDNA) from maternally related individuals originating from the Azores Islands (Portugal) in order to estimate the mutation rate of mtDNA and to gain insights into the process by which a new mutation arises and segregates into heteroplasmy. Length and/or point heteroplasmies were found at least in one individual of 72% of the studied families. Eleven new point substitutions were found, all of them in heteroplasmy, from which five appear to be somatic mutations and six can be considered germinal, evidencing the high frequency of somatic mutations in mtDNA in healthy young individuals. Different values of the mutation rate according to different assumptions were estimated. When considering all the germinal mutations, the value of the mutation rate obtained is one of the highest reported so far in family studies. However, when corrected for gender (assuming that the mutations present in men have the same evolutionary weight of somatic mutations because they will inevitably be lost) and for the probability of intraindividual fixation, the value for the mutation rate obtained for HVRI and HVRII (0.2415 mutations/site/Myr) was in the upper end of the values provided by phylogenetic estimations. These results indicate that the discrepancy, that has been reported previously, between the human mtDNA mutation rates observed along evolutionary timescales and the estimations obtained using family pedigrees can be minimized when corrections for gender proportions in newborn individuals and for the probability of intraindividual fixation are introduced. The analyses performed support the hypothesis that (1) in a constant, tight bottleneck genetic drift alone can explain different patterns of heteroplasmy segregation and (2) in neutral conditions, the destiny of a new mutation is strictly related to the initial proportion of the new variant. Another important point arising from the data obtained is that, even in the absence of a paternal contribution of mtDNA, recombination may occur between mtDNA molecules present in an individual, which is only observable if it occurs between mtDNA types that differ at two or more positions. PMID: 15814829 [PubMed - as supplied by publisher] Mol Biol Evol. 2005 Jun;22(6):1490-1505. Epub 2005 Apr 6 Genetic structure of Flores island (Azores, Portugal) in the 19th century and
in the present day: evidence from surname analysis. |
||