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Tunisia is a country of great interest for human population genetics due to its strategic geographic position and rich human settlement history. These factors significantly contributed to the genetic makeup of present-day Tunisians harbouring components of diverse geographic origins. Here, we investigated the genetic structure of Tunisians by performing a mitochondrial DNA (mtDNA) comparison of 15 Tunisian population groups, in order to explore their complex genetic landscape. All Tunisian data were also analysed against 40 worldwide populations. Statistical results (Tajima's D and Fu's F S tests) suggested recent population expansion for the majority of studied populations, as well as showed (AMOVA test) that all populations were significantly different from each other, which is evidence of population structure even if it is not guided by geographic and ethnic effects. Gene flow analysis revealed the assignment of Tunisians to multiple ancestries, which agrees with their genetic heterogeneity. The resulting picture for the mtDNA pool confirms the evidence of a recent expansion of the Tunisian population and is in accordance with a mosaic structure, composed by North African, Middle Easterner, European and Sub-Saharan lineages, resulting from a complex settlement history. [ABSTRACT FROM AUTHOR]

Abstract: The peopling of São Miguel Island in the 15th century was made by Portuguese and settlers of foreign origin (Flemish, Jews, Moorish prisoners and black slaves), generating an admixture signature. Thus, to unravel São Miguel''s population genetic background and to characterize its population''s polymorphisms, we decided to establish a human DNA bank. Here, we describe the construction of the DNA bank and analyse the information of 997 samples obtained from healthy blood donors. The bank follows the international ethical guidelines, which include informed consent, confidentiality, anonymity of personal data, and abandonment in case of expressed will. DNA was isolated from blood samples, coded and immediately stored in a locked refrigerator. The identifiable DNA bank has self-reported data concerning sex, age, birth, current place of living, and parental birthplaces. The samples are representative of all the island''s municipalities (r =0.995, p <0.01). The majority (87%) of the participants is male, with mean age of 36.3 years (18–64 years). Birthplace analysis reveals that 902 (90%) have both parents born in São Miguel. Moreover, 477 (54%) have their parents born in the same locality, confirming a relatively high rate of consanguinity in rural area. To date, this DNA bank was used to assess the Y-chromosome phylogeny and diversity in Azorean population. Now, we are analysing autosomal STRs for the better understanding of the gene pool and genetic structure of the archipelago''s people. [Copyright &y& Elsevier]

The imbalance between reactive oxygen species (ROS) production and their elimination by antioxidants leads to oxidative stress. Depending on their concentration, ROS can trigger apoptosis or stimulate cell proliferation. We hypothesized that oxidative stress and mitochondrial dysfunction may participate not only in apoptosis detected in some myelodysplastic syndrome (MDS) patients, but also in increasing proliferation in other patients. We investigated the involvement of oxidative stress and mitochondrial dysfunction in MDS pathogenesis, as well as assessed their diagnostic and prognostic values. Intracellular peroxides, superoxide, superoxide/peroxides ratio, reduced glutathione (GSH), and mitochondrial membrane potential (Δψmit) levels were analyzed in bone marrow cells from 27 MDS patients and 12 controls, by flow cytometry. We observed that all bone marrow cell types from MDS patients had increased intracellular peroxide levels and decreased GSH content, compared with control cells. Moreover, oxidative stress levels were MDS subtype— and risk group—dependent. Low-risk patients had the highest ROS levels, which can be related with their high apoptosis; and intermediate-2-risk patients had high Δψmitthat may be associated with their proliferative potential. GSH levels were negatively correlated with transfusion dependency, and peroxide levels were positively correlated with serum ferritin level. GSH content proved to be an accurate parameter to discriminate patients from controls. Finally, patients with high ROS or low GSH levels, as well as high superoxide/peroxides ratio had lower overall survival. Our results suggest that oxidative stress and mitochondrial dysfunction are involved in MDS development, and that oxidative stress parameters may constitute novel diagnosis and/or prognosis biomarkers for MDS. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: The knowledge of population history, demography and genetic structure has proven to be fundamental to address research in human genetics. Here, we describe the genetic diversity of the Azorean population and its affinity with other populations by the analysis of 13 microsatellite loci (TPOX, D3S1358, FGA, CSF1PO, D5S818, D7S820, D8S1179, TH01, vWA, D13S317, D16S539, D18S51 and D21S11) in 222 unrelated blood donors. These short tandem repeat (STR) markers were typed by Polymerase Chain Reaction (PCR) with fluorescently labelled primers. Statistical analysis was performed using Arlequin v.2.0, and Nei''s genetic distance was calculated with DISPAN software and trees were constructed by Neighbor-Joining (NJ) using PHYLIP 3.63. To quantify the genetic contribution of Portuguese, African and European populations we calculated the admixture coefficient (mY) using Admix v. 2.0. The analysis of microsatellite loci shows that the Azorean population presents an average gene diversity of 0.776. For each marker, gene diversity ranges between 0.624 for TPOX and 0.882 for D18S51. Heterozygosity values calculated for each STR varies from 63.9% for TPOX to 89.2% for D18S51, although the majority of markers show values superior to 80%. In addition, the admixture coefficient reveals North Portuguese as the major contributor to the genetic background of the Azoreans. These results are corroborated by the dendrogram, in which Azores is closer to Belgians, Portuguese and Spanish, apart from Moroccans and Cabo Verdeans. Taken together, these data indicate that the gene pool of the Azorean population is very diverse and are consistent with our previous results on Y-chromosome. Moreover, no genetic differentiation between Azores and Portugal is observed. [Copyright &y& Elsevier]

Abstract: 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 a/b. 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. A Y-chromosomal haplotype was constructed for each individual using the seven loci. In total, 118 different haplotypes were observed in the 172-sample set (68.6% discriminatory capacity). Haplotype diversity value was high (0.9994), due to high variability of the Y-STRs. Moreover it is important to notice the great genetic diversity observed within the Azorean group. Microsatellite data indicate that the mean gene diversity (D) value for all the loci analysed in our sample set is 0.590 (values range from 0.4592 for DYS393 to 0.8212 for DYS385). Taken together, our analysis suggests that the current paternal pool of the Azorean population is, to a great extent (59.3%), of Portuguese descent with significant contributions from people with other genetic backgrounds. [Copyright &y& Elsevier]