[Show abstract][Hide abstract] ABSTRACT: Complex toxicant mixtures present in estuarine sediments often render contaminant screening unfeasible and compromise determining causation. HepG2 cells were subjected to bioassays with sediment extracts obtained with a series of progressively polar solvents plus a crude extract. The sediments were collected from an impacted area of an estuary otherwise regarded as pristine, whose stressors result mostly from aquaculture effluents and hydrodynamic shifts that enhance particle deposition. Compared to a reference scenario, the most polar extracts yielded highest cytotoxicity while higher genotoxicity (including oxidative damage) was elicited by non-polar solvents. While the former caused effects similar to those expected from biocides, the latter triggered effects compatible with known pro-mutagens like PAHs, even though the overall levels of toxicants were considered of low risk. The results indicate that the approach may constitute an effective line-of-evidence to infer on the predominant set of hazardous contaminants present in complex environmental mixtures.
[Show abstract][Hide abstract] ABSTRACT: Estuarine sediments may be reservoirs of hydrophilic and hydrophobic pollutants, many of which are acknowledged genotoxicants, pro-mutagens and even potential carcinogens for humans. Still, studies aiming at narrowing the gap between ecological and human health risk of sediment-bound contaminant mixtures are scarce. Taking an impacted estuary as a case study (the Sado, SW Portugal), HepG2 (human hepatoma) cells were exposed in vitro for 48h to extracts of sediments collected from two areas (urban/industrial and Triverine/agricultural), both contaminated by distinct mixtures of organic and inorganic toxicants, among which are found priority mutagens such as benzo[a]pyrene. Comparatively to a control test, extracts of sediments from both impacted areas produced deleterious effects in a dose-response manner. However, sediment extracts from the industrial area caused lower replication index plus higher cytotoxicity and genotoxicity (concerning total DNA strand breakage and clastogenesis), with emphasis on micronucleus induction. On the other hand, extracts from the rural area induced the highest oxidative damage to DNA, as revealed by the FPG (formamidopyrimidine-DNA glycosylase) enzyme in the Comet assay. Although the estuary, on its whole, has been classified as moderately contaminated, the results suggest that the sediments from the industrial area are significantly genotoxic and, furthermore, elicit permanent chromosome damage, thus potentially being more mutagenic than those from the rural area. The results are consistent with contamination by pro-mutagens like polycyclic aromatic hydrocarbons (PAHs), potentiated by metals. The sediments from the agriculture-influenced area likely owe their genotoxic effects to metals and other toxicants, probably pesticides and fertilizers, and able to induce reactive oxygen species without the formation of DNA strand breakage. The findings suggest that the mixtures of contaminants present in the assayed sediments are genotoxic to HepG2 cells, ultimately providing a useful approach to hazard identification and an effective line-of-evidence in the environmental monitoring of anthropogenically-impacted coastal ecosystems.
Science of The Total Environment 01/2014; 478:25–35. · 3.26 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Chronic haemolysis stands out as one of the hallmarks of sickle-cell anaemia, a clinically heterogeneous autosomal recessive monogenic anaemia. However, the genetic architecture of this sub-phenotype is still poorly understood. Here we report the results of an association study between haemolysis biomarkers (serum LDH, total bilirubin and reticulocyte count) and the inheritance of 41 genetic variants of ten candidate genes in a series of 99 paediatric SS patients (median current age of 9.9 years) followed-up in two general hospitals in Greater Lisboa area (median follow-up/patient of 5.0 years). Although in a large number of tests a seemingly significant (i.e., p<0.05) association was observed, the following ones were confirmed upon correction for multiple comparisons: (i) an elevated serum LDH was associated to haplotype 7 within VCAM1 gene; (ii) a lower total bilirubin was associated to the 3.7kb deletion at HBA gene, rs2070744_T allele at NOS3 gene, and haplotype 9 within VCAM1 promoter; and (iii) a diminished reticulocyte count was associated to the 3.7kb deletion at HBA, whereas an elevated count was associated to rs1984112_G allele at CD36 gene. On the whole, our findings suggest a complex genetic architecture for the sickle cell anaemia haemolysis process involving multiple pathways, namely control of vascular cell adhesion, NO synthesis and erythrocyte volume and haemoglobinisation. This article is protected by copyright. All rights reserved.
European Journal Of Haematology 10/2013; · 2.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have estimated the incidence and molecular basis of α-thal-assemia in a Portuguese population, mostly from the Greater Lisbon area. In a group of 100 consecutive cord blood samples, the gene frequency of the rightward deletion (-α3.7) was 0.035, and the leftward deletion (-α4.2) was 0.015. In this group, we have also found four heterozygotes for the triple α-globin gene rearrangement (αααanti3.7 gene frequency 0.020). We have characterized the subtypes of -α3.7 and αααanti3.7 rearrangements. On the whole, these results give an incidence of 10% for deletional a-thalassemia carriers in the studied Portuguese population In a group of 342 subjects presenting β-thalassemia, or Hb S trait, β-thalassemia major, sickle cell disease or low red blood cell indices, the -α3.7, -α4.2, –SEA –MED (αα)MM and αααanti3.7 haplotypes were found in different combinations. Only one nondeletional α-thalassemia determinant (a 5 nucleotide deletion in the α2-globin gene in the second intervening sequence donor site) was detected, which might suggest a low incidence of these defects in the Portuguese population
[Show abstract][Hide abstract] ABSTRACT: Most studies of European genetic diversity have focused on large-scale variation and interpretations based on events in prehistory, but migrations and invasions in historical times could also have had profound effects on the genetic landscape. The Iberian Peninsula provides a suitable region for examination of the demographic impact of such recent events, because its complex recent history has involved the long-term residence of two very different populations with distinct geographical origins and their own particular cultural and religious characteristics-North African Muslims and Sephardic Jews. To address this issue, we analyzed Y chromosome haplotypes, which provide the necessary phylogeographic resolution, in 1140 males from the Iberian Peninsula and Balearic Islands. Admixture analysis based on binary and Y-STR haplotypes indicates a high mean proportion of ancestry from North African (10.6%) and Sephardic Jewish (19.8%) sources. Despite alternative possible sources for lineages ascribed a Sephardic Jewish origin, these proportions attest to a high level of religious conversion (whether voluntary or enforced), driven by historical episodes of social and religious intolerance, that ultimately led to the integration of descendants. In agreement with the historical record, analysis of haplotype sharing and diversity within specific haplogroups suggests that the Sephardic Jewish component is the more ancient. The geographical distribution of North African ancestry in the peninsula does not reflect the initial colonization and subsequent withdrawal and is likely to result from later enforced population movement-more marked in some regions than in others-plus the effects of genetic drift.
The American Journal of Human Genetics 01/2009; 83(6):725-36. · 11.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Elevated erythrocyte destruction in sickle cell disease (SCD) results in chronic hyperbilirubinaemia and, in a subset of patients, cholelithiasis occurs. We investigated whether the (TA)n promoter polymorphism in the UDP-glucuronosyltransferase 1A1 gene (UGT1A1) may modify bilirubin metabolism, influencing bilirubinaemia, predisposition to cholelithiasis and subsequent cholecystectomy, in a group of 153 young SCD patients (mean age 12.0 +/- 9.0 years) predominantly of Bantu beta S haplotype. The concomitant effect of alpha thalassaemia was also analysed. Among the several UGT1A1 genotypes found, the most frequent were the (TA)6/(TA)6 (n = 37), (TA)6/(TA)7 (n = 60) and (TA)7/(TA)7 (n = 29). These groups of patients did not significantly differ in age, gender ratio and haemoglobin, foetal haemoglobin and reticulocyte levels. On the other hand, total bilirubin levels were significantly different between groups, with an increased (TA) repeat number being associated with higher bilirubinaemia. Furthermore, both cholelithiasis and cholecystectomy were more frequent in groups with higher (TA) repeat number, although the former association was not statistically significant. None of the mentioned parameters is statistically different within UGT1A1 groups with the presence of alpha thalassaemia. Thus, the UGT1A1 promoter polymorphism may represent an important nonglobin genetic modifier of Bantu SCD patients' clinical manifestations, even at a young age.
Journal of Human Genetics 02/2008; 53(6):524-8. · 2.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Nonsense-mediated mRNA decay (NMD) is a surveillance mechanism that degrades mRNAs containing premature translation termination codons. In mammalian cells, a termination codon is ordinarily recognized as "premature" if it is located greater than 50-54 nucleotides 5' to the final exon-exon junction. We have described a set of naturally occurring human beta-globin gene mutations that apparently contradict this rule. The corresponding beta-thalassemia genes contain nonsense mutations within exon 1, and yet their encoded mRNAs accumulate to levels approaching wild-type beta-globin (beta(WT)) mRNA. In the present report we demonstrate that the stabilities of these mRNAs with nonsense mutations in exon 1 are intermediate between beta(WT) mRNA and beta-globin mRNA carrying a prototype NMD-sensitive mutation in exon 2 (codon 39 nonsense; beta 39). Functional analyses of these mRNAs with 5'-proximal nonsense mutations demonstrate that their relative resistance to NMD does not reflect abnormal RNA splicing or translation re-initiation and is independent of promoter identity and erythroid specificity. Instead, the proximity of the nonsense codon to the translation initiation AUG constitutes a major determinant of NMD. Positioning a termination mutation at the 5' terminus of the coding region blunts mRNA destabilization, and this effect is dominant to the "50-54 nt boundary rule." These observations impact on current models of NMD.
Journal of Biological Chemistry 08/2004; 279(31):32170-80. · 4.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We explored the phylogeography of human Y-chromosomal haplogroup E3b by analyzing 3,401 individuals from five continents. Our data refine the phylogeny of the entire haplogroup, which appears as a collection of lineages with very different evolutionary histories, and reveal signatures of several distinct processes of migrations and/or recurrent gene flow that occurred in Africa and western Eurasia over the past 25,000 years. In Europe, the overall frequency pattern of haplogroup E-M78 does not support the hypothesis of a uniform spread of people from a single parental Near Eastern population. The distribution of E-M81 chromosomes in Africa closely matches the present area of distribution of Berber-speaking populations on the continent, suggesting a close haplogroup–ethnic group parallelism. E-M34 chromosomes were more likely introduced in Ethiopia from the Near East. In conclusion, the present study shows that earlier work based on fewer Y-chromosome markers led to rather simple historical interpretations and highlights the fact that many population-genetic analyses are not robust to a poorly resolved phylogeny.
The American Journal of Human Genetics 06/2004; · 11.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Homozygosity or compound heterozygosity for beta(0)-thalassemia mutations most commonly results in a transfusion-dependent thalassemia major phenotype. In this report, we describe a 55-year-old male, from Guinea-Bissau, that had been asymptomatic and never transfused until being admitted to hospital with anemia, fever, splenomegaly, and asthenia. Following hospital admission, HIV-2 and Mycobacterium tuberculosis infections were diagnosed, and biochemical and molecular studies revealed homozygosity for beta(0)-thalassemia. At the molecular level, this is the first description of homozygosity for the beta(0)-Black 1,393-bp deletion. In this case, the complete absence of beta-globin gene expression seems to be compensated by an unusually high fetal globin gene expression (Hb F 96%). Beta-globin haplotyping results were compatible with the propositus being homozygous for the Black 2 haplotype and for the absence of the XmnI polymorphism at -158 of (G)gamma-globin gene (-/-). Co-inheritance of genetic factors usually associated with high Hb F levels was not detected. Otherwise, the propositus is a heterozygote for the alpha-globin gene 3.7-kb deletion that is a beneficial modulating factor but not sufficient to explain this extremely mild phenotype. This unusual genotype/phenotype association is discussed in terms of the mechanisms underlying hemoglobin switching during development.
American Journal of Hematology 08/2002; 70(3):232-6. · 4.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The geographic origins of African slave settlers and the Portuguese genetic contribution to the population of São Tomé (Gulf of Guinea) were assessed through the analysis of beta-globin haplotypes in 44 chromosomes bearing the betaS allele and through the study of the genetic variation in eight autosomal markers (APOA1, AT3, FY, LPL, OCA2, RB1, Sb19.3, and GC) informative for admixture in a sample of 224 individuals. The observed betaS haplotype distribution (36.4% Bantu, 52.3% Benin, 4.5% Cameroon, 4.5% Senegal, and 2.3% atypical) is in accordance with the historical information on the major geographic sources of slave settlers of São Tomé, although it captures a more important contribution of Central-West Africa regions than previously anticipated. European admixture, estimated to be 10.7 +/- 0.9%, has created a considerable level of genetic structure, as indicated by the finding of significant linkage disequilibrium between 33% of unlinked marker loci pairs. Recent admixture was found to have an important contribution to these values, since removal of individuals with Portuguese or Cape Verdian parents or grandparents from the sample dropped the miscegenation level to 6.5 +/- 0.8% and reduced significant linkage disequilibrium to 11% of unlinked marker pairs. Taken together, these results indicate that the peopling of São Tomé might have provided one of the first examples of the combination of diverse African contributions and European admixture that emerged from the overseas population relocations promoted by the Atlantic slave trade.
Human Biology 07/2002; 74(3):397-411. · 1.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Haematological as well as gene mapping data are reported for three members of a Portuguese Caucasian family with high G(gamma)-globin levels. A gamma-globin gene sextuplication of the G(gamma)AG(gamma)AG(gamma)AG(gamma)AG(gamma)A(gamma) type was present in the proband and her father. Comparison of gene mapping data with quantitative results of fetal haemoglobin (HbF) analysis provided an explanation for the extremely high G(gamma)-globin levels (> 90%) in the HbF from the two mentioned individuals. This rearrangement, for which a generation mechanism is proposed, is the first gamma-globin gene sextuplication described in the literature.
British Journal of Haematology 03/2002; 116(2):454-7. · 4.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Haematological as well as gene mapping data are reported for three members of a Portuguese Caucasian family with high Gγ-globin levels. A gamma-globin gene sextuplication of the GγAGγAGγAGγAGγAγ type was present in the proband and her father. Comparison of gene mapping data with quantitative results of fetal haemoglobin (HbF) analysis provided an explanation for the extremely high Gγ-globin levels (> 90%) in the HbF from the two mentioned individuals. This rearrangement, for which a generation mechanism is proposed, is the first gamma-globin gene sextuplication described in the literature.
British Journal of Haematology 01/2002; 116(2):454-457. · 4.94 Impact Factor