Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 313
Filtrar
Mais filtros

Tipo de documento
Intervalo de ano de publicação
1.
Nature ; 605(7910): 483-489, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35585346

RESUMO

New particle formation in the upper free troposphere is a major global source of cloud condensation nuclei (CCN)1-4. However, the precursor vapours that drive the process are not well understood. With experiments performed under upper tropospheric conditions in the CERN CLOUD chamber, we show that nitric acid, sulfuric acid and ammonia form particles synergistically, at rates that are orders of magnitude faster than those from any two of the three components. The importance of this mechanism depends on the availability of ammonia, which was previously thought to be efficiently scavenged by cloud droplets during convection. However, surprisingly high concentrations of ammonia and ammonium nitrate have recently been observed in the upper troposphere over the Asian monsoon region5,6. Once particles have formed, co-condensation of ammonia and abundant nitric acid alone is sufficient to drive rapid growth to CCN sizes with only trace sulfate. Moreover, our measurements show that these CCN are also highly efficient ice nucleating particles-comparable to desert dust. Our model simulations confirm that ammonia is efficiently convected aloft during the Asian monsoon, driving rapid, multi-acid HNO3-H2SO4-NH3 nucleation in the upper troposphere and producing ice nucleating particles that spread across the mid-latitude Northern Hemisphere.

2.
Nature ; 581(7807): 184-189, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32405020

RESUMO

A list of authors and their affiliations appears at the end of the paper New-particle formation is a major contributor to urban smog1,2, but how it occurs in cities is often puzzling3. If the growth rates of urban particles are similar to those found in cleaner environments (1-10 nanometres per hour), then existing understanding suggests that new urban particles should be rapidly scavenged by the high concentration of pre-existing particles. Here we show, through experiments performed under atmospheric conditions in the CLOUD chamber at CERN, that below about +5 degrees Celsius, nitric acid and ammonia vapours can condense onto freshly nucleated particles as small as a few nanometres in diameter. Moreover, when it is cold enough (below -15 degrees Celsius), nitric acid and ammonia can nucleate directly through an acid-base stabilization mechanism to form ammonium nitrate particles. Given that these vapours are often one thousand times more abundant than sulfuric acid, the resulting particle growth rates can be extremely high, reaching well above 100 nanometres per hour. However, these high growth rates require the gas-particle ammonium nitrate system to be out of equilibrium in order to sustain gas-phase supersaturations. In view of the strong temperature dependence that we measure for the gas-phase supersaturations, we expect such transient conditions to occur in inhomogeneous urban settings, especially in wintertime, driven by vertical mixing and by strong local sources such as traffic. Even though rapid growth from nitric acid and ammonia condensation may last for only a few minutes, it is nonetheless fast enough to shepherd freshly nucleated particles through the smallest size range where they are most vulnerable to scavenging loss, thus greatly increasing their survival probability. We also expect nitric acid and ammonia nucleation and rapid growth to be important in the relatively clean and cold upper free troposphere, where ammonia can be convected from the continental boundary layer and nitric acid is abundant from electrical storms4,5.

3.
PLoS Genet ; 17(4): e1009532, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33872316

RESUMO

Recombination between the X and Y human sex chromosomes is limited to the two pseudoautosomal regions (PARs) that present quite distinct evolutionary origins. Despite the crucial importance for male meiosis, genetic diversity patterns and evolutionary dynamics of these regions are poorly understood. In the present study, we analyzed and compared the genetic diversity of the PAR regions using publicly available genomic sequences encompassing both PAR1 and PAR2. Comparisons were performed through allele diversities, linkage disequilibrium status and recombination frequencies within and between X and Y chromosomes. In agreement with previous studies, we confirmed the role of PAR1 as a male-specific recombination hotspot, but also observed similar characteristic patterns of diversity in both regions although male recombination occurs at PAR2 to a much lower extent (at least one recombination event at PAR1 and in ≈1% in normal male meioses at PAR2). Furthermore, we demonstrate that both PARs harbor significantly different allele frequencies between X and Y chromosomes, which could support that recombination is not sufficient to homogenize the pseudoautosomal gene pool or is counterbalanced by other evolutionary forces. Nevertheless, the observed patterns of diversity are not entirely explainable by sexually antagonistic selection. A better understanding of such processes requires new data from intergenerational transmission studies of PARs, which would be decisive on the elucidation of PARs evolution and their role in male-driven heterosomal aneuploidies.


Assuntos
Cromossomos Humanos X/genética , Cromossomos Humanos Y/genética , Regiões Pseudoautossômicas/genética , Recombinação Genética/genética , Mapeamento Cromossômico/métodos , Troca Genética/genética , Feminino , Frequência do Gene/genética , Ligação Genética , Humanos , Desequilíbrio de Ligação/genética , Masculino , Meiose/genética
4.
Hum Genet ; 142(12): 1651-1676, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37845370

RESUMO

Polyglutamine (polyQ) spinocerebellar ataxias (SCAs) comprise a group of autosomal dominant neurodegenerative disorders caused by (CAG/CAA)n expansions. The elongated stretches of adjacent glutamines alter the conformation of the native proteins inducing neurotoxicity, and subsequent motor and neurological symptoms. Although the etiology and neuropathology of most polyQ SCAs have been extensively studied, only a limited selection of therapies is available. Previous studies on SCA1 demonstrated that ATXN1L, a human duplicated gene of the disease-associated ATXN1, alleviated neuropathology in mice models. Other SCA-associated genes have paralogs (i.e., copies at different chromosomal locations derived from duplication of the parental gene), but their functional relevance and potential role in disease pathogenesis remain unexplored. Here, we review the protein homology, expression pattern, and molecular functions of paralogs in seven polyQ dominant ataxias-SCA1, SCA2, MJD/SCA3, SCA6, SCA7, SCA17, and DRPLA. Besides ATXN1L, we highlight ATXN2L, ATXN3L, CACNA1B, ATXN7L1, ATXN7L2, TBPL2, and RERE as promising functional candidates to play a role in the neuropathology of the respective SCA, along with the parental gene. Although most of these duplicates lack the (CAG/CAA)n region, if functionally redundant, they may compensate for a partial loss-of-function or dysfunction of the wild-type genes in SCAs. We aim to draw attention to the hypothesis that paralogs of disease-associated genes may underlie the complex neuropathology of dominant ataxias and potentiate new therapeutic strategies.


Assuntos
Proteínas Nucleares , Ataxias Espinocerebelares , Humanos , Animais , Camundongos , Ataxinas , Proteínas Nucleares/genética , Ataxina-1/genética , Proteínas do Tecido Nervoso/genética , Ataxias Espinocerebelares/genética , Ataxia , Proteínas Semelhantes à Proteína de Ligação a TATA-Box
5.
Hum Genet ; 142(12): 1747-1754, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37957369

RESUMO

Machado-Joseph disease (MJD/SCA3) is the most frequent dominant ataxia worldwide. It is caused by a (CAG)n expansion. MJD has two major ancestral backgrounds: the Machado lineage, found mainly in Portuguese families; and the Joseph lineage, present in all five continents, probably originating in Asia. MJD has been described in a few African and African-American families, but here we report the first diagnosed in Sudan to our knowledge. The proband presented with gait ataxia at age 24; followed by muscle cramps and spasticity, and dysarthria, by age 26; he was wheel-chair bound at 29 years of age. His brother had gait problems from age 20 years and, by age 21, lost the ability to run, showed dysarthria and muscle cramps. To assess the mutational origin of this family, we genotyped 30 SNPs and 7 STRs flanking the ATXN3_CAG repeat in three siblings and the non-transmitting father. We compared the MJD haplotype segregating in the family with our cohort of MJD families from diverse populations. Unlike all other known families of African origin, the Machado lineage was observed in Sudan, being shared with 86 Portuguese, 2 Spanish and 2 North-American families. The STR-based haplotype of Sudanese patients, however, was distinct, being four steps (2 STR mutations and 2 recombinations) away from the founder haplotype shared by 47 families, all of Portuguese extraction. Based on the phylogenetic network constructed with all MJD families of the Machado lineage, we estimated a common ancestry at 3211 ± 693 years ago.


Assuntos
Doença de Machado-Joseph , Masculino , Humanos , Adulto Jovem , Adulto , Doença de Machado-Joseph/genética , Doença de Machado-Joseph/diagnóstico , Portugal , Cãibra Muscular , Disartria , Filogenia , África Oriental
6.
Environ Sci Technol ; 56(19): 13931-13944, 2022 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-36137236

RESUMO

Dimethyl sulfide (DMS) influences climate via cloud condensation nuclei (CCN) formation resulting from its oxidation products (mainly methanesulfonic acid, MSA, and sulfuric acid, H2SO4). Despite their importance, accurate prediction of MSA and H2SO4 from DMS oxidation remains challenging. With comprehensive experiments carried out in the Cosmics Leaving Outdoor Droplets (CLOUD) chamber at CERN, we show that decreasing the temperature from +25 to -10 °C enhances the gas-phase MSA production by an order of magnitude from OH-initiated DMS oxidation, while H2SO4 production is modestly affected. This leads to a gas-phase H2SO4-to-MSA ratio (H2SO4/MSA) smaller than one at low temperatures, consistent with field observations in polar regions. With an updated DMS oxidation mechanism, we find that methanesulfinic acid, CH3S(O)OH, MSIA, forms large amounts of MSA. Overall, our results reveal that MSA yields are a factor of 2-10 higher than those predicted by the widely used Master Chemical Mechanism (MCMv3.3.1), and the NOx effect is less significant than that of temperature. Our updated mechanism explains the high MSA production rates observed in field observations, especially at low temperatures, thus, substantiating the greater importance of MSA in the natural sulfur cycle and natural CCN formation. Our mechanism will improve the interpretation of present-day and historical gas-phase H2SO4/MSA measurements.

7.
Nature ; 533(7604): 521-6, 2016 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-27225125

RESUMO

Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere, and that ions have a relatively minor role. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of α-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported by quantum chemical calculations of the cluster binding energies of representative HOMs. Ion-induced nucleation of pure organic particles constitutes a potentially widespread source of aerosol particles in terrestrial environments with low sulfuric acid pollution.


Assuntos
Aerossóis/química , Atmosfera/química , Mudança Climática , Íons/química , Oxigênio/química , Material Particulado/química , Poluição do Ar/análise , Monoterpenos Bicíclicos , Radiação Cósmica , Atividades Humanas , Monoterpenos/química , Oxirredução , Ozônio/química , Tamanho da Partícula , Teoria Quântica , Ácidos Sulfúricos/análise , Volatilização
8.
Hemoglobin ; 46(3): 168-175, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35635444

RESUMO

In the already identified quantitative trait loci (QTL), modulating Hb F levels are cis-acting haplotypes of the ß-globin gene cluster itself, although the single nucleotide polymorphisms (SNPs) accounting more for the association, remain uncertain. In this study, the role in Hb F production of previously reported candidate SNPs within the ß-globin gene cluster was reexamined, along with a yet poorly studied variation in the BGLT3 gene. In a sample of ß-thalassemia (ß-thal) carriers, we succeeded in replicating the significant association between increased Hb F levels and rs7482144 (C>T) (HBG2 XmnI), which is the most well-established variation in the cluster influencing the trait. This SNP was found to be in strong linkage disequilibrium (LD) with a variation in the HBBP1 gene [rs10128556 (G>A)], which consistently revealed a similar association signal. Remarkably, much stronger than the latter associations were those involving both rs968857 (T allele) (3' HBBP1) and rs7924684 (G allele) (BGLT3), two SNPs that were also in strong LD. As the pattern of LD detected in the ß-globin gene cluster does not correlate with a tight linkage between markers, complex interactions between SNPs at the cluster seem to modulate Hb F. Seeing that no such associations were detected in normal subjects, the question can be raised on whether, under erythropoiesis stress, epigenetic mechanisms contribute to change the regulation of the entire ß-globin gene cluster. In conclusion, we provide statistical evidence for a new player within the ß-globin gene cluster, BGLT3, that in cooperation with other regions influences Hb F levels in ß-thal carriers.


Assuntos
Globinas beta , Talassemia beta , Proteínas de Transporte/genética , Hemoglobina Fetal/genética , Humanos , Família Multigênica , Locos de Características Quantitativas , Globinas beta/genética , Talassemia beta/genética
9.
Hum Mutat ; 42(8): 978-989, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34015158

RESUMO

Understanding the role of common polymorphisms in modulating the clinical phenotype when they co-occur with a disease-causing lesion is of critical importance in medical genetics. We explored the impact of apparently neutral common polymorphisms, using the gene encoding the urea cycle enzyme, ornithine transcarbamylase (OTC), as a model system. Distinct combinations of genetic backgrounds embracing two missense polymorphisms were created in cis with the pathogenic p.Arg40His replacement. In vitro enzymatic assays revealed that the polymorphic variants were able to modulate OTC activity both in the presence or absence of the pathogenic lesion. First, we found that the combination of the minor alleles of polymorphisms p.Lys46Arg and p.Gln270Arg significantly enhanced enzymatic activity in the wild-type protein. Second, enzymatic assays revealed that the minor allele of the p.Gln270Arg polymorphism was capable of ameliorating OTC activity when combined in cis with the pathogenic p.Arg40His replacement. Structural analysis predicted that the minor allele of the p.Gln270Arg polymorphism would serve to stabilize the OTC wild-type protein, thereby corroborating the results of the experimental assays. Our findings demonstrate the potential importance of cis-interactions between common polymorphic variants and pathogenic missense mutations and illustrate how standing genetic variation can modulate protein function.


Assuntos
Doença da Deficiência de Ornitina Carbomoiltransferase , Ornitina Carbamoiltransferase , Alelos , Humanos , Mutação de Sentido Incorreto , Ornitina Carbamoiltransferase/genética , Doença da Deficiência de Ornitina Carbomoiltransferase/genética , Polimorfismo Genético
10.
Hum Genet ; 140(9): 1329-1342, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34173867

RESUMO

A non-negligible proportion of human pathogenic variants are known to be present as wild type in at least some non-human mammalian species. The standard explanation for this finding is that molecular mechanisms of compensatory epistasis can alleviate the mutations' otherwise pathogenic effects. Examples of compensated variants have been described in the literature but the interacting residue(s) postulated to play a compensatory role have rarely been ascertained. In this study, the examination of five human X-chromosomally encoded proteins (FIX, GLA, HPRT1, NDP and OTC) allowed us to identify several candidate compensated variants. Strong evidence for a compensated/compensatory pair of amino acids in the coagulation FIXa protein (involving residues 270 and 271) was found in a variety of mammalian species. Both amino acid residues are located within the 60-loop, spatially close to the 39-loop that performs a key role in coagulation serine proteases. To understand the nature of the underlying interactions, molecular dynamics simulations were performed. The predicted conformational change in the 39-loop consequent to the Glu270Lys substitution (associated with hemophilia B) appears to impair the protein's interaction with its substrate but, importantly, such steric hindrance is largely mitigated in those proteins that carry the compensatory residue (Pro271) at the neighboring amino acid position.


Assuntos
Cromossomos Humanos X/genética , Epistasia Genética , Fator IXa , Simulação de Dinâmica Molecular , Mutação de Sentido Incorreto , Substituição de Aminoácidos , Fator IXa/química , Fator IXa/genética , Humanos
11.
Proc Natl Acad Sci U S A ; 115(37): 9122-9127, 2018 09 11.
Artigo em Inglês | MEDLINE | ID: mdl-30154167

RESUMO

Nucleation and growth of aerosol particles from atmospheric vapors constitutes a major source of global cloud condensation nuclei (CCN). The fraction of newly formed particles that reaches CCN sizes is highly sensitive to particle growth rates, especially for particle sizes <10 nm, where coagulation losses to larger aerosol particles are greatest. Recent results show that some oxidation products from biogenic volatile organic compounds are major contributors to particle formation and initial growth. However, whether oxidized organics contribute to particle growth over the broad span of tropospheric temperatures remains an open question, and quantitative mass balance for organic growth has yet to be demonstrated at any temperature. Here, in experiments performed under atmospheric conditions in the Cosmics Leaving Outdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN), we show that rapid growth of organic particles occurs over the range from [Formula: see text]C to [Formula: see text]C. The lower extent of autoxidation at reduced temperatures is compensated by the decreased volatility of all oxidized molecules. This is confirmed by particle-phase composition measurements, showing enhanced uptake of relatively less oxygenated products at cold temperatures. We can reproduce the measured growth rates using an aerosol growth model based entirely on the experimentally measured gas-phase spectra of oxidized organic molecules obtained from two complementary mass spectrometers. We show that the growth rates are sensitive to particle curvature, explaining widespread atmospheric observations that particle growth rates increase in the single-digit-nanometer size range. Our results demonstrate that organic vapors can contribute to particle growth over a wide range of tropospheric temperatures from molecular cluster sizes onward.

12.
Hum Genomics ; 13(1): 31, 2019 07 09.
Artigo em Inglês | MEDLINE | ID: mdl-31288856

RESUMO

Neurodevelopmental disorders (NDDs) represent a growing medical challenge in modern societies. Ever-increasing sophisticated diagnostic tools have been continuously revealing a remarkably complex architecture that embraces genetic mutations of distinct types (chromosomal rearrangements, copy number variants, small indels, and nucleotide substitutions) with distinct frequencies in the population (common, rare, de novo). Such a network of interacting players creates difficulties in establishing rigorous genotype-phenotype correlations. Furthermore, individual lifestyles may also contribute to the severity of the symptoms fueling a large spectrum of gene-environment interactions that have a key role on the relationships between genotypes and phenotypes.Herein, a review of the genetic discoveries related to NDDs is presented with the aim to provide useful general information for the medical community.


Assuntos
Variações do Número de Cópias de DNA/genética , Predisposição Genética para Doença , Transtornos do Neurodesenvolvimento/genética , Interação Gene-Ambiente , Estudos de Associação Genética , Genótipo , Humanos , Mutação/genética , Transtornos do Neurodesenvolvimento/patologia
13.
Environ Sci Technol ; 54(13): 7911-7921, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32515954

RESUMO

To better understand the role of aromatic hydrocarbons in new-particle formation, we measured the particle-phase abundance and volatility of oxidation products following the reaction of aromatic hydrocarbons with OH radicals. For this we used thermal desorption in an iodide-adduct Time-of-Flight Chemical-Ionization Mass Spectrometer equipped with a Filter Inlet for Gases and AEROsols (FIGAERO-ToF-CIMS). The particle-phase volatility measurements confirm that oxidation products of toluene and naphthalene can contribute to the initial growth of newly formed particles. Toluene-derived (C7) oxidation products have a similar volatility distribution to that of α-pinene-derived (C10) oxidation products, while naphthalene-derived (C10) oxidation products are much less volatile than those from toluene or α-pinene; they are thus stronger contributors to growth. Rapid progression through multiple generations of oxidation is more pronounced in toluene and naphthalene than in α-pinene, resulting in more oxidation but also favoring functional groups with much lower volatility per added oxygen atom, such as hydroxyl and carboxylic groups instead of hydroperoxide groups. Under conditions typical of polluted urban settings, naphthalene may well contribute to nucleation and the growth of the smallest particles, whereas the more abundant alkyl benzenes may overtake naphthalene once the particles have grown beyond the point where the Kelvin effect strongly influences the condensation driving force.


Assuntos
Hidrocarbonetos Aromáticos , Compostos Orgânicos Voláteis , Aerossóis , Gases , Volatilização
14.
PLoS Genet ; 13(9): e1006960, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28934201

RESUMO

While traditional forensic genetics has been oriented towards using human DNA in criminal investigation and civil court cases, it currently presents a much wider application range, including not only legal situations sensu stricto but also and, increasingly often, to preemptively avoid judicial processes. Despite some difficulties, current forensic genetics is progressively incorporating the analysis of nonhuman genetic material to a greater extent. The analysis of this material-including other animal species, plants, or microorganisms-is now broadly used, providing ancillary evidence in criminalistics in cases such as animal attacks, trafficking of species, bioterrorism and biocrimes, and identification of fraudulent food composition, among many others. Here, we explore how nonhuman forensic genetics is being revolutionized by the increasing variety of genetic markers, the establishment of faster, less error-burdened and cheaper sequencing technologies, and the emergence and improvement of models, methods, and bioinformatics facilities.


Assuntos
Bactérias/genética , Genética Forense/tendências , Genômica , Animais , Biologia Computacional/tendências , Análise de Alimentos , Marcadores Genéticos , Humanos , Plantas/genética
15.
Nature ; 502(7471): 359-63, 2013 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-24097350

RESUMO

Nucleation of aerosol particles from trace atmospheric vapours is thought to provide up to half of global cloud condensation nuclei. Aerosols can cause a net cooling of climate by scattering sunlight and by leading to smaller but more numerous cloud droplets, which makes clouds brighter and extends their lifetimes. Atmospheric aerosols derived from human activities are thought to have compensated for a large fraction of the warming caused by greenhouse gases. However, despite its importance for climate, atmospheric nucleation is poorly understood. Recently, it has been shown that sulphuric acid and ammonia cannot explain particle formation rates observed in the lower atmosphere. It is thought that amines may enhance nucleation, but until now there has been no direct evidence for amine ternary nucleation under atmospheric conditions. Here we use the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber at CERN and find that dimethylamine above three parts per trillion by volume can enhance particle formation rates more than 1,000-fold compared with ammonia, sufficient to account for the particle formation rates observed in the atmosphere. Molecular analysis of the clusters reveals that the faster nucleation is explained by a base-stabilization mechanism involving acid-amine pairs, which strongly decrease evaporation. The ion-induced contribution is generally small, reflecting the high stability of sulphuric acid-dimethylamine clusters and indicating that galactic cosmic rays exert only a small influence on their formation, except at low overall formation rates. Our experimental measurements are well reproduced by a dynamical model based on quantum chemical calculations of binding energies of molecular clusters, without any fitted parameters. These results show that, in regions of the atmosphere near amine sources, both amines and sulphur dioxide should be considered when assessing the impact of anthropogenic activities on particle formation.


Assuntos
Aminas/química , Atmosfera/química , Material Particulado/química , Ácidos Sulfúricos/química , Radiação Cósmica , Dimetilaminas/química , Efeito Estufa , Atividades Humanas , Modelos Químicos , Teoria Quântica , Dióxido de Enxofre/química
16.
Proc Natl Acad Sci U S A ; 113(43): 12053-12058, 2016 10 25.
Artigo em Inglês | MEDLINE | ID: mdl-27790989

RESUMO

The magnitude of aerosol radiative forcing caused by anthropogenic emissions depends on the baseline state of the atmosphere under pristine preindustrial conditions. Measurements show that particle formation in atmospheric conditions can occur solely from biogenic vapors. Here, we evaluate the potential effect of this source of particles on preindustrial cloud condensation nuclei (CCN) concentrations and aerosol-cloud radiative forcing over the industrial period. Model simulations show that the pure biogenic particle formation mechanism has a much larger relative effect on CCN concentrations in the preindustrial atmosphere than in the present atmosphere because of the lower aerosol concentrations. Consequently, preindustrial cloud albedo is increased more than under present day conditions, and therefore the cooling forcing of anthropogenic aerosols is reduced. The mechanism increases CCN concentrations by 20-100% over a large fraction of the preindustrial lower atmosphere, and the magnitude of annual global mean radiative forcing caused by changes of cloud albedo since 1750 is reduced by [Formula: see text] (27%) to [Formula: see text] Model uncertainties, relatively slow formation rates, and limited available ambient measurements make it difficult to establish the significance of a mechanism that has its dominant effect under preindustrial conditions. Our simulations predict more particle formation in the Amazon than is observed. However, the first observation of pure organic nucleation has now been reported for the free troposphere. Given the potentially significant effect on anthropogenic forcing, effort should be made to better understand such naturally driven aerosol processes.


Assuntos
Aerossóis/análise , Atmosfera/análise , Modelos Estatísticos , Aerossóis/química , Poluentes Atmosféricos/análise , Poluentes Atmosféricos/química , Atmosfera/química , Clima , Simulação por Computador , História do Século XVIII , História do Século XIX , História do Século XX , História do Século XXI , Humanos , Desenvolvimento Industrial/história , Incerteza
17.
Hemoglobin ; 43(3): 149-154, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31394941

RESUMO

Mutations on the HBB gene are a common cause of hemoglobinopathies, including sickle cell anemia, a severe genetic condition that constitutes a major public health concern. The aim of this study was to determine the prevalence of sickle cell anemia and ß-globin haplotype distribution in newborns from the Bengo region. The first two exons of ß-globin gene were sequenced, and the variability at the single nucleotide polymorphism (SNP) defining the Hb S (HBB: c.20A>T) haplotypes, was analyzed by a SNaPshot® Multiplex system. About 3.3% of the children were homozygous for Hb S, and 82.2% had as background the Bantu/Central African Republic (BAN/CAR) haplotype, 11.2% the Benin (BEN) and 6.6% the Senegal (SEN). The estimate of Hb S reached the very high value of 0.1476 ± 0.0133, with the aggravating factor of 82.2% of the sickle alleles being anchored in the BAN/CAR haplotype, associated with the more severe sickle cell anemia phenotypes. Also, the high prevalence of the SEN haplotype was not expected, having therapeutic consequences since is associated with more severe outcomes. In addition, two ß-thalassemia (ß-thal) variants were also detected, IVS I-110 (G>A) (HBB: c.93-21G>A) and codon 39 (C>T) (HBB: c.118C>T), together totaling a frequency of 1.3%. Some of the newborns with these mutations were compound heterozygotes for Hb S, likely carrying genotypes consistent with sickle cell disease. As a whole, infants molecularly diagnosed with sickle cell disease accounted for 4.5% of newborns from Bengo, Angola, a figure that per se, highlights the urgent need of implementing policies warranting surveillance of these children, in parallel with community education in the region.


Assuntos
Anemia Falciforme/epidemiologia , Anemia Falciforme/genética , Variação Genética , Haplótipos , Globinas beta/genética , Alelos , Anemia Falciforme/diagnóstico , Angola/epidemiologia , Feminino , Frequência do Gene , Estudos de Associação Genética , Genética Populacional , Hemoglobina Falciforme/genética , Humanos , Masculino , Programas de Rastreamento , Fenótipo , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA
18.
Mol Biol Evol ; 34(12): 3232-3242, 2017 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-29029191

RESUMO

During the Neolithic, human populations underwent cultural and technological developments that led to an agricultural revolution. Although the population genetics and evolution of European Neolithic populations have been extensively studied, little is known regarding the Neolithic expansion in North Africa with respect to Europe. One could expect that the different environmental and geological conditions at both shores of the Mediterranean Sea could have led to contrasting expansions. In order to test this hypothesis, we compared the Neolithic expansion in Europe and North Africa accounting for possible migration between them through the Strait of Gibraltar. We analyzed the entire X chromosome of 580 individuals from 20 populations spatially distributed along the North of Africa and Europe. Next, we applied approximate Bayesian computation based on extensive spatially explicit computer simulations to select among alternative scenarios of migration through the Strait of Gibraltar and to estimate population genetics parameters in both expansions. Our results suggest that, despite being more technologically advanced, Neolithic populations did not expand faster than Paleolithic populations, which could be interpreted as a consequence of a more sedentary lifestyle. We detected reciprocal Neolithic migration between the Iberian Peninsula and North Africa through the Strait of Gibraltar. Counterintuitively, we found that the studied Neolithic expansions presented similar levels of carrying capacity and migration, and occurred at comparable speeds, suggesting a similar demic process of substitution of hunter-gatherer populations. Altogether, the Neolithic expansion through both Mediterranean shores was not so different, perhaps because these populations shared similar technical abilities and lifestyle patterns.


Assuntos
Cromossomos Humanos X/genética , Etnicidade/genética , África do Norte/etnologia , Teorema de Bayes , População Negra/genética , DNA Mitocondrial/genética , Europa (Continente)/etnologia , Frequência do Gene , Variação Genética , Genética Populacional/métodos , Humanos , Mar Mediterrâneo/etnologia , Modelos Genéticos , Dinâmica Populacional , População Branca/genética
20.
Appl Microbiol Biotechnol ; 102(24): 10377-10391, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30302518

RESUMO

Recent advances in genetic data generation, through massive parallel sequencing (MPS), storage and analysis have fostered significant progresses in microbial forensics (or forensic microbiology). Initial applications in circumstances of biocrime, bioterrorism and epidemiology are now accompanied by the prospect of using microorganisms (i) as ancillary evidence in criminal cases; (ii) to clarify causes of death (e.g., drownings, toxicology, hospital-acquired infections, sudden infant death and shaken baby syndromes); (iii) to assist human identification (skin, hair and body fluid microbiomes); (iv) for geolocation (soil microbiome); and (v) to estimate postmortem interval (thanatomicrobiome and epinecrotic microbial community). When compared with classical microbiological methods, MPS offers a diverse range of advantages and alternative possibilities. However, prior to its implementation in the forensic context, critical efforts concerning the elaboration of standards and guidelines consolidated by the creation of robust and comprehensive reference databases must be undertaken.


Assuntos
Ciências Forenses/métodos , Técnicas Microbiológicas/métodos , Microbiota , Causas de Morte , Infecção Hospitalar/microbiologia , Afogamento/microbiologia , Toxicologia Forense/métodos , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Recém-Nascido , Mudanças Depois da Morte , Síndrome do Bebê Sacudido/microbiologia , Microbiologia do Solo , Morte Súbita do Lactente
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA