Associação do perfil de acetilação lenta do gene NAT2 na susceptibilidade ao câncer, na Região Norte do Brasil

Objetivos: O gene N-acetiltransferase 2 (NAT2) é um marcador para o estudo da susceptibilidade interindividual ao desenvolvimento de neoplasias malignas, visto que a enzima NAT2 participa da metabolização de agentes carcinogênicos e os polimorfismos de base única (SNP) do seu gene produzem enzimas com diferentes atividades, levando a acetilação lenta ou rápida de xenobióticos. O objetivo do presente estudo foi verificar uma possível associação entre os SNPS do gene NAT2 e a susceptibilidade ao acometimento de Adenocarcinoma gástrico ou Carcinoma ductal invasivo da mama em pacientes da região norte do Brasil. Material e Métodos: Os cinco polimorfismos de grande importância para a determinação do perfil de metabolização da enzima NAT2 (C282T, T341 C, C481 T, A803G e G857A) foram investigados por sequenciamento direto de 986 pares de bases, amplificados em duas reações de PCR, no total de 133 pacientes com câncer (63 com Câncer Gástrico e 70 com Câncer de Mama) e 89 indivíduos Controles. Para evitar interpretações espúrias decorrentes do subestruturamento populacional, empregamos um painel de 48 marcadores informativos de ancestralidade (IAM). Resultados: Encontramos diferenças estatísticas para a contribuição parental Africana e Européia, quando comparadas entre os grupos com Câncer e Controles, uma contribuição maior do grupo Africano foi detectada no grupo de estudo com câncer e, no grupo controle, foi detectada uma maior contribuição do grupo Europeu (p<0,001). Os genótipos do polimorfismo C282T dominante (TT + CT) apresentaram associação significativa (p<0,001; OR 3,076; Cl 95% 1,664-5,687) para a susceptibilidade as diferentes formas de Câncer investigadas. Foi observada uma associação significante do perfil de acetilação lenta e rápida com a susceptibilidade ao desenvolvimento das neoplasias investigadas (p=0,010; OR 3,054; Cl 95% 1,303-7,159) e (p= 0,041; OR 0,527 Cl 95% 0,280-0,973) evidenciando que indivíduos com o perfil acetilador lento apresentaram um risco aumentado em até três vezes no desenvolvimento de neoplasias quando comparado com os indivíduos controles. Conclusão: O controle genômico da ancestralidade foi efetivamente importante para a presente investigação possibilitando controlar o efeito da ancestralidade na associação do gene NAT2 para susceptibilidade ao câncer. Neste trabalho foi possivel evidenciar a forte influência do perfil de acetilação lenta do gene NAT2 de xenobióticos na susceptibilidade ao Câncer Gástrico e de Mama.

Does ethnic ancestry play a role in smoking?

A maior proporção de fumantes entre negros no Brasil tem sido atribuída a desigualdades socioeconômicas, mas fatores genéticos também poderiam contribuir para esse achado. Este estudo visou investigar associações entre status tabágico com ancestralidade definida geneticamente e características socioeconômicas em brasileiros. Amostras de sangue foram colhidas de 448 voluntários (66,7% homens; idade: 37,1±11,4 anos) classificados como fumantes atuais (FA: 60,9%), ex-fumantes (EF:8,9%) e não fumantes (NF:30,1%).Misturas éticas individuais foram determinadas empregando-se um painel informativo de ancestralidade composto por 48 polimorfismos de deleções e inserções. FA mostraram menor proporção de ancestralidade europeia do que NF (0,837±0,243 X 0,883±0,194; p≤0,05) e EF (0,837±0,243 X 0,864±0,230; p≤0,05), e maior proporção de ancestralidade africana sub-saárica do que EF (0,128±0,222 X 0,07±0,174, p≤0,05) e NF (0,128±0,222 X 0,085±0,178, p≤0,05). NF informaram maior número de anos de escola do que FA (11,2±3,7 X 8,9±3,8; p≤0,001). FA foram menos comuns na Classe econômica A (30%) e mais comuns na Classe B (56,8%). Em análise multivariada, apenas menor número de anos escolares e menor classe econômica estiveram associados com chances maiores para FA. O uso de marcadores de genética molecular para caracterizar o background étnico confirmou que diferenças socioeconômicas são os principais determinantes de maiores taxas de tabagismo entre negros no Brasil.

Genetic variability and efficiency of DNA microsatellite markers for paternity testing in horse breeds from the Brazilian Marajó archipelago

In this study, 15 microsatellite DNA loci used in comparative tests by the International Society for Animal Genetics were applied to the evaluation of genetic diversity and management, and the efficiency of paternity testing in Marajoara horses and Puruca ponies from the Marajó Archipelago. Based on the genotyping of 93 animals, mean allelic diversity was estimated as 9.14 and 7.00 for the Marajoara and Puruca breeds, respectively. While these values are similar to those recorded in most European breeds, mean levels of heterozygosity were much lower (Marajoara 49%, Puruca 40%), probably as a result of high levels of inbreeding in the Marajó populations. The mean informative polymorphic content of this 15-marker system was over 50% in both breeds, and was slightly higher in the Marajoara horses. The discriminative power and exclusion probabilities derived from this system were over 99% for both populations, emphasizing the efficacy of these markers for paternity testing and genetic management in the two breeds.

Genetical-demographic data from two amazonian populations composed of descendants of african slaves: Pacoval and Curiau

The Amazon region of Brazil includes communities founded by escaped slaves, some of which still remain relatively isolated. We studied two such Afro-Brazilian communities (Pacoval and Curiau), in the rural area of Alenquer, Pará, and in the metropolitan region of Macapá, Amapá, respectively. Among 12 blood loci, alleles considered as markers of African ancestry, such as HBB*S, HBB*C, TF*D1, HP*2M, ABO*B, RH*D-, and CA2*2 were found at frequencies that are expected for populations with a predominantly African origin. Estimates of interethnic admixture indicated that the degree of the African component in Curiau (74%) is higher than that of Pacoval (44%); an Amerindian contribution was not detected in Curiau. Estimated values of African ancestry fit well with the degree of isolation and mobility of the communities. Pacoval exhibited a high proportion of immigrants among the parents and grandparents of the individuals studied, whereas persons living in Curiau exhibited a low level of mobility, despite its location in the metropolitan area of Macapá city, suggesting a relatively strong barrier against the interethnic admixture in this population. In addition, analysis of genetic data in a sub-sample consisting of individuals whose parents and grandparents were born in the study site, and that probably represents the populations two generations ago, indicated that gene flow from non-black people is not a recent event in both populations.

Association of killer cell immunoglobulin-like receptor polymorphisms with chronic hepatitis C and responses to therapy in Brazil

ABSTRACT: Soroprevalence for Hepatitis C virus is reported as 2.12% in Northern Brazil, with about 50% of the patients exhibiting a sustained virological response (SVR). Aiming to associate polymorphisms in Killer Cell Immunoglobulin-like Receptors (KIR) with chronic hepatitis C and therapy responses we investigated 125 chronic patients and 345 controls. Additionally, 48 ancestry markers were genotyped to control for population stratification. The frequency of the KIR2DL2 and KIR2DL2+HLA-C^Asp80 gene and ligand was higher in chronic infected patients than in controls (p < 0.0009, OR = 3.4; p = 0.001, OR = 3.45). In fact, KIR2DL3 is a weaker inhibitor of NK activity than KIR2DL2, which could explain the association of KIR2DL2 with chronic infection. Moreover, KIR2DS2 and KIR2DS2+HLA-C^Asp80 (p < 0.0001, OR = 2.51; p = 0.0084, OR = 2.62) and KIR2DS3 (p < 0.0001; OR = 2.57) were associated with chronic infection, independently from KIR2DL2. No differences in ancestry composition were observed between control and patients, even with respect to therapy response groups. The allelic profile KIR2DL2/KIR2DS2/KIR2DS3 was associated with the chronic hepatitis C (p < 0.0001; OR = 3). Furthermore, the patients also showed a higher mean number of activating genes and a lower frequency of the homozygous AA profile, which is likely secondary to the association with non-AA and/or activating genes. In addition, the KIR2DS5 allele was associated with SVR (p = 0.0261; OR = 0.184).The ancestry analysis of samples ruled out any effects of population substructuring and did not evidence interethnic differences in therapy response, as suggested in previous studies.

Molecular analysis of three FUT3 gene single nucleotide polymorphisms and their relationship with the lewis erythrocytary phenotype in a human population of japanese-ancestry living in Tomé Açu, a town in the Brazilian Amazon

The Lewis blood group system involves two major antigens, Le^ª and Le^b. Their antigenic determinants are not primary gene products but are synthesized by the transfer of sugar subunits to a precursory chain by a specific enzyme which is the product of the FUT3 gene (Lewis gene). The presence of three FUT3 gene single nucleotide polymorphisms (SNPs) (59T > G; 508G > A and 1067T > A) was related to the Lewis phenotype of erythrocytes from 185 individuals of Japanese ancestry living in the town of Tomé-Açu in the Brazilian Amazon region. This relationship was detected using a serological hemagglutination test and the Dot-ELISA assay along with the molecular technique PCR-RFLP. We found that the three SNPs investigated in this study only accounted for a proportion of the Lewis-negative phenotype of the erythrocytes.

Identification of duplicates of cassava accessions sampled on the North Region of Brazil using microsatellite markers

Duplicatas costumam ocorrer em bancos de germoplasma e a sua identificação é necessária para facilitar o manejo dos bancos ativos de germoplasma (BAGs) e diminuir custos de manutenção. O objetivo deste trabalho foi identificar duplicatas de mandioca determinadas previamente pela caracterização morfo-agronômica, em um BAG da Amazônia Oriental. Foram selecionados 36 acessos que se agrupavam em 13 grupos de similaridade morfo-agronômica para serem genotipados com 15 locos microssatélites. Todos os locos foram polimórficos, sendo obtidos 75 alelos, com média de cinco alelos por loco e H_E = 0,66. Foram encontrados 34 pares de genótipos que apresentaram perfis multilocos idênticos e a probabilidade de identidade genética foi de 1,1x10^-12 com probabilidade de exclusão de 99,9999%. Entre essas duplicatas, estão materiais coletados em épocas e locais diferentes, e com diferentes denominações e acessos com o mesmo nome coletados em diferentes locais e anos. O estudo identificou genótipos que vem sendo cultivados em diferentes locais e que vêm sendo mantidos pelos agricultores ao longo dos anos.

Assessing the genetic structure of Oryza glumaepatula populations with isozyme markers

To assess the genetic diversity and genetic structure parameters, nine populations of Oryza glumaepatula from the Amazon biome, four from the Pantanal biome, and one collected at Rio Xingu, Mato Grosso, totaling 14 populations and 333 individuals were studied with isozyme markers. Six loci were evaluated showing a moderate allozyme variability (A = 1.21, P = 20.7%, H_o = 0.005, H_e = 0.060). The populations from the Pantanal biome showed higher diversity levels than the Amazon biome. High genetic differentiation among the populations, expected for self-fertilizing species, was observed (F_ST=0.763), with lower differentiation found among the Pantanal populations (F_ST=0.501). The average apparent outcrossing rate was higher for the Pantanal populations (t _a = 0.092) than for the Amazonian populations (t _a = 0.003), while the average for the 14 populations was 0.047, in accordance with a self-fertilization mating system.

Genetic identification of bucktooth parrotfish Sparisoma radians (Valenciennes, 1840) (Labridae, Scarinae) by chromosomal and molecular markers

Parrotfishes (Labridae, Scarinae) comprise a large marine fish group of difficult identification, particularly during juvenile phase when the typical morphology and coloration of adults are absent. Therefore, the goal of this study was to test cytogenetic markers and DNA barcoding in the identification of bucktooth parrtotfish Sparisoma radians from the northeastern coast of Brazil. Sequencing of cytochrome c oxidase subunit I (COI) confirmed all studied samples as S. radians, and all showed high similarity (99-100%) with Caribbean populations. The karyotype of this species was divergent from most marine Perciformes, being composed of 2n = 46 chromosomes. These consisted of a large number of metacentric and submetacentric pairs with small amounts of heterochromatin and GC-rich single nucleolar organizer regions (NORs) not syntenic to 5S rDNA clusters. These are the first data about DNA barcoding in parrotfish from the Brazilian province and the first refined chromosomal analysis in Scarinae, providing useful data to a reliable genetic identification of S. radians.

Molecular analysis of three FUT3 gene single nucleotide polymorphisms and their relationship with the lewis erythrocytary phenotype in a human population of japanese-ancestry living in Tomé Açu, a town in the Brazilian Amazon

The Lewis blood group system involves two major antigens, Le^a and Le^b. Their antigenic determinants are not primary gene products but are synthesized by the transfer of sugar subunits to a precursory chain by a specific enzyme which is the product of the FUT3 gene (Lewis gene). The presence of three FUT3 gene single nucleotide polymorphisms (SNPs) (59T > G; 508G > A and 1067T > A) was related to the Lewis phenotype of erythrocytes from 185 individuals of Japanese ancestry living in the town of Tomé-Açu in the Brazilian Amazon region. This relationship was detected using a serological hemagglutination test and the Dot-ELISA assay along with the molecular technique PCR-RFLP. We found that the three SNPs investigated in this study only accounted for a proportion of the Lewis-negative phenotype of the erythrocytes.

A comparison of molecular markers to detect Lutzomyia longipalpis naturally infected with Leishmania (Leishmania) infantum

The aim of the present study was to detect natural infection by Leishmania (Leishmania) infantum in Lutzomyia longipalpis captured in Barcarena, state of Pará, Brazil, through the use of three primer sets. With this approach, it is unnecessary to previously dissect the sandfly specimens. DNA of 280 Lu. longipalpis female specimens were extracted from the whole insects. PCR primers for kinetoplast minicircle DNA (kDNA), the mini-exon gene and the small subunit ribosomal RNA (SSU-rRNA) gene of Leishmania were used, generating fragments of 400 bp, 780 bp and 603 bp, respectively. Infection by the parasite was found with the kDNA primer in 8.6% of the cases, with the mini-exon gene primer in 7.1% of the cases and with the SSU-rRNA gene primer in 5.3% of the cases. These data show the importance of polymerase chain reaction as a tool for investigating the molecular epidemiology of visceral leishmaniasis by estimating the risk of disease transmission in endemic areas, with the kDNA primer representing the most reliable marker for the parasite.