RESUMO
Species belonging to the Leishmania (Viannia) subgenus are important causative agents of cutaneous and mucocutaneous leishmaniasis in Central and South America. These parasites possess several distinctive biological features that are influenced by their genetics, population structure, and genome instability. To date, several studies have revealed varying degrees of genetic diversity within Leishmania species. Particularly, in species of the L. (Viannia) subgenus, a generalized high intraspecific genetic diversity has been reported, although, conflicting conclusions have been drawn using different molecular techniques. Despite being the most common Leishmania species circulating in Panama and Colombia, few studies have analyzed clinical samples of Leishmania panamensis using whole-genome sequencing, and their restricted number of samples has limited the information they can provide to understand the population structure of L. panamensis. Here, we used next generation sequencing (NGS) to explore the genetic diversity of L. panamensis within its endemic range, analyzing data from 43 isolates of Colombian and Panamanian origin. Our results show the occurrence of three well-defined geographically correlated groups, and suggests the possible occurrence of additional phylogeographic groups. Furthermore, these results support the existence of a mixed mode of reproduction in L. panamensis, with varying frequencies of events of genetic recombination occurring primarily within subpopulations of closely related strains. This study offers important insights into the population genetics and reproduction mode of L. panamensis, paving the way to better understand their population structure and the emergence and maintenance of key eco-epidemiological traits.
Assuntos
Leishmania braziliensis , Leishmania guyanensis , Leishmania , Variação Genética , Genômica , Leishmania guyanensis/genéticaRESUMO
With few exceptions, spontaneous crossing over does not normally occur in male Drosophila. Drosophila ananassae males show considerable amounts of crossing over. In wild males of D. ananassae from Asian (2008) and Brazilian populations (1986 and 2007) variable frequencies of meiotic crossing over, estimated from chiasmata counts, suggested the existence of factors controlling male crossing over in these populations. To corroborate for such prediction, we present data on spontaneous recombination in F1 males of D. ananassae heterozygous for chromosomes of the same Brazilian populations (1986) and marker chromosomes using three testers stocks. Mean recombination value was low, although high variability existed between individual frequencies. Recombination frequencies between lines in each tester stock were not significantly different, excepting when the 3ple-px and 3ple-cy testers were compared (p < 0.05). These two testers differ in respect to the regional distribution of crossovers. The occurrence of recombination in chromosomes 2 and 3 in F1 males tested with e(65) se; bri ru was not related, suggesting they are under independent genetic control. Our data are consistent with proposed genetic factors controlling male crossing over in the tester stocks and to the presence of enhancers and suppressors of male crossing over segregating in the Brazilian populations (1986).
Assuntos
Drosophila/genética , Animais , Brasil , Inversão Cromossômica , Cromossomos de Insetos , Troca Genética , Marcadores Genéticos , Genética Populacional , Heterozigoto , Masculino , Recombinação GenéticaRESUMO
Giardia duodenalis is divided into eight assemblages (named A to H). Isolates of assemblage A are divided into four sub-assemblages (AI, AII, AIII and AIV). While isolates of sub-assemblage AII are almost exclusively detected in human hosts, isolates of assemblage B are encountered in a multitude of animal hosts and humans. Here, we isolated single cysts of G. duodenalis from a human stool sample and found that one of them had overlaps of assemblage AII and B alleles and an unexpectedly high number of variants of the beta-giardin (Bg) and GLORF-C4 (OrfC4) alleles. In addition, one of the Bg alleles of that cyst had a fragment of sub-assemblage AII interspersed with fragments of assemblage B, thus indicating that this allele may be a recombinant between sequences A and B. Our results are unprecedented and put a check on the statement that different assemblages of G. duodenalis represent species with different host specificities.(AU)
A espécie Giardia duodenalis é dividida em oito grupos (nomeados de A a H). Isolados do grupo A são divididos em quatro subgrupos (AI, AII, AIII and AIV). Enquanto isolados do subgrupo AII são detectados quase exclusivamente em hospedeiros humanos, isolados do subgrupo B são encontrados em uma grande variedade de hospedeiros entre animais e humanos. Neste trabalho, foi constatado que, dentre diversos cistos individualizados de G. duodenalis provenientes de fezes de origem humana, um cisto continha os alelos AII e B e um número inesperado de variantes de alelos codificadores de beta giardina e GLORF-C4. Ainda, um dos alelos beta giardina desse cisto possuía fragmentos AII intercalando um fragmento B, indicando que esse alelo pode ser um recombinante entre alelos AII e B. Os resultados aqui apresentados são inéditos e colocam em dúvida o conceito atual de que os diferentes grupos de G. duodenalis representam espécies distintas com diferentes graus de especificidade por hospedeiros.(AU)
Assuntos
Giardíase/classificação , Giardíase/genética , Triagem de Portadores Genéticos , Recombinação Genética , MicromanipulaçãoRESUMO
Abstract Giardia duodenalis is divided into eight assemblages (named A to H). Isolates of assemblage A are divided into four sub-assemblages (AI, AII, AIII and AIV). While isolates of sub-assemblage AII are almost exclusively detected in human hosts, isolates of assemblage B are encountered in a multitude of animal hosts and humans. Here, we isolated single cysts of G. duodenalis from a human stool sample and found that one of them had overlaps of assemblage AII and B alleles and an unexpectedly high number of variants of the beta-giardin (Bg) and GLORF-C4 (OrfC4) alleles. In addition, one of the Bg alleles of that cyst had a fragment of sub-assemblage AII interspersed with fragments of assemblage B, thus indicating that this allele may be a recombinant between sequences A and B. Our results are unprecedented and put a check on the statement that different assemblages of G. duodenalis represent species with different host specificities.
Resumo A espécie Giardia duodenalis é dividida em oito grupos (nomeados de A a H). Isolados do grupo A são divididos em quatro subgrupos (AI, AII, AIII and AIV). Enquanto isolados do subgrupo AII são detectados quase exclusivamente em hospedeiros humanos, isolados do subgrupo B são encontrados em uma grande variedade de hospedeiros entre animais e humanos. Neste trabalho, foi constatado que, dentre diversos cistos individualizados de G. duodenalis provenientes de fezes de origem humana, um cisto continha os alelos AII e B e um número inesperado de variantes de alelos codificadores de beta giardina e GLORF-C4. Ainda, um dos alelos beta giardina desse cisto possuía fragmentos AII intercalando um fragmento B, indicando que esse alelo pode ser um recombinante entre alelos AII e B. Os resultados aqui apresentados são inéditos e colocam em dúvida o conceito atual de que os diferentes grupos de G. duodenalis representam espécies distintas com diferentes graus de especificidade por hospedeiros.
Assuntos
Animais , Proteínas de Protozoários/genética , Giardia lamblia/genética , Cistos/genética , Proteínas do Citoesqueleto/genética , Alelos , Triagem de Portadores Genéticos/veterinária , Giardia lamblia/classificação , GenótipoRESUMO
The aim of this study was to assess oval conidia production in mutants for the reductase nitrate gene in C. sublineolum and verify the possibility of using them as a tool to transfer the genetic material in this species. The mutants used in the present study lost the ability to form falcate conidia but all produced oval conidia. The number of nuclei by conidium was evaluated. Oval conidia were efficient in the heterokaryon formation and these heterokaryons in liquid culture medium they also produced oval conidia in abundance. Recombinants were obtained and the genetic exchanges were confirmed by the RAPD analyses.
O fungo Colletotrichum sublineolum agente causal da antracnose em sorgo mostra dimorfismo conidial, produzindo conídios falcados ou ovais dependendo das condições de cultivo. Conídios falcados têm sido usados para obter heterocários entre mutantes complementares. Muitas linhagens de C. sublineolum não produzem conídios falcados ou produzem em quantidades insuficientes para analises. O objetivo do presente estudo foi avaliar a produção de conídios ovais em mutantes para o gene da nitrato redutase e verificar a possibilidade de sua utilização como ferramentas na transferência de material genético nesta espécie. Os mutantes usados neste estudo perderam a capacidade de produzir conídios falcados, porém todos produziram conídios ovais. O número de núcleos por conídio foi determinado. Conídios ovais foram eficientes na formação de heterocários e os heterocários quando cultivados em meio líquido também produziram conídios ovais em abundância. Recombinantes foram obtidos e as trocas genéticas foram confirmadas pelas análises de RAPD.
RESUMO
O termo cútis tricolor descreve a presença de máculas cutâneas hiper e ipocrômicas, adjacentes e congênitas, e é manifestação de mosaicismo cutâneo explicada pelo mecanismo de twin spotting alélico. Esse fenômeno consiste em forma particular de recombinação somática, com perda da heterozigose, que ocorre durante a mitose no embrião em formação. Apresenta-se caso de paciente masculino, 16 anos, com máculas hiper e hipocrômicas adjacentes no tronco, presentes desde o nascimento, assintomáticas. Não se detectaram outras anomalias.
The term cutis tricolor describes the presence of congenital hyper and hypopigmented skin macules and is a manifestation of skin mosaicism, explained by the allelic twin spotting mechanism. This phenomenon consists of a peculiar type of somatic recombination, with loss of heterozygosity, which occurs during mitosis in the forming embryo. We present the case of a male patient, aged 16, with congenital asymptomatic adjacent hyper and hypopigmented macules on the trunk. No other anomalies could be detected.
RESUMO
Las pandemias de gripe se han caracterizado hasta ahora por la adaptación en humanos de un virus que contiene determinantes antigénicos derivados de cepas de virus propios de aves para los cuales no existe inmunidad en humanos. La ausencia de vacunas y de fármacos eficaces contra una posible epidemia provoca una gran expectativa en cuanto a la repercusión que una pandemia de tales magnitudes tendrá sobre la humanidad no sólo en el aspecto económico sino sobre la tasa de mortalidad tan elevada que podría producirse. Este artículo va dirigido al personal de salud, tanto profesionales como estudiantes, con el fin de informarlos y prevenirlos frente a una nueva pandemia de influenza.
The influenza pandemies are characterized by the adaptation in humans of viruses that only affect the avian population. This is because there is not immunity by humans in front of these new serotypes of influenza. The absence of vaccines and efficient drugs against a possible pandemy, provoke huge expectations according to the repercussion of this kind of pandemy in the humanity, not only in the economical aspect but in a possible mortality rate that could be produced. This article is aimed at the professional and students of the health area. Its objective is to inform and prevent them in the case they need to face a new pandemy of influenza.
Assuntos
Masculino , Feminino , Vírus da Influenza A , Vírus da Influenza A Subtipo H1N1 , Influenza Aviária , Infecções por Orthomyxoviridae , Transmissão de Doença Infecciosa , EpidemiologiaRESUMO
El proceso evolutivo de un ser vivo se acelera cuanto mayor sea su capacidad para producir variabilidad genética, bien por mutación, bien por recombinación.Sin embargo, cuanto mayor sea esta capacidad, mayor también será el riesgo de acumular mutaciones deletéreas. La variabilidad genética es, por tanto, un proceso altamente regulado, de tal manera que las bacterias tienden a mantener una baja tasa de mutación. En diferentes poblaciones bacterianas analizadas hay siempre un porcentaje variable de cepas con una tasa de mutación superior a la frecuencia modal del resto de la población. Existe una relación directa entre la proporción de cepas que mutan y el grado de estrés del ambiente. Así, en los procesos infecciosos crónicos, en los que el tratamiento antibiótico es constante durante períodos prolongados, se observan los mayores porcentajes de bacterias que mutan, cercano al 50 por ciento de la población. Esta selección positiva de bacterias que mutan es debida al enorme potencial que presentan para desarrollar resistencia antibiótica (100 veces superior a una bacteria normal). Esta capacidad ha sido explotada, en algunos centros de investigación, como un modelo natural de evolución acelerada para predecir la facilidad con la que determinadas variantes resistentes pueden aparecer, saber qué posiciones serán las más susceptibles a los cambios y cuál será el costo para la bacteria. El laboratorio de microbiología debe hacer un esfuerzo por detectar estas cepas mutadoras antes de que desarrollen mecanismos de resistencia e induzcan el fracaso terapéutico
The potential of producing genetic variability, eitherby mutation or by recombination, is the driving for-ce of evolution in a living organism. Geneticvariability is a quite regulated process in which bac-teria tend to maintain a low mutation rate. However,a variable proportion of bacteria with a highermutation rate than that of the modal is alwayspresent in any population. Moreover, a direct rela-tionship exists between the proportion of mutatorstrains and environmental stress. In chronicinfectious diseases, due to prolonged antibioticregimens, nearly 50% of the population may berepresented by mutating bacteria. Such a positiveselection is due to the capacity of this type of strainsto develop antibiotic resistance (100 fold higherthan normal bacteria) This trait has been used asan accelerated-evolution model to predict the easeof certain resistant variants to emerge as well asto infer which targets are more prone to bemodified and the concomitant cost that suchvariability would imply to the organism.The Microbiology laboratory might then doan effort to detect mutating strains before theappearance of resistance mechanisms that maylead to therapeutic failures.Keywords: evolution, genetic recombination,mutagenesis, bacterial drug resistance.Fecha de recepción