Two modes of evolution shape bacterial strain diversity in the mammalian gut for thousands of generations

How and at what pace bacteria evolve when colonizing healthy hosts remains unclear. Here, by monitoring evolution for more than six thousand generations in the mouse gut, we show that the successful colonization of an invader Escherichia coli depends on the diversity of the existing microbiota and the presence of a closely related strain. Following colonization, two modes of evolution were observed: one in which diversifying selection leads to long-term coexistence of ecotypes and a second in which directional selection propels selective sweeps. These modes can be quantitatively distinguished by the statistics of mutation trajectories. In our experiments, diversifying selection was marked by the emergence of metabolic mutations, and directional selection by acquisition of prophages, which bring their own benefits and costs. In both modes, we observed parallel evolution, with mutation accumulation rates comparable to those typically observed in vitro on similar time scales. Our results show how rapid ecotype formation and phage domestication can be in the mammalian gut.info:eu-repo/semantics/publishedVersio

Complex basis of hybrid female sterility and Haldane's rule in Heliconius butterflies: Z-linkage and epistasis

Hybrids between species are often sterile or inviable. Hybrid unfitness usually evolves first in the heterogametic sex—a pattern known as Haldane's rule. The genetics of Haldane's rule have been extensively studied in species where the male is the heterogametic (XX/XY) sex, but its basis in taxa where the female is heterogametic (ZW/ZZ), such as Lepidoptera and birds, is largely unknown. Here, we analyse a new case of female hybrid sterility between geographic subspecies of Heliconius pardalinus. The two subspecies mate freely in captivity, but female F1 hybrids in both directions of cross are sterile. Sterility is due to arrested development of oocytes after they become differentiated from nurse cells, but before yolk deposition. We backcrossed fertile male F1 hybrids to parental females and mapped quantitative trait loci (QTLs) for female sterility. We also identified genes differentially expressed in the ovary as a function of oocyte development. The Z chromosome has a major effect, similar to the ‘large X effect’ in Drosophila, with strong epistatic interactions between loci at either end of the Z chromosome, and between the Z chromosome and autosomal loci on chromosomes 8 and 20. By intersecting the list of genes within these QTLs with those differentially expressed in sterile and fertile hybrids, we identified three candidate genes with relevant phenotypes. This study is the first to characterize hybrid sterility using genome mapping in the Lepidoptera and shows that it is produced by multiple complex epistatic interactions often involving the sex chromosome, as predicted by the dominance theory of Haldane's rule

Crescimento micelial in vitro de treze isolados de Corynespora cassiicola submetidos a diferentes temperaturas.

Corynespora cassiicola (Berk. & Curt.), fungo que causa a doença conhecida como mancha-alvo na cultura da soja ocorre em todo o Brasil. Considerando que os isolados de C. cassiicola apresentam variações nas características morfológicas, comportando-se de maneira distinta quanto ao crescimento micelial, o estudo do desenvolvimento deste fungo faz-se necessário para facilitar a multiplicação de inóculo em laboratório. Por este motivo, o objetivo foi avaliar o crescimento micelial in vitro de 13 isolados de C. cassiicola submetidos a diferentes temperaturas. Isolados da micoteca da Embrapa soja (307, 310, 311, 312, 313, 317, 318, 322, 605, 629, 646, 649 e 651) foram repicados em placas de Petri contendo BDA e incubados nas temperaturas de 18, 21, 24, 27 e 30 ± 2ºC, sendo a avaliação do crescimento micelial realizada por medições diárias do diâmetro das colônias. O delineamento experimental foi inteiramente casualizado em arranjo fatorial 13 x 5 (isolados x temperaturas) totalizando 65 tratamentos com cinco repetições. Com os dados obtidos calculou-se o índice de velocidade de crescimento micelial (IVCM) que foram submetidos à análise de variância, sendo as médias comparadas por meio do teste de Scott-Knott, ao nível de 5% de probabilidade. Verificou-se diferença estatística entre o crescimento micelial dos isolados, entre as temperaturas e também na interação isolado x temperatura. A maioria dos isolados apresentou maior IVCM quando incubados em temperaturas superiores a 24ºC, com exceção do isolado 307 que atingiu maior IVCM em temperaturas inferiores a 24ºC. Destaque foi dado ao isolado 307 que obteve o menor IVCM médio, enquanto que os isolados 318 e 646 apresentaram maior IVCM médio (p<0,05). Assim, concluiu-se que houve variabilidade entre os isolados de C. cassiicola para o IVCM em relação à temperatura, devendo ser observado a faixa ótima de crescimento para cada isolado

A brain-sparing diphtheria toxin for chemical genetic ablation of peripheral cell lineages.

Conditional expression of diphtheria toxin receptor (DTR) is widely used for tissue-specific ablation of cells. However, diphtheria toxin (DT) crosses the blood-brain barrier, which limits its utility for ablating peripheral cells using Cre drivers that are also expressed in the central nervous system (CNS). Here we report the development of a brain-sparing DT, termed BRAINSPAReDT, for tissue-specific genetic ablation of cells outside the CNS. We prevent blood-brain barrier passage of DT through PEGylation, which polarizes the molecule and increases its size. We validate BRAINSPAReDT with regional genetic sympathectomy: BRAINSPAReDT ablates peripheral but not central catecholaminergic neurons, thus avoiding the Parkinson-like phenotype associated with full dopaminergic depletion. Regional sympathectomy compromises adipose tissue thermogenesis, and renders mice susceptible to obesity. We provide a proof of principle that BRAINSPAReDT can be used for Cre/DTR tissue-specific ablation outside the brain using CNS drivers, while consolidating the link between adiposity and the sympathetic nervous system

Mediterranean spotted fever and encephalitis: a case report and review of the literature

Mediterranean spotted fever (MSF) is a disease caused by Rickettsia conorii and transmitted by the brown dog tick Rhipicephalus sanguineus. It is widely distributed through southern Europe, Africa, and the Middle East. It is an emerging or a reemerging disease in some regions. Countries of the Mediterranean basin, such as Portugal, have noticed an increased incidence of MSF over the past 10 years. It was believed that MSF was a benign disease associated with a mortality rate of 1-3% before the antimicrobial drug era. It was called benign summer typhus. Severe forms were described in 1981, and the mortality rate reached 32% in Portugal in 1997. However, neurological manifestations associated with brain lesions are a rare event. We describe the case of a man with fever, maculopapular rash, a black spot, and hemisensory loss including the face on the left side of the body with brain lesions in the imaging studies

Intestinal protozoa parasites association with anemia in people from Brazilian western Amazon communities

Introduction: Nowadays intestinal parasitic infection remains an important public health trouble in Latin and South America, emphasizing the Amazon region. Furthermore, intestinal parasites have been considered important factors in etiology of nutritional anemia and malnutrition. Objective: This study aimed to evaluate the intestinal parasitic infection and its possible association with anemia in people from Amazon communities. Methods: The study was a research in documentary records, descriptive, retrospective and cross-sectional, with confirmed cases of parasites infection found in State Hospital of Cacoal-Rondônia, Brazilian Western Amazon. The parameters evaluated were gender, age, race, parasites, hematocrit and hemoglobin. Results: Females where slight higher for the number of cases of parasites occurrence (51%) compared to males (49%) and children had higher parasitic index (43%) followed by adults (37%), teenagers (11%) and seniors (9%). With regards to race, pardos (brown skin color) group was the most affected by the parasites with 69% of cases, followed by caucasians (17%), indians (11%) and blacks (3%). The major parasites diagnosed were Endolimax nana (55%), Giardia lamblia (28%), Entamoeba coli (14%) and Iodamoeba bütschlii (3%). In relation to the association of intestinal parasites and anemia, children had a 60% anemia increase when compared to adults (p &lt;0.05) and the indians increased by 100% anemia when paired against caucasians (p &lt;0.05).Conclusion: Thus, it is suggested that attention should be given to the increase in protozoa parasitic infection prevalence in Amazonian communities and expedite the emergency of improvements in political and sanitation programs of water treatment and waste and sewer management

Relatório de gestão 2001-2004.

Embrapa Informática Agropecuária. Pesquisa e Desenvolvimento. Ações gerenciais estratégicas. Transferência de tecnologia e comunicação empresarial. Gestão Institucional. Prêmios recebidos. Infra-estrutura física. Gestão de Recursos Financeiros. Gestão de Recursos Humanos.bitstream/CNPTIA/10727/1/doc51.pdfAcesso em: 29 maio 2008