Fossil microbialites of the Ja?ba Formation, Bambu? Group, Minas Gerais, Brazil.

Microbialites are carbonatic deposits, whose genesis is organosedimentary, deposited by benthic microbial mats. Microbialites are the most common fossils in rocks of the Proterozoic, worldwide and in Brazil. They exhibit morphological diversity since the oldest Archean forms, and are fundamental in studies concerning the biota and environmental aspects of past times, allowing better comprehension of biological and carbonate biosedimentary evolution through time. Microbial laminites and thrombolites of the Ja?ba Formation, upper Bambu? Group, are described. Thrombolites show columnar and irregular shape, centimetric size, and are locally coalescent. Laminites, overlying the thrombolitic strata, display smooth, wavy, and crenulate synoptic relief. Five microfabrics and microfossils of two distinct morphologies, coccoidal and filamentous, were identified. Microfabrics may be of biogenic or abiogenic origin, representing different processes involved in the formation of microbialites. Thus, microbialites and microfossils of the Ja?ba Formation show potential to better understand the producer biota in the context of the Ediacaran-Cambrian transition, probable age of this unit, and an important moment of profound changes in biosphere, due to the diversification of metazoans.Os microbialitos s?o dep?sitos carbon?ticos cuja origem ? organossedimentar, depositados por esteiras microbianas bent?nicas. Microbialitos s?o os f?sseis mais comuns encontrados no Brasil e no mundo em rochas do Proterozoico. Apresentam diversidade morfol?gica desde as formas mais antigas, datadas do Arqueano, e s?o fundamentais nos estudos da paleobiota e aspectos ambientais pret?ritos, permitindo o melhor entendimento da evolu??o biol?gica e biossedimentar carbon?tica ao longo do tempo geol?gico. Neste trabalho s?o descritos laminitos e tromb?litos da Forma??o Ja?ba, na por??o superior do Grupo Bambu?. Os tromb?litos encontrados apresentam formas colunares e irregulares, centim?tricas e pontualmente coalescentes. J? os laminitos microbiais, sobrejacentes aos tromb?litos, apresentam lamina??es com relevo sin?ptico entre plano, ondulado e crenulado. Cinco microtexturas e microf?sseis de duas morfologias distintas, cocoides e filamentosos, foram identificados. As microtexturas s?o de origem biog?nica e abiog?nica, e representam os diferentes processos de forma??o dos microbialitos. Dessa forma, os microbialitos e microf?sseis encontrados na Forma??o Ja?ba apresentam potencial para melhor compreender a paleobiota produtora no contexto da transi??o Ediacarano?Cambriano, prov?vel idade desta unidade, um momento importante de mudan?as profundas na biosfera, devido ? diversifica??o dos metazo?rios

Low-dose of benznidazole promotes therapeutic cure in experimental chronic Chagas' disease with absence of parasitism in blood, heart and colon.

Studies suggest that the dose of the standard benznidazole (BNZ) treatment regimen might be too high. We investigated the efficacy of BNZ 20 and 40 mg/kg/day compared with standard dose (100 mg/kg/day) to induce cure in mice infected with Trypanosoma cruzi Y strain in the acute and chronic phases of Chagas' disease. Our findings indicate that an experimental treatment with a BNZ low-dose (40 mg/kg/day) is similarly effective as the usual dose in the chronic mice model (100% of cure). In addition, the treatment in the chronic model of Chagas' disease presented better results than the acute model and colon appears to be a key tissue when it comes to evaluating treatment efficacy compared to blood and heart. Therefore, our data suggest the reconsideration of the current therapy, mainly in the chronic phase of the disease

Immunogenicity and protective efficacy of a new Leishmania hypothetical protein applied as a DNA vaccine or in a recombinant form against Leishmania infantum infection.

Vaccination is one the most important strategies for the prevention of visceral leishmaniasis (VL). In the current study, a new Leishmania hypothetical protein, LiHyP, which was previously showed as antigenic in an immunoproteomic search in canine VL, was evaluated regarding its immunogenicity and protective efficacy against Leishmania infantum infection. The effects of the immunization using LiHyP were evaluated when administered as a DNA plasmid (DNA LiHyP) or recombinant protein (rLiHyP) associated with saponin. The immunity elicited by both vaccination regimens reduced the parasitism in liver, spleen, bone marrow and draining lymph nodes, being associated with high levels of IFN-?, IL-12, GM-CSF, and specific IgG2a antibody, besides low production of IL-4, IL-10, and protein and parasite-specific IgG1 antibodies. CD4+ T cells contributed more significantly to IFN-? production in the rLiHyP/saponin group, while CD8+ T cells were more important in the production of this cytokine in the DNA LiHyP group. In addition, increased IFN-? secretion, along with low levels of IL-10, were found when PBMCs from treated VL subject and healthy individuals were stimulated with the recombinant protein. In conclusion, when administered either as a DNA plasmid or recombinant protein, LiHyP can direct the immune response towards a Th1 immune profile, protecting animals against L. infantum infection; therefore, it can be seen as a promising immunogen against human VL