Phylogenetic analyses of the genera Pipra, Lepidothrix and Dixiphia (Pipridae, Passeriformes) using partial cytochrome b and 16S mtDNA genes

The piprids (manakins) are small-bodied Neotropical birds characterized by sexual dimorphism of the plumage and elaborate courtship rituals. The phylogenetic relationships of some of piprid genera, in particular Pipra , are not well defined. Recently, Pipra was divided into three distinct groups, and the recognition of two new genera — Lepidothrix and Dixiphia — was suggested, based on the characteristic of the syringial morphology. In the present study, we analyse the phylogenetic relationships among these genera on the basis of data from the mitochondrial genes rRNA 16S and cytochrome b . Bayesian Inference (BI), Maximum Parsimony (MP) and Maximum Likelihood (ML) methods of analyses produced phylogenetic trees with very similar topologies with regard to the groupings formed by the species representing the three genera. These results indicate that the genera Pipra, Lepidothrix and Dixiphia do not constitute a single monophyletic clade, and support the current hypothesis of polyphyletism for the former representatives of the genus Pipra . However, the topologies presented do not coincide exactly with the phylogeny suggested by the morphological data with regard to the relationship between these three groups and the remaining piprid genera analysed here, emphasizing the need for further studies of this group of birds. The agreement between the molecular data presented here and the biogeographical information available for some of the species analysed appears to confirm the potential of using segments of the mitochondrial genome for the study of phylogeographical patterns in this group of organisms.     

Molecular phylogeny of mangrove oysters (Crassostrea) from Brazil

As a result of phenotypic plasticity, the cupped oysters (Crassostrea)are difficult to identify by means of their morphology. However,molecular DNA markers are a useful means of discriminating amongthese species. Cupped oysters are one of the most widely culturedmarine invertebrates and correct species identification is importantin aquaculture. Moreover, the molecular phylogeny of the genusCrassostrea and the subfamily Crassostreinae is still not clear.In order to identify the Brazilian cupped oysters and to clarifythe phylogenetic relationships of these species, we sequenceda fragment of mitochondrial DNA (16S rRNA gene) from 120 specimenscollected at nine different sites distributed along the Braziliancoast. The results identified two native species of oyster:Crassostrea gasar, from the Amazon to the Parnaíba delta;and Crassostrea rhizophorae, from the northeast (Fortim) tothe south of Brazil. An exotic Crassostrea species, closelyrelated to Indo-Pacific Crassostrea, was found in one locationin the north of Brazil. Crassostrea showed monophyly and theAtlantic oysters are clearly separated from the Indo-Pacificcluster. (Received 30 May 2006; accepted 12 April 2007)     

Influence of Th1/Th2 Cytokines and Nitric Oxide in Murine Systemic Infection Induced by Sporothrix schenckii

In an attempt to elucidate the effects of Sporothrix schenckii infection on the immune response, our laboratory has developed a murine model of disseminated sporotrichosis. Helper T cells can be further subdivided into Th1 and Th2 phenotypes. The differentiation of two subsets of T lymphocytes is driven by IL-12 and IL-4 cytokines, respectively. Th1 cells produce IFN-γ that activate macrophages and promote cell-mediated immunity. In addition, we found low levels of iNOS and NO production in the initial (1st and 2nd weeks) and final (9th and 10th weeks) periods of the infection, in contrast with the period of week 4 to 7 of elevated values. The determination of IFN-γ and IL-12 are in agreement with NO/iNOS detection, showing the presence of cellular immune response throughout the infectious process. However, the production of IL-4 shows an increase in levels after the 5th and 6th weeks suggesting a participation of Th2 response in this period as well. Regarding these results, the study demonstrated that in experimental sporotrichosis infection the cellular immune response participated throughout the period analyzed as a nitric oxide dependent mechanism. In contrast, the presence of Th2 response began in the 5th week, suggesting the participation of humoral immune response in advanced stages of sporotrichosis.