Microbial diversity was evaluated in an anoxic zone of Tucuruí Hydroelectric Power Station reservoir in Brazilian Amazonia using a culture-independent approach by amplifying and sequencing fragments of the 16S rRNA gene using metagenomic DNA as a template. Samples obtained from the photic, aphotic (40 m) and sediment (60 m) layers were used to construct six 16S rDNA libraries containing a total of 1,152 clones. The sediment, aphotic and photic layers presented 64, 33 and 35 unique archaeal operational taxonomic units (OTUs). The estimated richness of these layers was evaluated to be 153, 106 and 79 archaeal OTUs, respectively, using the abundance-based coverage estimator (ACE) and 114, 83 and 77 OTUs using the Chao1 estimator. For bacterial sequences, 114, 69 and 57 OTUs were found in the sediment, aphotic and photic layers, which presented estimated richnesses of 1,414, 522 and 197 OTUs (ACE) and 1,059, 1,014 and 148 OTUs (Chao1), respectively. Phylogenetic analyses of the sequences obtained revealed a high richness of microorganisms which participate in the carbon cycle, namely, methanogenic archaea and methanotrophic proteobacteria. Most sequences obtained belong to non-culturable prokaryotes. The present study offers the first glimpse of the huge microbial diversity of an anoxic area of a man-made lacustrine environment in the tropics.

As constantes de dissociação aparentes (pK a ) de quatro 2-hidroxinaftoquinonas, diferentemente substituídas em C-3, foram determinadas em meio aquoso-etanólico (1:1, v/v), utilizando titulações pH-métricas e espectrofotométricas. O isolapachol (pK a <6) mostrou ser mais ácido que seu análogo natural, o lapachol, (pK a >6). Os derivados 3-metilaminados apresentam dois valores de pK a , um relacionado ao grupo enólico e o outro ao sal de amônio, e são zwitteriônicos, em larga extensão, em pH fisiológico. As possíveis conseqüências desses parâmetros frente a suas atividades biológicas são discutidas.The apparent dissociation constants (pK a ) of four 2-hydroxynaphthoquinones, differently substituted at C-3, were determined in water:ethanol (1:1, v/v) solutions by pH-metric and hybrid pH-metric/UV titration methods. Isolapachol (pK a < 6) was more acidic than lapachol (pK a > 6). Two pK a values were determined for each of the methylamino-derivatives investigated, the first relating to the enol function and the second to the ammonium salt. It was determined that under physiological pH, these derivatives would be to a large extension, zwitterionic. The possible effects of the measured parameters on the biological activities of the studied compounds are discussed.

To perform the a culture-independent characterization of the microbial diversity observed within a water body in the Amazon, we constructed a library of bacterial and archaeal 16S rRNA genes isolated from environmental samples from the Tucuruí Hydroelectric Plant reservoir. The sampling locations included the upstream compartment (MR), which is located 50 km upstream of the dam, and Itupiranga (ITU), which is located upstream on the Tocantins River at the inlet of the reservoir. The bacterial phyla Cyanobacteria (46%), Proteobacteria (12%), Actinobacteria (9%), Bacteroidetes (4%) and Verrucomicrobia (2%) were identified at the MR. Phyla including the Chloroflexi, Acidobacteria, Planctomycetes and TM6 candidate division were observed at a frequency of <2%. The phyla Cyanobacteria (62%), Proteobacteria (5%) and Actinobacteria (7%) were identified at ITU. The archaeal diversity was limited to the Euryarchaeota and Crenarchaeota phyla; the latter was found in greater abundance and mainly consisted of uncultured phylotypes. In both regions, 25% and 95% of the bacteria and archaea, respectively, that were identified were previously unclassified. The phylum Cyanobacteria was almost exclusively represented by the genus Synechococcus sp.; however, a wide variety of microorganisms from the phylum Proteobacteria were identified from the classes alpha, gamma, delta and beta proteobacteria, with the latter being the most abundant. This study demonstrates that high prokaryotic diversity exists in the Amazonian rivers in addition to the previously reported megadiversity of fauna and flora.

medians followed the order Zn > Fe > Mn > Cu > Cr > Cd in MMELC and Zn > Cu > Fe > Mn > Cr > Cd in Meirim River. It is concluded that the Crassostrea rhizophorae oysters from the studied environments presented concentrations of all the metals proposed in the research and demonstrates its accumulating and bioindicator character.

This study aimed to describe the use of medicinal plants for the relief and treatment of pediatrics pathologies performed by parents of children registered in a Basic Health Unit. This is a cross-sectional, observational and analytical study that occurred from March until May 2016, with the participation of 176 individuals, using a semi-structured questionnaire as a research instrument. Descriptive statistics were applied for data analysis, using frequency distribution and chi-square test. Among all 177 indications of medicinal use of plants in childhood, considering the plant part and administration method, 61.6% converged with scientific data, 21.5% differed and 16.9% were new indications without a similar record in the literature. These results support the popular use of medicinal plants and show to need for greater awareness about the rational use of phytotherapy and stimulate scientific research, as they bring new elements about the therapeutic potential of different species.