Microbial diversity of soils on the banks of the Solimões and Negro rivers, state of Amazonas, Brazil.

Analysis of bacterial diversity in soils along the banks of the Solimões and Negro rivers, state of Amazonas, Brazil, was by partial sequencing of the genes codifying the rDNA16S region. Diversity of operational taxonomic units (OTU) and of the divergent sequences obtained were applied in comparative analysis of microbiological diversity in the two environments, based on richness estimators and OTU diversity indices. The higher OTU diversity in the Solimões was based on the higher number of parameters that evoke this.

Acute effects of chemically dispersed crude oil on gill ion regulation, plasma ion levels and haematological parameters in tambaqui (Colossoma macropomum).

The main goal of this study was to investigate the toxicological effects of the chemical dispersant Corexit 9500, crude oil and the combination of the two components in the form of chemically dispersed crude oil (CO+DIS) on the ion regulation of the tropical fish tambaqui (Colossoma macropomum). Gill ion regulation was evaluated on the basis of unidirectional flux measurements (influx-J(in), efflux-J(out) and net flux-J(net)) of Na(+), Cl(-) and K(+). Plasma ion composition, haematocrit, haemoglobin and glucose concentrations in the blood of tambaqui were determined by classical methods.

One-step purification of metallothionein extracted from two different sources.

We describe a one-step purification of hepatic metallothionein from the Amazon fish Colossoma macropomum injected with cadmium and from the copper-loaded metallothionein from the yeast Saccharomyces cerevisiae, performed by affinity chromatography through metal-chelating columns. Yeast metallothionein was purified from Cu2+-loaded resin and eluted by a continuous EDTA gradient whereas hepatic metallothionein extracted from fishes was purified by Ni2+-loaded resin and eluted by a continuous imidazol gradient. Purified metallothioneins were evaluated by SDS-PAGE and characterized by UV spectra of the apo- and Cd2+-loaded protein.