Compartmentalization and regulation of arylsulfatase activities in Streptomyces sp., Microbacterium sp. and Rhodococcus sp. soil isolates in response to inorganic sulfate limitation

Arylsulfatases allow microorganisms to satisfy their sulfur (S) requirements as inorganic sulfate after sulfate ester hydrolysis. Our objectives were to investigate the arylsulfatase activities among soil isolates, especially Streptomyces sp., Microbacterium sp. and Rhodococcus sp., because such investigations are limited for these bacteria, which often live in sulfate-limited conditions. Physiological and biochemical analyses indicated that these isolates possessed strong specific arylsulfatase activities ranging from 6 to 8 U. Moreover, for Streptomyces sp., an arylsulfatase localization study revealed 2 forms of arylsulfatases. A first form was located in the membrane, and a second form was located in the intracellular compartment. Both arylsulfatases had different patterns of induction. Indeed, the intracellular arylsulfatase was strictly induced by inorganic sulfate limitation, whereas the membrane arylsulfatase was induced both by substrate presence or S demand independently. For Microbacterium and Rhodococcus isolates, only a membrane arylsulfatase was found. Consequently, our results suggest the presence of a previously undescribed arylsulfatase in these microorganisms that allows them to develop an alternative strategy to fulfill their S requirements compared to bacteria previously studied in the literature.     

Varicella Coinfection in Patients with Active Monkeypox in the Democratic Republic of the Congo

From 2006 to 2007, an active surveillance program for human monkeypox (MPX) in the Democratic Republic of the Congo identified 151 cases of coinfection with monkeypox virus and varicella zoster virus from 1158 suspected cases of human MPX (13%). Using clinical and socio-demographic data collected with standardized instruments by trained, local nurse supervisors, we examined a variety of hypotheses to explain the unexpectedly high proportion of coinfections among the sample, including the hypothesis that the two viruses occur independently. The probabilities of disease incidence and selection necessary to yield the observed sample proportion of coinfections under an assumption of independence are plausible given what is known and assumed about human MPX incidence. Cases of human MPX are expected to be underreported, and more coinfections are expected with improved surveillance.     

Generation of high specificity of effect through low-specificity binding of proteins to DNA

It is proposed that proteins can bind with relatively low-affinity and specificity to multiple sites, defined as sequence motifs, on polynucleotide chains, and that such binding can collectively be turned into high-affinity, high-specificity binding through cooperative effects, especially when the sequence motifs recur periodically. The selection of individual nucleotides has in general been thought to be the condition of the existence and conservation of function in most of the noncoding sequences. This condition seems unnecessary. Calculations are presented as a step in the direction of giving credibility to a model of stable gene repression.     

Initiation and outcomes with Class Ic antiarrhythmic drug therapy

Background

Expert opinion recommends performing exercise testing with initiation of Class Ic antiarrhythmic medication.

Characterization of Porin from Roseobacter denitrificans

Porin from Roseobacter denitrificans was isolated and purified to homogeneity. The pore characteristics from this marine bacterium were compared to those of its phylogenetically closely related freshwater bacteria Rhodobacter capsulatus 37b4, Rhodobacter sphaeroides and Rhodopseudomonas blastica. The porin formed weakly cation-selective, general diffusion pores in lipid bilayer membranes. High transmembrane potentials caused channel closing in steps that were of one or two thirds of the initial on-steps indicating that the porin of R. denitrificans comprised three more or less independent channels similar to PhoE and OmpC of Escherichia coli and the porin of Rhodobacter capsulatus. Prediction of the secondary structure of the 36 N-terminal amino acid residues indicated two transmembrane -strands similar to those of the porins of Rhodobacter capsulatus 37b4 and Rhodopseudomonas blastica. Differences of the single channel conductivities between the porin of R. denitrificans and those of the related freshwater bacteria show that R. denitrificans evolved porin channels that are well adapted to the marine habitat.     

Cloning of a full-length symbiotic hemoglobin cDNA and in situ localization of the corresponding mRNA in Casuarina glauca root nodule

We have characterized a full-length cDNA ( hb -Cg1F) that represents symbiotic mRNA hemoglobin ( hb ) from Casuarina glauca root nodules. In situ hybridization was used to examine the correlation between hb -Cg1F mRNA and the state of the Frankia infection process. The efficiency of in situ hybridization using DIG-labeled vs [³⁵S]-labeled probes was compared. The expression of hb -Cg1F gene is induced in young infected host cells prior to the detection of Frankia nif H mRNA. Since Frankia does not form vesicles in C. glauca nodules, it is proposed that Hb is necessary to reduce the O₂ concentration in the cytoplasm of the host cells before the nif genes are expressed.