High yield enzymatic conversion of intravascular leukotriene A4 in blood-free perfused lungs

Experiments to investigate the fate of intravascularly administered leukotriene (LT) A4, an unstable intermediate of LT generation, were performed in isolated, ventilated, and blood-free perfused rabbit lungs. LT extracted from the lung effluent were separated by different reverse phase and straight phase HPLC procedures as methylated and nonmethylated compounds. Identity of eluting LT was confirmed by UV spectrum analysis and immunoreactivity. Pulmonary artery injection of 75 to 300 nmol of LTA4 resulted in the rapid appearance of cysteinyl-LT as well as LTB4 in the recirculating perfusate. The yield of these enzymatically generated LTA4 metabolites vs non-enzymatic hydrolysis products (6-trans-LTB4, 5-trans-epi-LTB4, 5,6-dihydroxyeicosatetraenoic acids) ranged above 90%. Experiments with application of tritiated LTA4 showed exclusive origin of the detected LT from the exogenously applied precursor. The time course of cysteinyl-LT appearance in the perfusate suggested metabolism of LTC4 via LTD4 to LTE4, whereas there was no evidence for LTB4 omega-oxidation. In the dose range of LTA4 used, the enzymatic conversion of this LT precursor did not approach saturation. Collectively, these data indicate that the intact pulmonary vasculature contains a hitherto not described capacity for enzymatic conversion of intravascularly offered LTA4 to both cysteinyl-LT and LTB4. This may be of biological significance for a putative transcellular biosynthesis of LT in the pulmonary microcirculation upon contact with LTA4 feeder cells, such as activated granulocytes.     

Closed circular viral DNA and asymmetrical heterogeneous forms in livers from animals infected with ground squirrel hepatitis virus

To identify possible intermediates in the replication of ground squirrel hepatitis virus, we characterized the major forms of intracellular virus-specific DNA in the livers of infected ground squirrels. A variety of DNA species were found: covalently closed circular molecules, relaxed circular molecules, and a heterogeneous collection of molecules that migrated ahead of closed circular DNA during agarose gel electrophoresis. The heterogeneous DNA was at least partly single stranded, consisted of minus strands in a greater than eight-fold mass excess of plus strands, and was tightly associated with protein.     

Effect of acid and salt concentration in fresh-pack pickles on the growth of Clostridium botulinum spores.

The addition of various amounts of acetic acid to pureed cucumbers inoculated with Clostridium botulinum spores has shown that outgrowth is inhibited at pH 4.8 but not at pH 5.0. Inoculation experiments with whole cucumbers showed that as little as 0.9% acetic acid in the brine was sufficient to prevent outgrowth from spore inocula as high as 10(6)/cucumber. It was further shown that the rapid rate of acetic acid penetration into fresh-pack pickles prevents the growth of any C. botulinum spores that may be present.     

Phosphate starvation affects the synthesis of outer membrane proteins in Thiobacillus ferrooxidans

The outer membrane protein (omp40) component from the chemolithoautotrophic acidophilic Thiobacillus ferrooxidans is apparently regulated by the external pH and the concentration of phosphorus. Its amino-terminal sequence showed little identity with the Escherichia coli OmpC, OmpF or PhoE porins, but was 38.5% identical to the outer membrane channel-forming protein NosA from Pseudomonas stutzeri, whose expression is also regulated environmentally. In addition, the partial amino acid sequence of T. ferrooxidans omp40 showed between 34 and 38% identity with the amino-terminal end of the small outer membrane proteins Rck and PagC from Salmonella typhimurium and OmpX from Enterobacter cloacae.     

A Genome-wide RNAi Screen Reveals a Trio-Regulated Rho GTPase Circuitry Transducing Mitogenic Signals Initiated by G Protein-Coupled Receptors

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Highlights? Human cancers harbor frequent mutations in Gq-linked GPCRs and Gα_q subunits ? A genome-wide RNAi screen revealed that Trio is essential for activating AP-1 via Gα_q ? A network of Trio-regulated Rho GTPases and MAPKs links Gq to the nucleus ? A hard-wired Gq-Trio signaling axis promotes the growth of many human malignancies