Helicobacter pylori CagA elicits BRCAness to induce genome instability that may underlie bacterial gastric carcinogenesis

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Improving enzyme characteristics by gene shuffling; application to β-glucosidase

The genes of family 3 β-glucosidase enzymes consist of five distinct regions; the N-terminal residues, an N-terminal catalytic domain, a nonhomologous region, a C-terminal domain of unknown function and the C-terminal residues. The β-glucosidase genes derived from Cellvibrio gilvus (CG) and Agrobacterium tumefaciens (AT) have been subjected to gene deletion, truncation and shuffling. The folding information was found to be distributed unevenly across the different regions based on the gene manipulation results. Chimeric enzymes with improved enzyme characteristics were obtained only by gene shuffling at the C-terminal domain.     

Effects of benzene in a micronucleus test on peripheral blood utilizing acridine orange-coated slides.

A micronucleus test was conducted on the peripheral blood of mice and rats utilizing acridine orange-coated slides (AO-coated method) after oral administration of benzene. Blood was sampled at 0, 24, 48, and 72 h after administration of benzene at doses of 500, 1000, and 2000 mg/kg in both mice and rats. The highest occurrence of micronucleated reticulocytes (MNRETs) was observed at 48 h after administration in both species. Species differences was found in the frequency of MNRETs, with the number being lower in rats than in mice. The present results indicate that the micronucleus test can easily detect chromosome aberrations in peripheral blood induced by benzene administration in both mice and rats. Furthermore, the AO-coated method used in this study was simpler to perform and allowed for easier detection of the effect than the conventional method.     

nalB-type mutations causing the overexpression of the MexAB-OprM efflux pump are located in the mexR gene of the Pseudomonas aeruginosa chromosome

Hemolysin of Aeromonas sobria possesses both cytotoxic activity against mammalian cells and enterotoxic activity. Histopathological examination revealed that hemolysin causes diarrhea without damaging the intestinal epithelial cells. And the fluid accumulated in the mouse intestinal loop by the action of the hemolysin is watery. These observations indicated that the enterotoxic activity of hemolysin is not dependent on its cytotoxic activity. To clarify the mechanism of the enterotoxic action of hemolysin, we examined cyclic nucleotide levels in cultured cells exposed to this toxin. These results showed that hemolysin stimulates the production of cyclic AMP in cultured cells and the cyclic AMPs thus produced emerge in the milieu of cells.     

Modification of the porin function by the membrane components used for the reconstitution of model membranes

Diffusion rate of the cationic solute through the porin pore was five times higher in the vesicles made of acidic phospholipids than in that of zwitterionic phospholipids. In contrast, diffusion of the anionic solute through these vesicles was reciprocally reversed. Diffusion ofpara-nitrophenyl phosphate was enhanced in the presence of lipopolysaccharide and the phospholipids extracted from bacterial cells as compared with the diffusion through porin in phosphatidyl choline.     

S-phase accumulation of human salivary adenocarcinoma cells by cycloheximide

Cycloheximide (1.0 ug/ml) reversibly induced a 1.7-fold increase in the distribution of cells in S phase and a 0.9-fold decrease in G1 phase in DNA histograms of human salivary adenocarcinoma cells (HSG). At this time, cycloheximide inhibited the synthesis of proteins by HSG cells and secretion of proteins in the media to 28.1% and 9% of the control values, respectively, which resulted in the almost complete arrest of cell reproduction. This indicates that HSG cells can pass through G1 to S phase even under the conditions of the arrest of protein synthesis.