Comparison of antimicrobial resistant Escherichia coli in wild and captive Japanese serows.

The fecal Escherichia coli isolated from wild Japanese serows living in mountainous areas away from humans and those from captive serows kept in human areas were examined for antimicrobial resistance and the possession of transferable R plasmids. Of 874 E. coli strains isolated from 283 wild serows in 1980-1981, only 11 (1.3%) were resistant to at least one of 6 antimicrobial drugs; ampicillin, streptomycin, tetracycline, chloramphenicol, kanamycin and sulfadimethoxin. Seven (2.5%) individuals were found to carry resistant E. coli. To heighten the isolation frequency of drug-resistant strains, fecal samples of 244 wild serows in 1983-1984 were cultured directly onto drug-supplemented media. Only 12 (4.9%) serows were shown to have drug-resistant E. coli. No transferable R plasmid was detected among a total of 87 resistant strains from wild serows. In contrast, all 33 captive serows except one which was kept only one day after capture, showed resistant E. coli and 20 (60.6%) serows were excreting R plasmid-carrying E. coli. Of 161 drug-resistant strains from captive serows, 50 (31.1%) were found to carry R plasmids. Wild serows seemed to readily change to harbor resistant E. coli almost as soon they were reared in human areas without direct exposure to drugs. These results lead to the conclusion that drug-resistant E. coli can probably be used as microbial indicator for natural environmental pollution.     

Occurrence and molecular characterization of strobilurin resistance in cucumber powdery mildew and downy mildew

ABSTRACT Between 1998 and 1999, control failure of powdery mildew (Podosphaera fusca) and downy mildew (Pseudoperonospora cubensis) by the strobilurin fungicides azoxystrobin and kresoxim-methyl was observed in cucumber-growing areas of Japan. Results from inoculation tests carried out on intact cucumber plants and leaf disks clearly showed the distribution of pathogen isolates highly resistant to azoxystrobin and kresoximmethyl. Fragments of the fungicide-targeted mitochondrial cytochrome b gene were polymerase chain reaction amplified from total pathogen DNA and their sequences analyzed to elucidate the molecular mechanism of resistance. A single point mutation (GGT to GCT) in the cytochrome b gene, resulting in substitution of glycine by alanine at position 143, was found in resistant isolates of downy mildew. This substitution in cytochrome b seemed to result in high resistance to strobilurins in this pathogen. The same mutation was found in some but not all resistant isolates of powdery mildew. This study suggests that a mutation at position 143 in the target-encoding gene, resulting in an amino acid substitution, was probably a major cause of the rapid development of high strobilurin resistance in these two pathogens.     

Background Data on Developmental Parameters During the Gestation Period in Rats

Abstract: Background data during the gestation period were obtained from 128 Wistar Hannover GALAS rats and 26 Crl:CD(SD) pregnant rats in the control groups of our previous toxicity studies. The body weights of dams in the Wistar Hannover GALAS rats were significantly lower throughout the gestation period than those in the Crl:CD(SD) rats. In contrast, the time-dependent change in the body weight gain (%) of dams showed very similar trends in both strains. The mean number of live embryos/fetuses in the Wistar Hannover GALAS rats was 12.0, and was lower than that (14.5) in the Crl:CD(SD) rats. The placental weights gradually increased with pregnancy progression and reached a plateau on gestation day (GD) 19, although the embryo/fetal weights rapidly increased from GD 17 to GD 21. The embryo/fetal weights in the Wistar Hannover GALAS rats were significantly lower on only GD 21 than those in the Crl:CD(SD) rats. It is considered that this fetal weight difference between the strains develops during the fetal period, but not during the organogenesis period. In contrast, there were no differences in the placental weights between the two strains. Microscopically, the thickness of the labyrinth zone in the Wistar Hannover GALAS rats was thicker throughout the gestation period than that in the Crl:CD(SD) rats.     

Role of adaptor TRIF in the MyD88-independent toll-like receptor signaling pathway

Stimulation of Toll-like receptors (TLRs) triggers activation of a common MyD88-dependent signaling pathway as well as a MyD88-independent pathway that is unique to TLR3 and TLR4 signaling pathways leading to interferon (IFN)-beta production. Here we disrupted the gene encoding a Toll/IL-1 receptor (TIR) domain-containing adaptor, TRIF. TRIF-deficient mice were defective in both TLR3- and TLR4-mediated expression of IFN-beta and activation of IRF-3. Furthermore, inflammatory cytokine production in response to the TLR4 ligand, but not to other TLR ligands, was severely impaired in TRIF-deficient macrophages. Mice deficient in both MyD88 and TRIF showed complete loss of nuclear factor kappa B activation in response to TLR4 stimulation. These findings demonstrate that TRIF is essential for TLR3- and TLR4-mediated signaling pathways facilitating mammalian antiviral host defense.     

Baddeleyite-Type High-Pressure Phase of TiO2

A high-pressure phase of TiO(2), which had been observed by shock-wave experiments and remained unresolved, has been studied by in situ x-ray diffraction. The single phase was formed at 20 gigapascals and 770 degrees C with the use of sintered-diamond multianvils; it has the same structure as baddeleyite, the stable phase of ZrO(2) at ambient conditions. The coordination number of Ti increases from six to seven across the rutile to baddeleyite transition, and the volume is reduced by approximately 9 percent.