Unraveling Antimicrobial Resistance Genes and Phenotype Patterns among Enterococcus faecalis Isolated from Retail Chicken Products in Japan

Multidrug-resistant enterococci are considered crucial drivers for the dissemination of antimicrobial resistance determinants within and beyond a genus. These organisms may pass numerous resistance determinants to other harmful pathogens, whose multiple resistances would cause adverse consequences. Therefore, an understanding of the coexistence epidemiology of resistance genes is critical, but such information remains limited. In this study, our first objective was to determine the prevalence of principal resistance phenotypes and genes among Enterococcus faecalis isolated from retail chicken domestic products collected throughout Japan. Subsequent analysis of these data by using an additive Bayesian network (ABN) model revealed the co-appearance patterns of resistance genes and identified the associations between resistance genes and phenotypes. The common phenotypes observed among E. faecalis isolated from the domestic products were the resistances to oxytetracycline (58.4%), dihydrostreptomycin (50.4%), and erythromycin (37.2%), and the gene tet(L) was detected in 46.0% of the isolates. The ABN model identified statistically significant associations between tet(L) and erm(B), tet(L) and ant(6)-Ia, ant(6)-Ia and aph(3’)-IIIa, and aph(3’)-IIIa and erm(B), which indicated that a multiple-resistance profile of tetracycline, erythromycin, streptomycin, and kanamycin is systematic rather than random. Conversely, the presence of tet(O) was only negatively associated with that of erm(B) and tet(M), which suggested that in the presence of tet(O), the aforementioned multiple resistance is unlikely to be observed. Such heterogeneity in linkages among genes that confer the same phenotypic resistance highlights the importance of incorporating genetic information when investigating the risk factors for the spread of resistance. The epidemiological factors that underlie the persistence of systematic multiple-resistance patterns warrant further investigations with appropriate adjustments for ecological and bacteriological factors.     

Pr-SNTX,a short-chain three-finger toxin from Papuan pigmy mulga snake,is an antagonist of muscle-type nicotinic acetylcholine receptor (α2βδε)

Three-finger toxins (3FTxs) are one of the major components in snake venoms. In this study, we isolated a cDNA encoding a short-chain 3FTx, Pr-SNTX, from Pseudechis rossignolii. The amino acid sequence of Pr-SNTX is nearly identical to that of its ortholog in Pseudechis australis. Pr-SNTX protein inhibited muscle-type (α₂βδε), but not neuronal α7 nicotinic acetylcholine receptor (nAChR) activity.     

Mapping of class alpha glutathione S-transferase 2 (GST-2) genes to the vicinity of the d locus on mouse chromosome 9

Recombinant inbred strains of mice were used to localize the genes coding for the class alpha glutathione S-transferase 2 (Gst-2). The genes showed three distinct strain distribution patterns, indicating that they occur in at least three clusters separable by recombination. All three clusters are located in the vicinity of the d locus on mouse chromosome 9, but two of them are closer to d than the third. Linked to Gst-2 on mouse chromosome 9 are two enzyme-encoding loci, Pgm-3 and Mod-1. The human counterparts of Gst-2, Pgm-3, and Mod-1 map to 6p12, 6q12, and 6q12, respectively. Thus, the pericentric region of human chromosome 6 has its homolog in the segment spanning Gst-2, Pgm-3, and Mod-1 on mouse chromosome 9. The fact that the syntenic group extends across the centromere of human chromosome 6 can best be explained by a pericentric inversion postulated to have taken place in the primate lineage leading to Catarhini.     

Novel lipase-catalyzed ring-opening copolymerization of lactide and trimethylene carbonate forming poly(ester carbonate)s.

Poly(lactide-co-trimethylene carbonate)s were prepared by the lipase-catalyzed ring-opening copolymerization of lactide and trimethylene carbonate having carbonate content from 0 to 100%. Their thermal properties and enzymatic degradability were measured. The L,L-, D,D- and D,L-lactides were copolymerized with trimethylene carbonate by porcine pancreatic lipase to produce random copolymers having molecular weights of up to 21000. The glass transition temperature (Tg of the copolymer was dependent on the carbonate content and the Tg values linearly decreased from 35 degrees C (polylactide) to -8 degrees C [poly(trimethylene carbonate)]. Among the lipases tested, the porcine pancreatic lipase and proteinase K showed biodegradability towards poly(ester-carbonate)s.     

Age-Related Changes of Myelin Proteins in the Rat Peripheral Nervous System

Age-related changes in amounts of myelin proteins from rat sciatic nerve or spinal root were analyzed by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE). In the aged peripheral nerve myelin, the relative amounts of band 105K and proteins X and Y increased, whereas those of proteins P0 and P1 and band 190K decreased. Band 105K purified by preparative SDS-PAGE exhibited three bands of 105K, 28K, and 21K at the second electrophoresis. A repeated SDS-PAGE did not improve the purity of bank 105K, but increased the ratio of 21K to 28K. Compared with P0 protein, band 105K has a very similar peptide map pattern and amino acid composition, as well as the identical NH2 terminal residue, isoleucine. These findings suggest that band 105K is an aggregate form of P0 protein and its fragment, 21K. The 21K protein is a distinct entity from X protein. The quantitative and qualitative alterations in myelin proteins, as we report here, may reflect continuing demyelination and remyelination in aged peripheral nerves.     

2,3,7,8-Tetrachlorodibenzo-p-dioxin causes elevation of the levels of the protein tyrosine kinase pp60c-src

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has been found to cause increases in cellular levels of pp60^src, a protein tyrosine kinase in hepatocytes from the rat and guinea pig, in the thymus of the mouse in vivo and in NIH-3T3 mouse fibroblast cell lines in vitro. Such cellular changes take place in vivo at early stages of TCDD poisoning (as early as one day after treatment in the case of mouse thymus) and at very low doses (single intraperitoneal injections of 1 μg/kg for guinea pigs, 25 μg/ kg for rats, and 30 μg/kg for mice). In addition such an effect of TCDD was observed only in a TCDD-responsive mouse strain but not in a nonresponsive strain. This effect of TCDD is a long-lasting one (eg, even 25 days after single dosing, the levels of pp60^src in the hepatic membrane remained high). In vitro this effect was observed in a wild-type 3T3 cell line but was more pronounced in one of the transfected lines with a v-src gene, a virus-derived oncogene known to code for pp60^src protein.     

Distribution of Acid Proteinase Activity in Molluscs

Acid proteinases with an optimum around pH 3 were demontrated in various tissues of 12 molluscan species. Enzymes strongly inhibited by pepstatin were predominant and the molecular weights of those from two species were in the region of 38,000–68,000, suggesting that they were cathepsin D-type proteinases.