Instability of Rts1 (Drug-Resistant Factor) Replicon: Stabilization by DNA Fragments Derived from Rts1

Rts1 is a large naturally occurring plasmid which has a kanamycin resistance gene and exhibits various temperature-sensitive phenotypes. A smaller derivative of plasmid, pOK, contains the Rts1 replicon and the kanamycin resistance gene of Rts1. This plasmid, pOK, is much more unstable than Rts1 at 42.5°C. A DNA fragment, G₃, 1590 nucleotides long from Rts1 DNA, stabilized pOK completely at 42.5°C but only in thecisconfiguration. G₃did not change the copy number of pOK. The pOK derivative containing G₃was destabilized by the presence of a compatible plasmid containing G₃. G₃has four inverted repeats, two 14-base direct repeats, and three ORFs. Smaller fragment of G₃also had a stabilization effect and these studies showed that the ORF does not play any role in stabilization.     

A Novel Fluorescent Probe That Senses the Physical State of Lipid Bilayers

Cell membrane lipids and proteins are heterogeneously distributed in the membrane plane. In recent years, much attention has been paid to the heterogeneous distribution of the lipid components, particularly the formation of cholesterol-rich domains that are thought to be important in signaling processes. This has led to renewed interest in the phase diagrams of complex lipid mixtures, such as three-component mixtures containing phospholipids and cholesterol. We report here a novel fluorescent probe (NBD-R595) that is useful for exploring the phase behaviors of one-, two-, and three-component large unilamellar vesicles. In one-component fluid-phase membranes, the probe has the expected spectral characteristic of monomeric 7-nitrobenzo-2-oxa-1,3-diazol, with a fluorescence maximum of 540 nm when excited at 470 nm. But below the gel-to-liquid crystalline phase transition temperature, an additional emission peak appears at ∼610 nm, because of Förster resonance energy transfer from NBD-R595 monomers to NBD-R595 Jelley aggregates of limited size formed by the association of 7-nitrobenzo-2-oxa-1,3-diazol moieties. This may be the first report of Förster resonance energy transfer from a single fluorophore in two different physical states. In a test of the probe, we found NBD-R595 to be remarkably sensitive to the molar composition of large unilamellar vesicles formed from cholesterol, distearoylphosphatidylcholine, and dioleoylphosphatidylcholine.     

Oxytocin Influences Male Sexual Activity via Non-synaptic Axonal Release in the Spinal Cord

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Tryptamine-based human β3-adrenergic receptor agonists. Part 2: SAR of the methylene derivatives

A series of tryptamine derivatives with modified sulfonamide were designed, synthesized, and evaluated for their ability to stimulate cAMP accumulation in CHO cells expressing the cloned human β₃-adrenergic receptor (AR). For this series of compounds, our objective was to symmetrize the α-position of the tryptamine moiety maintaining its activity and reducing the cost of production. Compound 11h, having m-aminobenzene, exhibited excellent agonistic activity for β₃-AR with excellent subtype selectivity.     

Dispersible chitosan particles showing bacteriostatic effect against Streptococcus mutans and their dental polishing effect

ABSTRACT

Nontoxic and biodegradable chitosan is potentially useful in various applications. We prepared submicron chitosan particles with high dispersibility in aqueous solution utilizing the electrostatic interaction phase separation method described in a previous report, but using citric acid as the polyvalent anionic compound instead of sodium sulfate. The submicron chitosan particles showed significant antibacterial activity and anti-adhesive action against Streptococcus mutans, even at around neutral pH. However, chitosan granules showed no antibacterial activity under the same conditions. The addition of the chitosan particles to dental polishing paste provided stainless steel discs (the same hardness as dental enamel) with a smoother surface than polishing paste without additives. In view of their submicron size and antibacterial activity, chitosan particles could potentially be multifunctional components of oral and dental cleaning materials.     

Studies on Streptococci: I. Distribution of Fecal Streptococci in Man

To understand the significance to the host of streptococci as part of the intestinal microflora, we first tried to investigate the distribution of human fecal streptococci on the species level. Of the selective media compared, KMN agar was more effective than the other media for the isolation of streptococci from human feces. We made an effort to improve streptococcal classification. Especially we used utilization of 1% pyruvate, 1% arginine, and 1% citrate for differentiation between Streptococcus faecalis and S. faecium. In a tellurite tolerance test, S. faecalis was distinguished more clearly from S. faecium in the medium containing 0.16 or 0.32% tellurite. We devised methods of presumptive identification of fecal streptococci from the results of the characteristics of 1,442 isolates. These methods enabled us to identify many strains rapidly. Different results in the distribution of species of streptococci between children and adults were observed. S. faecalis and S. faecium were isolated constantly from both groups. S. bovis and S. avium were isolated frequently from the feces of children. On the other hand, “viridans” streptococci, e.g. S. salivarius, S. mitis and S. MG-intermedius were present at a high frequency in, and no S. avium could be isolated from, the feces of adults.     

Soil moisture variability on a steep slope near a ridge in a forested mountain range, Shikoku, Japan: a model study

Variability in soil moisture on a steep slope near a ridge in a forested mountain range, Shikoku, Japan, was studied observationally and numerically. Vertically integrated soil moisture, from a depth of ?60 cm to the surface, W, was introduced as a key indicator, and its seasonal variation was analysed on a daily basis from August 2011 to August 2012. The “bucket with a bottom hole” (BBH) model of Teshima et al. (2006) was improved to consider the forest environment in simulating the variation in W. A “big-leaf” model was incorporated into the modified BBH model to estimate transpiration and interception by trees. The simulated soil moisture agreed reasonably with observed values on a daily to inter-seasonal timescale.