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Bacteriocin plasmid pPD1 in Enterococcus faecalis encodes a mating response to recipient-produced sex pheromone cPD1. Once a recipient acquires pPD1, transconjugants apparently shut off cPD1 activity in broth culture and no longer behave as recipients for pPD1. This event is performed by synthesis of the pheromone inhibitor iPD1 and also by repression of cPD1 production, the so-called ''pheromone shutdown.'' A 5.4-kb EcoRV-HincII segment of pPD1, which expressed iPD1 in Escherichia coli, was sequenced and found to be organized as traC-traB-traA-ipd; each open reading frame is analogous to that found in other pheromone plasmids, pAD1 and pCF10, and thus is designated in accordance with the nomenclature in pAD1. The ipd gene encodes a peptide consisting of 21 amino acids, in which the C-terminal eight residues correspond to iPD1. The putative TraC product has a strong similarity to oligopeptide-binding proteins found in other bacterial species, as do pheromone-binding proteins of pCF10 and pAD1. A strain carrying traC-disrupted pPD1 required a concentration of cPD1 fourfold higher than that needed by the wild-type strain for induction of sexual aggregation. These results suggest that the TraC product contributes to pheromone sensitivity as a pheromonebinding protein. A strain transformed with traB-disrupted pPD1 produced a high level of cPD1 similar to that produced by plasmid-free recipients and underwent self-induction. Thus, the TraB product contributes to cPD1 shutdown.Certain plasmids in Enterococcus faecalis encode a mating response to small-peptide sex pheromones secreted from potential recipient cells (for recent reviews, see references 4 and 5). The sex pheromone induces a surface adhesin, termed aggregation substance, which leads to sexual aggregation of recipient and donor cells (9,12,13,47). The formation of the mating aggregate facilitates the high-frequency transfer of plasmids in a liquid medium.The plasmid-free recipient secretes multiple pheromones (10). A given pheromone (cX) specifically activates the conjugal transfer system of the corresponding plasmid (pX). Once a recipient acquires the plasmid, it becomes a donor; however, it continues to behave as a recipient for other plasmids. The transconjugant donor no longer detectably secretes that pheromone, while the activity of other pheromones continues to be elaborated. Two kinds of genetic function can explain the disappearance of pheromone activity. One is the production of a peptide inhibitor (iX) competitive with the pheromone, and the other is repression of pheromone production, a so-called ''pheromone shutdown.'' To address this notion, we have developed a reverse-phase high-pressure liquid chromatography (HPLC) assay enabling us to quantitate absolute pheromone and inhibitor titers in the donor supernatant, where the pheromone and inhibitor coexist (33,35). The inhibitor data showed that the inhibitors iAD1 (30), iPD1 (31), iCF10 (35), and iAM373 (34) exist in the culture broth of donor cells carrying the corresponding plasmid, consistent ...

Requirements for flexible electronic substrate are successfully accomplished by green nanocomposite film fabricated with two natural components: glycol-modified biomass lignin and Li montmorillonite clay. In addition to these major components, a cross-linking polymer between the lignin is incorporated into montmorillonite. Multilayer-assembled structure is formed due to stacking nature of high aspect montmorillonite, resulting in thermal durability up to 573 K, low thermal expansion, and oxygen barrier property below measurable limit. Preannealing for montmorillonite and the cross-linking formation enhance moisture barrier property superior to that of industrial engineering plastics, polyimide. As a result, the film has advantages for electronic film substrate. Furthermore, these properties can be achieved at the drying temperature up to 503 K, while the polyimide films are difficult to fabricate by this temperature. In order to examine its applicability for substrate film, flexible electrodes are finely printed on it and touch sensor device can be constructed with rigid elements on the electrode. In consequence, this nanocomposite film is expected to contribute to production of functional materials, progresses in expansion of biomass usage with low energy consumption, and construction of environmental friendly flexible electronic devices.

In Nature, organized nanoscale structures such as proteins and enzymes are formed in aqueous media via intermolecular interactions between multicomponents. Supramolecular and self-assembling strategies provide versatile methods for the construction of artificial chemical architectures for controlling reaction rates and the specificities of chemical reactions, but most are designed in hydrophobic environments. The preparation of artificial catalysts that have potential in aqueous media mimicking natural enzymes such as hydrolases remains a great challenge in the fields of supramolecular chemistry. Herein, we describe that a dimeric Zn(2+) complex having a 2,2'-bipyridyl linker, cyanuric acid, and a Cu(2+) ion automatically assembles in an aqueous solution to form a 4:4:4 complex, which is stabilized by metal-ligand coordination bonds, π-π-stacking interactions, and hydrogen bonding and contains μ-Cu(2)(OH)(2) cores analogous to the catalytic centers of phosphatase, a dinuclear metalloenzyme. The 4:4:4 complex selectively accelerates the hydrolysis of a phosphate monoester, mono(4-nitrophenyl)phosphate, at neutral pH.

This is the first study revealing the differences in gut microbiota of captive dolphins among facilities. Our findings will provide valuable information for improving the health management of dolphins.