Waseda University

About: Waseda University is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Catalysis & Large Hadron Collider. The organization has 24220 authors who have published 46859 publications receiving 837855 citations. The organization is also known as: Waseda daigaku & Sōdai.

Identification of acetate- or methanol-assimilating bacteria under nitrate-reducing conditions by stable-isotope probing.

Abstract: Stable-isotope probing (SIP) was used to identify acetate- or methanol-assimilating bacteria under nitrate-reducing conditions in activated sludge. A sludge sample obtained from wastewater treatment systems was incubated in a denitrifying batch reactor fed with synthetic wastewater containing [13C]acetate or [13C]methanol as the main carbon source and nitrate as the electron acceptor. We analyzed how growth of bacterial populations was stimulated by acetate or methanol as the external carbon source in nitrogen-removal systems. Most of the acetate- or methanol-assimilating bacteria identified by SIP have been known as denitrifiers in wastewater treatment systems. When acetate was used as the carbon source, 16S rRNA gene sequences retrieved from 13C-labeled DNA were closely related to the 16S rRNA genes of Comamonadaceae (e.g., Comamonas and Acidovorax) and Rhodocyclaceae (e.g., Thauera and Dechloromonas) of the Betaproteobacteria, and Rhodobacteraceae (e.g., Paracoccus and Rhodobacter) of the Alphaproteobacteria. When methanol was used as the carbon source, 16S rRNA gene sequences retrieved from 13C-DNA were affiliated with Methylophilaceae (e.g., Methylophilus, Methylobacillus, and Aminomonas) and Hyphomicrobiaceae. Rarefaction curves for clones retrieved from 13C-DNA showed that the diversity levels for methanol-assimilating bacteria were considerably lower than those for acetate-assimilating bacteria. Furthermore, we characterized nitrite reductase genes (nirS and nirK) as functional marker genes for denitrifier communities in acetate- or methanol-assimilating populations and detected the nirS or nirK sequence related to that of some known pure cultures, such as Alcaligenes, Hyphomicrobium, and Thauera. However, most of the nirS or nirK sequences retrieved from 13C-DNA were clustered in some unidentified groups. On the basis of 16S rRNA gene clone libraries retrieved from 13C-DNA, these unidentified nir sequences might be identified by examining the nir gene in candidates for true denitrifiers (e.g., the families Comamonadaceae, Hyphomicrobiaceae, Methylophilaceae, and Rhodobacteraceae).

Optimal emission tax with endogenous location choice of duopolistic firms

Abstract: This study explores an optimal (pre-committed or ex-ante) environmental tax policy in a three-stage game in which polluting firms strategically choose the location of their plants after the government has chosen the optimal emission tax rate. We show not only that the optimal emission tax is non-decreasing with the declining cost of relocation (e.g., setup or fixed costs), or else, the progress of globalization but also that the firms may move back their relocated plants to the home country, causing the resulting welfare to decline. As a consequence, the domestic welfare varies in a non-monotonic way. We also show that such a counterintuitive non-monotonic relationship does not arise under time-consistent (ex-post) emission taxes.

Mesoporous Pt nanospheres with designed pore surface as highly active electrocatalyst

Abstract: A novel strategy for large-scale synthesis of shape- and size-controlled mesoporous Pt nanospheres (MPNs) through a slow reduction reaction in the presence of surfactant is reported here for the first time. The slow reduction reaction exclusively results in well-defined mesoporous architectures distinctly different from the dendritic constructions reported previously. More importantly, abundant catalytically active sites are created on the highly accessible mesoporous surfaces by the selective adsorption of bromide ions. The MPNs prepared by using the new synthetic route not only show superior electrochemical performance toward methanol oxidation reaction and oxygen reduction reaction, but also exhibit extremely high structural thermostability, which makes them promising catalysts for industrial applications.

TGF-β drives epithelial-mesenchymal transition through δEF1-mediated downregulation of ESRP

Abstract: Epithelial-mesenchymal transition (EMT) is a crucial event in wound healing, tissue repair and cancer progression in adult tissues. We have recently shown that transforming growth factor (TGF)-β-induced EMT involves isoform switching of fibroblast growth factor receptors by alternative splicing. We performed a microarray-based analysis at single exon level to elucidate changes in splicing variants generated during TGF-β-induced EMT, and found that TGF-β induces broad alteration of splicing patterns by downregulating epithelial splicing regulatory proteins (ESRPs). This was achieved by TGF-β-mediated upregulation of δEF1 family proteins, δEF1 and SIP1. δEF1 and SIP1 each remarkably repressed ESRP2 transcription through binding to the ESRP2 promoter in NMuMG cells. Silencing of both δEF1 and SIP1, but not either alone, abolished the TGF-β-induced ESRP repression. The expression profiles of ESRPs were inversely related to those of δEF1 and SIP in human breast cancer cell lines and primary tumor specimens. Further, overexpression of ESRPs in TGF-β-treated cells resulted in restoration of the epithelial splicing profiles as well as attenuation of certain phenotypes of EMT. Therefore, δEF1 family proteins repress the expression of ESRPs to regulate alternative splicing during TGF-β-induced EMT and the progression of breast cancers.