Respiration-dependent primary Na+ pump in halophilic marine bacterium, Alcaligenes strain 201

AbstractThe inverted membrane vesicles of marine bacterium Alcaligenes strain 201 generated inside positive membrane potential and accumulated Na+ on the energization with NADH. Both the generation of membrane potential and the accumulation of Na+ were resistant to a proton conductor, carbonyl cyanide m-chlorophenylhydrazone. Collapse of the membrane potential by valinomycin resulted in the stimulation of Na+ accumulation. It was concluded that Alcaligenes strain 201 possesses a respiratory Na+ pump which is analogous to that of Vibrio alginolyticus.Inverted vesicle; Na+ pump; Marine bacteria; Respiratory chai

Sorting of lipoproteins to the outer membrane in E. coli

AbstractEscherichia coli lipoproteins are anchored to the periplasmic surface of the inner or outer membrane depending on the sorting signal. An ATP-binding cassette (ABC) transporter, LolCDE, releases outer membrane-specific lipoproteins from the inner membrane, causing the formation of a complex between the released lipoproteins and the periplasmic molecular chaperone LolA. When this complex interacts with outer membrane receptor LolB, the lipoproteins are transferred from LolA to LolB and then localized to the outer membrane. The structures of LolA and LolB are remarkably similar to each other. Both have a hydrophobic cavity consisting of an unclosed β-barrel and an α-helical lid. Structural differences between the two proteins reveal the molecular mechanisms underlying the energy-independent transfer of lipoproteins from LolA to LolB. Strong inner membrane retention of lipoproteins occurs with Asp at position 2 and a few limited residues at position 3. The inner membrane retention signal functions as a Lol avoidance signal and inhibits the recognition of lipoproteins by LolCDE, thereby causing their retention in the inner membrane. The positive charge of phosphatidylethanolamine and the negative charge of Asp at position 2 are essential for Lol avoidance. The Lol avoidance signal is speculated to cause the formation of a tight lipoprotein–phosphatidylethanolamine complex that has five acyl chains and therefore cannot be recognized by LolCDE

An ABC transporter mediating the membrane detachment of bacterial lipoproteins depending on their sorting signals

AbstractBacterial lipoproteins are anchored to membranes through a lipid moiety attached to the N-terminal Cys. Escherichia coli possesses more than 90 species of lipoproteins, most of which are localized in the outer membrane and others in the inner membrane. Sorting of lipoproteins to the outer membrane requires the Lol system comprising five Lol proteins. An ATP-binding cassette transporter, LolCDE, initiates the lipoprotein sorting by mediating the detachment of outer membrane-specific lipoproteins from the inner membrane. LolCDE does not recognize lipoproteins possessing Asp at position 2, which therefore remain anchored to the inner membrane. We will discuss the mechanism of LolCDE based on data obtained through in vitro experiments

The secG deletion mutation of Escherichia coli is suppressed by expression of a novel regulatory gene of Bacillus subtilis

AbstractSecG, a membrane component of E. coli protein translocase, stimulates the translocation of proteins across the cell membrane through the cycle of topology inversion, which is coupled to the membrane-insertion and deinsertion cycle of SecA [Nishiyama et al. (1996) Cell 85, 71–81]. A gene of B. subtilis able to suppress the cold-sensitive phenotype of the secG deletion mutant of E. coli was cloned and found to encode a novel regulatory protein, ScgR. Similarity search revealed homology with known proteins such as GlnR of B. subtilis. Plasmid-encoded ScgR stimulated protein translocation in the deletion mutant. ScgR increased the proportion of cardiolipin at the expense of phosphatidylglycerol, but did not affect the composition of other lipid components of the cell, suggesting that the increased cardiolipin level compensates for the SecG function and thereby stimulates protein translocation

An Unbiased CO Survey Toward the Northern Region of the Small Magellanic Cloud with the Atacama Compact Array. II. CO Cloud Catalog

The nature of molecular clouds and their statistical behavior in sub-solar metallicity environments are not fully explored yet. We analyzed an unbiased CO($J$ = 2-1) survey data at a spatial resolution of $\sim$2 pc in the northern region of the Small Magellanic Cloud (SMC) with the Atacama Compact Array to characterize the CO cloud properties. A cloud decomposition analysis identified 426 spatially/velocity-independent CO clouds and their substructures. Based on the cross-matching with known infrared catalogs by Spitzer and Herschel, more than 90% CO clouds show spatial correlations with point sources. We investigated the basic properties of the CO clouds and found that the radius-velocity linewidth ($R$-$\sigma_{v}$) relation follows the Milky Way (MW) like power-low exponent, but the intercept is $\sim$1.5 times lower than that in the MW. The mass functions ($dN/dM$) of the CO luminosity and virial mass are characterized by an exponent of $\sim$1.7, which is consistent with previously reported values in the Large Magellanic Cloud and MW.Comment: 18 pages, 9 figures. Accepted for publication in The Astrophysical Journa

Abdominoperineal Resection for Unexpected Distal Intramural Spreading of Rectal Cancer

Introduction: In rectal cancer, distal intramural spread may sometimes occur, but a maximum extent of distal spread of > 6 cm is very rare. Case Presentation: A 65-year-old Japanese male with an advanced rectal cancer tumor with para-aortic lymph node metastasis was admitted. We performed a low anterior resection with lymphadenectomy, but the intraoperative frozen-section analysis of margins revealed malignant cell positivity; we, therefore, performed an abdominoperineal resection. Pathological findings showed that the maximum extent of distal spread was 6 cm. After 12 courses of FOLFOX4 as adjuvant chemotherapy, abdominal computed tomography revealed whole lymph node metastases, including Virchow’s node. Though FOLFIRI + panitumumab was started, he was not eligible for additional chemotherapy after 10 cycles. Conclusion: An intraoperative frozen pathology examination was helpful for the additional resection, when unexpected distal spreading had occurred in rectal cancer. The evidence of a distal negative margin should not be underestimated

The Japanese space gravitational wave antenna; DECIGO

DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. DECIGO is expected to open a new window of observation for gravitational wave astronomy especially between 0.1 Hz and 10 Hz, revealing various mysteries of the universe such as dark energy, formation mechanism of supermassive black holes, and inflation of the universe. The pre-conceptual design of DECIGO consists of three drag-free spacecraft, whose relative displacements are measured by a differential Fabry– Perot Michelson interferometer. We plan to launch two missions, DECIGO pathfinder and pre- DECIGO first and finally DECIGO in 2024

Molecular Characteristics of Extended-Spectrum Beta-Lactamases and qnr Determinants in Enterobacter Species from Japan

The incidence of extended-spectrum β-lactamases (ESBLs) has been increasing worldwide, but screening criteria for detection of ESBLs are not standardized for AmpC-producing Enterobacteriaceae such as Enterobacter species. In this study, we investigated the prevalence of ESBLs and/or AmpC β-lactamases in Japanese clinical isolates of Enterobacter spp. and the association of plasmid-mediated quinolone resistance (PMQR) determinants with ESBL producers. A total of 364 clinical isolates of Enterobacter spp. collected throughout Japan between November 2009 and January 2010 were studied. ESBL-producing strains were assessed by the CLSI confirmatory test and the boronic acid disk test. PCR and sequencing were performed to detect CTX-M, TEM, and SHV type ESBLs and PMQR determinants. For ESBL-producing Enterobacter spp., pulsed-field gel electrophoresis (PFGE) was performed using XbaI restriction enzyme. Of the 364 isolates, 22 (6.0%) were ESBL producers. Seven isolates of Enterobacter cloacae produced CTX-M-3, followed by two isolates producing SHV-12. Two isolates of Enterobacter aerogenes produced CTX-M-2. Of the 22 ESBL producers, 21 had the AmpC enzyme, and six met the criteria for ESBL production in the boronic acid test. We found a significant association of qnrS with CTX-M-3-producing E. cloacae. The 11 ESBL-producing Enterobacter spp. possessing blaCTX-M, blaSHV, or blaTEM were divided into six unique PFGE types. This is the first report about the prevalence of qnr determinants among ESBL-producing Enterobacter spp. from Japan. Our results suggest that ESBL-producing Enterobacter spp. with qnr determinants are spreading in Japan