Re-Os isotope and platinum group elements of a FOcal ZOne mantle source, Louisville Seamounts Chain, Pacific ocean

The Louisville Seamount Chain (LSC) is, besides the Hawaiian-Emperor Chain, one of the longest-lived hotspot traces. We report here the first Re-Os isotope and platinum group element (PGE) data for Canopus, Rigil, and Burton Guyots along the chain, which were drilled during IODP Expedition 330. The LSC basalts possess (187Os/188Os)i = 0.1245–0.1314 that are remarkably homogeneous and do not vary with age. A Re-Os isochron age of 64.9 ± 3.2 Ma was obtained for Burton seamount (the youngest of the three seamounts drilled), consistent with 40Ar-39Ar data. Isochron-derived initial 187Os/188Os ratio of 0.1272 ± 0.0008, together with data for olivines (0.1271–0.1275), are within the estimated primitive mantle values. This (187Os/188Os)i range is similar to those of Rarotonga (0.124–0.139) and Samoan shield (0.1276–0.1313) basalts and lower than those of Cook-Austral (0.136–0.155) and Hawaiian shield (0.1283–0.1578) basalts, suggesting little or no recycled component in the LSC mantle source. The PGE data of LSC basalts are distinct from those of oceanic lower crust. Variation in PGE patterns can be largely explained by different low degrees of melting under sulfide-saturated conditions of the same relatively fertile mantle source, consistent with their primitive mantle-like Os and primordial Ne isotope signatures. The PGE patterns and the low 187Os/188Os composition of LSC basalts contrast with those of Ontong Java Plateau (OJP) tholeiites. We conclude that the Re-Os isotope and PGE composition of LSC basalts reflect a relatively pure deep-sourced common mantle sampled by some ocean island basalts but is not discernible in the composition of OJP tholeiites

A Requirement of TolC and MDR Efflux Pumps for Acid Adaptation and GadAB Induction in Escherichia coli

BACKGROUND: The TolC outer membrane channel is a key component of several multidrug resistance (MDR) efflux pumps driven by H(+) transport in Escherichia coli. While tolC expression is under the regulation of the EvgA-Gad acid resistance regulon, the role of TolC in growth at low pH and extreme-acid survival is unknown. METHODS AND PRINCIPAL FINDINGS: TolC was required for extreme-acid survival (pH 2) of strain W3110 grown aerobically to stationary phase. A tolC deletion decreased extreme-acid survival (acid resistance) of aerated pH 7.0-grown cells by 10(5)-fold and of pH 5.5-grown cells by 10-fold. The requirement was specific for acid resistance since a tolC defect had no effect on aerobic survival in extreme base (pH 10). TolC was required for expression of glutamate decarboxylase (GadA, GadB), a key component of glutamate-dependent acid resistance (Gad). TolC was also required for maximal exponential growth of E. coli K-12 W3110, in LBK medium buffered at pH 4.5-6.0, but not at pH 6.5-8.5. The TolC growth requirement in moderate acid was independent of Gad. TolC-associated pump components EmrB and MdtB contributed to survival in extreme acid (pH 2), but were not required for growth at pH 5. A mutant lacking the known TolC-associated efflux pumps (acrB, acrD, emrB, emrY, macB, mdtC, mdtF, acrEF) showed no growth defect at acidic pH and a relatively small decrease in extreme-acid survival when pre-grown at pH 5.5. CONCLUSIONS: TolC and proton-driven MDR efflux pump components EmrB and MdtB contribute to E. coli survival in extreme acid and TolC is required for maximal growth rates below pH 6.5. The TolC enhancement of extreme-acid survival includes Gad induction, but TolC-dependent growth rates below pH 6.5 do not involve Gad. That MDR resistance can enhance growth and survival in acid is an important consideration for enteric organisms passing through the acidic stomach

TolC-Dependent Exclusion of Porphyrins in Escherichia coli▿

We found that Escherichia coli tolC mutants showed increased sensitivity to 5-aminolevulinic acid (ALA), a precursor of porphyrins. The tolC mutant cells grown in the presence of ALA showed a reddish brown color under visible light and a strong red fluorescence under near-UV irradiation. Fluorescence spectrometry and high-performance liquid chromatography analysis showed that the tolC mutant cells grown in the presence of ALA accumulated a large amount of coproporphyrin(ogen) intracellularly. In contrast, the wild-type cells produced coproporphyrin extracellularly. The tolC mutant cells grown in the presence of ALA, which were capable of surviving in the dark, were killed by near-UV irradiation, suggesting that the intracellular coproporphyrin(ogen) renders these cells photosensitive. These results suggest that the TolC-dependent efflux system is involved in the exclusion of porphyrin(ogen)s in E. coli

N‑Heterocyclic Carbene Complexes of Three- and Four-Coordinate Fe(I)

N-heterocyclic carbene complexes of three- and four-coordinate Fe­(I), [Fe­(L^R)₄]­[PF₆] (L^R = 1,3-R₂-4,5-dimethylimidazol-2-ylidene, R = Me (<b>2</b>), Et (<b>3</b>), ⁱPr (<b>4</b>)) and [Fe­(L^Mes)₂(THF)]­[PF₆] (<b>5</b>) (L^Mes = 1,3-bis­(2,4,6-trimethylphenyl)­imidazol-2-ylidene), were synthesized from successive reactions of [Fe­(toluene)₂]­[PF₆]₂ with 1 equiv of KC₈ and L^R (4 equiv for R = Me, Et, ⁱPr; 2 equiv for R = Mes). The coordination geometry of the iron atom in these complexes varies depending on the nature of the R group in L^R: a tetrahedral geometry was observed for <b>2</b>, a square-planar one for <b>3</b> and <b>4</b>, and a three-coordinate T-shaped one for <b>5</b>. In solution, <b>4</b> releases L^iPr ligand(s), while the L^R ligands of the other Fe­(I) complexes remain firmly bound. Tetrahedral <b>2</b> and T-shaped <b>5</b> contain a high-spin (<i>S</i> = ³/₂) Fe­(I) center, whereas square-planar <b>3</b> and <b>4</b> contain Fe­(I) in the low-spin state (<i>S</i> = ¹/₂)

The Use of Electronic Medical Record Data to Analyze the Association Between Atrial Fibrillation and Birth Month

 Objectives: The pineal gland completes cell differentiation and growth during infancy, with the secretory capacity for melatonin also determined during this time. Notably, melatonin secretion may be involved in the association between cardiovascular disease risk and birth month. Here, we investigated the association between atrial fibrillation in cardiovascular disease and birth month. This association might present valuable information on the environment during infancy that can reduce future disease risk. Methods: We retrospectively extracted birth date data from 6,016 patients with atrial fibrillation (3,876 males; 2,140 females) from our electronic medical records. The number of live births in Japan fluctuates seasonally. Therefore, we corrected the number of patients for each birth month based on a Japanese population survey report. Then a test of the significance of the association between atrial fibrillation and birth month was performed using a chi-square test. In addition, we compared the results of an analysis of patient data with that of simulated data that showed no association with birth month.  Results: The deviations of birth month were not significant (overall: p = 0.631, males: p = 0.842, females: p = 0.333). The number of female patients born in the first quarter of the year was slightly higher than those born in the other quarters of the year (p = 0.030). However, by comparing the magnitudes of dispersion in the simulated data, it seems that this finding was mere coincidence.  Conclusion: An association between atrial fibrillation and birth month could not be confirmed in our Japanese study. This might be due to differences in ethnicity.

The Use of Electronic Medical Record Data to Analyze the Association Between Atrial Fibrillation and Birth Month

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The Use of Electronic Medical Record Data to Analyze the Association Between Atrial Fibrillation and Birth Month

 Objectives: The pineal gland completes cell differentiation and growth during infancy, with the secretory capacity for melatonin also determined during this time. Notably, melatonin secretion may be involved in the association between cardiovascular disease risk and birth month. Here, we investigated the association between atrial fibrillation in cardiovascular disease and birth month. This association might present valuable information on the environment during infancy that can reduce future disease risk. Methods: We retrospectively extracted birth date data from 6,016 patients with atrial fibrillation (3,876 males; 2,140 females) from our electronic medical records. The number of live births in Japan fluctuates seasonally. Therefore, we corrected the number of patients for each birth month based on a Japanese population survey report. Then a test of the significance of the association between atrial fibrillation and birth month was performed using a chi-square test. In addition, we compared the results of an analysis of patient data with that of simulated data that showed no association with birth month.  Results: The deviations of birth month were not significant (overall: p = 0.631, males: p = 0.842, females: p = 0.333). The number of female patients born in the first quarter of the year was slightly higher than those born in the other quarters of the year (p = 0.030). However, by comparing the magnitudes of dispersion in the simulated data, it seems that this finding was mere coincidence.  Conclusion: An association between atrial fibrillation and birth month could not be confirmed in our Japanese study. This might be due to differences in ethnicity.

N‑Heterocyclic Carbene Complexes of Three- and Four-Coordinate Fe(I)

N-heterocyclic carbene complexes of three- and four-coordinate Fe­(I), [Fe­(L^R)₄]­[PF₆] (L^R = 1,3-R₂-4,5-dimethylimidazol-2-ylidene, R = Me (<b>2</b>), Et (<b>3</b>), ⁱPr (<b>4</b>)) and [Fe­(L^Mes)₂(THF)]­[PF₆] (<b>5</b>) (L^Mes = 1,3-bis­(2,4,6-trimethylphenyl)­imidazol-2-ylidene), were synthesized from successive reactions of [Fe­(toluene)₂]­[PF₆]₂ with 1 equiv of KC₈ and L^R (4 equiv for R = Me, Et, ⁱPr; 2 equiv for R = Mes). The coordination geometry of the iron atom in these complexes varies depending on the nature of the R group in L^R: a tetrahedral geometry was observed for <b>2</b>, a square-planar one for <b>3</b> and <b>4</b>, and a three-coordinate T-shaped one for <b>5</b>. In solution, <b>4</b> releases L^iPr ligand(s), while the L^R ligands of the other Fe­(I) complexes remain firmly bound. Tetrahedral <b>2</b> and T-shaped <b>5</b> contain a high-spin (<i>S</i> = ³/₂) Fe­(I) center, whereas square-planar <b>3</b> and <b>4</b> contain Fe­(I) in the low-spin state (<i>S</i> = ¹/₂)