We have developed a new method for in situ measurement of Cu isotopic compositions of pure Cu metal and Cu-rich minerals using a near-infrared (NIR) femtosecond laser ablation (LA) system with a laser spot diameter of 15 mm, combined with multiple collector-inductively coupled plasma-mass spectrometry (MC-ICP-MS). The Cu-rich minerals include native copper (Cu), cuprite (Cu 2 O), chalcocite (Cu 2 S) and chalcopyrite (CuFeS 2 ). Time resolved analysis (TRA) was utilized for the acquisition of each individual analysis, and a standard-sample-standard bracketing technique was applied to correct the instrumental mass fractionation and drift. To evaluate the precision and accuracy of our laser ablation technique, Cu isotopic compositions of the same sample materials were also measured by conventional solution MC-ICP-MS using the same MC-ICP-MS system. The long-term analytical reproducibility of Cu isotopic ratio measurements of pure copper metal sample over a 6 month period using laser ablation analysis was 0.05& (2SD), which is comparable to that obtained by conventional solution MC-ICP-MS analysis (0.05&, 2SD). The copper isotopic compositions measured relative to NIST-SRM 976 Cu standard (pure Cu metal) both by laser and solution MC-ICP-MS techniques are in excellent agreement for pure Cu metal and native copper samples. Copper isotope ratios of cuprite samples could be determined using NIST-SRM 976 Cu standard, while matrixmatched standards are required for reliable in situ Cu isotope analysis of chalcocite and chalcopyrite samples. Repeated measurements of Cu isotope ratios for all samples provide an analytical precision of better than 0.14& (2SD). The femtosecond LA-MC-ICP-MS method provides a rapid and effective approach to determine the Cu isotopic composition of pure copper metal and typical copper ore minerals at analytical scales down to 15 mm, with comparable precision and accuracy to that attainable with conventional solution nebulization techniques, without requiring time-consuming chemical separation procedures.

Seafloor massive sulfides are a potential energy source for the support of chemosynthetic ecosystems in dark, deep-sea environments; however, little is known about microbial communities in these ecosystems, especially below the seafloor. In the present study, we performed culture-independent molecular analyses of sub-seafloor sulfide samples collected in the Southern Mariana Trough by drilling. The depth for the samples ranged from 0.52 m to 2.67 m below the seafloor. A combination of 16S rRNA and functional gene analyses suggested the presence of chemoautotrophs, sulfur-oxidizers, sulfate-reducers, iron-oxidizers and iron-reducers. In addition, mineralogical and thermodynamic analyses are consistent with chemosynthetic microbial communities sustained by sulfide minerals below the seafloor. Although distinct bacterial community compositions were found among the sub-seafloor sulfide samples and hydrothermally inactive sulfide chimneys on the seafloor collected from various areas, we also found common bacterial members at species level including the sulfur-oxidizers and sulfate-reducers, suggesting that the common members are widely distributed within massive sulfide deposits on and below the seafloor and play a key role in the ecosystem function.

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Nonalcoholic steatohepatitis (NASH) is a progressive form of nonalcoholic fatty liver disease (NAFLD) that can develop into liver cirrhosis and cancer. Elongation of very long chain fatty acids (ELOVL) family member 6 (Elovl6) is a microsomal enzyme that regulates the elongation of C12–16 saturated and monounsaturated fatty acids (FAs). We have previously shown that Elovl6 plays an important role in the development of hepatic insulin resistance and NASH by modifying FA composition. Recent studies have linked altered hepatic cholesterol homeostasis and cholesterol accumulation to the pathogenesis of NASH. In the present study, we further investigated the role of Elovl6 in the progression of lithogenic diet (LD)-induced steatohepatitis. We showed that the absence of Elovl6 suppresses hepatic lipid accumulation, plasma total cholesterol and total bile acid (BA) levels in LDL receptor-deficient (Ldlr−/−) mice challenged with a LD. The absence of Elovl6 also decreases hepatic inflammation, oxidative stress and liver injury, but increases the formation of cholesterol crystals in the less dilated gallbladder. These findings suggest that Elovl6-mediated changes in hepatic FA composition, especially oleic acid (C18:1n-9), control handling of hepatic cholesterol and BA, which protects against hepatotoxicity and steatohepatitis, but promotes gallstone formation in LD-fed Ldlr−/− mice.

which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. AbstractComponents and sulfur isotopic compositions of pyroclastic materials from the 2014 Mt. Ontake eruption were investigated. The volcanic ash samples were found to be composed of altered volcanic fragments, alunite, anhydrite, biotite, cristobalite, gypsum, ilmenite, kaolin minerals, native sulfur, orthopyroxene, plagioclase, potassium feldspar, pyrite, pyrophyllite, quartz, rutile, and smectite, and most of these minerals were likely derived from the acidic alteration zones of Mt. Ontake. The absence of juvenile material in the eruptive products indicates that the eruption was phreatic. The sulfur isotopic compositions of the water-leached sulfate, hydrochloric acid-leached sulfate, acetone-leached native sulfur, and pyrite of the samples indicate that these sulfur species were produced by disproportionation of magmatic SO 2 in the hydrothermal system at temperatures of 270-281 °C. This temperature range is consistent with that inferred from the hydrothermal mineral assemblage (e.g., pyrophyllite and rutile) in the 2014 pyroclastic materials (200-300 °C). Except for the sulfur isotopic compositions of anhydrite, which may have been altered by incorporation of sulfate minerals in a fumarolic area with lower sulfur isotopic values into the underground materials during the 1979 eruption, no significant differences in the mineral assemblages and sulfur isotopic compositions of the pyroclastic materials were identified between the products of the 2014 and 1979 Ontake phreatic eruptions, which suggests geochemical similarities in the underlying hydrothermal systems before the 2014 and 1979 eruptions.