西沙珊瑚鍶溫度計: 便捷高精度海洋古水溫代用指標

Strontium concentrations in modem Porites coral from XishaIslands were determined by precise thermal ionization mass spectrometry. The coral skeleton grew in the period from 1976 to 1994. The results indicate that the variability of coral Sr is periodically at annual cycles, and is in agreement with in situ measured sea surface temperature (SST). The calibration of Sr and SST with correlation coefficient r = -0. 94 has been developed at monthly sampling resolution. In addition, maximum and minimum seasonal monthly Sr and SST values were also regressed for the 18-year interval, and the correlation coefficient is -0. 98. The error of this Sr thermometer is better than 0. 5 ℃.西沙群島現代濱珊瑚1976～1994年生長期間Sr含量的高精度熱電離質譜測定結果表明，Sr含量隨季節發生周期性的變化，并與當地同期實測海水月平均溫度變化相吻合，其Sr含量與實測海水溫度相關系數為-0.94。這18年冬夏季極端Sr含量與同期月溫的相關系數可高達-0.98。Sr溫度計誤差小于0.5℃。published_or_final_versio

南海北部珊瑚Ba/Ca比值的季节变化及其环境意义

利用等离子体质谱技术分析了取自海南岛南部沿岸的现代滨珊瑚高分辨率的Ba／Ca比值。结果表明，该珊瑚的Ba／Ca比值具有明显的双峰态的季节变化，其中春季和秋季Ba／Ca比值较高，而冬、夏两季则较低。海南岛南部及邻近地区季节降雨的变化所控制的陆源Ba输入是这些珊瑚Ba／Ca比值变化的重要控制因素，而该区夏季相对较高的表层海水生产力可能也对其有重要影响。High-resolution Ba/Ca ratios of a modern Porites coral from Sanya Bay, offshore of Hainan Island, were measured by ICP-MS. The results exhibit seasonal periodical ventilation of the coralline Ba/Ca ratios with higher Ba/ca ratios in spring and autumn and lower in winter and summer. variation of the terrestrial Ba flux to this area,which was controlled by seasonal precipitation of Southern Hainan Island and surmunded areas, is the key role to these Ba/Ca patterns. On the other hand, the relatively high surface productivity of the area in summer may contribute to the lower Ba/Ca ratios of the coral.postprin

Preliminary study on TIMS U-Th dating technique and their application

Thermal ionization mass spectrometry (TIMS) U-Th technique in dating purecarbonate has been established in our laboratory and was used to determine the ages of the Holocene coral samples from the South China Sea and a National Reference Material of uranium-series, GBW04413. The TIMS results of GBW04413 are in good agreement with their reference data determined from α-couning, indication that the ages by TIMS U-Th method are reliable. The TIMS ages of the coral samples older than 5ka have slightly older TIMS U-Th ages than their [14] C ages, which agrees with previous studies [12, 13, 16].尝试了用热电离质谱方法测定南海第四纪珊瑚的U- Th 年龄, 并利用国家铀系年龄标准物质GBW04413 来监测分析结果的合理性。结果显示, GBW04413 的TIMS 年龄与作为推荐值的A记数方法测定结果一致, 反映出其可靠性; 而年龄在1ka 左右的珊瑚样品的TIMS 年龄与14C 年龄一致, >5ka 样品的TIMS 年龄老于14C 年龄, 体现两种方法的系统差别。published_or_final_versio

Coralline Sr/Ca and Mg/Ca thermometer for the northern South China Sea: calibration and primary application high resolution on high-resolution SST reconstructing

利用全谱直读等离子体光谱(ICP2AES) 的分析方法精确分析了南海珊瑚的SrPCa 和MgPCa 比值,结合实测表层海水温度(SST),标定了海南岛南部三亚海域和西沙海域两个滨珊瑚的SrPCa 和MgPCa 温度计。在此基础上,尝试对两个南海北部全新世时期的珊瑚进行SST记录重建。结果显示约540aB.P. (小冰期) 西沙海域夏季月均SST 较现代低约1℃,而约6 500aB.P. (大暖期) 海南岛三亚海域夏季月均SST则高出现代1.0～1.5℃。The method for precisely and simultaneously measuring the coralline Sr/Ca and Mg/Ca ratios was established using inductively coupled plasma atomic emission spectrometry (ICP-AES). Using this method, the high-resolution Sr/Ca and Mg/Ca ratios of two Porites lutea from Sanya, South Hainan Island and Xisha Islands were measured. By comparing to the instrumentally measured sea surface temperatures in these two areas, the coralline Sr/Ca thermometer and the Mg/Ca thermometer were calibrated. These two thermometers can provide SST records with an error bar < 0.2℃, and they are suitable for high-resolution SST reconstructions in these areas. Based on these two thermometers, two short SST records were reconstructed from two Holocene Porites corals of the northern South China Sea. The results indicated that the monthly summer SSTs in Xisha Islands at about 540 years ago (the Little Ice Age) were 1℃ lower than that at present, and the monthly summer SSTs in Sanya, southern Hainan Island at 6 500 years ago (the Megathermal) were about 1℃ to 1 5℃ higher than that at present.published_or_final_versio

Sweet Taste Receptor Expressed in Pancreatic β-Cells Activates the Calcium and Cyclic AMP Signaling Systems and Stimulates Insulin Secretion

BACKGROUND:Sweet taste receptor is expressed in the taste buds and enteroendocrine cells acting as a sugar sensor. We investigated the expression and function of the sweet taste receptor in MIN6 cells and mouse islets. METHODOLOGY/PRINCIPAL FINDINGS:The expression of the sweet taste receptor was determined by RT-PCR and immunohistochemistry. Changes in cytoplasmic Ca(2+) ([Ca(2+)](c)) and cAMP ([cAMP](c)) were monitored in MIN6 cells using fura-2 and Epac1-camps. Activation of protein kinase C was monitored by measuring translocation of MARCKS-GFP. Insulin was measured by radioimmunoassay. mRNA for T1R2, T1R3, and gustducin was expressed in MIN6 cells. In these cells, artificial sweeteners such as sucralose, succharin, and acesulfame-K increased insulin secretion and augmented secretion induced by glucose. Sucralose increased biphasic increase in [Ca(2+)](c). The second sustained phase was blocked by removal of extracellular calcium and addition of nifedipine. An inhibitor of inositol(1, 4, 5)-trisphophate receptor, 2-aminoethoxydiphenyl borate, blocked both phases of [Ca(2+)](c) response. The effect of sucralose on [Ca(2+)](c) was inhibited by gurmarin, an inhibitor of the sweet taste receptor, but not affected by a G(q) inhibitor. Sucralose also induced sustained elevation of [cAMP](c), which was only partially inhibited by removal of extracellular calcium and nifedipine. Finally, mouse islets expressed T1R2 and T1R3, and artificial sweeteners stimulated insulin secretion. CONCLUSIONS:Sweet taste receptor is expressed in beta-cells, and activation of this receptor induces insulin secretion by Ca(2+) and cAMP-dependent mechanisms

Enhancing Production of Bio-Isoprene Using Hybrid MVA Pathway and Isoprene Synthase in E. coli

The depleting petroleum reserve, increasingly severe energy crisis, and global climate change are reigniting enthusiasm for seeking sustainable technologies to replace petroleum as a source of fuel and chemicals. In this paper, the efficiency of the MVA pathway on isoprene production has been improved as follows: firstly, in order to increase MVA production, the source of the “upper pathway” which contains HMG-CoA synthase, acetyl-CoA acetyltransferase and HMG-CoA reductase to covert acetyl-CoA into MVA has been changed from Saccharomyces cerevisiae to Enterococcus faecalis; secondly, to further enhance the production of MVA and isoprene, a alanine 110 of the mvaS gene has been mutated to a glycine. The final genetic strain YJM25 containing the optimized MVA pathway and isoprene synthase from Populus alba can accumulate isoprene up to 6.3 g/L after 40 h of fed-batch cultivation

The prevalence of hyperuricemia in China: a meta-analysis

<p>Abstract</p> <p>Background</p> <p>The prevalence of hyperuricemia varied in different populations and it appeared to be increasing in the past decades. Recent studies suggest that hyperuricemia is an independent risk factor for cardiovascular disease. However, there has not yet been a systematic analysis of the prevalence of hyperuricemia in China.</p> <p>Methods</p> <p>Epidemiological investigations on hyperuricemia in China published in journals were identified manually and on-line by using CBMDISC, Chongqing VIP database and CNKI database. Those Reported in English journals were identified using MEDLINE database. Selected studies had to describe an original study defined by strict screening and diagnostic criteria. The fixed effects model or random effects model was employed according to statistical test for homogeneity.</p> <p>Results</p> <p>Fifty-nine studies were selected, the statistical information of which was collected for systematic analysis. The results showed that the pooled prevalence of hyperuricemia in male was 21.6% (95%CI: 18.9%-24.6%), but it was only 8.6% (95%CI: 8.2%-10.2%) in female. It was found that thirty years was the risk point age in male and it was fifty years in female.</p> <p>Conclusions</p> <p>The prevalence of hyperuricemia is different as the period of age and it increases after 30 years in male and 50 in female. Interventions are necessary to change the risk factors before the key age which is 30 years in male and 50 in female.</p

A Cross-Species Analysis of MicroRNAs in the Developing Avian Face

Higher vertebrates use similar genetic tools to derive very different facial features. This diversity is believed to occur through temporal, spatial and species-specific changes in gene expression within cranial neural crest (NC) cells. These contribute to the facial skeleton and contain species-specific information that drives morphological variation. A few signaling molecules and transcription factors are known to play important roles in these processes, but little is known regarding the role of micro-RNAs (miRNAs). We have identified and compared all miRNAs expressed in cranial NC cells from three avian species (chicken, duck, and quail) before and after species-specific facial distinctions occur. We identified 170 differentially expressed miRNAs. These include thirty-five novel chicken orthologs of previously described miRNAs, and six avian-specific miRNAs. Five of these avian-specific miRNAs are conserved over 120 million years of avian evolution, from ratites to galliforms, and their predicted target mRNAs include many components of Wnt signaling. Previous work indicates that mRNA gene expression in NC cells is relatively static during stages when the beak acquires species-specific morphologies. However, miRNA expression is remarkably dynamic within this timeframe, suggesting that the timing of specific developmental transitions is altered in birds with different beak shapes. We evaluated one miRNA:mRNA target pair and found that the cell cycle regulator p27KIP1 is a likely target of miR-222 in frontonasal NC cells, and that the timing of this interaction correlates with the onset of phenotypic variation. Our comparative genomic approach is the first comprehensive analysis of miRNAs in the developing facial primordial, and in species-specific facial development

The utility of the new generation of humanized mice to study HIV-1 infection: transmission, prevention, pathogenesis, and treatment

Substantial improvements have been made in recent years in the ability to engraft human cells and tissues into immunodeficient mice. The use of human hematopoietic stem cells (HSCs) leads to multi-lineage human hematopoiesis accompanied by production of a variety of human immune cell types. Population of murine primary and secondary lymphoid organs with human cells occurs, and long-term engraftment has been achieved. Engrafted cells are capable of producing human innate and adaptive immune responses, making these models the most physiologically relevant humanized animal models to date. New models have been successfully infected by a variety of strains of Human Immunodeficiency Virus Type 1 (HIV-1), accompanied by virus replication in lymphoid and non-lymphoid organs, including the gut-associated lymphoid tissue, the male and female reproductive tracts, and the brain. Multiple forms of virus-induced pathogenesis are present, and human T cell and antibody responses to HIV-1 are detected. These humanized mice are susceptible to a high rate of rectal and vaginal transmission of HIV-1 across an intact epithelium, indicating the potential to study vaccines and microbicides. Antiviral drugs, siRNAs, and hematopoietic stem cell gene therapy strategies have all been shown to be effective at reducing viral load and preventing or reversing helper T cell loss in humanized mice, indicating that they will serve as an important preclinical model to study new therapeutic modalities. HIV-1 has also been shown to evolve in response to selective pressures in humanized mice, thus showing that the model will be useful to study and/or predict viral evolution in response to drug or immune pressures. The purpose of this review is to summarize the findings reported to date on all new humanized mouse models (those transplanted with human HSCs) in regards to HIV-1 sexual transmission, pathogenesis, anti-HIV-1 immune responses, viral evolution, pre- and post-exposure prophylaxis, and gene therapeutic strategies