Reverse micelle-based chemiluminescence system for quinine sulphate.

A new chemiluminescence (CL) method is proposed for the determination of quinine sulphate, which is based on the dichloromethane solvent extraction of the ion-pair complex of tetrachloroaurate (III) with quinine sulphate, and luminol CL detection in a reversed micellar medium formed by the cation surfactant cetyltrimethylammonium bromide in a dichloromethane-cyclohexane (3:7, v/v)-water (0.35 mol/L Na2CO3 buffer solution, pH 11.5). The ion-pair complex of tetrachloroaurate (III) with quinine sulphate produced an analytical CL signal when it entered the reversed micellar water pool. In optimum conditions, CL intensities are proportional to the concentrations of the studied drug over the range 0.015-10 microg/mL, with a detection limit of 1.5 ng/mL. The relative standard deviation (RSD) is 1.38% for 2.5 microg/mL quinine sulphate (n=11). The method has been applied to the determination of the studied drug in biological fluids, with satisfactory results.     

1α羟化酶活性和血钙水平对24羟化酶基因表达的影响

目的:研究肾脏24羟化酶基因表达的影响因素。方法:采用两种基因敲除小鼠。每种小鼠又分两种饲养方式。用生化分析仪测定小鼠血钙浓度。用半定量RT-PCR法研究小鼠肾脏组织中1α羟化酶和24羟化酶基因的表达。结果:1α羟化酶基因敲除小鼠体内血钙低于野生型小鼠(78±10.4 mg/Lvs111±16.5 mg/L,P<0.05.),测不出24羟化酶基因表达。维生素D受体基因敲除小鼠有很高的1α羟化酶表达,小鼠血钙也显著低于野生型小鼠(68±9.8 mg/Lvs111±16.5 mg/L,P<0.05),测不出24羟化酶表达。但给予高乳糖饲料后,两种基因敲除小鼠血钙都上升到与野生型小鼠一致水平。此时,24羟化酶基因的表达与野生型也基本一致。结论:血钙是调节24羟化酶基因表达的直接因素,1α羟化酶对24羟化酶的正向调节作用是通过升高血钙来实现的。     

鸡肉源沙门氏菌对喹诺酮和氟喹诺酮类抗生素耐药状况及相关基因

【目的】研究分离于陕西、河南、四川和北京四省(市)鸡肉源沙门氏菌对喹诺酮和部分氟喹诺酮类抗生素的药敏性及相关耐药基因,更好地了解耐药性的产生和传播途径,确保食品安全。【方法】用琼脂稀释法测定沙门氏菌的药敏性,用PCR和基因序列测定法确定耐药沙门氏菌中与(氟)喹诺酮类抗生素耐药相关的喹诺酮类抗性决定区基因突变及质粒携带的耐药基因。【结果】390株沙门氏菌中,63.59%的菌株对萘啶酮酸产生抗性,21.28%、16.67%和14.62%的菌株分别对环丙沙星、左氧氟沙星和加替沙星产生抗性。248株萘啶酮酸抗性菌中,aac(6’)-Ib-cr、qnrA、qnrB和qnrS基因的检出率分别为20.16%、10.89%、10.08%和1.61%。83株耐环丙沙星的菌株中,gyrA和parC基因的点突变共199个;其中gyrA基因中以Ser83Phe和Asp87Gly双突变最为常见,其次分别为Ser83Phe和Asp87Asn双突变、Ser83Tyr、Ser83Phe、Asp87Gly;parC基因的65个点突变均为Ser80Arg突变。【结论】四省市中鸡肉源沙门氏菌耐药状况严重,其解旋酶和拓扑异构酶基因突变及质粒携带的耐药基因是导致沙门氏菌耐药的重要机制。     

Comparison of the effects of symmetric and asymmetric temperature elevation and CO2 enrichment on yield and evapotranspiration of winter wheat (Triticum aestivum L.)

Under the changing climate, asymmetric warming pattern would be more likely during day and night time, instead of symmetric one. Concurrently, the growth responses and water use of plants may be different compared with those estimated based on symmetric warming. In this work, it was compared with the effects of symmetric (ETs) and asymmetric (ETa) elevation of temperature alone, and in interaction with elevated carbon dioxide concentration (EC), on the grain yield (GY) and evapotranspiration in winter wheat (Triticum aestivum L.) based on pot experiment in the North China Plain (NCP). The experiment was carried out in six enclosed‐top chambers with following climate treatments: (1) ambient temperature and ambient CO₂ (CON), (2) ambient temperature and elevated CO₂ (EC), (3) elevated temperature and ambient CO₂ (ETs; ETa), and (4) elevated temperature and elevated CO₂ (ECETs, ECETa). In symmetric warming, temperature was increased by 3°C and in asymmetric one by 3.5°C during night and 2.5°C during daytime, respectively. As a result, GY was in ETa and ETs 15.6 (P < 0.05) and 10.3% (P < 0.05) lower than that in CON. In ECETs and ECETa treatments, GY was 14.9 (P < 0.05) and 9.1% (P < 0.05) higher than that in CON. Opposite to GY, evapotranspiration was 7.8 (P < 0.05) and 17.9% (P < 0.05) higher in ETa and ETs treatments and 7.2 (P < 0.05) and 2.1% (P > 0.05) lower in ECETs and ECETa treatments compared with CON. Thus, GY of wheat could be expected to increase under the changing climate with concurrent elevation of CO₂ and temperature as a result of increased WUE under the elevated CO₂. However, the gain would be lower under ETa than that estimated based on ETs due to higher evapotranspiration.     

水稻OsMS2基因在花药发育中的功能分析

拟南芥MS2(MALE STERILITY 2)是一个调控花药花粉发育的关键基因。水稻OsMS2(Os03g07140)基因与拟南芥MS2的序列具有高度同源性。利用RNA干扰技术研究OsMS2基因在水稻花药发育过程中的功能。与野生型水稻相比, 转基因 植株营养生长阶段正常, 但雄性育性降低。转基因植株雄性育性降低与RNA干扰引起的OsMS2基因表达水平降低有关。进一步对转基因植株花药进行细胞学观察, 结果表明OsMS2基因表达水平的降低导致绒毡层细胞退化延迟, 小孢子壁的形成出现异常。扫描电镜观察结果显示, 小孢子壁光滑, 不能形成正常的外壁。以上结果表明OsMS2基因在水稻花药发育过程中起重要作用。     

Genome-wide regulation of 5hmC, 5mC, and gene expression by Tet1 hydroxylase in mouse embryonic stem cells

DNA methylation at the 5 position of cytosine (5mC) in the mammalian genome is a key epigenetic event critical for various cellular processes. The ten-eleven translocation (Tet) family of 5mC-hydroxylases, which convert 5mC to 5-hydroxymethylcytosine (5hmC), offers a way for dynamic regulation of DNA methylation. Here we report that Tet1 binds to unmodified C or 5mC- or 5hmC-modified CpG-rich DNA through its CXXC domain. Genome-wide mapping of Tet1 and 5hmC reveals mechanisms by which Tet1 controls 5hmC and 5mC levels in mouse embryonic stem cells (mESCs). We also uncover a comprehensive gene network influenced by Tet1. Collectively, our data suggest that Tet1 controls DNA methylation both by binding to CpG-rich regions to prevent unwanted DNA methyltransferase activity, and by converting 5mC to 5hmC through hydroxylase activity. This Tet1-mediated antagonism of CpG methylation imparts differential maintenance of DNA methylation status at Tet1 targets, ultimately contributing to mESC differentiation and the onset of embryonic development.     

猕猴属五个种mtDNA多态性研究

本文以10种限制性内切酶研究猕猴属5个种(Macaca mulatta.M.nemestrina.M.assemensis.M.thibetana,M arctoides)线粒体DNA进化。在13个个体中,共检出8种限制性类型。恒河猴种内存在广泛的线粒休DNA限制性片段长度多态性(RFLP)。结合日本猴(M.fuscata)的有关资料,构建了猕猴属6个种的分子系统树,并给出各个种的分化时间。结果表明,这6个种可分成4个类群,熊猴和藏酋猴、恒河猴和日本猴之间的遗传距离较近,可分别划为同一类群,红面猴与其他5种猴的遗传距离最远,在系统发生上分离最早。     

Litter species traits, but not richness, contribute to carbon and nitrogen dynamics in an alpine meadow on the Tibetan Plateau

Aims

Litter, as afterlife of plants, plays an important role in driving belowground decomposition processes. Here we tested effects of litter species identity and diversity on carbon (C) and nitrogen (N) dynamics during litter decomposition in N-limited alpine meadow soil from the Qinghai–Tibet Plateau.

Methods

We incubated litters of four meadow species, a sedge (“S”, Kobresia humilis), a grass (“G”, Elymus nutans), a herb (“H”, Saussurea superba), and a legume (“L”, Oxytropis falcata), in monoculture and in mixture with meadow soil. CO₂ release was measured 21 times during the incubation, and soil available N and microbial biomass C and N were measured before and after the experiment.

Results

The organic C decay rate did not differ much among soils amended with monocultures or mixtures of litter, except in the H, S, L, and S+H treatments, which had much higher decay rates. Potential decomposable C pools were lowest in the control, highest in the L treatment, and intermediate in the S treatment. Mineralized N was completely immobilized by soil microbes in all treatments except the control, S+L, and S+G+L treatments. Litter mixtures had both additive and non-additive effects on CO₂-C emission (mainly antagonistic effects), net N mineralization (mainly synergistic), and microbial biomass C and N (both). Overall, these parameters were not significantly correlated with litter species richness. Similarly, microbial C or N was not significantly correlated with litter N content or C/N. However, cumulative CO₂-C emission and net N mineralization were positively correlated with litter N content and negatively correlated with litter C/N.

Conclusions

Litter N content and C/N rather than litter species richness drove the release of CO₂-C and net available N in this ecosystem. The antagonistic effects of litter mixtures contributed to a modest release of CO₂-C, but their synergistic effects enhanced net available N. We suggest that in alpine meadow communities, balancing species with high and low N contents will benefit soil carbon sequestration and plant competition for available N with soil microbes.