Fine‐scale habitat heterogeneity explains the local distribution of two Amazonian frog species of concern for conservation

To test the hypothesis that subtle differences in abiotic requirements can result in almost total spatial segregation, we sampled two species of diurnal frogs, Atelopus spumarius and Allobates sumtuosus, in a primary forest reserve in central Brazilian Amazonia. We conducted visual and acoustic surveys on three occasions over 2 months, in 40 streamside (riparian) plots distributed throughout the reserve's two major drainage basins, using a grid system that covers 64 km². On average, drainages differed in the pH of stream water and the number of connected and isolated streamside pools. Differences in abiotic characteristics of drainages were associated with the spatial distribution of frog species. The occurrence and density of Allobates sumtuosus was negatively related to stream pH and discharge and positively related to the number of isolated pools in plots. The occurrence and density of Atelopus spumarius was associated with streams with high discharge and pH near neutral. These results indicate that although very large reserves will probably contain sufficient landscape heterogeneity to accommodate different species of diurnal frogs, due to strongly patchy distributions, in situ studies using fine‐scale species‐distribution models will be necessary to assess the adequacy of small reserves in Amazonia that cover hundreds of square kilometers or less for the conservation of some anuran species.     

Drought-induced dynamics of carbon and water use efficiency of global grasslands from 2000 to 2011

Drought is frequently recorded as a result of climate warming and elevated concentration of greenhouse gases, which affect the carbon and water cycles in terrestrial ecosystems, particularly in arid and semi-arid regions. To identify the drought in grassland ecosystems and to determine how such drought affects grassland ecosystems in terms of carbon and water cycles across the globe, this study evaluated the drought conditions of global grassland ecosystems from 2000 to 2011 on the basis of the remotely sensed Drought Severity Index (DSI) data. The temporal dynamics of grassland carbon use efficiency (CUE) and water use efficiency (WUE), as well as their correlations with DSI, were also investigated at the global scale. Results showed that 57.04% of grassland ecosystems experienced a dry trend over this period. In general, most grassland ecosystems in the northern hemisphere (N.H.) were in near normal condition, whereas those in the southern hemisphere (S.H.) experienced a clear drying and wetting trend, with the year 2005 regarded as the turning point. Grassland CUE increased continually despite the varied drought conditions over this period. By contrast, WUE increased in the closed shrublands and woody savannas but decreased in all the other grassland types. The drought conditions affected the carbon and water use mainly by influencing the primary production and evapotranspiration of grass through photosynthesis and transpiration process. The CUE and WUE of savannas was most sensitive to droughts among all the grassland types. The areas of grassland DSI that showed significant correlations with CUE and WUE were 52.92% and 22.11% of the total grassland areas, respectively. Overall, droughts sufficiently explained the dynamics of grassland CUE, especially in the S.H. In comparison with grassland CUE, the grassland WUE was less sensitive to drought conditions at the global scale.     

Stability study of Prulifloxacin and Ulifloxacin in human plasma by HPLC–DAD

A new and specific HPLC–DAD method for the direct determination of Prulifloxacin and its active metabolite, Ulifloxacin, in human plasma has been developed. Plasma samples were analysed after a simple solid phase extraction (SPE) clean-up using a new HILIC stationary phase based high-performance liquid chromatography (HPLC) column and an ammonium acetate buffer (5?mM, pH 5.8)/acetonitrile (both with 1% Et₃N, v/v) mobile phase in isocratic elution mode, with Danofloxacin as the internal standard. Detection was performed using DAD from 200 to 500?nm and quantitative analyses were carried out at 278?nm. The LOQ of the method was 1?μg/mL of the cited analytes and the calibration curve showed a good linearity up to 25?μg/mL. For both analytes the precision (RSD%) and the trueness (bias%) of the method fulfil with International Guidelines. The method was applied for stability studies, at three QC concentration levels, in human plasma samples stored at different temperature of?+?25,?+?4 and ?20?°C in order to evaluate plasma stability profiles.     

高产莫纳可林K低产桔霉素红曲霉菌株的筛选和发酵条件初步优化

采集全国各地红曲霉制品中的红曲霉资源,经分离获278株红曲霉菌株。高效液相色谱(HPLC)法测定各菌株发酵液中莫纳可林K(Monacolin K)和桔霉素含量,筛选获1株Monacolin K产量较高、桔霉素含量较低的红曲霉菌株编号为M-22。依据形态特征和ITS基因序列,参照红曲霉属分类检索表,鉴定M-22菌株为紫色红曲霉(Monascus purpureus)。通过摇瓶发酵对温度、初始pH、碳源、氮源、碳氮比(C/N)等因素进行优化,确定M-22菌株摇瓶发酵产Monacolin K适宜条件为发酵温度26℃、初始pH 5.0、转速160 r/min,甘油为碳源、蛋白胨为氮源、碳氮比(C/N)为5:1,Monacolin K产量显著提高,最高为107.16 mg/L。以优化的发酵条件对M-22菌株进行5 L发酵罐发酵,发酵液中Monacolin K产量最高为189.83 mg/L,桔霉素含量32.53μg/L,红曲色素色价为16.38 U/m L。     

The effect of nutrients and environmental conditions on biomass and oil production in Botryococcus braunii Race B strains

The green alga Botryococcus braunii is widely recognized as a source of non-fossil oil. However, limitations in Botryococcus biomass production hamper its commercial exploitation. This study examines the effects of nutrients (nitrogen and iron) and environmental conditions (temperature, light intensity and photoperiod) on biomass and oil production in two B. braunii Race B strains, Kossou-4 and Overjuyo-3. The highest biomass and oil production were obtained at a nitrogen concentration of 750 mg l^?1, iron concentration of 6 mg l^?1, at 25°C and at 135 µmol photons m^?2 s^?1 with a photoperiod of 16 h light:8 h darkness. Culturing the strains in Blue-green (BG11) medium containing optimized nutrients under optimal conditions resulted in an up to ~10.6-fold increase in biomass. In Kossou-4 and Overjuyo-3 strains, biomass increased from 1.647 g 10 l^?1 and 3.137 g 10 l^?1 respectively in normal BG11 medium to 17.390 g 10 l^?1 and 21.721 g 10 l^?1 in optimized BG11 media and growth conditions. This was accompanied by ~8–10.5-fold increase in oil production compared with that in normal BG11 medium. Oil (0.324 g 10 l^?1 and 0.211 g 10 l^?1) was produced in normal BG11 medium in Kossou-4 and Overjuyo-3 strains respectively, compared with 2.642 g 10 l^?1 (Kossou-4) and 2.206 g 10 l^?1 (Overjuyo-3) in modified BG11 media under optimized conditions. Therefore, optimization of nutrients and environmental conditions can increase biomass and oil production in the two strains of B. braunii.     

SC-CO2和乙酸乙酯萃取芸香中活性成分的比较分析

为了探讨超临界二氧化碳(supercritical carbon dioxide, SC-CO2)技术与提取物的分级分离在萃取芸香活性成分的应用价值,本研究采用SC-CO2和乙酸乙酯萃取芸香中植物蜡和活性成分,并调查粒径和CO2流量对提取产量的影响。在250 bar、40℃条件下提取,并使第一个分离器冷却到-10℃,可获得较好的提取效率。当粒径较小时,提取过程更快,即内部传质控制该过程。分级分离可选择性去除表皮植物蜡,约占由SC-CO2处理产生的总提取物的77.5%W/W。第二分离器中的获得的提取物中活性化合物可达86.3%W/W。随后采用气相色谱-质谱联用仪(gas chromatography-mass spectrometry, GC-MS)分析表明,乙酸乙酯提取物低于SC-CO2提取物的萃取效率,主要是由于提取物中含有大量的植物蜡。本研究为超临界二氧化碳技术在萃取芸香活性成分方面的提供技术参考。     

粘性丝孢酵母的诱变及以玉米秸秆水解液为原料产油条件优化

对粘性丝胞酵母进行紫外诱变,获得一株产油率较高的菌株,较原菌株提高了1.53倍。将该菌株接种于用1%硫酸和酶水解处理并浓缩至还原糖浓度为5%的玉米秸秆水解液中培养,生长较好。通过四因素三水平正交实验,确定培养条件为初始pH值7.0、接种量1%、发酵温度30℃、发酵时间5 d时产油率最高。对最佳产油条件进行验证,测得油脂含量为21.3%。从而为利用农业废弃物大规模生产微生物油脂提供了试验数据。气相色谱-质谱联用分析仪显示油脂脂肪酸组成为棕榈酸28.36%,油酸55.86%,10-十八烯酸9.23%,硬脂酸6.70%,可以作为原料生产生物柴油。     

三种车前草的黄酮提取、纯化及其抗氧化活性分析

本研究采用响应面设计优化超声辅助提取车前总黄酮的最佳条件,然后用此条件提取大车前和平车前总黄酮,并探究大孔树脂纯化对三种车前草总黄酮抗氧化活性的影响。结果表明,在超声温度60℃、乙醇浓度70%的条件下,车前总黄酮最佳提取工艺参数为液料比20:1 m L/g、超声时间80 min、超声功率210 W,车前、大车前和平车前的总黄酮得率分别为5.04%、2.86%和1.22%。无论是纯化前还是纯化后,大车前总黄酮的还原力和对羟基自由基的清除作用最强,平车前最弱;车前总黄酮对DPPH自由基的清除作用最大,平车前最弱。纯化前后的还原力和对DPPH自由基、羟基自由基的清除作用都接近Vc的水平。     

Individual variation in early‐life telomere length and survival in a wild mammal

Individual variation in survival probability due to differential responses to early‐life environmental conditions is important in the evolution of life histories and senescence. A biomarker allowing quantification of such individual variation, and which links early‐life environmental conditions with survival by providing a measure of conditions experienced, is telomere length. Here, we examined telomere dynamics among 24 cohorts of European badgers (Meles meles). We found a complex cross‐sectional relationship between telomere length and age, with no apparent loss over the first 29 months, but with both decreases and increases in telomere length at older ages. Overall, we found low within‐individual consistency in telomere length across individual lifetimes. Importantly, we also observed increases in telomere length within individuals, which could not be explained by measurement error alone. We found no significant sex differences in telomere length, and provide evidence that early‐life telomere length predicts lifespan. However, while early‐life telomere length predicted survival to adulthood (≥1 year old), early‐life telomere length did not predict adult survival probability. Furthermore, adult telomere length did not predict survival to the subsequent year. These results show that the relationship between early‐life telomere length and lifespan was driven by conditions in early‐life, where early‐life telomere length varied strongly among cohorts. Our data provide evidence for associations between early‐life telomere length and individual life history, and highlight the dynamics of telomere length across individual lifetimes due to individuals experiencing different early‐life environments.