酵母不对称催化制备R-1,2-丙二醇

研究了采用面包酵母还原丙酮醇制备R-1,2-丙二醇的工艺。采用摇瓶对转化条件进行单因素实验,确定最优转化条件：丙酮醇浓度0.3mmol/mL,pH7.0,酵母质量浓度150g/L,乙醇浓度为0.3mmol/mL,转化时间25h。在此条件下,采用分批流加策略进行1.5L规模发酵罐转化试验,转化25h后,发酵液的R-1,2-丙二醇浓度为0.27mmol/mL。     

泡菜中优良乳酸菌的分离、鉴定及发酵特性

从几种泡菜中分离出86株菌,对其在适温和低温下产酸速率及硝酸盐降解能力进行测定,筛选出5株产酸速率快、硝酸盐降解能力强的菌株。经形态学鉴定及生理生化反应试验,初步鉴定为：植物乳杆菌2株,短乳杆菌1株,戊糖乳杆菌1株,肠膜明串珠菌葡聚糖亚种1株,并对5株菌的发酵性能进行了测定。     

虫药蜣螂对灵芝发酵物风味组成的影响

采用顶空-气相色谱-质谱联用对虫药蜣螂和添加蜣螂发酵后的灵芝发酵物的风味物质进行了测定,进而分析了添加蜣螂对灵芝发酵物风味组成的影响。结果表明,虫药蜣螂和灵芝发酵物(添加蜣螂)中分别含有40和30多种风味物质。添加蜣螂发酵后,灵芝发酵物跟对照相比新出现了5种风味物质,分别为苯甲醛、α-松油醇、苯乙醇、唑苯并噻和桃金娘烯醇。其中α-松油醇、苯乙醇和唑苯并噻是蜣螂中的风味成分,苯甲醛和桃金娘烯醇为新产生成分。所有5种风味物质均为食品香料物质。蜣螂中其它风味成分经灵芝发酵转化或降解后,未出现在灵芝发酵物中。因此,添加蜣螂发酵对灵芝发酵物的风味无不良影响。结果还提示灵芝细胞可生物转化或降解虫药蜣螂中的部分风味物质。     

高效液相色谱法同时测定儿童血清中视黄醇、25-OH-维生素D3和α-生育酚浓度

目的:建立能同时测定儿童血清中视黄醇、25-OH-维生素D3和a-生育酚的高效液相色谱(high performance liquid chromatography,HPLC)法.方法:以无水乙醇沉淀蛋白质后,血清中的脂溶性维生素用正己烷提取,吹氮气浓缩后用HPLC测定.结果:视黄醇、25-OH-维生素D3和a-生育酚的线性范围分别为0.015-500μg/mL、0.012-500μg/mL和0.1-500 μg/mL;检出限分别为0.015μg/mL、0.012μg/mL和0.1μg/mL;相对标准偏差分别为0.98%、2.09%和4.63%.三种脂溶性维生素各个浓度的提取回收率均大于80%,方法回收率均大于90%.结论:本法简便快速,适于血清样品中视黄醇、25-OH-维生素D3和a-生育酚三种脂溶性维生素的同时测定.     

转基因果蝇模型与多聚谷氨酰胺疾病

多聚谷氨酰胺(polyglutamine,PolyQ)疾病是由CAG三核苷酸异常重复扩增并编码多聚谷氨酰胺链而致病的一类疾病.目前,已经发现了9种PolyQ疾病,临床表现为成年起病,缓慢进展性的神经系统功能障碍.近年来许多研究者用转基因动物模型(小鼠、果蝇、斑马鱼等)研究神经退行性疾病的表型、发病机制及治疗,其中,果蝇以其独特的分子遗传学优势成为研究PolyQ疾病的理想模式生物.本文就运用转基因果蝇研究PolyQ疾病的表型及发病机制作一综述.     

门静脉高压症大鼠肠系膜组织内皮素B受体表达的变化

目的:探讨胆汁性肝纤维化引起的门静脉高压症(PHT)大鼠肠系膜组织内皮素B受体表达(ETBR)的变化.方法:取体重250±10 g左右的清洁级SD雄性大鼠30只,根据体重随机分为假手术组、模型组,模型制作采用胆总管结扎的方法造成大鼠胆汁性肝纤维化.术后2周和4周分别测定各组的门静脉压力,应用免疫组化和免疫印迹的方法观察肠系膜组织ETBR的表达.结果:术后2周和4周模型组门静脉压力显著升高,分别为11.89±1.38 mmHg和16.34±1.63 mmHg.免疫组化显示假手术组肠系膜组织ETBR主要见于细动脉内皮细胞,而模型组大鼠ETBR的表达不仅见于细动脉内皮细胞,细动脉平滑肌细胞和微动脉表达也很显著.免疫印迹发现假手术组肠系膜组织ETBR含量很少,模型组大鼠ETBR表达明显增多.结论:正常大鼠肠系膜血管组织ETBR表达较少,随着肝组织损伤加剧和PHT形成,肠系膜组织ETBR表达明显增加,可能参与胆汁性肝硬化PHT形成过程.     

高危型HPV-DNA检测对宫颈病变的诊断价值

目的:评价高危型人类乳头瘤病毒(high-risk human papilloma virus,HR-HPV)DNA检测对宫颈病变的诊断价值.方法:对门诊450例细胞学异常的患者,采用杂交捕获试验法(Hybrid Capture Ⅱ,HCⅡ)检测HR-HPV-DNA,并行阴道镜检查.结果:细胞学诊断中非典型鳞状细胞332例,低度鳞状上皮内病变87例,高度鳞状上皮内病变31例,HPV-DNA阳性率分别为30.7%(102/332),44.8%(39/87),90.3%(28/31);病理学诊断中无上皮内病变或恶性病变、子宫颈上皮瘤(cervical intra-qaithelial neoplasia,CIN)Ⅰ/Ⅱ、CIN Ⅲ和原位癌HPV-DNA阳性率分别为31.2%(73/219)、47.3%(96/203)、100%(28/28),随细胞学检查的级别增高,HPV-DNA高危型阳性率增加(P＜0.05).结论:高危型HPV-DNA检测是宫颈癌筛查的有效方法,建议临床推广应用.     

广州市昆虫群落结构及动态

2005-2006年对广州市全区域的昆虫群落进行6次调查,对该区域昆虫群落结构、多样性及时间动态进行了分析.共记述22个目、216个科.鞘翅目的类群最丰富,双翅目、鳞翅目、膜翅目和半翅目次之;鞘翅目昆虫的个体数量最多(30.45),其次为鳞翅目(18.89)和膜翅目(14.78).6～7月昆虫类群数和个体数量最多,12月最少;6～7月的种类丰度最高,其次为3～4月、9～10月,12月最低;Shannon-Wiener指数从高到低依次为6～7月、9～10月、3～4月、12月;Pielou均匀度指数从高到低依次为6～7月、9～10月、12月、3～4月;12月的种类优势度最高,其次为3～4月、9～10月,最低为6～7月.     

Increased temperature and precipitation interact to affect root production,mortality, and turnover in a temperate steppe: implications for ecosystem C cycling

Fine root production and turnover play important roles in regulating carbon (C) cycling in terrestrial ecosystems. In order to examine effects of climate change on root production and turnover, a field experiment with increased temperature and precipitation had been conducted in a semiarid temperate steppe in northern China since April 2005. Experimental warming decreased annual root production, mortality, and mean standing crop by 10.3%, 12.1%, 7.0%, respectively, while root turnover was not affected in 2006 and 2007 by the warming. Annual root production and turnover was 5.9% and 10.3% greater in the elevated than ambient precipitation plots. Changes in root production and mortality in response to increased temperature and precipitation could be largely attributed to the changes in gross ecosystem productivity (GEP) and belowground/aboveground C allocation. There were significant interactive effects of warming and increased precipitation on root productivity, mortality, and standing crop. Experimental warming had positive and negative effects on the three root variables (root production, mortality, standing crop) under ambient and increased precipitation, respectively. Increased precipitation stimulated and suppressed the three root variables in the unwarmed and warmed subplots, respectively. The positive dependence of soil respiration and ecosystem respiration upon root productivity and mortality highlights the important role of root dynamics in ecosystem C cycling. The nonadditive effects of increased temperature and precipitation on root productivity, mortality, and standing crop observed in this study are critical for model projections of climate–ecosystem feedbacks. These findings indicate that carbon allocation is a focal point for future research and that results from single factor experiments should be treated with caution because of factor interactions.     

Tradeoffs and thresholds in the effects of nitrogen addition on biodiversity and ecosystem functioning: evidence from inner Mongolia Grasslands

Nitrogen (N) deposition is widely considered an environmental problem that leads to biodiversity loss and reduced ecosystem resilience; but, N fertilization has also been used as a management tool for enhancing primary production and ground cover, thereby promoting the restoration of degraded lands. However, empirical evaluation of these contrasting impacts is lacking. We tested the dual effects of N enrichment on biodiversity and ecosystem functioning at different organizational levels (i.e., plant species, functional groups, and community) by adding N at 0, 1.75, 5.25, 10.5, 17.5, and 28.0 g N m^?2 yr^?1 for four years in two contrasting field sites in Inner Mongolia: an undisturbed mature grassland and a nearby degraded grassland of the same type. N addition had both quantitatively and qualitatively different effects on the two communities. In the mature community, N addition led to a large reduction in species richness, accompanied by increased dominance of early successional annuals and loss of perennial grasses and forbs at all N input rates. In the degraded community, however, N addition increased the productivity and dominance of perennial rhizomatous grasses, with only a slight reduction in species richness and no significant change in annual abundance. The mature grassland was much more sensitive to N‐induced changes in community structure, likely as a result of higher soil moisture accentuating limitation by N alone. Our findings suggest that the critical threshold for N‐induced species loss to mature Eurasian grasslands is below 1.75 g N m^?2 yr^?1, and that changes in aboveground biomass, species richness, and plant functional group composition to both mature and degraded ecosystems saturate at N addition rates of approximately 10.5 g N m^?2 yr^?1. This work highlights the tradeoffs that exist in assessing the total impact of N deposition on ecosystem function.