浙江天童国家森林公园微地形与植被结构的关系

植物群落的本质特征之一是群落中的植物和环境之间存在一定的相互关系。丘陵地区的地形由各种微地形单元构成,这些微地形单元在空间上的分化提供的异质化的生境导致了区域丰富的物种和群落多样性的形成。选择浙江东部低山丘陵地区具有典型代表意义的天童国家森林公园,在地形识别的基础上,结合详细的植被调查,分析了不同微地形单元物种组成及其林分结构的变化。结果表明,基于物种组成相似性,7个微地形单元可以归为2组,与通过侵蚀前线划分结果一致。依据物种在这2个小尺度地形单元的分布格局,可以划分出3个特征种组,即上部坡面分布型、下部坡面分布型和无统计偏差型。壳斗科、山茶科、冬青科和山矾科常绿物种是构成上部坡面植被的主要成分,而榆科、槭树科、胡桃科和漆树科等的落叶种及樟科常绿种则是构成下部坡面植被的主要成分。下部坡面各微地形单元的林分垂直构造比上部坡面复杂,由榆科、槭树科、胡桃科和漆树科生境先锋种形成的明显超高层以及超大个体的存在是其显著特征。但其密度低于上部坡面微地形单元。上部坡面的顶坡和谷头凹地明显缺乏乔木层的存在。侵蚀前线是丘陵地区不同生境最重要的划分界限,由其切分的上部坡面和下部坡面是评价物种组成和林分结构的两大基本功能区域。     

酿酒酵母芳樟醇耐受性的工程改造

【背景】芳樟醇具有特殊的香气和多种生物学活性,是食品、医药和化妆品行业的重要原料。随着合成生物学的高速发展,代谢改造微生物进行芳樟醇生物合成是当前研究的一大热点。然而在微生物的生物合成中,芳樟醇对底盘细胞的毒性是一大瓶颈问题,也是其他单萜物质生物合成的共性问题。【目的】建立合理的耐受性改造方法,以提高微生物宿主细胞对芳樟醇的耐受性。【方法】以酿酒酵母BY4741为研究对象,通过对ABC转运蛋白、活性氧调控相关酶及转录调控因子的过表达,考察它们对酿酒酵母芳樟醇耐受性的影响,并通过对酿酒酵母细胞进行定向驯化,筛选耐受性提高的酿酒酵母突变株。【结果】单独过表达ABC转运蛋白(Yor1、Snq2、Pdr5、Pdr15和Pdr18)、ROS调控相关酶(Gre2、Ctt1、Yhb1、Gpx2、Trr1、Trx2和Gsh2)及转录调控因子(Ino2、Yap1、Yap5和Stb5)并不能有效提高酿酒酵母的耐受性,但在传代适应性驯化过程中获得了两株耐受性提高的酿酒酵母突变株,将芳樟醇的致死浓度从430mg/L提高到了645mg/L以上。进一步通过基因组重测序分析揭示了驯化菌株突变位点。其中YBR074W...     

Effects of MEK inhibitor U0126 on meiotic progression in mouse oocytes： microtuble organization, asymmetric division and metaphase Ⅱ arrest

In this study we used U0126, a potent and specific inhibitor of MEK, to study the roles of MEK/ERK/p90~(rsk) signaling pathway in the meiotic cell cycle of mouse oocytes. The phosphorylation of MAP kinase and p90~(rsk) in the oocytes treated with 1.5 μM U0126 was the same as that in oocytes cultured in drug-free medium. With 1.5 μM U0126 treatment, the spindles appeared normal as they formed in oocytes, but failed to maintain its structure. Instead, the spindle lost one pole or elongated extraordinarily. After further culture, some oocytes extruded gigantic polar bodies (>30 μm) that later divided into two small ones. Some oocytes underwent symmetric division and produced two equal-size daughter cells in which normal spindles formed. In oocytes with different division patterns, MAP kinase was normally phosphorylated. When the concentration of U0126 was increased to 15 mM, the phosphorylation of both MAPK and p90~(rsk) were inhibited, while symmetric division was decreased. When incubating in medium c     

凝血酶调节蛋白基因防治血管内膜增生狭窄的实验研究

目的:观察凝血酶调节蛋白(Thrombomodulin,TM)基因转染兔髂动脉损伤模型后,对动脉血管内膜增生狭窄的防治作用。方法:用注射式加压转染的方式对兔动脉壁转染pcDNA3.1/hTM质粒,再制造动脉损伤-阻滞模型,于术后3天、7天、14天、28天用免疫组化的方法观察TM蛋白在各组血管腔内的表达,术后14天、28天用彩色多普勒观察活体吻合口内径和血流流速;再做病理切片Verhoeff染色,观察血管内膜增生的程度、部位,计算血管内膜面积、中膜面积和血管狭窄率。结果:术后3天、7天、14天、28天hTM质粒转染组中hTM表达一直保持在高水平,7天达到高峰,14天、28天虽有所下降但是表达强度仍然高于载体质粒转染组合空白对照组。在术后14天、28天彩色多普勒观察测量吻合口内径:hTM质粒转染组分别为1.93mm±0.34mm,1.89mm±0.28mm;载体质粒转染组为1.59mm±0.43mm,1.38mm±0.28mm;空白对照组1.46mm±0.25mm,1.44mm±0.32mm。在这两个时间点,hTM质粒转染组血管狭窄率为32±23%,37±14%;载体质粒转染组为58±21%,63±17%;空白对照组为58±19%,61±23%。结论:hTM基因在转染动脉壁后能减少动脉损伤-阻滞模型在后期的血管内膜增生,改善血管的狭窄状况。     

Development and characterization of microsatellite loci from Olea europaea

This study reports 19 simple sequence repeat loci developed from a genomic library of the olive tree (Olea europaea L.), of which 12 revealed to be polymorphic and informative, ranging from two to 14 alleles.     

MYGALOMORPH SPIDERS (ARANEAE: DIPLURIDAE) FROM THE LOWER CRETACEOUS CRATO LAGERSTÄTTE, ARARIPE BASIN, NORTH-EAST BRAZIL

Abstract:  The first mygalomorph spiders from the Lower Cretaceous Crato Lagerstätte of Cearà Province, north-east Brazil, are described, from adult males and females, in two new genera and species: Cretadiplura ceara Selden, gen. et sp. nov. and Dinodiplura ambulacra Selden, gen. et sp. nov. They belong to the extant family Dipluridae, hitherto known as fossils only from Tertiary strata; thus this occurrence extends the family record by some 90 myr.     

Triggers of phytoplankton bloom dynamics in permanently eutrophic waters of a South African estuary

The permanently eutrophic Sundays Estuary experiences recurrent harmful algal blooms (HABs) of Heterosigma akashiwo (Raphidophyceae). This study aimed to identify the environmental variables shaping phytoplankton community composition and succession patterns during a typical spring/summer harmful algal bloom (HAB) period. Monitoring of abiotic and phytoplankton variables was undertaken over the period of a month in 2016. Surface water salinity corresponding to mesohaline conditions (9 to 12) was a prerequisite for site selection. During the study, two HABs (>550 µg Chl a l^?1) of H. akashiwo occurred, each lasting for approximately a week in duration. Analyses highlighted nutrient depletion (i.e. nitrate and phosphate concentrations) as the key constraint on bloom duration. When the density of H. akashiwo decreased, the community composition became more diverse with species belonging to Bacillariophyceae and Dinophyceae becoming more abundant; albeit to a lesser degree (<180 µg Chl a l^?1). Dissolved oxygen shifted from super-saturated conditions (>14 mg l^?1) during peak HAB conditions, to instances of bottom water oxygen depletion (2–4 mg l^?1) during the decay phase. These findings highlight the potential severity of transforming a catchment from natural to one that is highly regulated by agricultural practices, while also emphasising the need for management intervention.