泛素化修饰与植物免疫应答

植物暴露在细菌、病毒和真菌等病原微生物环境中,病虫害是限制农作物产量和品质的主要因素,而植物病虫害的防治依赖于对植物抗病机制的深入认识。近年来的研究表明,蛋白质泛素化广泛地参与植物防御调节。蛋白质泛素化是真核生物中重要的翻译后修饰方式之一,在植物中,泛素化修饰在多种信号传导途径中发挥作用,如激素、光、糖应答,发育调节和病原菌防御信号途径等。综述了蛋白质泛素化修饰在植物免疫应答中的调控作用。     

瓜子金化学成分的研究

自瓜子金(Palygala japonica)中分离出16个化合物,本文报道其中4个化台物的分离和结构鉴定。经化学和光谱解析,鉴定为β-谷甾醇(1)、β-胡萝卜甙(Ⅱ)、槲皮素(Ⅲ)和鼠李亭-3-O-葡萄吡喃糖甙(Ⅳ),均为首次从该植物中获得。     

Retracted: Tusk shells in trouble? Physiology and behavior in response to changing temperature in a scaphopod (Mollusca: Scaphopoda: Dentaliida)

Scaphopods (tusk shells) are infaunal marine predators that occur at locally high densities in coastal and deep‐sea mud habitats, and as consumers of foraminifera they are important in carbon cycling. We investigated oxygen metabolism and burying behavior of the scaphopod Rhabdus rectius and its responses to altered temperatures. These are the first measurements of oxygen uptake rates for any member of this taxonomic class. In response to elevated temperatures, oxygen uptake rates increased, but the ability of animals to bury themselves in sediment was compromised. Female scaphopods were significantly larger than males and, when corrected for body mass, oxygen uptake rates were consistently higher for female individuals than for males. This is consistent with previous anecdotal observations of females in other scaphopod species being larger and potentially more active. In conditions of declining oxygen availability, individuals of Rhabdus rectius showed strong oxyregulatory ability by maintaining the same oxygen uptake rate displayed in normoxic conditions. The ability to maintain normal metabolic functioning even in conditions of oxygen limitation would benefit a species living in a benthic environment that may be prone to temporary or transient anoxic events. Yet the decrease in normal escape response in moderately elevated temperatures indicates these animals may be at risk from rising sea temperatures.     

Signs of stabilisation and stable coexistence

Many empirical studies motivated by an interest in stable coexistence have quantified negative density dependence, negative frequency dependence, or negative plant–soil feedback, but the links between these empirical results and ecological theory are not straightforward. Here, we relate these analyses to theoretical conditions for stabilisation and stable coexistence in classical competition models. By stabilisation, we mean an excess of intraspecific competition relative to interspecific competition that inherently slows or even prevents competitive exclusion. We show that most, though not all, tests demonstrating negative density dependence, negative frequency dependence, and negative plant–soil feedback constitute sufficient conditions for stabilisation of two‐species interactions if applied to data for per capita population growth rates of pairs of species, but none are necessary or sufficient conditions for stable coexistence of two species. Potential inferences are even more limited when communities involve more than two species, and when performance is measured at a single life stage or vital rate. We then discuss two approaches that enable stronger tests for stable coexistence‐invasibility experiments and model parameterisation. The model parameterisation approach can be applied to typical density‐dependence, frequency‐dependence, and plant–soil feedback data sets, and generally enables better links with mechanisms and greater insights, as demonstrated by recent studies.     

湖北斧头湖湖滨湿地植物的联结与相关分析

利用２×２列联表法结合Ｘ２检验对湖北武昌斧头湖湖滨湿地植物进行了联结分析,计算了种间的相关系数并检验了种间相关显著性。结果表明这些种组构成了一个连续体。文中还讨论了各种组的生态意义。     

Mechanisms of the acute ischemia-induced arrhythmogenesis--a simulation study

The underlying ionic mechanisms of ischemic-induced arrhythmia were studied by the computer simulation method. To approximate the real situation, ischemic cells were simulated by considering the three major component conditions of acute ischemia (elevated extracellular K(+) concentration, acidosis and anoxia) at the level of ionic currents and ionic concentrations, and a round ischemic zone was introduced into a homogeneous healthy sheet to avoid sharp angle of the ischemic tissue. The constructed models were solved using the operator splitting and adaptive time step methods, and the perturbation finite difference (PFD) scheme was first used to integrate the partial differential equations (PDEs) in the model. The numerical experiments showed that the action potential durations (APDs) of ischemic cells did not exhibited rate adaptation characteristic, resulting in flattening of the APD restitution curve. With reduction of sodium channel availability and long recovery of excitability, refractory period of the ischemic tissue was significantly prolonged, and could no longer be considered as same as APD. Slope of the conduction velocity (CV) restitution curve increased both in normal and ischemic region when pacing cycle length (PCL) was short, and refractory period dispersion increased with shortening of PCL as well. Therefore, dynamic changes of CV and dispersion of refractory period rather than APD were suggested to be the fundamental mechanisms of arrhythmia in regional ischemic myocardium.     

Involvement of Matrix Metalloproteinases on the Inhibition of Cells Invasion and Migration by Emodin in Human Neuroblastoma SH-SY5Y Cells

Emodin (1,3,8-trihydroxy-6-methylanthaquinone), an active component present in the root and rhizome of Rheum palmatum L. (Polygonaceae) has anti-bacterial, anti-tumor, diuretic and vasorelaxant effects. However, its mechanism of action on the cell migration and invasion of human neuroblastoma cancer SH-SY5Y cells is not fully understood. In this study, firstly, the effects of emodin on the percentage of viable cells were examined by using MTT assay and it was found that emodin induced dose-and time-dependent inhibition in human neuroblastoma SH-SY5Y cells. Second, the effects of emodin on the migration and invasion of SH-SY5Y cells were examined by using wound assay and matrigel counting and the results showed that emodin suppressed the migration and invasion of SH-SY5Y cells. Third, we examined the effect of emodin on the levels of associated proteins by using Western blotting and the results indicated that emodin inhibited the levels of GRB2, RhoA, HIF-1α, VEGF, FAK, iNOS, COX2, p-p38, p-c-jun, MMP2, MMP9 and MMP7 but promoted the levels of PKC, PI3K, MEKK3 and NF-κB p65 that led to the inhibition of migration and invasion of SH-SY5Y cells in vitro.     

一次陆源降雨污水引起血红哈卡藻赤潮的成因

以2007年烟台四十里湾海域血红哈卡藻(Akashiwo sanguinea Hirasaka)赤潮为对象,研究赤潮消长与水环境因子的关系。研究发现大量陆源降雨污水输入后,海水盐度急剧下降、营养盐大幅增加,特别是活性磷酸盐浓度明显增加,促进了血红哈卡藻的生长繁殖并最终形成赤潮。赤潮发生前海区第一优势种为尖刺拟菱形藻(Pseudo-nitzschia pungens Halse),优势度0.47(0.42—0.52),多样性指数2.63(2.43—2.89);赤潮发生时血红哈卡藻密度范围1.05×105—4.10×106个/L,优势度0.92(0.83—0.99),多样性指数0.27(0.15—0.64);赤潮消退后中肋骨条藻(Skeletonema costatum Cleve)为第一优势种,优势度0.49(0.43—0.55),多样性指数2.46(2.19—2.84)。赤潮的发生、发展、消亡与化学需氧量(COD)、无机氮(DIN)、活性磷酸盐(DIP)、富营养化指数(E)呈显著正相关(P<0.05),与盐度呈显著负相关(P<0.01)。赤潮前、后该海域为贫营养、P限制、叶绿素a含量中等,赤潮期间该海域为富营养、P限制、叶绿素a含量高。通过影响力评定,活性磷酸盐、COD、盐度是此次赤潮发生的主要诱发因子,当活性磷酸盐含量低于0.3μmol/L时,硅藻逐渐取代甲藻,此次赤潮消散。     

水圈微生物专栏序言

<正>国家自然科学基金委员会于2017年启动了“水圈微生物驱动地球元素循环的机制”重大研究计划(简称“水圈微生物”计划)。“水圈微生物”计划聚焦典型水圈生境,通过多学科交叉研究,借助新技术、新方法,揭示水圈微生物在物种、群落和生态水平驱动碳氮硫循环的机制及其环境响应,认识水圈微生物在元素地球生物化学循环中的宏观生态作用,为应对全球变化、保护水圈生态服务功能、实施双碳战略、