NaNO3胁迫对两种微囊藻VOCs释放的影响

为了揭示硝酸盐过量积累对藻类产生胁迫后对藻类挥发性有机化合物(VOCs)释放以及水体气味的影响, 研究以形成蓝藻水华的主要种类铜绿微囊藻和水华微囊藻为材料, 在NaNO3胁迫下, 对其细胞生长和释放的VOCs进行测定分析。结果表明, NaNO3胁迫24h后, 铜绿微囊藻和水华微囊藻细胞生长均受到明显影响, 与对照相比细胞密度分别降低了29.6%和43.0%。在正常条件下, 铜绿微囊藻和水华微囊藻分别释放出26和27种化合物, 其主要类型是硫化物、烃类、萜烯类、苯类、醛类和酯类化合物。在NaNO3胁迫下, VOCs含量均明显增加, 其中铜绿微囊藻释放的此6类VOCs含量分别增加了60.5%、14.3%、136.6%、92.1%、730.0%和120.7%, 水华微囊分别增加了172.7%、162.5%、154.0%、55.9%、51.2%和109.4%。此外, 铜绿微囊藻VOCs中出现4种新成分, 水华微囊藻VOCs中出现1种新成分。由此可见, 硝酸盐过量积累对藻细胞产生胁迫后会诱导其释放出大量VOCs, 从而增加水体气味、破坏水质。       

蓝藻挥发物α-紫罗酮诱导莱茵衣藻细胞程序性死亡

【目的】蓝藻挥发性有机化合物(VOCs)对其他藻类的化感作用可促进蓝藻成为富营养化水体优势种群,本研究旨在以VOCs主要成分α-紫罗酮为例揭示其化感致死机制。【方法】采用α-紫罗酮处理莱茵衣藻,测定藻细胞生长以及致死浓度下藻细胞光合性能、caspase-likes活性和DNA ladders。【结果】采用0.05和0.1mmol/Lα-紫罗酮处理24h后,莱茵衣藻细胞生长均受到明显抑制,其中0.1 mmol/L处理时部分藻细胞发生死亡,死亡率为38.3%。采用0.2 mmol/Lα-紫罗酮处理时,藻细胞全部死亡,同时光合色素逐渐降解、Fv/Fm逐渐降低并消失,这表明藻细胞死亡并非坏死。在藻细胞死亡过程中,caspase-9-like和caspase-3-like活性明显增强;DNA在处理1h时出现ladders,并逐渐降解为100–250 bp片段。【结论】这表明蓝藻VOCs可通过诱导细胞程序性死亡以发挥化感作用。     

环境汞污染对藻类的毒性效应及其影响因素

综述了汞污染对藻类的毒性效应及影响因素。水环境中汞主要以元素汞、无机汞和有机汞3种形式存在。藻类吸附汞主要分为胞外的快速吸附和胞内的缓慢富集,在安全浓度内,金属汞对藻生长有一定的促进作用,随着浓度增大,抑制藻生长或致死。汞进入藻体细胞后,藻类为了存活会产生一系列保护机制。藻类对汞的排斥和排出作用可能就是对汞耐性的一种重要机制。藻类也可以通过多种方式减少汞进入藻类细胞,以及通过与其他物质结合汞使其排出胞外。温度、pH、生物学因素等影响重金属对藻类的毒性作用。并就藻类对汞耐性和适应机理、利用藻类修复和监测重金属污染、藻类响应汞胁迫的信号转导途径及其保护机制等未来研究领域进行了展望。     

沉水植物化感作用控藻能力评述

沉水植物所释放的化学物质对藻类的抑制作用是浅水湖泊维持清水状态的机制之一.本文从具有化感活性的沉水植物在湖泊中出现的频度、盖度、化感物质的种类、抑藻效应等方面对化感控藻进行了评述.已有研究结果表明：穗花狐尾藻、金鱼藻、伊乐藻等是具有很高活性的沉水植物,尤其是在其生物量达到一定程度,且湖泊中的优势藻为较敏感的种类时,沉水植物分泌的化感物质对浮游藻类的抑制作用更强;沉水植物释放的多酚类等化感物质具有控藻能力;化感物质对于不同种类藻的抑制作用具有选择性,蓝藻和硅藻比绿藻更为敏感,附生藻类通常比浮游藻类具有更高的耐受性;环境因素如光照、营养限制、温度等会显著影响沉水植物化感作用效果.沉水植物的化感控藻研究尚处于初始阶段,关于环境因素对化感作用的影响、化感物质的分离鉴定、选择性抑藻机理以及化感物质代谢途径等方面还有待深入、全面的研究.     

植物间挥发物信号的研究进展

植物VOCs信号是植物间进行信息交流的“语言”, 可由多种生物和非生物因素诱导产生。非寄生植物释放的VOCs信号可影响其所在群落中其它植物的种子萌发与幼苗生长; 而寄主植物释放的VOCs信号却是诱导寄生植物种子萌发和幼苗生长的信号物质。VOCs作为植物间的伤害信息可以诱导临近的同种或异种植物做好防御准备, 从而通过主动或间接防御以减少外界的伤害。植物间通过VOCs信号进行信息交流, 从而实现其繁衍与防御。该文通过对VOCs信号的种类、诱导产生因素、传递及作用进行综述, 以期对VOCs信号的研究有所帮助。     

植物间挥发物信号的研究进展

植物VOCs信号是植物间进行信息交流的"语言",可由多种生物和非生物因素诱导产生。非寄生植物释放的VOCs信号可影响其所在群落中其它植物的种子萌发与幼苗生长;而寄主植物释放的VOCs信号却是诱导寄生植物种子萌发和幼苗生长的信号物质。VOCs作为植物间的伤害信息可以诱导临近的同种或异种植物做好防御准备,从而通过主动或间接防御以减少外界的伤害。植物间通过VOCs信号进行信息交流,从而实现其繁衍与防御。该文通过对VOCs信号的种类、诱导产生因素、传递及作用进行综述,以期对VOCs信号的研究有所帮助。     

藻类产生及清除过氧化氢的研究

过氧化氢的生物生成是天然水体中H2O2的来源之一。从藻类产生及分解过氧化氢的途径,影响过氧化氢产量的主要因素,如藻的种类、细胞的渗透性、藻的生长阶段、藻浓度和光照条件等几方面对这一领域的研究作了综述。     

微囊藻毒素缓解过氧化氢胁迫下铜绿微囊藻损伤的初步研究

过氧化氢可抑制藻类生长, 同时会导致微囊藻毒素(Microcystins, MCs)的释放, 实验设置4个处理组探讨了外源微囊藻毒素MC-LR对H2O2胁迫下铜绿微囊藻生理生化变化的影响。结果表明: 在H2O2胁迫下, 微囊藻的生长和光合活性受到显著抑制, 藻细胞存活率降低, ROS含量明显增加, SOD活性上升。与单独H2O2胁迫相比, 加入MC-LR能增加微囊藻细胞的存活率。250 mol/L H2O2处理24h和48h后, 在培养基中加入200 ng/mL MC-LR可以缓解H2O2对铜绿微囊藻光合系统PSII活性的抑制作用。当微囊藻暴露于250 mol/L H2O2环境中时, 添加了MC-LR处理组藻细胞中的ROS含量明显减少(P0.05)。在相同浓度H2O2且加入了外源MC-LR后藻细胞SOD活性下降(P0.05)。因此, 微囊藻毒素MC-LR可缓解250 mol/L H2O2引起的氧化损伤并增强微囊藻自身的生存能力。研究结果有利于阐明H2O2胁迫影响产毒蓝藻生长代谢的途径及MCs生物学意义。       

信号分子介导藻类细胞程序性死亡的研究进展

藻类是水生态系统中的重要初级生产者, 在物质转换和能量迁移过程中发挥重要作用。细胞程序性死亡(PCD)作为一种细胞自我调控的死亡模式, 受到多种信号分子的控制。研究发现藻类细胞在遭受环境胁迫的情况下, 在形态和生理上均表现出类PCD的特征, 同时伴随着活性氧/一氧化氮/钙离子(ROS/NO/Ca2+)水平的变化。研究认为, ROS/NO/Ca2+作为信号分子介导藻细胞内的caspase-like酶活性变化, 从而触发藻细胞的类程序性死亡。然而, 对信号分子是如何在环境胁迫下的藻类细胞中引发类PCD仍知之甚少。文章综述了信号分子ROS/NO/Ca2+介导藻类类PCD的研究进展以及信号分子间的级联关系, 并对今后类PCD在该领域待开展的研究进行了展望。     

海洋微藻响应重金属复合胁迫的生理生态学机制

重金属污染物进入海洋环境会破坏海洋生态系统的结构和功能。海洋微藻构成了海洋食物链的基础, 是海洋生态系统主要的初级生产者。重金属复合胁迫对海洋微藻产生毒性效应, 会阻碍藻细胞分裂、破坏DNA结构、抑制光合作用、减少细胞色素合成、导致藻细胞畸变以及改变浮游植物种类组成等。海洋微藻在长期种系进化或个体发育过程中, 形成了一系列响应重金属复合胁迫的特殊生理生态机制。它们可以利用由酶类和非酶类组成的抗逆保护系统, 减轻重金属复合胁迫导致的生物毒害作用; 还可以通过调节金属硫蛋白(Metallothionein, MT)等相关蛋白基因表达以维持正常的生理功能。探究海洋微藻响应重金属复合胁迫的生理生态学机制, 有利于为海洋重金属污染的生物修复提供依据, 具有重要的理论与现实意义。     

环境因子对植物释放挥发性化合物的影响

对近年来有关环境因子与植物释放挥发性化合物关系的研究进展进行了综合和概括。本文主要包括3类挥发性化合物。⑴异戊二烯是由叶绿体产生并且直接释放到大气中的C5化合物。⑵单萜类化合物是一类环状或非环状的C10化合物,它在植物体内合成后首先贮存于体内的特殊结构中（如树脂道、油腺）,然后由此通过气孔向大气中释放。⑶含氧挥发性化合物以各种形式释放大大气中。它包括醇、醛、酮、酯和有机酸。本文的重点是前两者,主要阐述了二方面内容：⑴植物军发性化合物的生物合成和释放机理。⑵环境因子（如温度、光照、水分胁迫、营养、CO2浓度、空气湿度）及植物的发育阶段、机械损伤和昆虫取食等对植物挥发性化合物合成与释放的影响机制。     

环境因子对植物释放挥发性化合物的影响

对近年来有关环境因子与植物释放挥发性化合物关系的研究进展进行了综合和概括。本文主要包括3类挥发性化合物。（1）异戊二烯是由叶绿体产生并且直接释放到大气中的C5化合物。（2）单萜类化合物是一类环状或非环状的C10化合物,它在植物体内合成后首先贮存于体内的特殊结构中（如树脂道、油腺）,然后由此通过气孔向大气中释放。（3）含氧挥发性化合物以各种形式释放到大气中。它包括醇、醛、酮、酯和有机酸。本文的重点是前两者, 主要阐述了二方面内容：(1)植物挥发性化合物的生物合成和释放机理。(2)环境因子（如温度、光照、水分胁迫、营养、CO2浓度、空气湿度）及植物的发育阶段、机械损伤和昆虫取食等对植物挥发性化合物合成与释放的影响机制。     

Gastropod grazing on a benthic alga leads to liberation of food‐finding infochemicals

Chemical information transfer is a major agent in the regulation of interspecific and intraspecific interactions in natural ecosystems. One important group of such infochemicals both in terrestrial and aquatic ecosystems are so‐called volatile organic compounds (VOCs) that can evoke behavioral or physiological responses like predator avoidance and mate or host location. In previous work, we have demonstrated that freshwater gastropods utilize VOCs released from benthic algae as food finding cues, although the specific nature of the VOC release and perception were not yet clear. Therefore we tested whether gastropod grazing on biofilms leads to algal cell damage and a subsequent liberation of wounding‐associated VOCs. In bioassays we investigated the algal VOC bouquet level which is necessary to elicit a behavioural response of freshwater gastropods. The results of the liberation experiment showed that gastropod grazing leads to VOCs release. We also found that a certain threshold level of volatiles is necessary for snails to recognise the volatile infochemicals and subsequently respond with a directed foraging behaviour towards the odour. Finally, a calculated mass balance model demonstrated that the grazer mediated VOC release produced a signal concentration that is sufficient to be recognized by conspecifics and utilized as foraging infochemicals. The emission of ecologically relevant volatiles through snail grazing with subsequent attraction of other gastropod grazers to algal biofilms indicates an important but so far understudied chemical signaling mechanism of ecological importance.     

Low-molecular-weight metabolites of aquatic macrophytes growing on the territory of Russia and their role in hydroecosystems

This article deals with the issues of studying low-molecular-weight volatile organic compounds (VOCs) of aquatic macrophytes growing in Russia under different environmental conditions and geographic regions. It is shown that the composition of VOCs and their content depend on the abiotic (geographical location of habitats, hydrological regime, and light conditions) and biotic factors (season and vegetation phase, distribution in different vegetative organs). Special attention has been paid to the functions performed by VOCs in aquatic ecosystems and their possible use for controlling phytoplankton development and algal “blooms” in inland water bodies.     

Ecological functions of volatile organic compounds in aquatic systems

In terrestrial ecosystems, volatile organic compounds (VOCs) are widely acknowledged as an important group of infochemicals. They play a major role in pollinator attraction by terrestrial plants and as insect pheromones. Furthermore, they are the mediating agent of so-called 'tritrophic interactions'. When plants are attacked by herbivorous insects, volatile signal substances are emitted, which act as attractants for parasitoids that kill the herbivores, thereby protecting the plant from herbivory. Despite the generally acknowledged importance of VOCs in terrestrial chemical ecology, their functions in aquatic food webs are largely unknown. VOCs produced by algae and cyanobacteria are a major concern in water processing, since aquatic primary producers are the reason for regularly encountered taste and odour problems in drinking water. Only very recently, research in aquatic chemical ecology has started to investigate possible ecological functions for the production of VOCs by algae and cyanobacteria. Volatile aldehydes released by wounded cells of marine planktonic diatoms seem to act as defensive compounds against herbivorous copepods on the population level. Just recently, it was found that VOCs released from benthic algae and cyanobacteria can be utilised as food and/or habitat finding cues by aquatic invertebrates such as freshwater gastropods and nematodes. Here, I review concepts and recent experimental studies on the ecological functions of such VOCs in aquatic ecosystems. Understanding the factors that lead to the liberation of volatile compounds is an essential prerequisite to properly assessing their ecological functions. It appears that (similar to terrestrial plant-herbivore interactions) VOCs can also play a steering role for both attraction and defence in aquatic ecosystems.     

The effects of season and water availability on chemical composition,secondary metabolites and biological activity in plants

Plants react towards changes in their environment, which can be a result of biotic or abiotic activities. Numerous studies have investigated the effects of abiotic stress on plants, and how it affects the primary as well as secondary metabolism. Generally it is accepted that plants react to environmental stress by increasing secondary metabolites. This is however a very broad and simplified explanation and often inaccurate. Various examples are provided where plants react positively, and often negatively towards seasonal variation and water availability, resulting in a lowering of certain secondary metabolites concentration, while others are increased. Furthermore species differences, cultivars and interaction of other environmental factors such as temperature complicates a simple conclusion from the effect of stress on plants. The differential expression of genes in different species and in different metabolic pathways ensures a complex and very specific reaction of a plant to environmental stress. Overall the paper provides support for a complex and intricate response system which differs for each plant species, and could be explained by understanding and studying the different metabolic pathways responsible for secondary metabolite production.     

Volatile organic compounds produced by human skin cells

Skin produces volatile organic compounds (VOCs) released to the environment with emission patterns characteristic of climatic conditions. It could be thought that these compounds are intermediaries in cell metabolism, since many intermediaries of metabolic pathways have a volatile potential. In this work, using gas chromatography, we answered the question of whether VOC profiles of primary cultures of human dermal fibroblasts were affected by the type of culture conditions. VOCs were determined for different types of culture, finding significant differences between skin cells grown in classical monolayer culture -2D- compared with 3D matrix immobilized cultures. This indicates that VOC profiles could provide information on the physiological state of skin cells or skin.     

Volatile organic compounds in the salt-lake sediments of the Tibet Plateau influence prokaryotic diversity and community assembly

Extremophiles - Volatile organic compounds (VOCs) are important environmental factors because they supply nutrients for microbial cells and mediate intercellular interactions. However, few studies...     

Volatile-mediated signalling in barley induces metabolic reprogramming and resistance against the biotrophic fungus Blumeria hordei

• Plants have evolved diverse secondary metabolites to counteract biotic stress. Volatile organic compounds (VOCs) are released upon herbivore attack or pathogen infection. Recent studies suggest that VOCs can act as signalling molecules in plant defence and induce resistance in distant organs and neighbouring plants. However, knowledge is lacking on the function of VOCs in biotrophic fungal infection on cereal plants.
• We analysed VOCs emitted by 13 ± 1-day-old barley plants (Hordeum vulgare L.) after mechanical wounding using passive absorbers and TD-GC/MS. We investigated the effect of pure VOC and complex VOC mixtures released from wounded plants on the barley–powdery mildew interaction by pre-exposure in a dynamic headspace connected to a powdery mildew susceptibility assay. Untargeted metabolomics and lipidomics were applied to investigate metabolic changes in sender and receiver barley plants.
• Green leaf volatiles (GLVs) dominated the volatile profile of wounded barley plants, with (Z)-3-hexenyl acetate (Z3HAC) as the most abundant compound. Barley volatiles emitted after mechanical wounding enhanced resistance in receiver plants towards fungal infection. We found volatile-mediated modifications of the plant–pathogen interaction in a concentration-dependent manner. Pre-exposure with physiologically relevant concentrations of Z3HAC resulted in induced resistance, suggesting that this GLV is a key player in barley anti-pathogen defence.
• The complex VOC mixture released from wounded barley and Z3HAC induced e.g. accumulation of chlorophyll, linolenic acid and linolenate-conjugated lipids, as well as defence-related secondary metabolites, such as hordatines in receiving plants. Barley VOCs hence induce a complex physiological response and disease resistance in receiver plants.