Chemical Signaling Mechanisms Research Articles

Implication of thermal signaling in neuronal differentiation revealed by manipulation and measurement of intracellular temperature

Neuronal differentiation—the development of neurons from neural stem cells—involves neurite outgrowth and is a key process during the development and regeneration of neural functions. In addition to various chemical signaling mechanisms, it has been suggested that thermal stimuli induce neuronal differentiation. However, the function of physiological subcellular thermogenesis during neuronal differentiation remains unknown. Here we create methods to manipulate and observe local intracellular temperature, and investigate the effects of noninvasive temperature changes on neuronal differentiation using neuron-like PC12 cells. Using quantitative heating with an infrared laser, we find an increase in local temperature (especially in the nucleus) facilitates neurite outgrowth. Intracellular thermometry reveals that neuronal differentiation is accompanied by intracellular thermogenesis associated with transcription and translation. Suppression of intracellular temperature increase during neuronal differentiation inhibits neurite outgrowth. Furthermore, spontaneous intracellular temperature elevation is involved in neurite outgrowth of primary mouse cortical neurons. These results offer a model for understanding neuronal differentiation induced by intracellular thermal signaling.

A Bacterial Quorum Sensing Molecule Elicits a General Stress Response in Saccharomyces cerevisiae.

Bacteria assess their population density through a chemical communication mechanism termed quorum sensing, in order to coordinate group behavior. Most research on quorum sensing has focused primarily on its role as an intraspecies chemical signaling mechanism that enables the regulation of certain phenotypes through targeted gene expression. However, in recent years several seminal studies have revealed important phenomena in which quorum sensing molecules appear to serve additional roles as interspecies signals that may regulate microbial ecology. In this study, we asked whether the budding yeast Saccharomyces cerevisiae can sense chemical signals from prokaryotes. When exposed to a variety of quorum sensing molecules from different bacterial species and from Candida albicans we found that N-(3-oxododecanoyl)-L-homoserine lactone (C12) from the opportunistic human pathogen Pseudomonas aeruginosa induces a remarkable stress response in yeast. Microarray experiments confirmed and aided in interpreting these findings, showing a unique and specific expression pattern that differed significantly from the response to previously described stress factors. We further characterized this response and report preliminary findings on the molecular basis for the recognition of C12 by the yeast.

Astrocytes promote ethanol-induced enhancement of intracellular Ca2+ signals through intercellular communication with neurons

SummaryEthanol (EtOH) abuse induces significant mortality and morbidity worldwide because of detrimental effects on brain function. Defining the contribution of astrocytes to this malfunction is imperative to understanding the overall EtOH effects due to their role in homeostasis and EtOH-seeking behaviors. Using a highly controllable in vitro system, we identify chemical signaling mechanisms through which acute EtOH exposure induces a modulatory feedback loop between neurons and astrocytes. Neuronally-derived purinergic signaling primed a subpopulation of astrocytes to respond to subsequent acute EtOH exposures (SEastrocytes: signal enhanced astrocytes) with greater calcium signal strength. Generation of SEastrocytes arose from astrocytic hemichannel-derived ATP and accumulation of its metabolite adenosine within the astrocyte microenvironment to modulate adenylyl cyclase and phospholipase C activity. These results highlight an important role of astrocytes in shaping the overall physiological responsiveness to EtOH and emphasize the unique plasticity of astrocytes to adapt to single and multiple exposures of EtOH.

Small Is Mighty-Chemical Communication Systems in Pseudomonas aeruginosa.

Pseudomonas aeruginosa is an opportunistic pathogen that causes a variety of acute and chronic infections. Usually a commensal on the host body, P. aeruginosa is capable of transforming into a virulent pathogen upon sensing favorable changes in the host immune system or stress cues. P. aeruginosa infections are hard to eradicate, because this pathogen has developed strong resistance to most conventional antibiotics; in addition, in chronic infections it commonly forms a biofilm matrix, which provides bacterial cells a protected environment to withstand various stresses including antibiotics. Given its importance as a human pathogen and its notorious antimicrobial tolerance, P. aeruginosa has been the subject of intensive investigations internationally. Research progress over the last two decades has unveiled a range of chemical communication systems in this pathogen. These diversified chemical communication systems endow P. aeruginosa a superb ability and remarkable flexibility to coordinate and modulate accordingly the transcriptional expression of various sets of genes associated with virulence and other physiologic activities in response to environmental changes. A fair understanding of the chemical signaling mechanisms with which P. aeruginosa governs virulence gene expression may hold the key to developing alternative therapeutic interventions that control and prevent bacterial infections.

Cross- species communication in bacterial world.

Biofilms are the compact association of micro organisms and the communication processes in these biofilms are always a wonder. Electrical and chemical signaling mechanism are the key to understand the bacterial communication network. Quorum sensing so far has been able to explain the coordinated motion of bacteria through its chemical signaling mechanism. Bacteria residing within biofilm communities are trivial to communicate. But the recent observation in 2017 by Humphries et al. has revealed that the ion channels enabled electrical signaling mechanism can be as powerful as to attract the distant cells i.e., this signaling mechanism are capable of holding a long range behavior. As a result long range cross species communication in the bacterial world have been possible. This substantial outcome has brought this field into a new paradigm to investigate the complex co-existence of biofilm communities and distant cells with a possible scope of application in synthetic biology. In this present article, we briefly describe this new signaling mechanism and how it gives rise to a long range communication ability in bacterial communities.

两种Eupristina属小蜂对宿主榕果挥发物和合成信息素的行为反应

PDF HTML阅读 XML下载 导出引用 引用提醒 两种Eupristina属小蜂对宿主榕果挥发物和合成信息素的行为反应 DOI: 10.5846/stxb201502130355 作者: 作者单位: 福建师范大学生命科学学院,福建师范大学生命科学学院,福建师范大学生命科学学院,福建师范大学生命科学学院,福建师范大学生命科学学院,福建师范大学生命科学学院,福建师范大学生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金重点资助项目（31270440）；福建师范大学生物学拔尖人才班科研项目；国家级、省级大学生创新训练计划项目 Responses of two Eupristina wasp species to fig volatiles of Ficus altissima and infochemicals Author: Affiliation: College of Life Science,Fujian Normal University,College of Life Science,Fujian Normal University,College of Life Science,Fujian Normal University,College of Life Science,Fujian Normal University,College of Life Science,Fujian Normal University,College of Life Science,Fujian Normal University,College of Life Science,Fujian Normal University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:高榕，雌雄同株，与其共生的形态高度相似的传粉小蜂Eupristina altissima与非传粉小蜂Eupristina sp.均为果内产卵。利用Y型嗅觉仪生物测定法研究E.altissima和Eupristina sp.对不同发育期高榕榕果挥发物以及合成信息素混合物的行为反应差异。结果表明：E.altissima和Eupristina sp.对高榕雌花期榕果挥发物具极显著趋向行为，对高榕雄花期榕果挥发物具极显著驱避行为，表明E.altissima与Eupristina sp.雌蜂能够敏锐辨别高榕雌花期和雄花期榕果的挥发物，快速远离雄花期榕果，并实现对宿主雌花期榕果的定位。但是，E.altissima与Eupristina sp.对其它发育时期榕果挥发物的行为反应具有差异性，前者对雌前期榕果和传粉或产卵后榕果释放的挥发物存在显著的趋避反应，而后者无明显的行为偏向性，表明E.altissima能够识别雌前期榕果和传粉或产卵后榕果，可避免误入其中而无法繁殖后代，Eupristina sp.则不具备这种识别能力。E.altissima和Eupristina sp.小蜂对合成信息素的行为反应也高度相似，表现为芳樟醇、苯乙烯，以及苯乙烯和金合欢醇的交互作用对两种小蜂选择行为影响显著，组合A1B2C2（0.5% Linalool+1% Benzyl ethylene+1% Farnesol）的混合信息素对两种小蜂具有极显著的驱避作用，而组合A2B1C1（1% Linalool+0.5% Benzyl ethylene+0.5% Farnesol），A2B1C2（1% Linalool+0.5% Benzyl ethylene+1% Farnesol），A2B2C1（1% Linalool+1% Benzyl ethylene+0.5% Farnesol）的混合信息素对其具有极显著的吸引作用，但两种小蜂对组合A1B1C1（0.5% Linalool+0.5% Benzyl ethylene+0.5% Farnesol）的行为反应存在差异。两种小蜂对榕果挥发物和合成信息素的反应异同，可能与其触角结构的差异密切相关。研究结果为探究榕-蜂共生体系的化学信号传导机制提供科学依据。 Abstract:Fig trees are pollinated by fig wasps, which also oviposit in female flowers. They had formed obligate mutualism in their long co-evolution process. Ficus altissima (Ficus, Moraceae) is a monoecious fig plant, both the pollinating Eupristina altissima and non-pollinating Eupristina sp. symbiosis with Ficus altissima were oviposited within the syconia. Pollinating Eupristina altissima and non-pollinating Eupristina sp were highly similar in morphology, only with a slight difference on body color, antenna, fore leg coxal comb and pollen pocket for their female wasps, no morphological differences found so far between their male wasps. Fig wasps mainly located their hosts by recognizing the chemical signal released from the syconia. Also the encounter of the mating partners is fundamental for the stability of their interaction, In this study, we applied a Y-tube (binary choice) olfactometer to test the responses of E. altissima and Eupristina sp. to fig volatiles of different developmental phase of Ficus altissima and infochemical mixture. Results showed that:(1) both E. altissima and Eupristina sp. represented significant preference to the fig volatiles of female syconia, and repelled to the fig volatiles of male flower phase syconia, indicating that E. altissima and Eupristina sp. can distinguish female flower phase syconia of Ficus altissima from the male one, and keep away from the male phase syconia in order to quickly localized its female host. Observation showed there are differences responses to fig volatiles of the other developmental phase between two wasp species. E. altissima significantly repelled to the fig volatiles of pre-female phase and post-pollinated or oviposited phase, while Eupristina sp. showed no significant preference between them, which indicated that E. altissima was able to recognize the syconia of pre-female phase and post-pollinated or oviposited phase and avoid entering into them, while Eupristina sp. can not. (2) E. altissima and Eupristina sp. also showed similary responses to infochemicals linalool, benzyl ethylene The interation of benzyl ethylene and farnesol significantly affected the choice behavior of both the two wasp species. Both wasp species repelled mix infochemicals of group A1B2C2(0.5% Linalool+1% Benzyl ethylene+1% Farnesol) significantly and significantly attracted by mix infochmicals of group A2B1C1(1% Linalool+0.5% Benzyl ethylene+0.5% Farnesol), A2B1C2(1% Linalool+0.5% Benzyl ethylene+1% Farnesol), A2B2C1(1% Linalool+1% Benzyl ethylene+0.5% Farnesol), while two wasp species showed difference responses to mix infochemical of group A1B1C1(0.5% Linalool+0.5% Benzyl ethylene+0.5% Farnesol). Above all, the two different wasp species can discriminate different volatile signals, and E. altissima was more favor to the fig volatiles of their host than Eupristina sp., therefore, E. altissima was able to locate their host more accurately than Eupristina sp. The different responses of E. altissima and Eupristina sp. to the fig volatiles and infochemicals may related to the different structure of their antenna. Our result will provide a scientific basis to the studies of chemical signaling mechanism of fig-wasp mutualism. 参考文献 相似文献 引证文献

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.

Active regulation of receptor ratios controls integration of quorum‐sensing signals in Vibrio harveyi

Quorum sensing is a chemical signaling mechanism used by bacteria to communicate and orchestrate group behaviors. Multiple feedback loops exist in the quorum-sensing circuit of the model bacterium Vibrio harveyi. Using fluorescence microscopy of individual cells, we assayed the activity of the quorum-sensing circuit, with a focus on defining the functions of the feedback loops. We quantitatively investigated the signaling input-output relation both in cells with all feedback loops present as well as in mutants with specific feedback loops disrupted. We found that one of the feedback loops regulates receptor ratios to control the integration of multiple signals. Together, the feedback loops affect the input-output dynamic range of signal transmission and the noise in the output. We conclude that V. harveyi employs multiple feedback loops to simultaneously control quorum-sensing signal integration and to ensure signal transmission fidelity.

Social behavior and pheromonal communication in reptiles

The role of pheromones in orchestrating social behaviors in reptiles is reviewed. Although all reptile orders are examined, the vast majority of the literature has dealt only with squamates, primarily snakes and lizards. The literature is surprisingly large, but most studies have explored relatively few behaviors. The evolution of chemical signaling in reptiles is discussed along with behaviors governed by pheromones including conspecific trailing, male-male agonistic interactions, sex recognition and sex pheromones, and reptilian predator recognition. Nonreptilian prey recognition by chemical cues was not reviewed. The recent literature has focused on two model systems where extensive chemical ecology studies have been conducted: the reproductive ecology of garter snakes and the behavioral ecology of Iberian lacertid lizards. In these two systems, enough is known about the chemical constituents that mediate behaviors to explore the evolution of chemical signaling mechanisms that affect life history patterns. In addition, these models illuminate natural and sexual selection processes which have lead to complex chemical signals whose different components and concentrations provide essential information about individuals to conspecifics. Reptiles provide excellent candidates for further studies in this regard not only in squamates, but also in the orders where little experimental work has been conducted to date.

Bacterium in a box: sensing of quorum and environment by the LuxI/LuxR gene regulatory circuit

The chemical signaling mechanism known as "bacterial quorum sensing" (QS) is normally interpreted as allowing bacteria to detect their own population density, in order to coordinate gene expression across a colony. However, the release of the chemical signal can also be interpreted as a means for one or a few cells to probe the local physical properties of their microenvironment. We have studied the behavior of the LuxI/LuxR QS circuit of Vibrio fischeri in tightly confining environments where individual cells detect their own released signals. We find that the lux genes become activated in these environments, although the activation onset time shows substantial cell-to-cell variability and little sensitivity to the confining volume. Our data suggest that noise in gene expression could significantly impact the utility of LuxI/LuxR as a probe of the local physical environment.

Specialized cells tag sexual and species identity in Drosophila melanogaster

Social interactions depend on individuals recognizing each other, and in this context many organisms use chemical signals to indicate species and sex. Cuticular hydrocarbon signals are used by insects, including Drosophila melanogaster, to distinguish conspecific individuals from others. These chemicals also contribute to intraspecific courtship and mating interactions. However, the possibility that sex and species identification are linked by common chemical signalling mechanisms has not been formally tested. Here we provide direct evidence that a single compound is used to communicate female identity among D. melanogaster, and to define a reproductive isolation barrier between D. melanogaster and sibling species. A transgenic manipulation eliminated cuticular hydrocarbons by ablating the oenocytes, specialized cells required for the expression of these chemical signals. The resulting oenocyte-less (oe(-)) females elicited the normal repertoire of courtship behaviours from males, but were actually preferred over wild-type females by courting males. In addition, wild-type males attempted to copulate with oe(-) males. Thus, flies lacking hydrocarbons are a sexual hyperstimulus. Treatment of virgin females with the aversive male pheromone cis-vaccenyl acetate (cVA) significantly delayed mating of oe(-) females compared to wild-type females. This difference was eliminated when oe(-) females were treated with a blend of cVA and the female aphrodisiac (7Z,11Z)-heptacosadiene (7,11-HD), showing that female aphrodisiac compounds can attenuate the effects of male aversive pheromones. 7,11-HD also was shown to have a crucial role in heterospecific encounters. Specifically, the species barrier was lost because males of other Drosophila species courted oe(-) D. melanogaster females, and D. simulans males consistently mated with them. Treatment of oe(-) females with 7,11-HD restored the species barrier, showing that a single compound can confer species identity. These results identify a common mechanism for sexual and species recognition regulated by cuticular hydrocarbons.

Chemical Signalling: Laser on the Fly Reveals a New Male-Specific Pheromone

A study using laser desorption/ionization mass spectrometry has identified new oxygenated compounds in cuticular lipids of the fruit fly Drosophila melanogaster; one such compound, when transferred to females during mating, renders the females unattractive to males for days.

Hydraulic and chemical signalling in the regulation of stomatal conductance and plant water use in field grapevines growing under deficit irrigation.

Effects of irrigation strategies on stomata and plant water use were studied in field-grown grapevines (Vitis vinifera L.). We assessed the importance of root-derived chemical signals vs. hydraulic signalling in stomatal regulation. The experiment included two treatments with the same water added to the soil (50% ETc) applied either to the whole root system (DI) or to half of the roots, alternating irrigation side every 15 days (PRD). Well-watered plants (FI) (100% ETc) and non-irrigated grapevines (NI) were also studied. Partial stomata closure occurred in both PRD and DI plants. [ABA] of xylem sap remained constant during the day and was maintained throughout the season, with higher values in NI plants. Xylem sap pH was not affected by soil water availability. A positive correlation between ψpd and maximum g s was found, indicating that grapevine stomata strongly respond to plant water status. In contrast, ABA did not explain stomatal control at veraison. At mid-ripening g s was significantly correlated with ABA, apparently interacting with the rise in xylem sap pH. Therefore, our data suggest that hydraulic feedback and feed-forward root-to-shoot chemical signalling mechanisms might be involved in the control of stomata in response to decreased soil water availability, hydraulic signals playing the dominant role.

Studies on hexactinellid sponges. II. Excitability, conduction and coordination of responses in rhabdocalyptus dawsoni (lambe, 1873)

Rhabdocalyptus can arrest its feeding current. The response is initiated by mechanical or electrical stimulation, and is coordinated through the sponge by a conduction system, having a precise excitability threshold and conducting on an all-or-none basis. All parts are excitable and conduct. Individuals in colonial assemblages are coordinated. Spontaneous as well as evoked arrests are observed. There is evidence of scattered pacemaker sites. Conduction is diffuse and unpolarized, and occurs with a velocity of 0.26 ± 0.07 cm s -1 at 11 °C. The conduction system is probably the trabecular syncytium. Isolated dermal membrane (‘pure’ trabecular tissue, without flagella or contractile elements) conducts. Mechanical and chemical signalling mechanisms are discussed. It is concluded that they cannot account for the phenomena observed, but that conduction must involve electrical impulses. The effectors responsible for current arrests are almost certainly the flagella of the flagellated chambers. It is assumed that they stop beating on receiving an arrest signal through the conduction pathway. The waveforms of arrests recorded with a thermistor flowmeter are best interpreted in terms of sudden, all-or-none cessation of pumping, with slow, gradual recovery of full pumping power. The flagella probably beat feebly at first on becoming active again following an arrest. The effector response shows a refractory period of 30 s. Responses occur with short latency. Delays are attributable to conduction time. The system is fatigueable. Numerous parallels exist with the behaviour of the stigmatal cilia in the ascidian branchial sac, both in the characteristics of the effector response and in the mechanism of coordination.