Sensing pH?

Abstract. pH is an all-pervasive variable in the environment of phototrophs. Phototrophs as a whole, and even the single genus Dunaliella , can grow over essentially the whole range of pH values found in nature. Such a large range of pH values, combined with other chemical variations in the environment, impose a range of constraints on plant behaviour related to intracellular pH regulation, nutrient acquisition, and avoidance of toxic effects. No single genotype can grow well over the whole pH range compatible with growth of phototrophs as a whole, although some deliberately alter surface pH so as to create a 5–6 unit pH gradient over the surface related to nutrient acquisition and avoidance of toxic influences. The regulation of these various processes does not, on current evidence, involve pH-sensing by any extracellular sensor which is not part of the catalytic or regulatory mechanism of a membrane protein such as a porter.     

Sensing soil oxygen

Abstract. Under natural conditions where gaseous exchange between soil and atmosphere is restricted by excess water, the concentration of O₂ in the rooting zone can become very low while reduced ions and organic compounds that are potentially phytoxic may accumulate. Mechanisms by which shoots and roots detect, and adjust to, this O₂-deficient environment are reviewed. Injury to roots and their inability to function because of insufficient O₂ is communicated to the shoot in a variety of ways, so that it adjusts physiologically. Roots may acclimate metabolically to a gradual fall in O₂ supply, so that they either improve their tolerance of anoxia, or partially avoid O₂-deficiency by structural changes that aid internal transfer of O₂ to the roots from the shoot. Molecular mechanisms regulating such metabolic changes, including environmental cues, are discussed.     

Sensing a revolution

New fully integrated biosensors that monitor molecular and physiological parameters throughout our bodies are set to revolutionize medicine and personalized healthcare.     

Sensing the sea

The development of the 'ecosystem approach' to the management of marine systems is leading to a requirement for data to be collected with greater frequency and spatial resolution than has been necessary in the past. This is being met both by the analysis of more samples (to better describe variability and temporal change) and by the deployment of instrumented platforms that gather data over long time periods. To meet these requirements in the hostile conditions at sea, a range of sensors based on physical, chemical and biological responses is being developed. These sensors have applications in laboratory analysis of collected samples, during field studies and directly in situ at remote sites for real-time observations of environmental trends. Here, we consider the role that biosensors could have in future marine monitoring programmes.     

Sensing the epigenome

Recent studies of plant development and environmental stress responses have converged on the roles of RNA and its metabolism as primary regulators of gene action. This RNA-based system appears to represent a versatile platform both for maintaining epigenetic memory and for reprogramming gene control in response to external signals. The fast-paced research reviewed here highlights exciting new trends in plant research relating to mechanisms and roles of the RNA-dependent epigenome in both development and evolution.     

细菌密度感应系统抑制剂

许多条件致病菌依赖密度感应系统作为毒力表达的最重要的调节器。该文就革兰氏阴性细菌密度感应系统抑制剂的作用机制、分离与鉴定及应用等方面进行系统阐述。     

Sensing cell-secreted molecules

Fields of medicine and life sciences are constantly evolving and striving for improved understanding of how cells function at an individual level, small ensemble level, and tissue level. Such improved understanding will translate into developing therapeutic strategies as well as approaches for disease diagnosis. Behavior of cells at all levels is shaped in significant part by secreted molecules that serve as cues for proliferation, migration, death, and other cell life-altering events. Improved understanding of what signals released when by which cells requires novel tools for local detection of cell-secreted molecules. This paper reviews recent efforts by bioengineering and bioanalytical chemistry communities to develop biosensors for detecting molecules in extracellular space. Multiple topics including antibody-, enzyme- and aptamer-based biosensors for cell analysis as well as sensor miniaturization approaches are discussed.     

真菌中的群体感应系统

以胞间通讯信号分子介导的细菌群体感应参与细菌多种生理功能的调控是非常普遍的。近年的研究表明,真菌中也存在类似于细菌群体感应信号分子的调节分子,并且介导着真菌某些生理行为的调节。这一过程也称为真菌的群体感应系统。文中简要介绍真菌群体感应系统的研究进展,并讨论了真菌群体感应系统作为抗真菌感染靶点的可能性。     

Compressive Sensing DNA Microarrays

Compressive sensing microarrays (CSMs) are DNA-based sensors that operate using group testing and compressive sensing (CS) principles. In contrast to conventional DNA microarrays, in which each genetic sensor is designed to respond to a single target, in a CSM, each sensor responds to a set of targets. We study the problem of designing CSMs that simultaneously account for both the constraints from CS theory and the biochemistry of probe-target DNA hybridization. An appropriate cross-hybridization model is proposed for CSMs, and several methods are developed for probe design and CS signal recovery based on the new model. Lab experiments suggest that in order to achieve accurate hybridization profiling, consensus probe sequences are required to have sequence homology of at least 80% with all targets to be detected. Furthermore, out-of-equilibrium datasets are usually as accurate as those obtained from equilibrium conditions. Consequently, one can use CSMs in applications in which only short hybridization times are allowed.     

细菌中群体感应调节系统

细菌根据特定信号分子的浓度可以监测周围环境中自身或其它细菌的数量变化,当信号达到一定的浓度阈值时,能启动菌体中相关基因的表达来适应环境中的变化,这一调控系统被称为细菌的群体感应调节系统(QuorumSensing系统)。本文系统介绍了细菌感知种内与种间数量的群体感应调节系统,并阐述了植物针对病原菌这一信号系统的抗病策略。     

Sensing stretch is fundamental

Stretch induces changes in cardiomyocyte biology that are implicated in heart failure, but the mechanism by which stretch is sensed and signals are transduced is unknown. New understanding of the Z disc elements of contractile units are beginning to elucidate the mechanism of stretch sensing and its relation to cardiac adaptation and disease.     

Sensing with TRP channels

Drosophila melanogaster flies carrying the trp (transient receptor potential) mutation are rapidly blinded by bright light, because of the absence of a Ca2+-permeable ion channel in their photoreceptors. The identification of the trp gene and the search for homologs in yeast, flies, worms, zebrafish and mammals has led to the discovery of a large superfamily of related cation channels, named TRP channels. Activation of TRP channels is highly sensitive to a variety of chemical and physical stimuli, allowing them to function as dedicated biological sensors that are essential in processes such as vision, taste, tactile sensation and hearing.     

Sensing scenes with silicon

Scene analysis, the process of converting sensory information from peripheral receptors into a representation of objects in the external world, is central to our human experience of perception. Through our efforts to design systems for object recognition and for robot navigation, we have come to appreciate that a number of common themes apply across the sensory modalities of vision, audition, and olfaction; and many apply across species ranging from invertebrates to mammals. These themes include the need for adaptation in the periphery and trade-offs between selectivity for frequency or molecular structure with resolution in time or space. In addition, neural mechanisms involving coincidence detection are found in many different subsystems that appear to implement cross-correlation or autocorrelation computations.     

细菌群感效应的猝灭

细菌群感效应（quorum sensing,QS）是一种细菌种间和种内信息交流调控机制.研究证明,细菌群感效应与细菌生物膜的形成和某些人体、植物病原菌的发病机制有关,目前它已成为医学、生物工程、农业和环境工程等领域的研究热点,有望在此基础上开发出控制生物膜形成和病原菌致病性的新方法.该文介绍目前已有的细菌群感效应的抑制方法（即细菌群感猝灭,quorum quenching）,主要包括降低R蛋白活性、抑制信号分子合成,以及降解信号分子等.