DOCSLIB.ORG

The Aer Protein and the Serine Chemoreceptor Tsr Independently

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Aer Protein and the Serine Chemoreceptor Tsr Independently Proc. Natl. Acad. Sci. USA Vol. 94, pp. 10541–10546, September 1997 Biochemistry The Aer protein and the serine chemoreceptor Tsr independently sense intracellular energy levels and transduce oxygen, redox, and energy signals for Escherichia coli behavior (signal transductionybacterial chemotaxisyaerotaxis) ANURADHA REBBAPRAGADA*, MARK S. JOHNSON*, GORDON P. HARDING*, ANTHONY J. ZUCCARELLI*†, HANSEL M. FLETCHER*, IGOR B. ZHULIN*, AND BARRY L. TAYLOR*†‡ *Department of Microbiology and Molecular Genetics and †Center for Molecular Biology and Gene Therapy, School of Medicine, Loma Linda University, Loma Linda, CA 92350 Edited by Daniel E. Koshland, Jr., University of California, Berkeley, CA, and approved July 17, 1997 (received for review May 6, 1997) ABSTRACT We identified a protein, Aer, as a signal conformational change in the signaling domain that increases transducer that senses intracellular energy levels rather than the rate of CheA autophosphorylation. The phosphoryl resi- the external environment and that transduces signals for due from CheA is transferred to CheY, which, in its phos- aerotaxis (taxis to oxygen) and other energy-dependent be- phorylated state, binds to a switch on the flagellar motors and havioral responses in Escherichia coli. Domains in Aer are signals a reversal of the direction of rotation of the flagella. similar to the signaling domain in chemotaxis receptors and Evidence that CheA, CheW, and CheY are also part of the the putative oxygen-sensing domain of some transcriptional aerotaxis response (12) led us to propose that the aerotaxis activators. A putative FAD-binding site in the N-terminal transducer would have (i) a C-terminal domain homologous to domain of Aer shares a consensus sequence with the NifL, Bat, the chemoreceptor signaling domain that modulates CheA and Wc-1 signal-transducing proteins that regulate gene autophosphorylation and (ii) a domain that senses oxygen. We expression in response to redox changes, oxygen, and blue have identified a putative aerotaxis transducer in a comput- light, respectively. A double mutant deficient in aer and tsr, erized search of protein databases and confirmed that this which codes for the serine chemoreceptor, was negative for protein, which we named ‘‘Aer,’’ functions as a transducer for aerotaxis, redox taxis, and glycerol taxis, each of which aerotaxis and related responses. We also present evidence that, requires the proton motive force andyor electron transport in addition to Aer, the serine chemoreceptor Tsr functions as system for signaling. We propose that Aer and Tsr sense the an independent transducer for aerotaxis and related responses. proton motive force or cellular redox state and thereby A preliminary report of these findings was presented at the integrate diverse signals that guide E. coli to environments Annual Meeting of the American Society for Biochemistry and where maximal energy is available for growth. Molecular Biology, 1996 (16). In an environment where oxygen is being depleted by growing MATERIALS AND METHODS bacteria, aerotaxis quickly moves Escherichia coli and Salmo- nella typhimurium to a more favorable microenvironment Bacterial Strains and Growth Conditions. The strains and before anoxia develops (1). Aerotaxis, the behavioral response plasmids used are listed in Table 1. Cells were grown in to oxygen, requires a functional electron transport system (2). Luria–Bertani medium containing 1 mM thiamine at 35°C to Oxygen stimulates electron transport through the electron OD600 5 0.45–0.50, unless specified otherwise. transport system, increasing the proton motive force (2, 3). A Construction of Mutants. A 1.2-kb kanamycin cassette postulated aerotaxis-transducing protein responds to the in- excised from pMB2190 (a derivative of pUC4K obtained from crease in electron transportyproton motive force and initiates P. Matsumura, University of Illinois, Chicago) using HincII a signal for the behavioral response to oxygen (3–6). Chemicals was ligated into pGH1 at the SmaI site (nt 349) of aer. The other than oxygen that stimulate electron transport also elicit aer-2::kan construct was excised with XmnI and EheI and an aerotaxis-like behavioral response in bacteria (5, 7, 8). The ligated into the SmaI site of the temperature-sensitive plasmid aerotaxis transducer may mediate other types of bacterial pKO3 (kindly provided by G. M. Church, Harvard University, behavior, such as the newly described taxis to a preferred redox Cambridge, MA). Mutants defective for aer were generated by potential (9) and energy taxis to carbon sources, such as allelic exchange as described by Hamilton et al. (23) and glycerol (10) or proline (11). Each of these behaviors involves modified by Link (24). The pKO3 vector contains a Bacillus modulation of the proton motive force and electron transport subtilis sacB gene that inhibits Escherichia coli growth in the as the initial sensory transduction event (3). presence of sucrose and facilitates the selection of cells that The aerotaxis sensory transduction pathway includes three have lost the vector sequence. Gene replacement was verified proteins that are common to the chemotaxis pathway: the by PCR using Expand Long Taq Polymerase (Boehringer CheA sensor kinase, CheY cognate response regulator, and Mannheim)(25) and Southern blot analysis of the transfor- CheW docking protein (12). The methyl-accepting chemotaxis mants. The absence of fusion products was confirmed by receptors Tsr, Tar, Trg, and Tap (13–15) span the cytoplasmic sequencing the inactivated gene. membrane and have a highly conserved signaling sequence in The aer tsr double mutant BT3311 was generated by P1 thr1 tsr the C-terminal cytoplasmic domain that binds CheA and transduction of a D -7021 fragment from RP5882 into BT3309 (aer-2) recipient cells and by selecting for threonine1 CheW. Repellent binding to a chemotaxis receptor induces a transductants. Colonies that lacked serine taxis on tryptone The publication costs of this article were defrayed in part by page charge This paper was submitted directly (Track II) to the Proceedings office. payment. This article must therefore be hereby marked ‘‘advertisement’’ in Abbreviation: IPTG, isopropylthiogalactoside. accordance with 18 U.S.C. §1734 solely to indicate this fact. A commentary on this article begins on page 10487. © 1997 by The National Academy of Sciences 0027-8424y97y9410541-6$2.00y0 ‡To whom reprint requests should be addressed. e-mail: blTaylor@ PNAS is available online at http:yywww.pnas.org. ccmail.llu.edu. 10541 Downloaded by guest on September 30, 2021 10542 Biochemistry: Rebbapragada et al. Proc. Natl. Acad. Sci. USA 94 (1997) Table 1. Strains and plasmids used in this study sequenced by the Blatner group in the E. coli Genome Project and deposited in the GenBank database (accession no. Strainsy U28379). The sequence currently is listed as AIRoECOLI in plasmids Relevant genotype Sourceyreference the SwissProt database (accession no. P50466). Transcription Strains of the ORF506 gene is independent of the flanking ygjG and MM335 wild type (17) yqjI genes. A computerized search revealed that the putative RP437 wild type (18) product of the ORF506 was a 506-residue protein that had a GK100 Dcyo Dcyd (19) predicted C-terminal segment with 96.7% identity to a highly RP5882 D(tsr) 7021 (20) conserved domain of Tsr (Fig. 1C). The N-terminal domain of BT3300 MM335 aer-2::kan This study the ORF506 protein (residues 8–129) shares homology with BT3309 RP437 aer-2::kan This study domains in the NifL protein of Azotobacter vinelandii (28% BT3310 BT3309ypGH1 (Aer11) This study identity, 52% similarity), the Bat protein of Halobacterium BT3360 MM335ypGH1 (Aer11) This study salinarium (22% identity, 54% similarity) and Wc-1, the White BT3311 aer-2::kan Dtsr This study Collar protein of Neurospora crassa (19% identity, 37% sim- BT3313 BT3311ypJL3 (Tsr11) This study ilarity) (Fig. 1A). Both NifL and Bat are known oxygen sensors. Plasmids In response to oxygen, the NifL protein regulates expression of pK03 rep pSC101(ts) sacB G. M. Church* nitrogen fixation genes (33), and the Bat protein regulates q pTrc99A ptac lacI Pharmacia and (21) synthesis of bacteriorhodopsin (34). The Wc-1 protein is a pGH1 pTrc99A aer1 This study central regulator of blue light responses in Neurospora (35). q 1 pJL3 ptac lacI tsr (22) Thus, the ORF506 protein had the expected domains of the *Harvard University, Cambridge, MA. putative aerotaxis-transducing protein (12), and the gene was renamed ‘‘aer’’ (aerotaxis and energy responses) after exper- semisoft agar were further characterized by temporal chemo- imental evidence confirmed its function. taxis assays. Sequence analysis predicted that the topology of Aer in the Overexpression of Aer and Tsr. The expression vector pGH1 membrane is different from the topology of known chemotaxis was constructed by subcloning a 1.5-kb AflIII–SalI PCR frag- receptors that transverse the cytoplasmic membrane (TM1 and ment containing the aer gene into the NcoI and SalI sites of TM2) at either end of a periplasmic ligand-binding domain. pTrc99A and was verified by sequencing. pGH1 was intro- Only one hydrophobic sequence (residues 167–206) was pre- duced into BT3309 cells by electroporation and was induced dicted in Aer. This sequence and these flanking regions are with varying amounts of isopropylthiogalactoside (IPTG). q similar to the TM1 and TM2 transmembrane regions of Tsr The plasmid pJL3 (22) containing the lacI repressor gene (Fig. 1B) but lack the intervening periplasmic
Load more

Recommended publications
  • The Effect of Carotid Chemoreceptor Inhibition on Exercise Tolerance in Chronic Obstructive Pulmonary Disease: a Randomized-Controlled Crossover Trial
    Respiratory Medicine 160 (2019) 105815 Contents lists available at ScienceDirect Respiratory Medicine journal homepage: http://www.elsevier.com/locate/rmed The effect of carotid chemoreceptor inhibition on exercise tolerance in chronic obstructive pulmonary disease: A randomized-controlled crossover trial a,b � a,c a a Devin B. Phillips , Sophie E. Collins , Tracey L. Bryan , Eric Y.L. Wong , M. Sean McMurtry d, Mohit Bhutani a, Michael K. Stickland a,e,* a Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Canada b Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Canada c Faculty of Rehabilitation Medicine, University of Alberta, Canada d Division of Cardiology, Faculty of Medicine and Dentistry, University of Alberta, Canada e G.F. MacDonald Centre for Lung Health, Covenant Health, Edmonton, Alberta, Canada ARTICLE INFO ABSTRACT Keywords: Background: Patients with chronic obstructive pulmonary disease (COPD) have an exaggerated ventilatory COPD response to exercise, contributing to exertional dyspnea and exercise intolerance. We recently demonstrated Exercise tolerance enhanced activity and sensitivity of the carotid chemoreceptor (CC) in COPD which may alter ventilatory and Carotid chemoreceptor cardiovascular regulation and negatively affect exercise tolerance. We sought to determine whether CC inhibi­ Dyspnea tion improves ventilatory and cardiovascular regulation, dyspnea and exercise tolerance in COPD. Methods: Twelve mild-moderate COPD patients (FEV1 83 � 15 %predicted) and twelve age- and sex-matched healthy controls completed two time-to-symptom limitation (TLIM) constant load exercise tests at 75% peak À À power output with either intravenous saline or low-dose dopamine (2 μg⋅kg 1⋅min 1, order randomized) to inhibit the CC.
    [Show full text]
  • Visions & Reflections on the Origin of Smell: Odorant Receptors in Insects
    Cell. Mol. Life Sci. 63 (2006) 1579–1585 1420-682X/06/141579-7 DOI 10.1007/s00018-006-6130-7 Cellular and Molecular Life Sciences © Birkhäuser Verlag, Basel, 2006 Visions & Reflections On the ORigin of smell: odorant receptors in insects R. Benton Laboratory of Neurogenetics and Behavior, The Rockefeller University, 1230 York Avenue, Box 63, New York, New York 10021 (USA), Fax: +1 212 327 7238, e-mail: [email protected] Received 23 March 2006; accepted 28 April 2006 Online First 19 June 2006 Abstract. Olfaction, the sense of smell, depends on large, suggested that odours are perceived by a conserved mecha- divergent families of odorant receptors that detect odour nism. Here I review recent revelations of significant struc- stimuli in the nose and transform them into patterns of neu- tural and functional differences between the Drosophila ronal activity that are recognised in the brain. The olfactory and mammalian odorant receptor proteins and discuss the circuits in mammals and insects display striking similarities implications for our understanding of the evolutionary and in their sensory physiology and neuroanatomy, which has molecular biology of the insect odorant receptors. Keywords. Olfaction, odorant receptor, signal transduction, GPCR, neuron, insect, mammal, evolution. Olfaction: the basics characterised by the presence of seven membrane-span- ning segments with an extracellular N terminus. OR pro- Olfaction is used by most animals to extract vital infor- teins are exposed to odours on the ciliated endings of olf- mation from volatile chemicals in the environment, such actory sensory neuron (OSN) dendrites in the olfactory as the presence of food or predators.
    [Show full text]
  • Chemical and Electric Transmission in the Carotid Body Chemoreceptor Complex
    EYZAGUIRRE Biol Res 38, 2005, 341-345 341 Biol Res 38: 341-345, 2005 BR Chemical and electric transmission in the carotid body chemoreceptor complex CARLOS EYZAGUIRRE Department of Physiology, University of Utah School of Medicine, Research Park, Salt Lake City, Utah, USA ABSTRACT Carotid body chemoreceptors are complex secondary receptors. There are chemical and electric connections between glomus cells (GC/GC) and between glomus cells and carotid nerve endings (GC/NE). Chemical secretion of glomus cells is accompanied by GC/GC uncoupling. Chemical GC/NE transmission is facilitated by concomitant electric coupling. Chronic hypoxia reduces GC/GC coupling but increases G/NE coupling. Therefore, carotid body chemoreceptors use chemical and electric transmission mechanisms to trigger and change the sensory discharge in the carotid nerve. Key terms: carotid body, chemosensory activity, glomus cells. The subject of this short review is highly Years later, with the advent of the appropriate since we are honoring Prof. electron microscope, it was found that the Patricio Zapata who has been a pioneer in glomus cells were connected synaptically this field and has done extensive to the carotid nerve endings (for refs. see pharmacological studies on chemical Mc Donald, 1981; Verna, 1997). Then, the synaptic transmission in the carotid body. problems started because of the location of Dr. Zapata is an excellent scientist and clear core synaptic vesicles. At the time, teacher, and I dearly value him as a friend these structures were supposed to be a and colleague. marker of pre-synaptic elements, and in the carotid body, they appeared some times in the glomus cells but very often in NATURE OF THE CAROTID BODY INNERVATION carotid nerve endings.
    [Show full text]
  • The Role of Chemoreceptor Evolution in Behavioral Change Cande, Prud’Homme and Gompel 153
    Available online at www.sciencedirect.com Smells like evolution: the role of chemoreceptor evolution in behavioral change Jessica Cande, Benjamin Prud’homme and Nicolas Gompel In contrast to physiology and morphology, our understanding success. How an organism interacts with its environment of how behaviors evolve is limited.This is a challenging task, as can be divided into three parts: first, the sensory percep- it involves the identification of both the underlying genetic tion of diverse auditory, visual, tactile, chemosensory or basis and the resultant physiological changes that lead to other cues; second, the processing of this information by behavioral divergence. In this review, we focus on the central nervous system (CNS), leading to a repres- chemosensory systems, mostly in Drosophila, as they are one entation of the sensory signal; and third, a behavioral of the best-characterized components of the nervous system response. Thus, behaviors could evolve either through in model organisms, and evolve rapidly between species. We changes in the peripheral nervous system (PNS) (e.g. examine the hypothesis that changes at the level of [1 ]), or through changes in higher-order neural circuitry chemosensory systems contribute to the diversification of (Figure 1). While the latter remain elusive, recent work behaviors. In particular, we review recent progress in on chemosensation in insects illustrates how the PNS understanding how genetic changes between species affect shapes behavioral evolution. chemosensory systems and translate into divergent behaviors. A major evolutionary trend is the rapid Chemosensation in insects depends on three classes of diversification of the chemoreceptor repertoire among receptors expressed in peripheral neurons housed in species.
    [Show full text]
  • Signaling and Sensory Adaptation in Escherichia Coli Chemoreceptors
    Review Special Issue: Microbial Translocation Signaling and sensory adaptation in Escherichia coli chemoreceptors: 2015 update 1 2 3 John S. Parkinson , Gerald L. Hazelbauer , and Joseph J. Falke 1 Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112, USA 2 Department of Biochemistry, University of Missouri Columbia, Columbia, MO 65211, USA 3 Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA Motile Escherichia coli cells track gradients of attractant sensitivity to ambient conditions, allowing chemoreceptors and repellent chemicals in their environment with trans- to operate over a wide concentration range. membrane chemoreceptor proteins. These receptors How do chemoreceptors process stimulus and sensory operate in cooperative arrays to produce large changes adaptation signals? How do they control CheA activity in in the activity of a signaling kinase, CheA, in response to response to those signals? What is the structure of the core small changes in chemoeffector concentration. Recent receptor signaling complex? How are those units net- research has provided a much deeper understanding of worked to produce cooperative signaling behavior? Over the structure and function of core receptor signaling the past few years of chemoreceptor research, molecular complexes and the architecture of higher-order receptor answers to these questions have come into sharper focus. arrays, which, in turn, has led to new insights into the In this brief review we summarize evidence for an emerg- molecular signaling mechanisms of chemoreceptor net- ing dynamics-based view of receptor operation and how it works. Current evidence supports a new view of recep- can account for transmission of stimulus and sensory tor signaling in which stimulus information travels adaptation signals through chemoreceptor molecules.
    [Show full text]
  • Olfactory Sensitivity in Mammalian Species
    Physiol. Res. 65: 369-390, 2016 https://doi.org/10.33549/physiolres.932955 REVIEW Olfactory Sensitivity in Mammalian Species M. WACKERMANNOVÁ1, L. PINC2, †L. JEBAVÝ3 1Department of Zoology and Fisheries, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Czech Republic, 2Canine Behavior Research Center, Department of Animal Science and Ethology, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Czech Republic, 3Department of Animal Science and Ethology, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Czech Republic Received November 13, 2014 Accepted February 5, 2016 On-line April 12, 2016 Summary Corresponding author Olfaction enables most mammalian species to detect and M. Wackermannová, Department of Zoology and Fisheries, discriminate vast numbers of chemical structures called odorants Faculty of Agrobiology, Food and Natural Resources, Czech and pheromones. The perception of such chemical compounds is University of Life Sciences Prague, Kamycka 129, 160 00 mediated via two major olfactory systems, the main olfactory Prague 6, Czech Republic. E-mail: [email protected] system and the vomeronasal system, as well as minor systems, such as the septal organ and the Grueneberg ganglion. Distinct Introduction differences exist not only among species but also among individuals in terms of their olfactory sensitivity; however, little is Chemosensory systems develop very early in known about the mechanisms that determine these differences. ontogeny and are found in almost every animal. The In research on the olfactory sensitivity of mammals, scientists mammalian sense of smell detects and discriminates thus depend in most cases on behavioral testing.
    [Show full text]
  • Taste Smell Touch „Chemical“ Senses
    Senses II taste smell touch „Chemical“ senses . Chemical senses – sense of taste and smell . Chemoreceptors respond to chemical compounds dissolved in water . Taste – substances dissolved in saliva . Smell – substances dissolved in nasal mucosa Sense of taste . There is about 10 000 taste buds located on the tongue . Taste buds are located in tongue papillas . Three main types of papillas . philiform, fungiform, a circumvallate . fungiform and circumvalatte contains taste buddies Anatomy of taste buddies . Each taste buds consists of 3 main types of cells: . support cells – surrounding receptor cell . basal cells – „stem“ cells . chemoreceptor itsef – taste cells Sense of taste Figure 15.1 Taste feelings . Five (Six) main taste perceptions . sweet – sugar, saccharine, alcohol, some aminoacids . salty – iron ions . sour – H+ ions . bitter – alcaloids as e.g. chinidin, nicotin . umami – glutamic acid . fat – fatty acids Sense of taste . To percept and feel, the chemical compound must: . dissolve in salive . to get into contact with cilia on taste cells . Substance bounding to cilia will: . depolarize membrane of taste receptor, and neurotransmitter is released . generator action potential is formed, that will trigger action potential Examples of some human thresholds Taste Substance Threshold for tasting Salty NaCl 0.01 M Sour HCl 0.0009 M Sweet Sucrose 0.01 M Bitter Quinine 0.000008 M Umami Glutamate 0.0007 M Sweet 1-propyl-2 amino-4- 0.00002 M nitrobenzene Sweet Lactose 0.03 M CNS pathway . Head nerved VII, IX and X carry the action potential from taste buddies into solitary nuclei in medulla oblongata . These impulses are led through thalamus into: . cortex (insula frontal cortex) .
    [Show full text]
  • Regulation of Ventilation
    CHAPTER 1 Regulation of Ventilation © IT Stock/Polka Dot/ inkstock Chapter Objectives By studying this chapter, you should be able to do 5. Describe the chemoreceptor input to the brain the following: stem and how it modifi es the rate and depth of breathing. 1. Describe the brain stem structures that regulate 6. Explain why it is that the arterial gases and pH respiration. do not signifi cantly change during moderate 2. Defi ne central and peripheral chemoreceptors. exercise. 3. Explain what eff ect a decrease in blood pH or 7. Discuss the respiratory muscles at rest and carbon dioxide has on respiratory rate. during exercise. How are they infl uenced by 4. Describe the Hering–Breuer reflex and its endurance training? function. 8. Describe respiratory adaptations that occur in response to athletic training. Chapter Outline Passive and Active Expiration Eff ects of Blood PCO 2 and pH on Ventilation Respiratory Areas in the Brain Stem Proprioceptive Refl exes Dorsal Respiratory Group Other Factors Ventral Respiratory Group Hering–Breuer Refl ex Apneustic Center Ventilation Response During Exercise Pneumotaxic Center Ventilation Equivalent for Oxygen () V/EOV 2 Chemoreceptors Ventilation Equivalent for Carbon Dioxide Central Chemoreceptors ()V/ECV O2 Peripheral Chemoreceptors Ventilation Limitations to Exercise Eff ects of Blood PO 2 on Ventilation Energy Cost of Breathing Ventilation Control During Exercise Chemical Factors Copyright ©2014 Jones & Bartlett Learning, LLC, an Ascend Learning Company Content not final. Not for sale or distribution. 17097_CH01_Pass4.indd 3 10/12/12 2:13 PM 4 Chapter 1 Regulation of Ventilation Passive and Active Expiration Ventilation is controlled by a complex cyclic neural process within the respiratory Brain stem Th e lower part centers located in the medulla oblongata of the brain stem .
    [Show full text]
  • Afferents Integration and Neural Adaptive Control of Breathing by Chung Tin
    Afferents Integration and Neural Adaptive Control of Breathing by Chung Tin B.Eng., Mechanical Engineering, The University of Hong Kong, 2002 S.M., Mechanical Engineering, Massachusetts Institute of Technology, 2004 SUBMITTED TO THE DEPARTMENT OF MECHANICAL ENGINEERING IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN MECHANICAL ENGINEERING AT THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY JUNE 2011 @ 2011 Massachusetts Institute of Technology. All rights reserved. Signature of A uthor ..................... ....... .... ...* .. ........ ................................... Dep a ent of Mechanical Engineering May 19,2011 C ertified by ........................................... ............... .... ........................................... / Chi-Sang Poon Principal Research Scientist of Health Sciences & Technology Thesis Supervisor C ertified by ................................9 .- .. ............ y .... ... .................................... Neville Hogan Sun Jae Professor of Mechanical Engineering Professor of Brain and Cognitive Sciences TesiComnuittee Chair A ccepted by ................................................................. ... ............................................ David E. Hardt Ralph E. and Eloise F. Cross Professor of Mechanical Engineering Chairman, Committee on Graduate Students Afferents Integration and Neural Adaptive Control of Breathing by Chung Tin Submitted to the Department of Mechanical Engineering On May 19, 2011, in Partial Fulfillment of the Requirements for the Degree
    [Show full text]
  • The Senses Reception of a Stimulus
    The Senses eg. individual sensitivities, eg colorblindness we spend our lives in an ocean of sensory stimuli: ! unusual pathways, eg synesthesia light gravity electrical currents vibrations time our survival depends on our ability to perceive, interpret and respond to these signals Reception vs Perception Reception is the mechanism and structures involved in detecting and transmitting sensory information our body has millions of sensory receptors All sensory receptors are “connected to” our CNS by way of sensory neurons these neurons travel through the Cranial or Spinal nerves to the brain or spinal cord Perception is the conscious awareness of sensory stimuli is a higher level process of integration and interpretation depends on how the brain processes the signals it is receiving Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 1 Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 2 photoreceptor - light Reception of a Stimulus chemoreceptor - chemicals mechanoreceptor - bending, pressure, touch Reception of a sensation is determined by: thermoreceptor - temperature osmoreceptor – salt/water conc 1. Source of Sensory Stimuli baroreceptor - fluid pressure each sensory receptor is designed to transduce we can classify receptors by their location or only one kind of stimulus regardless of the source of the stimulus they respond to: how it is stimulated a. exteroceptors eg hard hit on head ! “see stars” near surface of body eg. spicy food monitor external environment eg. menthol cough drop most special senses 3. Density of Receptors & Size of Receptive b. visceroceptors (interoceptors) Field deep monitor internal environment 99% of receptors in body not evenly distributed over surface of body c.
    [Show full text]
  • A Chronic Pain: Inflammation-Dependent Chemoreceptor Adaptation in Rat Carotid Body
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Digital.CSIC A CHRONIC PAIN: INFLAMMATION-DEPENDENT CHEMORECEPTOR ADAPTATION IN RAT CAROTID BODY X. Liu1, L. He1, B. Dinger1, C. Gonzalez2, L. Stensaas1 and S. Fidone1 1Department of Physiology, University of Utah School of Medicine, Salt Lake City, UT, USA. 2Departamento de Bioquímica y Biología Molecular y Fisiología,Instituto de Biología y Genética Molecular y CIBER de Enfermedades Respiratorias, Universidad de Valladolid, Consejo Superior de Investigaciones Científicas e Instituto Carlos III. Facultad de Medicina 47005 Valladolid, Spain. Running head: Inflammation and Chemoreceptor Adaptation Corresponding author: Dr. Bruce Dinger Department of Physiology University of Utah School of Medicine 420 Chipeta Way Salt Lake City, UT, 84108, USA Abstract Experiments in recent years have revealed labile electrophysiological and neurochemical phenotypes in primary afferent neurons exposed to specific stimulus conditions associated with the development of chronic pain. These studies collectively demonstrate that the mechanisms responsible for functional plasticity are primarily mediated by novel neuroimmune interactions involving circulating and resident immune cells and their secretory products, which together induce hyperexcitability in the primary sensory neurons. In another peripheral sensory modality, namely the arterial chemoreceptors, sustained stimulation in the form of chronic hypoxia (CH) elicits increased chemoafferent excitability from the mammalian carotid body. Previous studies which focused on functional changes in oxygen-sensitive type I cells in this organ have only partially elucidated the molecular and cellular mechanisms which initiate and control this adaptive response. Recent studies in our laboratory indicate a unique role for the immune system in regulating the chemo-adaptive response of the carotid body to physiologically relevant levels of hypoxia.
    [Show full text]
  • Chapter 6 the Chemosensory System of Caenorhabditis
    CHAPTER 6 THE CHEMOSENSORY SYSTEM OF CAENORHABDITIS ELEGANS AND OTHER NEMATODES DAMIEN M. O’HALLORAN, DAVID A. FITZPATRICK AND # ANN M. BURNELL Institute of Bioengineering and Agroecology, Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland. # Corresponding author. E-mail: [email protected] Abstract. Olfactory systems allow organisms to detect and discriminate between thousands of low molecular mass, mostly organic, compounds which we call odours. Organisms as diverse as humans and nematodes utilize the same basic mechanisms for this sensory perception. Represented in the olfactory repertoire of both vertebrates and invertebrates are aliphatic and aromatic compounds with diverse functional groups including aldehydes, esters, ketones, alcohols, ethers, carboxylic acids, amines, halides and sulphides. Soil-dwelling nematodes encounter many types of volatile and water-soluble molecules in their environment; successful foraging depends on the animal’s ability to detect a gradient in one odorant while ignoring extraneous odours. Water-soluble chemicals tend to diffuse slowly in the soil and may provide short-range chemosensory cues whereas volatile compounds diffuse more rapidly and thus can be used for long-range chemotaxis to distant food sources. Animals modify their behaviour based on the interpretation of these environmental cues. The biochemical and physiological processes of chemosensory perception involve the recognition of small chemical molecules by specialized transduction pathways in the organism. These pathways are responsible for the transformation of information from extrinsic molecules into signals that the nervous system can interpret. The highly conserved G-protein signalling pathway is used to provide this chemosensory ability. The interaction of an odorant with an olfactory receptor results in the activation of heterotrimeric GTP-binding proteins (G proteins).
    [Show full text]