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Bouhouche K, Valentine MS, Le Borgne P, Lemullois M, Yano J, Lodh S, Nabi A, Tassin AM, Van Houten JL. Paramecium, a Model to Study Ciliary Beating and Ciliogenesis: Insights From Cutting-Edge Approaches. Front Cell Dev Biol 2022; 10:847908. [PMID: 35359441 PMCID: PMC8964087 DOI: 10.3389/fcell.2022.847908] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 02/14/2022] [Indexed: 12/30/2022] Open
Abstract
Cilia are ubiquitous and highly conserved extensions that endow the cell with motility and sensory functions. They were present in the first eukaryotes and conserved throughout evolution (Carvalho-Santos et al., 2011). Paramecium has around 4,000 motile cilia on its surface arranged in longitudinal rows, beating in waves to ensure movement and feeding. As with cilia in other model organisms, direction and speed of Paramecium ciliary beating is under bioelectric control of ciliary ion channels. In multiciliated cells of metazoans as well as paramecia, the cilia become physically entrained to beat in metachronal waves. This ciliated organism, Paramecium, is an attractive model for multidisciplinary approaches to dissect the location, structure and function of ciliary ion channels and other proteins involved in ciliary beating. Swimming behavior also can be a read-out of the role of cilia in sensory signal transduction. A cilium emanates from a BB, structurally equivalent to the centriole anchored at the cell surface, and elongates an axoneme composed of microtubule doublets enclosed in a ciliary membrane contiguous with the plasma membrane. The connection between the BB and the axoneme constitutes the transition zone, which serves as a diffusion barrier between the intracellular space and the cilium, defining the ciliary compartment. Human pathologies affecting cilia structure or function, are called ciliopathies, which are caused by gene mutations. For that reason, the molecular mechanisms and structural aspects of cilia assembly and function are actively studied using a variety of model systems, ranging from unicellular organisms to metazoa. In this review, we will highlight the use of Paramecium as a model to decipher ciliary beating mechanisms as well as high resolution insights into BB structure and anchoring. We will show that study of cilia in Paramecium promotes our understanding of cilia formation and function. In addition, we demonstrate that Paramecium could be a useful tool to validate candidate genes for ciliopathies.
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Affiliation(s)
- K. Bouhouche
- CEA, CNRS, Université Paris-Saclay, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | | | - P. Le Borgne
- CEA, CNRS, Université Paris-Saclay, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - M. Lemullois
- CEA, CNRS, Université Paris-Saclay, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - J. Yano
- Department of Biology, University of Vermont, Burlington, VT, United States
| | - S. Lodh
- Biological Sciences, Marquette University, Milwaukee, WI, United States
| | - A. Nabi
- Luminex, Austin, TX, United States
| | - A. M. Tassin
- CEA, CNRS, Université Paris-Saclay, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - J. L. Van Houten
- Department of Biology, University of Vermont, Burlington, VT, United States
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Valentine MS, Van Houten J. Ion Channels of Cilia: Paramecium as a Model. J Eukaryot Microbiol 2022; 69:e12884. [PMID: 34995386 DOI: 10.1111/jeu.12884] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 12/27/2021] [Indexed: 11/29/2022]
Abstract
Holotrichous ciliates, like Paramecium, swim through their aqueous environment by beating their many cilia. They can alter swimming speed and direction, which seems to have mesmerized early microscopists of the 1600's. We know from extensive and elegant physiological studies and generation of mutants that these cells can be considered little swimming neurons because their ciliary beating is under bioelectric control of ion channels in the cilia. This chapter will focus on the ionic control of swimming behavior by ciliary ion channels, primarily in the holotrichous ciliate Paramecium. Voltage gated and calcium activated channels for calcium, magnesium, sodium, and potassium are regulated in a closely orchestrated manner that allows cilia to bend and propel the cell forward or backward. Sensory input that generates receptor potentials feeds into the control of this channel activity and allows the cell to turn or speed up. This in turn helps the cell to avoid predators or toxic conditions. While the focus is on P. tetraurelia and P. caudatum, the principles of ciliary ion channel activity and control are easily extendable to other ciliates and protists. The high conservation of channel and ion pump structures also extends the lessons from Paramecium to higher organisms.
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Affiliation(s)
- Megan S Valentine
- SUNY Plattsburgh, Department of Biological Sciences, 101 Broad Street, Plattsburgh, NY, USA, 518-564-3174
| | - Judith Van Houten
- University of Vermont, Department of Biology, University of Vermont, 109 Carrigan Drive, Burlington, 802-434-4006
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Valentine MS, Van Houten JL. Methods for Studying Ciliary-Mediated Chemoresponse in Paramecium. Methods Mol Biol 2018; 1454:149-68. [PMID: 27514921 DOI: 10.1007/978-1-4939-3789-9_10] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Paramecium is a useful model organism for the study of ciliary-mediated chemical sensing and response. Here we describe ways to take advantage of Paramecium to study chemoresponse.Unicellular organisms like the ciliated protozoan Paramecium sense and respond to chemicals in their environment (Van Houten, Ann Rev Physiol 54:639-663, 1992; Van Houten, Trends Neurosci 17:62-71, 1994). A thousand or more cilia that cover Paramecium cells serve as antennae for chemical signals, similar to ciliary function in a large variety of metazoan cell types that have primary or motile cilia (Berbari et al., Curr Biol 19(13):R526-R535, 2009; Singla V, Reiter J, Science 313:629-633, 2006). The Paramecium cilia also produce the motor output of the detection of chemical cues by controlling swimming behavior. Therefore, in Paramecium the cilia serve multiple roles of detection and response.We present this chapter in three sections to describe the methods for (1) assaying populations of cells for their behavioral responses to chemicals (attraction and repulsion), (2) characterization of the chemoreceptors and associated channels of the cilia using proteomics and binding assays, and (3) electrophysiological analysis of individual cells' responses to chemicals. These methods are applied to wild type cells, mutants, transformed cells that express tagged proteins, and cells depleted of gene products by RNA Interference (RNAi).
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Affiliation(s)
- Megan Smith Valentine
- Department of Biology, The University of Vermont, Room 120A, Marsh Life Science Building, 109 Carrigan Drive, Burlington, VT, 05405, USA
| | - Judith L Van Houten
- Department of Biology, The University of Vermont, Room 120A, Marsh Life Science Building, 109 Carrigan Drive, Burlington, VT, 05405, USA.
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Giuffre C, Hinow P, Vogel R, Ahmed T, Stocker R, Consi TR, Strickler JR. The ciliate Paramecium shows higher motility in non-uniform chemical landscapes. PLoS One 2011; 6:e15274. [PMID: 21494596 PMCID: PMC3073933 DOI: 10.1371/journal.pone.0015274] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 11/03/2010] [Indexed: 11/18/2022] Open
Abstract
We study the motility behavior of the unicellular protozoan Paramecium tetraurelia in a microfluidic device that can be prepared with a landscape of attracting or repelling chemicals. We investigate the spatial distribution of the positions of the individuals at different time points with methods from spatial statistics and Poisson random point fields. This makes quantitative the informal notion of “uniform distribution” (or lack thereof). Our device is characterized by the absence of large systematic biases due to gravitation and fluid flow. It has the potential to be applied to the study of other aquatic chemosensitive organisms as well. This may result in better diagnostic devices for environmental pollutants.
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Affiliation(s)
- Carl Giuffre
- Great Lakes WATER Institute, University of Wisconsin - Milwaukee, Milwaukee, Wisconsin, United States of America
| | - Peter Hinow
- Department of Mathematical Sciences, University of Wisconsin - Milwaukee, Wisconsin, United States of America
- * E-mail:
| | - Ryan Vogel
- School of Medicine, Saint Louis University, St. Louis, Missouri, United States of America
| | - Tanvir Ahmed
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Masschusetts, United States of America
| | - Roman Stocker
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Masschusetts, United States of America
| | - Thomas R. Consi
- Great Lakes WATER Institute, University of Wisconsin - Milwaukee, Milwaukee, Wisconsin, United States of America
| | - J. Rudi Strickler
- Great Lakes WATER Institute, University of Wisconsin - Milwaukee, Milwaukee, Wisconsin, United States of America
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Govorunova EG, Sineshchekov OA. Chemotaxis in the green flagellate alga Chlamydomonas. BIOCHEMISTRY (MOSCOW) 2006; 70:717-25. [PMID: 16097934 DOI: 10.1007/s10541-005-0176-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Behavior of the green flagellate alga Chlamydomonas changes in response to a number of chemical stimuli. Specific sensitivity of the cells to different substances might appear only at certain stages of the life cycle. The heterogamous species C. allensworthii demonstrates chemotaxis of male gametes towards pheromones excreted by female gametes. In C. reinhardtii chemotaxis towards tryptone occurs only in gametes, whereas chemotaxis towards ammonium, on the contrary, only in vegetative cells. Chemotaxis to different chemical stimuli might involve different mechanisms of reception and signal transduction, elucidation of which has only recently begun. Indirect evidences show that the cells likely respond to tryptone with changes in the membrane electrical conductance. The recently completed project of sequencing the whole nuclear genome of C. reinhardtii provides the basis for future identification of molecular elements of the chemosensory cascade in this alga.
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Affiliation(s)
- E G Govorunova
- Faculty of Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.
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Tsitolovsky LE. Protection from neuronal damage evoked by a motivational excitation is a driving force of intentional actions. ACTA ACUST UNITED AC 2005; 49:566-94. [PMID: 16269320 DOI: 10.1016/j.brainresrev.2005.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2004] [Revised: 12/16/2004] [Accepted: 02/25/2005] [Indexed: 01/13/2023]
Abstract
Motivation may be understood as an organism's subjective attitude to its current physiological state, which somehow modulates generation of actions until the organism attains an optimal state. How does this subjective attitude arise and how does it modulate generation of actions? Diverse lines of evidence suggest that elemental motivational states (hunger, thirst, fear, drug-dependence, etc.) arise as the result of metabolic disturbances and are related to transient injury, while rewards (food, water, avoidance, drugs, etc.) are associated with the recovery of specific neurons. Just as motivation and the very life of an organism depend on homeostasis, i.e., maintenance of optimum performance, so a neuron's behavior depends on neuronal (i.e., ion) homeostasis. During motivational excitation, the conventional properties of a neuron, such as maintenance of membrane potential and spike generation, are disturbed. Instrumental actions may originate as a consequence of the compensational recovery of neuronal excitability after the excitotoxic damage induced by a motivation. When the extent of neuronal actions is proportional to a metabolic disturbance, the neuron theoretically may choose a beneficial behavior even, if at each instant, it acts by chance. Homeostasis supposedly may be directed to anticipating compensation of the factors that lead to a disturbance of the homeostasis and, as a result, participates in the plasticity of motivational behavior. Following this line of thought, I suggest that voluntary actions arise from the interaction between endogenous compensational mechanisms and excitotoxic damage of specific neurons, and thus anticipate the exogenous compensation evoked by a reward.
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Affiliation(s)
- Lev E Tsitolovsky
- Department of Life Science, Bar-Ilan University, Ramat-Gan 52900, Israel.
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Sehring IM, Plattner H. Ca2+ oscillations mediated by exogenous GTP in Paramecium cells: assessment of possible Ca2+ sources. Cell Calcium 2005; 36:409-20. [PMID: 15451624 DOI: 10.1016/j.ceca.2004.04.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2004] [Revised: 02/27/2004] [Accepted: 04/05/2004] [Indexed: 11/20/2022]
Abstract
We applied exogenous guanosine trisphosphate, GTP, to Paramecium tetraurelia cells injected with Fura Red for analysing changes of free intracellular Ca(2+) concentrations, [Ca(2+)](i), during periodic back-/forward swimming thus induced. Strain ginA (non-responsive to GTP) shows no Ca(2+) signal upon GTP application. In strain nd6 (normal Ca(2+) signalling) an oscillating [Ca(2+)](i) response with a prominent first peak occurs upon GTP stimulation, but none after mock-stimulation or after 15 min adaptation to GTP. While this is in agreement with previous electrophysiological analyses, we now try to identify more clearly the source(s) of Ca(2+). Stimulation of nd6 cells, after depletion of Ca(2+) from their cortical stores (alveolar sacs), shows the same Ca(2+) oscillation pattern but with reduced amplitudes, and a normal behavioural response is observed. Stimulation with GTP, supplemented with the Ca(2+) chelator BAPTA, results in loss of the first prominent Ca(2+) peak, in reduction of the following Ca(2+) amplitudes, and in the absence of any behavioural response. Both these observations strongly suggest that for the initiation of GTP-mediated back-/forward swimming Ca(2+) from the extracellular medium is needed. For the maintenance of the Ca(2+) oscillations a considerable fraction must come from internal stores, probably other than alveolar sacs, rather likely from the endoplasmic reticulum.
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Affiliation(s)
- Ivonne M Sehring
- Department of Biology, University of Konstanz, P.O. Box 5560, 78457 Konstanz, Germany
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Yano J, Rachochy V, Van Houten JL. Glycosyl phosphatidylinositol-anchored proteins in chemosensory signaling: antisense manipulation of Paramecium tetraurelia PIG-A gene expression. EUKARYOTIC CELL 2004; 2:1211-9. [PMID: 14665456 PMCID: PMC326658 DOI: 10.1128/ec.2.6.1211-1219.2003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Glycosyl phosphatidylinositol (GPI)-anchored proteins are peripheral membrane proteins tethered to the cell through a lipid anchor. GPI-anchored proteins serve many functions in cellular physiology and cell signaling. The PIG-A gene codes for one of the enzymes of a complex that catalyzes the first step in anchor synthesis, and we have cloned the Paramecium tetraurelia pPIG-A gene using homology PCR. To understand the function of pPIG-A and the significance of GPI-anchored proteins in Paramecium, we reduced the mRNA for pPIG-A in transformed cells using an expression vector that transcribed antisense mRNA. The amount of transcript is reduced to approximately 0.3% of the mRNA in control-transformed cells. Compared to control cells, cells transformed with the antisense pPIG-A vector show reduced synthesis of GPI anchor intermediates catalyzed in their endoplasmic reticula and a very few GPI-anchored proteins among the peripheral proteins that can be recovered from their surfaces. They also show specific defects in chemoresponse to glutamate and folate. Other cellular functions, such as growth and mating, seem to be normal.
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MESH Headings
- Amino Acid Sequence
- Animals
- Blotting, Western
- Chemoreceptor Cells/drug effects
- Chemoreceptor Cells/metabolism
- Cloning, Molecular
- Conserved Sequence
- Gene Expression/drug effects
- Genes, Protozoan
- Glycosylphosphatidylinositols/genetics
- Glycosylphosphatidylinositols/metabolism
- Molecular Sequence Data
- Oligonucleotides, Antisense/pharmacology
- Paramecium tetraurelia/chemistry
- Paramecium tetraurelia/metabolism
- Protein Structure, Tertiary
- Protozoan Proteins/chemistry
- RNA, Antisense/metabolism
- RNA, Messenger/drug effects
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Transformation, Genetic
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Affiliation(s)
- Junji Yano
- Department of Biology, University of Vermont, Burlington, Vermont 05405, USA
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Vetter D, Kissmehl R, Treptau T, Hauser K, Kellermann J, Plattner H. Molecular identification of a calcium-inhibited catalytic subunit of casein kinase type 2 from Paramecium tetraurelia. EUKARYOTIC CELL 2004; 2:1220-33. [PMID: 14665457 PMCID: PMC326640 DOI: 10.1128/ec.2.6.1220-1233.2003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have previously described the occurrence in Paramecium of a casein kinase (CK) activity (EC 2.7.1.37) with some unusual properties, including inhibition by Ca(2+) (R. Kissmehl, T. Treptau, K. Hauser, and H. Plattner, FEBS Lett. 402:227-235, 1995). We now have cloned four genes, PtCK2alpha1 to PtCK2alpha4, all of which encode the catalytic alpha subunit of type 2 CK (CK2) with calculated molecular masses ranging from 38.9 to 39.4 kDa and pI values ranging from 8.8 to 9.0. They can be classified into two groups, which differ from each other by 28% on the nucleotide level and by 18% on the derived amino acid level. One of them, PtCK2alpha3, has been expressed in Escherichia coli and characterized in vitro. As we also have observed with the isolated CK, the recombinant protein preferentially phosphorylates casein but also phosphorylates some Paramecium-specific substrates, including the exocytosis-sensitive phosphoprotein pp63/parafusin. Characteristically, Ca(2+) inhibits the phosphorylation at elevated concentrations occurring during stimulation of a cell. Reconstitution with a recombinant form of the regulatory subunit from Xenopus laevis, XlCK2beta, confirms Ca(2+) sensitivity also under conditions of autophosphorylation. This is unusual for CK2 but correlates with the presence of two EF-hand calcium-binding motifs, one of which is located in the N-terminal segment essential for constitutive activity, as well as with an aberrant composition of normally basic domains recognizing acidic substrate domains. Immunogold localization reveals a considerable enrichment in the outermost cell cortex layers, excluding cilia. We discuss a potential role of this Ca(2+)-inhibited PtCK2alpha species in a late step of signal transduction.
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Affiliation(s)
- Daniel Vetter
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
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11
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Ermilova EV, Zalutskaya ZM, Gromov BV, Häder DP, Purton S. Isolation and characterisation of chemotactic mutants of Chlamydomonas reinhardtii obtained by insertional mutagenesis. Protist 2000; 151:127-37. [PMID: 10965952 DOI: 10.1078/1434-4610-00013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The swimming behaviour of the green flagellated protist Chlamydomonas reinhardtii is influenced by several different external stimuli including light and chemical attractants. Common components are involved in both the photo- and chemo-sensory transduction pathways, although the nature and organisation of these pathways are poorly understood. To learn more about the mechanism of chemotaxis in Chlamydomonas, we have generated nonchemotactic strains by insertional mutagenesis. The arginine-requiring strain arg7-8 was transformed with DNA carrying the wild-type ARG7 gene. Of the 8630 arginine-independenttransformants obtained, five are defective in their chemotaxis towards various sugars. Two of the mutants (CTX2 and CTX3) are blocked only in their response to xylose. Mutant CTX1 is blocked in its response to xylose, maltose and mannitol, but displays normal taxis to sucrose. Mutants CTX4 and CTX5 lack chemotactic responses to all sugars tested. CTX1, CTX4 and CTX5 represent novel chemotactic phenotypes not previously obtained using ultra-violet or chemical mutagenesis. Genetic analysis confirms that each mutation maps to a single nuclear locus that is unlinked to the mating-type locus. Further analysis of CTX4 indicates that the mutant allele is tagged by the transforming ARG7 DNA. CTX4 appears to be defective in a component specific for chemotactic signal transduction since it exhibits wild-type photobehavioural responses (phototaxis and photoshock) as well as the wild-type responses of EGTA-induced trans-flagellum inactivation and acid-induced deflagellation. Insertional mutagenesis has thus permitted the generation of novel chemotactic mutants that will be of value in the molecular dissection of the signalling machinery.
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Affiliation(s)
- E V Ermilova
- Laboratory of Microbiology, Biological Research Institute of St Petersburg University, Russia.
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Davis DP, Fiekers JF, Van Houten JL. Intracellular pH and chemoresponse to NH4+ in Paramecium. CELL MOTILITY AND THE CYTOSKELETON 2000; 40:107-18. [PMID: 9634209 DOI: 10.1002/(sici)1097-0169(1998)40:2<107::aid-cm1>3.0.co;2-c] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Paramecium are attracted to ammonium chloride solutions relative to sodium chloride control solutions, but little is known about the mechanisms by which attraction is evoked. A known effect of ammonium solutions in other cell types is an alteration of intracellular pH. We show here that intracellular pH is elevated upon initial exposure to 5 mM NH4Cl, but appears to decline within 10 minutes, both in wild type cells and in two mutants which do not show sustained attraction to NH4Cl using the standard behavioral assay, the T-maze. We also present quantitative values of swimming parameters that underlie the response to NH4Cl.
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Affiliation(s)
- D P Davis
- Department of Biology, University of Vermont, Burlington 05405-0068, USA
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Abstract
Paramecia are ciliated single-cell eukaryotic organisms that can respond to chemical cues in their environment. Glutamate is among those cues, which attract cells. We describe briefly here the following attributes of glutamate chemoresponse: 1) Cells are attracted to L-glutamate relative to KCl at high concentrations of glutamate. 2) There are at least two specific, relatively low affinity glutamate binding sites on the cell surface. Glutamate can be displaced from only one of the binding sites by inosine monophosphate (IMP), and quisqualate displaces glutamate from the second site, which is likely to be the glutamate receptor involved in attraction to glutamate. 3) IMP is a repellent and does not act synergistically with glutamate, whereas guanosine monophosphate (GMP) does. 4) Similarly, glutathione is an attractant, but glutamate and glutathione appear to use different transduction pathways. 5) Glutamate hyperpolarizes the cell. The ionic mechanism is not yet verified, but is likely to involve a K conductance. 6) Glutamate induces a rapid and robust increase in cAMP in the cell. Protein kinase A (PKA) is possibly involved in the transduction pathway because kinase inhibitors such as H7 and H8 inhibit glutamate response, but do not affect responses to other attractants, such as acetate and ammonium. Activation of PKA by the rapid rise in cAMP may sustain the hyperpolarization phosphorylation and activation of the plasma membrane calcium pump. 7) Candidate glutamate binding proteins are being identified among the cell surface proteins with the use of affinity chromatography.
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Affiliation(s)
- J L Van Houten
- Department of Biology, University of Vermont, Burlington, VT 05405, USA
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Orias E. Mapping the germ-line and somatic genomes of a ciliated protozoan, Tetrahymena thermophila. Genome Res 1998; 8:91-9. [PMID: 9477337 DOI: 10.1101/gr.8.2.91] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ciliates are among the very few eukaryotes in which the powers of molecular biology, conventional genetics, and microbial methodology can be synergistically combined. Because ciliates also are distant relatives of vertebrates, fungi, and plants, the sequencing of a ciliate genome will be of import to our understanding of eukaryotic biology. Tetrahymena thermophila is the only ciliate in which a systematic genetic mapping of DNA polymorphisms has begun. Tetrahymena has many biological features that make it a specially or uniquely useful experimental system for fundamental research in cell and molecular biology and for biotechnological applications. A key factor in the usefulness of Tetrahymena is the speed, facility, and versatility with which it can be cultivated under a wide range of nutrient conditions, temperature, and scale. This article describes the progress made in genetically and physically mapping the genomes of T. thermophila: the micronuclear (germ-line) genome, which is not transcriptionally expressed, and the macronuclear (somatic) fragmented genome, which is actively expressed and determines the cell's phenotype.
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Affiliation(s)
- E Orias
- Department of Molecular, Cellular, and Developmental Biology, University of California at Santa Barbara (UCSB), Santa Barbara, California 93106, USA.
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16
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Kim MY, Kuruvilla HG, Hennessey TM. Chemosensory adaptation in paramecium involves changes in both repellent binding and the consequent receptor potentials. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s0300-9629(96)00467-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Elwess NL, Van Houten JL. Cloning and molecular analysis of the plasma membrane Ca(2+)-ATPase gene in Paramecium tetraurelia. J Eukaryot Microbiol 1997; 44:250-7. [PMID: 9183714 DOI: 10.1111/j.1550-7408.1997.tb05708.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have determined the DNA sequence of the gene encoding the protein of the plasma membrane Ca(2+)-ATPase in Paramecium tetraurelia. The predicted amino acid sequence of the plasma membrane Ca(2+)-ATPase shows homology to conserved regions of known plasma membrane Ca(2+)-ATPases and contains the known binding sites for ATP (FITC), acylphosphate formation, and calmodulin, as well as the "hinge" region: all characteristics common to plasma membrane Ca(2+)-ATPases. The deduced molecular weight for this sequence is 131 kDa. The elucidation of this gene will assist in the studies of the mechanisms by which this excitable cell removes calcium entering through voltage gated calcium channels and the pump functions in chemosensory signal transduction.
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Affiliation(s)
- N L Elwess
- Department of Biology, University of Vermont, Burtington 05405, USA
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Kuhlmann HW, Brünen-Nieweler C, Heckmann K. Pheromones of the ciliateEuplotes octocarinatus not only induce conjugation but also function as chemoattractants. ACTA ACUST UNITED AC 1997. [DOI: 10.1002/(sici)1097-010x(19970101)277:1<38::aid-jez4>3.0.co;2-c] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Leick V, Grave M, Hellung-Larsen P. Signal peptide-induced sensory behavior in free ciliates: bioassays and cellular mechanisms. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1996; 17:61-79. [PMID: 8822800 DOI: 10.1007/978-3-642-80106-8_4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- V Leick
- Department of Biochemistry B, University of Copenhagen, Denmark
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Abstract
Increasing evidence indicates that inositol phosphate as well as cyclic nucleotide signalling pathways mediate olfactory transduction. Both pathways can target multiple ion channel effectors, suggesting that olfactory receptor cells serve as more than simple selectivity filters and that they possibly represent the first stage of olfactory integration.
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Affiliation(s)
- B W Ache
- Whitney Laboratory, University of Florida 32086, USA
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