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Valentine M, Yano J, Lodh S, Nabi A, Deng B, Van Houten J. Methods for Paramecium tetraurelia ciliary membrane protein identification and function. Methods Cell Biol 2023; 175:177-219. [PMID: 36967141 DOI: 10.1016/bs.mcb.2022.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
In this chapter we provide some tools to study the ciliary proteins that make it possible for Paramecium cells to swim by beating their cilia. These proteins include many ion channels, accessory proteins, peripheral proteins, structural proteins, rootlets of cilia, and enzymes. Some of these proteins are also found in the soma membrane, but their distinct and critical functions are in the cilia. Paramecium has 4000 or more cilia per cell, giving it an advantage for biochemical studies over cells that have one primarily cilium per cell. Nonetheless, a challenge for studies of many ciliary proteins in Paramecium is their low abundance. We discuss here several strategies to overcome this challenge and other challenges such as working with very large channel proteins. We also include for completeness other techniques that are critical to the study of swimming behavior, such as genetic crosses, recording of swimming patterns, electrical recordings, expression of very large channel proteins, RNA Interference, among others.
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Affiliation(s)
- Megan Valentine
- State University of New York, Plattsburgh, NY, United States
| | - Junji Yano
- University of Vermont, Burlington, VT, United States
| | - Sukanya Lodh
- Marquette University, Milwaukee, WI, United States
| | | | - Bin Deng
- Vermont Biomedical Research Network, University of Vermont, Burlington, VT, United States
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2
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Nguyen TD, Truong ME, Reiter JF. The Intimate Connection Between Lipids and Hedgehog Signaling. Front Cell Dev Biol 2022; 10:876815. [PMID: 35757007 PMCID: PMC9222137 DOI: 10.3389/fcell.2022.876815] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 05/13/2022] [Indexed: 01/19/2023] Open
Abstract
Hedgehog (HH) signaling is an intercellular communication pathway involved in directing the development and homeostasis of metazoans. HH signaling depends on lipids that covalently modify HH proteins and participate in signal transduction downstream. In many animals, the HH pathway requires the primary cilium, an organelle with a specialized protein and lipid composition. Here, we review the intimate connection between HH signaling and lipids. We highlight how lipids in the primary cilium can create a specialized microenvironment to facilitate signaling, and how HH and components of the HH signal transduction pathway use lipids to communicate between cells.
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Affiliation(s)
- Thi D. Nguyen
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States
| | - Melissa E. Truong
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Jeremy F. Reiter
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States,Chan Zuckerberg Biohub, San Francisco, CA, United States,*Correspondence: Jeremy F. Reiter,
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Abstract
K+ channels enable potassium to flow across the membrane with great selectivity. There are four K+ channel families: voltage-gated K (Kv), calcium-activated (KCa), inwardly rectifying K (Kir), and two-pore domain potassium (K2P) channels. All four K+ channels are formed by subunits assembling into a classic tetrameric (4x1P = 4P for the Kv, KCa, and Kir channels) or tetramer-like (2x2P = 4P for the K2P channels) architecture. These subunits can either be the same (homomers) or different (heteromers), conferring great diversity to these channels. They share a highly conserved selectivity filter within the pore but show different gating mechanisms adapted for their function. K+ channels play essential roles in controlling neuronal excitability by shaping action potentials, influencing the resting membrane potential, and responding to diverse physicochemical stimuli, such as a voltage change (Kv), intracellular calcium oscillations (KCa), cellular mediators (Kir), or temperature (K2P).
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Cid NG, Puca G, Nudel CB, Nusblat AD. Genome analysis of sphingolipid metabolism-related genes in Tetrahymena thermophila and identification of a fatty acid 2-hydroxylase involved in the sexual stage of conjugation. Mol Microbiol 2020; 114:775-788. [PMID: 32713049 DOI: 10.1111/mmi.14578] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 07/15/2020] [Accepted: 07/16/2020] [Indexed: 11/29/2022]
Abstract
Sphingolipids are bioactive lipids present in all eukaryotes. Tetrahymena thermophila is a ciliate that displays remarkable sphingolipid moieties, that is, the unusual phosphonate-linked headgroup ceramides, present in membranes. To date, no identification has been made in this organism of the functions or related genes implicated in sphingolipid metabolism. By gathering information from the T. thermophila genome database together with sphingolipid moieties and enzymatic activities reported in other Tetrahymena species, we were able to reconstruct the putative de novo sphingolipid metabolic pathway in T. thermophila. Orthologous genes of 11 enzymatic steps involved in the biosynthesis and degradation pathways were retrieved. No genes related to glycosphingolipid or phosphonosphingolipid headgroup transfer were found, suggesting that both conserved and innovative mechanisms are used in ciliate. The knockout of gene TTHERM_00463850 allowed to identify the gene encoding a putative fatty acid 2-hydroxylase, which is involved in the biosynthesis pathway. Knockout cells have shown several impairments in the sexual stage of conjugation since different mating types of knockout strains failed to form cell pairs and complete the conjugation process. This fatty acid 2-hydroxylase gene is the first gene of a sphingolipid metabolic pathway to be identified in ciliates and have a critical role in their sexual stage.
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Affiliation(s)
- Nicolas G Cid
- Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Nanobiotecnología (NANOBIOTEC), Buenos Aires, Argentina
| | - Gervasio Puca
- Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Nanobiotecnología (NANOBIOTEC), Buenos Aires, Argentina
| | - Clara B Nudel
- Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Nanobiotecnología (NANOBIOTEC), Buenos Aires, Argentina
| | - Alejandro D Nusblat
- Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Nanobiotecnología (NANOBIOTEC), Buenos Aires, Argentina
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Garcia-Gonzalo FR, Phua SC, Roberson EC, Garcia G, Abedin M, Schurmans S, Inoue T, Reiter JF. Phosphoinositides Regulate Ciliary Protein Trafficking to Modulate Hedgehog Signaling. Dev Cell 2015; 34:400-409. [PMID: 26305592 DOI: 10.1016/j.devcel.2015.08.001] [Citation(s) in RCA: 223] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 08/01/2015] [Accepted: 08/05/2015] [Indexed: 12/17/2022]
Abstract
Primary cilia interpret vertebrate Hedgehog (Hh) signals. Why cilia are essential for signaling is unclear. One possibility is that some forms of signaling require a distinct membrane lipid composition, found at cilia. We found that the ciliary membrane contains a particular phosphoinositide, PI(4)P, whereas a different phosphoinositide, PI(4,5)P2, is restricted to the membrane of the ciliary base. This distribution is created by Inpp5e, a ciliary phosphoinositide 5-phosphatase. Without Inpp5e, ciliary PI(4,5)P2 levels are elevated and Hh signaling is disrupted. Inpp5e limits the ciliary levels of inhibitors of Hh signaling, including Gpr161 and the PI(4,5)P2-binding protein Tulp3. Increasing ciliary PI(4,5)P2 levels or conferring the ability to bind PI(4)P on Tulp3 increases the ciliary localization of Tulp3. Lowering Tulp3 in cells lacking Inpp5e reduces ciliary Gpr161 levels and restores Hh signaling. Therefore, Inpp5e regulates ciliary membrane phosphoinositide composition, and Tulp3 reads out ciliary phosphoinositides to control ciliary protein localization, enabling Hh signaling.
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Affiliation(s)
- Francesc R Garcia-Gonzalo
- Department of Biochemistry and Biophysics and Cardiovascular Research Institute, University of California, San Francisco (UCSF), San Francisco, CA 94158, USA
| | - Siew C Phua
- Department of Cell Biology and Center for Cell Dynamics, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
| | - Elle C Roberson
- Department of Biochemistry and Biophysics and Cardiovascular Research Institute, University of California, San Francisco (UCSF), San Francisco, CA 94158, USA
| | - Galo Garcia
- Department of Biochemistry and Biophysics and Cardiovascular Research Institute, University of California, San Francisco (UCSF), San Francisco, CA 94158, USA
| | - Monika Abedin
- Department of Biochemistry and Biophysics and Cardiovascular Research Institute, University of California, San Francisco (UCSF), San Francisco, CA 94158, USA
| | - Stéphane Schurmans
- Laboratory of Functional Genetics, GIGA-Research Centre, Université de Liège, 4000-Liège, Belgium
| | - Takanari Inoue
- Department of Cell Biology and Center for Cell Dynamics, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
| | - Jeremy F Reiter
- Department of Biochemistry and Biophysics and Cardiovascular Research Institute, University of California, San Francisco (UCSF), San Francisco, CA 94158, USA
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Nguyen PAT, Liou W, Hall DH, Leroux MR. Ciliopathy proteins establish a bipartite signaling compartment in a C. elegans thermosensory neuron. J Cell Sci 2014; 127:5317-30. [PMID: 25335890 DOI: 10.1242/jcs.157610] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
How signaling domains form is an important, yet largely unexplored question. Here, we show that ciliary proteins help establish two contiguous, yet distinct cyclic GMP (cGMP) signaling compartments in Caenorhabditis elegans thermosensory AFD neurons. One compartment, a bona fide cilium, is delineated by proteins associated with Bardet-Biedl syndrome (BBS), Meckel syndrome and nephronophthisis at its base, and requires NPHP-2 (known as inversin in mammals) to anchor a cGMP-gated ion channel within the proximal ciliary region. The other, a subcompartment with profuse microvilli and a different lipid environment, is separated from the dendrite by a cellular junction and requires BBS-8 and DAF-25 (known as Ankmy2 in mammals) for correct localization of guanylyl cyclases needed for thermosensation. Consistent with a requirement for a membrane diffusion barrier at the subcompartment base, we reveal the unexpected presence of ciliary transition zone proteins where no canonical transition zone ultrastructure exists. We propose that differential compartmentalization of signal transduction components by ciliary proteins is important for the functions of ciliated sensory neurons.
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Affiliation(s)
- Phuong Anh T Nguyen
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Willisa Liou
- Department of Anatomy, Chang Gung University, Kwei-san Tao-yuan 333, Taiwan
| | - David H Hall
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Michel R Leroux
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
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Syeda R, Santos JS, Montal M. Lipid bilayer modules as determinants of K+ channel gating. J Biol Chem 2013; 289:4233-43. [PMID: 24362039 DOI: 10.1074/jbc.m113.530055] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The crystal structure of the sensorless pore module of a voltage-gated K(+) (Kv) channel showed that lipids occupy a crevice between subunits. We asked if individual lipid monolayers of the bilayer embody independent modules linked to channel gating modulation. Functional studies using single channel current recordings of the sensorless pore module reconstituted in symmetric and asymmetric lipid bilayers allowed us to establish the deterministic role of lipid headgroup on gating. We discovered that individual monolayers with headgroups that coat the bilayer-aqueous interface with hydroxyls stabilize the channel open conformation. The hydroxyl need not be at a terminal position and the effect is not dependent on the presence of phosphate or net charge on the lipid headgroup. Asymmetric lipid bilayers allowed us to determine that phosphoglycerides with glycerol or inositol on the extracellular facing monolayer stabilize the open conformation of the channel. This indirect effect is attributed to a change in water structure at the membrane interface. By contrast, inclusion of the positively charged lysyl-dioleoyl-phosphatidylglycerol exclusively on the cytoplasmic facing monolayer of the bilayer increases drastically the probability of finding the channel open. Such modulation is mediated by a π-cation interaction between Phe-19 of the pore module and the lysyl moiety anchored to the phosphatidylglycerol headgroup. The new findings imply that the specific chemistry of the lipid headgroup and its selective location in either monolayer of the bilayer dictate the stability of the open conformation of a Kv pore module in the absence of voltage-sensing modules.
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Affiliation(s)
- Ruhma Syeda
- From the Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, California 92093
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Abstract
Rising atmospheric carbon dioxide (CO2) conditions are driving unprecedented changes in seawater chemistry, resulting in reduced pH and carbonate ion concentrations in the Earth's oceans. This ocean acidification has negative but variable impacts on individual performance in many marine species. However, little is known about the adaptive capacity of species to respond to an acidified ocean, and, as a result, predictions regarding future ecosystem responses remain incomplete. Here we demonstrate that ocean acidification generates striking patterns of genome-wide selection in purple sea urchins (Strongylocentrotus purpuratus) cultured under different CO2 levels. We examined genetic change at 19,493 loci in larvae from seven adult populations cultured under realistic future CO2 levels. Although larval development and morphology showed little response to elevated CO2, we found substantial allelic change in 40 functional classes of proteins involving hundreds of loci. Pronounced genetic changes, including excess amino acid replacements, were detected in all populations and occurred in genes for biomineralization, lipid metabolism, and ion homeostasis--gene classes that build skeletons and interact in pH regulation. Such genetic change represents a neglected and important impact of ocean acidification that may influence populations that show few outward signs of response to acidification. Our results demonstrate the capacity for rapid evolution in the face of ocean acidification and show that standing genetic variation could be a reservoir of resilience to climate change in this coastal upwelling ecosystem. However, effective response to strong natural selection demands large population sizes and may be limited in species impacted by other environmental stressors.
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Konno A, Setou M, Ikegami K. Ciliary and flagellar structure and function--their regulations by posttranslational modifications of axonemal tubulin. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 294:133-70. [PMID: 22364873 DOI: 10.1016/b978-0-12-394305-7.00003-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Eukaryotic cilia and flagella are evolutionarily conserved microtubule-based organelles protruding from the cell surface. They perform dynein-driven beating which contributes to cell locomotion or flow generation. They also play important roles in sensing as cellular antennae, which allows cells to respond to various external stimuli. The main components of cilia and flagella, α- and β-tubulins, are known to undergo various posttranslational modifications (PTMs), including phosphorylation, palmitoylation, tyrosination/detyrosination, Δ2 modification, acetylation, glutamylation, and glycylation. Recent identification of tubulin-modifying enzymes, especially tubulin tyrosine ligase-like proteins which perform tubulin glutamylation and glycylation, has demonstrated the importance of tubulin modifications for the assembly and functions of cilia and flagella. In this chapter, we review recent work on PTMs of ciliary and flagellar tubulins in conjunction with discussing the basic knowledge.
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Affiliation(s)
- Alu Konno
- Department of Cell Biology and Anatomy, Hamamatsu University School of Medicine, Hamamatsu, Japan
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Ramoino P, Dini F, Bianchini P, Diaspro A, Guella G, Usai C. Biophysical effects of the natural product euplotin C on the Paramecium membrane. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2009; 195:1061-9. [DOI: 10.1007/s00359-009-0479-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Revised: 09/05/2009] [Accepted: 09/07/2009] [Indexed: 01/13/2023]
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Iwamoto M, Allen RD. Uptake and rapid transfer of fluorescent ceramide analogues to acidosomes (late endosomes) in Paramecium. J Histochem Cytochem 2004; 52:557-65. [PMID: 15100234 DOI: 10.1177/002215540405200501] [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] [Indexed: 11/17/2022] Open
Abstract
The ciliated protozoan Paramecium incorporates sphingolipids into its cell membranes. However, it is still unclear if these sphingolipids are metabolically synthesized in the cell or if their precursors are taken up from exogenous materials. Here we studied the route of uptake of fluorescence-labeled analogues of ceramide. Fluorescent ceramide was taken up rapidly independent of phagosome formation. Cold treatment caused a decrease in uptake, while reduction in the amount of cytosolic ATP induced by NaN(3) and deoxyglucose resulted in accumulation without internalization of fluorescence at the plasma membrane. These results suggest that uptake of fluorescent ceramide occurs at the plasma membrane, that it is an ATP-dependent process, and that it is not a result of simple diffusion. At first intracellular fluorescence appeared principally in the posterior half of the cell and then spread throughout the cytosol. In particular, a high accumulation of fluorescence occurred in association with acidosomes (late endosome or multivesicular body-like vesicles) that bind to the surface of nascent and young phagosomes. Therefore, in the Paramecium cell a significant proportion of ceramide apparently enters the cell by endocytosis and is quickly relayed to acidosomes along the endocytic pathway before becoming part of the digestive vacuole (phagoacidosome) membrane.
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Affiliation(s)
- Masaaki Iwamoto
- Pacific Biomedical Research Center, University of Hawaii at Manoa, Honolulu 96822, USA
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12
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Tsao JW, Paramananthan N, Parkes HG, Dunn JF. Altered brain metabolism in the C57BL/Wld mouse strain detected by magnetic resonance spectroscopy: association with delayed Wallerian degeneration? J Neurol Sci 1999; 168:1-12. [PMID: 10500267 DOI: 10.1016/s0022-510x(99)00161-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In the C57BL/Wld(s) (Wld) mouse strain, both PNS and CNS axonal disintegration during Wallerian degeneration is dramatically slowed, with isolated axons being able to conduct compound action potentials (CAPs) for several weeks post-transection. The ability to conduct a CAP signifies the presence of an intact plasma membrane, normal ion gradients, and functioning ion channels. In neurons, ion homeostasis is primarily regulated by the Na(+)-K(+)-ATPase, which utilizes approximately 50% of neuronal energy output. To investigate the possibility that the Wld mutation prolongs axonal degeneration by conferring a more favorable energetic status to neurons or alters metabolism, we used 31P and 1H magnetic resonance spectroscopy (MRS) to compare the cerebral and muscle energy metabolism, membrane phospholipid contents, and water-soluble metabolites of Wld and wild-type (C57BL/6J [6J], and BALB/c) mouse strains. We first demonstrate that, with advancing age, transected Wld CNS nerves degenerate faster, paralleling previous findings in the PNS. We found significantly decreased phosphocreatine and phosphomonoester concentrations in the brains of Wld mice at 1- and 2-months of age compared to both 6J and BALB/c mice, but we failed to find differences in the adenylate (ATP, ADP, or AMP) or phospholipid concentrations. In another excitable tissue, skeletal muscle, no differences in energy-containing metabolites were detected. High resolution 1H MRS indicated that at 1 month of age, Wld brains have cytosolic levels of glutamate and phosphocholine that are significantly decreased, relative to total N-acetyl aspartate content. Our results demonstrate that delayed Wallerian degeneration in the C57BL/Wld mouse strain is associated with altered cerebral metabolism, although these changes may be secondary to the mutation.
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Affiliation(s)
- J W Tsao
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, UK.
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13
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Matesic DF, Erwin JA, Kaneshiro ES. Incorporation In Vivo and In Vitro of Radiolabeled Sphingolipid Precursors into Paramecium tetraurelia Lipids. J Eukaryot Microbiol 1998. [DOI: 10.1111/j.1550-7408.1998.tb05084.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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14
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Identification and initial characterizations of free, glycosylated, and phosphorylated ceramides of Paramecium. J Lipid Res 1997. [DOI: 10.1016/s0022-2275(20)30025-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Hinrichsen RD, Fraga D, Russell C. The regulation of calcium in Paramecium. ADVANCES IN SECOND MESSENGER AND PHOSPHOPROTEIN RESEARCH 1995; 30:311-38. [PMID: 7695996 DOI: 10.1016/s1040-7952(05)80013-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- R D Hinrichsen
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98104
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16
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Bregestovski PD, Bolotina VM, Serebryakov VN. Fatty acid modifies Ca2+-dependent potassium channel activity in smooth muscle cells from the human aorta. PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON. SERIES B, BIOLOGICAL SCIENCES 1989; 237:259-66. [PMID: 2571153 DOI: 10.1098/rspb.1989.0048] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
By using the patch-clamp technique the effect of 2-decenoic acid (DA) on Ca2+-activated potassium (K+) channels in the membrane of smooth muscle cells from the human aorta was studied. In the presence of 0.5 microM Ca2+ and 2 mM Mg2+ on the cytoplasmic side of the membrane, a more than tenfold elevation in the probability of the channels being open (po) was observed under the effect of DA. With divalent cation concentrations of less than 1 nM DA caused a more than twofold elevation in po. In the DA-treated membranes Mg2+ ions, which normally fail to activate the channels, brought about a nearly threefold increase in the channel activity when applied to the inner membrane surface. Channel sensitivity to the activating effect of cytoplasmic Ca2+ ions did not increase with the application of DA. Single-channel conductance was unchanged by DA exposure. We suggest that DA alters the Ca2+-binding mechanism of the channel, increasing its sensitivity to Mg2+ ions, presumably owing to membrane fluidization.
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Affiliation(s)
- P D Bregestovski
- Institute of Experimental Cardiology, Academy of Medical Sciences, Moscow, U.S.S.R
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18
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Enright WJ, Hennessey TM. Growth of Paramecium tetraurelia in bacterized, monoxenic cultures. THE JOURNAL OF PROTOZOOLOGY 1987; 34:137-42. [PMID: 3585813 DOI: 10.1111/j.1550-7408.1987.tb03149.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Wild type and mutant Paramecium tetraurelia were grown in monoxenic cultures by first growing Enterobacter aerogenes on a defined medium and then adding the Paramecium to the stationary phase bacterial culture. The bacterial growth was proportional to the concentration of the carbon source (citrate), and the Paramecium growth was dependent upon both the bacterial density and the starting density of Paramecium. The behavior, electrophysiological properties, ciliary lipid composition, and growth characteristics were similar to the commonly used bacterized medium (Cerophyl) except that 5-10 times greater Paramecium yields were reliably obtained.
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Forte M, Hennessey T, Kung C. Mutations resulting in resistance to polyene antibiotics decrease voltage-sensitive calcium channel activity in Paramecium. J Neurogenet 1986; 3:75-85. [PMID: 2420954 DOI: 10.3109/01677068609106896] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In this report, the isolation of Paramecium tetraurelia mutants resistant to the polyene antibiotics amphotericin B and filipin are described. These antibiotics are known to specifically interact with membrane sterols to produce a cytotoxic effect. Four mutants resistant to amphotericin B and two mutants resistant to filipin have been isolated. In each case, an individual mutant shows resistance to both amphotericin B and filipin. Genetic analysis indicates that all 6 mutations map to the same complementation group and are not allelic to any of the 3 pawn mutations or to either of the two "barium shy" mutations. The behavioral analysis suggests that these mutations cause an alteration of normal ion channel function. Direct electrophysiological analysis of one mutant indicates mutations to polyene antibiotic resistance cause a specific decrease in voltage-sensitive Ca2+ channel activity.
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20
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Love JA, Saum WR, McGee R. The effects of exposure to exogenous fatty acids and membrane fatty acid modification on the electrical properties of NG108-15 cells. Cell Mol Neurobiol 1985; 5:333-52. [PMID: 2417716 DOI: 10.1007/bf00755400] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The role of membrane lipid composition in determining the electrical properties of neuronal cells was investigated by altering the available fatty acids in the growth medium of cultured neuroblastoma X glioma hybrid cells, clone NG108-15. Growth of the cells for several days in the presence of polyunsaturated fatty acids (linoleic, linolenic, and arachidonic) caused a pronounced decrease in the Na+ action-potential rate of rise (dV/dt) and smaller decreases in the amplitude, measured by intracellular recording. Oleic acid had no effect on the action potentials generated by the cells. In contrast, a saturated fatty acid (palmitate) and a trans monounsaturated fatty acid (elaidate) caused increases in both the rate of rise and the amplitude. No changes in the resting membrane potentials or Ca2+ action potentials of fatty acid-treated cells were observed. The membrane capacitance and time constant were not altered by exposure to arachidonate, oleate, or elaidate, whereas arachidonate caused a small increase in membrane resistance. Examination of the membrane phospholipid fatty acid composition of cells grown with various fatty acids revealed no consistent alterations which could explain these results. To examine the mechanism for arachidonate-induced decreases in dV/dt, the binding of 3H-saxitoxin (known to interact with voltage-sensitive Na+) channels was measured. Membranes from cells grown with arachidonate contained fewer saxitoxin binding sites, suggesting fewer Na+ channels in these cells. We conclude that conditions which lead to major changes in the membrane fatty acid composition have no effect on the resting membrane potential, membrane capacitance, time constant, or Ca2+ action potentials in NG108-15 cells. Membrane resistance also does not appear to be very sensitive to membrane fatty acid composition. However, changes in the availability of fatty acids and/or changes in the subsequent membrane fatty acid composition lead to altered Na+ action potentials. The primary mechanism for this alteration appears to be through changes in the number of Na+ channels in the cells.
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21
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Hill RJ, Hill M. Variation in the swimming velocity of Tetrahymena thermophila through the cell cycle. Naturwissenschaften 1985. [DOI: 10.1007/bf00410607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Chapter 3 Ca2+ Channels of Paramecium: A Multidisciplinary Study. CURRENT TOPICS IN MEMBRANES AND TRANSPORT 1985. [DOI: 10.1016/s0070-2161(08)60149-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Kaneshiro ES, Matesic DF, Jayasimhulu K. Characterizations of six ethanolamine sphingophospholipids from Paramecium cells and cilia. J Lipid Res 1984. [DOI: 10.1016/s0022-2275(20)37810-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Dantzig AH, Fairgrieve M, Slayman CW, Adelberg EA. Isolation and characterization of a CHO amino acid transport mutant resistant to melphalan (L-phenylalanine mustard). SOMATIC CELL AND MOLECULAR GENETICS 1984; 10:113-21. [PMID: 6584987 DOI: 10.1007/bf01534900] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A mutant of Chinese hamster ovary cells, CHY-2, was isolated on the basis of its reduced ability to grow on a limiting concentration of leucine and was found to be defective in uptake of leucine via the sodium-independent L system. Consistent with published reports that the L system can mediate melphalan uptake, the D10 of the mutant for melphalan was increased threefold under conditions designed to limit drug uptake to the L system (brief exposure in sodium-free medium). Unlike a previously described melphalan-resistant CHO mutant (CHr), CHY-2 displays no cross-resistance to colchicine or puromycin. It differs from a second melphalan-resistant CHO mutant, melr, in its sensitivity to melphalan in the presence of high Na+, and from a melphalan-resistant mouse leukemic cell in possessing normal levels of intracellular glutathione. Thus, CHY-2 represents a new melphalan-resistant mutant class. The effect of the CHY-2 mutation is pleiotropic, involving significant reductions in amino acid uptake via the L, A and Ly+ (but not ASC) systems. The primary defect is unknown; however, the mutant possesses normal intracellular concentrations of Na+ and K+ and normal membrane fluidity. The growth rate of the mutant in standard medium is greatly reduced (generation time of 60 h vs. 24 h), although it can be improved by the addition of a supplement containing high concentrations of leucine, proline, and peptides.
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Ramanathan R, Saimi Y, Peterson JB, Nelson DL, Kung C. Antibodies to the ciliary membrane of Paramecium tetraurelia alter membrane excitability. J Cell Biol 1983; 97:1421-8. [PMID: 6313697 PMCID: PMC2112700 DOI: 10.1083/jcb.97.5.1421] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Immobilization of Paramecium followed the binding of antibodies to the major proteins of the ciliary membrane (the immobilization antigens, i-antigens, approximately 250,000 mol wt). Immunoelectron microscopy showed this binding to be serotype-specific and to occur over the entire cell surface. Antibody binding also reduced the current through the Ca-channel of the excitable ciliary membrane as monitored using a voltage-clamp. The residual Ca-current appeared normal in its voltage sensitivity and kinetics. As a secondary consequence of antibody binding, the Ca-induced K-current was also reduced. The resting membrane characteristics and other activatable currents, however, were not significantly altered by the antibody treatment. Since monovalent fragments of the antibodies also reduced the current but did not immobilize the cell, the electrophysiological effects were not the secondary consequences of immobilization. Antibodies against the second most abundant family of proteins (42,000-45,000 mol wt) had similar electrophysiological effects as revealed by experiments in which the Paramecia and the serum were heterologous with respect to the i-antigen but homologous with respect to the 42,000-45,000-mol-wt proteins. Protease treatment, shown to remove the surface antigen, also caused a reduction of the Ca-inward current. The loss of the inward Ca-current does not seem to be due to a drop in the driving force for Ca++ entry since increasing the external Ca++ or reducing the internal Ca++ (through EGTA injection) did not restore the current. Here we discuss the possibilities that (a) the major proteins define the functional environment of the Ca-channel and that (b) the Ca-channel is more susceptible to certain general changes in the membrane.
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Saimi Y, Hinrichsen RD, Forte M, Kung C. Mutant analysis shows that the Ca2+-induced K+ current shuts off one type of excitation in Paramecium. Proc Natl Acad Sci U S A 1983; 80:5112-6. [PMID: 6410401 PMCID: PMC384199 DOI: 10.1073/pnas.80.16.5112] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Two mutants of Paramecium tetraurelia, called "pantophobiacs," were found to lack most of the slow Ca2+-induced K+ outward current. Passive properties, the transient Ca2+ inward current, and the fast depolarization-induced K+ outward current remain normal. The mutant defect reduces the ability to shut off a normal, excited state of the membrane and results in repeated, long backward swimming instead of the wild-type jerks in response to a variety of ions, to heat, and to touch.
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Hennessey TM, Andrews D, Nelson DL. Biochemical studies of the excitable membrane of Paramecium tetraurelia. VII. Sterols and other neutral lipids of cells and cilia. J Lipid Res 1983. [DOI: 10.1016/s0022-2275(20)37962-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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