scholarly journals A novel mechanism for chemosensory transduction in insects

Channels ◽  
2008 ◽  
Vol 2 (3) ◽  
pp. 158-158
Author(s):  
Andrew P. Braun
Keyword(s):  
Chemosensory Transduction

scholarly journals The Na+/Ca2+ Exchanger Inhibitor, KB-R7943, Blocks a Nonselective Cation Channel Implicated in Chemosensory Transduction

2009 ◽  
Vol 101 (3) ◽  
pp. 1151-1159 ◽  
Author(s):  
A. Pezier ◽  
Y. V. Bobkov ◽  
B. W. Ache
Keyword(s):  
Transient Receptor Potential ◽  
Single Channel ◽  
Receptor Potential ◽  
Trpc Channels ◽  
Dependent Manner ◽  
Open Probability ◽  
Olfactory Transduction ◽  
Voltage Dependent ◽  
Chemosensory Transduction ◽  
Transient Receptor

The mechanism(s) of olfactory transduction in invertebrates remains to be fully understood. In lobster olfactory receptor neurons (ORNs), a nonselective sodium-gated cation (SGC) channel, a presumptive transient receptor potential (TRP)C channel homolog, plays a crucial role in olfactory transduction, at least in part by amplifying the primary transduction current. To better determine the functional role of the channel, it is important to selectively block the channel independently of other elements of the transduction cascade, causing us to search for specific pharmacological blockers of the SGC channel. Given evidence that the Na+/Ca2+ exchange inhibitor, KB-R7943, blocks mammalian TRPC channels, we studied this probe as a potential blocker of the lobster SGC channel. KB-R7943 reversibly blocked the SGC current in both inside- and outside-out patch recordings in a dose- and voltage-dependent manner. KB-R7943 decreased the channel open probability without changing single channel amplitude. KB-R7943 also reversibly and in a dose-dependent manner inhibited both the odorant-evoked discharge of lobster ORNs and the odorant-evoked whole cell current. Our findings strongly imply that KB-R7943 potently blocks the lobster SGC channel and likely does so directly and not through its ability to block the Na+/Ca2+ exchanger.

scholarly journals Genetic analysis of chemosensory control of dauer formation in Caenorhabditis elegans.

Genetics ◽  
1992 ◽  
Vol 130 (1) ◽  
pp. 105-123 ◽  
Author(s):  
J J Vowels ◽  
J H Thomas
Keyword(s):  
Caenorhabditis Elegans ◽  
Genetic Analysis ◽  
Single Step ◽  
Genetic Interactions ◽  
The Other ◽  
Environmental Cues ◽  
Dauer Larva ◽  
Chemosensory Transduction ◽  
Dauer Formation ◽  
Dauer Larvae

Abstract Dauer larva formation in Caenorhabditis elegans is controlled by chemosensory cells that respond to environmental cues. Genetic interactions among mutations in 23 genes that affect dauer larva formation were investigated. Mutations in seven genes that cause constitutive dauer formation, and mutations in 16 genes that either block dauer formation or result in the formation of abnormal dauers, were analyzed. Double mutants between dauer-constitutive and dauer-defective mutations were constructed and characterized for their capacity to form dauer larvae. Many of the genes could be interpreted to lie in a simple linear epistasis pathway. Three genes, daf-16, daf-18 and daf-20, may affect downstream steps in a branched part of the pathway. Three other genes, daf-2, daf-3 and daf-5, displayed partial or complex epistasis interactions that were difficult to interpret as part of a simple linear pathway. Dauer-defective mutations in nine genes cause structurally defective chemosensory cilia, thereby blocking chemosensation. Mutations in all nine of these genes appear to fall at a single step in the epistasis pathway. Dauer-constitutive mutations in one gene, daf-11, were strongly suppressed for dauer formation by mutations in the nine cilium-structure genes. Mutations in the other six dauer-constitutive genes caused dauer formation despite the absence of functional chemosensory endings. These results suggest that daf-11 is directly involved in chemosensory transduction essential for dauer formation, while the other Daf-c genes play roles downstream of the chemosensory step.

scholarly journals Ion Conductances in Supporting Cells Isolated From the Mouse Vomeronasal Organ

2003 ◽  
Vol 89 (1) ◽  
pp. 118-127 ◽  
Author(s):  
Valeria Ghiaroni ◽  
Francesca Fieni ◽  
Roberto Tirindelli ◽  
Pierangelo Pietra ◽  
Albertino Bigiani
Keyword(s):  
Vomeronasal Organ ◽  
Sensory Epithelium ◽  
Resting Potential ◽  
Patch Clamp Recording ◽  
Supporting Cells ◽  
Electrophysiological Properties ◽  
Voltage Dependent ◽  
Typical Morphology ◽  
Chemosensory Transduction ◽  
Ion Conductances

The vomeronasal organ (VNO) is a chemosensory structure involved in the detection of pheromones in most mammals. The VNO sensory epithelium contains both neurons and supporting cells. Data suggest that vomeronasal neurons represent the pheromonal transduction sites, whereas scarce information is available on the functional properties of supporting cells. To begin to understand their role in VNO physiology, we have characterized with patch-clamp recording techniques the electrophysiological properties of supporting cells isolated from the neuroepithelium of the mouse VNO. Supporting cells were distinguished from neurons by their typical morphology and by the lack of immunoreactivity for Gγ8 and OMP, two specific markers for vomeronasal neurons. Unlike glial cells in other tissues, VNO supporting cells exhibited a depolarized resting potential (about −29 mV). A Goldman-Hodgkin-Katz analysis for resting ion permeabilities revealed indeed an unique ratio of P K: P Na: P Cl= 1:0.23:1.4. Supporting cells also possessed voltage-dependent K+ and Na+ conductances that differed significantly in their biophysical and pharmacological properties from those expressed by VNO neurons. Thus glial membranes in the VNO can sustain significant fluxes of K+ and Na+, as well as Cl−. This functional property might allow supporting cells to mop-up and redistribute the excess of KCl and NaCl that often occurs in certain pheromone-delivering fluids, like urine, and that could blunt the sensitivity of VNO neurons to pheromones. Therefore vomeronasal supporting cells could affect chemosensory transduction in the VNO by regulating the ionic strength of the pheromone-containing medium.

ATP is a key mediator of central and peripheral chemosensory transduction

2003 ◽  
Vol 89 (1) ◽  
pp. 53-59 ◽  
Author(s):  
K. Michael Spyer ◽  
Nicholas Dale ◽  
Alexander V. Gourine
Keyword(s):  
Chemosensory Transduction

A Transmembrane Guanylyl Cyclase (DAF-11) and Hsp90 (DAF-21) Regulate a Common Set of Chemosensory Behaviors in Caenorhabditis elegans

Genetics ◽  
2000 ◽  
Vol 155 (1) ◽  
pp. 85-104 ◽  
Author(s):  
Deborah A Birnby ◽  
Elizabeth Malone Link ◽  
Jennifer J Vowels ◽  
Hong Tian ◽  
Patrick L Colacurcio ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Guanylyl Cyclase ◽  
Large Family ◽  
Heat Shock Protein 90 ◽  
Specific Protein ◽  
Single Amino Acid ◽  
C Elegans ◽  
Chemosensory Transduction ◽  
Chemosensory Pathways ◽  
Mutant Phenotypes

Abstract Caenorhabditis elegans daf-11 and daf-21 mutants share defects in specific chemosensory responses mediated by several classes of sensory neurons, indicating that these two genes have closely related functions in an assortment of chemosensory pathways. We report that daf-11 encodes one of a large family of C. elegans transmembrane guanylyl cyclases (TM-GCs). The cyclic GMP analogue 8-bromo-cGMP rescues a sensory defect in both daf-11 and daf-21 mutants, supporting a role for DAF-11 guanylyl cyclase activity in this process and further suggesting that daf-21 acts at a similar step. daf-11::gfp fusions are expressed in five identified pairs of chemosensory neurons in a pattern consistent with most daf-11 mutant phenotypes. We also show that daf-21 encodes the heat-shock protein 90 (Hsp90), a chaperone with numerous specific protein targets. We show that the viable chemosensory-deficient daf-21 mutation is an unusual allele resulting from a single amino acid substitution and that the daf-21 null phenotype is early larval lethality. These results demonstrate that cGMP is a prominent second messenger in C. elegans chemosensory transduction and suggest a previously unknown role for Hsp90 in regulating cGMP levels.

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