The phototransduction machinery in the rod outer segment has a strong efficacy gradient
Zaccaria, Remo Proietti
Di Fabrizio, Enzo M.
KAUST DepartmentMaterial Science and Engineering Program
Physical Science and Engineering (PSE) Division
Online Publication Date2015-05-04
Print Publication Date2015-05-19
Permanent link to this recordhttp://hdl.handle.net/10754/564170
MetadataShow full item record
AbstractRod photoreceptors consist of an outer segment (OS) and an inner segment. Inside the OS a biochemical machinery transforms the rhodopsin photoisomerization into electrical signal. This machinery has been treated as and is thought to be homogenous with marginal inhomogeneities. To verify this assumption, we developed a methodology based on special tapered optical fibers (TOFs) to deliver highly localized light stimulations. By using these TOFs, specific regions of the rod OS could be stimulated with spots of light highly confined in space. As the TOF is moved from the OS base toward its tip, the amplitude of saturating and single photon responses decreases, demonstrating that the efficacy of the transduction machinery is not uniform and is 5-10 times higher at the base than at the tip. This gradient of efficacy of the transduction machinery is attributed to a progressive depletion of the phosphodiesterase along the rod OS. Moreover we demonstrate that, using restricted spots of light, the duration of the photoresponse along the OS does not increase linearly with the light intensity as with diffuse light. © 2015, National Academy of Sciences. All rights reserved.
SponsorsWe thank Profs. Trevor Lamb and Fabio Benfenati for reading the manuscript, M. Lough for checking the English, and Paolo Fabris for MatLab support. This work was supported by FOCUS Contract 270483 (FP7-ICT-2009-6) from the European Union.
PubMed Central IDPMC4443333
- Phototransduction and calcium exchange along the length of the retinal rod outer segment.
- Authors: Leibovic KN, Bandarchi J
- Issue date: 1997 Mar 24
- Toward a unified model of vertebrate rod phototransduction.
- Authors: Hamer RD, Nicholas SC, Tranchina D, Lamb TD, Jarvinen JL
- Issue date: 2005 Jul-Aug
- On the activation of phosphodiesterase by a 26 kDa protein.
- Authors: Nikonov SS, Filatov GN, Fesenko EE
- Issue date: 1993 Jan 18
- In vivo optophysiology reveals that G-protein activation triggers osmotic swelling and increased light scattering of rod photoreceptors.
- Authors: Zhang P, Zawadzki RJ, Goswami M, Nguyen PT, Yarov-Yarovoy V, Burns ME, Pugh EN Jr
- Issue date: 2017 Apr 4
- cGMP suppresses GTPase activity of a portion of transducin equimolar to phosphodiesterase in frog rod outer segments. Light-induced cGMP decreases as a putative feedback mechanism of the photoresponse.
- Authors: Arshavsky VYu, Gray-Keller MP, Bownds MD
- Issue date: 1991 Oct 5