The phototransduction machinery in the rod outer segment has a strong efficacy gradient
Type
ArticleAuthors
Mazzolini, MonicaFacchetti, Giuseppe
Andolfi, Laura
Zaccaria, Remo Proietti
Tuccio, Salvatore
Treud, Johannes
Altafini, Claudio
Di Fabrizio, Enzo M.

Lazzarino, Marco
Rapp, Gert
Torre, Vincent
KAUST Department
Material Science and Engineering ProgramPhysical Science and Engineering (PSE) Division
Date
2015-05-04Online Publication Date
2015-05-04Print Publication Date
2015-05-19Permanent link to this record
http://hdl.handle.net/10754/564170
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Show full item recordAbstract
Rod 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.Sponsors
We 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 ID
25941368PubMed Central ID
PMC4443333Additional Links
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4443333ae974a485f413a2113503eed53cd6c53
10.1073/pnas.1423162112
Scopus Count
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