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The phototransduction machinery in the rod outer segment has a strong efficacy gradient
International School for Advanced Studies, 34136 Trieste, Italy.
International School for Advanced Studies, 34136 Trieste, Italy.
Cluster for Biomedicine, Trieste.
Istituto Italiano di Tecnologia, 16163 Genova, Italy;.
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2015 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 112, no 20, E2715-E272 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
2015. Vol. 112, no 20, E2715-E272 p.
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:liu:diva-120909DOI: 10.1073/pnas.1423162112PubMedID: 25941368OAI: oai:DiVA.org:liu-120909DiVA: diva2:849577
Available from: 2015-08-28 Created: 2015-08-28 Last updated: 2015-09-17

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Altafini, Claudio
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Automatic ControlFaculty of Science & Engineering
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Proceedings of the National Academy of Sciences of the United States of America
Atom and Molecular Physics and Optics

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