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Phototransduction in Anuran Green Rods: Origins of Extra-Sensitivity

Green rods (GRs) represent a unique type of photoreceptor to be found in the retinas of anuran amphibians. These cells harbor a cone-specific blue-sensitive visual pigment but exhibit morphology of the outer segment typical for classic red rods (RRs), which makes them a perspective model object for...

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Autores principales: Astakhova, Luba A., Novoselov, Artem D., Ermolaeva, Maria E., Firsov, Michael L., Rotov, Alexander Yu.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8707487/
https://www.ncbi.nlm.nih.gov/pubmed/34948198
http://dx.doi.org/10.3390/ijms222413400
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author Astakhova, Luba A.
Novoselov, Artem D.
Ermolaeva, Maria E.
Firsov, Michael L.
Rotov, Alexander Yu.
author_facet Astakhova, Luba A.
Novoselov, Artem D.
Ermolaeva, Maria E.
Firsov, Michael L.
Rotov, Alexander Yu.
author_sort Astakhova, Luba A.
collection PubMed
description Green rods (GRs) represent a unique type of photoreceptor to be found in the retinas of anuran amphibians. These cells harbor a cone-specific blue-sensitive visual pigment but exhibit morphology of the outer segment typical for classic red rods (RRs), which makes them a perspective model object for studying cone–rod transmutation. In the present study, we performed detailed electrophysiological examination of the light sensitivity, response kinetics and parameters of discrete and continuous dark noise in GRs of the two anuran species: cane toad and marsh frog. Our results confirm that anuran GRs are highly specialized nocturnal vision receptors. Moreover, their rate of phototransduction quenching appeared to be about two-times slower than in RRs, which makes them even more efficient single photon detectors. The operating intensity ranges for two rod types widely overlap supposedly allowing amphibians to discriminate colors in the scotopic region. Unexpectedly for typical cone pigments but in line with some previous reports, the spontaneous isomerization rate of the GR visual pigment was found to be the same as for rhodopsin of RRs. Thus, our results expand the knowledge on anuran GRs and show that these are even more specialized single photon catchers than RRs, which allows us to assign them a status of “super-rods”.
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spelling pubmed-87074872021-12-25 Phototransduction in Anuran Green Rods: Origins of Extra-Sensitivity Astakhova, Luba A. Novoselov, Artem D. Ermolaeva, Maria E. Firsov, Michael L. Rotov, Alexander Yu. Int J Mol Sci Article Green rods (GRs) represent a unique type of photoreceptor to be found in the retinas of anuran amphibians. These cells harbor a cone-specific blue-sensitive visual pigment but exhibit morphology of the outer segment typical for classic red rods (RRs), which makes them a perspective model object for studying cone–rod transmutation. In the present study, we performed detailed electrophysiological examination of the light sensitivity, response kinetics and parameters of discrete and continuous dark noise in GRs of the two anuran species: cane toad and marsh frog. Our results confirm that anuran GRs are highly specialized nocturnal vision receptors. Moreover, their rate of phototransduction quenching appeared to be about two-times slower than in RRs, which makes them even more efficient single photon detectors. The operating intensity ranges for two rod types widely overlap supposedly allowing amphibians to discriminate colors in the scotopic region. Unexpectedly for typical cone pigments but in line with some previous reports, the spontaneous isomerization rate of the GR visual pigment was found to be the same as for rhodopsin of RRs. Thus, our results expand the knowledge on anuran GRs and show that these are even more specialized single photon catchers than RRs, which allows us to assign them a status of “super-rods”. MDPI 2021-12-13 /pmc/articles/PMC8707487/ /pubmed/34948198 http://dx.doi.org/10.3390/ijms222413400 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Astakhova, Luba A.
Novoselov, Artem D.
Ermolaeva, Maria E.
Firsov, Michael L.
Rotov, Alexander Yu.
Phototransduction in Anuran Green Rods: Origins of Extra-Sensitivity
title Phototransduction in Anuran Green Rods: Origins of Extra-Sensitivity
title_full Phototransduction in Anuran Green Rods: Origins of Extra-Sensitivity
title_fullStr Phototransduction in Anuran Green Rods: Origins of Extra-Sensitivity
title_full_unstemmed Phototransduction in Anuran Green Rods: Origins of Extra-Sensitivity
title_short Phototransduction in Anuran Green Rods: Origins of Extra-Sensitivity
title_sort phototransduction in anuran green rods: origins of extra-sensitivity
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8707487/
https://www.ncbi.nlm.nih.gov/pubmed/34948198
http://dx.doi.org/10.3390/ijms222413400
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