Paulus Saari, Andrew S. French, Päivi H. Torkkeli, Hongxia Liu, Esa-Ville Immonen, Roman V. Frolov. Distinct roles of light-activated channels TRP and TRPL in photoreceptors of Periplaneta americana. The Journal of General Physiology Apr 2017, 149 (4) 455-464; DOI: 10.1085/jgp.201611737.
Distinct roles of light-activated channels TRP and TRPL in photoreceptors of Periplaneta americana
|Author:||Saari, Paulus1; French, Andrew S.2; Torkkeli, Päivi H.2;|
1Biophysics Group, Nano and Molecular Systems Research Unit, University of Oulu, Oulu FI ‑ 90014, Finland
2Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
3Lund Vision Group, Department of Biology, Lund University, 223 62 Lund, Sweden
|Online Access:||PDF Full Text (PDF, 1.3 MB)|
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe201804046332
Rockefeller University Press,
|Publish Date:|| 2018-04-04
Electrophysiological studies in Drosophila melanogaster and Periplaneta americana have found that the receptor current in their microvillar photoreceptors is generated by two light-activated cationic channels, TRP (transient receptor potential) and TRPL (TRP-like), each having distinct properties. However, the relative contribution of the two channel types to sensory information coding by photoreceptors remains unclear. We recently showed that, in contrast to the diurnal Drosophila in which TRP is the principal phototransduction channel, photoreceptors of the nocturnal P. americana strongly depend on TRPL. Here, we perform a functional analysis, using patch-clamp and intracellular recordings, of P. americana photoreceptors after RNA interference to knock down TRP (TRPkd) and TRPL (TRPLkd). Several functional properties were changed in both knockdown phenotypes: cell membrane capacitance was reduced 1.7-fold, light sensitivity was greatly reduced, and amplitudes of sustained light-induced currents and voltage responses decreased more than twofold over the entire range of light intensities. The information rate (IR) was tested using a Gaussian white-noise modulated light stimulus and was lower in TRPkd photoreceptors (28 ± 21 bits/s) than in controls (52 ± 13 bits/s) because of high levels of bump noise. In contrast, although signal amplitudes were smaller than in controls, the mean IR of TRPLkd photoreceptors was unchanged at 54 ± 29 bits/s¹ because of proportionally lower noise. We conclude that TRPL channels provide high-gain/high-noise transduction, suitable for vision in dim light, whereas transduction by TRP channels is relatively low-gain/low-noise and allows better information transfer in bright light.
The journal of general physiology
|Pages:||455 - 464|
|Type of Publication:||
A1 Journal article – refereed
|Field of Science:||
1184 Genetics, developmental biology, physiology
This research was supported by Natural Sciences and Engineering Research Council of Canada (NSERC) grants RGPIN/5565 (to P.H. Torkkeli) and RGPIN/03712 (to A.S. French).
© 2017 Saari et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms/). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 International license, as described at https