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Owls lack UV-sensitive cone opsin and red oil droplets, but see UV light at night : Retinal transcriptomes and ocular media transmittance

Höglund, Julia; Mitkus, Mindaugas LU ; Olsson, Peter LU ; Lind, Olle LU ; Drews, Anna LU ; Bloch, Natasha I.; Kelber, Almut LU and Strandh, Maria LU (2019) In Vision Research 158. p.109-119
Abstract

Most diurnal birds have cone-dominated retinae and tetrachromatic colour vision based on ultra-violet/violet-sensitive UV/V cones expressing short wavelength-sensitive opsin 1 (SWS1), S cones expressing short wavelength-sensitive opsin 2 (SWS2), M cones expressing medium wavelength-sensitive opsin (RH2) and L cones expressing long wavelength-sensitive opsin (LWS). Double cones (D) express LWS but do not contribute to colour vision. Each cone is equipped with an oil droplet, transparent in UV/V cones, but pigmented by carotenoids: galloxanthin in S, zeaxanthin in M, astaxanthin in L and a mixture in D cones. Owls (Strigiformes) are crepuscular or nocturnal birds with rod-dominated retinae and optical adaptations for high sensitivity. For... (More)

Most diurnal birds have cone-dominated retinae and tetrachromatic colour vision based on ultra-violet/violet-sensitive UV/V cones expressing short wavelength-sensitive opsin 1 (SWS1), S cones expressing short wavelength-sensitive opsin 2 (SWS2), M cones expressing medium wavelength-sensitive opsin (RH2) and L cones expressing long wavelength-sensitive opsin (LWS). Double cones (D) express LWS but do not contribute to colour vision. Each cone is equipped with an oil droplet, transparent in UV/V cones, but pigmented by carotenoids: galloxanthin in S, zeaxanthin in M, astaxanthin in L and a mixture in D cones. Owls (Strigiformes) are crepuscular or nocturnal birds with rod-dominated retinae and optical adaptations for high sensitivity. For eight species, the absence of functional SWS1 opsin has recently been documented, functional RH2 opsin was absent in three of these. Here we confirm the absence of SWS1 transcripts for the Long-eared owl (Asio otus) and demonstrate its absence for the Short-eared owl (Asio flammeus), Tawny owl (Strix aluco) and Boreal owl (Aegolius funereus). All four species had transcripts of RH2, albeit with low expression. All four species express all enzymes needed to produce galloxanthin, but lack CYP2J19 expression required to produce astaxanthin from dietary precursors. We also present ocular media transmittance of the Eurasian eagle owl (Bubo bubo) and Short-eared owl and predict spectral sensitivities of all photoreceptors of the Tawny owl. We conclude that owls, despite lacking UV/V cones, can detect UV light. This increases the sensitivity of their rod vision allowing them, for instance, to see UV-reflecting feathers as brighter signals at night.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Gene expression, Night vision, Ocular media transmittance, Opsin, Owls, Retina transcriptome, Strigiformes, UV-sensitivity
in
Vision Research
volume
158
pages
11 pages
publisher
Elsevier
external identifiers
  • scopus:85062475875
ISSN
0042-6989
DOI
10.1016/j.visres.2019.02.005
language
English
LU publication?
yes
id
c3beaa92-7dda-4950-9003-37da1cc5da15
date added to LUP
2019-03-12 12:04:03
date last changed
2019-04-10 04:20:48
@article{c3beaa92-7dda-4950-9003-37da1cc5da15,
  abstract     = {<p>Most diurnal birds have cone-dominated retinae and tetrachromatic colour vision based on ultra-violet/violet-sensitive UV/V cones expressing short wavelength-sensitive opsin 1 (SWS1), S cones expressing short wavelength-sensitive opsin 2 (SWS2), M cones expressing medium wavelength-sensitive opsin (RH2) and L cones expressing long wavelength-sensitive opsin (LWS). Double cones (D) express LWS but do not contribute to colour vision. Each cone is equipped with an oil droplet, transparent in UV/V cones, but pigmented by carotenoids: galloxanthin in S, zeaxanthin in M, astaxanthin in L and a mixture in D cones. Owls (Strigiformes) are crepuscular or nocturnal birds with rod-dominated retinae and optical adaptations for high sensitivity. For eight species, the absence of functional SWS1 opsin has recently been documented, functional RH2 opsin was absent in three of these. Here we confirm the absence of SWS1 transcripts for the Long-eared owl (Asio otus) and demonstrate its absence for the Short-eared owl (Asio flammeus), Tawny owl (Strix aluco) and Boreal owl (Aegolius funereus). All four species had transcripts of RH2, albeit with low expression. All four species express all enzymes needed to produce galloxanthin, but lack CYP2J19 expression required to produce astaxanthin from dietary precursors. We also present ocular media transmittance of the Eurasian eagle owl (Bubo bubo) and Short-eared owl and predict spectral sensitivities of all photoreceptors of the Tawny owl. We conclude that owls, despite lacking UV/V cones, can detect UV light. This increases the sensitivity of their rod vision allowing them, for instance, to see UV-reflecting feathers as brighter signals at night.</p>},
  author       = {Höglund, Julia and Mitkus, Mindaugas and Olsson, Peter and Lind, Olle and Drews, Anna and Bloch, Natasha I. and Kelber, Almut and Strandh, Maria},
  issn         = {0042-6989},
  keyword      = {Gene expression,Night vision,Ocular media transmittance,Opsin,Owls,Retina transcriptome,Strigiformes,UV-sensitivity},
  language     = {eng},
  pages        = {109--119},
  publisher    = {Elsevier},
  series       = {Vision Research},
  title        = {Owls lack UV-sensitive cone opsin and red oil droplets, but see UV light at night : Retinal transcriptomes and ocular media transmittance},
  url          = {http://dx.doi.org/10.1016/j.visres.2019.02.005},
  volume       = {158},
  year         = {2019},
}