Cone photoreceptor oil droplet pigmentation is affected by ambient light intensity

Hart, Nathan S, Lisney, Thomas J. and Collin, Shaun P. (2006) Cone photoreceptor oil droplet pigmentation is affected by ambient light intensity. Journal of Experimental Biology, 209 23: 4776-4787. doi:10.1242/jeb.02568

Attached Files (Some files may be inaccessible until you login with your UQ eSpace credentials)
Name Description MIMEType Size Downloads
UQ81396_OA.pdf Full text (open access) application/pdf 323.10KB 0

Author Hart, Nathan S
Lisney, Thomas J.
Collin, Shaun P.
Title Cone photoreceptor oil droplet pigmentation is affected by ambient light intensity
Journal name Journal of Experimental Biology   Check publisher's open access policy
ISSN 0022-0949
Publication date 2006-12
Sub-type Article (original research)
DOI 10.1242/jeb.02568
Open Access Status File (Publisher version)
Volume 209
Issue 23
Start page 4776
End page 4787
Total pages 12
Editor H. Hoppeler
Place of publication Cambridge, United Kingdom
Publisher Company of Biologists
Collection year 2006
Language eng
Subject 270502 Neurobiology
780105 Biological sciences
060805 Animal Neurobiology
Abstract The cone photoreceptors of many vertebrates contain spherical organelles called oil droplets. In birds, turtles, lizards and some lungfish the oil droplets are heavily pigmented and function to filter the spectrum of light incident upon the visual pigment within the outer segment. Pigmented oil droplets are beneficial for colour discrimination in bright light, but at lower light levels the reduction in sensitivity caused by the pigmentation increasingly outweighs the benefits generated by spectral tuning. Consequently, it is expected that species with pigmented oil droplets should modulate the density of pigment in response to ambient light intensity and thereby regulate the amount of light transmitted to the outer segment. In this study, microspectrophotometry was used to measure the absorption spectra of cone oil droplets in chickens (Gallus gallus domesticus) reared under bright (unfiltered) or dim (filtered) sunlight. Oil droplet pigmentation was found to be dependent on the intensity of the ambient light and the duration of exposure to the different lighting treatments. In adult chickens reared in bright light, the oil droplets of all cone types (except the violet-sensitive single cones, whose oil droplet is always non-pigmented) were more densely pigmented than those in chickens reared in dim light. Calculations show that the reduced levels of oil droplet pigmentation in chickens reared in dim light would increase the sensitivity and spectral bandwidth of the outer segment significantly. The density of pigmentation in the oil droplets presumably represents a trade-off between the need for good colour discrimination and absolute sensitivity. This might also explain why nocturnal animals, or those that underwent a nocturnal phase during their evolution, have evolved oil droplets with low pigment densities or no pigmentation or have lost their oil droplets altogether.
Keyword Microspectrophotometry
Avian colour vision
Photon catch
Spectral tuning
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 37 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 39 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Wed, 15 Aug 2007, 09:43:31 EST