Title: A complex carotenoid palette tunes avian color vision.

Abstract

The brilliantly coloured cone oil droplets of the avian retina function as long-pass cut-off filters that tune the spectral sensitivity of the photoreceptors and are hypothesized to enhance colour discrimination and improve colour constancy. Although it has long been known that these droplets are pigmented with carotenoids, their precise composition has remained uncertain owing to the technical challenges of measuring these very small, dense and highly refractile optical organelles. In this study, we integrated results from high-performance liquid chromatography, hyperspectral microscopy and microspectrophotometry to obtain a comprehensive understanding of oil droplet carotenoid pigmentation in the chicken ( Gallus gallus). We find that each of the four carotenoid-containing droplet types consists of a complex mixture of carotenoids, with a single predominant carotenoid determining the wavelength of the spectral filtering cut-off. Consistent with previous reports, we find that the predominant carotenoid type in the oil droplets of long-wavelength-sensitive, medium-wavelength-sensitive and short-wavelength-sensitive type 2 cones are astaxanthin, zeaxanthin and galloxanthin, respectively. In addition, the oil droplet of the principal member of the double cone contains a mixture of galloxanthin and two hydroxycarotenoids (lutein and zeaxanthin). Short-wavelength-absorbing apocarotenoids are present in all of the droplet types, providing filtering of light in a region ofmore » the spectrum where filtering by hydroxy- and ketocarotenoids may be incomplete. Furthermore, birds rely on a complex palette of carotenoid pigments within their cone oil droplets to achieve finely tuned spectral filtering.« less

Authors:

Timlin, Jerilyn A. ^[1]; Toomey, Matthew B. ^[2]; Collins, Aaron M. ^[3]; Frederiksen, Rikard ^[4]; Cornwall, M. Carter ^[4]; Corbo, Joseph C. ^[2]

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+ Show Author Affiliations

1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2. Washington Univ. School of Medicine, St. Louis, MO (United States)
3. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
4. Boston Univ. School of Medicine, Boston, MA (United States)

Publication Date:

2015-10-07

Research Org.:

Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)

OSTI Identifier:

1236232

Report Number(s):

SAND-2015-4230J
Journal ID: ISSN 1742-5689; 590324

Grant/Contract Number:  

AC04-94AL85000

Resource Type:

Accepted Manuscript

Journal Name:

Journal of the Royal Society Interface

Additional Journal Information:

Journal Volume: 12; Journal Issue: 111; Journal ID: ISSN 1742-5689

Publisher:

The Royal Society

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES