iBet uBet web content aggregator. Adding the entire web to your favor.
iBet uBet web content aggregator. Adding the entire web to your favor.



Link to original content: https://www.ncbi.nlm.nih.gov/pubmed/15888411
Cone topography and spectral sensitivity in two potentially trichromatic marsupials, the quokka (Setonix brachyurus) and quenda (Isoodon obesulus) - PubMed Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Comparative Study
. 2005 Apr 22;272(1565):791-6.
doi: 10.1098/rspb.2004.3009.

Cone topography and spectral sensitivity in two potentially trichromatic marsupials, the quokka (Setonix brachyurus) and quenda (Isoodon obesulus)

Catherine A Arrese  1 , Alison Y Oddy, Philip B Runham, Nathan S Hart, Julia Shand, David M Hunt, Lyn D Beazley
Affiliations
Comparative Study

Cone topography and spectral sensitivity in two potentially trichromatic marsupials, the quokka (Setonix brachyurus) and quenda (Isoodon obesulus)

Catherine A Arrese et al. Proc Biol Sci. .

Abstract

The potential for trichromacy in mammals, thought to be unique to primates, was recently discovered in two Australian marsupials. Whether the presence of three cone types, sensitive to short- (SWS), medium- (MWS) and long- (LWS) wavelengths, occurs across all marsupials remains unknown. Here, we have investigated the presence, distribution and spectral sensitivity of cone types in two further species, the quokka (Setonix brachyurus) and quenda (Isoodon obesulus). Immunohistochemistry revealed that SWS cones in the quokka are concentrated in dorso-temporal retina, while in the quenda, two peaks were identified in naso-ventral and dorso-temporal retina. In both species, MWS/LWS cone spatial distributions matched those of retinal ganglion cells. Microspectrophotometry (MSP) confirmed that MWS and LWS cones are spectrally distinct, with mean wavelengths of maximum absorbance at 502 and 538 nm in the quokka, and at 509 and 551 nm, in the quenda. Although small SWS cone outer segments precluded MSP measurements, molecular analysis identified substitutions at key sites, accounting for a spectral shift from ultraviolet in the quenda to violet in the quokka. The presence of three cone types, along with previous findings in the fat-tailed dunnart and honey possum, suggests that three spectrally distinct cone types are a feature spanning the marsupials.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Immunolabelling of quokka (a,c) and quenda (f,h) retinae. Photomicrographs of wholemounts treated with JH455 (a,f) and JH492 (c,h). Scale bar, 8 μm. Contour maps for each cone type in quokka (b,d) and quenda (g,i): darker shades indicate highest densities, lighter shades, lowest densities. Retinal ganglion cell topographies in quokka (e; modified from Beazley & Dunlop 1983) and quenda (j; modified from Tancred 1981), showing distributions similar to M/LWS cones.
Figure 2
Figure 2
Wholemounted retina of quenda incubated with JH455 and JH492 revealing the presence of unlabelled outer segments (arrow head). Scale bar, 10 μm.
Figure 3
Figure 3
The diprotodont quokka (a) and polyprotodont quenda (a′). Normalized mean averaged absorbance spectra of visual pigments in the quokka (b–d) and quenda (b′–d′), showing pre-bleach spectra (upper traces) with best-fitted visual pigment templates (solid lines) and post-bleach spectra (lower traces) with running averages (solid lines). Scale bar, 10 cm.
Figure 4
Figure 4
Phylogenetic tree of marsupial SWS1 and other opsins generated by the neighbour-joining method (Saitou & Nei 1987) with 1000 bootstrap replications. The calibration bar shows substitutions per site. Amino acid sequences were aligned by Clustal X (Higgins et al. 1996).
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Ahnelt K.P, Kolb H. The mammalian photoreceptor mosaic-adaptive design. Prog. Retin. Eye Res. 2000;19:711–777. - PubMed
    1. Arrese C.A, Hart N.S, Thomas N, Beazley L.D, Shand J. Trichromacy in Australian marsupials. Curr. Biol. 2002;12:657–660. - PubMed
    1. Arrese C.A, Rodger J, Beazley L.D, Shand J. Topographies of retinal cone photoreceptors in two Australian marsupials. Vis. Neurosci. 2003;20:303–311. - PubMed
    1. Beazley L.D, Dunlop S.A. The evolution of the area centralis and visual streak in the marsupial Setonix brachyurus. J. Comp. Neurol. 1983;216:211–231. - PubMed
    1. Bowmaker J.K. Evolution of photoreceptors and visual pigments. In: Cronly-Dillon J.R, Gregory R.L, editors. In Evolution of the eye and visual pigments. CRC Press; Boca Raton, FL: 1991. pp. 63–81.

Publication types