Volume 8, Number 4, Article 23, Pages 1-12 doi:10.1167/8.4.23 http://journalofvision.org/8/4/23/ ISSN 1534-7362
Cone photoreceptors and potential UV vision in a subterranean insectivore, the European mole
Martin Glösmann
Max Planck Institute for Brain Research, Frankfurt am Main, Germany, & Institute of Physiology, Medical University of Vienna, Vienna, Austria
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Marianne Steiner
Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
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Leo Peichl
Max Planck Institute for Brain Research, Frankfurt am Main, Germany
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Peter K. Ahnelt
Institute of Physiology, Medical University of Vienna, Vienna, Austria
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Abstract

We have examined the presence, the distribution, and the opsin identity of photoreceptor types in the retina of the European mole, Talpa europaea, a subterranean insectivore with regressed morphology of the visual system. Cones and rods were identified using opsin antisera, and their topographies determined from flat-mounted retinas. The retina (total area 0.75 mm2) contains about 100,000 photoreceptors, 10–12% of which are cones. Rod density is low (theoretical maximum 127,000 mm−2). Cone density peaks in central retina (17,750 mm−2). Similar to most mammals, two cone opsins, shortwave-sensitive (S) and middle-to-long-wave-sensitive (M), are present. Cone distribution shows a dorsoventral gradient with higher S cone numbers in ventral retina. Coexpression of S and M opsin occurs in more than 30% of the cones. Partial sequencing of the S opsin gene strongly supports UV sensitivity of the mole S cone photopigment. Amino acids that spectrally tune the S opsin are identical in T. europaea and in mammals with known UV cone photosensitivity. The lens transmits light down to 300 nm. Together, our data suggest that photopic vision and UV sensitivity of a cone pigment play a functional role in the European mole.

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History
Received November 7, 2007; published April 23, 2008
Citation
Glösmann, M., Steiner, M., Peichl, L., & Ahnelt, P. K. (2008). Cone photoreceptors and potential UV vision in a subterranean insectivore, the European mole. Journal of Vision, 8(4):23, 1-12, http://journalofvision.org/8/4/23/, doi:10.1167/8.4.23.
Keywords
mammalian retina, visual pigments, opsin coexpression, subterranean mammals
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