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Gewählte Publikation:

Publikationstyp: Zeitschriftenaufsatz
Dokumenttyp: Originalarbeit

Jahr: 2010

AutorInnen: Schleich, CE; Vielma, A; Glösmann, M; Palacios, AG; Peichl, L

Titel: Retinal photoreceptors of two subterranean tuco-tuco species (Rodentia, Ctenomys): morphology, topography, and spectral sensitivity.

Quelle: J Comp Neurol. 2010; 518(19):4001-4015



Autor/innen der Vetmeduni Vienna:

Glösmann Martin

Beteiligte Vetmed-Organisationseinheiten
Institut für Physiologie, Pathophysiologie und Biophysik, Abteilung für Physiologie, Pathophysiologie und experimentelle Endokrinologie


Abstract:
Traditionally, vision was thought to be useless for animals living in dark underground habitats, but recent studies in a range of subterranean rodent species have shown a large diversity of eye features, from small subcutaneous eyes to normal-sized functional eyes. We analyzed the retinal photoreceptors in the subterranean hystricomorph rodents Ctenomys talarum and Ctenomys magellanicus to elucidate whether adaptation was to their near-lightless burrows or rather to their occasional diurnal surface activity. Both species had normally developed eyes. Overall photoreceptor densities were comparatively low (95,000-150,000/mm(2) in C. magellanicus, 110,000-200,000/mm(2) in C. talarum), and cone proportions were rather high (10-31% and 14-31%, respectively). The majority of cones expressed the middle-to-longwave-sensitive (L) opsin, and a 6-16% minority expressed the shortwave-sensitive (S) opsin. In both species the densities of L and S cones were higher in ventral than in dorsal retina. In both species the tuning-relevant amino acids of the S opsin indicate sensitivity in the near UV rather than the blue/violet range. Photopic spectral electroretinograms were recorded. Unexpectedly, their sensitivity profiles were best fitted by the linear summation of three visual pigment templates with lambda(max) at 370 nm (S pigment, UV), at 510 nm (L pigment), and at 450 nm (an as-yet unexplained mechanism). Avoiding predators and selecting food during the brief aboveground excursions may have exerted pressure to retain robust cone-based vision in Ctenomys. UV tuning of the S cone pigment is shared with a number of other hystricomorphs.

Keywords Pubmed: Animals
Electroretinography
Eye/anatomy & histology
Eye/metabolism
Female
Humans
Light*
Male
Opsins/genetics
Opsins/metabolism
Photoreceptor Cells, Vertebrate/cytology*
Photoreceptor Cells, Vertebrate/metabolism*
Rodentia/anatomy & histology*
Sensory Thresholds*
Vision, Ocular/physiology*
Visual Fields


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