Visual Neuroscience

Research Articles

Microspectrophotometric and immunocytochemical identification of ultraviolet photoreceptors in geckos

E. R. Loewa1, V. I. Govardovskiia2, P. Röhlicha3 and Á. Széla3

a1 Department and Section of Physiology, Cornell University, Ithaca

a2 Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia

a3 Laboratory I of Electron Microscopy and 2nd Department of Anatomy, Histology and Embryology, Semmelweis University of Medicine, Budapest, Hungary

Abstract

Retinas of the nocturnal geckos, Hemidactylus turcicus, Hemidactylus garnotii, and Teratoscincus scincus, were studied with microspectrophotometry and immunocytochemistry against various visual pigment epitopes to reveal UV-sensitive photoreceptors. From 6–20% of the thinner members of type C double photoreceptors, earlier believed to be blue-sensitive, were found to contain a UV-absorbing visual pigment with λmax at 363–366 nm. The pigment had bleaching and dichroic properties typical of other photoreceptor cell types of the retina. Presumptive UV-sensitive cells in retinal sections were “negatively” labeled as they did not react with either the cone-specific monoclonal antibody COS-1 or with the anti-rhodopsin polyclonal serum AO, which together labeled all of the remaining photoreceptor types (green-sensitive A singles, B doubles, and thicker members of C doubles, as well as the blue-sensitive majority of thinner members of C doubles). UV cells were moderately stained with the mAb K42–41 produced against the 5–6 loop of bovine rhodopsin, which also moderately labeled blue-sensitive cells. mAb OS-2 strongly stained all outer segments, including the UV-sensitive ones. Similarities between gecko UV visual pigments, and UV visual pigments of other vertebrates, as well as possible functional significance of these cells are discussed.

(Received February 06 1995)

(Accepted July 05 1995)

Footnotes

Reprint requests to: Ellis R. Loew, Department and Section of Physiology, Cornell University, Ithaca, NY 14853, USA.