QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online October 19, 2007
Journal of Experimental Biology 210, 3821-3829 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.007161

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kawano-Yamashita, E. Articles by Tamotsu, S. Search for Related Content PubMed PubMed Citation Articles by Kawano-Yamashita, E. Articles by Tamotsu, S.

Immunohistochemical characterization of a parapinopsin-containing photoreceptor cell involved in the ultraviolet/green discrimination in the pineal organ of the river lamprey Lethenteron japonicum

Emi Kawano-Yamashita^1,2, Akihisa Terakita^2,3,*, Mitsumasa Koyanagi², Yoshinori Shichida^3,4, Tadashi Oishi⁵ and Satoshi Tamotsu^1,*

¹ Graduate School of Humanities and Sciences, Nara Women's University, Nara 630-8506, Japan
² Department of Biology and Geosciences, Graduate School of Science, Osaka City University, Osaka 558-8585, Japan
³ Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Corporation, Kyoto 606-8502, Japan
⁴ Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
⁵ Nara Saho College, Nara 630-8566, Japan

^* Authors for correspondence (e-mails: terakita{at}sci.osaka-cu.ac.jp; tamotsu{at}cc.nara-wu.ac.jp)

Accepted 16 August 2007

In the pineal organ, two types of ganglion cell exhibit antagonistic chromatic responses to UV and green light, and achromatic responses to visible light. In this study, we histologically characterized UV-sensitive photoreceptor cells that contain a unique non-visual UV pigment, lamprey parapinopsin, in order to elucidate the neural network that is associated with antagonistic chromatic responses. These characteristics were compared with those of lamprey rhodopsin-containing cells, most of which are involved in achromatic responses. RT-PCR analysis revealed that lamprey parapinopsin was expressed in the pineal organ but not in the retina, unlike lamprey rhodopsin, which was expressed in both. Lamprey parapinopsin and lamprey rhodopsin were immunohistochemically localized in the dorsal and ventral regions of the pineal organ, respectively. The two pigments were localized in distinct photoreceptor cells throughout the pineal organ, namely the dorsal and ventral regions as well as the peripheral region, which corresponds to the dorso-ventral border region. The ratio of the number of lamprey parapinopsin-containing cells to lamprey rhodopsin-containing cells around the peripheral region was higher than in the central region. Electron-microscopic analysis revealed that lamprey parapinopsin-containing dorsal cells have outer segments and synaptic ribbons similar to those of ventral photoreceptor cells. However, unlike lamprey rhodopsin-containing cells, lamprey parapinopsin-containing cells connected with each other in a wide area of dorsal and peripheral portions and made direct contact with ganglion cells, mainly in the peripheral portion. These results suggest that UV light information captured by lamprey parapinopsin-containing photoreceptor cells is converged and directly transmitted to chromatic-type ganglion cells in the peripheral region to generate antagonistic chromatic responses.

Key words: pineal organ, parapinopsin, rhodopsin, ganglion cell, antagonistic chromatic response