Evolution and functional diversity of jellyfish opsins.
Cnidaria are the most basal animal phylum possessing complex eyes [1]. Their eyes predominantly use ciliary photoreceptor cells (c-PRCs) like vertebrates, whereas insect eyes use rhabdomeric photoreceptor cells (r-PRCs) [1-4]. These two cell types show not only different cytoarchitectures but distinct phototransduction cascades, which are triggered by the respective types of opsins (e.g., [5]), ciliary opsins (c-opsins) and rhabdomeric opsins (r-opsins) [6]. Recent reports suggested that the c- and r-PRCs and their respective opsins diverged at least before the deuterostome-protostome split [7-9]. To study the earlier evolution of animal PRCs and opsins, we investigated two hydrozoan jellyfishes. We report here the first-characterized cnidarian opsins. Molecular phylogeny revealed that the cloned 20 jellyfish opsins, together with all the opsins from a hydra and some from a sea anemone, are more closely related to the c-opsins than to any other major opsin subfamily, indicating that the divergence of c- and r-opsins antedates the Cnidaria-Bilateria split. Possible scenarios of animal PRC evolution are discussed. Furthermore, Cladonema opsins show several distinct tissue- and stage-specific expression patterns. The expression of specific opsins in the eyes suggests a role in vision, whereas that in the gonads suggests a role in light-controlled release of gametes.
Suga
Hiroshi
H
Department of Cell Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland.
Schmid
Volker
V
Gehring
Walter J
WJ
D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D019143:Evolution, Molecular; D005123:Eye / Q000378:metabolism; D006066:Gonads / Q000378:metabolism; D037402:Hydrozoa / Q000378:metabolism*; D008027:Light; D008969:Molecular Sequence Data; D010802:Phylogeny; D017299:Rod Opsins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D012726:Sexual Behavior, Animal / Q000528:radiation effects; D014785:Vision, Ocular
D018076:DNA, Complementary; D017299:Rod Opsins