Ciliary and rhabdomeric opsins are employed by cells differing fundamentally in structure and molecular physiology, such as ciliary vertebrate rods and cones and protostome microvillar eye photoreceptors. We report unprecedented cellular co-expression of rhabdomeric opsin and a visual pigment of the recently described xenopsins in larval eyes of a mollusk. The photoreceptors bear both microvilli and cilia and express orthologs to transporters for microvillar and ciliary opsin trafficking. Highly conserved but distinct gene structures suggest that xenopsins and ciliary opsins are of independent origin, irrespective of their mutually exclusive distribution in animals.Furthermore, we propose that frequent opsin gene loss had big influence on evolution, organization and function of brain and eye photoreceptor cells in bilaterian animals. Presence of xenopsin in eyes of even different design might be due to common origin and initial employment in a highly plastic photoreceptor cell type of mixed microvillar/ciliary organization.
- Harald Hausen
- Harald Hausen
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Russ Fernald, Reviewing Editor, Stanford University, United States
- Received: November 22, 2016
- Accepted: September 1, 2017
- Accepted Manuscript published: September 6, 2017 (version 1)
© 2017, Vöcking et al.
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