1. Evolutionary Biology
  2. Neuroscience
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The visual pigment xenopsin is widespread in protostome eyes and impacts the view on eye evolution

Research Article
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Cite this article as: eLife 2020;9:e55193 doi: 10.7554/eLife.55193

Abstract

Photoreceptor cells in the eyes of Bilateria are often classified into microvillar cells with rhabdomeric opsin and ciliary cells with ciliary opsin, each type having specialized molecular components and physiology. First data on the recently discovered xenopsin point towards a more complex situation in protostomes. In this study, we provide clear evidence that xenopsin enters cilia in the eye of the larval bryozoan Tricellaria inopinata and triggers phototaxis. As reported from a mollusc, we find xenopsin coexpressed with rhabdomeric-opsin in eye photoreceptor cells bearing both microvilli and cilia in larva of the annelid Malacoceros fuliginosus. This is the first organism known to have both xenopsin and ciliary opsin, showing that these opsins are not necessarily mutually exclusive. Compiling existing data, we propose that xenopsin may play an important role in many protostome eyes and provides new insights into the function, evolution, and possible plasticity of animal eye photoreceptor cells.

Article and author information

Author details

  1. Clemens Christoph Döring

    Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway
    Competing interests
    The authors declare that no competing interests exist.
  2. Suman Kumar

    Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway
    Competing interests
    The authors declare that no competing interests exist.
  3. Sharat Chandra Tumu

    Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway
    Competing interests
    The authors declare that no competing interests exist.
  4. Ioannis Kourtesis

    Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway
    Competing interests
    The authors declare that no competing interests exist.
  5. Harald Hausen

    Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway
    For correspondence
    harald.hausen@uib.no
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-2788-2835

Funding

European Commission (FP7-PEOPLE-2012-ITN 317172 (NEPTUNE))

  • Harald Hausen

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Dan Larhammar, Uppsala University, Sweden

Publication history

  1. Received: January 15, 2020
  2. Accepted: September 1, 2020
  3. Accepted Manuscript published: September 3, 2020 (version 1)

Copyright

© 2020, Döring et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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