The visual pigment xenopsin is widespread in protostome eyes and impacts the view on eye evolution

Abstract
Data availability
Article and author information
Metrics

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.

Data availability

Sequencing data have been deposited in Genbank under accession codes MT901639, MT901640, and MT901641. Source data files have been provided for Figures 2 and 5.

The following data sets were generated

1. Doering CC
2. Kumar S
3. Tumu S
4. Kourtesis I
5. Hausen H
(2020) Malacoceros fuliginosus xenopsin gene, partial cds
Genbank, MT901639.

https://www.ncbi.nlm.nih.gov/nuccore/MT901639
1. Doering CC
2. Kumar S
3. Tumu S
4. Kourtesis I
5. Hausen H
(2020) Malacoceros fuliginosus ciliary opsin gene, complete cds
Genbank, MT901640.

https://www.ncbi.nlm.nih.gov/nuccore/MT901640
1. Doering CC
2. Kumar S
3. Tumu S
4. Kourtesis I
5. Hausen H
(2020) Tricellaria inopinata xenopsin gene, partial cds
Genbank, MT901641.

https://www.ncbi.nlm.nih.gov/nuccore/MT901641

Article and author information

Author details

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.
Suman Kumar

Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway

Competing interests
The authors declare that no competing interests exist.
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.
Ioannis Kourtesis

Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway

Competing interests
The authors declare that no competing interests exist.
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.

"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.

Copyright

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.