Publication Date:
2022-05-26
Description:
© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Rawlinson, K. A., Lapraz, F., Ballister, E. R., Terasaki, M., Rodgers, J., McDowell, R. J., Girstmair, J., Criswell, K. E., Boldogkoi, M., Simpson, F., Goulding, D., Cormie, C., Hall, B., Lucas, R. J., & Telford, M. J. Extraocular, rod-like photoreceptors in a flatworm express xenopsin photopigment. Elife, 8, (2019): e45465, doi: 10.7554/eLife.45465.
Description:
Animals detect light using opsin photopigments. Xenopsin, a recently classified subtype of opsin, challenges our views on opsin and photoreceptor evolution. Originally thought to belong to the Gαi-coupled ciliary opsins, xenopsins are now understood to have diverged from ciliary opsins in pre-bilaterian times, but little is known about the cells that deploy these proteins, or if they form a photopigment and drive phototransduction. We characterized xenopsin in a flatworm, Maritigrella crozieri, and found it expressed in ciliary cells of eyes in the larva, and in extraocular cells around the brain in the adult. These extraocular cells house hundreds of cilia in an intra-cellular vacuole (phaosome). Functional assays in human cells show Maritigrella xenopsin drives phototransduction primarily by coupling to Gαi. These findings highlight similarities between xenopsin and c-opsin and reveal a novel type of opsin-expressing cell that, like jawed vertebrate rods, encloses the ciliary membrane within their own plasma membrane.
Description:
We thank Andrew Gillis and Ariane Dimitris for help in the field, Kasia Hammar, Paul Linser, Anne Zakrzewski and Sidney Tamm for support in electron microscopy fixation, analysis and interpretation, Elaine Seaver and Danielle de Jong for helping to establish an in situ hybridization protocol for the Maritigrella crozieri larval stage, and Matthew Berriman and Michael Akam (Isaac Newton Trust grant (15.4(n)) for support in securing funding to complete this work. We thank the two reviewers whose comments and suggestions helped improve and clarify this manuscript.
The research was supported by a a Wellcome Trust Janet Thornton Fellowship (WT206194) to KR, a research exchange award to KR through the EDEN NSF Network (National Foundation Grant Number IOS-0955517 to Cassandra G Extavour), a Natural Sciences and Engineering Research grant (A5056) to BKH and by a Biotechnology and Biological Sciences Research Council grant (BB/H006966/1) (FL) and a Leverhulme Trust grant (F/07 134/DA) to MT. MT is supported by European Research Council (ERC-2012-AdG 322790).
Repository Name:
Woods Hole Open Access Server
Type:
Article
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