Abstract
Sacoglossan sea slugs are able to maintain functional chloroplasts inside their own cells, and mechanisms that allow preservation of the chloroplasts are unknown. We found that the slug Elysia timida induces changes to the photosynthetic light reactions of the chloroplasts it steals from the alga Acetabularia acetabulum. Working with a large continuous laboratory culture of both the slugs (>500 individuals) and their prey algae, we show that the plastoquinone pool of slug chloroplasts remains oxidized, which can suppress reactive oxygen species formation. Slug chloroplasts also rapidly build up a strong proton motive force upon a dark-to-light transition, which helps them to rapidly switch on photoprotective non-photochemical quenching of excitation energy. Finally, our results suggest that chloroplasts inside E. timida rely on oxygen-dependent electron sinks during rapid changes in light intensity. These photoprotective mechanisms are expected to contribute to the long-term functionality of the chloroplasts inside the slugs.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 2, 3, 4, Figure 4-figure supplement 1 and Figures 5, 6, 7B-E and 8.
Article and author information
Author details
Funding
Academy of Finland (307335)
- Esa Tyystjärvi
Suomen Kulttuurirahasto (Graduate student grant)
- Vesa Havurinne
Suomalainen Tiedeakatemia (Graduate student grant)
- Vesa Havurinne
University of Turku graduate school, DPMLS (Graduate student grant)
- Vesa Havurinne
Academy of Finland (333421)
- Esa Tyystjärvi
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: This study was performed in accordance with EU legislation and directives concerning scientific research on non-cephalopod invertebrates.
Reviewing Editor
- Christian S Hardtke, University of Lausanne, Switzerland
Publication history
- Received: March 30, 2020
- Accepted: October 7, 2020
- Accepted Manuscript published: October 20, 2020 (version 1)
- Version of Record published: November 20, 2020 (version 2)
Copyright
© 2020, Havurinne & Tyystjärvi
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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