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Published on: August 19, 2014
Emergent metabolic parasitism driven by organelle sequestration
Holly V Moeller1, Erica Lasek-Nesselquist2,3, Zachary L Reitz1
1Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA, USA.
Science Advances
|August 7, 2026
Summary
Marine ciliates that steal chloroplasts for photosynthesis lose metabolic abilities. This study reveals that increased reliance on acquired photosynthesis leads to a loss of essential metabolic functions, challenging traditional views of endosymbiosis.
Area of Science:
- Marine biology
- Evolutionary biology
- Cell biology
Background:
- Stable metabolic acquisitions, like endosymbiosis, typically increase host genetic repertoire and integrate new metabolism.
- The marine ciliate genus *Mesodinium* provides a model for studying transitions from heterotrophy to phototrophy via chloroplast theft.
Purpose of the Study:
- To test predictions of metabolic acquisition during endosymbiosis using *Mesodinium* species.
- To investigate the relationship between reliance on acquired photosynthesis and metabolic autonomy.
Main Methods:
- Comparative transcriptome analysis of *Mesodinium* species across a phototrophy spectrum.
- Assessment of metabolic gene repertoire and functional capacities.
Main Results:
- Species with increased reliance on acquired photosynthesis showed significant metabolic divestment.
- *Mesodinium rubrum*, a highly photosynthetic species, lost the capacity for amino acid synthesis, fatty acid metabolism, and peroxisome production.
- Acquired photosynthesis in *Mesodinium* leads to a loss of metabolic autonomy.
Conclusions:
- The *Mesodinium* model challenges the paradigm that endosymbiosis always enhances host metabolic capabilities.
- Highly photosynthetic ciliates can become metabolic parasites, dependent on acquired organelles for survival.
- This study offers an alternative model for understanding the evolution of phototrophy from heterotrophy.
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