This is the first evidence that organisms with stolen chloroplasts (kleptochloroplasts) can have significant control over the physiological state and ‘health’ of their stolen chloroplasts. It was published yesterday in Frontiers in Microbiology.
Kleptochloroplasts, or stolen chloroplasts, are found in various aquatic organisms, most commonly in unicellular dinoflagellates and ciliates. The phenomenon arises when heterotrophic organisms catch phototrophic prey, but instead of degrading the entire prey cell, the heterotrophic predator degrades only parts of the prey and keeps the chloroplasts (and in some cases a few other cell components) for use in photosynthesis. In some cases the chloroplasts are only photosynthetically active for a short period of time, whereas in Dinophysis species, the chloroplasts can be active for months. Until now, it was unknown what, if any, physiological control the predator has over these stolen chloroplasts.
We show that the kleptoplastidic dinoflagellate Dinophysis acuta has a large degree of control of its stolen chloroplasts. It can synthesize photosynthetic as well as photoprotective pigments under long-term starvation in the light. Variable chlorophyll fluorescence measurements showed that the kleptochloroplasts were fully functional during 1 month of prey starvation, while the chlorophyll a-specific inorganic carbon uptake decreased within days of prey starvation under an irradiance of 100 μmol photons m-2 s-1. While D. acuta cells can regulate their pigmentation and function of kleptochloroplasts they apparently lose the ability to maintain high inorganic carbon fixation rates.
Read the paper here