Photoacclimation and functional control of stolen organelles in Mesodinium rubrum by an enslaved nucleus

The enslavement of foreign organelles by protists for metabolic gain is a common phenomenon within aquatic ecosystems. Ciliates belonging to the Mesodinium rubrum species complex are unique in that they also steal a transcriptionally active prey nucleus, the kleptokaryon, from certain cryptophytes, enabling control and replication of stolen plastids and other organelles. Here we show that kleptokaryon-containing M. rubrum undergo the process of photoacclimation, changing pigment concentrations in response to light in a manner similar to their cryptophyte prey, Geminigera cryophila. The proteome and transcriptome of the G. cryophila nucleus were analyzed in M. rubrum (i.e. kleptokaryon) and in the free-living cryptophyte under changing light conditions.