Abstract
The marine mixotrophic ciliate Mesodinium rubrum is known to acquire chloroplasts, mitochondria, nucleomorphs, and nucleus from its cryptophyte prey, particularly from species in the genera, Geminigera and Teleaulax. The sequestered prey nucleus and chloroplasts are considered to support photosynthesis of M. rubrum. In addition, recent studies have shown enlargement of the retained prey nucleus in starved M. rubrum and have inferred that enlargement results from the fusion of ingested prey nuclei. Thus far, however, little is known about the mechanism underlying the enlargement of the prey nucleus in M. rubrum. Here, we conducted starvation and refeeding studies to monitor the fate of prey nuclei acquired by M. rubrum when feeding on Teleaulax amphioxeia and to explore the influence of the retained prey nucleus on photosynthesis of M. rubrum. Results indicate that enlargement of the prey nucleus does not result from fusion of nuclei. Furthermore, the enlarged prey nucleus does not appear to divide during cell division of M. rubrum. The presence of a prey nucleus significantly affected photosynthetic performance of M. rubrum, while the number of retained chloroplasts had little influence on rate of carbon fixation. We interpret results within the context of a model that considers the dynamics of ingested prey nuclei during division of M. rubrum.
Highlights
Mesodinium rubrum (=Myrionecta rubra) is a common ciliate in coastal waters worldwide, where it sometimes causes red tides (Taylor et al, 1971; Lindholm, 1985)
Dynamics of Acquired Prey Nucleus in Mesodinium rubrum genetically similar to the prey on which M. rubrum is fed, indicating that chloroplasts are sequestered from the prey (Johnson et al, 2006, 2007; Hansen et al, 2012; Myung et al, 2013)
Nuclei of Prey and Well-Fed Mesodinium rubrum Well-fed Mesodinium rubrum cells (Day 0 to Day 11) contain two ciliate macronuclei and one ciliate micronucleus, all of which were closely positioned at the center of the cell (Figure 2B)
Summary
Mesodinium rubrum (=Myrionecta rubra) is a common ciliate in coastal waters worldwide, where it sometimes causes red tides (Taylor et al, 1971; Lindholm, 1985). It is an obligate mixotroph, requiring both light and prey uptake for sustained growth and survival (Gustafson et al, 2000; Yih et al, 2004; Johnson and Stoecker, 2005; Hansen and Fenchel, 2006). M. rubrum requires continuous acquisition of new chloroplasts and other cell organelles acquired through feeding for sustained growth
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
