Science Serving Maryland's Coasts

Student Research Publications

Cryptophyte algae are robbed of their organelles by the marine ciliate Mesodinium rubrum




Gustafson, D. E., D. K. Stoecker, M. D. Johnson, W. F. Van Heukelem, and K. Sneider*


Nature 405:1049-1052


Mesodinium rubrum (Lohmann 1908) Jankowski 1976 (= Myrionecta rubra) is a common photosynthetic marine planktonic ciliate which can form coastal red-tides. It may represent a 'species complex'(4,5) and since Darwin's voyage on the Beagle, it has been of great cytological, physiological and evolutionary interest. It is considered to be functionally a phytoplankter because it was thought to have lost the capacity to feed and possesses a highly modified algal endosymbiont. Whether M. rubrum is the result of a permanent endosymbiosis or a transient association between a ciliate and an alga is controversial. We conducted 'feeding' experiments to determine how exposure to a cryptophyte alga affects M. rubrum. Here we show that although M. rubrum lacks a cytostome (oral cavity)(8), it ingests cryptophytes and steals their organelles, and may not maintain a permanent endosymbiont. M. rubrum does not fall into recognized cellular or functional categories, but may be a chimaera partially supported by organelle robbery.


Diane Stoecker, Ph.D.


Kerri Sneider, Southampton College

The REU students are indicated with an asterisk (*).