Kerri Sneider, Southampton College

Class Year:



Diane Stoecker Ph.D.

Project Title:

Tracing the Uptake and Retention of Fluorescently Labeled Cryptophyte Algae by the Photosynthetic Ciliate, Mesodinium rubrum


 A protocol for the live-staining of cryptophyte algae was developed to trace the uptake and retention of cryptophyte nuclei and plastids by Mesodinium rubrum, a photosynthetic species. The algae were able to be stained with SytoTM under certain conditions, however, prolonged exposure to the stain caused cells to die and lyse. Occasional unexplained loss of staining was seen on some slides prepared. The cryptophytes were not able to survive the washing procedure necessary for experimentation. Experiments performed under these conditions showed a direct effect of motility and perhaps viability on feeding of Mesodinium rubrum. Live cryptophytes were fed to Mesodinium, fixed and stained with DAPI and observed. This method was successful in showing the uptake of nuclei at different time increments. Uptake was seen within minutes and retention appeared to last for up to 72 hours after introduction of prey. Mesodinium is able to take in and retain more than seven cryptophyte nuclei at once. Nuclear staining is useful in feeding experiments to quantify the uptake of cryptophyte organelles by Mesodinium rubrum.


Gustafson, D. E., D. K. Stoecker, M. D. Johnson, W. F. Van Heukelem, and K. Sneider*. 2000. Cryptophyte algae are robbed of their organelles by the marine ciliate Mesodinium rubrum. Nature 405:1049-1052.

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

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