Top left: Confocal microscope image of a Tetrahymena thermophila cell, courtesy of Jason Brown
and Jacek Gaertig, University of Georgia. The cilia are revealed by green immunofluorescence, using anti-tubulin
antibodies. The macronucleus shows blue fluorescence after DAPI staining. This image was featured in the cover
of Nature Biotechnology, vol. 17, issue #5, May 1999. It highlighted the article on pp. 462-5 entitled "Surface
display of a parasite antigen in the ciliate Tetrahymena thermophila", by Gaertig J; Gao Y; Tishgarten
T; Clark TG and Dickerson HW.
Bottom left: The two nuclear genomes of Tetrahymena thermophila.
The micronucleus (MIC) contains the germline genome, composed of five pairs of metacentric chromosomes; the dots represent centromeres. The MIC genome is not expressed.
The macronucleus (MAC) contains the expressed genome and detrmines the cell's phenotype. It consists of small acentromeric chromosomes, generated by site-specific fragmentation of the germline genome. The bulk of the MAC genome is ~45-ploid.
For more details, see the Introduction to Tetrahymena genetics.
This diagram was produced by Dorothy J. McLaren, Instructional Resources, UCSB.