MY FAVORITE CELL - GIARDIA

The gut protozoan parasite, Giardia duodenalis, is the best characteri zed example of the most ancient eukaryotes, which are anaerobic and ap pear to be primitively amitochondrial. Apart from its obvious medical importance, Giardia is fascinating in its own right, Its prokaryotic-l ike anaerobic metabolism renders it selectively sensitive to some bact erial drugs, especially the nitroimidazoles, which are activated to fo rm toxic radicals, Other features, including an enzyme that reduces ox ygen directly to water, cysteine as the keeper of redox balance, a pla smid, and toxin-like genes are also distinctly prokaryotic-like. But, unlike prokaryotes, Giardia has a sophisticated, highly developed cyto skeleton, bounded nuclei, linear chromosomes capped with telomeric rep eats, and telomere positional regulation of gene expression. BioEssays 20: 256-263, 1998. (C) 1998 John Wiley & Sons, Inc.