Monday, 27 May 2013

Giardia is a cute flagellate with two nuclei, eight flowing flagella and an impressive sucker plate that makes it look rather like a catfish. Their elegant swimming patterns are reminiscent of one as well. Giardia also lacks canonical mitochondria, instead harbouring highly reduced derivatives called mitosomes. Thus, it's not particularly fond of oxygen -- recall that mitochondria are involved in oxygen-based respiration. As far as lifestyles go, that usually means one of two things: either they love rotting black goo purged of much of the oxygen by the decay activity; or they inhabit some other critter. Thus, many anaerobes are symbionts: mutualists or parasites (or commensals). Note that by far, not all parasites and mutualists are anaerobes.Oh, I should probably mention a minor detail: Giardia is notorious for giardiasis -- also known as beaver fever -- a nasty disease obtained from drinking outdoor -- and otherwise contaminated -- water, especially from slow-moving streams and water downstream of dead animals, faeces, etc. To normal, well-balanced people, this means Giardia is to be avoided at all costs, and that research must be done to either get rid of it or make the sickness marginally more bearable. To a protist nut, the clinical importance means we can have a better understanding of a phylogenetically unique and fascinating model organism. Excavates , the group containing Giardia , are diverse but not particularly well-understood. Naegleria and trypanosomes are fellow opportunists and parasites, respectively, who bring ire upon humans and attract scientific funding. Giardia is on the other branch of the most basic divide between groups of Excavates, however -- closer to the enigmatic parabasalids and oxymonads of the termite gut. Oh, and they're also literally double cells -- two nuclei, and two sets of four flagella, in a mirrored arrangement. What more can a cell biologist want? [More]


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