Thursday, October 18, 2007

Chlamydomonas swims across the line

Last week's Science contained the publication of the Chlamydomonas reinhardtii genome, an old friend of mine from my undergraduate days. One thing I find particularly illuminating is how the focus of Chlamydomonas research has shifted.

Chlamydomonas has been studied for a long time, and was the system where the uniparental genetics of organelles was discovered. Chlamy has two flagella, and a lot of genetics on flagellar function had been performed in the system. But, in general it was viewed as a convenient model system for studying photosynthesis and nutrient uptake. If I remember reasonably well, in the late '80s it was probably 75:25 plant physiology:flagellar function in the literature, and the flagellar work was viewed as basic cell biology. Most publications were either in basic cell biology journals or plant journals, with the most notable paper in a flashy journal being the report of a separate basal body genome -- a finding which has not withstood the test of time.

Around the time I was graduating, it looked like interest in Chlamy might fade. Genetic transformation had finally been developed, but a new model plant had shown up: Arabidopsis. It had many of the desirable characteristics of Chlamy (such as packing a lot into a small space), but the molecular genetic tools were being developed amazingly rapidly & as a land plant (and relative to some of kids' least favorite vegetables) appeared more desirable.

Chlamy's two flagella make it unusual, as land plants and fungi lack flagella. So the genome paper, and some earlier papers, really pounces on this. Flagella have gone from just being interesting cellular structures to interesting cellular structures with a lot of human disease interest. By performing various taxonomic comparisons, genes can be identified as present in all flagellum-bearing species but no non-flagellated ones, being conserved in photosynthetic eukaryotes but universally absent from non-photosynthetic ones. Lots of good stuff there.

What next for the plant that swims? Googling & PubMed reveal interest in biofuels & bioremediation. Chlamydomonas is hot -- and going to stay that way.

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