CBS researchers sequence genome of alga that offers insights into many areas of investigation
Imagine a one-celled organism that behaves like an animal, but photosynthesizes like a plant. A treasure trove of evolutionary insight? A valuable tool for studying fundamental characteristics of multicellular plants and animals?
Yes, and yes. But no need to imagine. This amazing creature really exists—in the form of Chlamydomonas reinhardtii, a microscopic alga that informs research in everything from understanding kidney disease to reducing the threat of global warming.
“It’s like Al Capp’s Shmoo,” says Pete Lefebvre, professor of plant biology and an internationally renowned expert in Chlamydomonas genetics. “Its whole purpose was to be useful. A Shmoo could transform itself into anything its human wished for. Chlamydomonas has that kind of versatility for researchers.” [For those not familiar with L’il Abner, Al Capp’s Shmoo was a popular character during the 1950s in the long-running comic strip.]
Chlamydomonas’ value as a research subject took a giant leap forward last fall with the publication in the October 12 Science of the alga’s DNA sequence by an international team of researchers. Lefebvre and two other CBS faculty played key roles: Lefebvre isolated the DNA used for the sequencing effort. Anton Sanderfoot, assistant professor of plant biology, helped figure out the function of hundreds of the 15,256 genes identified through the effort. Carolyn Silflow, professor of plant biology, developed links between the Chlamydomonas genetic map and the genome sequence.
The genetic sequencing of the Chlamydomonas genome is particularly exciting because the alga is pertinent to so many areas of investigation. Chlamydomonas sits at the point in the evolutionary tree of life where green algae and land plants diverged, so the sequencing “provides a nice bridge between unicellular and multicellular plants, plus a connection to the rest of things that aren’t plants,” Sanderfoot says. Because it has a chloroplast, is single-celled, and is easy to grow and maintain, the alga is a superb subject for exploring plant biochemistry. The parts that propel it—a pair of flagella sprouting out its front end like little wiggly legs—are virtually identical to cilia that are movers and shakers in many mammalian organs, so it also makes a great model for studying various human diseases that arise from faulty functioning of such structures. In recent times, Chlamydomonas’ photosynthetic and hydrogen-producing capabilities have earned it a top spot in research aimed at producing renewable fuels and mitigating global warming as well.
Knowing the DNA sequence, Silflow says, makes it possible for researchers to adopt new and productive approaches to advancing these diverse lines of inquiry. “It allows us to interpret our research and plan our experiments in a much different way,” she says.
Lefebvre and other scientists around the world, for example, are delving into the DNA database using a computer tool called a BLAST search to look for genes found in both Chlamydomonas and other organisms. These genes can be studied to inform our understanding of—and potentially ability to repair or improve—the function they facilitate. “At the same time [the genome] is useful in and of itself,” Sanderfoot adds.
“It tells you a lot about how things came to be.” —Mary Hoff
