LA JOLLA, CA-One of the most pivotal steps in evolution-the transition from unicellular to multicellular organisms-may not have required as much retooling as commonly believed, found a globe-spanning collaboration of scientists led by researchers at the Salk Institute for Biological Studies and the US Department of Energy's Joint Genome Institute.
A comparison of the genomes of the multicellular algae Volvox carteri and its closest unicellular relative Chlamydomonas reinhardtii revealed that multicellular organisms may have been able to build their more complex molecular machinery largely from the same list of parts that was already available to their unicellular ancestors.
"If you think of proteins in terms of lego bricks Chlamydomonas already had a great lego set," says James Umen, Ph.D., assistant professor in the Plant Molecular and Cellular Biology Laboratory at the Salk Institute. "Volvox didn't have to buy a new one, and instead could experiment with what it had inherited from its ancestor."
Altogether the findings, published in this week's edition of the journal Science, suggest that very limited protein-coding innovation occurred in the Volvox lineage. "We expected that there would be some major differences in genome size, number of genes, or gene families sizes between Volvox and Chlamydomonas," says Umen. "Mostly that turned out not to be the case."
The evolution of multicellularity occurred repeatedly and independently in diverse lineages including animals, plants, fungi, as well as green and red algae. "This transition is one of the great evolutionary events that shaped life on earth," says co-first author Simon E. Prochnik, Ph.D., a Computationial Scientist at the DOE Joint Genome Institute. "It has generated much thought and speculation about what makes multicellular organisms different or more complex than their unicellular ancestors."
|Contact: Susan Trebach|