By Hayley Dunning -
Choanoflagellates, single-celled flagellates, have been thought of as a model for multicellularity since the 1800s because they live either as individuals or in colonies shaped like rosettes. The way colonies form is also intriguing: when daughter cells are spawned, they stick around instead of breaking up, in what looks at first glance like the dividing cells of an embryo. Now, in a paper to be published in the first issue of the upcoming open-access journal eLife, a driving factor of rosette formation has been uncovered. A sulfonolipid, produced by a bacteria that choanoflagellates eat, induces colony development, raising the possibility that bacteria were involved in the evolution of multicellular life.
“The origin of eukaryotic cells occurred in a really dense mass of bacteria,” said zoologist Michael Hadfield at the University of Hawaii, who was not involved in the study. There’s “just no way” that those first organisms weren’t involved with bacteria in many ways beyond just feeding on them, he said. “What this new paper shows us is that there’s this really fundamental connection going on here between [bacteria] and things that operate as single cells ,then start operating as colonies.” Read More.