In a new study published in the journal eLife, Nicole King and her team at the University of California, Berkeley, are recapitulating the move from unicellular life to multicellular life using choanoflagellates and bacteria, says Not Exactly Rocket Science's Ed Yong. In working with the choanoflagellates — which normally live as single cells — King and her team found that the cells tend to form colonies when exposed to a molecule called RIF-1, which is produced by some bacteria eaten by choanoflagellates. This, Yong says, leads the researchers to believe that evolution was aided by the bacteria early organisms were exposed to.
King's team worked for years to determine how and why choanoflagellates form colonies — something that had been observed, but never explained. So they decided to sequence the genome of the choanoflagellate Salpingoeca rosetta, and found that the bacteria the cells had been fed with had inserted some of their own genes into the cells, Yong says. Now, he adds, the researchers believe that molecules like RIF-1 may have influenced evolutionary biology.