October 27, 2016 at 02:28AM

Today I Learned: 1) ...a plausible reason a single-celled organism might evolve multicelluarlity. Yeast cells in the wild have an occasional mutation that prevents their cell walls from splitting apart when they divide. The result is that they form almost-clonal clumps. Lab yeast been selected to not clump, so they live almost entirely as separate cells. Question: under what circumstances might that clumping feature be selected for? Here's one. There are some nutrients that yeast can only absorb after they're digested outside the cell. For example, yeast can break down extracellular sucrose (which they cannot process directly) into glucose and fructose (which they can process directly) by expressing the enzyme invertase on the outside of their cell walls. The problem is that much of the fructose and glucose they produce floats off into the surrounding media, where it is inaccessible or worse (it could be eaten by a competitor! *Gasp!*). A group at Harvard proposed that clumped cells might have a selective advantage in a sucrose-rich media, because having a bunch of clumped cells together raises the local concentration of available fructose and glucose quite a bit. They raised single cells of yeast in a range of concentrations of sucrose and glucose, then, based on which ones grew and which didn't, backed out a model of sucrose digestion and diffusion. They added clumping to their model, and predicted that clumped yeast should be able to survive on less sucrose than the non-clumped variety. They generated some clumping yeast mutants, tried seeding *those* in sucrose media, and their predictions panned out. There are a lot of other possible reasons to start building a multicellular colony -- for instance, it makes you potentially much harder to eat -- but this is a very nice experimental exploration of one such reason. You can read the rest (for free!) here in PLOS Biology: http://ift.tt/2dZ3jG4 2) Bose is the undisputed master of the noise-cancelling headphone industry. This in itself would make a fine little TIL, but I *also* learned today that Bose *also* uses noise-cancelling tech to make super-smooth suspension for driver's seats for truckers. It turns out that taking vibration from a truck for hours and hours every day isn't very good for you, so making a driver's seat that doesn't vibrate is a big deal. 3) What the rice plant looks like. It basically looks like wheat.