But now a rise in temperature was followed 40 minutes later by a rise in oxygen, not a drop. They periodically raised and lowered both the oxygen levels and the temperature in flasks of E. To test that possibility, the scientists turned E. coli has to switch to a low-oxygen program whenever it defends itself against high temperatures.
Unless the oxygen is going to drop soon, this would be a disastrous decision. coli is bathing in a broth rich in oxygen. This switch is remarkable when you consider that it can happen while E. coli gets warm, it not only switches on heat-defense genes, but also starts making the switch to low-oxygen genes. coli, keeping careful track of which genes were turned on and off when they tweaked the temperature and oxygen levels. To find out, they experimented on some E. coli might use it as a cue to start to prepare for the change. coli has to shut down the network of genes it uses to metabolize sugar with the help of oxygen, and then switch on hundreds of other genes for feeding without oxygen.Ī sudden rise in temperature is a reliable signal that oxygen will start to drop over the next few hours. Later, as it moves from your mouth down through your gut, the level of oxygen in its environment will drop to near zero. It immediately gets a lot warmer, for one thing. coli that’s just arrived in your mouth, the world begins to change. Just remember, don’t eat raw cookie dough!) For the E. (Fortunately, the vast majority of these bacteria are totally harmless. coli carried from your hands to your mouth. The Princeton scientists started by considering E. It may not have a brain made up of billions of cells, but it does have a complex network of genes that might be able to use information to make predictions about things to come. (Think of Pavlov’s dogs, drooling at the sound of the dinner bell.) That led scientists at Princeton to wonder whether E. In fact, thanks to our brains, we can learn new signals. So-called “higher” species, like us, can also respond to signals of things to come.
coli is responding to something that’s already present in its environment. coli producing a lot of lactose-digesting proteins.
Microcosm carl zimmer series#
If it should encounter lactose, however, the sugar molecule can pull away the repressing proteins, initiating a series of events that leads to E. But most of the time, it keeps the genes for those proteins shut down. coli can make proteins that allow it to feed on lactose, the sugar in milk. coli‘s genes switch on and off is well-suited to its particular kind of life. In later years, scientists discovered this basic on-off strategy at work (with lots of variations, of course) in the DNA of all living things. One of the most important chapters in the history of modern biology was the discovery of these switches in E.
(Likewise, other proteins can clamp onto other stretches of DNA and speed up the reading of genes as well.) When those proteins fall off, or are pried away, the genes can be switched on. Proteins can clamp onto stretches of DNA near certain genes, for example, making it impossible for the microbe to read them and make the corresponding proteins. coli turns some genes on and keeps others turned off, a bit like playing the keys of a piano. That would not only be a spectacular waste of energy. But it does not use all those genes to make proteins and RNA molecules all at once. coli has 4000-odd genes, which it can use in various combinations to meet the many challenges it faces. It may even be able to predict the future.Į. Yet I may have underestimated the brainless intelligence of E. It can build microbial cities out of goo, and even commit suicide to help its fellow E. It can survive starvation by folding its DNA into a crystalline sandwich and powering down for months, even years in some cases. It can protect itself from overheating by making just enough protective proteins it needs, with thermostat-like precision. It can navigate away from the bad and towards the good. It can can build intricate tails which it can then spin hundreds of times a second in order to swim. It can survive in frozen soils and stomach acid. In my book Microcosm (which has just come out in paperback), I took great pleasure in all the things that something as tiny as E.
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