Ahad, 11 Mei 2008

Oh poo! Replication of chemostat E coli

Dirty diapers and the beginnings of life

[Random selections from Carl Zimmer's blog The Loom]

"If you type in "Escherichia coli" into PubMed, the search engine for the National Library of Medicine, you get 253,128 scientific papers. Today millions of diabetics get their insulin from E. coli that carry human insulin genes.

So you might think there must have been some eminently rational plan to select E. coli to become the creature science knows best. But there wasn't. It was discovered by Theodor Escherich, a pediatrician. In 1885 he delivered a lecture announcing the discovery of a rod-shaped microbe in the diapers of healthy babies. He was struck by how fast it grew on all sorts of food--milk, potatoes, blood. Scientists in the early 1900s used it to study metabolism, but they also used a lot of other bacteria. It was one among many.

As the French E. coli biologist Jacques Monod declared, what is true for E. coli is true for the elephant (regarding reproduction)".

Larry Moran at Sandwalk blog: Carl Zimmer is among the very best—possibly the best—of the modern science writers. His new book Microcosm: E. coli and the New Science of Life is going to be on sale May 6, 2008. I was mildly disappointed to see Carl repeat a common myth about DNA replication in E. coli on page 29.


Larry: Here's the problem. How can E. coli divide faster than it can replicate it's chromosome?

Me: (Probably completely wrong, since it's purely guessing) light-dark cycle as a factor in replication timing, ability to speed up dependent on if light-dark cycle is speeded up? The thing is, of course the light-dark cycle (diurnal-nocturnal, day-night) can't directly affect the gut bacteria, since they are inside the body. But is there a clock which synchronizes the GI tract according to a) body temp = activity, b) glandular secretion / biochemical stimulation via the eyes, skin, transparent fingernails etc.? Well I just wanted to throw that in at his blog comments.


Here's Larry's solution: http://sandwalk.blogspot.com/2008/05/dna-replication-in-e-coli-solution.html?showComment=1210535040000

It seems to me to be a tidal phenomenon, waves of replication of DNA daughters, making new ones before the old ones have fully separated, in the same way waves at the seashore will overlap one another. Well, that's cool, tidal is cooler than temporal clocks, possibly being subjective to solunar effects hypothetically. I'd like to know the wavelength and frequency of these waves, and compare to heart rate and oceanic waves, might be a correlation there.

Carl's post-operative articles at his blog, the loom, scroll down to see his top 5 questions about E coli and his book Microcosm:

and his honest admission of his booboo: "Meanwhile, Larry Moran is going over the book with a fine-tooth comb and catching at least one mistake. Ouch. I knew I should have been more careful about how fast chromosomes replicate. Something to fix in the next printing..."

coolness for any biofreaks, right? hehe. Nature rules people's stools! ahaks.

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