Michael Behe on Lenski’s lambda virus: “Darwinian evolution took a little step sideways and two big steps backwards.”
|January 31, 2012||Posted by News under Darwinism, News, Cell biology|
In “More from Lenski’s Lab, Still Spinning Furiously” (Evolution News & Views, January 30, 2012), Michael Behe summarizes the real discovery from a much-heralded experiment involving a virus called lambda, that infects bacteria (and is supposed to be a fast learner when it comes to infecting):
To me, the much more significant results of the new paper, although briefly mentioned, were not stressed as they deserved to be. The virus was not the only microbe evolving in the lab. The E. coli also underwent several mutations. Unlike for lambda, these were not modification-of-function mutations — they were complete loss-of-function mutations.
The mechanism the bacterium used to turn off LamB in 99% of cells to resist initial lambda infection was to mutate to destroy its own gene locus called malT, which is normally useful to the cell. After acquiring the fourth mutation the virus could potentially invade and kill all cells. However, E. coli itself then mutated to prevent this, too. It mutated by destroying some genes involved in importing the sugar mannose into the bacterium. It turns out that this “mannose permease” is used by the virus to enter the interior of the cell. In its absence, infection cannot proceed.
So at the end of the day there was left the mutated bacteriophage lambda, still incompetent to invade most E. coli cells, plus mutated E. coli, now with broken genes which remove its ability to metabolize maltose and mannose. It seems Darwinian evolution took a little step sideways and two big steps backwards.
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