“Miracle,” “miraculously” used to describe reassembled … bacteria
|November 9, 2013||Posted by News under Intelligent Design, News, Cell biology|
Here in our combox, bornagain77 notes a very interesting find, “Lazarus” bacteria”*:
If its naming had followed, rather than preceded, molecular analyses of its DNA, the extremophile bacterium Deinococcus radiodurans might have been called Lazarus. After shattering of its 3.2 Mb genome into 20–30 kb pieces by desiccation or a high dose of ionizing radiation, D. radiodurans miraculously reassembles its genome such that only 3 hr later fully reconstituted nonrearranged chromosomes are present, and the cells carry on, alive as normal. In its ability to repair severe DNA damage, D. radiodurans is similar to several bacterial species (Cox and Batista, 2005) and the bdelloid rotifers (Gladyshev and Meselson, 2008), which also periodically contend with the DNA-shattering effects of desiccation. In this issue of Cell, Slade et al. (2009) provide the most comprehensive picture to date of how such miracles are wrought.
D. radiodurans cells are more than 200 times better able to repair and survive DNA breakage than Escherichia coli, which by comparison has a moderate capacity for repair (Cox and Batista, 2005 and references therein). Some of the prowess for repair displayed by D. radiodurans may result from having more complementary or homologous DNA fragments to engage as repair partners. Whereas E. coli carries 1–4 identical chromosomes per cell, D. radiodurans carries 4–10 copies of its two chromosomes per cell. Beyond this difference, the steps of repair in D. radiodurans appear to be conspicuously normal.
“Miracles?” “Miraculously?” Well, we can’t rule out that it is a miracle, of course, but perhaps there is a layer of organization in a life form that is more basic than DNA as we know it. Perhaps it provides information that enables the DNA to reassemble correctly. Having more identical chromosomes won’t necessarily account for the observation if those chronmosomes don’t know what to do either. And if they know, how do they?
Note: This article is NIH Public Access. That terminology might have been stuck from the version that appeared in Cell, but we’d have to pay to find out.
* The term has nothing to do with “Lazarus species”: Those are species ruled extinct that turn up again decades later. Their demise, like Mark Twain’s, was greatly exaggerated …