DNA goggles

Lee Poulsen wpoulsen@pacbell.net
Thu, 31 Jan 2013 23:30:49 PST
On Jan 31, 2013, at 9:22 PM, Leo A. Martin wrote:
> And as for identifying organisms in mud from their DNA - How would anybody know there's
> just one organism there?

I'm not a biologist, but from what I've read and heard in talks from a few scientists I've gone to listen to, I get the impression that the field (and the techniques) are now advanced enough that they can now identify how many organisms there are in your sample and something about where they fit in the "tree of life". (I.e., certainly if they are bacteria, archaea, or eukaryotes. And probably where they are within those domains.) I've heard stories that they often find that several organisms exist, but they have no idea what they look like or how to grow or culture them. For example, they've found lifeforms by sequencing the samples of what comes up from these deep earth drilling bores. I listened to one astrobiologist describe his discovery of a new unknown life form he found by sequencing the muck that lived below the bottom of Lake Michigan and how he finally was able to culture it by discovering that rather than using oxygen, it "breathed" manganese. He was finally able to image it by using a tunable laser microscope of some kind that zeroed in on a frequency where the manganese compound it "exhaled" was transparent and the organism was not transparent. He showed us a short video where we couldn't see any cells and then suddenly when they hit the correct frequency, the cells became visible. It was pretty cool.

It's pretty amazing what the technology can do these days. 

Also, you should talk with Alan Meerow about how the sequencing *helps* in determining in what families and genera some hard-to-determine species fit into. I find from what I've read that it seems to be a great help with taxonomy rather than a replacement for it. Sure, some lifeforms don't easily fit into the standard classification schemes, but I think that is because in some of the cases, earlier taxonomist divided things into genera and species (because everything gets classified that way) that maybe shouldn't have been divided that finely (or conversely, that coarsely).

--Lee Poulsen
Pasadena, California, USA - USDA Zone 10a
Latitude 34°N, Altitude 1150 ft/350 m

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