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From: eddy@boulder.Colorado.EDU (Sean Eddy)
Newsgroups: sci.bio
Subject: Re: Life Classification ...further comments
Message-ID: <1342@sigi.Colorado.EDU>
Date: Thu, 11-Jun-87 10:44:51 EDT
Article-I.D.: sigi.1342
Posted: Thu Jun 11 10:44:51 1987
Date-Received: Sat, 20-Jun-87 09:17:17 EDT
References: <9543@duke.cs.duke.edu> <1125@ius2.cs.cmu.edu>
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Reply-To: eddy@boulder.Colorado.EDU (Sean Eddy)
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In article <394@uhnix2.UUCP> bchso@uhnix2.UUCP (Dan Davison) writes:
>In <1247@sigi.Colorado.EDU> eddy@boulder.Colorado.EDU (Sean Eddy) writes:
>This list reads like the one from Levinthal, Ann. Rev. Microbiology 28:219-
>230 1974.  Is it?  Or is it updated?

No, the first thing I laid my hands on was a CRC Handbook of Microbiology.

>Gee, Sean, I consider this a handful.  But this is a difference in
>philosophy, since the mammalian cell culture transformation you cite
>would never be the same transformation as bacterial, *to me*.

Why not? I don't mean 'growth transformation' or 'neoplastic
transformation', I'm just referring to the uptake and integration
of exogenous DNA fragments.

>>And E. coli certainly *has* been reported to undergo natural
>>transformation. 
>
>References please?

Uh-oh, can't find my notes... what I saw was an old article in Nature, and was
referenced in the CRC along with all the other genera that are
reported to undergo natural transformation.
>
>>unless I seriously misunderstood the text, [it] refers to bacteria
>>in which the mere mixing of bacterial cultures with exogenous
>>DNA fragments (usually from the same species) results in
>>uptake & integration of the exogenous DNA at some detectable
>>frequency.
> 
>This sounds a little like 'mystery transformation' from the Rhodopseudomonas.
>Doug Youvan (see this month's Scientific American, the mechanism of photo-
>synthesis) has used a technique in which you mix bacteria on a plate then
>put them in an incubator overnight (with candlelight and music) and magically
>a few days later the genes have been transferred to the recipient.  As near as
>can be figured out, last I knew, the speculation was that one of the three
>bacteria you had to add to the mix (donor, recipient, and helper) actually
>mediated the transfer.  Mixing donor and recipient together provided a nice
>negative control.  I think this was suspected to be conjugative...does anyone
>know differently?
>

No, I was just trying (clumsily, I guess) to define bacterial transformation.
In the lab, you pretreat the bacteria (make competent cells with CaCl2)
and then mix them with the DNA you want them to take up. I was
trying to say that you might call 'natural transformation' cases
in which the pretreatment is not absolutely necessary.


- Sean Eddy
- MCD Biology; U. of Colorado at Boulder; Boulder CO 80309
- eddy@boulder.colorado.EDU		!{hao,nbires}!boulder!eddy	
- 
- "Why should the government subsidize intellectual curiosity?"
-					- Ronald Reagan