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From: chiaraviglio@husc4.HARVARD.EDU (lucius)
Newsgroups: sci.bio
Subject: Re: Life Classification ...further comments
Message-ID: <2207@husc6.UUCP>
Date: Fri, 5-Jun-87 19:22:19 EDT
Article-I.D.: husc6.2207
Posted: Fri Jun  5 19:22:19 1987
Date-Received: Wed, 10-Jun-87 01:02:59 EDT
References: <9543@duke.cs.duke.edu> <1125@ius2.cs.cmu.edu> <701@edge.UUCP> <1211@sigi.Colorado.EDU> <1105@aecom.YU.EDU> <105@bernina.UUCP>
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Reply-To: lucius%tardis@harvard.harvard.edu (lucius)
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Summary: You don't need to wait -- I've done it without the wait, and it works.

In article <105@bernina.UUCP> srp@bernina.UUCP (Scott Presnell) writes:
>The technique

	I presume you mean the Hexamine Cobalt Chloride procedure?

>              does have the advantage of being a one-day procedure,
>whereas there is a 24 Hr. wait for the CaCl2 procedure (for competency to
>set in).

	I have run K38 E. Coli (which are HfrC Lamda-Lysogen, but otherwise
wild-type, and give trashy transformation efficiency in general) through the
cold CaCl[2] procedure for inducing competence and transformed them almost
immediately after doing this and they are competent.  You have to plate a load
of them to get a reasonable number of colonies, but waiting a day or more
neither helps nor hurts.  (I was doing this because I had been told that even
though freezing didn't kill them it robbed them of their competency over a
short time in frozen storage, but this seems to be wrong or at least
exaggerated.)  Supposedly the freezing process increases the competency of
some strains, but I have never tested this.

	Anyway, if you're in a hurry and using the CaCl[2] procedure, don't
bother to wait 24 hours.  If you have a strain that you know is helped by the
freezing, just dump them in the liquid nitrogen and then thaw them out and use
them right then.

	-- Lucius Chiaraviglio
	   lucius%tardis@harvard.harvard.edu
	   seismo!tardis.harvard.edu!lucius