Phenol/Chlo/EtOH

Ole Skovgaard olesk at RUC.DK
Fri Jun 16 07:56:06 EST 1995


In article <3recsu$qlu at ns2.sci.osaka-u.ac.jp> shiraga at gen-info.osaka-u.ac.jp (Shin-ichiro HIRAGA) writes:
>From: shiraga at gen-info.osaka-u.ac.jp (Shin-ichiro HIRAGA)
>Subject: Re: Phenol/Chlo/EtOH
>Date: 11 Jun 95 09:26:53 GMT

>One of my collaborator had same problem before. In his case, the volume of TE or H20 used for 
>suspending the dried DNA attached to the side wal of the microfuge tube. So most part of the DNA 
>recovered was left on the wall as dried.

>Although 20ul seems to enough for suspending, if the volume of EtOH ppt is much larger, the problem 
>might arise.

Not a direct answer but a hint:

The first thing I teach my students is to AVOID:

   -    Washing a pellet with - say - 70 % ethanol!
   -    Drying the pellet!

Both steps are invented by cruel biocehemsits way back in the middle age to 
prevent anybody else from succes with molecular biology!

Instead remove ALL - and I repeat: ALL - supernatant after an ethanol 
precipitation. ALL liquid is removed with a pipette at the side of the tupe 
not helding the DNA / RNA pellet.
 As no liquid is left the impurities left over are minimal and have no 
consequences for further steps.

You gain:

Less steps / faster action -> less chance of loosing DNA - especilly washing 
may remove a lot of DNA.

The semi wet pellet is much faster - and safer - to 
redissolve -> less chance to loose it in say upcomming phenol extractions.


Best luck

ole




******************************************
****   Ole Skovgaard                  ****
****   Dept. Life. Sc. & Chemistry    ****
****   Roskilde University, DK        ****
******************************************



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