Bands in all lanes [SOUTHERN]

Shin-ichiro HIRAGA shiraga4 at
Thu Nov 2 07:16:52 EST 1995

In article <DHE0L4.L3M at>, xzhang at 
(Xiaolan Zhang) wrote:

>I am performing a genomic southern using 6 REs and DNA from 2 species.  My
>probe is a 70bp fragment from the 5' end of my cDNA which I have labeled
>by random priming.  The probe does not appear to contain repeat sequences.
>The DNA was digested well and transferred to nylon membranes.
>Hybridization at high stringency and exposure of X-ray film for 1 week was
>used.  The blots are very clean.
>My results have been consistently puzzling.  There are 8 bands ranging in
>size from 1 to 8 kb that appear in all lanes regardless of RE or specie. 
>These bands vary in intensity but are about the same as the specific
>pattern over which they are superimposed.  
>I think that if there was a contaminating DNA in the samples it would not
>yield the same bands after digestion with different REs.  I tested my
>loading buffer for contamination by running just buffer and found none. 
>There should not be so many introns covered by such a short probe.  And
>they could not all happen to have the same RE sites.  
>What could these bands be from and how can I solve this puzzle?


Mnnnn, I cannot think of a good answer. 
However, it seems that a there may be a problem in the electrophoresis step.

How about dye solution for electrophoresis? Isn't it contaminated? 

Ah, this could not be any help. Sorry.

Shin-ichiro Hiraga
Graduate Student
Laboratory of Genetics
Faculty of Science
Osaka University
Toyonaka, Osaka 560
shiraga4 at

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