BRL RNA ladder hybridizes to my probe

Ojar Melefors ojar.melefors at
Fri Aug 18 09:16:43 EST 1995

In article <DDH3B2.FEr at>, stallard at (Lana C
Stallard) wrote:

>I wonder if anyone has had this happen? I am using Gibco BRL RNA weight 
>standards (made from phage lambda DNA spliced to an RNA transcript). I get 
>significant hybridization with a mouse DNA probe (a cDNA probe of 
>angiotensin converting enzyme) to the ladder when i transfer the ladder 
>onto a Northern blot. Why would there be so much sequence similarity
between lambda and a mouse gene? or could my probe still contain some
sequences of the vector it was produces in (Bluescript 
>plasmid) which is similar to the phage DNA? My boss is convinced i have a 
>very non-specific probe but i think there must be a reason. 
>        Thanks for any comments or ideas you may have. 
>        Lana Stallard

The same thing happens to me with many of the probes I use.
I presume that just a high enough concentration of the RNA weight standard
will cause cross-hybridisation with almost any probe if the filter is not
washed stringently (same as for rRNA).
But cross hybridisation makes me happy  :-) as it facilitates the correct
determination of band sizes!


Öjar Melefors
Karolinska Institutet
"Speaking for myself"      

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