Problems with BRL 100 bp ladder

[Burnap Lab]

In article <425rq3$pn7 at ns1.usa1.com>, suihuang at usa1.com
(suihuang at usa1.com) wrote:

> In article <416an9$fph at overload.lbl.gov>, dmh says...
> >
> >....  
> >I have been experiencing problems recently with the 100 bp ladder from
> >Gibco-BRL. ., has anyone lately
> >experienced any problems with the ladder-- particularly in certain lot
numbers?
> >Second, has anyone noticed differences in the mobility/resolution due
to added
> >NaCl?
> >Thanks in advance for your responses.
> >Derek
> >
> 
> In a reply, Christian Beltinger reported similar problems.
> 
> I also see a smear with a 100 bp ladder from Sybtrel, Inc., especially
when using 
> the more sensitive dye Sybr Green I.
> With EtBr the smear appears only when the gel was stained separately after 
> running. When using the "EtBr-in-gel-method" (put EtBr into gel before
casting), 
> no such smear is visible.
> Thus it might  be just a question of changing sensitivity, whethet the
smear is 
> visible.

Hi 
I had this problem before. Besides what is written In (Sambrook -1989
Molecular Cloning). You should do the following:
1- The lambda standard should be prepared with 25 mM NaCl.
2- Use 1% agarose gel concentration.
3- Heat your buffer (TAE or TBS) before you run your samples (you can do
that by rung the champer (sp) for 10 min at 50V).
4- If you load more than 2 ug of DNA in each well, the posibility of
having smear is high.

Suf
Ph.D. graduate Student/Oklahoma State University

E.mail sufian at osuunx.ucc.okstate.edu