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20bp ladder doesnot open fully even in 4% NuSieve - (Jan/16/2008 )

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Hello everyone.
I am working with 20bp to resolve small restriction fragments (20 to 170 bp) on 3% agarose and 4% Nusieve. However on both i am only barely able to read the ladder. I am running these gels at 100 volts for 30-35 minutes. Could this be the problem? Is it too much? By the way i have tried running all the way. The ladder only moves as an whole and does not open

-Umsumaiya-

What about loading less ladder?


QUOTE (Umsumaiya @ Jan 16 2008, 10:17 AM)
Hello everyone.
I am working with 20bp to resolve small restriction fragments (20 to 170 bp) on 3% agarose and 4% Nusieve. However on both i am only barely able to read the ladder. I am running these gels at 100 volts for 30-35 minutes. Could this be the problem? Is it too much? By the way i have tried running all the way. The ladder only moves as an whole and does not open

-dedee-

I'd try running everything at a much lower voltage and for longer. You should see better band separation.

-Bunsen Honeydew-

Has the ladder been through repeated freeze/thaw cycles? You may try heating the ladder at 65C for about 10min and see if that helps.

-Judes-

100V doesn't tell us anything without the distance between positive and negative pole. What conditions does the provider of your ladder suggest?

btw: check this topic, might help also! http://www.protocol-online.org/forums/inde...showtopic=33389

-vairus-

QUOTE (Umsumaiya @ Jan 16 2008, 08:17 AM)
Hello everyone.
I am working with 20bp to resolve small restriction fragments (20 to 170 bp) on 3% agarose and 4% Nusieve. However on both i am only barely able to read the ladder. I am running these gels at 100 volts for 30-35 minutes. Could this be the problem? Is it too much? By the way i have tried running all the way. The ladder only moves as an whole and does not open


I routinely use 20bp ladder on 15cm, 3% Agarose 1000 (Invitogen) or 3% MetaPhor (Lonza) in 0.5X TBE with no problems. I run at 150V for about 4-5 hours - this runs bromophenol blue and fragments below 100bp right off the gel so if I wanted the smaller fragments to stay on I'd run for 2.5 - 3 hours maybe.

-MTO-

The company which has supplied the ladder shows a picture in the literature acconpanying the ladder in which the ladder was run at 5V/cm for one hour on a 10 cm gel. does this mean i should run it at 5*10=50 volts for one hour

-Umsumaiya-

QUOTE (MTO @ Jan 17 2008, 07:00 PM)
QUOTE (Umsumaiya @ Jan 16 2008, 08:17 AM)
Hello everyone.
I am working with 20bp to resolve small restriction fragments (20 to 170 bp) on 3% agarose and 4% Nusieve. However on both i am only barely able to read the ladder. I am running these gels at 100 volts for 30-35 minutes. Could this be the problem? Is it too much? By the way i have tried running all the way. The ladder only moves as an whole and does not open


I routinely use 20bp ladder on 15cm, 3% Agarose 1000 (Invitogen) or 3% MetaPhor (Lonza) in 0.5X TBE with no problems. I run at 150V for about 4-5 hours - this runs bromophenol blue and fragments below 100bp right off the gel so if I wanted the smaller fragments to stay on I'd run for 2.5 - 3 hours maybe.

ok i'l try running it for 2-3 hours. We are used to running our 1.5% agarose gels at 100V for 30 minutes!
By the way Isn't 150V too high. Some students have complined of their gels melting at high voltages

-Umsumaiya-

QUOTE (Judes @ Jan 16 2008, 11:43 PM)
Has the ladder been through repeated freeze/thaw cycles? You may try heating the ladder at 65C for about 10min and see if that helps.


Very interesting. do you suggest i keep my ladder at RT or in the fridge rather than freezer (-20) I had the impression heating it would damage it somehow

-Umsumaiya-

QUOTE (dedee @ Jan 16 2008, 09:03 PM)
What about loading less ladder?


QUOTE (Umsumaiya @ Jan 16 2008, 10:17 AM)
Hello everyone.
I am working with 20bp to resolve small restriction fragments (20 to 170 bp) on 3% agarose and 4% Nusieve. However on both i am only barely able to read the ladder. I am running these gels at 100 volts for 30-35 minutes. Could this be the problem? Is it too much? By the way i have tried running all the way. The ladder only moves as an whole and does not open


tried that. same results

-Umsumaiya-

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