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Michael Geissler

DNA ladder not showing up on agarose gel?

Antonello Frau  Follow

Pushkal Sinduvadi Ramesh, I used SYBR Safe. I do not think it is past its date and it has not been exposed to light. I did everything as dark as I could which is why I am a little confused.

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Braxton Anderson III  Follow

Hello Matthew Czmer
How much Ethidium bromide did you add? I would suggest you add at least 5uL of 10mg/mL stock EtBr for a gel cast from 50mL agarose. By looking at your gel image I feel either you have used a very low concentration of EtBr or your stock EtBr was exposed to light and lost its ability.
Hope this helps.

Best!

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Dapid Candra  Follow

When I used Sybr Safe, I used to use it at 1:10000X dilution (10ul for 100ml Agarose). In any case, the bands for Sybr Safe were always very weak compared to EtBr in a UV transilluminator (which I think you might be using?), Sybr Safe is not really excited by UV like EtBr is. You should use a blue light transilluminator for Sybr Safe.

Also, these intercalating dyes are less sensitive to single-stranded NA species, so you might have to use even more dye. I also never wait for Agarose to cool down before adding EtBr/Sybr, they are quite heat tolerant and work perfectly fine even if boiled together with the Agarose (don't do this because of spill risks).

Honestly, I feel Sybr Safe is very much overrated - EtBr is in fact less toxic than Sybr Safe and also works under blue light transillumination pretty well. It's not the EtBr that hurts your DNA when gel-extracting, it's the UV.

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Cecil Williams  Follow

Hello,
first clean the picture area in your imaging system and try a blank picture for 4s. Second may than help increasing dye concentration or try more RNA selective dye...

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