I have a question. I need to cotransfect two plasmids: plasmid X and plasmid y According to the manufacturer's protocol for 24well plate I should take 0,5ug of DNA and 2ul of lipofectamine. Do I understand corretly that I should take 0,25ug of plasmid X DNA and 0,25ug of plasmid Y and use it with 2ul of lipofectamine? Or perhaps when i want to contransfect i I ought to use 0,5ug of EACH plasmid and 2ul of lipofectamine?
Hi Dina, total mass of DNA should be 0.5ug for every 2ul of lipofectamine. Although, you may want to play around with plasmid x:plasmid y ratio to optimise conditions to suit your experimental outcome.
Hi swelling,
Thanks a lot for your answer,
So Do you mean for example, if plasmid X is 4000 base pair and plasmid Y is 2000 base pairs, so the ration of plasmid X is half of plasmid Y?
Dear Dina, as Sweelin said, you'll have to play around with concentrations indepently of their mass, specially if they are small in size.
One plasmid might be bigger than the other but have, for instance, a stronger promoter and be more efficient in expression. It is tricky to judge plasmid efficiency from their size. In my experience, For cotransfections I start considering size-based efficiency when they are well above 8Kb assuming promoters of similar strength.
Dear sebastian,
Thanks a lot for your answer,,
In my case, I have two plasmids which are approximately equal in size ~ 5, 300 base pairs and also, they have the same promoters (Cmv), so That is mean, I add 250 ng of plasmid X and 250 ng of plasmid Y?
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