Double replica electroblotting: a method to produce two replicas from one gel

Electroblotting is a method by which proteins or nucleic acids, separated by electrophoresis, are transferred, also by electrophoresis, from a gel to a so-called transfer medium, e.g a nitrocellulose membrane. In some experiments, it is desirable to be able to obtain more than one replica from each gel and it has now proved possible to produce two replicas, which are almost identical, from one gel. This is achieved by applying one membrane on each side of the gel and change the direction of the current several times in such a way that the efficient transfer time is short in the beginning of the electroblotting and is increased for each cycle. This procedure will be referred to as 'double replica electroblotting'. Proteins were transferred at 100 V and the duration of an experiment with 2 h efficient transfer time in each direction was 7 h. The gel was more efficiently depleted of proteins after double replica electroblotting as compared to ordinary electrotransfer in one direction. Cathodically migrating proteins are also trapped on the membranes with this technique. Double replica electroblotting was used to produce two replicas from ordinary sodium dodecyl sulfate polyacrylamide gels as well as from 2-dimensional gels.