A western blot cannot be prepared from RNA. Only a protein sample can be run with a western blotting approach. The technique used to visualize RNA on a gel is called northern blotting.

It act as a buffer in Northern blotting.

yes the principle of all the three is same .the basic difference lies during probing nd detection .in case of southern blotting DNA is used in nothern rna and in case of western blotting antibodies are ued

A blad is a Scots term for a portfolio, blotting-book or blotting-pad.