ABSTRACT
We have developed a procedure for the resolution of restriction enzyme digests of mammalian genomic DNA in two dimensions. Fragments from a first digestion are separated on a column of purified agarose containing a second restriction enzyme in the absence of the divalent cation required for enzyme activity. After enzyme activation and digestion, the fragments are resolved on an agarose slab gel. We have digested rat genomic DNA and found in the ethidium-stained pattern a variety of features which have not been described previously.
Subject(s)
DNA/analysis , Genes , Animals , DNA Restriction Enzymes , Deoxyribonuclease BamHI , Deoxyribonuclease EcoRI , Deoxyribonuclease HindIII , Electrophoresis, Agar Gel , RatsABSTRACT
Gel electrophoretic analysis has been used to study some of the conformational properties of 18 S rRNA from HeLa cells. After isolation and treatment by heat or denaturants, the mobility of the RNA in 3% acrylamide/0.5% agarose composite gels was found to be altered; often there were two or more distinct components. Several of these forms could be interconverted by heating to 40 degrees C or by use of dimethyl sulfoxide. Although these comformers were easily distinguishable (by their electrophoretic properties), their melting profiles were very similar. Only a single electrophoretic form was detected when electrophoresis was performed at 40 degrees C. The conformational differences observed are probably derived by variations in base pairing and stacking that result when the parent form is cooled.
