A computational procedure for the analysis of electron images of nucleic acid molecules

A new procedure is described for analyzing electron images of labeled nucleic acid molecules. The method makes use of one-dimensional digital image information and determines the best relative orientation of the linear molecules. The analysis is performed with the computer program CLUSTER, which combines the information from each molecule stepwise in an iterative procedure, so that finally a label distribution is obtained, which is the combination of all information available. The rationale behind the analysis is the calculation of similarity coefficients, which are a measure of the probability for the relative orientation of each molecule pair. The method has been thoroughly tested and compared with other procedures described in the literature in order to indicate its performance and power. A biological application concerning the distribution of the protein RNA-polymerase on DNA of phage Mu is presented.