Filter replicas and permanent collections of recombinant DNA plasmids

A permanent, ordered collection of 23,000 recombinant DNA plasmids containing Drosophila melanoqaster DNA has been established. Simple and practical methods for storing and manipulating this collection were developed. In addition, an improved, simple and Inexpensive method for making paper filter replicas of such an ordered collection and of a high density (10,000 colonies/petri dish) unordered collection was developed. These filter replicas are suitable for nucleic add hybridization screens of recombinant DNA colonies and each filter replica can be used for many (≥5) successive screens. The kinetics of this hybridization reaction were examined and allow design of experiments that detect colony complementarity to a nucleic acid that is 0.5% of the hybridization probe.