Shear-induced assembly of lambda-phage DNA.

Recombinant DNA technology, which is based on the assembly of DNA fragments, forms the backbone of biological and biomedical research. Here we demonstrate that a uniform shear flow can induce and control the assembly of lambda-phage DNA molecules: increasing shear rates form integral DNA multimers of increasing molecular weight. Spontaneous assembly and grouping of end-blunted lambda-phage DNA molecules are negligible. It is suggested that shear-induced DNA assembly is caused by increasing the probability of contact between molecules and by stretching the molecules, which exposes the cohesive ends of the otherwise undeformed lambda-phage DNA molecules. We apply this principle to enhance the kinetics and extent of DNA concatenation in the presence of ligase. This novel approach to controlled DNA assembly could form the basis for improved approaches to gene-chip and recombinant DNA technologies and provide new insight into the rheology of associating polymers.