| Citation | R.A. Laskey's most important contributions concern chromatin assembly, DNA replication, and fluorography. He was the first to assemble purified DNA in vitro into a chromatin structure having the normal 200 base pair spacing of nucleosomes. In the course of this work, he discovered, purified, and characterized nucleoplasmin; this is a major component of vertebrate nucleoplasm which assembles nucleosomes from histones and DNA in vitro. His investigations of DNA synthesis, with R.M. Harland, have established the novel concept that eukaryotic DNA can initiate replication at random DNA sequences, but can still replicate each region only once in each cell cycle. Lastly, he discovered (with W.M. Bonner), and subsequently extended, fluorographic methods of detecting radioisotopes with greatly increased sensitivity. These procedures have found widespread application in cell biology, enabling 3H-compounds to be detected in polyacrylamide or agarose gels and increasing the sensitivity of detection of other isotopes. The overall direction of R.A. Laskey's work, which has mainly been on amphibian oocytes and eggs, has been towards the analysis of gene activity and chromosome replication in early animal development, though the results have often been of direct relevance to other fields. |