Proposed studies are designed to investigate the base-specific interactions of methyl-mercuric hydroxide or other organomercurials with nucleic acids. Specifically, the proposed studies will be concerned with: 1. the investigation of the physical and chemical properties of the methylmercury complexes of nucleic acids using physico-chemical methods such as ultracentrifugation, viscosity measurements, and partial specific volume determinations. 2. the development of column- chromatographic fractionation procedures for nucleic acids and their constituents which are based on the fact that monofunctional Hg ion, imbedded in a solid matrix, reacts only with some specific binding sites of the bases of the nucleic acids. These studies are viewed as being a part of a long-term interest of the Principal Investigator in the physical and chemical properties of nucleic acids in general, with a special emphasis on those characteristics which are dependent on base composition and base distribution. In addition, it is hoped that proposed studies provide deeper insights into the reaction of certain pesticides at the molecular level.