Detailed electron microscope studies on purified bacterial and viral nucleic acid (DNA and RNA) with some considerations on the relation of DNA to genetics

Abstract

DNA and RNA have been extracted and purified from bacteria (acid-fast Kedrowsky strain) and bacterial virus (Salmonella sendai phage). After confirming them to be pure both physically and chemically, their elementary fibers of DNA and RNA have been studied with the electron microscope by applying chrome shadowing. The width of single DNA fibers is about 20–25 Å and that of RNA is between 14–17 Å which coincide with the theoretical values. These fibers have also been clearly observed by electron staining with AgNO₃. With the electron microscope the author demonstrated the following facts: DNA fibers are composed of various phases of network or branch-like fashion and end in an isolated elementary fiber, and the spiral-coiled figure is most specific. RNA also demonstrated similar electron microscope figures. However, RNA has a tendency of forming a more complicated net-work of entarngled elementary fibers as compared to DNA. Interesting figures of phages revealed long processes of DNA fibers protruding from the tails of phages. Genetic studies: A transformation of DNA which controls the color production of bacteria has been successfully carried out. The interesting data has been obtained that the recombinant phages were produced when mixed infection with phages DNA and another intact phage was carried out.