The in vivo  X mRNA

In recent years extensive studies have been made concerning the replication of ϕX RF (Knippers, Whalley, and Sinsheimer, 1969), ϕX viral DNA (Knippers, Razin, Davis, and Sinsheimer, 1969), and the ϕX specific proteins synthesized during infection (Burgess and Denhardt, 1969; Gelfand and Hayashi, 1969; Mayol and Sinsheimer, unpubl.). In contrast, ϕX messenger RNA (mRNA) has received scant experimental attention since the initial observation of Hayashi, Hayashi, and Spiegelman (1963) that the in vivo ϕX mRNA was transcribed off the complementary strand of the RF and the report of an in vivo pulse-labeled RNase-, phenol-, and detergent-resistant RNA-RF complex (Hayashi and Hayashi, 1966).