Howard Temin and David Baltimore independently discover the enzyme reverse transcriptase in RNA viruses. se uses RNA as a template to synthesize a single-stranded DNA complement. This process establishes a pathway for genetic information flow from RNA to DNA. With Dulbecco, Baltimore and Temin are awarded the Nobel Prize in Medicine or Physiology in 1975.
Baltimore, D. 1970. Viral RNA-dependent DNA polymerase. Nature 226: 1209-1211. In Microbiology: A Centenary Perspective, edited by Wolfgang K. Joklik, ASM Press. 1999, p.518 [pdf]
Temin, H. M. and S. Mizutani. 1970. RNA-dependent DNA polymerase in virions of Rous carcinoma virus. Nature 226: 1211-1213. In Microbiology: A Centenary Perspective, edited by Wolfgang K. Joklik, ASM Press. 1999, p.522 [pdf]