The technique of microinjection along with viral genetics and molecular biology has proven useful in the correlation of retroviral polynucleotide structure with function. The advantage of this technique is the involvement of living cells where rare activities may be observed and where properties of living cells can be assayed. Future studies involving recombinant DNA molecules and the asso- ciation of proteins with nucleic acids promise to yield additional insight into the nucleotide sequences involved in the expression of viral activities. References Anderson SM, Chen JH (1981) In vitro translation of avian myeloblastosis virus RNA. J Virol 40: 107-117 Berget SM, Moore C, Sharp PA (1977) Spliced segments of the 5' terminus of adenovirus 2 late mRNA. Proc Nat! Acad Sci USA 74:3171-3175 Bishop JM (1978) Retroviruses. Annu Rev Biochem 47:35-88 Capecchi MR (1980) High efficiency transformation by direct microinjection of DNA into cultured mammalian cells. Cell 22:479-488 Chien, Y-H, Junghans RP, Davidson W (1980) Electron microscopic analysis of the structure of RNA tumor virus nucleic acids. In: Stephenson JR (ed) Molecular biology of RNA tumor viruses.
