Pure argF gene DNA will be ligated in vitro with an SV40 replicon and the chimeric molecule used to transform animal cells to study the expression of a prokaryotic gene in eukaryotic organisms. A DNA molecule will be constructed corresponding to the leader sequence of late adeno-2 virus mRNA. This leader sequence will be ligated to the structural region of the argF gene. This chimeric gene in turn will be recombined in vitro with an SV40 replicon and used to study the sequence requirements of eukaryotic translational machinery. Specific fragements of a type C virus and the host chromosomal integration sites will be cloned in an EK3 vector (when available). These DNA species will be utilized for biochemical studies including DNA sequence analysis. Specific fragments of some segments of the influenza virus genome will be cloned in an EK3 vector system for sequence determination and the study of gene splicing. Double stranded cDNA prepared from ovalbumin mRNA and from fragments of ovalbumin mRNA protected from RNAase digestion by mRNA-associated proteins will be cloned. The DNA sequence of these cloned molecules will be determined.