FIG. 3.

Effect of substitution mutations in dr1 on ASLV replication. The results of RT assays performed on culture medium of DF1 cells transfected with 10 μg of the indicated DNAs per ml are shown. Cells were passed when confluent (twice weekly). Samples were taken immediately before passing. Error bars indicate the standard deviation of values obtained from three separate transfections with the same DNA. The large variability in the RT activity levels of the mutants may have resulted from systemic errors in the assay, given the consistency of RT activity fluctuations among the mutants.