FIG. 7.

Poly(U)-tailed NA mRNA is predominantly localized in the nucleus. Cells infected with the A₆ mutant (A to C and J to L) or wild-type (D to F and M to O) virus and mock-infected cells (G to I and P to R) were hybridized with NA mRNA-specific (A to I) or poly(U)-tailed NA mRNA-specific (J to R) probes. Nuclei of cells were stained with DAPI (left column). The distribution of the corresponding probe was visualized by fluorescence microscopy with FITC (middle column). The right column consists of the merged images of the other two columns. Note that not all the cells were infected with virus.