Nuclear distribution in wild-type and DHC mutant strains. (A) Intermediate magnification overlay images of hyphae from wild-type and DHC mutant N. crassa strains expressing histone H1-GFP. Upward pointing arrowheads indicate the position of the nucleus closest to the hyphal tip. Bars, 50 µm. (B) Epifluorescence images of hyphae from wild-type and DHC mutant strains expressing DIC-mCherry and histone H1-GFP. (Left panels) Dynein. (Center panels) Nuclei. (Right panels) Overlay. Nuclei are absent from the extreme tips of all hyphae and appear randomly dispersed in the remainder of the hyphae in wild-type, mutant class 1, 2, 3, and 5 strains. In class 4 mutant strains, there is abnormal clustering of nuclei around the aggregate dynein foci. Bars, 10 µm.