Observation of sporulating aerial hyphae by phase contrast, fluorescence and electron microscopy. (A) Abnormal branches at the aerial hyphae of the mutant observed by contrast microscopy. The ΔcmdB and ΔcmdA-F mutants frequently produced multiple branches in aerial hyphae, both low in the hyphae (indicated by white arrows), and near the tips (black arrows). These are not common in the wide-type M145. Size bars correspond to 5 μm. (B) Observation of spores in M145 and null mutants of cmdB or cmdA-F under scanning electron microscopy. Strains were inoculated on MS medium covered with cellophane at 30°C for 7 days. Samples were treated (Materials and methods) and subjected to SEM observation. The collapsed aerial hyphae and short spore chains are indicated by white arrows. (C) Chromosomes in the aerial hyphae were stained by DAPI, and observed by laser-scanning confocal microscopy. The chromosomes were not normally segregated in some of the pre-spores of the mutants, some compartments receiving none and some containing more than one chromosome (indicated by white arrows).