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. 2011 Apr;10(4):611–615. doi: 10.1128/EC.00315-10

Fig. 2.

Fig. 2.

DArasA1 expression causes loss of polarized growth axes, hyphal swelling, vacuolization, and spontaneous lysis. (A) The wild-type (WT) and DArasA1 strains were grown for 12 h and stained with calcofluor white (CFW) and propidium iodide (PI) to visualize the cell wall and nuclei, respectively. Staining and microscopy were performed as previously described (4). (Panel i) Wild-type A.fumigatus, displaying a normal distribution of nuclei throughout the hyphae and accompanied by minimal swelling of the initial conidiospore (arrows denote septa). (Panel ii) Hyperswollen DArasA1 conidiospore with increased nuclear content. (Panel iii) Nascent DArasA1 germling, showing normal distribution of nuclei (arrowheads) along the germ tube. (Panel iv) DArasA1 hyphae with normal nuclear distribution among hyphal compartments delineated by septa (arrows). (Panel v) Mature DArasA1 hyphae with swollen subapical compartments and increased nuclear content (arrows denote septa). (Panel vi) Aborted polarized growth axes in the DArasA1 mutant with swollen germ tube. (B) Conidia of strain DArasA1 were preincubated in glucose minimal medium (GMM) at 37°C for 4 h in 6-well, glass-bottom tissue culture plates. Following preincubation, plates were used for live-cell analysis performed with an Inverted Zeiss Axio Observer microscope equipped with a 37°C environmental chamber. The time stamp values displayed for live-cell movies and still-frame images represent minutes:seconds of the postpreincubation period. The scale bar displayed in the live-cell movies in the supplemental material represents 50 μM. (Panels i to iii) Still-frame images of a DArasA1 abortive-growth axis from movie S2 in the supplemental material. The arrowheads follow the position of the hyphal tip, which ceased polarized extension after the time point represented by panel ii and reentered isotropic growth coupled with vacuolar expansion, as shown in panel iii. (Panels iv to vi) Still-frame images of spontaneous lysis of hyphal compartments (arrowheads) in the DArasA1 strain from movie S2 in the supplemental material. Arrowheads indicate ruptured compartments with released cellular debris.