Effects of cytochalasins onNeurospora crassa

Abstract

Growth of various strains of Neurospora crassa in the continued presence of cytochalasins A and B results in the following pattern. At low concentration the drugs cause an increase in branching which, depending on the strain, may also reveal an increase in dry weight. Increasing the concentration results in abnormal hyphae (swollen, irregular) and eventually in inhibition of growth. Most strains are inhibited at 10-20 ~xg/ml cytochalasin A. Ultrastructure of hyphae grown in the presence of cytochalasin A reveals the presence of abnormal wall deposits. These deposits are not observed in cultures grown with cytochalasin B which generally causes a lower growth response also.

Localization of RHO-4 Indicates Differential Regulation of Conidial versus Vegetative Septation in the Filamentous Fungus Neurospora crassa

“…The location of a new septum in N. crassa hyphae prior to GFP-RHO-4 localization cannot be predicted with the tools currently available. Perturbation of the F-actin cytoskeleton in CR26-9 (gfp-rho-4) hy- phae by treatment with cytochalasin-A resulted in swollen tips and "starburst"-patterned hyphae as previously reported (1,34). In DMSO-only treated samples, we observed a wide ring of GFP-RHO-4 localization at sites of imminent septation in 7% of 76 samples ( Fig.…”

What Determines Growth Direction in Fungal Hyphae?

“…Figures 6A and 6B show the results of exposing hyphae of N. crassa to filter disks impregnated with the inhibitor and placed at 1.5 cm from the margin of young colonies. Although, as previously noted, both cytochalasin (Betina et al, 1972;Allen et al, 1980;Harold and Harold, 1986) and benomyl (Richmond and Pring, 1971;Howard and Aist, 1977) induced branching, the effect we observed on hyphal morphology in N. crassa was quite different. Whereas the branches induced by cytochalasin A were mostly straight short hyphae (Fig.…”

A Fungal Kinesin Required for Organelle Motility, Hyphal Growth, and Morphogenesis

“…That polarized growth continues at all in such slow-growth mutants may indicate that apical vesicle transport in fungi involves either functionally redundant, MT-associated motor proteins (Goldstein, 1993) or redundant transport mechanisms involving different cytoskeletal components (Lillie and Brown, 1992;Barton and Goldstein, 1996), because our results suggest that there is no gene redundancy involved. Indeed, there are several lines of evidence indicating that F-actin-based transport of membranous organelles occurs in fungi (Betina et al, 1972;Allen et al, 1980;Grove and Sweigard, 1980;Novick and Botstein, 1985;Heath, 1994;McGoldrick et al, 1995). Because an actin-myosin mechanism is capable of supporting hyphal tip growth, it seems reasonable to postulate that, in the absence of either MTs or an MT-associated motor protein that is important in vesicle transport, the fungal cell will continue to grow, albeit abnormally, by utilizing the actin-based motility mechanism.…”