Our basic cell biology research was aimed at investigating the effect on eukaryotic cells of the sudden loss of the F-actin cytoskeleton. Cells treated with latrunculin A (LA) in yeast extract peptone dextrose (YEPD) medium were examined using phase-contrast and fluorescent microscopy, freeze-substitution, transmission and scanning electron microscopy, counted using a Bürker chamber and their absorbance measured. The cells responded to the presence of LA, an F-actin inhibitor, with the disappearance of actin patches, actin cables and actin rings. This resulted in the formation of larger spherical cells with irregular morphology in the cell walls and ultrastructural disorder of the cell organelles and secretory vesicles. Instead of buds, LA-inhibited cells formed only 'table-mountain-like' wide flattened swellings without apical growth with a thinner glucan cell-wall layer containing β-1,3-glucan microfibrils. The LA-inhibited cells lysed. Actin cables and patches were required for bud formation and bud growth. In addition, actin patches were required for the formation of β-1,3-glucan microfibrils in the bud cell wall. LA has fungistatic, fungicidal and fungilytic effects on the budding yeast Saccharomyces cerevisiae.

• MeSH
• aktiny antagonisté a inhibitory   MeSH
• antifungální látky farmakologie   MeSH
• bicyklické sloučeniny heterocyklické farmakologie   MeSH
• mikrobiální viabilita účinky léků   MeSH
• mikroskopie MeSH
• počet mikrobiálních kolonií MeSH
• Saccharomyces cerevisiae cytologie   účinky léků   fyziologie   MeSH
• Saccharomycetales cytologie   účinky léků   fyziologie   MeSH
• thiazolidiny farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: This basic research aimed to investigate the effects of the actin inhibitor latrunculin A (LA) on the human pathogen Cryptococcus neoformans, by freeze-substitution (FS) and electron microscopy (EM), to determine whether the actin cytoskeleton can become a new antifungal target for inhibition of cell division. METHODS: Cells treated with LA for 20 h in yeast-extract peptone dextrose medium were investigated by phase-contrast and fluorescent microscopy, FS and transmission EM, counted in a Bürker chamber and the absorbance was then measured. RESULTS: The disappearance of actin patches, actin cables and actin rings demonstrated the response of the cells of C. neoformans to the presence of the actin inhibitor LA. The removal of actin cables and patches arrested proliferation and led to the production of cells that had ultrastructural disorder, irregular morphology of the mitochondria and thick aberrant cell walls. Budding cells lysed in the buds and septa. CONCLUSION: LA exerts fungistatic, fungicidal and fungilytic effects on the human pathogenic yeast C. neoformans.

• MeSH
• aktiny antagonisté a inhibitory   MeSH
• antifungální látky farmakologie   MeSH
• bicyklické sloučeniny heterocyklické farmakologie   MeSH
• buněčná stěna účinky léků   metabolismus   MeSH
• buněčné dělení účinky léků   MeSH
• Cryptococcus neoformans účinky léků   metabolismus   MeSH
• elektronová mikroskopie metody   MeSH
• fluorescenční mikroskopie metody   MeSH
• kryptokokóza farmakoterapie   metabolismus   mikrobiologie   MeSH
• lidé MeSH
• mikrofilamenta účinky léků   metabolismus   MeSH
• proliferace buněk účinky léků   MeSH
• thiazolidiny farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The F-actin cytoskeleton of Cryptococcus neoformans is known to comprise actin cables, cortical patches and cytokinetic ring. Here, we describe a new F-actin structure in fungi, a perinuclear F-actin collar ring around the cell nucleus, by fluorescent microscopic imaging of rhodamine phalloidin-stained F-actin. Perinuclear F-actin rings form in Cryptococcus neoformans treated with the microtubule inhibitor Nocodazole or with the drug solvent dimethyl sulfoxide (DMSO) or grown in yeast extract peptone dextrose (YEPD) medium, but they are absent in cells treated with Latrunculin A. Perinuclear F-actin rings may function as 'funicular cabin' for the cell nucleus, and actin cables as intracellular 'funicular' suspending nucleus in the central position in the cell and moving nucleus along the polarity axis along actin cables.

• MeSH
• aktiny analýza   MeSH
• bicyklické sloučeniny heterocyklické farmakologie   MeSH
• buněčné jádro ultrastruktura   MeSH
• Cryptococcus neoformans účinky léků   fyziologie   ultrastruktura   MeSH
• dimethylsulfoxid farmakologie   MeSH
• elektronová mikroskopie MeSH
• faloidin analogy a deriváty   MeSH
• fluorescenční mikroskopie MeSH
• mikrofilamenta ultrastruktura   MeSH
• mikrotubuly účinky léků   MeSH
• modulátory tubulinu farmakologie   MeSH
• mořské toxiny farmakologie   MeSH
• nokodazol farmakologie   MeSH
• rhodaminy MeSH
• scavengery volných radikálů farmakologie   MeSH
• thiazolidiny farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The unique long-neck yeast Fellomyces fuzhouensis has F-actin cables and cortical patches. Here, we describe a new F-actin structure present in fungi, a perinuclear F-actin collar ring around the cell nucleus. This F-actin structure can be visualized by fluorescent microscopic imaging of rhodamine-phalloidin-stained F-actin in cells treated with the mitotic drug isopropyl N-(3-chlorophenyl) carbamate or the microtubule inhibitor thiabendazol or when cells were grown in cut dried radish medium or yeast extract pepton dextrose (YEPD) medium. In contrast, these structures were absent in cells treated with Latrunculin A. The hypothetical functions of the F-actin ring are discussed.

• MeSH
• aktiny metabolismus   MeSH
• Basidiomycota účinky léků   růst a vývoj   metabolismus   ultrastruktura   MeSH
• bicyklické sloučeniny heterocyklické farmakologie   MeSH
• buněčné jádro metabolismus   MeSH
• fluorescenční mikroskopie MeSH
• mikrofilamenta metabolismus   ultrastruktura   MeSH
• thiazolidiny farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Temperature-sensitive actin mutant of Saccharomyces cerevisiae act1-1 was studied at a permissive temperature of 23°C by light, fluorescent and electron microscopy to elucidate the roles of actin cytoskeleton in the cycling eukaryotic cells. Mutant cells that grew slowly at the permissive temperature showed aberrations in the cytoskeleton and cell cycle. Mutant cells contained aberrant 'faint actin cables,' that failed in directing of mitochondria, vacuoles and secretory vesicles to the bud and the stray vesicles delivered their content to the mother wall instead of the bud. Bud growth was delayed. Spindle pole bodies and cytoplasmic microtubules did not direct to the bud, and nucleus failed to migrate to the bud. Repeated nuclear divisions produced multinucleated cells, indicating continued cycling of actin mutant cells that failed in the morphogenetic checkpoint, the spindle position checkpoint and cytokinesis. Thus, a single actin mutation appears to indicate uncoupling in space and time of the 'actin cytoskeleton-dependent cytoplasmic pathway of bud development and organelle positioning and inheritance' from the 'microtubule-dependent nuclear division pathway' in a budding yeast cell cycle.

• MeSH
• aktiny genetika   metabolismus   ultrastruktura   MeSH
• aparát dělícího vřeténka genetika   metabolismus   MeSH
• buněčné dělení MeSH
• cytoplazma metabolismus   MeSH
• fluorescenční mikroskopie metody   MeSH
• mikrofilamenta genetika   metabolismus   ultrastruktura   MeSH
• mikroskopie elektronová rastrovací transmisní metody   MeSH
• mikroskopie elektronová rastrovací metody   MeSH
• mikrotubuly genetika   metabolismus   ultrastruktura   MeSH
• mutace MeSH
• Saccharomyces cerevisiae genetika   růst a vývoj   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND: The aim of this basic study was to investigate by scanning electron microscopy the effects of cytoskeleton inhibitors on conidiogenesis and capsule in the yeast Fellomyces fuzhouensis CBS 8243, related to Cryptococcus neoformans. METHODS: Cells were treated by methyl benzimidazole-2-ylcarbamate (BCM) and latrunculin A (LAT) in yeast extract peptone dextrose medium and examined by scanning electron microscopy. RESULTS: During conidiogenesis, mother cells covered by capsule formed hypha-like stalks and at the hyphal tip yeast-like conidium developed. LAT blocked both stages of conidiogenesis. Inhibited mother cells and conidia became spherical and their capsule disappeared. BCM did not block formation of conidia that were neckless, or affect capsule. Combined application of LAT and BCM blocked both stages of conidiogenesis, cells became spherical and their capsule disappeared. CONCLUSION: Yeast cells with disrupted actin cytoskeleton do not reproduce by conidiogenesis and do not retain inherited cell shape and capsule.

• MeSH
• Basidiomycota účinky léků   ultrastruktura   MeSH
• bicyklické sloučeniny heterocyklické farmakologie   MeSH
• cytoskelet účinky léků   ultrastruktura   MeSH
• mikroskopie elektronová rastrovací metody   MeSH
• spory hub účinky léků   ultrastruktura   MeSH
• thiazolidiny farmakologie   MeSH
• tvar buňky účinky léků   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH