Studium cytoskeletu a ultrastrukturální charakteristika vybraných patogenních kvasinek - Malassezia pachydermatis a Cryptococcus laurentii
| Title in English | The study of cytoskeleton and ultrastructural characteristics of chosen pathogenic yeasts - Malassezia pachydermatis and Cryptococcus laurentii |
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| Year of publication | 2007 |
| Type | Monograph |
| MU Faculty or unit | |
| Citation | |
| Description | In the present thesis, the microtubular and actin cytoskeletons, ultrastructural characteristics and morphology of two potentially pathogenic basidiomycetous yeasts Malassezia pachydermatis and Cryptococcus laurentii were investigated. At studied species, the distribution of microtubules was described in relation to nucleus position and bud development. By indirect immunofluorescence, cytoplasmic microtubules were detected in interphase and a spindle with astral microtubules was seen in M-phase. The disintegration of cytoplasmic microtubules and migration of the nucleus to the bud before mitosis were characteristic features of both basidiomycetous yeasts. To detect microtubules in Malassezia pachydermatis cells, a prolonged incubation with lysing enzymes was necessary. The visualisation of F-actin structures in Malassezia pachydermatis cells by fluorescence microscopy, using both monoclonal anti-actin antibody and rhodamine-phalloidin, failed. However, actin was detected by electron microscopy with immunogold labelling. Clusters of gold particles indicating actin structures were detected mainly at the plasma membrane. A possible association of the actin cytoskeleton with unique cortical features characteristic of the genus Malassezia was suggested. The detection of actin cytoskeleton in an encapsulated strain of Cryptococcus laurentii by rhodamine-phalloidin was not successful. A possible explanation is a potential non-specific interaction of rhodamine-phalloidin with capsular polysaccharides. Using indirect immunofluorescence, actin patches were demonstrated in encapsulated strain cells. During budding, they were accumulated in growing bud and after nuclear division, they occurred at the budding base. The distribution of F-actin structures during the cell cycle of an acapsular strain Cryptococcus laurentii was described. The absence of a capsule was confirmed by India ink staining and by ruthenium red staining in ultrathin sections. Using rhodamine-phalloidin, all structures typical of yeast cells were observed, i.e., actin patches detected in the course of whole cell cycle, actin cables extending from the mother cell to sterigma and subsequently to growing bud and cytokinetic ring during cytokinesis. The distribution of actin cytoskeleton in Cryptococcus laurentii was similar to those in Cryptococcus neoformans, but poorer. All stages of cell cycle, as detected by fluorescence microscopy, were also seen in both species at the ultrastructural level, including migration of the nucleus to the bud before mitosis. |
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