Intra-strain variability of Cryptococcus neoformans can be detected on phloxin B medium.
ABSTRACT A method was devised for easy detection of intra-strain variability of the human pathogenic yeast Cryptococcus neoformans. Cultivation of strains on a medium containing Phloxin B resulted in different coloured colonies. Generally, colonies were either pink or red; however there were also several colony-colour segregant in which both colours could be observed. A number of these segregants were isolated and analysed. Virulence factors such as the cell and capsule sizes were measured; further temperature sensitivity, growth rates, mating-types and melanin production were also studied. Segregants were examined by random amplified polymorphic DNA (RAPD) fingerprinting and electrophoretic karyotyping by pulsed-field gel electrophoresis (CHEF). They showed both phenotypic and genotypic differences. The main differences appeared in phenotypic characters and RAPD patterns; while the chromosomal patterns remained unchanged. Reversion frequency analysis revealed that the reason for this segregation could be due to phenotypic switching. The physiological reason for the colour changes was also investigated and was attributed to the differential ability of the cells to accumulate Phloxin B either into their capsules or into their cells. The method described here is potentially applicable for the detection of strain heterogeneity in both basic and clinical microbiology laboratories.
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ABSTRACT: Pulmonary infection by capsule-deficient Cryptococcus neoformans (CDCN) is a very rare form of pneumonia and it is seldom seen in the immunocompetent host. The authors experienced a case of pulmonary cryptococcosis by CDCN in 25-year-old woman who was without any significant underlying disease. The diagnosis was made from the percutaneous lung biopsy and special tissue staining, including Fontana-Masson silver (FMS) staining. Fungal culture confirmed the diagnosis afterward. Her clinical and radiologic features improved under treatment with fluconazol. It's known that CDCN is not so readily confirmed because fungal culture does not always result in growth of the organism and the empirical fungal stain is not helpful for the differentiation between CDCN and the other infections that are caused by the nonencapsulated yeast-like organisms. In this report, we emphasize the diagnostic value of performing FMS staining for differentiating a CDCN infection from the other confusing nonencapsulated yeast-like organisms.The Korean Journal of Internal Medicine 04/2006; 21(1):83-7.
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ABSTRACT: Valproic acid (VPA) inhibited the growth of yeast in a dose-dependent manner with complete inhibition attained at 100 mM. When cells were exposed to 25 mM VPA, the wild-type died showing apoptotic markers, while yca1Delta deleted of YCA1 encoding yeast caspase 1 survived. On the other hand, when cells were exposed to 50 mM VPA, both the wild-type and yca1Delta died showing morphological features similar to those of the autophagic death of cdc28 which was also independent of YCA1. Thus, these results suggested that yeast cells die via YCA1-dependent apoptosis when their proliferative activity is mildly impaired.FEBS Letters 02/2005; 579(3):723-7. · 3.58 Impact Factor
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ABSTRACT: Diferentes características fenotípicas relacionadas con la virulencia del complejo Cryptococcus neoformans han revelado su importancia en la patogenicidad. De acuerdo con estos antecedentes, se estudió fenotípicamente y genotípicamente la expresión de algunos factores de virulencia de aislamientos clínicos de las especies del complejo mencionado. Se evaluaron 35 aislamientos de C. neoformans y 19 de Cryptococcus gattii. Se estudió el crecimiento a 37 °C, la morfología macroscópica y microscópica, la frecuencia del fenómeno switching, la actividad de 23 enzimas extracelulares, la variabilidad de las colonias en medio con floxina B, la determinación del gen de la fosfolipasa B, el tipo de locus sexual mediante PCR y el patrón molecular del gen URA5 mediante RFLP. Todos los aislamientos crecieron a 37 °C. El tamaño capsular fue mayor para C. gattii (1,87 µm ±1,47 µm) que para C. neoformans (0,83 µm ±0,15 µm). El fenotipo switching se encontró principalmente en aislamientos de C. gattii. Todos los aislamientos expresaron la enzima ureasa y tenían una actividad media (Pz=0,54) en proteasas, pero C. gattii presentó una mayor actividad de la enzima fosfolipasa (Pz=0,43) y fenoloxidasa (Pz=0,003); el perfil enzimático con el API ZYM reveló una actividad baja en el 89% de los aislamientos para las dos especies. Se observaron diferencias morfológicas en medio con floxina B en el 13% de los aislamientos, de los cuales cinco eran C. neoformans y dos C. gattii. El gen de la fosfolipasa se amplificó en todos los casos. El 93% de los aislamientos de C. neoformans tenían el locus y el 47,5% de C. gattii el locus a. Predominaron los patrones moleculares VNI (82,9%) y VGII (52,6%). Se observaron diferencias en la expresión in vitro de los factores de virulencia estudiados, lo cual podría verse reflejado en estudios futuros en un modelo in vivo. Cryptococcus neoformans, Factores de virulencia, Fenotipo, In vitro In vitro determination of virulence factors activity associated with several Cryptococcus neoformans clinical isolates Different phenotypic characteristics associated with virulence of the Cryptococcus neoformans species complex have shown an important role in their pathogenicity. In this study we have determined the role of phenotypically and genotypically factors of some virulence factors from clinical isolates in the two species of the complex; 35 C. neoformans and 19 Cryptococcus gattii. Growth at 37 °C, macroscopic and microscopic morphology, switching phenomenon, activity of 23 extracellular enzymes, variability of the colonies in agar with phloxin B; phospholipase B gene, and the mating type were determined by PCR; the molecular pattern was determined by URA5 RFLP. All isolates grew at 37 °C, the capsular size was greater in C. gattii (1.87 µm ±1.47 µm) than in C. neoformans (0.83 µm ±0.15 µm). Switching was observed mainly in isolates of C. gattii. All isolates expressed the enzyme urease, a lower activity of the proteases (Pz= 0.54), but a higher activity of the phospholipase (Pz=0.43) and phenoloxidase (Pz=0.003) was determined for C. gattii.145 Rev Iberoam Micol. 01/2008; 25:145-149.