RESUMO
Sporothrix schenckii conidia were induced to germinate in varying concentrations of added calcium. Calcium had a stimulatory effect on the process and a calcium concentration of 1 mM was found to be optimal. Measurements of radioactive calcium uptake confirmed that uptake was taking place during the germination of conidia to the mycelial form of the fungus. Three calcium uptake peaks were observed, the first occurred 10 min after inoculation and the other two peaks coincided with the first 2 cycles of DNA synthesis in these cells. Ionophore A23187 and cobalt sulfate inhibited germination of S. schenckii conidia and altered the normal calcium uptake pattern in these cells. On the other hand, phorbol 12-myristate-13-acetate, a stimulator of protein kinase C (PKC) activity, stimulated germination in medium without calcium. This suggests that PKC activation might account for the germination of conidia in the absence of added calcium. The effects of increasing the calcium concentration on RNA and protein synthesis were also studied. A stimulation of RNA synthesis was found at all times tested with maximum stimulation 6 h after inoculation. A stimulation in protein synthesis was also observed but only after 12 h incubation.
