Roles of Ca2+ in hyphal and yeast-form growth inCandida albicans. Growth regulation by altered extracellular and intracellular free Ca2+ concentrations
- 42 Downloads
The dimorphic fungusCandida albicans has both a yeast form and a hyphal form. When yeast-form cells were starved and then transferred to aN-acetylglucosamine medium, the formation of true hyphae from the unbudded yeast-form cells was induced. Removal of Ca2+ from the medium with EGTA inhibited hyphal formation by 50%, resulting in only thin and short hyphae. Externally applied excess Ca2+ (>10−2M) also affected the hyphal formation, resulting in formation of pseudohyphae. This effect required a high concentration of Ca2+ but was Ca2+-specific. Deprivation of Ca2+ also inhibited yeast-form growth. Interestingly, such cells had abnormally wide bud necks and became defective in cell separation. To measure cytosolic free Ca2+, fura-2 was introduced into hyphal cells by electroporation. Its normal value was estimated to be about 100 nM. The electroporation caused transient elevation of cytosolic free Ca2+ concentration and transient cessation of hyphal growth. There was a close correlation between the timing of recovery of Ca2+ concentration and that of the resumption of hyphal growth. Our results demonstrate the importance of extracellular and intracellular free Ca2+ for the growth ofC. albicans.
Key wordscalcium ion cytokinesis fura-2 probenecid tip growth
Unable to display preview. Download preview PDF.
- Campbell, A. K. 1983. Intracellular calcium: Its universal role as regulator. John Wiley & Sons, Chichester.Google Scholar
- Hepler, P. K. and Wayne, R. O. 1985. Calcium and plant development. Ann. Rev. Plant Physiol.36: 397–439.Google Scholar
- Iida, H., Yagawa, Y. and Anraku, Y. 1990b. Essential role for induced Ca2+ influx followed by [Ca2+]i rise in maintaining viability of yeast cells late in the mating pheromone response pathway. A study of [Ca2+]i in singleSaccharomyces cerevisiae cells with imaging of fura-2. J. Biol. Chem.265: 13391–13399.PubMedGoogle Scholar
- Miller, D. D., Callaham, D. A., Gross D. J. and Hepler, P. K. 1992. Free Ca2+ gradient in growing pollen tubes ofLilium. J. Cell Sci.101: 7–12.Google Scholar
- Odds, F. C. 1988. Morphogenesis inCandida, with special reference toC. albicans. In:Candida and candidiasis, (ed. by Odds, F. C.), pp. 42–59. Bailliere Tindal, London.Google Scholar
- O'Driscoll, D., Wilson, G. and Steer, M. W. 1991. Lucifer yellow and fluorescein isothiocyanate uptake by cells ofMorinda citrifolia in suspension cultures is not confined to the endocytotic pathway. J. Cell Sci.100: 237–241.Google Scholar
- Ogawa, Y. and Kitazawa, T. 1975. Sarcoplasmic reticulum. in: Methods in biochemistry 5, Muscle, (ed. by The Japanese Biochemical Society), pp. 315–337. Tokyo Kagaku Dojin, Tokyo. (In Japanese.)Google Scholar
- Oiki, S. and Okada, Y. 1987. Ca-EGTA buffer in physiological solutions. Seitai no Kagaku38: 79–83. (In Japanese.)Google Scholar
- Paranjape, V. and Datta, A. 1990. Role of calcium and calmodulin in morphogenesis ofCandida albicans. In: Calcium as an intracellular messenger in eucaryotic microbes, (ed. by O'Day, D. H.), pp. 362–374. Amer. Soc. Microbiol., Washington, DC.Google Scholar
- Sherman, F., Fink, G. R. and Hicks, J. B. 1986. Laboratory course manual for methods in yeast genetics, pp. 163–167. Cold Spring Harbor Laboratory, Cold Spring Harbor.Google Scholar
- Wright, K. M., Davies, T. G. E., Steele, S. H., Leigh, R. A. and Oparka, K. J. 1992. Development of a probenecid-sensitive lucifer yellow transport system in vacuolating oat aleurone protoplasts. J. Cell Sci.102: 133–139.Google Scholar