title: Hyphal orientation of Candida albicans is regulated by a calcium-dependent mechanism.
abstract: Eukaryotic cells from fungal hyphae to neurites that grow by polarized extension must coordinate cell growth and cell orientation to enable them to exhibit growth tropisms and to respond to relevant environmental cues. Such cells generally maintain a tip-high Ca(2+) cytoplasmic gradient, which is correlated with their ability to exhibit polarized tip growth and to respond to growth-directing extracellular signals. In yeast and other fungi, the polarisome, exocyst, Arp2/3, and Spitzenkörper protein complexes collectively orchestrate tip growth and cell polarity, but it is not clear whether these molecular complexes also regulate cell orientation or whether they are influenced by cytoplasmic Ca(2+) gradients. Hyphae of the human pathogenic fungus Candida albicans reorient their growth axis in response to underlying surface topography (thigmotropism) and imposed electric fields (galvanotropism). The establishment and maintenance of directional growth in relation to these environmental cues was Ca(2+) dependent. Tropisms were attenuated in media containing low Ca(2+), or calcium-channel blockers, and in mutants where calcium channels or elements of the calcium signaling pathway were deleted. Therefore galvanotropism and thigmotropism may both be mediated by localized Ca(2+) influx at sites of polarized growth via Ca(2+) channels that are activated by appropriate environmental signals.
authors.affiliation: Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Brand
authors.forename: Scott
authors.initials: S
authors.lastname: Shanks
authors.forename: Vanessa M S
authors.initials: VM
authors.lastname: Duncan
authors.forename: Meng
authors.initials: M
authors.lastname: Yang
authors.forename: Kevin
authors.initials: K
authors.lastname: Mackenzie
authors.forename: Neil A R
authors.initials: NA
authors.lastname: Gow
mesh_terms: D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002176:Candida albicans / Q000235:genetics / Q000502:physiology*; D016764:Cell Polarity / Q000502:physiology; D003593:Cytoplasm / Q000378:metabolism; D017931:DNA Primers; D004558:Electric Stimulation; D025301:Hyphae / Q000254:growth & development* / Q000378:metabolism; D016296:Mutagenesis; D015398:Signal Transduction / Q000502:physiology*; D018523:Tropism / Q000502:physiology*
chemical_list: D015220:Calcium Channels; D017931:DNA Primers; D002118:Calcium