Germ tube formation from zonal rotor fractions of Candida albicans

Abstract

Homogeneous cell populations of increasing cell volume have been isolated from exponential and stationary cultures of Candida albicans by centrifugation on a sucrose gradient. Observations of the yeast-mycelial transition using these populations showed the following. (i) No fraction from early logarithmic phase cells was able to undergo morphological transition. (ii) The time of initiation of germ tube production was correlated with cell size in stationary-phase cultures. (iii) The rate of appearance of germ tubes was nearly identical in all fractions measured. (iv) Addition of N-acetyl-D-glucosamine to homogeneous cell populations decreased the time of initial appearance of germ tubes but did not affect the rate of appearance after initiation.Candida albicans is a dimorphic fungus which can undergo transition from yeastlike growth to mycelial growth. This transition takes place in a variety of media: serum (11), complex medium (5), minimal medium (6, 7), and N-acetyl-D-glucosamine in imadazole-Mn2+ buffer (9). The synchrony or asynchrony with which cultures undergo this transition may depend both on the state of the cell at the beginning of induction of the yeast-mycelial transition and the homogeneity of the population. In the experiments reported here we have utilized zonal rotor fractionation of cell cultures to examine the effect of these two factors on yeastmycelial transition in C. albicans.Synchronous cultures ofSaccharomyces cerevisiae show a linear increase in cell size throughout the yeast cell cycle. Fractions of exponential cultures grown on minimal medium and separated by zonal rotor centrifugation also show a similar linear increase. Since cells are separated according to size and thus stage during cell cycle after zonal centrifugation, analysis of fractions from the zonal rotor should represent the properties of the cell cycle. This technique has proved successful in elucidating vegetative cell cycle events (8,10). Relationships between cell cycle stage and ability to complete meiosis and sporulation have also been determined (4). The zonal rotor has been used to fractionate logarithmically growing and stationary-phase cultures of C. albicans. The relationship between cell cycle stage and tran-I Present address: Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Mass. 02154.sition, as well as population homogeneity and synchrony, have been observed, respectively. The homogeneous fractions of cultures obtained by this method were examined for initial appearance, rate of appearance, and extent of germ tube formation. Three types of cultures were separated by zonal rotor fractionation: exponentially growing cultures on minimal medium and stationary-phase cultures grown on minimal and rich media. In addition, the effect of N-acetyl-t-glucosamine on various fractions obtained from a stationary-phase culture was observed.

Effects of low concentrations of zinc on the growth and dimorphism of Candida albicans: evidence for zinc-resistant and -sensitive pathways for mycelium formation

“…By 140 min, 50% of the released culture had formed small evaginations, and by 165 min, 50% had formed elongated germ tubes the lengths of which were one-half or more the diameters of their mother cells. of which was many times the diameter of the mother cell (3,7).…”

“…When stationary-phase cells were inoculated into fresh medium at 250C, they resumed growth in the budding yeast phase (3,7,9); however, when stationary-phase cells were inoculated into fresh medium at 37°C, they formed mycelia synchronously and en masse after an average lag period of approximately 140 min (7,9). By 140 min, 50% of the released culture had formed small evaginations, and by 165 min, 50% had formed elongated germ tubes the lengths of which were one-half or more the diameters of their mother cells.…”

Transcriptional profiling of the early stages of germination in by real-time RT-PCR

“…8. Effect of calcium inhibitors on gene expression of CGR1 (a), CaMSI3 (b), EFG1 (c), NRG1 (d), and TUP1 (e) in JCM9061 (1) and CAI4 (2). Treatment with calcium inhibitors was performed for 15 or 120 min at 37°C.…”

Effects of Culture Density on the Kinetics of Germ Tube Formation in Candida albicans

“…Early-exponential phase cultures shifted from 25 "C to 37 "C were reported to be incapable of germ tube production, whereas 100% of organisms in cultures shifted in late-exponential phase were reported to produce germ tubes (Chaffin & Sogin, 1976). Many investigators have presented additional data which support the concept that only stationary phase cells are capable of mycelial growth (Soll & Bedell, 1978;Mitchell & Soll, 1979;Bell & Chaffin, 1980).…”