Role of nutritional status of the cell in pH regulated dimorphism ofCandida albicans

Abstract

Stationary phase cells of Candida albicans are under the control of glucose repression, as indicated by the inhibition of germ tube formation by glucose. This ‘glucose effect’ was absent in starved cells which were derived from similar stationary phase cells. Moreover, starved cells required glucose for germ tube formation, suggesting that it was depletion of energy reserves which was the main factor overriding the ‘glucose repression machinery’ during starvation. High concentration of phosphate in Lee's medium was the reason for the reduced ability of the starved cells to form germ tubes at pH 4.5 (20% of cells compared to 88% at pH 6.8). However, when phosphate was replaced or its concentration reduced, germ tube formation occurred as frequently at pH 4.5 as at pH 6.8. This ‘phosphate effect’ was not observed in stationary phase cells, as they were already repressed by glucose.

Cloning and sequencing of the Candida albicans homologue of SRB1/PSA1/VIG9, the essential gene encoding GDP-mannose pyrophosphorylase in Saccharomyces cerevisiae

“…The pattern of expression of the ' control ' probe in our experiments, the gene TEF3 (Swoboda et al, 1994), was consistent with published results (Swoboda et al, 1994). Since neither actin (Paranjape & Datta, 1991), nor indeed TEF3 or any other Candida gene (Swoboda et al, 1994), could be used as a classic internal loading mRNA control in this experiment, CaSRBl mRNA levels were quantified relative to the major rRNA species (see Methods).…”

Effect of Growth Media, pH and Temperature on Yeast to Hyphal Transition in <i>Candida albicans</i>

“…These growth medium were tested for observing the effect of nutrients on morphogenesis in C. albicans. The importance of nutrient factors that induce germ tube formation in C. albicans has been reported in previous papers [44][45][46][47].…”

“…Horse serum, that is natural ingredients of hemin, hormones and other blood serum constituents, appeared to be necessary for germ tube formation and hence increased pathogenicity for most C. albicans strains [23,45,48]. We observed noticeably increased filamentation in horse serum (Figure 1) about 52% after 4.5 hrs and this percentage of germ tube forming cells gradually decreases from 7.5 to 10.5 hr ( Table 1).…”

“…On the other hand, results suggested moderate filamentation about 44% in RPMI-1640 medium after 4.5 hr of inoculation of culture. However, influence of amino acids and vitamins for initiation of germ tube formation has been also reported in previous papers [45,49,51]. In another paper [39] it was also reported that C. albicans isolated from genitourinary tract show detectable filamentation in RPMI-1640 medium.…”

“…RPMI-1640 medium containing high level of glucose (0.45%), high phosphate (6 g/L), amino acids and biotin reduces the ability of C. albicans that was isolated from oral cavity to form germ tube [39]. As C. albicans activate hyphal development in response to glucose, phosphate, amino acids and biotin starvation [44,49,50]. On the other hand, results suggested moderate filamentation about 44% in RPMI-1640 medium after 4.5 hr of inoculation of culture.…”