CANDIDA ALBICANS: BIOLOGY, GENETICS, AND PATHOGENICITY

Proline-induced Germ-tube Formation in Candida albicans: Role of Proline Uptake and Nitrogen Metabolism

“…No germ-tubes were observed when either D-proline or L-proline immobilized onto agarose (Sigma) was used as inducer. The time course of germ-tube induction by proline was similar to that observed with GlcNAc (Shepherd et al, 1985). The first protuberances were observed 60-90 min after exposure to the proline at 37 "C. After 150 min germ-tubes three to five times the length of the mother cell had appeared in more than 90% of the yeast cells.…”

“…The nitrogen source was 10 ~M-(NH,),SO, unless otherwise stated. To prepare cells for optimal germ-tube formation, cultures were starved by aeration in distilled water (Shepherd et al, 1980); germ-tube formation was induced by incubation at 37°C in 1 0 m~-imidazole buffer at a cell concentration of 1.5-2.0 x lo7 cells ml-* with either 2.5 mM-GlcNAc (Shepherd et al, 1980) or I0 mM-proline (Dabrowa & Howard, 1981). Germ-tube formation was assessed by phase-contrast microscopy after dispersal of cell aggregates by mild sonication (10-15 s) in 0.1 M-NaOH containing 1% (w/v) SDS.…”

“…The individual components of this medium were tested in various combinations for their ability to induce germ-tube formation in C. albicans strains A T C C 10261 and A72 (Table 1). Strain A T C C 10261 will not consistently form germ-tubes after growth in GSB unless it has been starved by aeration in distilled water (Shepherd et al, 1980). In contrast, yeast cells of strain A72 could be used immediately after harvest from GSB and it is referred to as a high responder strain (Mattia et al, 1982).…”

“…It has been previously observed that in some strains of C. albicans, starvation is a necessary prerequisite for germ-tube formation (Shepherd et al, 1980), and exponentially growing cells of strain ATCC 10261 do not reproducibly form germ-tubes when transferred directly to 37 "C with an inducer. However, when cells harvested at mid-exponential phase were first incubated in glucose-free medium for at least 3 h, germ-tube formation was consistently induced in > 90% of the cells (Fig.…”

Strain Variation AmongCandidaSpecies: Application of Various Typing Methods to Study the Epidemiology and Pathogenesis of Candidiasis in Hospitalized Patients

“…13 In addition to the diagnostic problems noted above, problems exist in interpreting cultures obtained from a variety of other body sites due to the propensity for Candida spp, particularly C albicans, to colonize these sites without causing infection. 2,14,21,22 Studies by Sandford et al 22 document the fact that despite colonization by C albicans in the respiratory, genitourinary, and gastrointestinal tract of the majority of patients with hematologic malignancies or bone marrow transplantation, only a small percentage ever develop invasive disease due to this organism. In contrast, 58% to 100% of patients colonized by C tropicalis develop systemic infection and thus are at significantly greater risk of developing a systemic infection due to C tropicalis.…”