Genetic Block in the Cellular Division Mechanism of a Morphological Mutant of a Yeast

Nickerson, Walter J.; Chung, C.

doi:10.1002/j.1537-2197.1954.tb14313.x

Cited by 50 publications

(21 citation statements)

References 17 publications

(10 reference statements)

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“…In contrast to other strains, C. albicans 1001 gave rise to morphological mutants in which a permanent pseudomycelial appearance was associated with a rough colonial morphology. Our mutants seem to be different from the pseudomycelial variant described several years ago (Nickerson & Chung, 1954;Ward & Nickerson, 1957;Nickerson, 1963). This variant appeared spontaneously and its morphology was affected by the presence of a diffusible substance produced by cultures of the wild-type, which seemed to be cysteine.…”

Section: Discussioncontrasting

confidence: 53%

Genetic Analysis of Candida albicans Morphological Mutants

Pomés¹,

Gil²,

Nombela³

1985

Microbiology

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Section: Discussioncontrasting

confidence: 53%

Genetic Analysis of Candida albicans Morphological Mutants

Pomés¹,

Gil²,

Nombela³

1985

Microbiology

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“…Odds (26) cited 13 references that an inoculum size of Յ10 6 /ml favored filamentous growth. A diffusible filament-suppressing molecule was hypothesized based on the distinctive morphology of C. albicans on agar plates following parallel streaking (24) or multiple cross-streaking (25). For instance, Nickerson and Chung (25) noted the "suppression of filamentation in strain 582 (a wild-type dimorphic strain of C. albicans) along the length of the streak facing strain 806 and the appearance of filaments in 582 only at the free ends of lateral streaks," while with three parallel streaks filamentous cells only arose from the outer borders of the two outer streaks (24).…”

Section: Discussionmentioning

confidence: 99%

Quorum Sensing in the Dimorphic Fungus Candida albicans Is Mediated by Farnesol

Hornby

Jensen

Lisec

et al. 2001

Appl Environ Microbiol

872

807

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The inoculum size effect in the dimorphic fungus Candida albicans results from production of an extracellular quorum-sensing molecule (QSM). This molecule prevents mycelial development in both a growth morphology assay and a differentiation assay using three chemically distinct triggers for germ tube formation (GTF): L-proline, N-acetylglucosamine, and serum (either pig or fetal bovine). In all cases, the presence of QSM prevents the yeast-to-mycelium conversion, resulting in actively budding yeasts without influencing cellular growth rates. QSM exhibits general cross-reactivity within C. albicans in that supernatants from strain A72 are active on five other strains of C. albicans and vice versa. The QSM excreted by C. albicans is farnesol (C 15 H 26 O; molecular weight, 222.37). QSM is extracellular, and is produced continuously during growth and over a temperature range from 23 to 43°C, in amounts roughly proportional to the CFU/milliliter. Production is not dependent on the type of carbon source nor nitrogen source or on the chemical nature of the growth medium. Both commercial mixed isomer and (E,E)-farnesol exhibited QSM activity (the ability to prevent GTF) at a level sufficient to account for all the QSM activity present in C. albicans supernatants, i.e., 50% GTF at ca. 30 to 35 M. Nerolidol was ca. two times less active than farnesol. Neither geraniol (C 10 ), geranylgeraniol (C 20 ), nor farnesyl pyrophosphate had any QSM activity.The dimorphic fungus Candida albicans is one of the most important fungi in medicine (26). It is a member of the normal flora residing in the intestinal tract of humans and other animals and is thought to be acquired during passage through the birth canal (26). C. albicans is also the model system for studying the basic biology of dimorphic fungi. Because of its medical importance, molecular tools are available with C. albicans that are unavailable for other dimorphic fungi (3). One unresolved problem in fungal biology is the dependence of cell morphology on initial cell density. For fungi exhibiting yeast-mycelium dimorphism, this phenomenon has been termed the inoculum size effect (19). Under otherwise identical conditions, budding yeasts are produced following inoculation at Ն10 6 cells/ml, whereas germ tubes and mycelia are produced with inocula of Ͻ10 6 cells/ml. We believe the inoculum size effect is a general phenomenon for all dimorphic fungi. This effect has been especially well documented for C. albicans. Cell density is listed by Odds (26) as 1 of 11 general factors favoring the filamentous form.In this study we isolate and characterize the extracellular quorum-sensing molecule (QSM) which is responsible for the inoculum size effect in C. albicans. Quorum sensing is a wellknown phenomenon in prokaryotes, but it has as yet only been hinted at in eukaryotes (18). Furthermore, since quorum sensing uses extracellular signal molecules, it is poised to mediate interactions of the producing fungus with its chemical and physical environment as well as with other bacteria an...

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“…Phenotypic instability has recently become a topic of interest in the opportunistic pathogen Candida albicans. There were early reports of variation in the streak morphology of clinical strains of C. albicans (2,11), but the analysis of colony morphology variation within single clinical isolates of C. albicans has only recently been initiated. Slutsky et al (18) noticed that some strains spontaneously switch to a number of variant colony morphologies at a high frequency and that such variants switch back to the normal (smooth) colony phenotype (and certain other variant colony phenotypes) at a high frequency (up to .…”

mentioning

confidence: 99%