title: Candida albicans forms a specialized "sexual" as well as "pathogenic" biofilm.
abstract: Candida albicans forms two types of biofilm in RPMI 1640 medium, depending upon the configuration of the mating type locus. In the prevalent a/α configuration, cells form a biofilm that is impermeable, impenetrable by leukocytes, and fluconazole resistant. It is regulated by the Ras1/cyclic AMP (cAMP) pathway. In the a/a or α/α configuration, white cells form a biofilm that is architecturally similar to an a/α biofilm but, in contrast, is permeable, penetrable, and fluconazole susceptible. It is regulated by the mitogen-activated protein (MAP) kinase pathway. The MTL-homozygous biofilm has been shown to facilitate chemotropism, a step in the mating process. This has led to the hypothesis that specialized MTL-homozygous biofilms facilitate mating. If true, then MTL-homozygous biofilms should have an advantage over MTL-heterozygous biofilms in supporting mating. We have tested this prediction using a complementation strategy and show that minority opaque a/a and α/α cells seeded in MTL-homozygous biofilms mate at frequencies 1 to 2 orders of magnitude higher than in MTL-heterozygous biofilms. No difference in mating frequencies was observed between seeded patches of MTL-heterozygous and MTL-homozygous cells grown on agar at 28°C in air or 20% CO2 and at 37°C. Mating frequencies are negligible in seeded patches of both a/α and a/a cells, in contrast to seeded biofilms. Together, these results support the hypothesis that MTL-homozygous (a/a or α/α) white cells form a specialized "sexual biofilm."
authors.affiliation: Developmental Studies Hybridoma Bank, Department of Biology, University of Iowa, Iowa City, Iowa, USA.
authors.forename: Yang-Nim
authors.initials: YN
authors.lastname: Park
authors.forename: Karla J
authors.initials: KJ
authors.lastname: Daniels
authors.forename: Claude
authors.initials: C
authors.lastname: Pujol
authors.forename: Thyagarajan
authors.initials: T
authors.lastname: Srikantha
authors.forename: David R
authors.initials: DR
authors.lastname: Soll
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D002176:Candida albicans / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D002634:Chemotaxis, Leukocyte; D000242:Cyclic AMP / Q000378:metabolism; D015725:Fluconazole / Q000494:pharmacology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D049770:Genes, Mating Type, Fungal / Q000235:genetics*; D018922:HL-60 Cells; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D010539:Permeability; D010641:Phenotype
chemical_list: D005656:Fungal Proteins; D015725:Fluconazole; D000242:Cyclic AMP