The Histoplasma capsulatum URA5 gene, which has recently been cloned and disrupted by allelic replacement, encodes orotidine-5'-monophosphate pyrophosphorylase. Inactivation of URA5 by either targeted or UV mutagenesis results in disruption of the pyrimidine biosynthetic pathway and uracil auxotrophy. We examined the effect of uracil auxotrophy due to a ura5 mutation on H. capsulatum virulence ...

Cryptococcus neoformans var. neoformans ura5 mutants were transformed with linearized or circular plasmids containing the C. neoformans orotidine monophosphate pyrophosphorylase gene. Following electroporation, randomly isolated transformants were analyzed for the mitotic and meiotic stability of uracil prototrophy. All stable transformants tested showed nonspecific ectopic integration. Uracil ...

Cryptococcus neoformans is an opportunistic human pathogen, which infects the central nervous system causing the fatal disease, meningitis. In order to understand the genetic background of this human pathogen, the basic molecular manipulation techniques of deletion, overexpression, and so on have been developed. URA5, a gene encoding orotate phosphoribosyltransferase, has frequently been used t...

Cryptococcus neoformans is a major pathogen of humans throughout the world. Using commercial monoclonal antibodies to capsular epitopes, strains of C. neoformans manifest five serotypes: A, B, C, D and AD. Previous studies demonstrated significant divergence among serotypes A, B, C and D, which are typically haploid. In contrast, most strains of serotype AD are diploid or aneuploid and result f...

Cosuppression is a silencing phenomenon triggered by the introduction of homologous DNA sequences into the genomes of organisms as diverse as plants, fungi, flies, and nematodes. Here we report sex-induced silencing (SIS), which is triggered by tandem integration of a transgene array in the human fungal pathogen Cryptococcus neoformans. A SXI2a-URA5 transgene array was found to be post-transcri...

The oil-producing fungus Mortierella alpina 1S-4 is an industrial strain. In order to prepare host strains for a transformation system for this fungus, six uracil auxotrophs were obtained by means of random mutation with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). When the activities of orotate phosphoribosyl transferase (OPRTase, EC 2.4.2.10) and orotidine-5'-phosphate decarboxylase (OMPdecas...

INTRODUCTION Cryptococcal meningitis (CM) may be caused by several species of Cryptococcus. CASE PRESENTATION We describe a fatal case of CM in a HIV-positive patient from Ivory Coast infected by Cryptococcus neoformans VNI and Cryptococcusdeuterogattii. Isolates were recovered from cerebrospinal fluid (CSF) prior to systemic antifungal treatment. Six isolates were studied (the entire culture...

Cryptococcus neoformans is a human fungal pathogen that undergoes a dimorphic transition from yeast to hyphae during a-α opposite-sex mating and α-α unisexual reproduction (same-sex mating). Infectious spores are generated during both processes. We previously identified a sex-induced silencing (SIS) pathway in the C. neoformans serotype A var. grubii lineage, in which tandem transgene arrays tr...

An improved method has been developed for RNA interference in Cryptococcus neoformans, using opposing promoters to facilitate cloning and RNA interference targeting URA5 to allow selection of cells in which silencing is most effective. These advances significantly reduce the variability of silencing and the effort required for interference plasmid construction.