Biology subjects

Munoz, J. F.

Publications and source records attributed to Munoz, J. F..

4 recordsLinked to original sources

bioRxiv2018

Coordinated host-pathogen transcriptional dynamics revealed using sorted subpopulations and single, Candida albicans infected macrophages

The outcome of fungal infections depends on interactions with innate immune cells. Within a population of macrophages encountering C. albicans, there are distinct host-pathogen trajectories; however, little is known about the molecular heterogeneity that governs these fates. We developed an experimental system to separate interaction stages and single macrophage cells infected with C. albicans from uninfected cells and assessed transcriptional variability in the host and fungus. Macrophages displayed an initial up-regulation of pathways involved in phagocytosis and proinflammatory response after C. albicans exposure that declined during later time points. Phagocytosed C. albicans shifted expression programs to survive the nutrient poor phagosome and remodeled the cell wall. The transcriptomes of single infected macrophages and phagocytosed C. albicans revealed a tightly coordinated shift in gene expression co-stages and revealed expression bimodality and differential splicing that may drive infection outcome. This work establishes an approach for studying host-pathogen trajectories to resolve heterogeneity in dynamic populations.

genomics↗

bioRxiv2018

Pathways of pathogenicity: The transcriptional stages of germination in the fatal fungal pathogen Rhizopus delemar

Rhizopus delemar is an invasive fungal pathogen, responsible for the frequently fatal disease mucormycosis. Germination, a crucial mechanism by which spores of Rhizopus delemar infect and cause disease, is a key developmental process that transforms the dormant spore state into a vegetative one. Understanding the molecular mechanisms which underpin this transformation may be key to controlling mucormycosis, however the regulation of germination remains poorly understood. This study describes the phenotypic and transcriptional changes which take place over the course of germination. This process is characterised by four distinct stages: dormancy, isotropic swelling, germ tube emergence and hyphal growth. Dormant spores are shown to be transcriptionally unique, expressing a subset of transcripts absent in later developmental stages. A large shift in the expression profile is prompted by the initiation of germination, with genes involved in respiration, chitin, cytoskeleton and actin regulation appearing to be important for this transition. A period of transcriptional consistency can be seen throughout isotropic swelling, before the transcriptional landscape shifts again at the onset of hyphal growth. This study provides a greater understanding of the regulation of germination and highlights processes involved in transforming Rhizopus delemar from a single to a multicellular organism.\n\nImportanceGermination is key to the growth of many organisms, including fungal spores. Mucormycete spores exist abundantly within the environment and germinate to form hyphae. These spores are capable of infecting immunocompromised individuals, causing the disease mucormycosis Germination from spore to hyphae within patients leads to angioinvasion, tissue necrosis and often fatal infections. This study advances our understanding of how spore germination occurs in the mucormycetes, identifying processes we may be able to inhibit to help prevent or treat mucormycosis.

microbiology↗

bioRxiv2018

Genomic basis of multidrug-resistance, mating, and virulence in Candida auris and related emerging species

Candida auris is an emergent fungal pathogen of rising public health concern due to increasing reports of outbreaks in healthcare settings and resistance to multiple classes of antifungal drugs. While distantly related to the more common pathogens C. albicans and C. glabrata, C. auris is closely related to three rarely observed and often multidrug-resistant species, C. haemulonii, C. duobushaemulonii and C. pseudohaemulonii. Here, we generated and analyzed near complete genome assemblies and RNA-Seq-guided gene predictions for isolates from each of the four major C. auris clades and for C. haemulonii, C. duobushaemulonii and C. pseudohaemulonii. Our analyses mapped seven chromosomes and revealed chromosomal rearrangements between C. auris clades and related species. We found conservation of genes involved in mating and meiosis and identified both MTLa and MTL C. auris isolates, suggesting the potential for mating between clades. Gene conservation analysis highlighted that many genes linked to drug resistance and virulence in other pathogenic Candida species are conserved in C. auris and related species including expanded families of transporters and lipases, as well as mutations and copy number variants in ERG11 that confer drug resistance. In addition, we found genetic features of the emerging species that likely underlie differences in virulence and drug response between these and other Candida species, including genes involved in cell wall structure. To begin to characterize the species-specific genes important for antifungal response, we profiled the gene expression of C. auris in response to voriconazole and amphotericin B and found induction of several transporters and metabolic regulators that may play a role in drug resistance. This study provides a comprehensive view of the genomic basis of drug resistance, potential for mating, and virulence in this emerging fungal clade.

genomics↗

bioRxiv2017

Genome analysis reveals evolutionary mechanisms of adaptation in systemic dimorphic fungi

Dimorphic fungal pathogens cause a significant human disease burden and unlike most fungal pathogens affect immunocompetent hosts. To examine the origin of virulence of these fungal pathogens, we compared genomes of classic systemic, opportunistic, and non-pathogenic species, including Emmonsia and two basal branching, non-pathogenic species in the Ajellomycetaceae, Helicocarpus griseus and Polytolypa hystricis. We found that gene families related to plant degradation, secondary metabolites synthesis, and amino acid and lipid metabolism are retained in H. griseus and P. hystricis. While genes involved in the virulence of dimorphic pathogenic fungi are conserved in saprophytes, changes in the copy number of proteases, kinases and transcription factors in systemic dimorphic relative to non-dimorphic species may have aided the evolution of specialized gene regulatory programs to rapidly adapt to higher temperatures and new nutritional environments. Notably, both of the basal branching, non-pathogenic species appear homothallic, with both mating type locus idiomorphs fused at a single locus, whereas all related pathogenic species are heterothallic. These differences revealed that independent changes in nutrient acquisition capacity have occurred in the Onygenaceae and Ajellomycetaceae, and underlie how the dimorphic pathogens have adapted to the human host and decreased their capacity for growth in environmental niches.

genomics↗