Bacterial-fungal crosstalk is defined by a fungal lactone mycotoxin and its degradation by a bacterial lactonase.

Unlabelled: Bacteria, fungi, and mammals contain lactonases that can degrade the Gram-negative bacterial quorum sensing (QS) molecules N-acyl homoserine lactones (AHLs). AHLs are critical for bacteria to coordinate gene expression and pathogenicity with population density. However, AHL-degrading lactonases present variable substrate ranges, including degradation of the lactone mycotoxin patulin.

A single laccase acts as a key component of environmental sensing in a broad host range fungal pathogen.

Secreted laccases are important enzymes on a broad ecological scale for their role in mediating plant-microbe interactions, but within ascomycete fungi these enzymes have been primarily associated with melanin biosynthesis. In this study, a putatively secreted laccase, Sslac2, was characterized from the broad-host-range plant pathogen Sclerotinia sclerotiorum, which is largely unpigmented and is not dependent on melanogenesis for plant infection. Gene knockouts of Sslac2 demonstrate wide ranging developmental phenotypes and are functionally non-pathogenic.

Biogenesis, germination, and pathogenesis of spores.

SUMMARYSpores are primary infectious propagules for the majority of human fungal pathogens; however, relatively little is known about their fundamental biology. One strategy to address this deficiency has been to develop the basidiospores of into a model for pathogenic spore biology. Here, we provide an update on the state of the field with a comprehensive review of the data generated from the study of basidiospores from their formation (sporulation) and differentiation (germination) to their roles in pathogenesis.

Zebrafish cardiac repolarization does not functionally depend on the expression of the hERG1b-like transcript.

Zebrafish provide a translational model of human cardiac function. Their similar cardiac electrophysiology enables screening of human cardiac repolarization disorders, drug arrhythmogenicity, and novel antiarrhythmic therapeutics. However, while zebrafish cardiac repolarization is driven by delayed rectifier potassium channel current (I), the relative role of alternate channel transcripts is uncertain.

Invasive Californian death caps develop mushrooms unisexually and bisexually.

Canonical sexual reproduction among basidiomycete fungi involves the fusion of two haploid individuals of different mating types, resulting in a heterokaryotic mycelial body made up of genetically different nuclei. Using population genomics data and experiments, we discover mushrooms of the invasive and deadly Amanita phalloides can also be homokaryotic; evidence of sexual reproduction by single, unmated individuals. In California, genotypes of homokaryotic mushrooms are also found in heterokaryotic mushrooms, implying nuclei of homokaryotic mycelia are also involved in outcrossing.

Invasive Californian death caps develop mushrooms unisexually and bisexually.

Canonical sexual reproduction among basidiomycete fungi involves the fusion of two haploid individuals of different sexes, resulting in a heterokaryotic mycelial body made up of genetically different nuclei . Using population genomics data, we discovered mushrooms of the deadly invasive are also homokaryotic, evidence of sexual reproduction by single individuals. In California, genotypes of homokaryotic mushrooms are also found in heterokaryotic mushrooms, implying nuclei of homokaryotic mycelia also promote outcrossing.

The Hydrophobin Gene Family Confers a Fitness Trade-off between Spore Dispersal and Host Colonization in Penicillium expansum.

Hydrophobins are small amphipathic surface proteins found exclusively in fungi. In filamentous ascomycetes, one conserved role of a subset of hydrophobins is their requirement for spore dispersal. Other contributions of these proteins to fungal biology are less clear and vary across genera.

Inadvertent Selection of a Pathogenic Fungus Highlights Areas of Concern in Human Clinical Practices.

In studying the development of tolerance to common hospital cleaners (Oxivir and CaviCide™) in clinical isolate stocks of the emerging, multidrug-resistant yeast pathogen , we selected for a cleaner-tolerant subpopulation of a more common nosocomial pathogen, . Through the purification of each species and subsequent competition and other analyses, we determined that is capable of readily dominating mixed populations of and when exposed to hospital cleaners. This result suggests that exposure to antimicrobial compounds can preferentially select for low-level, stress-tolerant fungal pathogens.

Methods for Manipulating Spores.

Spores are essential for the long-term survival of many diverse organisms, due to their roles in reproduction and stress resistance. In the environmental human fungal pathogen, , basidiospores are robust cells with the ability to cause disease in animal models of infection. Here we describe methods for producing and purifying basidiospores in quantities sufficient for large-scale analyses.

Discovery of Fungus-Specific Targets and Inhibitors Using Chemical Phenotyping of Pathogenic Spore Germination.

There is a critical need for new antifungal drugs; however, the lack of available fungus-specific targets is a major hurdle in the development of antifungal therapeutics. Spore germination is a differentiation process absent in humans that could harbor uncharacterized fungus-specific targets. To capitalize on this possibility, we developed novel phenotypic assays to identify and characterize inhibitors of spore germination of the human fungal pathogen Cryptococcus.

Investigating the utility of adult zebrafish ex vivo whole hearts to pharmacologically screen hERG channel activator compounds.

There is significant interest in the potential utility of small-molecule activator compounds to mitigate cardiac arrhythmia caused by loss of function of hERG1a voltage-gated potassium channels. Zebrafish () have been proposed as a cost-effective, high-throughput drug-screening model to identify compounds that cause hERG1a dysfunction. However, there are no reports on the effects of hERG1a activator compounds in zebrafish and consequently on the utility of the model to screen for potential gain-of-function therapeutics.

Spore Germination as a Target for Antifungal Therapeutics.

Spores are required for long-term survival of many organisms, including most fungi. For the majority of fatal human fungal pathogens, spore germination is the key process required to initiate vegetative growth and ultimately cause disease. Because germination is required for pathogenesis, the process could hold fungal-specific targets for new antifungal drug development.

Infectious particle identity determines dissemination and disease outcome for the inhaled human fungal pathogen Cryptococcus.

The majority of invasive human fungal pathogens gain access to their human hosts via the inhalation of spores from the environment into the lung, but relatively little is known about this infectious process. Among human fungal pathogens the most frequent cause of inhaled fatal fungal disease is Cryptococcus, which can disseminate from the lungs to other tissues, including the brain, where it causes meningoencephalitis. To determine the mechanisms by which distinct infectious particles of Cryptococcus cause disseminated disease, we evaluated two developmental cell types (spores and yeast) in mouse models of infection.

Peptide-Like Nylon-3 Polymers with Activity against Phylogenetically Diverse, Intrinsically Drug-Resistant Pathogenic Fungi.

Understanding the dimensions of fungal diversity has major implications for the control of diseases in humans, plants, and animals and in the overall health of ecosystems on the planet. One ancient evolutionary strategy organisms use to manage interactions with microbes, including fungi, is to produce host defense peptides (HDPs). HDPs and their synthetic analogs have been subjects of interest as potential therapeutic agents.

Inhaled Cryptococcus neoformans elicits allergic airway inflammation independent of Nuclear Factor Kappa B signalling in lung epithelial cells.

Pulmonary challenge with the ubiquitous fungus Cryptococcus neoformans results in allergic airway inflammation (AAI) characterized by robust recruitment of eosinophils and T cells producing type 2 cytokines to the lungs. Previous studies have demonstrated a critical role for Nuclear Factor Kappa B (NF-κB) activation within lung epithelial cells (LECs) in driving AAI in response to protein allergens, yet the role of LEC-intrinsic NF-κB in promoting AAI following exposure to C. neoformans is poorly understood.

A Cationic Polymer That Shows High Antifungal Activity against Diverse Human Pathogens.

Invasive fungal diseases are generally difficult to treat and often fatal. The therapeutic agents available to treat fungi are limited, and there is a critical need for new agents to combat these deadly infections. Antifungal compound development has been hindered by the challenge of creating agents that are highly active against fungal pathogens but not toxic to the host.

Sporulation: how to survive on planet Earth (and beyond).

Sporulation is a strategy widely utilized by a wide variety of organisms to adapt to changes in their individual environmental niches and survive in time and/or space until they encounter conditions acceptable for vegetative growth. The spores produced by bacteria have been the subjects of extensive studies, and several systems such as Bacillus subtilis have provided ample opportunities to understand the molecular basis of spore biogenesis and germination. In contrast, the spores of other microbes, such as fungi, are relatively poorly understood.

Characterization of C-type lectins reveals an unexpectedly limited interaction between Cryptococcus neoformans spores and Dectin-1.

Phagocytosis by innate immune cells is an important process for protection against multiple pathologies and is particularly important for resistance to infection. However, phagocytosis has also been implicated in the progression of some diseases, including the dissemination of the human fungal pathogen, Cryptococcus neoformans. Previously, we identified Dectin-1 as a likely phagocytic receptor for C.

Stabilization of the Activated hERG Channel Voltage Sensor by Depolarization Involves the S4-S5 Linker.

Slow deactivation of hERG channels is critical for preventing cardiac arrhythmia yet the mechanistic basis for the slow gating transition is unclear. Here, we characterized the temporal sequence of events leading to voltage sensor stabilization upon membrane depolarization. Progressive increase in step depolarization duration slowed voltage-sensor return in a biphasic manner (τ 34 ms, τ = 2.

A Zebrafish Model of Cryptococcal Infection Reveals Roles for Macrophages, Endothelial Cells, and Neutrophils in the Establishment and Control of Sustained Fungemia.

Cryptococcal meningoencephalitis is a fungal infection that predominantly affects immunocompromised patients and is uniformly fatal if left untreated. Timely diagnosis is difficult, and screening or prophylactic measures have generally not been successful. Thus, we need a better understanding of early, asymptomatic pathogenesis.

Transcriptional control of sexual development in Cryptococcus neoformans.

Developmental processes are essential for the normal life cycles of many pathogenic fungi, and they can facilitate survival in challenging environments, including the human host. Sexual development of the human fungal pathogen Cryptococcus neoformans not only produces infectious particles (spores) but has also enabled the evolution of new disease-related traits such as drug resistance. Transcription factor networks are essential to the development and pathogenesis of C.

Leveraging a high resolution microfluidic assay reveals insights into pathogenic fungal spore germination.

Germination of spores into actively growing cells is a process essential for survival and pathogenesis of many microbes. Molecular mechanisms governing germination, however, are poorly understood in part because few tools exist for evaluating and interrogating the process. Here, we introduce an assay that leverages developments in microfluidic technology and image processing to quantitatively measure germination with unprecedented resolution, assessing both individual cells and the population as a whole.

Protein Composition of Infectious Spores Reveals Novel Sexual Development and Germination Factors in Cryptococcus.

Spores are an essential cell type required for long-term survival across diverse organisms in the tree of life and are a hallmark of fungal reproduction, persistence, and dispersal. Among human fungal pathogens, spores are presumed infectious particles, but relatively little is known about this robust cell type. Here we used the meningitis-causing fungus Cryptococcus neoformans to determine the roles of spore-resident proteins in spore biology.