Background: Pseudogymnoascus destructans , a psychrophile, causes bat white-nose syndrome (WNS). Pseudogymnoascus pannorum , a closely related fungus, causes human and canine diseases rarely. Both pathogens were reported from the same mines and caves in the United States, but only P. destructans caused WNS. Earlier genome comparisons revealed that P. pannorum contained more deduced proteins with ascribed enzymatic functions than P. destructans . Methods: We performed metabolic profiling with Biolog PM microarray plates to confirm in silico gene predictions. Results: P. pannorum utilized 78 of 190 carbon sources (41%), and 41 of 91 nitrogen compounds (43%) tested. P. destructans used 23 carbon compounds (12%) and 23 nitrogen compounds (24%). P. destructans exhibited more robust growth on the phosphorous compounds and nutrient supplements (83% and 15%, respectively) compared to P. pannorum (27% and 1%, respectively.). P. pannorum exhibited higher tolerance to osmolytes, pH extremes, and a variety of chemical compounds than P. destructans . Conclusions: An abundance of carbohydrate degradation pathways combined with robust stress tolerance provided clues for the soil distribution of P. pannorum . The limited metabolic profile of P. destructans was compatible with in silico predictions of far fewer proteins and enzymes. P. destructans ability to catabolize diverse phosphorous and nutrient supplements might be critical in the colonization and invasion of bat tissues. The present study of 1,047 different metabolic activities provides a framework for future gene-function investigations of the unique biology of the psychrophilic fungi.
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Galleria mellonella experimental model for bat fungal pathogen Pseudogymnoascus destructans and human fungal pathogen Pseudogymnoascus pannorum
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Abstract While vertebrate immune systems are appreciated for their complexity and adaptability, invertebrate immunity is often considered to be less complex. However, immune responses in many invertebrates likely involve sophisticated processes. Interactions between the crustacean host
Daphnia dentifera and its fungal pathogenMetschnikowia bicuspidata provide an excellent model for exploring the mechanisms underlying crustacean immunity. To explore the genomic basis of immunity inDaphnia , we used RNA‐sequencing technology to quantify differential gene expression between individuals of a single host genotype exposed or unexposed toM. bicuspidata over 24 h. Transcriptomic analyses showed that the number of differentially expressed genes between the control (unexposed) and experimental (exposed) groups increased over time. Gene ontology enrichment analysis revealed that differentially expressed genes were enriched for immune‐related molecules and processes, such as cuticle development, prostaglandin, and defense response processes. Our findings provide a suite of immunologically relevant genes and suggest the presence of a rapidly upregulated immune response involving the cuticle inDaphnia . Studies involving gene expression responses to pathogen exposure shine a light on the processes occurring during the course of infection. By leveraging knowledge on the genetic basis for immunity, immune mechanisms can be more thoroughly understood to refine our understanding of disease spread within invertebrate populations. -
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Abstract Lethal and sublethal effects of pathogens should theoretically select for host avoidance of these pathogenic organisms. Some amphibians can learn to avoid the pathogenic fungus
Batrachochytrium dendrobatidis (Bd) after one infection‐clearance event.Here, we investigated whether four taxonomically distinct amphibians, Cuban tree frogs
Osteopilus septentrionalis , southern toadsAnaxyrus (Bufo )terrestris , greenhouse frogsEleutherodactylus planirostris and pine woods tree frogsHyla femoralis , exhibited any innate or learned avoidance of Bd on a moist substrate and, if so, what cues they used to identify the fungus.Cuban tree frogs, pine woods tree frogs and greenhouse frogs did not appear to exhibit detectable innate or learned avoidance of Bd. However, southern toads learned to avoid Bd after only one exposure. Southern toads avoided any treatment containing Bd metabolites but did not avoid treatments that lacked Bd metabolites even when dead zoospores were present.
Bd metabolites appeared to be the cues that amphibians use to avoid Bd. These metabolites may have a distinct smell or may cause discomfort, which would be consistent with a classical or Pavlovian conditioning response.
Synthesis and applications . Not all species of amphibians respond the same way to Bd exposure; some can learn to avoid Bd and the metabolites it produces, while others do not. These findings have important implications for both management practices and policy, and should be considered when developing disease models and conservation plans for amphibians.
