Histopathology confirms white-nose syndrome in bats in Europe

White-nose syndrome, associated with the fungal skin infection geomycosis, caused regional population collapse in bats in North America. Our results, based on histopathology, show the presence of white-nose syndrome in Europe. Dermatohistopathology on two bats (Myotis myotis) found dead in March 2010 with geomycosis in the Czech Republic had characteristics resembling Geomyces destructans infection in bats confirmed with white-nose syndrome in US hibernacula. In addition, a live M. myotis, biopsied for histopathology during hibernation in April 2011, had typical fungal infection with cupping erosion and invasion of muzzle skin diagnostic for white-nose syndrome and conidiospores identical to G. destructans that were genetically confirmed as G. destructans.     

Risk of infection of white-nose syndrome in North American vespertilionid bats in Mexico

Emerging diseases in wildlife pose challenges for conservation due to their usually rapid spread and high cause of mortality. The transmission of these diseases is a complex ecological process that involves interactions between groups of individuals, particularly in gregarious species. White-nose syndrome, caused by the fungus Pseudogymnoascus destructans, is increasingly infecting species of vespertilionid North American bats causing, in some cases, high population mortality. In this study, we modeled ecological niches projected as potential distributions for three strains of P. destructans (Asian, European and North American) and a group of species of verpertilionid bats in North America. Our model showed that the ecological niches of North American and Asian fungi strains are projected to expand into new geographic areas, with statistical significance between the two strains. In addition, our model identified the presence of all three strains of fungi in areas where the fungus has previously been documented as well as new suitable climatic areas for the establishment of P. destructans in North America: large regions of the central USA and highlands of Mexico in the Peninsula of Baja California, the Sierra Madre Occidental and Oriental, and Transvolcanic Mexican Belt. Our models identified 10 species of vespertilionid bats distributed similarly to P. destructans. Bats had a high risk of infection with WSN and a strong likelihood of dispersing the fungus.     

Prevalence and phenology of white-nose syndrome fungus Pseudogymnoascus destructans in bats from Poland

Pseudogymnoascus destructans (Pd), a parasitic fungus (being responsible for a disease known as white-nose syndrome, WNS) that caused mass mortality of cave-dwelling, hibernating bats in North America, appears to be native of Europe, where it also occurs on wintering bats, but no similar outbreaks of WNS have been recorded. Herein, we provide the first account on prevalence and phenology of P. destructans in Poland. Bats were counted once per month, from October or January to May (2010-2013), in an abandoned ore mine in southern Poland. Presence of P. destructans in two samples was confirmed by sequencing of isolated fungal DNA. Observations of phenotypically identical mycosis on bats hibernating at this site in March 2006 are likely to be the first known records of P. destructans from Poland. All Pd-suspected individuals were Myotis myotis with an exception of one Myotis daubentonii. The first Pd-suspected bats were noted in mid-February, but their number was the highest in March, what overlapped with maximum numbers of hibernating M. myotis. The prevalence in March was 7%–27% of M. myotis individuals. No mass mortality of bats was observed in the mine, with only three dead individuals found in the hibernaculum which hosted up to 130 bats, representing 6–7 species.     

Skin fungal assemblages of bats vary based on susceptibility to white-nose syndrome

Microbial skin assemblages, including fungal communities, can influence host resistance to infectious diseases. The diversity-invasibility hypothesis predicts that high-diversity communities are less easily invaded than species-poor communities, and thus diverse microbial communities may prevent pathogens from colonizing a host. To explore the hypothesis that host fungal communities mediate resistance to infection by fungal pathogens, we investigated characteristics of bat skin fungal communities as they relate to susceptibility to the emerging disease white-nose syndrome (WNS). Using a culture-based approach, we compared skin fungal assemblage characteristics of 10 bat species that differ in susceptibility to WNS across 10 eastern U.S. states. The fungal assemblages on WNS-susceptible bat species had significantly lower alpha diversity and abundance compared to WNS-resistant species. Overall fungal assemblage structure did not vary based on WNS-susceptibility, but several yeast species were differentially abundant on WNS-resistant bat species. One yeast species inhibited Pseudogymnoascus destructans (Pd), the causative agent on WNS, in vitro under certain conditions, suggesting a possible role in host protection. Further exploration of interactions between Pd and constituents of skin fungal assemblages may prove useful for predicting susceptibility of bat populations to WNS and for developing effective mitigation strategies.Subject terms: Microbiome, Fungal ecology     

Pathophysiology of white-nose syndrome in bats: a mechanistic model linking wing damage to mortality

White-nose syndrome is devastating North American bat populations but we lack basic information on disease mechanisms. Altered blood physiology owing to epidermal invasion by the fungal pathogen Geomyces destructans (Gd) has been hypothesized as a cause of disrupted torpor patterns of affected hibernating bats, leading to mortality. Here, we present data on blood electrolyte concentration, haematology and acid–base balance of hibernating little brown bats, Myotis lucifugus, following experimental inoculation with Gd. Compared with controls, infected bats showed electrolyte depletion (i.e. lower plasma sodium), changes in haematology (i.e. increased haematocrit and decreased glucose) and disrupted acid–base balance (i.e. lower CO₂ partial pressure and bicarbonate). These findings indicate hypotonic dehydration, hypovolaemia and metabolic acidosis. We propose a mechanistic model linking tissue damage to altered homeostasis and morbidity/mortality.     

Evaporative water loss is a plausible explanation for mortality of bats from white-nose syndrome

White-nose syndrome (WNS) has caused alarming declines of North American bat populations in the 5 years since its discovery. Affected bats appear to starve during hibernation, possibly because of disruption of normal cycles of torpor and arousal. The importance of hydration state and evaporative water loss (EWL) for influencing the duration of torpor bouts in hibernating mammals recently led to "the dehydration hypothesis," that cutaneous infection of the wing membranes of bats with the fungus Geomyces destructans causes dehydration which in turn, increases arousal frequency during hibernation. This hypothesis predicts that uninfected individuals of species most susceptible to WNS, like little brown bats (Myotis lucifugus), exhibit high rates of EWL compared to less susceptible species. We tested the feasibility of this prediction using data from the literature and new data quantifying EWL in Natterer's bats (Myotis nattereri), a species that is, like other European bats, sympatric with G. destructans but does not appear to suffer significant mortality from WNS. We found that little brown bats exhibited significantly higher rates of normothermic EWL than did other bat species for which comparable EWL data are available. We also found that Natterer's bats exhibited significantly lower rates of EWL, in both wet and dry air, compared with values predicted for little brown bats exposed to identical relative humidity (RH). We used a population model to show that the increase in EWL required to cause the pattern of mortality observed for WNS-affected little brown bats was small, equivalent to a solitary bat hibernating exposed to RH of ～95%, or clusters hibernating in ～87% RH, as opposed to typical near-saturation conditions. Both of these results suggest the dehydration hypothesis is plausible and worth pursuing as a possible explanation for mortality of bats from WNS.     

Frequent arousal from hibernation linked to severity of infection and mortality in bats with white-nose syndrome

White-nose syndrome (WNS), an emerging infectious disease that has killed over 5.5 million hibernating bats, is named for the causative agent, a white fungus (Geomyces destructans (Gd)) that invades the skin of torpid bats. During hibernation, arousals to warm (euthermic) body temperatures are normal but deplete fat stores. Temperature-sensitive dataloggers were attached to the backs of 504 free-ranging little brown bats (Myotis lucifugus) in hibernacula located throughout the northeastern USA. Dataloggers were retrieved at the end of the hibernation season and complete profiles of skin temperature data were available from 83 bats, which were categorized as: (1) unaffected, (2) WNS-affected but alive at time of datalogger removal, or (3) WNS-affected but found dead at time of datalogger removal. Histological confirmation of WNS severity (as indexed by degree of fungal infection) as well as confirmation of presence/absence of DNA from Gd by PCR was determined for 26 animals. We demonstrated that WNS-affected bats aroused to euthermic body temperatures more frequently than unaffected bats, likely contributing to subsequent mortality. Within the subset of WNS-affected bats that were found dead at the time of datalogger removal, the number of arousal bouts since datalogger attachment significantly predicted date of death. Additionally, the severity of cutaneous Gd infection correlated with the number of arousal episodes from torpor during hibernation. Thus, increased frequency of arousal from torpor likely contributes to WNS-associated mortality, but the question of how Gd infection induces increased arousals remains unanswered.     

Hormones and hibernation: possible links between hormone systems,winter energy balance and white-nose syndrome in bats

This article is part of a Special Issue “Energy Balance”.     

Recovery of little brown bats (Myotis lucifugus) from natural infection with Geomyces destructans, white-nose syndrome

Geomyces destructans produces the white fungal growth on the muzzle and the tacky white discoloration on wings and ears that characterize white-nose syndrome (WNS) in cave-hibernating bats. To test the hypothesis that postemergent WNS-infected bats recover from infection with G. destructans, 30 little brown bats (Myotis lucifugus) were collected in May 2009 from a WNS-affected hibernation site in New Jersey. All bats were confirmed to be infected with G. destructans using a noninvasive fungal tape method to identify the conidia of G. destructans and polymerase chain reaction (PCR). The bats were then held in captivity and given supportive care for 70 days. Of the 26 bats that survived and were humanely killed after 70 days, 25 showed significant improvement in the external appearance of wing membranes, had no microscopic evidence of infection by G. destructans, and had wing tissue samples that were negative for G. destructans by PCR. A subset of the bats was treated topically at the beginning of the rehabilitation study with a dilute vinegar solution, but treatment with vinegar provided no added advantage to recovery. Provision of supportive care to homeothermic bats was sufficient for full recovery from WNS. One bat at day 70 still had both gross pathology and microscopic evidence of WNS in wing membranes and was PCR-positive for G. destructans. Dense aggregates of neutrophils surrounded the hyphae that remained in the wing membrane of this bat.     

Changes in body condition of hibernating bats support the thrifty female hypothesis and predict consequences for populations with white-nose syndrome

White-nose syndrome (WNS) is a new disease of bats that has devastated populations in eastern North America. Infection with the fungus, Geomyces destructans, is thought to increase the time bats spend out of torpor during hibernation, leading to starvation. Little is known about hibernation in healthy, free-ranging bats and more data are needed to help predict consequences of WNS. Trade-offs presumably exist between the energetic benefits and physiological/ecological costs of torpor, leading to the prediction that the relative importance of spring energy reserves should affect an individual''s use of torpor and depletion of energy reserves during winter. Myotis lucifugus mate during fall and winter but females do not become pregnant until after spring emergence. Thus, female reproductive success depends on spring fat reserves while male reproductive success does not. Consequently, females should be “thrifty” in their use of fat compared to males. We measured body condition index (BCI; mass/forearm length) of 432 M. lucifugus in Manitoba, Canada during the winter of 2009/2010. Bats were captured during the fall mating period (n = 200), early hibernation (n = 125), and late hibernation (n = 128). Adult females entered hibernation with greater fat reserves and consumed those reserves more slowly than adult males and young of the year. Consequently, adult females may be more likely than males or young of the year to survive the disruption of energy balance associated with WNS, although surviving females may not have sufficient reserves to support reproduction.     

Nitric oxide in physiology and pathology

Summary Nitric oxide (NO) can exert a multitude of biological actions. NO, formed froml-arginine by a calcium-dependent enzyme (NO synthase) plays a key physiological role in regulating vascular tone and integrity. NO, formed by a constitutive neuronal isoform of NO synthase, likewise plays an important neuromodulator role. By contrast, high levels of NO can be generated following induction of a calcium-independent isoform of NO synthase. This excessive production of NO can provoke hypotension such as that observed in septic shock, and can exert cytotoxic actions leading to tissue injury and inflammation. Selective inhibitors of this inducible isoform thus have therapeutic potential in a number of disease states.     

Tissue physiology and pathology of aromatase

Aromatase is expressed in multiple tissues, indicating a crucial role for locally produced oestrogens in the differentiation, regulation and normal function of several organs and processes. This review is an overview of the role of aromatase in different tissues under normal physiological conditions and its contribution to the development of some oestrogen-related pathologies.     

Free radicals in physiology and pathology.

Free radicals are molecules with odd number of electrons and a high instability. Free radicals, which can occur in both organic (i.e., quinones) and inorganic molecules (i.e., O2-), are very reactive and their reactions are critical for the normal activity of a wide spectrum of biologic processes. They are also produced in the catalytic action of a variety of cellular enzymes and electron transport processes and are implicated in a number of physiologic and pathologic processes. Organisms can be exposed to free radicals in many ways other than through the processes of normal metabolism. Irradiation of organisms with electromagnetic radiation generates primary radicals (e-aq, OH., and H.), which can then undergo secondary reactions with dissolved O2 or with cellular solutes. In addition, a wide variety of environmental agents (drugs capable of redox cycling, and xenobiotics that can form free radical metabolites) including the aging process cause free radical damage to cells. This review deals with the reactions they can undergo and discusses the free radicals related to toxicology.     

Pulmonary neuroendocrine cells in physiology and pathology

Pulmonary neuroendocrine cells are scant and widespread within the pulmonary epithelium. The function they play is not fully known, more studies are needed to clearly define it. They have been implicated however, as either the culprit or victim of many pulmonary diseases. That is the reason, why so many scientists take interest in the pulmonary neuroendocrine system. This paper reviews current information regarding pulmonary neuroendocrine cells, their origin, morphology, ontogeny, role, neuroendocrine cell markers, dysplasia and hyperplasia of pulmonary neuroendocrine cells in various conditions, diffuse idiopathic pulmonary neuroendocrine cell hyperplasia, typical carcinoid, atypical carcinoid, small-cell lung carcinoma, large-cell neuroendocrine carcinoma and the unusual spectrum of pulmonary neuroendocrine tumours.