Heterothermy and antifungal responses in bats

Hibernation, a period where bats have suppressed immunity and low body temperatures, provides the psychrophilic fungus Pseudogymnoascus destructans the opportunity to colonise bat skin, leading to severe disease in susceptible species. Innate immunity, which requires less energy and may remain more active during torpor, can control infections with local inflammation in some bat species that are resistant to infection. If infection is not controlled before emergence from hibernation, ineffective adaptive immune mechanisms are activated, including incomplete Th1, ineffective Th2, and variable Th17 responses. The Th17 and neutrophil responses, normally beneficial antifungal mechanisms, appear to be sources of immunopathology for susceptible bat species, because they are hyperactivated after return to homeothermy. Non-susceptible species show both well-balanced and suppressed immune responses both during and after hibernation.Peer reviewe

REVIEW OF THE CURRENT STATUS AND FUTURE PERSPECTIVES ON PSEUDOGYMNOASCUS DESTRUCTANS STUDIES WITH REFERENCE TO SPECIES FINDINGS IN BULGARIA

Emerging infectious diseases are a well-known threat to the wildlife and require complex research. There is a rapidly accumulating knowledge on the infectious disease of bats, named firstly White Nose Syndrome (WNS) and afterwards – White Nose Disease (WND), and its causative agent – the pathogenic fungus Pseudogymnoascus destructans. Although mass mortality of bats, known since a decade, is currently restricted to North America, the pathogen is of global concern as a potential threat to other hibernating bat populations. Therefore five years after the first comprehensive synthesis on the fungal ecology and relevant knowledge gaps (FOLEY ET AL. 2011), we decided to summarize the published information on the pathogen morphology, reproduction, ecological requirements, geographic distribution and systematic position. In addition, the present review compiles the available data on the affected bat species, mechanisms of WND, on the host response and on the effective treatment strategies with possible methods for fighting the pathogen to reduce the mortality in affected regions as well. Special attention is paid to the finding of the fungus in Bulgarian caves

Fukushima zum Trotz : Lateinamerika hält an seinen Nuklearprogrammen fest

Aim: A common pattern in biogeography is the scale-dependent effect of environmental variables on the spatial distribution of species. We tested the role of climatic and land cover variables in structuring the distribution of genetic variation in the grey long-eared bat, Plecotus austriacus, across spatial scales. Although landscape genetics has been widely used to describe spatial patterns of gene flow in a variety of taxa, volant animals have generally been neglected because of their perceived high dispersal potential.Location: England and Europe.Methods: We used a multiscale integrated approach, combining population genetics with species distribution modelling and geographical information under a causal modelling framework, to identify landscape barriers to gene flow and their effect on population structure and conservation status. Genotyping involved 23 polymorphic microsatellites and 259 samples from across the species' range.Results: We identified distinct population structure shaped by geographical barriers and evidence of population fragmentation at the northern edge of the range. Habitat suitability (as captured by species distribution models, SDMs) was the most important landscape variable affecting genetic connectivity at the broad spatial scale, while at the fine scale, lowland unimproved grasslands, the main foraging habitat of P. austriacus, played a pivotal role in promoting genetic connectivity.Main conclusions: The importance of lowland unimproved grasslands in determining the biogeography and genetic connectivity in P. austriacus highlights the importance of their conservation as part of a wider landscape management for fragmented edge populations. This study illustrates the value of using SDMs in landscape genetics and highlights the need for multiscale approaches when studying genetic connectivity in volant animals or taxa with similar dispersal abilities

Heterothermy and antifungal responses in bats

Hibernation, a period where bats have suppressed immunity and low body temperatures, provides the psychrophilic fungus Pseudogymnoascus destructans the opportunity to colonise bat skin, leading to severe disease in susceptible species. Innate immunity, which requires less energy and may remain more active during torpor, can control infections with local inflammation in some bat species that are resistant to infection. If infection is not controlled before emergence from hibernation, ineffective adaptive immune mechanisms are activated, including incomplete Th1, ineffective Th2, and variable Th17 responses. The Th17 and neutrophil responses, normally beneficial antifungal mechanisms, appear to be sources of immunopathology for susceptible bat species, because they are hyperactivated after return to homeothermy. Non-susceptible species show both well-balanced and suppressed immune responses both during and after hibernation

Considering adaptive genetic variation in climate change vulnerability assessment reduces species range loss projections

Local adaptations can determine the potential of populations to respond to environmental changes, yet adaptive genetic variation is commonly ignored in models forecasting species vulnerability and biogeographical shifts under future climate change. Here we integrate genomic and ecological modeling approaches to identify genetic adaptations associated with climate in two cryptic forest bats. We then incorporate this information directly into forecasts of range changes under future climate change and assessment of population persistence through the spread of climate-adaptive genetic variation (evolutionary rescue potential). Considering climate-adaptive potential reduced range loss projections, suggesting that failure to account for intraspecific variability can result in overestimation of future losses. On the other hand, range overlap between species was projected to increase, indicating that interspecific competition is likely to play an important role in limiting species’ future ranges. We show that although evolutionary rescue is possible, it depends on a population’s adaptive capacity and connectivity. Hence, we stress the importance of incorporating genomic data and landscape connectivity in climate change vulnerability assessments and conservation management

White-Nose Syndrome Fungus (Geomyces destructans) in Bat, France

White-nose syndrome is caused by the fungus Geomyces destructans and is responsible for the deaths of >1,000,000 bats since 2006. This disease and fungus had been restricted to the northeastern United States. We detected this fungus in a bat in France and assessed the implications of this finding

Pan-European Distribution of White-Nose Syndrome Fungus (Geomyces destructans) Not Associated with Mass Mortality

BACKGROUND: The dramatic mass mortalities amongst hibernating bats in Northeastern America caused by "white nose-syndrome" (WNS) continue to threaten populations of different bat species. The cold-loving fungus, Geomyces destructans, is the most likely causative agent leading to extensive destruction of the skin, particularly the wing membranes. Recent investigations in Europe confirmed the presence of the fungus G. destructans without associated mass mortality in hibernating bats in six countries but its distribution remains poorly known. METHODOLOGY/PRINCIPAL FINDINGS: We collected data on the presence of bats with white fungal growth in 12 countries in Europe between 2003 and 2010 and conducted morphological and genetic analysis to confirm the identity of the fungus as Geomyces destructans. Our results demonstrate the presence of the fungus in eight countries spanning over 2000 km from West to East and provide compelling photographic evidence for its presence in another four countries including Romania, and Turkey. Furthermore, matching prevalence data of a hibernaculum monitored over two consecutive years with data from across Europe show that the temporal occurrence of the fungus, which first becomes visible around February, peaks in March but can still be seen in some torpid bats in May or June, is strikingly similar throughout Europe. Finally, we isolated and cultured G. destructans from a cave wall adjacent to a bat with fungal growth. CONCLUSIONS/SIGNIFICANCE: G. destructans is widely found over large areas of the European continent without associated mass mortalities in bats, suggesting that the fungus is native to Europe. The characterisation of the temporal variation in G. destructans growth on bats provides reference data for studying the spatio-temporal dynamic of the fungus. Finally, the presence of G. destructans spores on cave walls suggests that hibernacula could act as passive vectors and/or reservoirs for G. destructans and therefore, might play an important role in the transmission process

Bat pluripotent stem cells reveal unique entanglement between host and viruses

Bats have evolved features unique amongst mammals, including flight, laryngeal echolocation, and certain species have been shown to have a unique immune response that may enable them to tolerate viruses such as SARS-CoVs, MERS-CoVs, Nipah, and Marburg viruses. Robust cellular models have yet to be developed for bats, hindering our ability to further understand their special biology and handling of viral pathogens. To establish bats as new model study species, we generated induced pluripotent stem cells (iPSCs) from a wild greater horseshoe bat (Rhinolophus ferrumequinum) using a modified Yamanaka protocol. Rhinolophids are amongst the longest living bat species and are asymptomatic carriers of coronaviruses, including one of the viruses most closely related to SARS-CoV-2. Bat induced pluripotent stem (BiPS) cells were stable in culture, readily differentiated into all three germ layers, and formed complex embryoid bodies, including organoids. The BiPS cells were found to have a core pluripotency gene expression program similar to that of other species, but it also resembled that of cells attacked by viruses. The BiPS cells produced a rich set of diverse endogenized viral sequences and in particular retroviruses. We further validated our protocol by developing iPS cells from an evolutionary distant bat species Myotis myotis (greater mouse-eared bat) non-lethally sampled in the wild, which exhibited similar attributes to the greater horseshoe bat iPS cells, suggesting that this unique pluripotent state evolved in the ancestral bat lineage. Although previous studies have suggested that bats have developed powerful strategies to tame their inflammatory response, our results argue that they have also evolved mechanisms to accommodate a substantial load of endogenous viral sequences and suggest that the natural history of bats and viruses is more profoundly intertwined than previously thought. Further study of bat iPS cells and their differentiated progeny should advance our understanding of the role bats play as virus hosts, provide a novel method of disease surveillance, and enable the functional studies required to ascertain the molecular basis of bats’ unique traits.N