BACKGROUND: Coevolution between pathogens and their hosts decreases host morbidity and mortality. Bats host and can tolerate viruses which can be lethal to other vertebrate orders, including humans. Bat adaptations to infection include localized immune response, early pathogen sensing, high interferon expression without pathogen stimulation, and regulated inflammatory response. The immune reaction is costly, and bats suppress high-cost metabolism during torpor. In the temperate zone, bats hibernate in winter, utilizing a specific behavioural adaptation to survive detrimental environmental conditions and lack of energy resources. Hibernation torpor involves major physiological changes that pose an additional challenge to bat-pathogen coexistence. Here, we compared bat cellular reaction to viral challenge under conditions simulating hibernation, evaluating the changes between torpor and euthermia. RESULTS: We infected the olfactory nerve-derived cell culture of Myotis myotis with an endemic bat pathogen, European bat lyssavirus 1 (EBLV-1). After infection, the bat cells were cultivated at two different temperatures, 37 °C and 5 °C, to examine the cell response during conditions simulating euthermia and torpor, respectively. The mRNA isolated from the cells was sequenced and analysed for differential gene expression attributable to the temperature and/or infection treatment. In conditions simulating euthermia, infected bat cells produce an excess signalling by multitude of pathways involved in apoptosis and immune regulation influencing proliferation of regulatory cell types which can, in synergy with other produced cytokines, contribute to viral tolerance. We found no up- or down-regulated genes expressed in infected cells cultivated at conditions simulating torpor compared to non-infected cells cultivated under the same conditions. When studying the reaction of uninfected cells to the temperature treatment, bat cells show an increased production of heat shock proteins (HSPs) with chaperone activity, improving the bat's ability to repair molecular structures damaged due to the stress related to the temperature change. CONCLUSIONS: The lack of bat cell reaction to infection in conditions simulating hibernation may contribute to the virus tolerance or persistence in bats. Together with the cell damage repair mechanisms induced in response to hibernation, the immune regulation may promote bats' ability to act as reservoirs of zoonotic viruses such as lyssaviruses.
- MeSH
- Chiroptera * physiology MeSH
- Hibernation * MeSH
- Lyssavirus * MeSH
- Transcriptome MeSH
- Viruses * MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Hibernating amphibians are suitable for the research on the adaptation of gut microbiota to long-term fasting and cold stresses. However, the previous studies mainly focus on the large or whole gut microbiota but not the small gut microbiota. To test the structural discrepancy between the small and large gut microbiota during hibernation, we performed two independent batches of 16S rRNA gene amplicon sequencing to profile the small and large gut microbiota of hibernating Asiatic toad (Bufo gargarizans) from two wild populations. Both batches of data revealed that Proteobacteria, Bacteroidetes, and Firmicutes were the three most dominant phyla in the small and large gut microbiota. Three core OTUs with 100% occurrence in all gut microbiotas were annotated as Pseudomonas. A significant structural discrepancy was detected between the small and large gut microbiota. For instance, Proteobacteria assembled in the small intestine with a higher proportion than it did in the large intestine, but Bacteroidetes and Firmicutes assembled in the large intestine with a higher proportion than they did in the small intestine. The large gut microbiota exhibited higher diversity than the small gut microbiota. Nevertheless, a severe batch effect existed in the structural analysis of the gut microbiotas. The large gut microbiota showed a better resistance to the batch effect than the small gut microbiota did. This study provides preliminary evidence that microbes assemble in the small and large intestines of amphibians with discrepant patterns during hibernation.
- MeSH
- Hibernation * MeSH
- RNA, Ribosomal, 16S genetics MeSH
- Bufonidae genetics microbiology MeSH
- Gastrointestinal Microbiome * MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
Cílem tohoto článku je zdůraznit respektování mechanismů odpovědi na inzult při volbě nutriční strategie v časné fázi kritického stavu. Současně článek pojednává o rizicích spojených s časnou agresivní nutriční intervencí, a to jak pro energetický, tak také pro proteinový příjem. Dnes se zdá, že nejoptimálnější volbou nutriční podpory v průběhu prvního týdne pobytu na jednotce intenzivní péče (JIP) je postupné navyšování dávky jak energie, tak i bílkovin. V číselném vyjádření to přibližně znamená vzestup dávky energie o 5 kcal/kg/den a vzestup dávky bílkovin o 0,2 g/kg/den. Platí to ovšem pouze u pacientů přicházejících na JIP s normální hodnotou body mass index, tedy bez malnutrice či obezity. Obě tyto kategorie vyžadují zvláštní pozornost přesahující rozsah tohoto článku.
The aim of this article is to emphasize the importance of taking into account the mechanism of host's response to insult when choosing a nutritional strategy in the early phase of a critical illness. At the same time, the article discusses the risks associated with early aggressive nutritional intervention for both energy and protein intake. Today, it seems that the most optimal choice of nutritional support during the first week of stay in the ICU is a gradual increase in both energy and protein intake. In numerical terms, this means a daily increase in energy dose of approximately 5 kcal/kg/day and a daily increase in protein dose of 0.2 g /kg/day. However, this only applies to patients admitted to the ICU with a normal body mass index, i.e. without malnutrition or without obesity. Both of these categories require special attention beyond the scope of this article.
- Keywords
- překrmování,
- MeSH
- Autophagy MeSH
- Hibernation MeSH
- Critical Illness MeSH
- Humans MeSH
- Nutritional Support * methods MeSH
- Nutrition Therapy MeSH
- Critical Care * MeSH
- Check Tag
- Humans MeSH
- Publication type
- Review MeSH
The greater mouse-eared bat (Myotis myotis) is a flagship species for the protection of hibernation and summer maternity roosts in the Western Palearctic region. A range of pathogenic agents is known to put pressure on populations, including the white-nose syndrome fungus, for which the species shows the highest prevalence and infection intensity of all European bat species. Here, we perform analysis of blood parameters characteristic for the species during its natural annual life cycle in order to establish reference values. Despite sexual dimorphism and some univariate differences, the overall multivariate pattern suggests low seasonal variation with homeostatic mechanisms effectively regulating haematology and blood biochemistry ranges. Overall, the species displayed a high haematocrit and haemoglobin content and high concentration of urea, while blood glucose levels in swarming and hibernating bats ranged from hypo- to normoglycaemic. Unlike blood pH, concentrations of electrolytes were wide ranging. To conclude, baseline data for blood physiology are a useful tool for providing suitable medical care in rescue centres, for studying population health in bats adapting to environmental change, and for understanding bat responses to stressors of conservation and/or zoonotic importance.
- MeSH
- Chiroptera blood physiology MeSH
- Hematocrit standards MeSH
- Hematologic Tests standards MeSH
- Hibernation MeSH
- Climate MeSH
- Reference Values MeSH
- Seasons MeSH
- Sentinel Species physiology MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Arctic Regions MeSH
Where microbes colonizing skin surface may help maintain organism homeostasis, those that invade living skin layers cause disease. In bats, white-nose syndrome is a fungal skin infection that affects animals during hibernation and may lead to mortality in severe cases. Here, we inferred the amount of fungus that had invaded skin tissue of diseased animals. We used simulations to estimate the unobserved disease severity in a non-lethal wing punch biopsy and to relate the simulated pathology to the measured fungal load in paired biopsies. We found that a single white-nose syndrome skin lesion packed with spores and hyphae of the causative agent, Pseudogymnoascus destructans, contains 48.93 pg of the pathogen DNA, which amounts to about 1560 P destructans genomes in one skin lesion. Relating the information to the known UV fluorescence in Nearctic and Palearctic bats shows that Nearctic bats carry about 1.7 µg of fungal DNA per cm2, whereas Palearctic bats have 0.04 µg cm-2 of P. destructans DNA. With the information on the fungal load that had invaded the host skin, the researchers can now calculate disease severity as a function of invasive fungal growth using non-destructive UV light transillumination of each bat's wing membranes. Our results will enable and promote thorough disease severity assessment in protected bat species without the need for extensive animal and laboratory labor sacrifices.
- MeSH
- Ascomycota * metabolism pathogenicity MeSH
- Chiroptera microbiology MeSH
- Dermatomycoses * microbiology prevention & control therapy veterinary MeSH
- Hibernation * MeSH
- Wings, Animal microbiology MeSH
- Skin microbiology MeSH
- Ultraviolet Rays * MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Resistance and tolerance allow organisms to cope with potentially life-threatening pathogens. Recently introduced pathogens initially induce resistance responses, but natural selection favors the development of tolerance, allowing for a commensal relationship to evolve. Mycosis by Pseudogymnoascus destructans, causing white-nose syndrome (WNS) in Nearctic hibernating bats, has resulted in population declines since 2006. The pathogen, which spread from Europe, has infected species of Palearctic Myotis for a longer period. We compared ecologically relevant responses to the fungal infection in the susceptible Nearctic M. lucifugus and less susceptible Palearctic M. myotis, to uncover factors contributing to survival differences in the two species. Samples were collected from euthermic bats during arousal from hibernation, a naturally occurring phenomenon, during which transcriptional responses are activated. We compared the whole-transcriptome responses in wild bats infected with P. destructans hibernating in their natural habitat. Our results show dramatically different local transcriptional responses to the pathogen between uninfected and infected samples from the two species. Whereas we found 1526 significantly upregulated or downregulated transcripts in infected M. lucifugus, only one transcript was downregulated in M. myotis. The upregulated response pathways in M. lucifugus include immune cell activation and migration, and inflammatory pathways, indicative of an unsuccessful attempt to resist the infection. In contrast, M. myotis appears to tolerate P. destructans infection by not activating a transcriptional response. These host-microbe interactions determine pathology, contributing to WNS susceptibility, or commensalism, promoting tolerance to fungal colonization during hibernation that favors survival.
Hibernating bats optimise the duration of torpor bouts and arousals in relation to hibernaculum microclimatic conditions and fat reserves. Clustering has significant physiological and ecological benefits, promoting successful hibernation of individuals. Such aggregations may help maintain optimal temperatures, allowing better energy utilisation than in solitarily bats. However, aroused bats in a cluster could conceivably disturb those still hibernating, starting an energy-demanding arousal process. Our study was conducted over two winters in two different hibernacula (cave and mine) in the Czech Republic, where Greater mouse-eared bats (Myotis myotis) have previously been diagnosed with white-nose syndrome. In 118 arousal episodes we recorded 193 individual arousals in which a warming phase was observed, 135 (69.9%) being cold arousals, where bats ceased increasing their body temperatures at ≤ 10 °C. The remaining arousals were standard normothermic arousals, where body (fur) surface temperatures reached > 20 °C. Cold arousals occurred during the mid- and late hibernation periods, suggesting they were a response to disturbance by a neighbour in the same cluster. Arousal cascades, where bats aroused in series, were rare (12.7%) and reached a maximum in mid-January. Our data suggest that Myotis bats prolong their torpor bouts using numerous cold arousals but few arousal cascades. Upon arrival of a bat, the clustered bats show tolerance to disturbing by conspecifics.
- MeSH
- Arousal MeSH
- Chiroptera physiology MeSH
- Behavior, Animal MeSH
- Hibernation * MeSH
- Cold Temperature MeSH
- Seasons MeSH
- Torpor MeSH
- Body Temperature MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
BACKGROUND: Spatiotemporal distribution patterns are important infectious disease epidemiological characteristics that improve our understanding of wild animal population health. The skin infection caused by the fungus Pseudogymnoascus destructans emerged as a panzootic disease in bats of the northern hemisphere. However, the infection status of bats over an extensive geographic area of the Russian Federation has remained understudied. RESULTS: We examined bats at the geographic limits of bat hibernation in the Palearctic temperate zone and found bats with white-nose syndrome (WNS) on the European slopes of the Ural Mountains through the Western Siberian Plain, Central Siberia and on to the Far East. We identified the diagnostic symptoms of WNS based on histopathology in the Northern Ural region at 11° (about 1200 km) higher latitude than the current northern limit in the Nearctic. While body surface temperature differed between regions, bats at all study sites hibernated in very cold conditions averaging 3.6 °C. Each region also differed in P. destructans fungal load and the number of UV fluorescent skin lesions indicating skin damage intensity. Myotis bombinus, M. gracilis and Murina hilgendorfi were newly confirmed with histopathological symptoms of WNS. Prevalence of UV-documented WNS ranged between 16 and 76% in species of relevant sample size. CONCLUSIONS: To conclude, the bat pathogen P. destructans is widely present in Russian hibernacula but infection remains at low intensity, despite the high exposure rate.
- MeSH
- Ascomycota * MeSH
- Chiroptera * classification genetics MeSH
- Dermatomycoses epidemiology veterinary MeSH
- Animals, Wild MeSH
- Species Specificity MeSH
- Hibernation MeSH
- Molecular Typing MeSH
- Nose * MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Russia epidemiology MeSH
In underground hibernacula temperate northern hemisphere bats are exposed to Pseudogymnoascus destructans, the fungal agent of white-nose syndrome. While pathological and epidemiological data suggest that Palearctic bats tolerate this infection, we lack knowledge about bat health under pathogen pressure. Here we report blood profiles, along with body mass index (BMI), infection intensity and hibernation temperature, in greater mouse-eared bats (Myotis myotis). We sampled three European hibernacula that differ in geomorphology and microclimatic conditions. Skin lesion counts differed between contralateral wings of a bat, suggesting variable exposure to the fungus. Analysis of blood parameters suggests a threshold of ca. 300 skin lesions on both wings, combined with poor hibernation conditions, may distinguish healthy bats from those with homeostatic disruption. Physiological effects manifested as mild metabolic acidosis, decreased glucose and peripheral blood eosinophilia which were strongly locality-dependent. Hibernating bats displaying blood homeostasis disruption had 2 °C lower body surface temperatures. A shallow BMI loss slope with increasing pathogen load suggested a high degree of infection tolerance. European greater mouse-eared bats generally survive P. destructans invasion, despite some health deterioration at higher infection intensities (dependant on hibernation conditions). Conservation measures should minimise additional stressors to conserve constrained body reserves of bats during hibernation.
- MeSH
- Ascomycota physiology MeSH
- Chiroptera blood microbiology physiology MeSH
- Hibernation * MeSH
- Body Mass Index MeSH
- Host-Pathogen Interactions * MeSH
- Skin Diseases blood microbiology pathology veterinary MeSH
- Mycoses blood microbiology pathology veterinary MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Because body temperature is tightly coupled to physiological function, hibernating animals entering deep torpor are typically immobile. We analysed thermal behaviour and locomotory activity of hibernating greater mouse-eared bats Myotis myotis and found two types of movement behaviour related to body temperature, i.e. movement at high fur temperature and at low fur temperatures (Tflow; <5°C). First Tflow movements appeared at the beginning of March and often occurred during long torpor bouts. In most cases, Tflow events represented slow displacements between clusters of bats. In several cases, however, departure or arrivals from and into clusters was also recorded without any elevation in body temperature. Distance travelled, flight duration and speed of locomotion during Tflow events was lower than in high fur temperature events. Such behaviour could allow bats to save energy long-term and prolong torpor bouts. Tflow movement in torpid bats significantly changes our understanding of basic hibernation principles and we strongly recommend further studies on the subject.
- MeSH
- Chiroptera physiology MeSH
- Behavior, Animal MeSH
- Hibernation MeSH
- Cold Temperature * MeSH
- Movement * MeSH
- Body Temperature * MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
