Project description:Bats can harbor many pathogens without showing disease. However, the mechanisms by which bats resolve these infections or limit pathology remain unclear. To illuminate the bat immune response to coronaviruses, viruses with high public health significance, we will use serum proteomics to assess broad differences in immune proteins of uninfected and infected vampire bats (Desmodus rotundus). In contrast to global profiling techniques of blood such as transcriptomics, proteomics provides a unique perspective into immunology, as the serum proteome includes proteins from not only blood but also those secreted from proximal tissues. Here, we expand our recent work on the serum proteome of wild vampire bats (Desmodus rotundus) to better understand CoV pathogenesis. Across 19 bats sampled in 2019 in northern Belize with available sera, we detected CoVs in oral or rectal swabs from four individuals. We used data independent acquisition-based mass spectrometry to profile and compare the undepleted serum proteome of these 19 bats. These results will provide much needed insight into changes in the bat serum proteome in response to coronavirus infection.
Project description:Bats are increasingly studied as model systems for longevity and as natural hosts to some virulent viruses. Yet our ability to characterize immune mechanisms of viral tolerance and to quantify infection dynamics in wild bats is often limited by small sample volumes and few species-specific reagents. To address this, we demonstrate how proteomics can overcome these limitations by using data-independent acquisition-based shotgun proteomics (i.e., bottom-up proteomics) to survey the serum proteome of 17 vampire bats (Desmodus rotundus) from Belize. We focused this work on vampire bats, a species that has an obligate diet of blood and feeds on prey as diverse as sea lions, tapirs, livestock, and even humans, providing numerous opportunities for transmission of viruses (e.g., rabies virus, adenovirus, herpesvirus) to and from these recipient hosts. Using just 2 μL of sample and relatively short separations of undepleted serum digests, we identified 361 proteins across five orders of magnitude. We also used known bat virus proteomes to identify Rh186 from Macacine herpesvirus 3 and ORF1a from Middle East respiratory syndrome-related coronavirus, indicating that mass spectrometry-based techniques show promise for pathogen detection. Our results demonstrate the feasibility and capabilities of serum proteomic analyses in wild bats, including possibilities to simultaneously detect host immunological components and viral infection as well as to establish preliminary ranges of vampire bat proteins for comparison with other mammalian blood proteomes. Overall, these results can be used to design targeted mass-spectrometry assays to quantify immunological markers and detect pathogens. More broadly, our findings also highlight the application of proteomics in advancing wildlife immunology and pathogen surveillance.
Project description:Bats harbour various viruses without severe symptoms and act as natural reservoirs. This tolerance of bats toward viral infections is assumed to be originated from the uniqueness of their immune system. However, how the innate immune response varies between primates and bats remains unclear. To illuminate differences in innate immune responses among animal species, we performed a comparative single-cell RNA-sequencing analysis on peripheral blood mononuclear cells (PBMCs) from four species including Egyptian fruit bats inoculated with various infectious stimuli.
Project description:Hearing mediates many behaviors critical for survival in echolocating bats, including foraging and navigation. Although most mammals are susceptible to progressive age-related hearing loss, the evolution of biosonar, which requires the ability to hear low-intensity echoes from outgoing sonar signals, may have selected against the development of hearing deficits in bats. Many echolocating bats exhibit exceptional longevity and rely on acoustic behaviors for survival to old age; however relatively little is known about the aging bat auditory system. In this study, we used DNA methylation to estimate the ages of wild-caught big brown bats (Eptesicus fuscus) and measured hearing sensitivity in young and aging bats using auditory brainstem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs). We found no evidence for hearing deficits in bats up to 12.5 years of age, demonstrated by comparable thresholds and similar ABR and DPOAE amplitudes across age groups. We additionally found no significant histological evidence for cochlear aging, with similar hair cell counts, afferent, and efferent innervation patterns in young and aging bats. Here we demonstrate that big brown bats show minimal evidence for age-related hearing loss and therefore represent informative models for investigating mechanisms that may preserve hearing function over a long lifetime.
Project description:Bats are the only mammals capable of self-powered flying. Many bat species hibernate in winter. A reversible control of cerebral activities is critical for bats to accommodate a repeated torpor-arousal cycle during hibernation. Little is known about the molecular mechanism that regulates neuronal activities in torpid bats. In this study, brain proteins were fractionated and compared between torpid and active Rhinolophus ferrumequinum bats.
Project description:As the only truly flying mammals, bats use their unique wing formed from elongated digits connected by membranes to power their flight. The forelimb of bats consists of four elongated digits (digits II-V) and one shorter digit (digit I) that is morphologically similar to the hindlimb digits. Elongation of bat forelimb digits is thought to results from changes in the temporal and spatial expression of a number of developmental genes. As a result, comparing gene expression profiles between short and elongated digit morphologies of the fore- and hindlimbs may elucidate the molecular mechanisms underlying digit elongation in bats. Here, we performed a large-scale analysis of gene expression of forelimb digit I, forelimb digits II-V, and all five hindlimb digits in Myotis ricketti using digital gene expression tag profiling approach. Results of this study not only implicate several developmental genes as robust candidates underlying digit elongation in bats, but also provide a better understanding of the genes involved in autopodial development in general. A large-scale analysis of gene expression of 3 different parts of autopods in Myotis ricketti using digital gene expression tag profiling approach.
Project description:The only freely flying mammals, bats, develop a pair of dramatically elongated hands and broad wing membranes. It is hypothesized that alterations of many gene expressions result in the bat wing formation. However, it remains to be proved. Here, by mRNA-seq, we found that hundreds of genes are significantly high expressed in the elongating forelimb digits. mRNA-seq data of 14 autopod samples from embryonic bats (Miniopterus schreibersii) were obtained by Illumina HiSeq 2000.
Project description:Bats harbor high-impact zoonotic viruses in absence of clinical disease, which has been recently associated with unique features of their immune system. They seem to restrict inflammation and possibly limit disease manifestation to a minimum. In-depth characterization of cellular immunity in bats is yet largely missing, and imprinting of age and development on immune cell compartments remains unexplored. We employed single-cell transcriptomics and established immunostaining panels to investigate the immune cell populations peripheral blood for juvenile and adult Egyptian Rousette bats (ERB).
Project description:Unfolded protein accumulation in the lumen of endoplasmic reticulum (ER) induced by cold exposure is termed UPRER. Some mammals hibernate to overcome cold winter. We investigated whether hibernating bats are under UPRER and activate Akt, Nrf2, and NF-κB signaling pathways that are critical for cell survival against cold. Results of Western blotting showed that several UPRER marker proteins such as PERK and ATF4 had a higher abundance in torpid than in active bats. Cellular redistribution of GRP78 and a lower degree of binding between PERK and GRP78 were also seen in torpid bats, suggesting the occurrence of UPRER. Results also showed that torpid bats had a higher amount of p-Akt (Ser473), a higher ratio of p-Akt (Ser473)/Akt, a lower amount of Keap1/Nrf2 and NF-κB (p65)/I-κBα complexes, and a higher degree of NF-κB (p65) nuclear translocation than active bats, indicating simultaneous activation of Akt, Nrf2, and NF-κB during hibernation. Evidence of such activation was not observed in fasted, cold-treated, or normal mice. Using PPI network and IPA analyses, we examined the proteomes of liver and liver mitochondria of bats and found a global metabolic adjustment and survival adaptation in response to UPRER in hibernating bats. Our data provide the first molecular evidence of a complex cross talk involving Akt, Nrf2, and NF-κB via the PERK-EIF2-ATF4 regulatory axis under UPRER in bats to ensure their survival during hibernation.
Project description:Vampire bats and snakes have taken thermosensation to the extreme by developing specialized systems for detecting infrared radiation. As such, these creatures provide a window into the molecular and genetic mechanisms underlying evolutionary tuning of thermoreceptors in a species or cell type specific manner. In each case, robust thermal sensitivity likely reflects specialized anatomical features of infrared sensing pit organs, as well as intrinsic heat sensitivity of trigeminal nerve fibers that innervate these structures. Here we show that vampire bats use a molecular strategy involving alternative splicing of the TRPV1 gene to generate a channel specifically within trigeminal ganglia that has a reduced thermal activation threshold. Selective expression of splicing factors in trigeminal, but not dorsal root ganglia, together with unique organization of the vampire bat TRPV1 gene underlies this mechanism of sensory adaptation. Comparative genomic analysis of the TRPV1 locus supports phylogenetic relationships within the proposed Pegasoferae clade of mammals. Gene expression measurements implicate a TRPV1 splice isoform as the heat-sensitive channel in vampire bats