Tadarida Brasiliensis Research Articles

Changes in kinematics and aerodynamics over a range of speeds inTadarida brasiliensis, the Brazilian free-tailed bat

To date, wake measurements using particle image velocimetry (PIV) of bats in flight have studied only three bat species, all fruit and nectar feeders. In this study, we present the first wake structure analysis for an insectivorous bat. Tadarida brasiliensis, the Brazilian free-tailed bat, is an aerial hunter that annually migrates long distances and also differs strikingly from the previously investigated species morphologically. We compare the aerodynamics of T. brasiliensis with those of other, frugivorous bats and with common swifts, Apus apus, a bird with wing morphology, kinematics and flight ecology similar to that of these bats. The comparison reveals that, for the range of speeds evaluated, the cyclical pattern of aerodynamic forces associated with a wingbeat shows more similarities between T. brasiliensis and A. apus than between T. brasiliensis and other frugivorous bats.

Directed and Undirected Songs in Free-Tailed Bats, Implications for Mammalian Vocal Production

Event Abstract Back to Event Directed and Undirected Songs in Free-Tailed Bats, Implications for Mammalian Vocal Production Kirsten Bohn1, 2* and Michael Smotherman2 1 Florida International University, United States 2 Texas A&M, United States Most mammalian vocalizations are innate, inflexible and lack syntactical structure. Not surprisingly, the neurocircuitry of mammalian vocal production also appears relatively simple, being predominantly controlled by brainstem pattern generators. The Brazilian free-tailed bat, Tadarida brasiliensis, is unusual in that it is a mammal that sings like a bird – males produce hierarchically structured songs where specific syllables are combined to form phrases that vary in order and number from one rendition to the next. In songbirds it is known that song variability is generated by an avian analogue of the mammalian striatothalamic feedback pathway to cortex. To date, no mammalian vocalizations other than human speech are known to depend upon this striatothalamic pathway. If free-tailed bats can be shown to vary their songs in ways similar to songbirds, it may provide a unique example of how the striatothalamic circuitry contributes to mammalian vocal communication. The main goal of this project was to determine the contexts in which males sing and whether song flexibility varies with behavioral context. In the wild, males live in dense aggregations, usually in dark caves or crevices that preclude the use of visual cues. Given the environment in which singing occurs, we hypothesized that identifying the right auditory cues could be the key to characterizing batsong production. To test this, we conducted a set of playback experiments on a wild colony at Texas A&M that examined the relative effects of 1) echolocation calls that mimic a bat approaching the roost site and 2) unfamiliar male songs. We compared song responses to these two contextual stimuli with control periods of background noise. During playback experiments, we recorded 699 songs from an estimated 39 different males. Bats responded strongly and robustly to echolocation call stimuli – out of 50 sets of echolocation passes bats responded 74% of the time with 215 songs. During the same interval immediately preceding stimuli, bats sang only 6% of the time producing just three songs. Song responses were also incredibly rapid – initiating within 200 to 500 ms of stimulus onset. Song responses were highly specific to echolocation passes; bats did not respond to unfamiliar male songs even though there is no difference in the spectro-temporal structure of some song syllables and echolocation calls. Running the same experiments in our captive colony we found similar results – we rapidly triggered singing via playbacks of echolocation calls. Bats also sang in the absence of stimuli, but far less frequently. We labeled songs as directed songs if they were produced in response to an echolocation pass and undirected songs if they occurred during control periods. When we compared song structure between the two contexts we found a significant difference in song types and variability. Directed songs were significantly shorter and were more likely to contain buzzes than undirected songs. In conclusion, singing is rapidly triggered in free-tailed bats using echolocation calls and free-tailed bats vary songs across behavior contexts in a manner very similar to songbirds. Keywords: song, Mammal, Vocal-motor, bats, birdsong Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster (but consider for Participant Symposium) Topic: Social Behavior Citation: Bohn K and Smotherman M (2012). Directed and Undirected Songs in Free-Tailed Bats, Implications for Mammalian Vocal Production. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00068 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 04 Jul 2012; Published Online: 07 Jul 2012. * Correspondence: Dr. Kirsten Bohn, Florida International University, Miami, FL, United States, bohnkirsten@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Kirsten Bohn Michael Smotherman Google Kirsten Bohn Michael Smotherman Google Scholar Kirsten Bohn Michael Smotherman PubMed Kirsten Bohn Michael Smotherman Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Genetic diversity of Histoplasma capsulatum isolated from infected bats randomly captured in Mexico, Brazil, and Argentina, using the polymorphism of (GA)n microsatellite and its flanking regions

The genetic diversity of 47 Histoplasma capsulatum isolates from infected bats captured in Mexico, Brazil, and Argentina was studied, using sequence polymorphism of a 240-nucleotides (nt) fragment, which includes the (GA)n length microsatellite and its flanking regions within the HSP60 gene. Three human clinical strains were used as geographic references. Based on phylogenetic analyses of 240-nt fragments achieved, the relationships among H. capsulatum isolates were resolved using neighbour-joining and maximum parsimony methods. The tree topologies obtained by both methods were identical and highlighted two major clusters of isolates. Cluster I had three sub-clusters (Ia, Ib, and Ic), all of which contained Mexican H. capsulatum samples, while cluster II consisted of samples from Brazil and Argentina. Sub-cluster Ia included only fungal isolates from the migratory bat Tadarida brasiliensis. An average DNA mutation rate of 2.39 × 10−9 substitutions per site per year was estimated for the 240-nt fragment for all H. capsulatum isolates. Nucleotide diversity analysis of the (GA)n and flanking regions from fungal isolates of each cluster and sub-cluster underscored the high similarity of cluster II (Brazil and Argentina), sub-clusters Ib, and Ic (Mexico). According to the genetic distances among isolates, a network of the 240-nt fragment was graphically represented by (GA)n length haplotype. This network showed an association between genetic variation and both the geographic distribution and the ecotype dispersion of H. capsulatum, which are related to the migratory behaviour of the infected bats studied.

AnHcp100gene fragment revealsHistoplasma capsulatumpresence in lungs ofTadarida brasiliensismigratory bats

Histoplasma capsulatum was sampled in lungs from 87 migratory Tadarida brasiliensis bats captured in Mexico (n=66) and Argentina (n=21). The fungus was screened by nested-PCR using a sensitive and specific Hcp100 gene fragment. This molecular marker was detected in 81·6% [95% confidence interval (CI) 73·4-89·7] of all bats, representing 71 amplified bat lung DNA samples. Data showed a T. brasiliensis infection rate of 78·8% (95% CI 68·9-88·7) in bats captured in Mexico and of 90·4% (95% CI 75·2-100) in those captured in Argentina. Similarity with the H. capsulatum sequence of a reference strain (G-217B) was observed in 71 Hcp100 sequences, which supports the fungal findings. Based on the neighbour-joining and maximum parsimony Hcp100 sequence analyses, a high level of similarity was found in most Mexican and all Argentinean bat lung samples. Despite the fact that 81·6% of the infections were molecularly evidenced, only three H. capsulatum isolates were cultured from all samples tested, suggesting a low fungal burden in lung tissues that did not favour fungal isolation. This study also highlighted the importance of using different tools for the understanding of histoplasmosis epidemiology, since it supports the presence of H. capsulatum in T. brasiliensis migratory bats from Mexico and Argentina, thus contributing new evidence to the knowledge of the environmental distribution of this fungus in the Americas.

Selectivity for Spectral Motion as a Neural Computation for Encoding Natural Communication Signals in Bat Inferior Colliculus

This study examines the neural computations performed by neurons in the auditory system to be selective for the direction and velocity of signals sweeping upward or downward in frequency, termed spectral motion. We show that neurons in the auditory midbrain of Mexican free-tailed bats encode multiple spectrotemporal features of natural communication sounds. These features to which each neuron is tuned are nonlinearly combined to produce selectivity for spectral motion cues present in their conspecific calls, such as direction and velocity. We find that the neural computations resulting in selectivity for spectral motion are analogous to models of motion selectivity studied in vision. Our analysis revealed that auditory neurons in the inferior colliculus (IC) are avoiding spectrotemporal modulations that are redundant across different bat communication signals and are specifically tuned for modulations that distinguish each call from another by their frequency-modulated direction and velocity, suggesting that spectral motion is the neural computation through which IC neurons are encoding specific features of conspecific vocalizations.

Cloning, expression and antiviral activity of IFNγ from the Australian fruit bat, Pteropus alecto

Bats are natural reservoir hosts to a variety of viruses, many of which cause morbidity and mortality in other mammals. Currently there is a paucity of information regarding the nature of the immune response to viral infections in bats, partly due to a lack of appropriate bat specific reagents. IFNγ plays a key role in controlling viral replication and coordinating a response for long term control of viral infection. Here we describe the cloning and expression of IFNγ from the Australian flying fox, Pteropus alecto and the generation of mouse monoclonal and chicken egg yolk antibodies specific to bat IFNγ. Our results demonstrate that P. alecto IFNγ is conserved with IFNγ from other species and is induced in bat splenocytes following stimulation with T cell mitogens. P. alecto IFNγ has antiviral activity on Semliki forest virus in cell lines from P. alecto and the microbat, Tadarida brasiliensis. Additionally recombinant bat IFNγ was able to mitigate Hendra virus infection in P. alecto cells. These results provide the first evidence for an antiviral role for bat IFNγ in vitro in addition to the application of important immunological reagents for further studies of bat antiviral immunity.

Cutaneous water loss and lipids of the stratum corneum in two syntopic species of bats

The lipid matrix of the stratum corneum (SC), the outer layer of the epidermis of mammals and birds, constitutes the barrier to diffusion of water vapor through the skin. The lipids of the SC are structured in the intercellular spaces of the mammalian epidermis in ordered layers, called lamellae, which have been postulated to prevent water loss. Lipids in the mammalian SC are mainly cholesterol, free fatty acids and ceramides, the latter forming the structural support for the lamellae. However, knowledge on how the lipid composition of the SC alters cutaneous water loss (CWL) in mammals is rudimentary, and is largely derived from studies on laboratory animals and humans. We measured CWL of individuals of two species of syntopic bats, Tadarida brasiliensis and Myotis velifer. In the first study of its kind on wild mammals, we correlated CWL with the lipid composition of the SC, measured using thin layer chromatography and high performance liquid chromatography coupled with atmospheric pressure photoionization mass spectrometry. Surface-specific CWL was 20.6% higher in M. velifer than in T. brasiliensis, although differences were not significant. Compared with individuals of M. velifer, individuals of T. brasiliensis had more classes, and a higher proportion, of polar ceramides in the SC, a feature associated with lower CWL. Individuals of T. brasiliensis also had a class of non-polar ceramides that presumably spans the lamellae and gives more cohesiveness to the lipid matrix of the SC. We conclude that qualitative and quantitative modifications of the lipid composition of the SC contribute to regulate CWL of these two species of bats.

Naturally Acquired Rabies Virus Infections in Wild-Caught Bats

The study of a zoonotic disease requires an understanding of the disease incidence in animal reservoirs. Rabies incidence in bats submitted to diagnostic laboratories does not accurately reflect the true incidence in wild bat populations as a bias exists for testing bats that have been in contact with humans or pets. This article details the rabies incidence in two species of bats collected from natural settings without such bias. In this study, brain smears from 0.6% and 2.5% of wild-caught and apparently healthy Tadarida brasiliensis and Eptesicus fuscus, respectively, were positive for rabies virus (RV) antigen. Conversely, 92% of the grounded T. brasiliensis were positive for RV. Serology performed on captive colony and sick bats reveal an immune response to rabies. This work illustrates the complex interplay between immunity, disease state, and the conundrum of RV maintenance in bats.

BASAL GANGLIA REGULATE BAT VOLUME AGAINST NOISE

We're not the only animals that begin shouting when we enter a noisy environment. Bats also adjust their calls to hear faint echoes above a noisy background. Although little was known about the neural pathways that control bats' vocal versatility, Michael Smotherman and colleagues from Texas A&M University, USA, explain that the basal ganglia – a suite of forebrain nuclei – are involved in vocal adjustments in other vertebrates through the action of a neurotransmitter, dopamine. Could the basal ganglia and dopamine have a function in controlling bats' echolocation calls? Knowing that a neurotoxin, 1-methyl-4-phenylpyridine (MPTP) can affect basal ganglia dopamine levels in other animals, Smotherman and his team decided to test the effect of the compound on free-tailed bats (Tadarida brasiliensis) to find out if dopamine and the basal ganglia are involved in controlling their voices (p. 3238).Collecting bats from a local roost, the team recorded the animals' echolocation calls in both a silent and noisy environment and found that, in the noisy environment, the bats raised their voices and lengthened each chirrup to be heard above the racket. Then they gave the bats a small dose of MPTP and, after confirming that the toxin did not affect the animals' movements, the team tested their ability to adjust their calls in a loud environment. This time, the bats were unable to adjust their voices to compensate for the acoustic noise. So, the basal ganglia are involved in controlling the bat's voices in response to interference from background sound, but how?Wondering how MPTP had affected the bats' dopamine levels, the team measured dopamine in the animals' brains and were surprised to see that, instead of falling, the level had risen 4-fold. Then the team tested which dopamine receptor is involved in mediating vocal control. Administering low doses of agonist compounds – which also bind to dopamine receptors – the team found that quinpirole, which binds type-2 dopamine receptors, produced the same changes in the bats' vocal response as the dopamine-enhancing MPTP.So, basal ganglia are involved in bat vocal control, allowing the echolocating animals to adjust their calls in response to noisy backgrounds via type-2 dopamine receptor pathways. The team hope to find out more about the role of dopamine and the basal ganglia in bat and mammalian vocal control.

Mapping vocalization-related immediate early gene expression in echolocating bats

Recent studies of spontaneously vocalizing primates, cetaceans, bats and rodents suggest these animals possess a limited but meaningful capacity to manipulate the timing and acoustic structure of their vocalizations, yet the neural substrate for even the simplest forms of vocal modulation in mammals remains unknown. Echolocating bats rapidly and routinely manipulate the acoustic structure of their outgoing vocalizations to improve echolocation efficiency, reflecting cognitive rather than limbic control of the vocal motor pathways. In this study, we used immunohistochemical localization of immediate early gene ( c-fos) expression to map neural activity in the brains of spontaneously echolocating stationary Mexican free-tailed bats. Our results support the current model of vocal control obtained largely through microstimulation studies, but also provide evidence for the contributions of two novel regions, the dorsolateral caudate nucleus and mediodorsal thalamic nucleus, which together suggest a striatothalamic feedback loop may be involved in the control of echolocation pulse production. Additionally, we found evidence of a motivation pathway, including the lateral habenula, substantia nigra pars compacta, and raphe nuclei. These data provide novel insights into where and how mammalian vocalizations may be regulated by sensory, contextual and motivational cues.

Rabies diagnosis and serology in bats from the State of São Paulo, Brazil

Bats are one of the most important reservoirs and vectors of the rabies virus in the world. From 1988 to 2003, the Zoonosis Control Center in São Paulo City performed rabies diagnosis on 5,670 bats by direct immunofluorescent test and mouse inoculation test. Blood samples were collected from 1,618 bats and the sera were analyzed using the rapid fluorescent focus inhibition test to confirm rabies antibodies. Forty-four (0.8%) bats were positive for rabies. The prevalence of rabies antibodies was 5.9% using 0.5IU/ml as a cutoff. Insectivorous bats (69.8%) and bats of the species Molossus molossus (51.8%) constituted the majority of the sample; however, the highest prevalence of antibodies were observed in Glossophaga soricina (14/133), Histiotus velatus (16/60), Desmodus rotundus (8/66), Artibeus lituratus (5/54), Nyctinomops macrotis (3/23), Tadarida brasiliensis (3/48), Carollia perspicillata (3/9), Eumops auripendulus (2/30), Nyctinomops laticaudatus (2/16), Sturnira lilium (2/17) and Eumops perotis (1/13). The prevalence of rabies antibodies was analyzed by species, food preference and sex. The expressive levels of antibodies associated with the low virus positivity verified in these bats indicate that rabies virus circulates actively among them.

Population growth of Mexican free-tailed bats (Tadarida brasiliensis mexicana) predates human agricultural activity

BackgroundHuman activities, such as agriculture, hunting, and habitat modification, exert a significant effect on native species. Although many species have suffered population declines, increased population fragmentation, or even extinction in connection with these human impacts, others seem to have benefitted from human modification of their habitat. Here we examine whether population growth in an insectivorous bat (Tadarida brasiliensis mexicana) can be attributed to the widespread expansion of agriculture in North America following European settlement. Colonies of T. b. mexicana are extremely large (~106 individuals) and, in the modern era, major agricultural insect pests form an important component of their food resource. It is thus hypothesized that the growth of these insectivorous bat populations was coupled to the expansion of agricultural land use in North America over the last few centuries.ResultsWe sequenced one haploid and one autosomal locus to determine the rate and time of onset of population growth in T. b. mexicana. Using an approximate Maximum Likelihood method, we have determined that T. b. mexicana populations began to grow ~220 kya from a relatively small ancestral effective population size before reaching the large effective population size observed today.ConclusionsOur analyses reject the hypothesis that T. b. mexicana populations grew in connection with the expansion of human agriculture in North America, and instead suggest that this growth commenced long before the arrival of humans. As T. brasiliensis is a subtropical species, we hypothesize that the observed signals of population growth may instead reflect range expansions of ancestral bat populations from southern glacial refugia during the tail end of the Pleistocene.

Extreme Periodontal Disease in a Brazilian Free-Tailed Bat (Molossidae: Tadarida brasiliensis) from Eastern Texas

Abstract A male Brazilian free-tailed bat (Tadarida brasiliensis), collected from a colony in Huntsville, Walker County, Texas, had severe periodontal disease resulting in extensive loss of teeth. Although demonstrating normal activity and a healthy appearance, this individual had only eight teeth: normal complement is 30–32 teeth. The remaining teeth appeared to be sufficient for this individual to adequately process food and maintain an average body weight as reported for this species.

Mammalia, Chiroptera, Molossidae, Tadarida brasiliensis I. Geoffroy, 1824: distribution extension

Tadarida brasiliensis is one of the most widely distributed mammalian species in America. We report the southernmost continental record for this species in Rada Tilly, province of Chubut, Argentina, extending its range ca. 390 km to the south.

Isolation of Histoplasma capsulatum from bats in the urban area of São Paulo State, Brazil

The presence of bats in caves, attics, ceilings, and roofs is important epidemiologically as they can increase the chance of human acquisition of pathogens, including Histoplasma capsulatum. Brazilian urban areas contain many species of bats, especially insectivorous bats, that are attracted by a wide range of readily available food and shelter. From August 2003 to December 2008, we analysed 2427 bats in the São Paulo State region. Homogenates of the livers and spleens of the bats were plated on specific medium to identify animals infected with H. capsulatum. The fungus was isolated from 87 bats (3·6%). The infected bats were identified as Molossus molossus (74), Nyctinomops macrotis (10), Tadarida brasiliensis (1), Molossus rufus (1) and Eumops glaucinus (1), all insectivorous species. The data presented are a relevant contribution to the epidemiology of H. capsulatum in densely populated urban areas such as in São Paulo State, especially since histoplasmosis is not included in the mandatory disease notification system.

Variation in Physiological Stress between Bridge- and Cave-Roosting Brazilian Free-Tailed Bats

Since the late 1980s, Brazilian free-tailed bats (Tadarida brasiliensis) have increasingly used bridges as roosts in the southern United States. We examined differences in blood cortisol levels, body condition, and parasite load, as measures of physiological stress in bats roosting in bridges and bats roosting in caves. We collected data during three periods, coinciding with female phases of reproduction. For all measures, bats were captured during the nightly emergence from the roost and immediately sampled. Cortisol levels were significantly higher during pregnancy and lactation and in individuals with lower body-condition scores (length of forearm to mass ratio) and significantly higher in bats roosting in caves than in those roosting in bridges. Thus, we concluded that individuals of this species that roost in bridges are not chronically stressed and seem to be unaffected by human activities present at bridges. This is a rare documented instance where a human-dominated environment does not appear to be adversely affecting the physiological health of a free-ranging animal.

Bats

Bats

New report of parasite-fauna of the free-tailed bat (Tadarida brasiliensis, Geoffroy, 1824) in Chile

One hundred and ninety five specimens of free tailed bat (Tadarida brasiliensis) obtained from two regions of Chile were analized to determine parasite infection. From those specimens the endoparasites identified were: Trematoda: Acanthatrium lunatum, Limatuoides limatulus and Paralecithodendrium carlsbadensis; Cestoda: Vampirolepis sp.; Nematoda: Nochtia pilosus and Anoplostrongylus paradoxus. The ectoparasites identified were Chiroptonyssus robustipes, Ewingnana inaequalis and Notoedres lasionycteris all of them are acari species. Even thought the bat specimens are from the same species on both survey sites, the results differ for each site when the parasite species identified are compared.

Thermoregulation during Flight: Body Temperature and Sensible Heat Transfer in Free-Ranging Brazilian Free-Tailed Bats (Tadarida brasiliensis)

Bat wings are important for thermoregulation, but their role in heat balance during flight is largely unknown. More than 80% of the energy consumed during flight generates heat as a by-product, and thus it is expected that bat wings should dissipate large amounts of heat to prevent hyperthermia. We measured rectal (T(r)) and surface (T(s)) temperatures of Brazilian free-tailed bats (Tadarida brasiliensis) as they emerged from and returned to their daytime roosts and calculated sensible heat transfer for different body regions (head, body, wings, and tail membrane). Bats' T(r) decreased from 36.8°C during emergence flights to 34.4°C during returns, and T(s) scaled positively with ambient temperature (T(a)). Total radiative heat loss from bats was significantly greater for a radiative sink to the night sky than for a sink with temperature equal to T(a). We found that free-ranging Brazilian free-tailed bats, on average, do not dissipate heat from their wings by convection but instead dissipate radiative heat (L) to the cloudless night sky during flight ([Formula: see text] W). However, within the range of T(a) measured in this study, T. brasiliensis experienced net heat loss between evening emergence and return flights. Regional hypothermia reduces heat loss from wings that are exposed to potentially high convective fluxes. Additional research is needed to establish the role of wings in evaporative cooling during flight in bats.

Intracellular Recordings Reveal Novel Features of Neurons That Code Interaural Intensity Disparities in the Inferior Colliculus

Many cells in the inferior colliculus (IC) are excited by contralateral and inhibited by ipsilateral stimulation and are thought to be important for sound localization. These excitatory-inhibitory (EI) cells comprise a diverse group, even though they exhibit a common binaural response property. Previous extracellular studies showed the diversity results from different circuits that generate the same EI property among the IC population, where some inherit the property from a lower nucleus, some are formed de novo in the IC, and others inherit EI features that are modified by inhibitory circuits. Here we evaluated the differential circuitry by recording inputs (postsynaptic potentials) and outputs (spikes) with in vivo whole-cell recordings from the IC of awake Mexican free-tailed bats. We show that in a minority of EI cells, either they inherited their binaural property from a lower binaural nucleus or the EI property was created in the IC via inhibitory projections from the ipsilateral ear, features consistent with those observed in extracellular studies. However, in a majority of EI cells, ipsilateral signals evoked subthreshold EPSPs that behaved paradoxically in that EPSP amplitudes increased with intensity, even though binaural signals with the same ipsilateral intensities generated progressively greater spike suppressions. We propose circuitry that can account for the responses we observed and suggest that the ipsilaterally evoked EPSPs could influence the responsiveness of IC cells to dynamic signals with interaural intensity disparities that change over time, such as moving sound sources or multiple sounds that occur in complex acoustic environments.