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At least 829 records · Page 46Linked to original sources
PubMed1985

A deoxyglucose study on auditory responses in the bat Rhinolophus rouxi.

Responses in the auditory system of the echolocating bat Rhinolophus rouxi were mapped with [3H]deoxyglucose (DG) autoradiography. After unilateral stimulation with the constant frequency component of the individual bat's echolocation call, stimulus-related DG uptake occurred contralaterally in the dorsolateral and the ventromedial parts of the inferior colliculus, in the ventral medial geniculate body and in the contralateral neocortex. Unilateral 50 kHz-stimulation gave rise to a weakly activated lamina in the dorsolateral contralateral inferior colliculus. The distribution of frequency-evoked DG uptake within the inferior colliculus agrees with electrophysiological findings on an acoustic fovea in the auditory pathway of echolocating bats.

Acoustic Stimulation↗
PubMed1987

The efferent cochlear projections of the superior olivary complex in the mustached bat.

Following the placement of horseradish peroxidase in the scala tympani, labeled neurons were found in the ipsilateral interstitial nucleus (INT) and throughout the ipsilateral and contralateral dorsomedial periolivary nuclei (DMPO). The neurons in the INT were morphologically distinct from those in the DMPO. The INT neurons formed a thin shell over the lateral superior olivary nucleus (LSO) and their dendrites extended into the body and hilar region. The DMPO neurons had long, tapering dendrites that extended in every direction. Data indicate that the crossed fibers in the floor of the ventricle arise entirely from the DMPO while uncrossed olivocochlear fibers originate in the INT and DMPO. It was estimated that 75% of the efferent fibers arise from the INT and 25% from the DMPO. Approximately 70% of the efferent neurons in each DMPO project to the contralateral cochlea via the crossed olivocochlear bundle. The number of olivocochlear neurons associated with each ear was determined to be approximately 1585. This number is similar to that found in cats and guinea pigs, but the number of neurons per unit length of the basilar membrane is considerably higher in the mustached bat than in other species examined to date. The compact, restricted locations of the neurons in the INT and DMPO in the mustached bat are different from those described for most other mammals and the arrangement in the mustached bat offers advantages over other species for future anatomical and physiological studies.

Animals↗
PubMedDate not supplied

The receptor and neuron distribution in the cochlea of the bat, Taphozous kachhensis.

Cochlear receptors and spiral ganglion neurons in the inner ear of the bat, Taphozous kachhensis of the family Emballonuridae, were quantitatively analyzed on the basis of surface specimen technique, histological sections, and three-dimensional computer reconstruction. The length of the basilar membrane was 12.1 (+/- 0.4) mm. There were about 23,000 neurons in the spiral ganglion and about 1430 inner hair cells and 4635 outer hair cells in the organ of Corti. Cochlear neurons had two density maxima, one basal and one apical. Inner hair cells had basically the same distribution but less pronounced. Outer hair cells had only one density maximum in the apical region corresponding to the respective maxima of inner hair cells and cochlear neurons. Basal density maxima of inner hair cells and neurons are most probably involved in the analysis of echolocation signals, and presumably correlated with maximum sensitivity of the auditory system. A comparison with the bat, Nyctalus noctula of the family Vespertilionidae revealed a conspicuous similarity in some quantitative aspects of the cochlear structure. These particular similarities may be looked upon as convergent adaptations given by similar flight, hunting, and echolocation strategies in both bat species.

Animals↗
PubMed1988

Directionality of sound pressure transformation at the pinna of echolocating bats.

The directionality of sound pressure transformation at the pinna of three species of bats was studied by measuring the sound pressure level of a tone (25 45 65 and 85 kHz) at the tympanic membrane as a function of azimuth and elevation of the sound source under free-field conditions. The tympanic sound pressure level varied with location of the sound source. The directionality of sound pressure transformation pattern of the pinna of each bat was studied by plotting isopressure contours. The area within each isopressure contour decreased with increasing tonal frequency. For each tonal frequency, the point of maximal sound pressure was always located in the frontal ipsilateral sound field. This point shifted medially with increasing tonal frequency along the horizontal plane in all species tested, but it shifted in a species-specific manner along the vertical plane. Removal or distortion of the pinna and tragus resulted in either uncircumscribed or irregular isopressure contours for all tonal frequencies tested. Acoustic pressure gain of the external ear reached 16-23 dB for frequencies at 15-18 kHz. The importance of the external ear to the directionality of the bat's echolocation system is discussed.

Acoustics↗
PubMed1989

Evoked potential correlates of echolocation in the mustached bat, Pteronotus p. parnellii.

The biosonar signals of the greater mustached bats are characterized by a long constant frequency component that is preceded and terminated by frequency modulated components. It has generally been concluded that the terminal FM (TFM) is important for target ranging while the initial FM (IFM), or beginning of the signal, is relatively insignificant. With the aid of chronically implanted electrodes, acoustically evoked brainstem potentials were recorded from bats during simulated flight on a pendulum and when targets were placed at fixed distances from the bat's head. Distinct pulse- and echo-evoked potentials were recorded in relation to the onset of both the IFM and TFM, or the onset of the CF when no IFM was present. Echo-evoked potentials were often as high in amplitude as pulse-evoked potentials and the timing of the IFM- and TFM-pulse and echo-evoked potentials seemed to accurately reflect target distance. Data indicate that the IFM, or signal onset, must be a significant part of the echo even though it is usually faint, overlaps the intense outgoing CF component, and returns to the ear when the middle ear muscles are contracting.

Animals↗
PubMed1993

The dorsal nucleus of the lateral lemniscus in the mustache bat: monaural properties.

Neurons in the mustache bat dorsal nucleus of the lateral lemniscus (DNLL) were examined in response to monaural stimulation. There are six main findings of this study. First, the mustache bat DNLL is tonotopically organized. Second, EI cells are the predominant aural type and comprise about 80% of DNLL neurons, whereas monaural and EE cells are far less numerous. Third, the majority of DNLL neurons have either monotonic or weakly nonmonotonic rate-intensity functions. Fourth, a chopping pattern is evoked by contralateral stimulation in 58% of DNLL neurons and is the predominant temporal response pattern. Fifth, neurons with different aural properties tend to exhibit different temporal response patterns: EI cells are largely choppers, while EO and EE cells are more often primarylike or primarylike-with-notch. Sixth, the sustained responses of EE units to contralateral stimulation differs dramatically from their onset responses to ipsilateral stimulation. Here we have demonstrated that although a large proportion of mustache bat DNLL neurons are EI choppers, the DNLL nonetheless contains a heterogeneous population of neurons based on physiological responses to pure tones.

Acoustic Stimulation↗
PubMed1994

Temporal auditory summation in the echolocating bat, Tadarida brasiliensis.

Auditory thresholds improve with increasing signal duration within the maximum integration time of the auditory system, a phenomenon called temporal summation. The temporal summation function is a basic characteristic of particular relevance for bat sonar, as it determines the ability to detect targets with short echolocation calls. Temporal summation was studied in 6 Mexican free-tailed bats (Tadarida brasiliensis) in a forced two-choice behavioural test. Masked auditory thresholds for 40-kHz test tone pulses with durations between 2 ms and 400 ms were determined in broadband noise of two different spectrum levels (-18 dB, +17 dB). At both masker levels, thresholds decreased by considerably more than 10 dB per decade of duration. The time constants of the summation functions, which are a measure of the maximum integration time, shortened significantly with increasing masker level from 62 ms to 14 ms. The steep summation functions are only partly accounted for by spectral splatter. This suggests that the bats are capable of a neural overintegration of sound intensity. Finally, it is shown that such short time constants are typical for echolocating animals, and the implications of the found summation functions for echolocation are considered.

Acoustic Stimulation↗
PubMed1990

Demyelinisation in the spinal cord of vitamin B12 deficient fruit bats.

1. Vitamin B12 deficiency induced in the fruit bat by a combination of dietary deprivation and exposure to nitrous oxide (N2O) is accompanied by profound neurological impairment, thus providing an experimental model for the study of vitamin B12 neuropathy. 2. Electron microscopy of the spinal cord of vitamin B12 deficient bats shows marked changes in the myelin of the posterior columns in the form of distension, separation and vacuolation of myelin lamellae similar to the changes described in the dietary induced B12 deficient monkey model. 3. No equivalent change occurred in bats exposed to N2O and supplemented with vitamin B12.

Animals↗
PubMedDate not supplied

A reduced panel of anti-nucleocapsid monoclonal antibodies for bat rabies virus identification in Europe.

A reduced panel of 4 anti-nucleocapsid monoclonal antibodies (mAb) was set up to distinguish viruses of terrestrial mammal origin from viruses of bat origin in Europe. Four additional mAb were necessary to identify each one of the four serotypes of lyssavirus. These 8 mAb were selected out of 25 mAb secreted by hybridomas obtained from mice immunized with either serotype 1 lyssavirus (rabies virus PV4) or serotype 3 lyssavirus (Mokola). They were screened with 32 viruses representative of the four lyssavirus serotypes and the two types of European bat lyssavirus. The panel was tested by immunofluorescence assay with 25 cell-culture-adapted European wildlife isolates and in routine rabies identification with 65 rabid animal brain smears. Two isolates from Eptesicus serotinus in France were identified as European bat lyssavirus 1 with the reduced panel.

Animals↗
PubMed2004

Up-regulation of fatty acid-binding proteins during hibernation in the little brown bat, Myotis lucifugus.

Hibernating animals rely primarily on lipids throughout winter as their primary fuel source, thus it is hypothesized that an increase in genes and proteins relating to lipid transport will increase accordingly. The cloning and expression of heart type fatty acid-binding protein (h-fabp) from a mammalian hibernator, the little brown bat Myotis lucifugus, is presented. Northern blot analysis revealed that transcript levels of h-fabp were significantly higher during hibernation in brown adipose tissue and skeletal muscle compared with levels in euthermic bats. Similarly, heterologous probing with rat adipose type a-fabp found 3.9-fold higher levels of a-fabp transcripts in brown adipose from hibernating animals. Levels of A- and H-FABP protein were quantified in tissues of euthermic versus hibernating animals by Western blotting. A-FABP was 4-fold higher in brown adipose of hibernating, compared with euthermic bats, whereas H-FABP was significantly higher in hibernator brown adipose, heart and skeletal muscle. The present work implicates FABPs as important elements related to the hibernating state in mammals; alterations in gene and protein expression along with amino acid substitutions are shown. These likely contribute to optimizing the function of FABPs at the low body temperatures (near 0 degrees C) experienced in the hibernating state.

Amino Acid Sequence↗
PubMed2005

Technetium-99m labelled integrated tropane-BAT as a potential dopamine transporter tracer.

To reduce the molecular weight of 99mTc-labelled tropanes with the aim to enhance the passage over the blood-brain barrier, a so-called integrated tropane-BAT construct was developed. For this purpose a mercaptoethyl substituent was attached to the amine nitrogen atom of a nortropane precursor and the methyl carboxylate in 2beta-position was converted to a 2-mercaptoethylaminomethylene substituent. This integrated tropane-BAT construct could be labelled efficiently (85-90%) with technetium-99m. Results of LC-MS analysis of the tracer agent support the assumed structure. Biodistribution studies in normal rats (n=3) showed a slightly higher brain uptake for the new tracer agents as compared to 99mTc-TRODAT-1. These results indicate that further biological evaluation of the integrated 99mTc-tropane-BAT is warranted.

Animals↗
PubMed2003

Neurobiology of echolocation in bats.

Echolocating bats (sub-order: Microchiroptera) form a highly successful group of animals, comprising approximately 700 species and an estimated 25% of living mammals. Many echolocating bats are nocturnal predators that have evolved a biological sonar system to orient and forage in three-dimensional space. Acoustic signal processing and vocal-motor control are tightly coupled, and successful echolocation depends on the coordination between auditory and motor systems. Indeed, echolocation involves adaptive changes in vocal production patterns, which, in turn, constrain the acoustic information arriving at the bat's ears and the time-scales over which neural computations take place.

Animals↗
PubMed2005

Geographical distribution of genetic polymorphism of the pathogen Histoplasma capsulatum isolated from infected bats, captured in a central zone of Mexico.

Fourteen Histoplasma capsulatum isolates recovered from infected bats captured in Mexican caves and two human H. capsulatum reference strains were analyzed using random amplification of polymorphic DNA PCR-based and partial DNA sequences of four genes. Cluster analysis of random amplification of polymorphic DNA-patterns revealed differences for two H. capsulatum isolates of one migratory bat Tadarida brasiliensis. Three groups were identified by distance and maximum-parsimony analyses of arf, H-anti, ole, and tub1 H. capsulatum genes. Group I included most isolates from infected bats and one clinical strain from central Mexico; group II included the two isolates from T. brasiliensis; the human G-217B reference strain from USA formed an independent group III. Isolates from group II showed diversity in relation to groups I and III, suggesting a different H. capsulatum population.

Animals↗
PubMed2006

The role of GABAergic inhibition in shaping duration selectivity of bat inferior collicular neurons determined with temporally patterned sound trains.

A previous study has shown that duration selectivity of neurons in the inferior colliculus (IC) of the big brown bat, Eptesicus fuscus becomes sharper with increasing pulse repetition rate (PRR). The present study examines the role of GABAergic inhibition in improving duration selectivity of bat IC neurons with PRR by means of iontophoretic application of GABA as well as its antagonist, bicuculline. Duration selectivity of IC neurons is studied by plotting the duration tuning curves with the number of impulses per pulse against the pulse duration. Duration tuning curves of IC neurons are described as band-, short-, long- and all-pass in terms of filtering properties to sound duration. Bicuculline application produces more pronounced broadening of duration tuning curves at high than at low PRR. Conversely, GABA application produces more pronounced narrowing of duration tuning curves at low than at high PRR. In either case, sharpening of duration selectivity of IC neurons with increasing PRR is abolished during drug application. The duration tuning curves of IC neurons progressively broadens with recording depth. Broadening of duration tuning curves during bicuculline application is more pronounced for neurons at upper than at deep IC. This progressive decrease in duration selectivity with recording depth is discussed in relation to spatial distribution gradient of GABAA receptors in the IC. Possible biological significance of these findings relevant to bat echolocation is discussed.

Animals↗
PubMed2006

Duplex nested RT-PCR for detection of Nipah virus RNA from urine specimens of bats.

A method for duplex nested RT-PCR (nRT-PCR) with internal control (IC) for the detection of Nipah virus RNA is described. Incorporation of IC RNA distinguished false and true negative results. The extrinsic RNA was added directly to the PCR master mix and co-amplified with virus specific RNA in a duplex reaction to determine the presence of PCR inhibitor. Limit of detection was affected minimally when IC was added. Of 53 pooled urine samples collected from fruit bats (Pteropus lylei), 16 were validated by the presence of IC band on gel electrophoresis. Seven of these were also Nipah virus RNA positive. The remaining 37 samples were considered invalid. Twenty-two urine samples became valid after dilution of 1:5 and re-examined; two were Nipah virus RNA positive. These nine positive results were confirmed by sequencing of heminested PCR products. The result indicated that at least two different Nipah strains circulated in this bat species from Thailand. This method should be useful for surveillance for Nipah virus infection in animals in a country where a biosecurity level (BSL) 4 laboratory is not available. PCR inhibitors were present in a significant number of bat urine samples. The technique described in this study should improve reliability of surveillance statistics.

Animals↗
PubMed2006

Ovulation induction by antiestrogens in an Indian tropical vespertillionid bat, Scotophilus heathi.

The ovulation induction property of ICI 182,780 a pure antiestrogen and enclomiphene citrate (ENC) was carried out in Scotophilus heathi, an Indian tropical vespertillionid bat, during December to February i.e., preovulatory period. This bat ovulates two ova naturally and shows ovulatory asynchrony. The study showed that 100 ìg of ENC followed by 10 IU hCG resulted in significantly lower number of ovulation. Whereas, the pure antiestrogen ICI 182,780 at a dose of 100 ìg followed by 10 IU hCG resulted in ovulation induction (4.2 +/- 0.4), which is significantly different in comparison to other groups. This is possibly the first report of ovulation induction using this pure antiestrogen i.e., ICI 182,780 in any bat as well as in any animal model that exhibits temporary anovulation similar to polycystic ovary disease (PCOD). This antiestrogen may be useful to induce ovulation in PCOD patients.

Animals↗
PubMed2006

An epidemiological description of human-hazardous incidents caused by nonhematophagous bats in Brazil, 2002-2003.

The interaction of bats with humans and pets increases the risk for rabies transmission. The purpose of the present study was to describe and analyze the epidemiological picture of injuries and related incidents caused by bats, to characterize the profile of these incidents, and to define recommendations for improving the health care delivered to patients. Fifty-three records of human anti-rabies treatment of injuries or related incidents caused by bats in Campo Grande, MS, Brazil, in 2002 and 2003 were investigated. The frequency of fields with missing or incorrect information was very high in the record forms surveyed. The frequency of incidents was higher for male patients. Most patients were in the 20-29 years age range. Bites and indirect contacts accounted for 49 and 22%, respectively, of the types of exposure. The time lag between the incidents and the presentation of patients for anti-rabies assessment ranged from 0 to 3 days in most cases. As many as 49% of the patients did not complete the treatment prescribed. The results revealed the need for improving the current human rabies control program in order to reduce noncompliance rates and to decrease the occurrence of flaws in patients' records and in the provision of health care.

Adolescent↗
PubMed2004

Development of a hemi-nested RT-PCR method for the specific determination of European Bat Lyssavirus 1. Comparison with other rabies diagnostic methods.

A simplified hemi-nested reverse transcriptase polymerase chain reaction (hnRT-PCR) has been developed to determine specifically the European Bat Lyssavirus 1 (EBLV-1) nucleoprotein gene. The specificity of this method was determined by using the seven genotypes of lyssavirus by RT-PCR, Southern blot and sequence analysis. Compared to the rabies diagnostic methods, the hnRT-PCR showed a higher sensitivity for the detection of small amounts of EBLV-1 virus. In view of these results, we suggest this new hnRT-PCR should be performed for the epidemiological survey of bat colonies, also providing rapid detection and genotyping of EBLV-1 until now encountered in all naturally infected bats in France.

Amino Acid Sequence↗