Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “bats”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMedDate not supplied

Erythrocyte metabolism in two species of bats: common bent-wing bat (Miniopterus schreibersii) and red fruit bat (Pteropus scapulatus).

1. Metabolic intermediates, substrate utilization and enzyme activities were determined in the red blood cells of the common bent-wing bat and the red fruit bat. Standard haematological parameters and oxy-haemoglobin dissociation curves were also determined in both species. 2. The glycolytic rate as measured by lactate production was much higher for all substrates in the bent-wing bats. The activities of the glycolytic enzymes were also much higher in this species. 3. The standard haematological parameters were similar for the two species. The levels of 2,3-diphosphoglycerate (DPG) in the red cells of the fruit bat were nearly twice as high as those in the bent-wing bats. 4. The oxy-haemoglobin dissociation curve for the red fruit bat was located to the right of that for the bent-wing bat and both these curves were located to the right of that normally seen for human blood. 5. Both species of bat show blood characteristics well adapted to carrying the increased oxygen demands of flight.

Animals↗
PubMed1992

Stabilization of perceived echo amplitudes in echolocating bats. I. Echo detection and automatic gain control in the big brown bat, Eptesicus fuscus, and the fishing bat, Noctilio leporinus.

Previous research on echo detection in bats has suggested that the effective threshold is a function of the acoustic clutter in the experimental environment, as might be expected given the low ambient noise levels typical of such psychophysical research. This paper demonstrates that theory of signal detectability (TSD) methodology is applicable to bats and uses it to show that an important element of clutter limiting in Eptesicus fuscus and Noctilio leporinus is backward masking of phantom targets by the real echo from the loudspeakers used to generate them. This information suggests that a previous estimate of the magnitude of automatic gain control (AGC) is too high, due to variable backward masking inherent in the experimental method used. A re-examination of gain control using a masking-free method shows that it reduces auditory sensitivity by 6 to 7 dB per halving of target range, rather than 11 dB as previously thought.

Animals↗
PubMed1992

Geometry of blood-tissue exchange in bat flight muscle compared with bat hindlimb and rat soleus muscle.

We investigated the relationship between capillary-to-fiber geometry and muscle aerobic capacity by comparing the bat flight muscle (pectoralis muscle), i.e., an ultimate case of extreme O2 demand in a mammalian skeletal muscle, with bat hindlimb and rat soleus muscles. At a given sarcomere length (2.1 microns), fiber cross-sectional area was considerably smaller in bat muscles (pectoralis 318 +/- 10 microns 2, hindlimb 447 +/- 35 microns 2) than in rat soleus muscle (2,027 +/- 125 microns 2). Capillary number per fiber cross-sectional area was much greater in bat pectoralis (6,394 +/- 380/mm2) than in bat hindlimb and rat soleus muscle (2,865 +/- 238 and 1,301 +/- 129/mm2, respectively; all values normalized to 2.1-microns sarcomere length). At the same sarcomere length (2.1 microns), the degree of tortuosity and branching of capillaries were significantly greater in bat pectoralis than in bat hindlimb and rat soleus muscle. In bat flight muscle, capillary length per fiber volume was very high (9,025 +/- 342/mm2). It was 2.2- and 5.4-fold larger than in bat hindlimb and rat soleus, respectively. Mitochondria occupied 35.3 +/- 1.2, 16.5 +/- 1.3, and 6.1 +/- 0.9% of the muscle fiber volume in bat pectoralis, hindlimb, and rat soleus muscles, respectively. There was a strong correlation between capillary length (as well as capillary surface) per fiber volume and mitochondrial volume density in all muscles. Considering capillary supply and mitochondrial volume on an individual fiber basis, we found that 1) the number of capillaries around a fiber was linearly related to mitochondrial volume per micron length of fiber in the muscles but that 2) capillary surface per fiber surface, at given mitochondrial volume per micron length of fiber, was about twice as large in bat pectoralis as in rat soleus muscle, whereas in bat hindlimb it was intermediate between that in bat pectoralis and that in rat soleus muscle. This was due to the differences in fiber size (rat soleus greater than bat muscles) and capillary-to-fiber ratio (bat pectoralis greater than hindlimb) between the muscles. It is notable that in the bat, the substantially greater O2 transfer capacity of the flight muscle compared with hindlimb was achieved by increasing the size of the capillary-to-fiber interface, i.e., capillary-to-fiber surface, via an increase in capillary number rather than by substantially reducing fiber size.

Animals↗
PubMed1992

Ectoparasitic mites (Acari) of sympatric Brazilian free-tailed bats and big brown bats in Alabama.

Seven species of mites were recovered from 133 Brazilian free-tailed bats, Tadarida brasiliensis, and 94 big brown bats, Eptesicus fuscus, from February through November 1990 in colonies that shared roosting space in east-central Alabama. The macronyssid Chiroptonyssus robustipes (Ewing) was the most common mite on T. brasiliensis (964 mites, 87% of bats infested) and on E. fuscus (109 mites, 29% of bats infested). However, C. rubustipes normally is a specific parasite of T. brasiliensis. The macronyssids Steatonyssus ceratognathus (Ewing) and S. occidentalis (Ewing) were recovered from both species of bats in low numbers. S. ceratognathus is not a typical parasite of either species of bat, but S. occidentalis normally is specific to E. fuscus. Predictably, S. occidentalis was most frequently collected from E. fuscus (16 mites, 9% of bats infested), but two specimens were recovered from T. brasiliensis. Five specimens of the laelapid Androlaelaps casalis (Berlese) (a mite that is frequently associated with rodents) and one specimen of the myobiid mite Ewingana (Doreyana) longa (Ewing) (a specific ectoparasite of T. brasiliensis) were also recovered from T. brasiliensis. Singletons of the rosensteiniids Mydopholeus sp. and Nycteriglyphites pennsylvanicus Fain, Lukoschus & Whitaker were the only additional mites collected from E. fuscus; both of these mites have previously been collected from bats or their guano but are recorded here from Alabama for the first time. With respect to ectoparasite cross-infestations, E. fuscus appears to be at greater risk from sharing roots with T. brasiliensis. This is highlighted by the comparatively large numbers of C. robustipes that occurred on E. fuscus and the low numbers of S. occidentalis on T. brasiliensis. Although mites were the only arthropods recovered from bats in this study, a separate survey in 1991 revealed that the bat bug Cimex adjunctus Barber infested some other colonies of T. brasiliensis and E. fuscus in Alabama.

Alabama↗
PubMed1989

Reproduction of Angola free-tailed bats (Tadarida condylura) and little free-tailed bats (Tadarida pumila) in Malawi (Central Africa) and elsewhere in Africa.

Angola free-tailed bats and little free-tailed bats occur in diverse habitats throughout most of Africa south of the Sahara. This study investigated the reproductive strategies and related biology of these species in Malawi where they were sympatric, and analysed data from elsewhere in Africa to show how the strategies varied along a gradient of habitats from approximately 12 degrees N to 25 degrees S. Both the Angola free-tailed bat and the little free-tailed bat were normally monotocous. Angola free-tailed bats invariably had 2 births/year, and the interval between consecutive births decreased with increasing latitude. When the interval was shortest (approximately 90 days) a post-partum oestrus occurred. Little free-tailed bats differed by having a shorter gestation (approximately 60 days), and the ability to have up to 5 births/year with a postpartum oestrus after each birth. The extent to which this potential is achieved varies with latitude and rainfall, mainly so that lactation can coincide with peaks in the abundance of food. The interaction between rainfall and reproductive characteristics results in the two species having patterns of reproduction which are sometimes similar, but more often different. Competition between the species is unlikely to be affected by differences in their reproduction.

Africa↗
PubMed1988

Distribution of catecholamine fibers in the cochlear nucleus of horseshoe bats and mustache bats.

The glyoxylic-acid-induced fluorescence technique was applied to demonstrate patterns of catecholaminergic innervation within the auditory brainstem of echolocating bats and the house mouse. In the cochlear nucleus of the rufous horseshoe bat (Rhinolophus rouxi) and the mustache bat (Pteronotus parnellii), species-specific catecholaminergic innervation patterns are found that contrast with the relatively homogeneous innervation in the rodent. In both bats the subnuclei of the cochlear nucleus receive a differentially dense supply of catecholaminergic fibers, and within the subnuclei, the catecholamine innervation densities can be correlated with the tonotopic frequency representation. The areas devoted to the high-frequency echolocation calls are less densely innervated than those regions which are responsive to lower frequencies. Apart from this common scheme, there are noteworthy distinctions between the two bats which correlate with specialized cytoarchitectural features of the cochlear nucleus. The marginal cell group, located medially to the anteroventral cochlear nucleus of Pteronotus, receives the densest supply of catecholaminergic fibers of all auditory nuclei. This plexus is formed by a morphologically distinct population of catecholaminergic fibers.

Animals↗
PubMed1990

Audiovocal interactions during development? Vocalisation in deafened young horseshoe bats vs. audition in vocalisation-impaired bats.

Horseshoe bats (Rhinolophus rouxi) were deafened in their 3rd-5th postnatal week. Subsequently their vocalisations were monitored to evaluate the impact of audition on the development of echolocation pulses. Hearing impairment affected the echolocation pulses as follows: the frequency of the constant frequency (CF) component was altered by between +4 kHz and -14 kHz, and the dominance of the second harmonic of the pulses was neutralised by a relative increase in intensity of the first and third harmonics. A second experiment focused on possible influences of acoustical self-stimulation with echolocation pulses on the establishment of auditory fovea representation in the inferior colliculus (IC). Frequency control of echolocation pulses was disrupted by larynx denervation. Thereafter, the bats produced multiharmonic echolocation signals (4-11 harmonics) varying in frequency. IC tonotopy, however, as monitored by stereotaxic electrophysiology, showed the same developmental dynamics as seen in control specimens (Fig. 10). Both experiments indicate that throughout postnatal development echolocation pulses are under auditory feedback control, whereas maturation of the auditory fovea and shifts in its frequency tuning represent an innate process. The significance of this postnatal development might be the adjustment of the vocal motor system of each bat to the frequency of its 'personal' auditory fovea.

Animals↗
PubMed1977

Role of bats in the ecology of Paracoccidioides brasiliensis: the survival of Paracoccidioides brasiliensis in the intestinal tract of frugivorous bat, Artibeus lituratus.

The fruit-eating bat, Artibeus lituratus, was fed known quantities of viable yeast cells and mycelial particles of Paracoccidioides brasiliensis in an attempt to assess the role of this animal in the distribution of this agent in nature. Results of mycosal cultures of the stomach, upper intestine, lower intestine and rectum clearly showed that the fungal cells were unable to survive more than 8 hours in the digestive tract of the bat. The mycelial particles were more susceptible than the yeast and were killed before passing to the rectum. The fungus died rapidly in the voided fecal material. These findings indicate the improbability of isolating P. brasiliensis from the digestive tract of wild captured bats and show that A. lituratus probably plays no role in the distribution of this fungus in nature.

Animals↗
PubMed1992

Stabilization of perceived echo amplitudes in echolocating bats. II. The acoustic behavior of the big brown bat, Eptesicus fuscus, when tracking moving prey.

Big brown bats, Eptesicus fuscus, can be trained to use echolocation to track a small microphone with a food reward attached when it is moved rapidly toward them. This situation mimics prey interception in the wild while allowing very precise recording of the sonar pulses emitted during tracking behavior. The results show that E. fuscus intensity compensates, reducing emitted intensity by 6 dB per halving of target range so that the intensity incident upon the target is constant and echo intensity increases by 6 dB per halving of range. This increase in echo intensity is effectively canceled by the reduction in auditory sensitivity due to automatic gain control (AGC) of 6 to 7 dB per halving of range. Intensity compensation behavior and AGC therefore form a dual-component, symmetrical system that stabilizes perceived echo amplitudes during target approach. The same system is present in the fishing bat, Noctilio leporinus, suggesting that it may be widespread in echolocating bats. Correlation analysis shows that, despite large changes in the duration of the pulses emitted by E. fuscus during an approach, the pulse frequency structure is such that the spatial image of the target perceived along the range axis is highly stable. Pulse duration is not reduced in the manner theoretically necessary to eliminate potential echo distortion effects due to AGC, but is reduced in such a way that this distortion is insignificant. During the terminal buzz, a high degree of temporal overlap (relative to pulse duration) occurs between emitted pulse and returning echo.

Animals↗
PubMed1990

Neural control of vocalization in bats: mapping of brainstem areas with electrical microstimulation eliciting species-specific echolocation calls in the rufous horseshoe bat.

1. The functional role of brainstem structures in the emission of echolocation calls was investigated in the rufous horseshoe bat. Rhinolophus rouxi, with electrical low-current microstimulation procedures. 2. Vocalizations without temporal and/or spectral distortions could be consistently elicited at low threshold currents (typically below 10 microA) within three clearly circumscribed brainstem areas, namely, the deep layers and ventral parts of the intermediate layers of the superior colliculus (SC), the deep mesencephalic nucleus (NMP) in the dorsal and lateral midbrain reticular formation and in a distinct area medial to the rostral parts of the dorsal nucleus of the lateral lemniscus. The mean latencies in the three vocal areas between the start of the electrical stimulus and the elicited vocalizations were 47 msec, 38 msec and 31 msec, respectively. 3. In pontine regions and the cuneiform nucleus adjacent to these three vocal areas, thresholds for eliciting vocalizations were also low, but the vocalizations showed temporal and/or spectral distortions and were often accompanied or followed by arousal of the animal. 4. Stimulus intensity systematically influenced vocalization parameters at only a few brain sites. In the caudo-ventral portions of the deep superior colliculus the sound pressure level of the vocalizations systematically increased with stimulus intensity. Bursts of multiple vocalizations were induced at locations ventral to the rostral parts of the cuneiform nucleus. No stimulus-intensity dependent frequency changes of the emitted vocalizations were observed. 5. The respiratory cycle was synchronized to the electrical stimuli in all regions where vocalizations could be elicited as well as in more ventrally and medially adjacent areas not yielding vocalizations on stimulation. 6. The possible functional involvement of the "vocal" structures in the audio-vocal feedback system of the Dopplercompensating horseshoe bat is discussed.

Animals↗
PubMed1986

Control of echolocation pulses by neurons of the nucleus ambiguus in the rufous horseshoe bat, Rhinolophus rouxi. I. Single unit recordings in the ventral motor nucleus of the laryngeal nerves in spontaneously vocalizing bats.

The vocal motor control of the larynx was studied with single unit recordings from the efferent motor nucleus (nucleus ambiguus) in the CF-FM-bat Rhinolophus rouxi, spontaneously emitting echolocation sounds. The experiments were performed in a stereotaxic apparatus that allowed differentiation of activities in the recorded nucleus depending on the electrode position (Fig. 1). Echolocation calls and respiration activity were monitored simultaneously, thus it was possible to compare the time course of the motor control activity during respiration with and without concurrent vocalization. Unit discharges were classified as laryngeal motoneuron activity according to their correlation with the time course (onset and end) of echolocation calls and their discharge rate as: Pre-off-tonic, pre-off-phasic, off-pauser, off-tonic, on-chopper, on-tonic, prior-tonic and inhibitory (Fig. 4). The on-chopper and on-tonic discharge patterns were assigned to the motor activity of the lateral cricoarytenoid muscle and the off-pauser and off-tonic discharge patterns to the motor activity of the posterior cricoarytenoid muscle controlling the time course of vocal pulses. Motoneuron activities recorded under the condition of systematically shifted frequencies in the emitted echolocation calls were investigated in Doppler-shift compensating bats responding to electronically simulated echoes. Of all neurons classified as motor control, only units of the pre-off-tonic discharge type (cricothyroid muscle) changed their activity with frequency shifts in the vocalized pulses; they showed a positive linear correlation with the emitted sound frequency (Fig. 6). In addition, single unit activities in strict synchronization to vocalization were recorded, that by their low discharge rate were not valid as motor control, and were considered to represent activities of interneurons or internuclear neurons connecting the nucleus ambiguus with other vocalization- and respiration-centers (Fig. 3c). Electric lesions in the brain stem and iontophoretically applied horseradish peroxidase (HRP) served as references for localization and morphological identification of the recording sites in cell stained brain slices.

Animals↗
PubMedDate not supplied

[Effect of destruction of the auditory centers of the brain on the range of echolocation by bats Rhinolophus ferrum-equinum (the large horseshoe-nose bat)].

Effect of the auditory cortex, internal geniculate bodies and inferior colliculus removal on echo-ranging detection of immovable wire obstacle by bats has been studied in the behavioural procedure. It is shown that destruction of the auditory cortex results in an irreversible decrease (to 74.6% of control values) in limiting detection range of obstacle by animals. Extensive destructions of internal geniculate bodies decrease limiting detection range only in the first postoperative days. In the case of the inferior colliculi + removal the limiting detection range irreversibly decreases to values equaling 38.5% of control ones. A suggestion that the obtained effects are a consequence of the auditory system sensitivity deterioration in bats is substantiated.

Animals↗
PubMed1979

Partial purification and characterisation of bat liver ribonuclease. Hydrolysis of purine and pyrimidine polynucleotides by bat liver RNase.

A ribonuclease has been extracted from bat liver and purified. From polyacrylamide gel electrophoresis, it was found that there is only one molecular weight unit in this enzyme and this has a molecular weight of about 28,000. This enzyme was found to hydrolyse both purine and pyrimidine polynucleotides (e.g. polyadenylic acid and polycytidylic acid respectively). Hydrolysis of polyadenylic acid was found to be faster than that of polycytidylic acid.

Animals↗
PubMed1985

Retinofugal projections of the big brown bat, Eptesicus fuscus and the neotropical fruit bat, Artibeus jamaicensis.

Retinal connections were studied in Eptesicus fuscus and Artibeus jamaicensis using anterograde axonal degeneration and autoradiographic techniques following unilateral enucleations and uniocular injections of radioactive amino acids. Although each retina projected bilaterally to the brainstem, the number of silver grains in the emulsion of autoradiographs indicated that nearly all fibers in the optic nerve entered the contralateral optic tract. Ipsilaterally, a major portion of the projection ended in the suprachiasmatic nucleus; caudal to the suprachiasmatic nucleus, the amount of label was so small that individual silver grains were counted to determine the location and quantity of label in other ipsilateral nuclei. In both species the retinal projection terminated bilaterally in the suprachiasmatic, dorsal lateral geniculate, ventral lateral geniculate, and pretectal olivary nuclei and contralaterally in the posterior pretectal nucleus, superficial gray layers of the superior colliculus, and nuclei of the accessory optic system. In Eptesicus the projection to the nucleus of the optic tract ended contralaterally, and in Artibeus it ended in this nucleus bilaterally. The results of this study revealed a basic theme in the optic projection of the two ecologically different microchiropterans. The results differed, however, in that the projection was larger and visually related nuclei were better developed in Artibeus. Such variations are presumed to relate to eye size and the relative use of vision by the two chiropterans.

Animals↗