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At least 73 records · Page 4Linked to original sources
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↗
PubMed1998

Co-expression of cytokeratins and vimentin by highly invasive trophoblast in the white-winged vampire bat, Diaemus youngi, and the black mastiff bat, Molossus ater, with observations on intermediate filament proteins in the decidua and intraplacental trophoblast.

Histological and immunocytochemical studies of gravid reproductive tracts obtained from the white-winged vampire bat (Diaemus youngi) and the black mastiff bat (Molossus ater) have established that both species develop unusually invasive trophoblast. This is released by the developing discoidal haemochorial placenta, expresses both cytokeratins and vimentin, and invades the myometrium and adjacent tissues (including the ovaries) via interstitial migration within the walls of maternal blood vessels. Hence, this trophoblast is noteworthy for the extent to which it undergoes an epithelial-mesenchymal transformation. In Molossus, it originates from the cytotrophoblastic shell running along the base of the placenta, is mononuclear, and preferentially invades maternal arterial vessels serving the discoidal placenta. This trophoblast may have a role in dilatation of these vessels when the discoidal placenta becomes functional. In Diaemus, the highly invasive trophoblast appears to originate instead from a layer of syncytiotrophoblast on the periphery of the placenta is multinucleated, and vigorously invades both arterial and venous vessels. During late pregnancy, it becomes extensively branched and sends attenuated processes around many of the myometrial smooth muscle fibres. In view of its distribution, this trophoblast could have important influences upon myometrial contractility and the function of blood vessels serving the gravid tract. Other aspects of intermediate filament expression in the uteri and placentae of these bats are also noteworthy. Many of the decidual giant cells in Molossus co-express cytokeratins and vimentin, while the syncytiotrophoblast lining the placental labyrinth in Diaemus late in pregnancy expresses little cytokeratin.

Animals↗
PubMed2005

Bat flies (Diptera: Streblidae, Nycteribiidae) parasitic on bats (Mammalia: Chiroptera) at Parque Estadual da Cantareira, São Paulo, Brazil: parasitism rates and host-parasite associations.

A total of 443 bat flies belonging to the families Nycteribiidae and Strelidae, were collected on 22 species of bats (Molossidae, Phyllostomidae, and Vespertilionidae) from Parque Estadual da Cantareira (São Paulo, Brazil), between January, 2000 and January, 2001. Eighteen new occurrences of bat flies were recorded on Anoura geoffroyi (Anastrebla caudiferae), Glossophaga soricina (A. caudiferae), Sturnira lilium (Trichobius phyllostomae, T. furmani, and Paraeuctenodes similis), Artibeus lituratus (A. caudiferae), A. fimbriatus (Megistopoda proxima), A. obscurus (Metelasmus pseudopterus), Myotis nigricans (M. proxima, M. aranea, Paratrichobius longicrus), M. ruber (Anatrichobius passosi, Joblingia sp.), M. levis (A. passosi), M. albescens (A. passosi, Basilia andersoni), and Histiotus velatus (M. aranea). Seven new occurrences were recorded for the state of São Paulo, increasing the range for T. tiptoni, T. furmani, M. proxima, Aspidoptera falcata, A. caudiferae, A. modestini and B. andersoni. The relationships between parasitism and host sex, reproductive stage, age hyperparasitism by fungi are discussed.

Age Factors↗
PubMed1999

Eimeria from bats of Bolivia: two new species from vespertilionid bats.

Between 1985 and 1987, fecal samples were collected from 71 bats representing 14 species (Desmodontidae, Molossidae, Noctilionidae, Phyllostomidae, Vespertilionidae) from 8 localities in 3 states (Beni, Pando, Santa Cruz) in Bolivia, South America. Of these, 2 black myotid bats (Vespertilionidae), Myotis nigricans, and 1 tent-making bat (Phyllostomidae), Uroderma magnirostrum, had oocysts in their feces that represent undescribed species of Eimeria. The new species from M. nigricans (2/4, 50%) has sporulated oocysts that are subspheroidal, 18.9 x 16.9 (17-23 x 14-20) microm, without a micropyle; oocyst residuum of 6-8 spheroidal globules and 1 highly refractile polar granule are present. The oocyst wall has 2 layers (approximately 1.3 microm thick), with a rough outer layer. Ovoidal sporocysts are 10.1 x 7.4 (7-14 x 5-10) microm, with a Stieda body, substieda body, and a sporocyst residuum. The new eimerian species from U. magnirostrum (1/2, 50%) has sporulated oocysts that are subspheroidal to ellipsoidal, 23.8 x 20.8 (20-26 x 19-24) microm, without micropyle or oocyst residuum, but 1-3 polar granules are present. The oocyst wall has 2 layers (approximately 1.5 microm thick), with a rough, mammilated outer layer. Ovoidal sporocysts are 11.6 x 8.6 (10-12 x 7-10) microm, with a Stieda body, substieda body and a sporocyst residuum.

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↗
PubMed1999

Fluorescent BAT-25 and BAT-26 analysis of T cell prolymphocytic leukaemia.

T cell prolymphocytic leukaemia (T-PLL) is a chronic mature T cell malignancy with many random cytogenetic abnormalities. These imply that maintenance of genomic integrity is impaired. This is supported by the recent finding that the ataxia telangiectasia gene, ATM, which contributes to maintaining genomic integrity, is frequently mutated in this disease. To evaluate in T-PLL the role of other genes with comparable function, a fluorescence-based semi-automated assay was developed for BAT-25 and BAT-26. These markers contain sequences that are particularly unstable in cells with DNA mismatch repair defects. Application of the assay to 20 T-PLL cases found no evidence for such defects.

DNA Repair↗
PubMed1998

Non-rabies Lyssavirus human encephalitis from fruit bats: Australian bat Lyssavirus (pteropid Lyssavirus) infection.

A 39-year-old woman died of encephalitis a few weeks after being scratched by fruit bats. Autopsy disclosed meningoencephalomyelitis, and revealed neuronal intracytoplasmic inclusions which had similarities to Negri bodies of rabies. Laboratory investigations detected a Lyssavirus type previously identified only in fruit bats. This appears to be the first human case of encephalitis due to this Lyssavirus type.

Adult↗
PubMed2004

Copper-associated hepatopathy in a Mexican fruit bat (Artibeus jamaicensis) and establishment of a reference range for hepatic copper in bats.

Copper toxicity has been described in numerous domestic species. The characteristic lesions include hemoglobinuric nephrosis and piecemeal hepatic necrosis with bile ductular hyperplasia and portal fibrosis. Certain species, such as sheep, are prone to toxicity when exposed to copper in feed, whereas an inherent genetic defect of copper storage is present in some breeds of dogs (Bedlington Terriers, West Highland White Terriers, Doberman Pinschers). In nondomestic species, reference ranges have not been established for copper in internal organs, so the establishment of copper toxicity as a diagnosis is difficult. A case of copper toxicity in a captive Mexican fruit bat is presented. Hepatic copper levels in 16 additional bats, of at least 3 different species, were measured. To the authors' knowledge, this is the first reported case of copper toxicity in a chiropteran.

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↗
PubMed1981

Histochemical observations on the female reproductive tract of bats. IV. Mucopolysaccharides in the uterus of three species of bats.

The three species of bats studied show glycogen, neutral, sialo- and sulfomucins in the cells of the uterine epithelium and glands. Elaboration of these mucins occurs during anestrus in Pteropus giganteus and during proestrus in Taphozous longimanus. In Megaderma lyra lyra only glycogen is observed during anestrus and proestrus. Neutral, and sialomucins in addition to glycogen are observed during estrus. The concentration of these mucins increases progressively and is maximum at the time of implantation, decreasing thereafter in all the three species of bats. The elaboration and increase of mucins is probably under the influence of hormones of the ipsilateral ovary.

Animals↗
PubMed1980

Histochemical observations on the female reproductive tract of bats. III. Mucosubstances in the Fallopian tube of three species of bats.

The epithelium of the three species of bats studied shows the presence of ciliated and nonciliated cells both in the ovarian and uterine segments of the Fallopian tube of the functional uterine horn. The cytoplasm of these two cells types shows small amount of glycogen during anestrus, the amount increasing during proestrus and estrus. At estrus, the nonciliated cells show the presence of neutral and sialomucins in addition to glycogen in Pteropus giganteus giganteus and Megaderma lyra lyra. The concentration of these mucins was found to decline during pregnancy and parturition. In Taphozous longimanus, the mucins which are located in cytoplasmic projections or domes of the nonciliated cells show the presence of neutral, sialomucins, sulfomucins and glycogen. These mucins which are first seen in the proestrus period increase during estrus. However, during pregnancy, these domes regress concomitant with decline in the mucin content. Glycogen content of the ciliated cells increases during estrus and decreases during pregnancy. Since in all the three species of bats the mucin content is at its maximum at oestrus and shows a decline during pregnancy, it appears that its elaboration and increase is under the influence of estrogen, instead progesterone blocks its generation and brings about its release.

Animals↗
PubMed1998

Arctiid moths and bat echolocation: broad-band clicks interfere with neural responses to auditory stimuli in the nuclei of the lateral lemniscus of the big brown bat.

Clicks emitted by arctiid moths interfere with the ranging ability of echolocating bats. To identify possible neural correlates of this interference, we recorded responses of single units in the nuclei of the lateral lemniscus to combinations of a broad-band click and a test signal (pure tones or frequency-modulated sweeps). In 77% of 87 units tested, clicks interfered with neural responses to the test stimuli. The interference fell into two categories: latency ambiguity and suppression. Units showing latency ambiguity responded to both the click and the test signal. However, when the click occurred within a window of approximately 3 ms before the onset of the test signal, the latency of the response to the test signal was affected. Units that were suppressed did not respond to clicks. Nevertheless, when a click was presented immediately before or simultaneously with a test signal, the response to the test signal was eliminated. Both types of units were found throughout the lateral lemniscus except for the columnar division of the ventral nucleus, where all units tested exhibited latency ambiguity. There is a close match between the single unit data and previous studies of range difference discrimination in the presence of clicks.

Acoustic Stimulation↗
PubMed2006

Natural and experimental infection of sheep with European bat lyssavirus type-1 of Danish bat origin.

In 1998 and 2002, European bat lyssavirus type-1 (EBLV-1) was demonstrated in brain tissue of five Danish sheep suffering from neurological disorders. Four of the five sheep also had encephalic listeriosis. The animals originated from four flocks on pastures within a limited area of western Jutland. In a serological investigation in two of the herds, from which three of the diseased animals originated, EBLV-1 neutralizing antibodies were detected in only one of 69 sheep. In follow-up surveys, 2110 sheep sera collected at Danish slaughterhouses during 2000 were all negative for EBLV-1-antibodies, and EBLV-1 was not demonstrated in 87 ruminants displaying neurological symptoms. To investigate the pathogenic effects of EBLV-1, four sheep were inoculated intralabially with either brain material from one of the naturally infected sheep or virus isolated from the same sheep. These animals developed EBLV-1 neutralizing antibodies at 5-9 weeks post-inoculation but did not exhibit neurological signs during a 33-week observation period. It was speculated that the immune response prevented viral dissemination to the brain, resulting in an abortive peripheral infection. It was concluded that EBLV-1 can infect sheep under natural conditions as an incidental event.

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↗