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Monoclonal antibody studies of rabies in insectivorous bats of the United States.

Isolates of rabies virus from terrestrial animals in six geographically separate rabies enzootic areas of the United States were examined with a panel of monoclonal antibodies to the viral N protein. Characteristic differences in immunofluorescence reactions permitted the formation of five antigenically distinct reaction groups from the 328 isolates tested. Distinctive reaction patterns were also identified for isolates from four species of bats. These observations were used to determine the role of infected bats in 19 cases of rabies that had occurred in terrestrial animals living in areas free of enzootic rabies in terrestrial wildlife and to estimate the contribution of infected bats to rabies in cats and foxes in the United States. The findings suggest that monoclonal antibodies can be used to study the prevalence, distribution, and transmission of rabies among wildlife species.

Animals↗
PubMed1991

Length and sequence variation in evening bat D-loop mtDNA.

Length variation in D-loop mitochondrial DNA was observed after amplification with the polymerase chain reaction (PCR) in 28% of 195 evening bats, Nycticeius humeralis, from seven colonies. Nucleotide sequences of PCR products show that this heteroplasmy is characterized by an 81-bp region which is tandemly repeated five to eight times. Southern blots using PCR products as probes on HaeIII genomic digests confirm the presence of heteroplasmy. Furthermore, densitometry of electrophoresed PCR products from 109 mother-offspring pairs indicate that heteroplasmy is stably transmitted from mother to offspring with one exception: a heteroplasmic offspring had a homoplastic mother and sib. Nucleotide sequences from this family reveal that a repeat duplication and deletion occurred. The observed mutation rate per generation, mu, for length polymorphism is comparable to an independent estimate, mu = 10(-2), based on hierarchical diversity statistics. With the exception of the repeat nearest the proline tRNA gene, sequence similarities between repeats within bats are consistent with a model of concerted evolution due to unidirectional replication slippage. Selection is inferred to act on the first repeat because in comparison to other repeats it has the least sequence divergence among bats, the fewest transversions, and the lowest minimum free energy associated with folding.

Animals↗
PubMed1997

Evolution of repeated sequence arrays in the D-loop region of bat mitochondrial DNA.

Analysis of mitochondrial DNA control region sequences from 41 species of bats representing 11 families revealed that repeated sequence arrays near the tRNA-Pro gene are present in all vespertilionine bats. Across 18 species tandem repeats varied in size from 78 to 85 bp and contained two to nine repeats. Heteroplasmy ranged from 15% to 63%. Fewer repeats among heteroplasmic than homoplasmic individuals in a species with up to nine repeats indicates selection may act against long arrays. A lower limit of two repeats and more repeats among heteroplasmic than homoplasmic individuals in two species with few repeats suggests length mutations are biased. Significant regressions of heteroplasmy, theta and pi, on repeat number further suggest that repeat duplication rate increases with repeat number. Comparison of vespertilionine bat consensus repeats to mammal control region sequences revealed that tandem repeats of similar size, sequence and number also occur in shrews, cats and bighorn sheep. The presence of two conserved protein-binding sequences in all repeat units indicates that convergent evolution has occurred by duplication of functional units. We speculate that D-loop region tandem repeats may provide signal redundancy and a primitive repair mechanism in the event of somatic mutations to these binding sites.

Animals↗
PubMed1991

Mammalian aging, metabolism, and ecology: evidence from the bats and marsupials.

This study compared trends in body size, life span, metabolic rate, and ecology of bats and marsupials with those from mammals generally, using a 580 species data base. The linear logarithmic relationship between mammalian body mass and maximum longevity, deleting bats and marsupials, is used as a standard against which to measure life spans of particular mammal groups. Bats have maximum life spans a minimum of 3 times those of nonflying eutherians--a trend resulting from neither low basal metabolic rate, the ability to enter torpor, nor large relative brain size. Marsupials live about 80% as long as nonflying eutherians despite averaging lower basal metabolic rates; similarly, there is no effect of heterothermy or relative brain size. These results directly conflict with predictions of both "rate of living" and brain-size mediated theories of aging. However, they are consistent with an evolutionary theory that posits exceptionally long life spans among mammals with reduced environmental vulnerability.

Aging↗
PubMed1984

Betaine delays the onset of neurological impairment in nitrous oxide-induced vitamin B-12 deficiency in fruit bats.

The mechanism whereby vitamin B-12 deficiency leads to neurological changes in humans is still uncertain. Nitrous oxide (N2O), which inactivates vitamin B-12 in vivo, results in neurological impairment leading to ataxia and death in the fruit bat Rousettus . These changes were prevented by the injection of the vitamin. The effect of dietary betaine (a catalytic product of choline) or methionine supplementation was studied in bats exposed to N2O. Supplementation with betaine resulted in less weight loss and delayed onset of neurological impairment when compared with unsupplemented animals. Supplementation with methionine at similar concentrations (600 mg/kg fruit and 2 g/kg fruit) was more effective in preventing weight loss and delaying the onset of neurological impairment than the corresponding levels of betaine. These results suggest that dietary betaine was effective in increasing that part of methionine synthesis that is not dependent on vitamin B-12 in N2O-exposed bats with impairment of the vitamin B-12-dependent methionine synthase reaction.

Animals↗
PubMed1994

An endogenous circannual rhythm of reproduction in a tropical bat, Anoura geoffroyi, is not entrained by photoperiod.

Most species of mammals live in the tropics, and many breed seasonally, but little is known about the regulation of their seasonal cycles. Males of a tropical bat, Anoura geoffroyi (Order Chiroptera, Family Phyllostomidae), from 10 degrees latitude in Trinidad, were studied to test the role of photoperiod in regulating seasonal reproduction in the deep tropics. Groups of males were subjected to five treatments: 1) constant photoperiod; 2) a 12-mo cycle of civil twilight photoperiods mimicking those occurring at 10 degrees latitude; 3) civil twilight photoperiods of 10 degrees latitude, but accelerated to a 9-mo cycle; 4) civil twilight photoperiods characteristic of 30 degrees latitude, but accelerated to a 9-mo cycle; and 5) constant photoperiod, but with the timing of dark onset varied to match the timing of darkness at 10 degrees latitude, and accelerated to a 9-mo cycle. In all treatments, the first cycle of testis growth and regression matched that expected in the wild population, as reported previously for some of these groups. Subsequently, the testis cycle of bats in constant conditions free-ran for 20 mo with a peak-to-peak period of 7.3 +/- 0.3 mo. Period lengths in the four nonconstant groups, 7.2-7.7 mo, were not significantly different from that under constant conditions. Bats failed to entrain to any photoperiod cycle, including those mimicking changes at 10 degrees or 30 degrees latitude. They also failed to entrain to the cycle in which day length was held constant while time of sunset was varied, as occurs at the equator.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2000

Auditory responses from the frontal cortex in the mustached bat, Pteronotus parnellii.

Response properties of neurons in an auditory field in the frontal cortex of the mustached bat, Pteronotus parnellii, have not been studied before. We recorded neural responses to constant frequency (CF) stimuli from the frontal auditory field in awake animals. The majority (75%) of neurons in this area responded well and often exhibited low thresholds to CF stimuli. Most CF-responsive neurons exhibited sharp tuning with values of > 180 for Q10db, a quality factor expressing the sharpness of tuning at 10dB above threshold. Neurons at 13 recording sites exhibited combination sensitivity in that their responses were facilitated by presenting combinations of either CF1/CF2 and/or CF1/CF3 components of the mustached bat's echolocation signal. Unlike the typical on-responses to a 30 ms tone, observed in the mustached bat's auditory cortex and at subcortical levels, many frontal auditory neurons exhibited loosely time locked firing patterns that lasted for > 100 ms.

Animals↗
PubMed2000

Auditory responses from the frontal cortex in the short-tailed fruit bat Carollia perspicillata.

Based on neuroanatomical findings it was hypothesized that an area in the bat frontal cortex is part of a sensorimotor feedback loop and probably important to goal-directed behaviors guided by auditory information. The present report describes the basic stimulus preferences and response properties of neurons from this area in the short-tailed fruit bat Carollia perspicillata. Responses to acoustic stimuli mimicking biosonar pulse-echo (i.e. FM-FM) combinations were found to be facilitated throughout but only rarely exhibited tuning to pulse-echo delay. As opposed to the often sharply delay-tuned FM-FM neurons in the species' auditory cortex, frontal cortical FM-FM neurons seem to be suited for indicating the presence of an insonified object irrespective of its distance and hence are likely to function as novelty detectors and to trigger changes in the bats' orientation behavior.

Acoustic Stimulation↗
PubMed1992

Microsurgical forearm "cricket bat-transformer" phalloplasty.

Presently, the donor flap of choice for microsurgical phallic reconstruction is the radial forearm flap. The success of several different design modifications confirms the reliability of the radial and ulnar forearm flaps. Farrow et al. described their experience with the "cricket bat" concept in 1980. To the previous "cricket bat" design, we now wish to add modifications. These modifications utilize longitudinal and transverse rotations of the linear forearm tissues to create a phallus--much like the transformation of a toy robot into a truck. Deepithelialized flaps and a full-thickness skin graft coronoplasty complete glans reconstruction. The "cricket bat-transformer" flap appears to produce the most predictable results in subtotal phallic reconstructions and phallic constructions in the pediatric and transgender patient groups.

Adult↗
PubMed2006

Sound azimuth selectivity of inferior collicular neurons in juvenile bats, Myotis chinensis.

The directional selectivity of auditory neurons is one of the essential response properties that underlie sound localization, an important task performed by the mammalian auditory system. Here we evaluated the sound azimuth selectivity of inferior collicular neurons in juvenile bats, Myotis chinensis, at the age of 15 days under free-field stimulation conditions. Compared with those in adult bats, neurons in juvenile bats were broadly tuned to sound azimuth angles as indicated by both the type and width of the azimuth selectivity curves. Their best azimuth was distributed over a wide range and, moreover, the adult-like relationship between the best azimuth and the best frequency of these neurons was not developed. These data indicate that the directional selectivity of inferior collicular neurons, like other response properties examined previously, undergoes considerable change during postnatal maturation.

Acoustic Stimulation↗
PubMed2006

Brain structures of echolocating and nonecholocating bats, derived in vivo from magnetic resonance images.

Magnetic resonance images of the brain of five species of wild bats, including three species of Microchiroptera, one species of echolocating Megachiroptera and one species of nonecholocating Megachiroptera, were obtained in vivo. The relative volumes of the inferior colliculus and the superior colliculus to the brainstem were derived from the magnetic resonance images and compared among different species. In general, the relative size of the inferior colliculus was much larger in Microchiropterans than in Megachiropterans, and in echolocating Megachiropterans than in nonecholocating Megachiropterans. The relative size of the superior colliculus was similar in these two suborders. Agreeing with the previous results and consistent with the current hypothesis that Megachiropterans originated from Microchiropterans, the results suggest that the inferior colliculus of Megachiropterans tends to degenerate during the process of evolution, as these fruit bats use more vision and smell than hearing when they forage. The results also demonstrate that magnetic resonance imaging can be used to study the neuroanatomy of wild bats noninvasively.

Animals↗
PubMed2005

Roosts as information centres: social learning of food preferences in bats.

The short-tailed fruit bat, Carollia perspicillata, lives in groups in tree hollows and caves. To investigate whether these roosts might serve as information centres, we tested whether individuals' preferences for novel foods could be enhanced through social learning at the roost. We also determined whether socially learned preferences for novel foods were reversed through interaction with other roost mates by simulating changes in available food resources such as those associated with variations in timing of fruit production in different plant species. Bats exhibited socially induced preferences that were readily reversible. We suggest that for frugivorous bats, roosts can serve as centres for information exchange about novel and familiar, ephemeral foods without requiring conspecific recruitment to these resources.

Animals↗
PubMed1997

Can skull morphology be used to predict ecological relationships between bat species? A test using two cryptic species of pipistrelle.

Can ecological relationships between bat species be predicted largely on the basis of morphology? This question was addressed by investigating skull morphology of two cryptic species of the pipistrelle bat. Since 45 Pipistrellus pipistrellus apparently eats larger prey than 55 P. pipistrellus, we predicted that it would have a larger overall skull size, a larger dentary apparatus, and a larger gape. To test these predictions, variables were measured from skulls of the two cryptic species, and comparisons made between them. In accordance with our predictions, overall skull size was larger in 45 P. pipistrellus than in 55 P. pipistrellus, and 45 P. pipistrellus had a longer lower jaw and the distance between the jaws at maximum gape was larger. In addition, 45 P. pipistrellus had longer upper canines, which may allow it to pierce harder prey items than 55 P. pipistrellus. Only some aspects of dietary differences between the two cryptic species could be explained by differences in skull morphology, and we suggest that empirical data, at least on diet and habitat use, are also required to explain mechanisms of resource partitioning among species in bat communities.

Analysis of Variance↗
PubMed1998

Bat defence in lekking ghost swifts (Hepialus humuli), a moth without ultrasonic hearing.

The Hepialidae represents an early branch of the Lepidoptera, whose members lack the ultrasonic hearing and other obvious predator defence systems present in other extant moths. I observed lekking male ghost swifts, Hepialus humuli, being exploited by northern bats, Eptesicus nilssonii, over a hayfield in southern Sweden. Because the moth's display flight was restricted to a brief (30 min) period at dusk, they avoided most predators temporally but were exposed to early emerging aerial-hawking bats. Against these, they apparently employed 'acoustic crypsis', achieved by flying close (< 0.5 m) to the vegetation, thereby hiding from the bats among clutter (echoes returning from the background). Nevertheless, the predation risk for the displaying moth males was very high (20% per night), mainly because they sometimes left the safety of the vegetation. The lack of 'advanced' predator defence mechanisms in H. humuli requires alternative defence strategies, which, however, restrict the behavioural repertoire and still carry a high predation risk.

Animals↗
PubMed2001

The energetic grooming costs imposed by a parasitic mite (Spinturnix myoti) upon its bat host (Myotis myotis).

Parasites often exert severe negative effects upon their host's fitness. Natural selection has therefore prompted the evolution of anti-parasite mechanisms such as grooming. Grooming is efficient at reducing parasitic loads in both birds and mammals, but the energetic costs it entails have not been properly quantified. We measured both the energetic metabolism and behaviour of greater mouse-eared bats submitted to three different parasite loads (no, 20 and 40 mites) during whole daily cycles. Mites greatly affected their time and energy budgets. They caused increased grooming activity, reduced the overall time devoted to resting and provoked a dramatic shortening of resting bout duration. Correspondingly, the bats' overall metabolism (oxygen consumption) increased drastically with parasite intensity and, during the course of experiments, the bats lost more weight when infested with 40 rather than 20 or no parasites. The short-term energetic constraints induced by anti-parasite grooming are probably associated with long-term detrimental effects such as a decrease in survival and overall reproductive value.

Animals↗
PubMed2003

Information transfer about roosts in female Bechstein's bats: an experimental field study.

Information transfer among group members is believed to play an important part in the evolution of coloniality in both birds and bats. Although information transfer has received much scientific interest, field studies using experiments to test the underlying hypotheses are rare. We used a field experiment to test if communally breeding female Bechstein's bats (Myotis bechsteinii) exchange information regarding novel roosts. We supplied a wild colony, comprising 17 adult females of known relatedness, with pairs of suitable and unsuitable roosts and monitored the arrival of individuals marked with transponders (PIT-tags) over 2 years. As expected with information transfer, significantly more naive females were recruited towards suitable than towards unsuitable roosts. We conclude that information transfer about roosts has two functions: (i) it generates communal knowledge of a large set of roosts; and (ii) it aids avoidance of colony fission during roost switching. Both functions seem important in Bechstein's bats, in which colonies depend on many day roosts and where colony members live together for many years.

Animal Communication↗
PubMed2004

Dynamics of jamming avoidance in echolocating bats.

Animals using active sensing systems such as echolocation or electrolocation may experience interference from the signals of neighbouring conspecifics, which can be offset by a jamming avoidance response (JAR). Here, we report JAR in one echolocating bat (Tadarida teniotis: Molossidae) but not in another (Taphozous perforatus: Emballonuridae) when both flew and foraged with conspecifics. In T. teniotis, JAR consisted of shifts in the dominant frequencies of echolocation calls, enhancing differences among individuals. Larger spectral overlap of signals elicited stronger JAR. Tadarida teniotis showed two types of JAR: (i) for distant conspecifics: a symmetric JAR, with lower- and higher-frequency bats shifting their frequencies downwards and upwards, respectively, on average by the same amount; and (ii) for closer conspecifics: an asymmetric JAR, with only the upper-frequency bat shifting its frequency upwards. In comparison, 'wave-type' weakly electric fishes also shift frequencies of discharges in a JAR, but unlike T. teniotis, the shifts are either symmetric in some species or asymmetric in others. We hypothesize that symmetric JAR in T. teniotis serves to avoid jamming and improve echolocation, whereas asymmetric JAR may aid communication by helping to identify and locate conspecifics, thus minimizing chances of mid-air collisions.

Animals↗
PubMed2005

Adaptation of brain regions to habitat complexity: a comparative analysis in bats (Chiroptera).

Vertebrate brains are organized in modules which process information from sensory inputs selectively. Therefore they are probably under different evolutionary pressures. We investigated the impact of environmental influences on specific brain centres in bats. We showed in a phylogenetically independent contrast analysis that the wing area of a species corrected for body size correlated with estimates of habitat complexity. We subsequently compared wing area, as an indirect measure of habitat complexity, with the size of regions associated with hearing, olfaction and spatial memory, while controlling for phylogeny and body mass. The inferior colliculi, the largest sub-cortical auditory centre, showed a strong positive correlation with wing area in echolocating bats. The size of the main olfactory bulb did not increase with wing area, suggesting that the need for olfaction may not increase during the localization of food and orientation in denser habitat. As expected, a larger wing area was linked to a larger hippocampus in all bats. Our results suggest that morphological adaptations related to flight and neuronal capabilities as reflected by the sizes of brain regions coevolved under similar ecological pressures. Thus, habitat complexity presumably influenced and shaped sensory abilities in this mammalian order independently of each other.

Adaptation, Physiological↗