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At least 379 records · Page 21Linked to original sources
PubMed1989

Spinturnicid mites (Gamasida: Spinturnicidae) associated with bats in central Brazil.

The results of a survey of spinturnicid mites (Gamasida: Spinturnicidae) infesting bats near Brasília, D.F., Brazil, are presented. One hundred twenty-five bats were collected, representing three families and 15 species. Seven species of spinturnicid mites (genus Periglischrus) were collected from nine species of bats (family Phyllostomidae). Each of the following six species of Periglischrus was associated with a single species of bat: Periglischrus acutisternus Machado-Allison and P. torrealbai Machado-Allison on Phyllostomus discolor Wagner; P. paravargasi Herrin and Tipton on Anoura caudifer (E. Geoffroy); P. caligus Kolenati on Glossophaga soricina (Pallas); P. ojasti Machado-Allison on Sturnira lilium (E. Geoffroy); P. herrerai Machado-Allison on Desmodus rotundus (E. Geoffroy). P. iheringi Oudemans was collected from four species of bats (Artibeus cinereus (Gervais), A. jamaicensis Leach, A. literatus (Olfers), and Vampyrops lineatus (E. Geoffroy]. No spinturnicids were found on Carollia perspecillata (L.) or on molossid or vespertilionid bats.

Animals↗
PubMed2003

Molecular evolution of bat color vision genes.

The two suborders of bats, Megachiroptera (megabats) and Microchiroptera (microbats), use different sensory modalities for perceiving their environment. Megabats are crepuscular and rely on a well-developed eyes and visual pathway, whereas microbats occupy a nocturnal niche and use acoustic orientation or echolocation more than vision as the major means of perceiving their environment. In view of the differences associated with their sensory systems, we decided to investigate the function and evolution of color vision (opsin genes) in these two suborders of bats. The middle/long wavelength (M/L) and short wavelength (S) opsin genes were sequenced from two frugivorous species of megabats, Haplonycteris fischeri and Pteropus dasymallus formosus, and one insectivorous species of microbat, Myotis velifer. Contrary to the situation in primates, where many nocturnal species have lost the functional S opsin gene, both crepuscular and strictly nocturnal species of bats that we examined have functional M/L and S opsin genes. Surprisingly, the S opsin in these bats may be sensitive to UV light, which is relatively more abundant at dawn and at dusk. The M/L opsin in these bats appears to be the L type, which is sensitive to red and may be helpful for identifying fruits among leaves or for other purposes. Most interestingly, H. fischeri has a recent duplication of the M/L opsin gene, representing to date the only known case of opsin gene duplication in non-primate mammals. Some of these observations are unexpected and may provide insights into the effect of nocturnal life on the evolution of opsin genes in mammals and the evolution of the life history traits of bats in general.

Amino Acid Sequence↗
PubMed1986

Plasma progesterone levels during pregnancy in the little brown bat Myotis lucifugus (Vespertilionidae).

Plasma progesterone was measured by radioimmunoassay in individual female Myotis lucifugus throughout pregnancy and lactation. Progesterone levels, which averaged 6.7 +/- 0.7 ng/ml in late hibernation, rose to a mean of 18.9 +/- 6.7 ng/ml in unimplanted bats collected in the first two weeks after arrival at a maternity roost. Analysis of progesterone levels in bats in which the developmental stage of the embryo was known revealed two sharp, transient increases in plasma progesterone during the preimplantation period. The first, with values of 30-45 ng/ml, occurred at ovulation. The second, with values of 20-30 ng/ml, coincided with blastocyst formation. Progesterone levels increased exponentially from a mean of 7.4 +/- 1.0 ng/ml during early implantation to peak values of 100-200 ng/ml (means = 136.2 +/- 15.6) in the last two weeks of pregnancy, and showed no evidence of either a midpregnancy or prepartum decline. Despite involution of the corpus luteum at the end of pregnancy, progesterone levels averaged 9.0 +/- 1.0 ng/ml during lactation and did not decline until the end of lactation. In bats undergoing abortion, mean levels of plasma progesterone were already less than 6 ng/ml, equivalent to levels in nonbreeding females. The results indicate that the progesterone profile of pregnant M. lucifugus, though generally resembling those of other bats, exhibits several distinctive features. The sharp rise in plasma progesterone coinciding with blastocyst formation has not been reported in other mammals and suggests a possible role of progesterone in the cavitation process. In addition, peak values of plasma progesterone in late pregnancy were conspicuously higher than levels reported in other verpertilionid bats. The levels did not appear to fall before parturition, although such falls have been reported in other bats.

Acclimatization↗
PubMed1994

Tibia fractures produced from the impact of a baseball bat.

Forty-seven patients presented during a 1-year period with fractures of the extremities produced by the impact of a baseball bat. This represented an increase of fourfold in fractures associated with baseball bat trauma as compared with the previous year. Those patients with tibia fractures were retrospectively reviewed in terms of associated soft-tissue injuries, fracture pattern, and fracture healing. Potential force generated and kinetic energy transferred when a baseball bat strikes the tibia were calculated mathematically to provide correlation with clinical observations. Tibia fractures produced by baseball bats represented 10% of all tibia fractures presenting from July 1990-July 1991. Of these 11 tibia fractures, 3 developed compartment syndrome, necessitating fasciotomy and subsequent skin grafting, and 1 developed osteomyelitis, which eventually resulted in amputation. One patient had superficial skin blistering that required a delay in definitive fracture care of 11 days and subsequent skin grafting. There was one nonunion and three delayed unions requiring additional operative intervention. This incidence of compartment syndrome (27%) is nine times higher than the overall incidence, at this institution, of compartment syndrome (3%) in tibia fractures produced by other mechanisms. The maximum potential kinetic energy produced during the impact of a baseball bat is 515 kg/m2/s2: 25% higher than that produced by a 9-mm bullet fired at a distance of 6 ft (407 kg/m2/s2). The potential force transmitted from a bat to the tibia at the time of collision is 8,000 lb, three times that of the bullet (626 lb).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Bats, cats, and rabies in an urban community.

Bats are the primary vectors of rabies in humans in the United States. In the urban environment they generally are found within buildings where they may bite people or be attacked by cats or dogs. Given the high probability that any bat that bites a person may be rabid, antirabies prophylaxis should be administered as soon as possible after the incident. This should not be delayed pending laboratory results on the bat. Children should be taught to avoid contact with moribund bats. Cats are more likely to be involved with rabid bats than dogs, but they are less likely to be vaccinated against rabies. The occasional rabid cat in an urban community may have acquired its infection from a bat. Therefore, it is vital that communities enforce rabies vaccination for cats as well as dogs.

Animals↗
PubMed2000

Persistence of bat defence reactions in high Arctic moths (Lepidoptera).

We investigated the bat defence reactions of three species of moths (Gynaephora groenlandica, Gynaephora rossi (Lymantriidae) and Psychophora sabini (Geometridae)) in the Canadian Arctic archipelago. Since these moths inhabit the Arctic tundra and, therefore, are most probably spatially isolated from bats, their hearing and associated defensive reactions are probably useless and would therefore be expected to disappear with ongoing adaptation to Arctic conditions. When exposed to bat-like ultrasound (26 kHz and 110 dB sound pressure level root mean square at 1 m) flying male Gynaephora spp. always reacted defensively by rapidly reversing their flight course. They could hear the sound and reacted at least 15-25 m away. Psychophora sabini walking on a surface froze at distances of at least 5-7 m from the sound source. However, two out of three individuals of this species (all males) did not respond in any way to the sound while in flight. Hence, we found evidence of degeneration of bat defence reactions, i.e. adaptation to the bat-free environment, in P. sabini but not in Gynaephora spp. Some Arctic moths (Gynaephora spp.) still possess defensive reactions against bats, possibly because the selection pressure for the loss of the trait is such that it declines only very slowly (perhaps by genetic drift; and there may not have been enough time for the trait to disappear. One possible reason may be that Arctic moths have long generation times.

Animals↗
PubMed1998

Base-compositional biases and the bat problem. III. The questions of microchiropteran monophyly.

Using single-copy DNA hybridization, we carried out a whole genome study of 16 bats (from ten families) and five outgroups (two primates and one each dermopteran, scandentian, and marsupial). Three of the bat species represented as many families of Rhinolophoidea, and these always associated with the two representatives of Pteropodidae. All other microchiropterans, however, formed a monophyletic unit displaying interrelationships largely in accord with current opinion. Thus noctilionoids comprised one clade, while vespertilionids, emballonurids, and molossids comprised three others, successively more closely related in that sequence. The unexpected position of rhinolophoids may be due either to the high AT bias they share with pteropodids, or it may be phylogenetically authentic. Reanalysis of the data with varying combinations of the five outgroups does not indicate a rooting problem, and the inclusion of many bat lineages divided at varying levels similarly discounts long branch attraction as an explanation for the pteropodid-rhinolophoid association. If rhinolophoids are indeed specially related to pteropodids, many synapomorphies of Microchiroptera are called into question, not least the unitary evolution of echolocation (although this feature may simply have been lost in pteropodids). Further, a rhinolophoid-pteropodid relationship--if true--has serious implications for the classification of bats. Finally, among the outgroups, an apparent sister-group relation of Dermoptera and Primates suggests that flying lemurs do not represent the ancestors of some or all bats; yet, insofar as gliding of the type implemented in dermopterans is an appropriate model for the evolution of powered mammalian flying, the position of Cynocephalus in our tree indirectly strengthens the argument that true flight could have evolved more than once among bats.

Animals↗
PubMed2005

Genetic population structure of Natterer's bats explained by mating at swarming sites and philopatry.

During autumn 'swarming', large numbers of temperate bats chase each other in and around underground sites. Swarming has been proposed to be a mating event, allowing interbreeding between bats from otherwise isolated summer colonies. We studied the population structure of the Natterer's bat (Myotis nattereri), a swarming species in northern England, by sampling bats at seven sites in two swarming areas and at 11 summer colonies. Analysis of molecular variance (amova) and genetic assignment analyses showed that the swarming areas (60 km apart) support significantly different populations. A negative correlation was found between the distance of a summer colony from a swarming area and the assignment of bats to that area. High gene diversity was found at all sites (HE = 0.79) suggesting high gene flow. This was supported by a low FST (0.017) among summer colonies and the absence of isolation by distance or substructure among colonies which visit one swarming area. The FST, although low, was significantly different from zero, which could be explained by a combination of female philopatry and male-mediated gene flow through mating at swarming sites with bats from other colonies. Modelling suggested that if effective size of the summer colonies (Ne) was low to moderate (10-30), all mating must occur at the swarming sites to account for the observed FST. If the Ne was higher (50), in addition to random mating during swarming, there may be nonrandom mating at swarming sites or some within-colony mating. Conservation of swarming sites that support potentially large populations is discussed.

Animals↗
PubMed2004

Extinction of the acoustic startle response in moths endemic to a bat-free habitat.

Most moths use ears solely to detect the echolocation calls of hunting, insectivorous bats and evoke evasive flight manoeuvres. This singularity of purpose predicts that this sensoribehavioural network will regress if the selective force that originally maintained it is removed. We tested this with noctuid moths from the islands of Tahiti and Moorea, sites where bats have never existed and where an earlier study demonstrated that the ears of endemic species resemble those of adventives although partially reduced in sensitivity. To determine if these moths still express the anti-bat defensive behaviour of acoustic startle response (ASR) we compared the nocturnal flight times of six endemic to six adventive species in the presence and absence of artificial bat echolocation sounds. Whereas all of the adventive species reduced their flight times when exposed to ultrasound, only one of the six endemic species did so. These differences were significant when tested using a phylogenetically based pairwise comparison and when comparing effect sizes. We conclude that the absence of bats in this habitat has caused the neural circuitry that normally controls the ASR behaviour in bat-exposed moths to become decoupled from the functionally vestigial ears of endemic Tahitian moths.

Animals↗
PubMed1985

A pharmacological analysis of the responses of the gastrointestinal smooth muscle of the bat to transmural and periarterial nerve stimulation.

A comparative study of the responses of the gastrointestinal tract of the guinea-pig and of the fruit-eating bat Eidolon helvum to transmural nerve stimulation (TNS) was made. The stomach and rectum of the guinea-pig, the bat and the guinea-pig ileum contracted in response to TNS. These contractions were cholinergic in nature because atropine blocked and physostigmine potentiated them. Tetrodotoxin reversibly abolished these contractions suggesting that they were nerve-mediated. The bat isolated ileum usually responded to TNS with mixed motor and inhibitory components. In some cases, there were only motor or inhibitory components. The motor component was abolished by atropine and potentiated by physostigmine. However, the inhibitory component was non-adrenergic and non-cholinergic (NANC). Tetrodotoxin abolished the motor component without influencing the inhibitory components. Periarterial nerve stimulation of the bat ileum produced a relaxation that was blocked by bretylium, propranolol, phentolamine, reserpine and tetrodotoxin. It is concluded that the bat gastrointestinal smooth muscle, like the guinea-pig, has cholinergic excitatory innervation; however, the bat ileum has both a cholinergic excitatory innervation and a nonadrenergic and non-cholinergic inhibitory component.

Adrenergic Fibers↗
PubMed2006

Effects of selective logging on bat communities in the southeastern Amazon.

Although extensive areas of tropical forest are selectively logged each year, the responses of bat communities to this form of disturbance have rarely been examined. Our objectives were to (1) compare bat abundance, species composition, and feeding guild structure between unlogged and low-intensity selectively logged (1-4 logged stems/ha) sampling grids in the southeastern Amazon and (2) examine correlations between logging-induced changes in bat communities and forest structure. We captured bats in understory and canopy mist nets set in five 1-ha study grids in both logged and unlogged forest. We captured 996 individuals, representing 5 families, 32 genera, and 49 species. Abundances of nectarivorous and frugivorous taxa (Glossophaginae, Lonchophyllinae, Stenodermatinae, and Carolliinae) were higher at logged sites, where canopy openness and understory foliage density were greatest. In contrast, insectivorous and omnivorous species (Emballonuridae, Mormoopidae, Phyllostominae, and Vespertilionidae) were more abundant in unlogged sites, where canopy foliage density and variability in the understory stratum were greatest. Multivariate analyses indicated that understory bat species composition differed strongly between logged and unlogged sites but provided little evidence of logging effects for the canopy fauna. Different responses among feeding guilds and taxonomic groups appeared to be related to foraging and echolocation strategies and to changes in canopy cover and understory foliage densities. Our results suggest that even low-intensity logging modifies habitat structure, leading to changes in bat species composition.

Animals↗
PubMedDate not supplied

Hoxd13 expression in the developing limbs of the short-tailed fruit bat, Carollia perspicillata.

Bat forelimbs are highly specialized for sustained flight, providing a unique model to explore the genetic programs that regulate vertebrate limb diversity. Hoxd9-13 genes are important regulators of stylopodium, zeugopodium, and autopodium development and thus evolutionary changes in their expression profiles and biochemical activities may contribute to divergent limb morphologies in vertebrates. We have isolated the genomic region that includes Hoxd12 and Hoxd13 from Carollia perspicillata, the short-tailed fruit bat. The bat Hoxd13 gene encodes a protein that shares 95% identity with human and mouse HOXD13. The expression pattern of bat Hoxd13 mRNA during limb development was compared with that of mouse. In bat and mouse hindlimbs, the expression patterns of Hoxd13 are relatively similar. However, although the forelimb Hoxd13 expression patterns in both organisms during early limb bud stages are similar, at later stages they diverge; the anterior expression boundary of bat Hoxd13 is posterior-shifted relative to the mouse. These findings, compared with the Hoxd13 expression profiles of other vertebrates, suggest that divergent Hoxd13 expression patterns may contribute to limb morphological variation.

Animals↗
PubMedDate not supplied

Isolation of Candida species from bats in Nigeria.

Eighteen (15%) of 120 Nigerian bats screened for fungal infections yielded yeasts of medical importance from their visceral organs. Candida albicans was the commonest organism recovered from the liver, spleen, kidneys and intestinal contents 1 of 10 out of 40 Glossophaga soricinia bats (nectar-feeding bats). Candida krusei was recovered from the liver and spleen of 3 out of 50 Molossus maior bats (the tropical house bat). Five out of 30 lesser free-tailed bats (Rhinopoma hardwickei hardwickei) yielded mixed isolates of Trichosporon cutaneum and Candida spp. from their liver and spleen. Only Glossophaga soricinia showed evidence of infection of the organs. The liver, spleen and kidneys were covered by white patches of yeast colonies.

Animals↗
PubMed2001

Sound localization in a new-world frugivorous bat, Artibeus jamaicensis: acuity, use of binaural cues, and relationship to vision.

Passive sound-localization acuity and its relationship to vision were determined for the echolocating Jamaican fruit bat (Artibeus jamaicensis). A conditioned avoidance procedure was used in which the animals drank fruit juice from a spout in the presence of sounds from their right, but suppressed their behavior, breaking contact with the spout, whenever a sound came from their left, thereby avoiding a mild shock. The mean minimum audible angle for three bats for a 100-ms noise burst was 10 degrees-marginally superior to the 11.6 degrees threshold for Egyptian fruit bats and the 14 degrees threshold for big brown bats. Jamaican fruit bats were also able to localize both low- and high-frequency pure tones, indicating that they can use both binaural phase- and intensity-difference cues to locus. Indeed, their ability to use the binaural phase cue extends up to 6.3 kHz, the highest frequency so far for a mammal. The width of their field of best vision, defined anatomically as the width of the retinal area containing ganglion-cell densities at least 75% of maximum, is 34 degrees. This value is consistent with the previously established relationship between vision and hearing indicating that, even in echolocating bats, the primary function of passive sound localization is to direct the eyes to sound sources.

Animals↗
PubMed2006

Classification of communication signals of the little brown bat.

Little brown bats, Myotis lucifugus, are known for their ability to echolocate and utilize their echolocation system to navigate, and locate and identify prey. Their echolocation signals have been characterized in detail but their communication signals are less well understood despite their widespread use during social interactions. The goal of this study was to develop an automatic classification algorithm for characterizing the communication signals of little brown bats. Sound recordings were made overnight on five individual male bats (housed separately from a large group of captive bats) for 7 nights, using a bat detector and a digital recorder. The spectral and temporal characteristics of recorded sounds were first analyzed and classified by visual observation of a call's temporal pattern and spectral composition. Sounds were later classified using an automatic classification scheme based on multivariate statistical parameters in MATLAB. Human- and machine-based analysis revealed five discrete classes of bat's communication signals: downward frequency-modulated calls, steep frequency-modulated calls, constant frequency calls, broadband noise bursts, and broadband click trains.

Algorithms↗
PubMed1989

The acoustic basis for target discrimination by FM echolocating bats.

Past experiments show that echolocating bats of the species Myotis lucifugus and Eptesicus fuscus can discriminate among airborne sonar targets presented in the context of pursuit maneuvers for the interception of prey. These bats distinguish between edible mealworms and inedible spheres of various sizes. Myotis can distinguish between disks and mealworms similar enough in size that the bat's performance requires the ability to perceive the acoustic equivalent of target shape. Previously observed small differences in the spectrum of echoes from mealworms and disks appear insufficient to distinguish these targets at the performance levels achieved by bats. We measured the acoustic properties of the targets by broadcasting ultrasonic impulses at mealworms, spheres, and disks and recording their echoes, displaying the results in terms of impulse echo waveforms and the frequency response of targets derived from the target transfer function. The echoes from disks and mealworms at various orientations convey the range-axis profile of the target (number and spacing of reflecting points or glints distributed at different ranges) in terms of the impulse structure of their waveforms and in terms of the locations and spacing of notches or nulls in their spectra. For targets that bats can discriminate and that reflect echoes which do not clearly differ in overall amplitude, the targets appear distinguishable from the acoustic representation of their range profile, which is a feature of targets that bats can perceive with great acuity.

Animals↗
PubMed1998

Spontaneous classification of complex tones at high and ultrasonic frequencies in the bat, Megaderma lyra.

Megaderma lyra, a bat species using harmonically structured calls for echolocation, exploits the spectral content of its echoes for texture discrimination. It is the aim of the present study to test according to which sensory qualities harmonic complex tones are spontaneously classified by this bat. The applied experimental paradigm is especially adapted to the preference of M. lyra to use absolute pitch cues. Three animals were trained in a 2-AFC procedure to classify three-component stimuli as low or high, with all their harmonics below or above a pure tone reference of 33 kHz, respectively. Later, the original tones were interspersed with "incomplete" test stimuli, with their fundamentals (and lower harmonics) missing. These were ambiguous in that their possible virtual, i.e., collective pitches were below the reference whereas their pure tone pitches were above it. Bat 1 classified 22 of 23 test stimuli with missing fundamentals between 5.3 and 28.3 kHz according to their collective pitches, whereas bat 2 judged all presented ambiguous tones on the basis of their pure tone pitches. Bat 3 failed the pitch control criterion which is why in this case results cannot be interpreted unequivocally. The implications of these findings are discussed with respect to the bats' behavioral context, as well as to psychoacoustical models of the formation of the pitch of complex tones.

Animals↗
PubMed2000

Range discrimination by big brown bats (Eptesicus fuscus) using altered model echoes: implications for signal processing.

The sonar emissions of two big brown bats (Eptesicus fuscus) were modeled to create a "normal" echolocation signal for each bat which was then used as an artificial echo to synthesize a phantom target. The bat's task was to indicate which of two phantom targets (presented singly) was the "near" target and which the "far" target. Threshold range discrimination at a nominal target distance of 80 cm was about 0.6 cm for both bats. The normal signal was then modified to change the relative energy in each harmonic, the signal duration, the curvature of the frequency sweep, the absolute frequency, the phase of the second and third harmonics relative to the first, or the Doppler shift of the signal. To determine which modifications affected ranging performance, the altered models were used in tests of range discrimination that were interleaved on a day-to-day basis with tests using the normal model. Of the 12 modifications tested, only those changing the curvature of the frequency sweep affected performance. This result appears not to be predicted by current models of echo processing in FM bats. Eptesicus may be able to compensate for certain types of distortions of a returning echo, an ability possibly related to Doppler tolerance or to the characteristics of the natural variation in a bat's emissions.

Animals↗