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At least 847 records · Page 47Linked to original sources
PubMed2005

The adjuvant activity of BAT antibody enables DNA vaccination to inhibit the progression of established autochthonous Her-2/neu carcinomas in BALB/c mice.

Over the course of 33 weeks from birth, the mammary glands of virgin female BALB/c mice transgenic for the transforming rat Her-2/neu oncogene progress from atypical hyperplasia to invasive carcinoma. By week 12, all their mammary glands display many foci of in situ carcinoma. DNA vaccination at weeks 12 and 14 through in vivo electroporation of a plasmid encoding for the extracellular and transmembrane domain of the protein product of rat Her-2/neu oncogene kept 33% of mice tumor-free until week 35, when the experiment ended. To improve its efficacy the vaccine was combined with a T cell stimulatory monoclonal antibody (BAT). When each plasmid electroporation was followed by intravenous administration of 10 microg of BAT monoclonal antibody at weeks 13 and 15, 55% of mice remained tumor free (p < 0.0001) and stronger T cell and antibody-mediated immune responses were elicited. These data suggest that costimulation by BAT monoclonal antibody enables DNA vaccination to establish an effective protection against incipient carcinomas.

3T3 Cells↗
PubMed2006

Cross-sectional geometry of the dentary in bats.

Bats exhibit remarkable diversity in dietary habits, with species specializing on insects, fruit, nectar, vertebrates and blood. Studies of larger mammals have shown that structural differences in dentary cross-sectional properties exist among species with different diets. Unfortunately, few of these studies have considered the role of phylogeny in shaping these apparent form-function associations. Here we ask whether a relationship exists between diet and dentary structure in bats when phylogenetic history is factored into the analysis. To answer this question, we compared results from phylogenetic generalized least squares (PGLS) and traditional (nonphylogenetic) regression analyses of dentary cross-sectional shape in frugivorous, nectarivorous, and insectivorous bats (253 individuals representing 72 species). Cross-sectional moments of inertia of the dentary between M(1) and M(2) were computed from bone densitometry scans of skeletal specimens. Traditional regressions of cross-sectional parameters against dentary length detected significant departures from isometry among frugivores. In contrast, PGLS analyses indicated that cross-sectional variables for each dietary group scaled with isometry. Thus, the allometric patterns illuminated by traditional statistics are linked to the phylogenetic structure of the sample. Identical patterns of significant differences in slopes and intercepts between frugivores and nectarivores emerged from both traditional and PGLS analyses. As predicted, the cross-sectional shape of the dentary in frugivores is consistent with increased resistance to torsion and bending, while that of nectarivores suggested a less resistant dentary. Although traditional and PGLS analyses yielded some similar results, the phylogenetic structure of a sample can drive apparent patterns of scaling and should be considered in comparative functional analyses.

Animals↗
PubMed2006

Hormonal induction of ovulation stimulates atresia of antral follicles in a vespertilionid bat, Scotophilus heathi.

Scotophilus heathi is a seasonally monoestrous subtropical vespertilionid bat found at Varanasi, India. Although the antral follicles remain present in the ovaries of S. heathi from November till March, ovulation is delayed in this species until early March. In order to understand the mechanism of ovulation suppression during this period of delayed ovulation, the effects of human chorionic gonadotropin (hCG), pregnant mare's serum gonadotropin (PMSG), follicle stimulating hormone (FSH) and gonadotropin releasing hormone agonist (GnRH agonist) on ovarian morphology and steroid concentration were investigated. Hormonal treatments were given as a single i.p. dose 24 h after capture. The bats were sacrificed 48 h after the injection. Treatment with hCG, PMSG, FSH and GnRH agonist failed to induce ovulation in S. heathi, although these hormones produced a high degree of ovarian stimulation. The administration of hCG and PMSG induced ovarian enlargement, intense hyperemia, marked changes in the interstitial cells (ICs), development of several antral follicles and a varying degree of abnormalities in the oocytes of most of the antral follicles. In the bats treated with hCG, PMSG and GnRH agonist, androstenedione concentration increased significantly to extraordinarily high levels, whereas estradiol concentration decreased. Administration of FSH caused regression of ICs and pyknosis of granulosa cells in the majority of antral follicles. FSH did not enhance androstenedione concentration. The results of the present study suggest that the failure of hormonal treatments to induce ovulation during the period of delayed ovulation might be due to a seasonal desensitization of ovarian follicles in S. heathi. The hormonal treatment instead stimulated the ICs to produce a high level of androstenedione resulting in atretic changes of the antral follicles.

Animals↗
PubMed2006

Relationships between renal morphology and diet in 26 species of new world bats (suborder microchiroptera).

The renal morphology of 24 species of mormoopid and phyllostomid bats feeding on six different diets was examined to test evolutionary changes in several structural traits presumably led by dietary shifts from ancestral insectivorous diets. The kidneys of a fish-eating vespertilionid and an insect-eating emballonurid were also examined but not included in the phylogenetic comparison. The length, width, and breadth of the kidneys were used to calculate relative medullary thickness (RMT). Tissues were processed for stereological analysis, and the volumes of the kidney, nephron components, and vasculature were determined. RMT did not correlate with body mass in either animal-eating or plant-eating phyllostomid and mormoopid bats. The shift from insectivory to frugivory and nectarivory was accompanied by a reduction in RMT, a reduction in the percent of renal medulla, and an increase in the percent of renal cortex. No changes in these traits were observed in bats that shifted to carnivorous, omnivorous or sanguinivorous habits. No changes were observed in renal vasculature, in the percentage of cortical and medullary nephron components or of capillaries surrounding the nephrons in any feeding group. Vespertilionid and emballonurid species had similar values in all traits examined as compared to insectivorous phyllostomids and mormoopids. Our data suggest that diet does not influence a single area of the nephron, but rather the entire nephron such that the relative amounts of renal cortex and medulla are affected.

Animals↗
PubMed2003

The effect of bicuculline application on azimuth-dependent recovery cycle of inferior collicular neurons of the big brown bat, Eptesicus fuscus.

The recovery cycle of auditory neurons is an important neuronal property, which determines a neuron's ability to respond to pairs of sounds presented at short inter-sound intervals. This property is particularly important for bats, which rely upon analysis of returning echoes to extract the information about targets after emission of intense orientation sounds. Because target direction often changes throughout the course of hunting, the changing echo direction may affect the recovery cycle and thus temporal processing of auditory neurons. In this study, we examined the effect of sound azimuth on the recovery cycle of inferior collicular (IC) neurons in the big brown bat, Eptesicus fuscus, under free-field stimulation conditions. Our study showed that the recovery cycle of most IC neurons (42/49, 86%) was longer when determined with sounds delivered at 40 degrees ipsilateral (i40 degrees ) than at 40 degrees contralateral (c40 degrees ) to the recording site. To study the contribution of GABAergic inhibition to sound azimuth-dependent recovery cycle, we compared the recovery cycle of IC neurons determined at two sound azimuths before and during iontophoretic application of bicuculline, an antagonist for GABA(A) receptors. Bicuculline application produced a greater decrease of the recovery cycle of these neurons at i40 degrees than at c40 degrees. As a result, the azimuth-dependent recovery cycle of these neurons was abolished or greatly reduced. Possible mechanisms underlying these observations and biological relevance to bat echolocation are discussed.

Acoustic Stimulation↗
PubMed1991

Brown (BAT) and white (WAT) adipose tissue in high-fat junk food (HFJF) and chow-fed rats with dorsomedial hypothalamic lesions (DMNL rats).

Male weanling rats received dorsomedial hypothalamic nucleus lesions (DMNL) or sham operations and were fed for 173 postoperative days a high-fat diet and given a 32% sucrose solution as drinking fluid. This was supplemented with chocolate chip cookies, potato chips and marshmallows. Other DMNL and sham-operated controls were fed lab chow instead of the above high-fat junk food diet (HFJF) and given tap water instead of 32% sucrose solution. All animals were killed on postoperative day 174. Caloric intake per 100 g body weight was similar in all groups; however, the HFJF fed control and DMNL rats had significantly elevated carcass fat. Since HFJF-DMNL rats were not nearly as obese as the HFJF control animals, it appears that the DMNL offered some protection against the HFJF-diet-produced obesity. When their smaller body size is considered. DMN lesions had no effect on brown adipose tissue (BAT) mass in chow-fed or HFJF fed rats, whereas BAT size was significantly enlarged in HFJF-fed control animals. This suggests but does not prove that HFJF-fed controls, but not DMNL rats, may be using dietary-induced thermogenesis (DIT) to attenuate their obesity. We hypothesize that the HFJF-fed DMNL may not be enhancing DIT as reflected in normal BAT size, because they had not attained a degree of fatness to activate this system, or the DMN lesions impaired its activation. Both HFJF-fed groups showed reduced linear growth compared to their counterparts. The reason for stunting is uncertain, but may be related to their low plasma insulin concentrations.

Adipose Tissue↗
PubMed1998

Characterisation of a novel lyssavirus isolated from Pteropid bats in Australia.

A novel lyssavirus isolated from Pteropid bats in Australia (Australian Bat Lyssavirus, ABLV) has been characterised using gene sequence analyses, electron microscopy and a panel of monoclonal antibodies. Electron microscopic examination of Pteropid bat and mouse brain material as well as virus isolated from tissue culture medium, showed the presence of bullet-shaped rhabdovirus particles and structures characteristic of lyssavirus. Analysis using nucleocapsid (N) specific monoclonal antibodies, showed a strong relationship between this new lyssavirus and serotype 1 rabies. The nucleotide sequence of the prototype strain of ABLV was determined from the initiator methionine codon for the nucleocapsid protein (N protein) to the amino terminus of the polymerase gene (L protein), a distance of 5344 nucleotides. Comparisons of the deduced N, phosphoprotein (P), matrix protein (M), and glycoprotein (G) proteins showed that ABLV was more closely related to serotype 1 classic rabies viruses than to other members of the Lyssavirus genus. The percent relatedness of the ABLV proteins when compared to the cognate proteins of PV (Pasteur vaccine strain) rabies was 92, 75, 87 and 75% for the N, P, M and G proteins, respectively. Phylogenetic studies of N protein sequences showed clearly that ABLV is an unrecognised member of the Lyssavirus genus and represents a new genotype, genotype 7.

Amino Acid Sequence↗
PubMed1998

Experimental rabies infection and oral vaccination in vampire bats (Desmodus rotundus).

A rabies virus variant isolated from a vampire bat (Desmodus rotundus) and characterized by genome sequencing was used for the standardization of an experimental infection in this species. The parenteral administration of 10(6) MICLD50 of this variant was capable of inducing death from rabies in 89% of animals. The mean duration of post-challenge survival was 12 days. None of the experimental rabid vampire bats showed aggressive behaviour. A vaccinia-rabies glycoprotein recombinant virus vaccine was administered orally to vampire bats on days -120, -90, -30 or -18 pre-challenge, on the same day of challenge, or on day +5 post-challenge. A significant protection was noticed only in animals vaccinated on days -18 or -30 pre-challenge. A longer period of incubation was observed in animals vaccinated 5 days post-challenge.

Administration, Oral↗
PubMedDate not supplied

[Hypersensitivity pneumonitis induced in guinea pigs by antigens to bat feces].

A bat feces extract was able to induce the synthesis of specific IgG in rabbits and IgE in atopics. These findings were corroborated by skin tests, RAST and RAST-inhibition. Nowadays, data concerning the experimental induction of hypersensitivity pneumonitis using a glycoprotein of bat feces are presented. This antigen was aerosolized for inhalation by adult guinea pigs for 12 weeks to detect specific serum IgM, IgG and IgE antibodies as well as sensitized T-CD4 cells. Histopathological studies of the lungs showed interstitial infiltrates of macrophages and lymphocytes, cellular bronchiolitis and single non-necrotizing granulomas from the seventh to the ninth weeks. From the tenth week to the end of the experiment the lesions of the lungs progressively worsened. The results from this animal model suggest that the chronic contact with the bat feces'antigen can induce other inflammatory lung reactions than those IgE dependant.

Aerosols↗
PubMedDate not supplied

Proteinase and gelatinolytic properties of a bat feces extract.

It was previously demonstrated that a bat feces extract (BAT) was able to produce a specific IgG in animals, a specific IgE in respiratory atopic humans and a hypersensitivity pneumonitis in guinea pigs. As numerous allergens (such as house-dust mite, cockroaches and pollens) revealed a enzymatic activity measured by different assays we decided to study the proteinase and the gelatinolytic activities of the BAT. Several protease inhibitors such as E-64, TLCK, TPCK, PMSF, leupeptin, o-phenantroline and pepstatin-A were applied to establish the chemical properties of the enzymatic activity. These assays revealed a serine-trypsin-like proteolytic and gelatinolytic activities specially at pH 8,5. On the other hand, two bands of 21 and 40 kDa reacted with the human atopic sera suggesting a possible correlation between allergenicity and proteinase activity. Their role in the etiology of perennial rhinitis and asthma requires further investigations.

Allergens↗
PubMed1998

Expression of biological activity of draculin, the anticoagulant factor from vampire bat saliva, is strictly dependent on the appropriate glycosylation of the native molecule.

Draculin, a glycoprotein isolated from vampire bat (Desmodus rotundus) saliva, is a natural anticoagulant which inhibits activated coagulation factors IX (IXa) and X (Xa). The observation that under captivity conditions, the anticoagulant activity present in vampire bat saliva is dependent upon the salivation protocol, led us to investigate the possible relationship between the expression of biological activity of native draculin and the post-translational glycosylation of the protein backbone. Daily salivation of vampire bats yields a saliva that progressively decreases in anticoagulant activity, without any significant change in overall protein content, or in the amount of protein specifically recognized by a polyclonal anti-draculin antibody. Anticoagulant activity of the saliva is restored after a 4-day period of rest. Besides the marked difference in anticoagulant activity, purified native draculin, obtained from high- and low-activity saliva, shows significant differences in: (a) composition of the carbohydrate moiety, and (b) Glycosylation pattern. Furthermore, controlled chemical deglycosylation of native draculin, under conditions that do not affect the polypeptide backbone, progressively leads to complete loss of the biological activity. Our present results implicate that correct glycosylation of draculin is a seminal event for the expression of the biological activity of this glycoprotein.

Animals↗
PubMed2002

The effect of sound duration on rate-amplitude functions of inferior collicular neurons in the big brown bat, Eptesicus fuscus.

During echolocation, the amplitude and duration of echo pulses of the big brown bat, Eptesicus fuscus, covary throughout the entire course of hunting. The purpose of this study was to examine if variation in sound duration might affect the amplitude selectivity of inferior collicular (IC) neurons of this bat species under free-field stimulation conditions. A family of rate-amplitude functions of each IC neuron was obtained with different sound durations. The effect of sound duration on the neuron's amplitude selectivity was then studied by examining the type, best amplitude, dynamic range and slope of each rate-amplitude function. The rate-amplitude functions of 83 IC neurons determined with different sound durations were either monotonic, saturated or non-monotonic. Neurons with monotonic rate-amplitude functions had the highest best amplitude, largest dynamic range but smallest slope. Neurons with non-monotonic rate-amplitude functions had the lowest best amplitude, smallest dynamic range but largest slope. The best amplitude, dynamic range and slope of neurons with saturated rate-amplitude functions were intermediate between these two types. Rate-amplitude functions of one group (47, 57%) of IC neurons changed from one type to another with sound duration and one-third of these neurons were tuned to sound duration. As a result, the best amplitude, dynamic range, and slope also varied with sound duration. However, rate-amplitude functions of the other group (36, 43%) of IC neurons were hardly affected by sound duration and two-thirds of these neurons were tuned to sound duration. Biological relevance of these findings in relation to bat echolocation is discussed.

Acoustic Stimulation↗
PubMed1996

The early postnatal development of F-actin patterns in the organ of Corti of the gerbil (Meriones unguiculatus) and the horseshoe bat (Rhinolophus rouxi).

The arrangements of F-actin in hair cells and non-sensory cells were studied in paraformaldehyde-fixed cochleae of horseshoe bats and gerbils in several postnatal stages and in the adult. Phallotoxin-labeled midmodiolar cryostat sections of the organ of Corti were analyzed with confocal fluorescence microscopy. In both species, the arrangement of F-actin in the adult organ of Corti was essentially similar to that described in other mammals; however, both species showed their own species-typical specializations in staining of the Deiters cells. In the gerbil, a distinct baso-apical gradient in morphology and staining properties was found in the upper compartment of the Deiters cells. In the bat, F-actin label within the Deiters cups was most pronounced in the basal cochlear turn and less abundant in the apical turns. During the first postnatal week, the sensory epithelium of the gerbil lacked the tunnel of Corti and the spaces of Nuel. Only the reticular lamina and the surface of the greater epithelial ridge were intensely labeled for F-actin. At 9 days after birth (DAB), when the tunnel of Corti and the inner spiral sulcus were formed, the footplates of Deiters and pillar cells and the apices of pillar cells began to show intense F-actin label. At 12 DAB, corresponding to onset of hearing, F-actin staining was found throughout the supporting cell bodies, but was less intense than in the adult. The specialized upper compartment of the Deiters cells differentiated around 15-20 DAB. In the neonate bat, gross-morphology of the organ of Corti was almost adult-like, but only the reticular lamina and the head- and footplates of pillar cells showed intense F-actin staining. The F-actin cytoskeleton of the Deiters cells bodies was poorly developed. At the onset of hearing (between 3rd and 5th DAB), supporting cells showed only a slight increase of F-actin mainly at mechanically important cell regions, namely the Deiters cups, the contact zone of pillar headplates and the footplates of supporting cells. The most intense increase of F-actin occurred between onset of hearing and 16 DAB. At 16 DAB, the F-actin distribution within the supporting cells was similar to the adult. In both species, there were no clear baso-apical gradients in development of F-actin patterns. It is proposed that F-actin insertion in supporting cells after the onset of hearing contributes to maturation of cochlear function.

Actins↗
PubMed1998

Processing of sinusoidally frequency modulated signals in the nuclei of the lateral lemniscus of the big brown bat, Eptesicus fuscus.

Neurons in the nuclei of the lateral lemniscus (NLL) of the big brown bat, Eptesicus fuscus, show several distinctive patterns of response to unmodulated tones. Previous work suggests that sustained responders are specialized to transmit information about sound level and duration while onset responders transmit precise timing information. The biosonar signals of E. fuscus consist of multiple, downward frequency modulated sweeps that change in slope and repetition rate as the bat approaches a target. An obvious hypothesis would be that NLL neurons with sustained responses should discharge during the time when the frequency of a signal is within their response area, but that onset responders should discharge each time the frequency enters the excitatory portion of their response area. In this study we examined the responses of NLL neurons to sinusoidally frequency modulated (SFM) signals presented monaurally to awake, restrained bats. Extracellular recordings were obtained from single neurons in the multipolar and columnar divisions of the ventral nucleus (VNLLm and VNLLc), the intermediate nucleus (INLL) and the dorsal nucleus of the lateral lemniscus (DNLL). All NLL neurons responded synchronously to SFM signals under some conditions. The temporal precision of synchronization was quantified using a coefficient of synchronization (CS), where a value of I equals perfect synchrony. Maximum CS values ranged from 0.70 to >0.99, were generally highest at low modulation rates ( <200 Hz), and showed lowpass characteristics for modulation rate. The maximal modulation rates that elicited synchronous discharge ranged from 50 to 500 Hz. The highest maximal rates were found in the VNLLm and VNLLc, the lowest in DNLL. The ability of NLL neurons to synchronize their discharge to the pattern of an SFM signal is intermediate between that of neurons in the cochlear nucleus and in the inferior colliculus. For the majority of neurons in VNLLm, INLL and DNLL, the precision of synchronization was approximately equal for the downward and upward components of the SFM signal; in contrast, 69% of VNLLc neurons responded selectively to the downward component of the SFM signal. All VNLLc neurons and a subset of those in VNLLm, INLL, and DNLL responded synchronously to SFM signals only if the frequency excursions included a border of the excitatory frequency bandwidth, suggesting that the synchronous discharge was due primarily to the repeated passage of the stimulus frequency into and out of the excitatory portion of the response area. In the case of VNLLc neurons, only the high frequency border was effective; Other neurons, especially those in DNLL, responded synchronously to SFM signals with frequency excursions that were confined entirely within the excitatory response area.

Acoustic Stimulation↗
PubMed1991

The role of positive and negative interspecific associations in the organization of communities of intestinal helminths of bats.

Twelve populations of bats were examined to determine the extent of interspecific associations in determining the species richness of intestinal helminth infracommunities. The pool of helminth species which was available to individual bats ranged from 2 to 21. The 'summed binomial' distribution was determined to underlie the host frequency distribution of the number of helminth species per host. Overall covariation in occurrences of species in replicated communities can be detected by testing for the equality of the observed variance of the host frequency distribution to the variance expected when species are allocated to hosts at random. Where statistically significant the covariance was indicative of a majority of positive rather than negative interspecific associations. As the mean number of species per host in a host population increases not only does the number of positive associations increase but so does the proportion of species pairs which exhibit positive associations. Although there is an increase in the proportion of species pairs which exhibit positive associations as the number of species increases, the magnitude of the associations (as indicated by the mean positive or the mean negative pairwise covariances) does not. Therefore, we concluded that positive interactions are more common than negative interactions in determining the species richness of helminth infracommunities of bats. Further, positive associations become even more important as the community becomes more complex. However, the increased importance is derived from the number rather than the strength of the associations.

Animals↗
PubMed2005

Salivary excretion of rabies virus by healthy vampire bats.

Salivary excretion of rabies virus was evaluated in 14 adult vampire bats (Desmodus rotundus) intramuscularly injected with a large dose (10(6) MICLD50) of vampire rabies virus variant CASS88. Saliva samples were obtained from surviving bats every other day for 30 days, then weekly for 2 months, and finally 1 and 2 years later. Rabies virus was isolated in murine neuroblastoma cells and in randomly selected cases by PCR. Rabies virus was not detected in the saliva of any of the 11 animals that succumbed (somewhat early) to rabies challenge, nor in the control bats. In contrast, virus was detected early, and only once (days 6, 6 and 21) in each of the three animals that survived rabies challenge and remained healthy for at least 2 years after challenge. At that time even vigorous dexamethasone and cyclosporine administration failed to provoke further viral excretion.

Animals↗
PubMed2003

Attraction of the fruit-eating bat Carollia perspicillata to Piper gaudichaudianum essential oil.

We performed field tests using mimetic Piper fruits with and without essential oil extracted through hydrodistillation from Piper gaudichaudianum ripe fruits in order to evaluate the role of odor in Carollia perspicillata attraction and capture in mist-nets. During the field tests, 26 C. perspicillata were captured, 21 (80.7%) in nets with the essential oil of P. gaudichaudianum and five (19.3%) in nets without oil. Other bat species, Artibeus spp. (67), which is specialized on fruits of Moraceae, and Sturnira lilium (10), specialized on those of Solanaceae, were also captured, but they exhibited no significant preference for nets with or without oil. We conclude that odor is pre-eminent over visual cues in food location by C. perspicillata in a field situation. Based on the result, we propose the extraction and use of essential oils of chiropterochoric fruits as a useful approach to improve autoecological studies on fruit-eating bats and to promote tropical forest restoration through the attraction of frugivorous bats to degraded areas.

Animals↗
PubMed1997

Intrinsic and required dynamics of a simple bat-ball skill.

Three experiments investigated the coordination dynamics of a simple bat-and-ball skill: cyclically striking a ball suspended by a string with a pendular bat. The relative phase phi between the bat and ball is dictated by the potential function V(phi) = k sin phi and the difference delta omega in their uncoupled frequencies. For various delta omega, phi and its standard deviation were measured in the absence of any environmental restraints (intrinsic dynamics) and when the ball had to reach resistive or nonresistive targets at set distances (required dynamics). Results support the dynamical theory of coordination patterns (G. Schöner & J.A.S. Kelso, 1988a, 1988c), particularly the hypothesis that required dynamics are understandable as the addition of terms to the potential governing the intrinsic dynamics.

Biomechanical Phenomena↗