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PubMed2025

Extensive longevity and DNA virus-driven adaptation in nearctic Myotis bats.

The genus Myotis is one of the largest clades of bats, and exhibits some of the most extreme variation in lifespans among mammals alongside unique adaptations to viral tolerance and immune defense. To study the evolution of longevity-associated traits and infectious disease, we generated cell lines and near-complete genome assemblies for 8 closely related species of Myotis. Using genome-wide screens of positive selection, analyses of structural variation, and functional experiments in primary cells, we identify new patterns of adaptation contributing to longevity, cancer resistance, and viral interactions in bats. We show that the recurrent evolution of longevity seen in Myotis leads to some of the highest predicted increases in cancer risk across mammals and demonstrate a unique DNA damage response in primary cells of the long-lived M. lucifugus. We also find evidence of abundant adaptation in response to DNA viruses - but not RNA viruses - in Myotis and other bats in sharp contrast with other mammals, potentially contributing to the role of bats as reservoirs of zoonoses. Together, our results demonstrate how genomics and primary cells derived from diverse taxa uncover the molecular bases of extreme adaptations in non-model organisms.

Aging↗
PubMed1979

Bat-associated histoplasmosis in Maryland bridge workers.

An epidemic of acute prolonged febrile respiratory disease affecting nine of 19 workers on a Maryland State bridge maintenance crew was diagnosed as histoplasmosis by serologic testing in all and by isolation of the organism in one. In our investigation, it was revealed that work on a particular bridge was associated with disease. Culture of bat guano from the site two months later revealed H. capsulatum. Four previously uninfected epidemiologic investigators also became ill with histoplasmosis following collection of soil and bat guano. This outbreak reveals that bats and bat guano are a source of histoplasmosis, suggests that only brief exposure is necessary for acute infection and reemphasizes that histoplasmosis is not confined to the midwestern states.

Animals↗
PubMed1978

Dieldrin-induced mortality in an endangered species, the gray bat (Myotis grisescens).

Brains of juvenile gray bats, Myotis grisescens, found dead beneath maternity roosts in two Missouri caves contained lethal concentrations of dieldrin. One colony appeared to be abnormally small, and more dead bats were found a year after the juvenile bats had been collected. This is the first report to link the field mortality of bats directly to insecticide residues acquired through the food chain.

Aldrin↗
PubMed1979

Target range-sensitive neurons in the auditory cortex of the mustache bat.

Echolocating bats determine distance to targets by the time delay between their emitted biosonar pulses and the returning echoes. By varying the delay between synthetic pulses and echoes in stimulus pairs at various repetition rates and durations, neurons have been found in the auditory cortex of the mustache bat (Pteronotus parnellii rubiginosus) which are sensitive to target range during the search, approach, and terminal phases of prey capture or landing. Two classes of range-sensitive neurons were found: (i) tracking neurons, whose best delay for response to an echo following the emitted pulse becomes shorter and narrower as the bat closes in on the target, and (ii) range-tuned neurons, whose best delay is constant, and which respond to the target only when it is within a certain narrow fixed range. Range-tuned neurons are specialized for processing echoes only during a particular period of the search, approach, or terminal phases of echolocation, and they provide support for a theory of ranging in bats that incorporates groups of neurons with a spectrum of preferred echo delays to detect target distance.

Action Potentials↗
PubMed1978

Electron microscope study on the hepatic sinusoidal wall and fat-storing cells in the bat.

The three cell types known to form the hepatic sinusoidal wall were electron microscopically observed in three kinds of bats captured in winter and summer. 1. The cytoplasmic extensions of sinusoidal endothelial cells consisted of continuous thicker parts ("cytoplasmic processes") and discontinuous thinner parts ("sieve plates"). The alternate disposition of the two parts was rather irregular, and the sizes, shapes and spacings of the fenestrae were variable. In the thinner parts with numerous small fenestrae, larger gaps were also mingled. The endothelium was simple-layered and devoid of basal lamina. Interendothelial junctions were found mainly between closely apposed margins of the "cytoplasmic processes" and agreed in structure with the "junctional complex" of WISSE (1970). 2. Kupffer cells, morphologically distinct from the endothelial cells, bulged strongly into the sinusoidal lumen. Provided with many microvillous pseudopods, they were stellate in appearance. They were fixed to the endothelial lining by small junctional areas which occurred between the Kupffer cell body and the "cytoplasmic processes" of the endothelium. 3. Fat-storing cells were located in the Disse's space. They generally contained only smaller amounts of lipid in a few droplets. So-called empty fat-storing cells were numerous, especially in winter bats. The perikaryonal cytoplasm revealed a large Golgi complex and well-developed granular endoplasmic reticulum. The three mesenchymal cell types of the sinusoidal wall possessed the centriole in common within the Golgi complex, but only the fat-storing cell was provided with the single cilium. Fat-storing cells extended cytoplasmic processes ramifying beneath the endothelial lining occasionally surrounding the sinusoids almost completely, and which seemed to reinforce the endothelial lining and to bring about the constriction of the sinusoid. In hypervitaminotic bats that daily received 6,000 I.U. vitamin A for three days, remarkable increase in size and number of lipid droplets was observed in slightly hypertrophic fat-storing cells, and the empty cells disappeared simulating an increased number of fat-storing cells. Suggestion was made of an antidotal function of fat-storing cells against excess vitamin A which might be considered a toxic agent in the broad sense. 4. The Disse's space of bat liver contained plasma cells, lymphocytes and macrophages, the latter too often being under migration through the endothelial fenestrae.

Animals↗
PubMed1978

Occurrence of centrioles in interphasic hepatocytes of bat and chicken.

Occurrence of centrioles in non-dividing hepatocytes was examined by electron microscopy in the bat, Miniopterus schreibersi (Kuhl) and Myotis macrodactylus (Temminck), and the chicken. In both species centrioles were mostly found in the apical hyaloplasmic halo which was distinct in the chicken but rather indistinct in the bat. There was no difficulty in locating centrioles in the hepatocytes of either species. In the chicken centrioles were found in the attenuated apical cytoplasmic areas of 4-6 hepatocytes surrounding the bile canaliculus, giving us the impression that the occurrence of centrioles in non-dividing hepatocytes might be more frequent in the chicken than in the bat. The centrioles found in non-dividing bat and chicken hepatocytes apparently formed diplosomes. Neither multiple centrioles (comprising more than three) nor centriolar replications were found. Single cilium formation from the centrioles was not observed in either species.

Animals↗
PubMed1978

Humoral and cell-mediated immunity to Histoplasma capsulatum during experimental infection in neotropical bats (Artibeus lituratus).

The humoral and cell-mediated immune responses of the large, frugivorus bat, Artibeus lituratus, were studied following intraperitoneal injection of 10 or 10(4) viable mycelial particles of Histoplasma capsulatum. Most bats had both cultural and histologic evidence of disease at autopsy. Utilizing a technique designed to measure the volume of footpad swelling in hypersensitive bats a significant degree of delayed hypersensitivity to histoplasmin was evident in both groups 4 to 6 wk after infection. Precipitating antibodies first appeared in the serum 3 wk after infection, but only in the animals infected with 10(4) viable organisms. Both the double diffusion and counterimmunoelectrophoresis techniques for antibody gave identical results. These findings suggest that A. lituratus is very susceptible to infection with H. capsulatum, and that a mild infection will stimulate delayed hypersensitivity to the organism but only low levels of antibody. The footpad test utilized in this study may be a sensitive and practical method for detecting natural infection in bats.

Animals↗
PubMed1979

Immune responses in bats following intranasal infection with Histoplasma capsulatum.

Groups of bats (Artibeus lituratus) were infected by the intranasal instillation of a suspension of mycelia and spore particles of Histoplasma capsulatum containing either 10(4) or 10(6) viable units. Bats infected with the high dose had viable H. capsulatum in the lungs, liver, spleen and gut as early as 2 weeks post-infection. Complement-fixing antibodies to the organism were detectable 3 weeks after infection, whereas precipitating antibodies were not persent until 5 weeks. Significantly delayed hypersensitivity to histoplasmin was noted at 2 and 4 weeks after infection. By 9 weeks, delayed hypersensitivity had waned, while antibodies could still be demonstrated. The observation that bats are susceptible to respiratory infection with H. capsulatum suggests a mechanism by which the disease may be maintained within a colony. Delayed hypersensitivity appears to be a sensitive, but transient, indicator of active histoplasmosis in bats.

Animals↗
PubMed1977

Rabies virus and antibody in bats in Grenada and Trinidad.

Rabies virus was detected by fluorescent-antibody and mouse inoculation tests in the brain of one bat, Artibeus jamaicensis, collected at La Tante, Grenada on 19 June 1974. No rabies virus was found in the brains and/or salivary glands of 411 other Grenadian bats of 6 species tested, including 56 A. jamaicensis. Rabies neutralizing antibody was detected by the rapid fluorescent focus inhibition test (RFFIT) in 27 of 353 Grenadian bats. Positives occurred in each of the 6 species sampled, with 40.5% prevalence in A. jamaicensis. In 11 of 86 Trinidadian bats of 4 species known to carry rabies, positive sera occurred only in A. jamaicensis (18.6%) and A. lituratus (18.1%). The potential use of the REFIT indetermining rabies activity is discussed.

Animals↗
PubMed1978

The basilar membrane of the bat, Pteronotus p. parnellii.

The basilar membrane of Pteronotus p. parnellii was studied by light and scanning electron microscopy in order to examine the relationship of membrane structure to the sharply tuned sense of hearing in this bat. The basilar membrane was found to differ from those of other mammals and other bats by showing virtually no change in width except at the extreme ends. Thickenings of the pars pectinata and pars tecta are well developed in Pteronotus; they show no sudden changes in their dimensions and in this way differ from the thickenings found in the European horseshoe bat whose sharply tuned sense of hearing seems at least partially dependent on sudden, marked changes in the structure of the basilar membrane. In Pteronotus the greater part of the basilar membrane, 7.5 mm or approximately 58%, lies within the enormous basal turn and within this turn there are steeply banked curves and one small 0.5-mm region where the membrane is straight. The straight portion is associated with a region of the cochlea where there is a marked change in the density of nerve fibers and where the stria vascularis, spiral ligament and fluid-filled spaces of the ear are enlarged.

Animals↗
PubMed1979

A morphometric study of the cochlea of the little brown bat (Myotis lucifugus).

A detailed morphometric study of the basilar membrane was made from serial sections and graphic reconstructions of the cochlea of three little brown bats. Four distinct morphometric changes were observed within the basilar membrane. First, between 0-1.4 mm from the basal end of the cochlea, there is a rapid increase in width and cross-sectional area of the basilar membrane. Secondly, between 1.4-2.5 mm, there is little change in width of the basilar membrane (its cross-sectional area is at its greatest in this region). Thirdly, between 2.7-3.1 mm, there is a sudden decrease in cross-sectional area concomitant with an increase in the width of the basilar membrane. Finally, between 3.1 mm and the apex, there is a gradual decrease in cross-sectional area concomitant with an increase in the width of the basilar membrane. The magnitudes of the cross-sectional areas of the scalae media and vestibuli decrease from base to apex, but this is not true for the scala tympani. The cross-sectional area of the scala tympani appears to decrease from the base to 0.7 mm, then it increases up to 1.4 mm, and then it decreases to the apex. These morphometric changes in the basilar membrane of the little brown bat are compared to those in other echolocating and non-echolocating mammals. The significance of these changes is discussed in relation to the range of hearing in the little brown bat.

Animals↗
PubMed1977

Viruses isolated from bats in Japan.

Virus isolation has been attempted from the blood, spleen, liver and kidneys of bats. Nine viruses (1.1 per cent) have been isolated so far from 838 bats collected in different places in Japan. Two of the isolates (TOK-1350 and TOK-1362) were isolated from Vespertilio supernas collected in Fukushima Prefecture. They killed suckling mice within 3-5 days after intracerebral inoculation. The remaining seven isolates were all filtrable through Millipore filters (0.22 micron) and were pathogenic for suckling mice but not adults. One of seven strains (KY-5) was ether resistant and another (TOK-292) was partially ether resistant and both were resistant to sodium deoxycholate (SDC); another (KY-663) was partially resistant to SDC. The sucrose acetone (SA) antigen of each new isolate did not show haemagglutination (HA) with goose red cells, even after protamine or ultrasonic treatment. Complement fixing (CF) activity was found in four of the seven strains. Both TOK-949 and VS-820 were collected at the same place and probably have the same CF activity. The remaining five strains are apparently different. Both YF-17D and Rio Bravo gave high HI titre with antisera against KY-5, TOK-949, TOK-1280, VS-820 and VeJ-822. They thus seemed to be flaviviruses although they were distinct from Japanese encephalitis virus (JEV) strains. From 1 to 10 per cent of bat sera contained antibody against JEV.

Animals↗
PubMed2026

Characterization and evolutionary history of novel SARS-CoV-2-related viruses in bats from Cambodia.

Circulating bat coronaviruses present a significant pandemic threat, yet our understanding of their genetic diversity and evolutionary dynamics remains limited. Over 3 years, we sampled 1,462 bats in Cambodia's Steung Treng province, identifying extensive and diverse coronaviruses co-circulation. Using metatranscriptomic and amplicon sequencing, we generated 33 complete sarbecovirus genomes sequences, revealing novel lineages that cluster into four distinct groups, each associated with different Rhinolophus bat species. Our analysis highlights rapid migration and recombination of sarbecovirus lineages over short distances and timescales. Of note, the receptor-binding domains of two novel viral groups exhibit high similarity to SARS-CoV-2, and pseudovirus assays confirmed the ability of this spike protein to mediate entry into cells expressing human ACE2, suggesting a potential zoonotic risk. The observed genetic diversity underscores the urgent need for continuous surveillance to identify high-risk animal-to-human interfaces and inform pandemic preparedness.

Animals↗
PubMed1977

Echolocation performance of the vampire bat (Desmodus rotundus).

The neotropical vampire bats (Desmodus rotundus) echolocate using ultrasonic pulses like those of the Latin American phyllostomatid bats. In this paper the orally produced echolocation sounds of Desmodus are analysed and the performance of the echolocation system is studied in two-choice training experiments on two vampire bats. Ability to detect objects is relatively limited; both animals were capable of discerning the presence of a 1 cm wide metal strip at a distance of 50 cm, but they failed with 0.5 cm wide strips. The ultrasonic pulses produced at a distance of 50 cm appear to sample an area with a diameter of 2.5 to 3.0 cm (i.e., the solid angle tested with each pulse is 3 degrees to 3 degrees 40' in extent).

Animals↗
PubMed1979

Perception of echo phase information in bat sonar.

Echolocating bats (Eptesicus fuscus) can detect changes as small as 500 nanoseconds in the arrival time of sonar echoes when these changes appear as jitter or alternations in arrival time from one echo to the next. The psychophysical function relating the bat's performance to the magnitude of the jitter corresponds to the half-wave rectified cross-correlation function between the emitted sonar signals and the echoes. The bat perceives the phase or period structure of the sounds, which cover the 25- to 100-kilohertz frequency range, as these are represented in the auditory system after peripheral transformation. The acoustic image of a sonar target is apparently derived from time-domain or periodicity information processing by the nervous system.

Animals↗
PubMed1979

Neural axis representing target range in the auditory cortex of the mustache bat.

In echolocating bats, the primary cue for determining distance to a target is the interval between an emitted orientation sound and its echo. Whereas frequency is represented by place in the bat cochlea, no anatomical location represents of primary range. Target range is coded by the time interval between grouped discharges of primary auditory neurons in response to both the emitted sound and its echo. In the frequency-modulated-signal processing area of the auditory cortex of the mustache bat (Pteronotus parnellii rubiginosus), neurons respond poorly or not at all to synthesized orientation sounds or echoes alone but respond vigorously to echoes following the emitted sound with a specific delay from targets at a specific range. These range-tuned neurons are systemically arranged along the rostrocaudal axis of the frequency-modulated-signal processing area according to the delays to which they best respond, and thus represent target range in terms of cortical organization. The frequency-modulated-signal processing area therefore shows odotopic representation.

Animals↗
PubMed1979

Harmonic-sensitive neurons in the auditory cortex of the mustache bat.

Human speech and animal sounds contain phonemes with prominent and meaningful harmonics. The biosonar signals of the mustache bat also contain up to four harmonics, and each consists of a long constant-frequency component followed by a short frequency-modulated component. Neurons have been found in a large cluster within auditory cortex of this bat whose responses are facilitated by combinations of two or more harmonically related tones. Moreover, the best frequencies for excitation of these neurons are closely associated with the constant-frequency components of the biosonar signals. The properties of these neurons make them well suited for identifying the signals produced by other echolocating mustache bats. They also show how meaningful components of sound are assembled by neural circuits in the central nervous system and suggest a method by which sounds with important harmonics (or formants) may be detected and recognized by the brain in other species, including humans.

Action Potentials↗
PubMed1978

Fine structure of the Kupffer cell in the bat, with special reference to the worm-like bodies.

The livers from normal bats captured in summer and autumn (active period) and in winter (hibernating period) were electron microscopically examined with reference to the worm-like bodies. 1) The worm-like bodies were numerous in bats captured in the active periods, while they were few in hibernating bats. The development of this body varied considerably from cell to cell. 2) The worm-like body seemed to develop from a short and straight tubular invagination of the plasma membrane, whereas the fully developed unit of the body comprised a twisted and complicatedly branching tubule extended in the cytoplasm, the end of which seemed to be retained as the orifice to the extracellular space. The contents of the tubule continuous with the cell coat showed faint transverse striation and a median dense line. A large worm-like body was presumably composed of a number of the units tangled complicatedly with each other, showing a large accumulation of abundant profiles of closely packed tubules. In some Kupffer cells a long tortuous tubule with a median dense line penetrated the cytoplasm transversely and communicated at both ends with two opposite surfaces facing the sinusoid. 3)The cytoplasmic area of the worm-like bodies was almost completely devoid of organelles; no communication between the worm-like bodies and other organelles was recognized. This finding suggested the resemblance of the area of the worm-like bodies to the ectoplasm. This assumption also was supported by frequent occurence of large coated vesicles along the worm-like bodies often communicating with them. 4)The worm-like bodies did not show any signs of enlargement even in Kupffer cells ingesting blood cells in their phagocytic vacuoles. Their profiles were found abutting on the phagosomes, but direct communication between both structures was not found. 5)It was proposed in this study that the worm-like bodies might possibly represent a membrane reservoir and contribute to the enlargement of the Kupffer cell surface.

Animals↗