Search

Diverse animal taxa are capable of rapidly modifying vocalizations to mitigate interference from environmental noise. Echolocating bats, for example, must frequently perform sonar tasks in the presence of interfering sounds. Numerous studies have documented sound production flexibility in echolocating bats; however, it remains unknown whether noise-induced vocal modifications (NIVMs) mitigate interference effects on echoes or calls. In this study, we leverage echo level compensation behavior of echolocating bats to answer this question. Using a microphone array, we recorded echolocation calls of Hipposideros pratti trained to approach and land on a perch in the laboratory under quiet and noise conditions. We found that H. pratti exhibited echo level compensation behavior during approaching flights, which depended critically on distance to the landing perch. Broadcast noise delayed and affected the rate of echo level compensation in H. pratti. Moreover, H. pratti increased vocalization amplitude, i.e., exhibited the Lombard effect, while also adjusting call duration and bandwidth with increasing noise levels. Quantitative analyses of the data show that H. pratti relies on echo feedback, not vocal feedback, to adjust signals in the presence of noise. These findings provide compelling evidence that NIVMs in echolocating animals and non-echolocating animals operate through different mechanisms.

Background Bats are remarkable in their dynamic control over body temperature, showing both hypothermia with torpor and hyperthermia during flight. Despite considerable research in understanding bats’ thermoregulation mechanisms, knowledge on the relationship between flight and body temperature in bats remains limited, possibly due to technological restraints. Results We used onboard dataloggers including a temperature sensor and an inertial sensor (accelerometers) and continuously recorded the flight behavior and skin temperature (Tsk) subcutaneously of a perch-hunting bat, Hipposideros armiger, both in the laboratory and in the field. We provide evidence that flight increases the body temperature of bats. The median of the maximum increase in the Tsk caused by flight bouts was 3.4 °C (between 1.9 and 5.3 °C for different individuals) in the laboratory. The maximum Tsk for the bats was narrowly centered around 40 °C (between 38.5 and 40.9 °C). Moreover, we found that the faster the Tsk rises, the greater the maximum increase in Tsk. Interestingly, bats can slow down the Tsk rises with intermittent fights, during which they perch after brief flight bouts to allow the body temperature to drop rapidly. Similar data were collected from field recordings in free-ranging bats. Conclusions We suggest that perch-hunting behavior observed in approximately 200 species of bats that results in intermittent flights may function as a thermoregulatory strategy, in addition to optimizing energy efficiency as demonstrated by previous studies.

Heavy metal pollution in the soil surrounding solid wastes from coking plants poses potential threats to human health and has attracted widespread attention. This study is the first to assess the spatial variability and risks of heavy metals in the soil surrounding solid waste from coking plants. The results showed that the concentrations of Cu, Ni, Pb, and Cd in the soil were much higher than the background value of the soil. Solid waste had a clear influence on the contents of Ni, Cd, Mn, Pb, and Cr in the soil. The ecological risk assessment of heavy metal pollution demonstrated that the pollution degree of Cu, Pb, and Cd was more serious than others, and the ecological risk of heavy metals was mainly caused by Cd in the soil. The human health risk assessment showed that adults and children near coking plants might face carcinogenic risk from exposure to Cr. This study can provide a theoretical basis for the prevention and management of soil heavy metal pollution surrounding solid waste in coking plants.

Fine audiovocal control is a hallmark of human speech production and depends on precisely coordinated muscle activity guided by sensory feedback. Little is known about shared audiovocal mechanisms between humans and other mammals. We hypothesized that real-time audiovocal control in bat echolocation uses the same computational principles as human speech. To test the prediction of this hypothesis, we applied state feedback control (SFC) theory to the analysis of call frequency adjustments in the echolocating bat, Hipposideros armiger . This model organism exhibits well-developed audiovocal control to sense its surroundings via echolocation. Our experimental paradigm was analogous to one implemented in human subjects. We measured the bats’ vocal responses to spectrally altered echolocation calls. Individual bats exhibited highly distinct patterns of vocal compensation to these altered calls. Our findings mirror typical observations of speech control in humans listening to spectrally altered speech. Using mathematical modeling, we determined that the same computational principles of SFC apply to bat echolocation and human speech, confirming the prediction of our hypothesis.

James Simmons’s early research on sonar ranging in echolocating bats generated two groundbreaking discoveries: (1) Bats compute object distance from the time delay between sonar calls and echoes, and they discriminate echo-delay differences in the microsecond range [Simmons, https://psycnet.apa.org/doi/10.1121/1.1913559 (1973)] and (2) A population of auditory neurons show facilitated and echo delay-tuned responses, a posited neural substrate of sonar ranging [Feng et al., https://10.1126/science.705350 (1978)]. These findings spawned decades of biosonar research around the world, and this talk will summarize three new findings on the mechanisms of sonar ranging in the big brown bat, Eptesicus fuscus. (1) Echo-delay tuned neurons in the midbrain of the free-flying bat show 3D spatial tuning to echoes from physical objects, and sonar-guided attention evokes sharper delay-dependent response areas and shifts to shorter echo delays. (2) Local field potential recordings from auditory midbrain neurons in the passively listening bat encode the time interval between call-echo pairs in the microsecond range, with accuracy dependent on signal duration and bandwidth. (3) A population of hippocampal CA1 neurons encodes the distance of sonar objects in bats as they track moving targets, and responses of hippocampal neurons depend on the production of sonar calls that yield echo returns.

The functional properties of the auditory midbrain, inferior colliculus (IC), plays a critical role in James Simmons’s SCAT model of target ranging by echolocation. This SCAT model is based solely on the big brown bat producing frequency-modulated (FM) sonar calls. By contrast, there has been very limited knowledge on how the auditory midbrain may encode target ranging information in bats that produce constant-frequency (CF) sonar calls. Here, we conducted single-unit recordings from the auditory midbrain of passively listening Hipposideros armiger using naturalistic echolocation sequences. We created echolocation sequences from recordings taken from individual bats swung on a moving pendulum that evokes Doppler shift compensation (DSC) of their sonar vocalizations. Our preliminary data revealed a population of IC neurons selectively responded to DSC information in the sequences. To our surprise, we did not find neurons that encode echo delays. Considering published data on FM bats, these results suggest that the functional role of auditory midbrain for echolocation may be distinct between FM bats and CF-FM bats.

Although James Simmons’s pioneering work on bats’ target ranging capability by echolocation has been widely acknowledged, his contributions to other fields of bat echolocation have often been underappreciated. For example, James Simmons was probably the first to observe that echolocating bats can employ remarkable vocal flexibilities to counter masking noise effects on target ranging [Simmons et al., https://doi.org/10.1121/1.1914154 (1974)], a research topic that has only gained popularity in the bioacoustics community in recent two decades or so. In this talk, we present the latest data on noise-induced vocal flexibility of five species of bats, including Hipposideros pratti and four Rhinolophids. All bats emit echolocation calls consisting of a constant frequency component and a frequency modulated component. We first show that both Rhinolophid and hipposiderid bats possess a highly developed vocal flexibility to counter noise interference. Then, with H. pratti we demonstrate that the expression of vocal flexibility by the same individual was affected by several factors, such as the behavioral context or task, and history of training, which were believed to mediate the noise-induced vocal flexibility of humans only. These results emphasize the value of the comparative approach in understanding the vocal production control of mammals.

James Simmons's previous study on automatic gain control in the big brown bat has suggested the contractions of middle-ear muscle and forward masking impairing hearing sensitivity during vocalization. The influence of vocal production can be extremely severe for bat species that produce constant-frequency (CF) sonar signals. However, perceptual hearing sensitivity and the underlying mechanisms in CF bats remain virtually unexplored. In this work, combing a 2-AFC psychophysical setup and an electrophysiological setup, we measured the hearing sensitivity of a CF bat, Hipposideros pratti, either in a passive listening (PL) task to detect pure tones, an active listening (AL) task to detect pure tones triggered by its vocalization, or a phantom Echo task. Behavioral data show that H. pratti had the best hearing sensitivity of approximately 0 dB SPL in the PL task, but nearly 40 dB worse in the Echo task. In the AL task, all bats gradually increased call frequency by 0.8 to 1.1 kHz to overcome self-generated auditory masking. Preliminary neurophysiological data indicate that the neural responses in the midbrain inferior colliculus can be highly plastic. Together, our data suggest that echolocating bats dynamically control the hearing sensitivity during vocalization in a complex manner.

The COVID-19 is caused by the SARS-CoV-2, which is extremely infectious. Numerous virologist suggestions and guidelines advised using P2/N95 masks, gloves, goggles, face-shields, and frocks or gowns as routine specific protective tools during airway management to protect healthcare personnel from infection (PPE). However, numerous imitation research has indicated that conventional PPE cannot adequately protect healthcare personnel. Since then, numerous firms and healthcare professionals have created their personal reformed devices 'aerosol containment devices' (ACD). Their usage has expanded throughout the world without being properly evaluated for usefulness, efficacy, or safety. The practice of 'ACD' has been shown to make tracheal intubation (TI) more problematic in several simulated tests. Furthermore, the device should limit the transmission of droplets from a patient; however, it might put healthcare personnel at danger of being exposed to greater levels of viral aerosols. Consequently, the existing state of information suggests that 'ACD' deprived of a vacuum mechanism can simply protect healthcare personnel against viral transmission to a limited extent. We search various databases for the literature with keywords 'COVID-19,' 'aerosol box,' 'aerosol contaminations,' and 'droplet contaminations.' The current review focused on the aerosol box from various perspectives, including their mechanism, optimum time of use, the spread of aerosol control, current gaps, and future perspective for bridging those gaps.

Global changes in response to human encroachment into natural habitats and carbon emissions are driving the biodiversity extinction crisis and increasing disease emergence risk. Host distributions are one critical component to identify areas at risk of viral spillover, and bats act as reservoirs of diverse viruses. We developed a reproducible ecological niche modelling pipeline for bat hosts of SARS-like viruses (subgenus Sarbecovirus ), given that several closely related viruses have been discovered and sarbecovirus–host interactions have gained attention since SARS-CoV-2 emergence. We assessed sampling biases and modelled current distributions of bats based on climate and landscape relationships and project future scenarios for host hotspots. The most important predictors of species distributions were temperature seasonality and cave availability. We identified concentrated host hotspots in Myanmar and projected range contractions for most species by 2100. Our projections indicate hotspots will shift east in Southeast Asia in locations greater than 2°C hotter in a fossil-fuelled development future. Hotspot shifts have implications for conservation and public health, as loss of population connectivity can lead to local extinctions, and remaining hotspots may concentrate near human populations.

Understanding the neural underpinnings of vocal-motor control in humans and other animals remains a major challenge in neurobiology. The Lombard effect - a rise in call amplitude in response to background noise - has been demonstrated in a wide range of vertebrates. Here, we review both behavioral and neurophysiological data and propose that the Lombard effect is driven by a subcortical neural network, which can be modulated by cortical processes. The proposed framework offers mechanistic explanations for two fundamental features of the Lombard effect: its widespread taxonomic distribution across the vertebrate phylogenetic tree and the widely observed variations in compensation magnitude. We highlight the Lombard effect as a model behavioral paradigm for unraveling some of the neural underpinnings of audiovocal integration.

Air pollution has been an important risk factor for female reproductive health. However, epidemiological evidence of ambient air pollution on the predictor for ovarian reserve (antral follicle count, AFC) is deficient. We aim to comprehensively evaluate the association of long-term exposure to ambient air pollution with AFC among women of reproductive age in Shanxi of north China. 600 women with spontaneous menstrual cycle, not using controlled ovarian stimulation, were enrolled in the retrospective study. Two distinct periods of antral follicle development were designed as exposure windows. Generalized linear model was employed to estimate the change of AFC associated with exposure of atmospheric pollutants (SO2, NO2, PM10, PM2.5, CO and O3). Stratification analysis based on age ( 5 years) along with two pollutants model were employed to further illustrate the association. We found every 10 μg/m3 increase in SO2 concentration level during the entire development stage of antral follicle was associated with a −0.01 change in AFC (95% confidence interval: −0.016, −0.002) adjusting for the confounders including age, BMI, parity and infertility diagnosis factors. The significant association of increased SO2 level with decreased AFC was particularly observed during the early transition from primary follicle to preantral follicle stage by 10 μg/m3 increase in SO2 exposure level with a −0.01 change (95% CI: -0.015, −0.002) in AFC. The negative association was pronounced among women aged ≥30 years old, and also significant in two pollutants model after adjusting the confounders. No significant associations between other air pollutants and AFC were observed. Our finding suggests that long-term exposure to air pollutant SO2 is associated with lower AFC, raising our concern that atmospheric SO2 exposure may have potential adverse impact on women ovarian reserve.

With >1 400 species, bats comprise the second-largest order of mammals and provide critical ecological services as insect consumers, pollinators, and seed dispersers. Yet, bats are frequently associated with infectious human diseases such as SARS, MERS, and Ebola. As early as the end of January 2020, several virological studies have suggested bats as a probable origin for SARS-CoV-2, the causative agent of COVID-19. How does the public view the role of bats in COVID-19? Here we report pilot data collected shortly after the outbreak of COVID-19 using two online surveys, combined with a conservation intervention experiment, primarily on people who are receiving or have received higher education in China. We found that 84% of the participants of an online survey (n = 13 589) have misunderstood the relationship between bats and COVID-19, which strengthened negative attitudes towards bats. Knowledge of bats, gender, and education level of the participants affected their attitudes towards bats. Participants who indicated a better knowledge of bats had a more positive attitude towards bats. The proportion of female participants who had negative attitudes towards bats was higher than that of male participants. Participants with a higher education level indicated a more positive attitude towards bats after the outbreak of COVID-19. A specially prepared bat conservation lecture improved peoples' knowledge of bats and the positive attitudes, but failed to correct the misconception that bats transmit SARS-CoV-2 to humans directly. We suggest that the way virologists frame the association of bats with diseases, the countless frequently inaccurate media coverages, and the natural perceptual bias of bats carrying and transmitting diseases to humans contributed to the misunderstandings. This probably led to a rise in the events of evicting bats from dwellings and structures by humans and the legislative proposal for culling disease-relevant wildlife in China. A better understanding of the relationship between disease, wildlife and human health could help guide the public and policymakers in an improved program for bat conservation.

Flexible vocal production control enables sound communication in both favorable and unfavorable conditions. The Lombard effect, which describes a rise in call amplitude with increasing ambient noise, is a widely exploited strategy by vertebrates to cope with interfering noise. In humans, the Lombard effect influences the lexical stress through differential amplitude modulation at a sub-call syllable level, which so far has not been documented in animals. Here, we bridge this knowledge gap with Hipposideros bats which produce echolocation calls consisting of two functionally well-defined units: the constant-frequency (CF) and frequency-modulated (FM) components. We show that ambient noise induced a strong, but differential, Lombard effect in the CF and FM components of the echolocation calls. We further report that the differential amplitude compensation occurred only in the spectrally overlapping noise conditions, suggesting a functional role in releasing masking. Lastly, we show that both species of bats exhibited a robust Lombard effect in the spectrally non-overlapping noise conditions, which contrast sharply with the existing evidence. Our data highlight echolocating bats as a potential mammalian model for understanding vocal production control.

Many species of bat emit acoustic signals and use information carried by echoes reflecting from nearby objects to navigate and forage. It is widely documented that echolocating bats adjust the features of sonar calls in response to echo feedback; however, it remains unknown whether audiovocal feedback contributes to sonar call design. Audiovocal feedback refers to the monitoring of one's own vocalizations during call production and has been intensively studied in nonecholocating animals. Audiovocal feedback not only is a necessary component of vocal learning but also guides the control of the spectro-temporal structure of vocalizations. Here, we show that audiovocal feedback is directly involved in the echolocating bat's control of sonar call features. As big brown bats tracked targets from a stationary position, we played acoustic jamming signals, simulating calls of another bat, timed to selectively perturb audiovocal feedback or echo feedback. We found that the bats exhibited the largest call-frequency adjustments when the jamming signals occurred during vocal production. By contrast, bats did not show sonar call-frequency adjustments when the jamming signals coincided with the arrival of target echoes. Furthermore, bats rapidly adapted sonar call design in the first vocalization following the jamming signal, revealing a response latency in the range of 66 to 94 ms. Thus, bats, like songbirds and humans, rely on audiovocal feedback to structure sonar signal design.

In many mammals, upward-sweeping frequency-modulated (FM) sounds (up-chirps) evoke larger auditory brainstem responses than downward-sweeping sounds (down-chirps). To determine if similar effects occur in FM echolocating bats, auditory evoked responses (AERs) in big brown bats in response to up-chirps and down-chirps at different chirp durations and levels were recorded. Even though down-chirps are the biologically relevant stimulus for big brown bats, up-chirps typically evoked larger peaks in the AER, but with some exceptions at the shortest chirp durations. The up-chirp duration that produced the largest AERs and the greatest differences between up-chirps and down-chirps varied between individual bats and stimulus levels. Cross-covariance analyses using the entire AER waveform confirmed that amplitudes were typically larger to up-chirps than down-chirps at supra-threshold levels, with optimal durations around 0.5–1 ms. Changes in response latencies with stimulus levels were consistent with previous estimates of amplitude-latency trading. Latencies tended to decrease with increasing up-chirp duration and increase with increasing down-chirp duration. The effects of chirp direction on AER waveforms are generally consistent with those seen in other mammals but with small differences in response patterns that may reflect specializations for FM echolocation.

Landmark-guided navigation is a common behavioral strategy for way-finding, yet prior studies have not examined how animals collect sensory information to discriminate landmark features. We investigated this question in animals that rely on active sensing to guide navigation. Four echolocating bats (Eptesicus fuscus) were trained to use an acoustic landmark to find and navigate through a net opening for a food reward. In experimental trials, an object serving as a landmark was placed adjacent to a net opening and an object serving as a distractor was placed next to a barrier (covered opening). The location of the opening, barrier and objects were moved between trials, but the spatial relationships between the landmark and opening, and between the distractor and barrier were maintained. In probe trials, the landmark was placed next to a barrier, while the distractor was placed next to the opening, to test whether the bats relied on the landmark to guide navigation. Vocal and flight behaviors were recorded with an array of ultrasound microphones and high-speed infrared motion-capture cameras. All bats successfully learned to use the landmark to guide navigation through the net opening. Probe trials yielded an increase in both the time to complete the task and the number of net crashes, confirming that the bats relied largely on the landmark to find the net opening. Further, landmark acoustic distinctiveness influenced performance in probe trials and sonar inspection behaviors. Analyses of the animals' vocal behaviors also revealed differences between call features of bats inspecting landmarks compared with distractors, suggesting increased sonar attention to objects used to guide navigation.

Echolocating bats must process temporal streams of sonar sounds to represent objects along the range axis. Neuronal echo-delay tuning, the putative mechanism of sonar ranging, has been characterized in the inferior colliculus (IC) of the mustached bat, an insectivorous species that produces echolocation calls consisting of constant frequency and frequency modulated (FM) components, but not in species that use FM signals alone. This raises questions about the mechanisms that give rise to echo-delay tuning in insectivorous bats that use different signal designs. To investigate whether stimulus context may account for species differences in echo-delay selectivity, we characterized single-unit responses in the IC of awake passively listening FM bats, Eptesicus fuscus, to broadcasts of natural sonar call-echo sequences, which contained dynamic changes in signal duration, interval, spectrotemporal structure, and echo-delay. In E. fuscus, neural selectivity to call-echo delay emerges in a population of IC neurons when stimulated with call-echo pairs presented at intervals mimicking those in a natural sonar sequence. To determine whether echo-delay selectivity also depends on the spectrotemporal features of individual sounds within natural sonar sequences, we studied responses to computer-generated echolocation signals that controlled for call interval, duration, bandwidth, sweep rate, and echo-delay. A subpopulation of IC neurons responded selectively to the combination of the spectrotemporal structure of natural call-echo pairs and their temporal patterning within a dynamic sonar sequence. These new findings suggest that the FM bat’s fine control over biosonar signal parameters may modulate IC neuronal selectivity to the dimension of echo-delay. NEW & NOTEWORTHY Echolocating bats perform precise auditory temporal computations to estimate their distance to objects. Here, we report that response selectivity of neurons in the inferior colliculus of a frequency modulated bat to call-echo delay, or target range tuning, depends on the temporal patterning and spectrotemporal features of sound elements in a natural echolocation sequence. We suggest that echo responses to objects at different distances are gated by the bat’s active control over the spectrotemporal patterning of its sonar emissions.

Temporal analysis of sound is fundamental to auditory processing throughout the animal kingdom. Echolocating bats are powerful models for investigating the underlying mechanisms of auditory temporal processing, as they show microsecond precision in discriminating the timing of acoustic events. However, the neural basis for microsecond auditory discrimination in bats has eluded researchers for decades. Combining extracellular recordings in the midbrain inferior colliculus (IC) and mathematical modeling, we show that microsecond precision in registering stimulus events emerges from synchronous neural firing, revealed through low-latency variability of stimulus-evoked extracellular field potentials (EFPs, 200–600 Hz). The temporal precision of the EFP increases with the number of neurons firing in synchrony. Moreover, there is a functional relationship between the temporal precision of the EFP and the spectrotemporal features of the echolocation calls. In addition, EFP can measure the time difference of simulated echolocation call–echo pairs with microsecond precision. We propose that synchronous firing of populations of neurons operates in diverse species to support temporal analysis for auditory localization and complex sound processing., Author summary We routinely rely on a stopwatch to precisely measure the time it takes for an athlete to reach the finish line. Without the assistance of such a timing device, our measurement of elapsed time becomes imprecise. By contrast, some animals, such as echolocating bats, naturally perform timing tasks with remarkable precision. Behavioral research has shown that echolocating bats can estimate the elapsed time between sonar cries and echo returns with a precision in the range of microseconds. However, the neural basis for such microsecond precision has remained a puzzle to scientists. Combining extracellular recordings in the bat’s inferior colliculus (IC)—a midbrain nucleus of the auditory pathway—and mathematical modeling, we show that microsecond precision in registering stimulus events emerges from synchronous neural firing. Our recordings revealed a low-latency variability of stimulus-evoked extracellular field potentials (EFPs), which, according to our mathematical modeling, was determined by the number of firing neurons and their synchrony. Moreover, the acoustic features of echolocation calls, such as signal duration and bandwidth, which the bat dynamically modulates during prey capture, also modulate the precision of EFPs. These findings have broad implications for understanding temporal analysis of acoustic signals in a wide range of auditory behaviors across the animal kingdom.

Sensing is fundamental to the control of movement: From grasping objects to speech production, sensing guides action. So far, most of our knowledge about sensorimotor integration comes from visually guided reaching and oculomotor integration, in which the time course and trajectories of movements can be measured at a high temporal resolution. By contrast, production of vocalizations by humans and animals involves complex and variable actions, and each syllable often lasts a few hundreds of milliseconds, making it difficult to infer underlying neural processes. Here, we measured and modeled the transfer of sensory information into motor commands for vocal amplitude control in response to background noise, also known as the Lombard effect. We exploited the brief vocalizations of echolocating bats to trace the time course of the Lombard effect on a millisecond time scale. Empirical studies revealed that the Lombard effect features a response latency of a mere 30 ms and provided the foundation for the quantitative audiomotor model of the Lombard effect. We show that the Lombard effect operates by continuously integrating the sound pressure level of background noise through temporal summation to guide the extremely rapid vocal-motor adjustments. These findings can now be extended to models and measures of audiomotor integration in other animals, including humans.

Ecologists and evolutionary biologists have a long-standing interest in the patterns and causes of geographical variation in animals’ acoustic signals. Nonetheless, the processes driving acoustic divergence are still poorly understood. Here, we studied the geographical variation in echolocation vocalizations (commonly referred to as echolocation ‘pulses’ given their short duration and relatively stereotypic nature, and to contrast them from the communicative vocalizations or ‘calls’) of a widespread bat species Hipposideros armiger in south China, and assessed whether the acoustic divergence was driven by either ecological selection, or cultural or genetic drift. Our results revealed that the peak frequency of echolocation pulses varied significantly across populations sampled, with the maximum variation of about 6 kHz. The peak frequency clustered into three groups: eastern and western China, Hainan and southern Yunnan. The population differences in echolocation pulses were not significantly related to the variation in climatic (mean annual temperature, mean annual relative humidity, and mean annual precipitable water) or genetic (genetic distance) factors, but significantly related to morphological (forearm length) variation which was correlated with mean annual temperature. Moreover, the acoustic differences were significantly correlated with geographical and latitudinal distance after controlling for ‘morphological distance’. Thus, neither direct ecological selection nor genetic drift contributed to the acoustic divergence observed in H. armiger. Instead, we propose that the action of both indirect ecological selection (i.e. selection on body size) as well as cultural drift promote, in part, divergence in echolocation vocalizations of individuals within geographically distributed populations.

Subterranean environments are essential for the survival of many bat species and other cave fauna but these places are subject to increasing human disturbance. To examine the significance of subterranean habitats for the conservation of bats in China we surveyed bat species in 225 underground sites during 2003–2011. Our results show that 77% of bat species in China, including 30 nationally Endangered or Vulnerable species and nine endemic species, roost in caves and other subterranean habitats. The number of species in occupied roosts was 1–15. Almost 90% of the roosts surveyed contained signs of human disturbance, most of which was from recreational activities. One hundred and twenty-one roosts merit special concern because they harbour ≥ 6 species or > 1,000 individuals, or species of special concern (threatened or endemic species). Generally, larger roosts support more species and a greater abundance of bats than smaller roosts but there is no direct correlation between the presence of species of special concern and roost size. Disused tourist caves have significantly more bat species than other types of roosts. Our data demonstrate that roost disturbance by recreational activities has pronounced detrimental effects on the number of bat species and the presence of species of special concern. We discuss the social, economic and political issues that could adversely affect bat conservation in caves in China, and we recommend that protection of subterranean habitats should be a high priority for bat conservation.

ObjectiveTo investigate the correlation between periostin and SNCG and esophageal cancer invasion, infiltration and apoptosis.MethodsA total of 78 cases esophageal surgical resection specimens were collected, expression of periostin and SNCG in esophageal cancer were detected. Effect of periostin and SNCG in esophageal carcinoma invasion and infiltration was analyzed.ResultsThe upregulated rate of periostin had significant difference in esophageal cancer tissues (39.74%), adjacent tissues (17.86%) and normal tissues (0.00%); The positive expression rates of SNCG had significant difference in esophageal cancer tissues (61.54%), adjacent tissues (32.14%) and normal tissues (1.96%); The upregulated rate of periostin had a significant correlation with lymph node metastasis, adventitia invasion, TNM stage; The positive expression rates of SNCG had a significant correlation with differentiation degree, lymph node metastasis, adventitia invasion, TNM stage; Apoptosis index of the positive of expression of SNCG of esophageal cancer tissue (4.541±2.267) was significantly lower than that of the negative expression (7.316±2.582) (P

X-ray cross-complementing group 6 (XRCC6) plays an important role in the DNA double-strand breaks repair and the maintenance of genomic integrity. XRCC6 C1310G polymorphism may be involved in the development of cancer through increasing genomic damages. However, studies investigating the relationship between XRCC6 C1310G polymorphism and cancer risk yielded contradictory results. To shed some light on these inconsistent findings, a meta-analysis was performed to clarify the effect of XRCC6 C1310G polymorphism on the susceptibility of cancer. A systemic literature search of PubMed, EMBASE, and China National Knowledge Infrastructure databases was conducted from their inception to September 26, 2012. The association between XRCC6 C1310G and cancer risk was assessed by the pooled odds ratio (OR) with 95 % confidence intervals (95 % CI) calculated by meta-analysis. A total of 15 eligible studies (4,642 cancer cases and 6,059 controls) were identified. Overall, there was obvious evidence for an association between XRCC6 C1310G polymorphism and increased risk of cancer under two genetic comparisons (GG vs. CC: fixed-effect OR 1.35, 95 % CI 1.10-1.66, I (2) = 17.0 %; GG vs. CG/CC: fixed-effect OR 1.25, 95 % CI 1.02-1.53, I (2) = 0.0 %). Subgroup analysis indicated that the association was significant in Asians (G vs. C: random-effect OR 1.13, 95 % CI 1.01-1.26, I (2) = 51.3 %; GG vs. CC: fixed-effect OR 1.43, 95 % CI 1.14-1.81, I (2) = 0.0 %; GG vs. CG/CC: fixed-effect OR 1.37, 95 % CI 1.09-1.72, I (2) = 0.0 %), but not in Europeans. Data from the current meta-analysis support the existence of an association between XRCC6 C1310G polymorphism and cancer risk in Asians. Studies with larger sample size are needed to further evaluate the influence of XRCC6 C1310G polymorphism on susceptibility of various cancers.

Auditory feedback plays an important role in vocal learning and, more generally, in fine-tuning the acoustic features of communication signals. So far, only a few studies have assessed the developmental onset of auditory feedback. The Lombard effect, a well-studied audio-vocal phenomenon, refers to an increase in vocal loudness of a subject in response to an increase in background noise. Here, we studied the time course of the Lombard effect in developing bats, Phyllostomus discolor. We show that infant bats produced louder vocalizations in noise than in silence at an age of only two weeks. In contrast, the infant bats' morphology and vocalizations changed gradually until two months of age. Furthermore, we found that the Lombard magnitude, i.e. how much the bats increased their vocal loudness in noise relative to silence, correlated positively with the age of the infant bats. We conclude that the Lombard effect features an early developmental origin, indicating a fast maturation of the underlying neural circuits for audio-vocal feedback.

Diagram of phenotyping husk traits. (A) husk number; (B) husk length; (C) husk width; (D) husk thickness.. (PPTX 346 kb)

Relative expression pattern of 10 selective genes in husk versus other tissues verified using RT-qPCR . The expression in each tissue was first normalized using the UBQ1 (GRMZM2G409726). Y-axis: the relative expression of each gene in husk relative to other tissues as indicated (log2 scale). Data is shown as the mean Âą SD of three independent experiments. (PPTX 71 kb)

Many animal species adjust the spectral composition of their acoustic signals to variable environments. However, the physiological foundation of such spectral plasticity is often unclear. The source-filter theory of sound production, initially established for human speech, applies to vocalizations in birds and mammals. According to this theory, adjusting the spectral structure of vocalizations could be achieved by modifying either the laryngeal/syringeal source signal or the vocal tract which filters the source signal. Here we show that in Pale spear-nosed bats, spectral plasticity induced by moderate level background noise is dominated by the vocal tract rather than the laryngeal source signal. Specifically, we found that with increasing background noise levels, bats consistently decreased the spectral centroid of their echolocation calls up to 3.2 kHz, together with other spectral parameters. In contrast, noise-induced changes in fundamental frequency were small (maximally 0.1 kHz) and were inconsistent across individuals. Changes in spectral centroid did not correlate with changes in fundamental frequency, whereas correlated negatively with changes in call amplitude. Furthermore, while the bats consistently increased the call amplitude with increasing noise levels (the Lombard effect), increases in call amplitude typically did not lead to increases in fundamental frequency. In summary, our results suggest that at least to a certain degree echolocating bats are capable of adjusting call amplitude, fundament frequency, and spectral parameters independently.

GWAS-derived Manhattan plots showing significant P-values associated with husk traits using GLM. Each dot represents an SNP. The horizontal dashed blue line represents the Bonferroni-corrected significant threshold 5.2Ă 10-7. (A) HN; (B) HL; (C) HW; (D) HT. (PPTX 163 kb)

The investigation of mechanism of species coexistence promotes understanding of the mechanistic processes behind community ecology and ecosystem functions. Niche theory declares that species coexistence within a community must partition the resources of their environment. Two sympatric and morphologically similar bat species, Rhinolophus affinis and Rhinolophus pearsoni, provided a unique opportunity to test the causal mechanism of coexistence. Previous study showed that their coexistence was promoted not by the trophic and spatial niche differentiation but the relatively high abundance of prey resources, which was not in accord with the prediction of niche theory. Here, therefore, we reanalyzed the dietary composition by fecal analysis and surveyed the feeding time of both species. Our results showed that R. affinis and R. pearsoni hunt mainly mostly on Coleoptera and Lepidoptera, and there was a very high overlap (0.84) of trophic niche between the two species. However, significant difference in the duration of the activity period between both species was detected, which illustrated that temporal partitioning of prey resource use facilitated their coexistence. Additionally, our work highlighted the importance of integration of the traditional methods and next-generation sequencing methods for identifying dietary composition of carnivores, and suggested that ongoing studies of species coexistence must consider simultaneously multiple niche axes.

RNA-binding proteins (RBPs) play essential roles in RNA metabolism, regulating RNA splicing, transport, surveillance, decay and translation. The aberrant expression of RBPs leads to gene expression alteration and frequently causes various diseases, such as cancer. In this study, we are the first to provide evidence that hMex-3A, a RBP that belongs to the human Mex-3 family with two K-homology RNA-binding domains, is involved in the regulation of tumorigenesis. We show that the silencing of hMex-3A by small interference RNA effectively inhibits cell proliferation in SNU-16 and AGS gastric cancer cells. Flow cytometry analysis confirmed this effect on SNU-16 cell growth and indicated that hMex-3A may function in the G1/M phase. Notably, hMex-3A knockdown also reduced the colony formation ability of SNU-16 and AGS cells in soft agar, implying that hMex-3A is required for cell transformation. Furthermore, the hMex-3A knockdown markedly affected the migratory ability of BCG-823 cells by transwell chamber and wound healing assays. Clinical relevance analysis using 22 paired gastric cancer specimens by quantitative real-time PCR showed that hMex-3A was significantly upregulated (63.6%) in cancer tissues compared with matched adjacent non-cancerous tissues. Taken together, these results suggest that hMex-3A functions as an oncogene candidate in the development and metastasis of gastric cancer; thus it may serve as a potential target for the therapy of tumors.

Short-term adjustments of signal characteristics allow animals to maintain reliable communication in noise. Noise-dependent vocal plasticity often involves simultaneous changes in multiple parameters. Here, we quantified for the first time the relative contributions of signal amplitude, duration and redundancy for improving signal detectability in noise. To this end, we used a combination of behavioural experiments on pale spear-nosed bats (Phyllostomus discolor) and signal detection models. In response to increasing noise levels, all bats raised the amplitude of their echolocation calls by 1.8–7.9 dB (the Lombard effect). Bats also increased signal duration by 13%–85%, corresponding to an increase in detectability of 1.0–5.3 dB. Finally, in some noise conditions, bats increased signal redundancy by producing more call groups. Assuming optimal cognitive integration, this could result in a further detectability improvement by up to 4 dB. Our data show that while the main improvement in signal detectability was due to the Lombard effect, increasing signal duration and redundancy can also contribute markedly to improving signal detectability. Overall, our findings demonstrate that the observed adjustments of signal parameters in noise are matched to how these parameters are processed in the receiver’s sensory system, thereby facilitating signal transmission in fluctuating environments.

Poor knowledge of the intraspecific variability in echolocation calls is recognized as an important limiting factor for the accurate acoustic identification of bats. We studied the echolocation behaviors of an ecologically poorly known bat species, Myotis macrodactylus, while they were commuting in three types of habitats differing significantly in the amount of background clutter, as well as searching for prey above the water surface in a river. Results showed that M. macrodactylus altered their echolocation call structure in the same way during commuting as foraging bats do in relation to the changing level of clutter. With increasing level of clutter, M. macrodactylus generally produced echolocation calls with higher start, end, and peak frequencies; wider bandwidth; and shorter pulse duration. Compared to commuting, bats emitted significantly lower frequency calls with narrower bandwidth while searching for prey. Discriminant function analysis indicated that 79.8% of the calls from the three commuting habitats were correctly grouped, and 87% of the calls were correctly classified to the commuting and foraging contexts. Our finding has implications for those who would identify species by their calls.