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Although cell culture systems for hepatitis E virus (HEV) have been established by using cell lines such as PLC/PRF/5 and A549, small-animal models for this virus are limited. Since Mongolia gerbils are susceptible to genotype 1, 3 and 4 HEV (HEV-1, HEV-3 and HEV4), we intraperitoneally inoculated Mongolia gerbils with HEV-5, HEV-7, HEV-8, rabbit HEV or rat HEV in addition to the above three genotypes to investigate the infectivity and to assess whether Mongolia gerbil is an appropriate animal model for HEV infection. The results indicated that (i) HEV-5 and rat HEV were effectively replicated in the Mongolia gerbils in the same manner as HEV-4: large amounts of the viral RNA were detected in the feces and livers, and high titers of the serum anti-HEV IgG antibodies were induced in all animals. The feces were shown to contain HEV that is infectious to naïve gerbils. Furthermore, HEV-4, HEV-5 and rat HEV were successfully transmitted to the gerbils by oral inoculation. (ii) Although the viral RNA and serum anti-HEV IgG antibodies were detected in all animals inoculated with HEV-1 and HEV-8, both titers were low. The viral RNA was detected in the feces collected from two of three HEV-3-inoculated, and one of three HEV-7-inoculated gerbils, but the titers were low. The serum antibody titers were also low. The viruses excreted into the feces of HEV-1-, HEV-3-, HEV-7- and HEV-8-inoculated gerbils failed to infect naïve Mongolia gerbils. (iii) No infection sign was observed in the rabbit HEV-inoculated gerbils. These results demonstrated that Mongolia gerbils are broadly susceptible to HEV, and their degree of sensitivity was dependent on the genotype. Mongolia gerbils were observed to be susceptible to not only HEVs belonging to HEV-A but also to rat HEV belonging to HEV-C1, and thus Mongolia gerbil could be useful as a small-animal model for cross-protection experiments between HEV-A and HEV-C1. Mongolia gerbils may also be useful for the evaluation of the efficacy of vaccines against HEV.

In nature, animal vocalizations can provide crucial information about identity, including kinship and hierarchy. However, lab-based vocal behavior is typically studied during brief interactions between animals with no prior social relationship, and under environmental conditions with limited ethological relevance. Here, we address this gap by establishing long-term acoustic recordings from Mongolian gerbil families, a core social group that uses an array of sonic and ultrasonic vocalizations. Three separate gerbil families were transferred to an enlarged environment and continuous 20-day audio recordings were obtained. Using a variational autoencoder (VAE) to quantify 583,237 vocalizations, we show that gerbils exhibit a more elaborate vocal repertoire than has been previously reported and that vocal repertoire usage differs significantly by family. By performing gaussian mixture model clustering on the VAE latent space, we show that families preferentially use characteristic sets of vocal clusters and that these usage preferences remain stable over weeks. Furthermore, gerbils displayed family-specific transitions between vocal clusters. Since gerbils live naturally as extended families in complex underground burrows that are adjacent to other families, these results suggest the presence of a vocal dialect which could be exploited by animals to represent kinship. These findings position the Mongolian gerbil as a compelling animal model to study the neural basis of vocal communication and demonstrates the potential for using unsupervised machine learning with uninterrupted acoustic recordings to gain insights into naturalistic animal behavior. Every time you speak, the sounds coming out of your mouth may carry more meaning that you may have intended; they may reveal, for example, which country, city or even neighborhood you may be coming from. Indeed, the vocal patterns that humans use to communicate differ from one population to the next, creating an array of languages, dialects and accents. Such diversity has also been identified in various social species across the animal kingdom. Naked mole rats, for instance, which live underground in complex societies, exhibit different ‘dialects’ depending on their group of origin. Yet studying the vocal patterns of animals has remained difficult, especially for species inhabiting burrows or other environments difficult to access. Aiming to bypass these limitations, Peterson et al. adopted a ‘naturalistic’ approach that allowed them to capture the vocal calls of three families of Mongolian gerbils living undisturbed in enclosures that mimic features of their natural environment. These animals spend their lives underground in tight-knit families, with multiple groups often being in close proximity. Researchers have speculated that individuals may rely on vocal cues to identify whether they are part of the same colony, as they are often too far from each other to rely on sight or smell. Over half a million vocalizations obtained continuously through the course of 20 days were analyzed using an artificial intelligence technique known as unsupervised machine learning. The analyses helped add new types of calls to the gerbil vocal repertoire, but also highlighted its complexity. In particular, they revealed that the animals could combine individual vocal elements into complex sequences. More importantly, this approach showed that gerbil families have vocal dialects that are stable across weeks, with each group displaying a preference for certain call types (i.e. words) and certain sequential patterns (i.e. phrases). These findings demonstrate the benefits of the approach developed by Peterson et al. for the study of animal vocalizations. Going forward, they also suggest that the Mongolian gerbil could be used as an animal model to study the neural basis of vocal communication.

Rodent activity is an important factor that affects the growth and development of Haloxylon ammodendron. Studying the effect of rodent disturbance on plant ecological stoichiometric ratios helps evaluate the mechanism by which rodent disturbance affects plant growth and development. In this study, H. ammodendron, a dominant plant, and the gerbil, a typical rodent in the Gurbantunggut Desert, were selected as research objects. By measuring the biomass, root soil , and C: N: P ecostoichiometric ratios of the assimilated branches of H. ammodendron at different growth phases, the impact of great gerbil disturbance on the biomass, ecostoichiometric ratios, and nutrient uptake and use of H. ammodendron were investigated at different growth stages. The results showed that the gerbil disturbance increased the biomass of the aboveground part of the adult H. ammodendron. Gerbil disturbance also increased the soil N/P around the roots during the growth stage and the assimilation branch when the plants were middle-aged. In addition, this disturbance decreased the C/N value. The photosynthetic nitrogen use efficiency (PNUE) and photosynthetic phosphorus use efficiency (PPUE) of H.ammodendron during various growth periods decreased, and the absorption of total nitrogen (TN) in the soil decreased. However, soil total potassium (TK) absorption increased. The soil TN absorption capacity was weakened by gerbil disturbance. Meanwhile, the TK absorption capacity was enhanced, and the biomass of adult H. ammodendron increased. PNUE and PPUE of H. ammodendron were decreased by gerbil interference. In this study, the influence of gerbil disturbance on nutrient absorption by H. ammodendron and use of H. ammodendron was determined. This has provided a baseline for further studies on the coexistence mechanisms of gerbils and H. ammodendron.

Transient ischemia in the whole brain leads to neuronal loss/death in vulnerable brain regions. The striatum, neocortex and hippocampus selectively loose specific neurons after transient ischemia. Just 5 minutes of transient ischemia can cause pyramidal neuronal death in the hippocampal cornu ammonis (CA) 1 field at 4 days after transient ischemia. In this study, we investigated the effects of 5-minute (mild), 15-minute (severe), and 20-minute (lethal) transient ischemia by bilateral common carotid artery occlusion (BCCAO) on behavioral change and neuronal death and gliosis (astrocytosis and microgliosis) in gerbil hippocampal subregions (CA1-3 region and dentate gyrus). We performed spontaneous motor activity test to evaluate gerbil locomotor activity, cresyl violet staining to detect cellular distribution, neuronal nuclei immunohistochemistry to detect neuronal distribution, and Fluoro-Jade B histofluorescence to evaluate neuronal death. We also conducted immunohistochemical staining for glial fibrillary acidic protein and ionized calcium-binding adapter molecule 1 (Iba1) to evaluate astrocytosis and microgliosis, respectively. Animals subjected to 20-minute BCCAO died in at least 2 days. BCCAO for 15 minutes led to pyramidal cell death in hippocampal CA1-3 region 2 days later and granule cell death in hippocampal dentate gyrus 5 days later. Similar results were not found in animals subjected to 5-minute BCCAO. Gliosis was much more rapidly and severely progressed in animals subjected to 15-minute BCCAO than in those subjected to 5-minute BCCAO. Our results indicate that neuronal loss in the hippocampal formation following transient ischemia is significantly different according to regions and severity of transient ischemia. The experimental protocol was approved by Institutional Animal Care and Use Committee (AICUC) of Kangwon National University (approval No. KW-180124-1) on May 22, 2018.

Onchocerciasis, the second leading infectious cause of blindness, afflicts approximately 21 million people globally. Its control is limited to the use of the microfilaricidal drugs, ivermectin and moxidectin. Both drugs are unable to kill the adult worms which can survive for up to 15 years in patients, justifying the urgent need for potent and novel macrofilaricides that kill adult worms. The development of such drugs has been hindered by the lack of an appropriate small laboratory animal model to evaluate potential drug candidates in vivo. This study assessed the survival of O. ochengi female worms and their embryos over time in two laboratory rodents: gerbils and hamsters and tested using “proof-of-concept” studies, whether known macrofilaricidal drugs can kill these worms. Animals were surgically implanted with mechanical or collagenase-liberated O. ochengi worm masses, and necropsied at various time points to test for survival. Recovered worm masses were assessed for viability by biochemical analysis (MTT/formazan assay) or fecundity (embryogram). Flubendazole (FBZ) administered at 20 mg/kg body weight was used to validate both rodent models. By day 26 post-implantation of 15 worm masses, a median of 7.00 (4.00–10.00) was recovered from hamsters, and 2.50 (2.00–4.00) from gerbils. Worm masses recovered from gerbils were mostly disintegrated or fragmented, with significantly higher fragmentation observed with collagenase-liberated worm masses. FBZ had no significant effect on the number of worm masses recovered, but enhanced embryo degradation in gerbils and reduced worm mass viability in hamsters. This exploratory study has revealed the gerbil and hamster as permissible rodents to adult female worms of O. ochengi . The hamsters appeared to maintain the worms longer, compared to gerbils.

Outer hair cells (OHCs) in the mammalian ear exhibit electromotility, electrically driven somatic length changes that are thought to mechanically amplify sound-evoked vibrations. For this amplification to work, OHCs must respond to sounds on a cycle-by-cycle basis even at frequencies that exceed the low-pass corner frequency of their cell membranes. Using in vivo optical vibrometry we tested this theory by measuring sound-evoked motility in the 13–25 kHz region of the gerbil cochlea. OHC vibrations were strongly rectified, and motility exhibited first-order low-pass characteristics with corner frequencies around 3 kHz– more than 2.5 octaves below the frequencies the OHCs are expected to amplify. These observations lead us to suggest that the OHCs operate more like the envelope detectors in a classical gain-control scheme than like high-frequency sound amplifiers. These findings call for a fundamental reconsideration of the role of the OHCs in cochlear function and the causes of cochlear hearing loss. Our ears give us our sense of hearing. Their job is to collect sounds and pass this information on to the brain. Hair cells, a special group of cells in the ear, are responsible for detecting sound vibrations and turning them into the electrical signals that our brains can understand. The ear contains two populations of hair cells: inner hair cells that send signals to the brain, and outer hair cells that act as a protective ‘buffer’ by modulating sound vibrations entering the innermost part of the ear. When outer hair cells are damaged, the vibrations picked up by inner hair cells are much smaller than in a healthy ear. This has led to the idea that outer hair cells actively amplify sounds before passing them on. That is, outer hair cells simultaneously act like microphones (by receiving sound from the environment) and loudspeakers (by re-emitting magnified vibrations). One problem with this amplifier theory is that it cannot explain how some animals are able to hear extremely high-pitched sounds. If the theory is true, outer hair cells should be able to re-emit ultrasonic vibrations. However, some observations suggest that they may not vibrate fast enough to do so. To test the amplifier theory, Vavakou et al. measured how outer hair cells in the ear of Mongolian gerbils responded to different sounds. This revealed that the motion of these cells could keep up with moderately high sounds (around the upper end of a piano’s range), but were too sluggish to amplify ultrasound despite gerbils having good ultrasonic hearing. Further experiments showed that instead of acting like amplifiers, outer hair cells seem to monitor the loudness of sound and adjust the level accordingly before passing the vibrations on to the inner hair cells. These results shed new light on how outer hair cells help our ears work. Since damage to these cells can cause hearing loss, understanding how they work could one day guide new methods of protecting or even restoring hearing in vulnerable patients.

Climate change combined with human activities has altered the spatial and temporal patterns of summer extreme heat in the Mu Us Desert. To determine how those rodents living in the desert respond to increased extreme heat in summer, in July 2022, during the hottest month, we examined the rodent species, vegetation coverage, and small-scale heterogeneity in ambient temperature in the southeastern Mu Us Desert. The results showed that Meriones meridianus, Meriones unguiculatus, and Cricetulus longicaudatus were found in the study area, where the vegetation coverage is 33.5–40.8%. Moreover, the maximum temperature of the desert surface was 61.8 °C. The maximum air temperature at 5 cm above the desert surface was 41.3 °C. The maximum temperature in the burrow at a depth of 15 cm was 31 °C. M. unguiculatus might experience 4–9.3 h of heat stress in a day when exposed outside the burrow, whereas M. meridianus would experience 8.5–10.8 h of heat stress. Yet, inside the burrow, both species were barely exposed to heat stress. In conclusion, adjustments in behavioral patterns can be the main way that rodents in the Mu Us Desert adapt to the extreme heat in the summer.

Background Rodents play an important role in the life cycle of ixodid and argasid ticks, particularly as hosts of larvae and nymphs. The great gerbil ( Rhombomys opimus ), the preferred prey item of several carnivores (e.g. the red fox and marbled polecat), is the dominant rodent species in the Gurbantunggut Desert in northwestern China. The aim of this study was to investigate tick species associated with different hosts in the habitat of great gerbils, including wildlife and livestock. Methods During 2018–2023, ticks were removed from 326 great gerbils, two red foxes ( Vulpes vulpes ), three marbled polecats ( Vormela peregusna ), 35 pastured sheep ( Ovis aries ), and one long-eared desert hedgehog ( Hemiechinus auritus ) in the Gurbantunggut Desert. Ticks were identified according to standard morphological keys. Then, they were further analyzed by molecular and phylogenic methods based on two mitochondrial markers, 16S rDNA and cytochrome c oxidase subunit I ( COI ) genes. Results A total of 889 ticks were collected, representing five species. These included Hyalomma asiaticum ( n  = 425: 24 larvae, 79 nymphs and 322 adults), Rhipicephalus turanicus ( n  = 153: 2 nymphs and 151 adults), Haemaphysalis erinacei ( n  = 298: 4 larvae, 7 nymphs and 287 adults), Ixodes acuminatus ( n  = 7: 4 nymphs and 3 adults) and Ornithodoros tartakovskyi (6 adults). Based on COI sequences, molecular and phylogenetic analyses showed that (i) I . acuminatus from great gerbils and marbled polecats clustered with I . acuminatus reported from Europe; (ii) O. tartakovskyi found in northwestern China belonged to an independent clade; (iii) Hy . asiaticum , R . turanicus and Ha . erinacei had 100% sequence identities to conspecific ticks sampled previously in China. Conclusions The great gerbil is an important host for the developmental stages of I . acuminatus , O . tartakovskyi , Ha . erinacei , Hy . asiaticum and R . turanicus , thus supporting the life cycle of several tick species which, as adults, parasitize predators (red fox and marble polecat) as well as pastured sheep and hedgehogs in the Gurbantunggut Desert. Ixodes acuminatus and O . tartakovskyi were found for the first time on great gerbil and marbled polecat, respectively. Graphical Abstract

Abstract The present review provides a compilation of the published data on the ecology and social behavior of tamarisk gerbils. Both field studies and direct observations under semi-natural conditions provide evidence that the tamarisk gerbil is a nocturnal herbivorous rodent that lives in highly seasonal habitats and displays seasonal fluctuations in reproduction and spatial organization. A typical feature of the tamarisk gerbils’ spatial organization is higher mobility of males during the breeding season (as compared with the nonbreeding period) and formation of temporary aggregations of males competing for access to receptive females; the composition of these aggregations was variable and depended on the reproductive condition of the females. Females tend to occupy exclusive home ranges irrespective of their reproductive condition. The mating system of the species can be defined as scramble competition polygyny with some features of polygynandry and promiscuity. The tamarisk gerbil has distinct features of a solitary species and its social structure is primarily based on aggressive interactions or mutual avoidance of conspecifics resulting in a dominance hierarchy among males and site-dependent dominance among females during the breeding season. By the end of the breeding season, males become less mobile and occupy nearly exclusive home ranges, consistent with solitary living. The main features of the spatial and social organization of this species, which distinguish it from other solitary rodents, are the higher mobility of males and the formation of temporary multimale–multifemale aggregations during the breeding season. Overall, the data presented expand our understanding of socioecology of gerbils.

The human specific bacterial pathogen Helicobacter pylori (H. pylori) is associated with severe gastric diseases, including gastric cancer. Recently, the increasing resistance makes the usage of antibiotics less effectively. Therefore, development of a new antimicrobial agent is required to control H. pylori infection. In the current study, the inhibitory effect of β-caryophyllene on H. pylori growth, as well as the antibacterial therapeutic effect, has been demonstrated. β-caryophyllene inhibited H. pylori growth via the downregulation of dnaE, dnaN, holB, and gyrA and also downregulated virulence factors such as CagA, VacA, and SecA proteins. β-caryophyllene inhibited expression of several T4SS components, so that CagA translocation into H. pylori-infected AGS gastric cancer cells was decreased by β-caryophyllene treatment. β-caryophyllene also inhibited VacA entry through the downregulation of T5aSS. After β-caryophyllene administration on Mongolian gerbils, the immunohistochemistry (IHC) and Hematoxylin&Eosin stains showed therapeutic effects in the treated groups. Hematological data, which was consistent with histological data, support the therapeutic effect of β-caryophyllene administration. Such a positive effect of β-caryophyllene on H. pylori infection potently substantiates the natural compound as being capable of being used as a new antimicrobial agent or functional health food to help patients who are suffering from gastroduodenal diseases due to H. pylori infection.