Search

Antibiotic resistance genes (ARGs) carried by gut pathogens may pose a threat to the host and ecological environment. However, few studies focus on the effects of cold stress on intestinal bacteria and ARGs in plateau animals. Here, we used 16S rRNA gene sequencing and gene chip technique to explore the difference of gut microbes and ARGs in plateau pika under 4 °C and 25 °C. The results showed that tetracycline and aminoglycoside resistance genes were the dominant ARGs in pika intestine. Seven kinds of high-risk ARGs (aadA-01, aadA-02, ermB, floR, mphA-01, mphA-02, tetM-02) existed in pika's intestine, and cold had no significant effect on the composition and structure of pika's intestinal ARGs. The dominant phyla in pika intestine were Bacteroidetes and Firmicutes. Cold influenced 0.47 % of pika intestinal bacteria in OTU level, while most other bacteria had no significant change. The diversity and community assembly of intestinal bacteria in pika remained relatively stable under cold conditions, while low temperature decreased gut microbial network complexity. In addition, low temperature led to the enrichment of glycine biosynthesis and metabolism-related pathways. Moreover, the correlation analysis showed that eight opportunistic pathogens (such as Clostridium , Staphylococcus , Streptococcus , etc.) detected in pika intestine might be potential hosts of ARGs. [Display omitted] • Tetracycline and aminoglycoside resistance genes were the dominant ARGs in pika intestine. • Seven kinds of high-risk ARGs were located in pika intestine and cold stress had no significant effect on them. • Cold stress had no significant effect on the intestinal bacterial structure and assembly process of pika. • Staphylococcus was the potential host of high-risk ARGs mphA-01 in pika gut. [ABSTRACT FROM AUTHOR]

Abstract During evolution, animals optimize their reproductive strategies to increase offspring survival. Seasonal breeders reproduce only during certain times of the year. In mammals, reproduction is tightly controlled by hypothalamus-pituitary-gonad axis. Although pathways regulating gametogenesis in non-seasonal model species have been well established, molecular insights into seasonal reproduction are severely limited. Using the Plateau pika (Ochotona curzoniae), a small rodent animal species native to the Qinghai-Tibetan plateau, as a model, here we report that seasonal spermatogenesis is governed at the level of spermatogonial differentiation. In testis of the reproductively dormant animals, undifferentiated spermatogonia failed to differentiate and accumulated in the seminiferous tubules. RNA-seq analyses of the active and dormant testes revealed that genes modulating retinoic acid biogenesis and steriodogenesis were differentially regulated. A single injection of all-trans retinoic acid (ATRA) reinitiated spermatogenesis and inhibition the function of RA-degrading enzyme CYP26B1 for 10 days induced spermatogonial differentiation. Strikingly, testosterone injection reinitiated spermatogenesis in short day adapted animals. Testosterone provides a permissive environment of RA biogenesis and actions in testis, therefore, indirectly controls spermatogonial differentiation. Collectively, these findings provide a key mechanistic insight regarding the molecular regulation of seasonal reproduction in mammals. Graphical abstract Image 1 Highlights • Seasonal spermatogenesis is governed at the phase of sprematogonial differentiation in the Plateau Pika. • Genes modulating retinoic acid biogenesis were differentially regulated in the reproductively dormant testis. • A single injection of all-trans retinoic acid induced spermatogonial differentiation and resumption of spermatogenesis. • Testosterone is the master regulator of seasonal spermatogenesis by regulating retinoic acid biogenesis. [ABSTRACT FROM AUTHOR]

Echinococcus multilocularis (Em), a parasitic tapeworm, is responsible for a significant burden of human disease across continental Asia. Here, we use a time-series of MODIS 16-day 250 m Enhanced Vegetation Index (EVI) satellite data to quantify the seasonal vegetation dynamics across a study area in Serxu County, Sichuan Province, China, in relation to the presence of the Em intermediate host Ochotona curzoniae (plateau pika) and Ochotona cansus (Gansu pika) (here merged to Ochotona spp.). A series of derived phenological metrics are analysed using the random forests statistical method to determine the relative importance of seasonal vegetation characteristics. Results indicate negative relationships between Ochotona spp. presence and EVI showing a preference for low-biomass habitats. However, EVI values during green-up and senescence periods are also shown to be important, potentially resulting from improved detectability of low-biomass grassland habitats at these times. Improved detection of Ochotona spp. preferred habitats via time-series EVI imagery offers better understanding of the distributions of this Em host, and the potential for monitoring the changes in Ochotona spp. optimal habitat distributions resulting from landscape change. This could aid the identification of villages at increased risk of infection, enabling preventive strategies to be adopted. [ABSTRACT FROM AUTHOR]

The plateau pika (Ochotona curzoniae) is native to the Qinghai-Tibet Plateau. In this study, the gene that encodes a heme-binding protein in the pulmonary surfactant (PS) of the pika is identified. The protein is a homotetrameric hemoglobin (δ 4) encoded by HBD (δ). HBD is expressed in alveolar epithelial type II (ATII) and type I (ATI) cells, upregulated by hypoxia. δ 4 is secreted into alveolar cavities through osmiophilic multilamellar bodies. HBD expression is downregulated by RNAi, which significantly increases hypoxia-inducible factor 1α expression in lung tissue and red blood cells and hemoglobin and blood lactate concentrations but significantly decreases arterial partial pressure of oxygen (PaO 2). Our results indicate that plateau pikas physiologically show hypoxemia when HBD expression is downregulated. Therefore, specific HBD expression in the lungs helps plateau pikas to obtain oxygen under hypoxia by maintaining higher PaO 2. These findings provide insights into the adaptive mechanisms of plateau pikas to withstand high-altitude environments. [Display omitted] • HBD (δ) is expressed specifically in lungs of the plateau pika • HBD is expressed not only in ATII but also in ATI cells • δ 4 encoded by HBD gene is secreted into alveolar cavities through LBs • δ 4 maintains higher PaO 2 and helps plateau pikas to adapt to hypoxic environments An et al. demonstrate that the HBD (δ) gene of the β-globin gene cluster is expressed specifically in the lungs of the plateau pika in the form of δ 4. The δ 4 is secreted into alveolar cavities, maintains higher arterial oxygen partial pressure, and helps plateau pikas to adapt to hypoxic environments. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the different ventilatory strategies that help in coping with hypoxic–hypercapnia environment among two species: use acclimated rats and plateau pikas ( Ochotona curzoniae ) that live in Tibetan plateaus, and have been well adjusted to high altitude. Arterial blood samples taken at 4100 m of elevation in acclimatized rats and adapted pikas revealed inter-species differences with lower hemoglobin and hematocrit and higher blood pH in pikas. A linear and significant increase in minute ventilation was observed in pikas, which help them to cope with hypoxic–hypercapnia. Pikas also displayed a high inspiratory drive and an invariant respiratory timing regardless of the conditions. Biochemical analysis revealed that N-methyl- D -aspartate receptor (NMDA) receptor gene and nNOS gene are highly conserved between rats and pikas, however pikas have higher expression of NMDA receptors and nNOS compared to rats at the brainstem level. Taken together, these results suggest that pikas have developed a specific ventilatory pattern supported by a modification of the NMDA/NO ventilatory central pathways to survive in extreme conditions imposed on the Tibetan plateaus. These physiological adaptive strategies help in maintaining a better blood oxygenation despite high CO 2 concentration in burrows at high altitude. [ABSTRACT FROM AUTHOR]

Abstract: The plateau pika (Ochotona curzoniae) inhabits the Qinghai/Tibetan Plateau of China. Its role on the grassland ecosystem is not quite understood. Some researchers regard it as a keystone species while others treat it as a pest. At least, the overabundance of plateau pika population accelerates degrading of alpine meadows mainly through their burrowing activity. Therefore, it is necessary to manage pika population. The commonly employed management strategies are lethal control, contraceptive control, and vegetation restoration. To study the control effect, we develop a cellular automata model. In the simulation, we consider three time manners (single control, impulsive control at fixed times and state-dependent impulsive control) and two space manners (uniform control and mosaic control). Not surprisingly, a better control effect can be achieved with a larger killing rate in lethal control, or a larger contraception rate, or a larger degree in grassland restoration. On the other hand, uniform control has distinctly better results than mosaic control. Hence, in practice, uniform control is strongly recommended. With uniform control, some results are summarized as follows. In both lethal control and contraceptive control, the best strategy is to apply state-dependent impulsive control; if control is implemented in the non-growing season then the implementation time makes no difference. However, if control is implemented in the breeding season of pika, in lethal control, the later it is implemented the better is the control effect; while in contraceptive control, the earlier it is implemented the better is the control effect. Compared with lethal control, non-disseminating contraceptive control has a better control result if only one control is implemented; but if controls are implemented too often then lethal control has a better control effect. [Copyright &y& Elsevier]

Abstract: Small mammals, such as European rabbits (Oryctolagus cuniculus), plateau pikas (Ochotona curzoniae) and prairie dogs (Cynomys spp.), traditionally have been perceived as pests and targeted for control within their native ranges, where they perform essential ecosystem roles and are considered keystone species. These species can reach high densities, and have been subjected to eradication campaigns because of their putative negative impact on natural habitats and agriculture and their competition with livestock for forage. Eradication programmes have been a main factor causing sharp declines of these species in their natural ranges. Paradoxically, they are keystone species where they are abundant enough to be perceived as pests. The term “pest” is usually a social perception that is rarely supported by scientific data, whereas there is considerable scientific evidence of the key ecological roles played by these species. We call for the conservation of these species and present a conceptual model regarding the management of their populations. Where they occur at high numbers, and hence their effects on biodiversity are still of crucial importance, the persecution of these species should be avoided and their natural habitats preserved. In areas with high conservation value, but where these species occur at low densities, management efforts should aim to increase their density. In areas of high commercial value, managers ideally should consider changing prioritization of the area to high conservation value by purchasing the land or obtaining conservation easements. In situations with high commercial value and demonstrable low conservation concern, small mammals could be reduced humanely. [Copyright &y& Elsevier]

Abstract: Pikas originated in Asia and are small lagomorphs native to cold climates. The plateau pika, Ochotona curzoniae is a keystone species on the Qinghai–Tibet Plateau and an ideal animal model for hypoxic adaptation studies. Altered mitochondrial function, especially cytochrome c oxidase activity, is an important factor in modulation of energy generation and expenditure during cold and hypoxia adaptation. In this study, we determined the complete nucleotide sequence of the O. curzoniae mitochondrial genome. The plateau pika mitochondrial DNA is 17,131bp long and encodes the complete set of 37 proteins typical for vertebrates. Phylogenetic analysis based on concatenated heavy-strand encoded protein-coding genes revealed that pikas are closer to rabbit and hare than to rat. This suggests that rabbit or hare would be a good control animal for pikas in cold and hypoxia adaptation studies. Fifteen novel mitochondrial DNA-encoded amino acid changes were identified in the pikas, including three in the subunits of cytochrome c oxidase. These amino acid substitutions potentially function in modulation of mitochondrial complexes and electron transport efficiency during cold and hypoxia adaptation. [Copyright &y& Elsevier]

Abstract: The high-altitude rangelands of the Trans-Himalaya represent a grazing ecosystem which has supported an indigenous pastoral community for millennia alongside a diverse assemblage of wild herbivores including burrowing mammals (pikas and voles). Pastoralists consider the small mammals to cause rangeland degradation and as competitors for their livestock, and actively eradicate them at many places. We present data on the ways in which small herbivores like pikas and voles mediate plant community dynamics. Vegetation cover and plant species richness were compared on and off both active and abandoned small mammal colonies. Plant species richness was higher inside colonies (about 4–5 species/plot) than outside (about 3 species/plot) whereas vegetation cover was only marginally lower (52% compared to 60%). Soil disturbance due to small mammals is seen to be associated with higher plant diversity without causing dramatic decline in overall vegetation cover. Such disturbance-mediated dynamics and vegetation mosaics produce a rich array of testable hypotheses that can highlight how small mammals influence assembly processes, succession, and dominance hierarchies in plant communities in this arid ecosystem. So, eradicating small mammals may lead to declining levels of diversity in this ecosystem, and compromise ecosystem-functioning. Changes in traditional pastoral practices and overstocking are more likely to be responsible for degradation. We emphasize that eradicating small mammals can lead to loss of diversity in this ecosystem and it is not a solution for the degradation problems. [Copyright &y& Elsevier]