High levels of mitochondrial dynamics, autophagy, and apoptosis contribute to stable testicular status in hibernating Daurian ground squirrels.

Daurian ground squirrels (Spermophilus dauricus) experience various stress states during winter hibernation, but the impact on testicular function remains unclear. This study focused on the effects of changes in testicular autophagy, apoptosis, and mitochondrial homeostasis signaling pathways at various stages on the testes of Daurian ground squirrels. Results indicated that: (1) During winter hibernation, there was a significant increase in seminiferous tubule diameter and seminiferous epithelium thickness compared to summer. Spermatogonia number and testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels were higher during inter-bout arousal, suggesting that the testes remained stable during hibernation. (2) An increased number of mitochondria with intact morphology were observed during hibernation, indicating that mitochondrial homeostasis may contribute to testicular stability. (3) DNA fragmentation was evident in the testes during the hibernation and inter-bout arousal stages, with the highest level of caspase3 enzyme activity detected during inter-bout arousal, together with elevated levels of Bax/Bcl-2 and Lc3 II/Lc3 I, indicating an up-regulation of apoptosis and autophagy signaling pathways during hibernation. (4) The abundance of DRP1, MFF, OPA1, and MFN2 proteins was increased, suggesting an up-regulation of mitochondrial dynamics-related pathways. Overall, testicular autophagy, apoptosis, and mitochondrial homeostasis-related signaling pathways were notably active in the extreme winter environment. The well-maintained mitochondrial morphology may favor the production of reproductive hormones and support stable testicular morphology.

Bartonella, Blechomonas and Trypanosoma in fleas from the long-tailed ground squirrel (Spermophilus undulatus) in northwestern China.

Fleas are known to be vectors for a variety of pathogens in veterinary medicine. However, no information is available on the presence of Bartonella and Trypanosomatidae in fleas of the long-tailed ground squirrel (LTGR, Spermophilus undulatus). The present study shows detection of these pathogens in LTGR fleas. During 2022-2023, a total of 396 fleas were collected from 91 LTGRs in 4 alpine regions of Xinjiang Uygur Autonomous Region (northwestern China) and grouped into 54 flea pools. Flea species were identified according to morphological characteristics and molecular data. In addition, all flea samples were analyzed for Bartonella with amplification and sequencing of a 380-bp part of the gltA gene and Trypanosomatidae with targeting the 18S rRNA (850-bp) and gGAPDH (820-bp) genes. The flea species included Frontopsylla elatoides elatoides (203), Neopsylla mana (49), and Citellophilus tesquorum dzetysuensis (144). Of 54 flea pools, seven (12.96%) tested positive for Bartonella, and three (5.56%) were positive for Trypanosomatidae. Based on BLASTn and phylogenetic analyses, i) Bartonella washoensis in F. elatoides elatoides and C. tesquorum dzetysuensis, and Bartonella rochalimae in F. elatoides elatoides were identified. Interestingly, a new haplotype within the species Ba. washoensis was discovered in C. tesquorum dzetysuensis; and ii) Blechomonas luni was confirmed in C. tesquorum dzetysuensis and Trypanosoma otospermophili in F. elatoides elatoides. Two Bartonella species and two Trypanosomatidae members were discovered for the first time in fleas from LTGRs. This study broadens our understanding of the geographic distribution and potential vectors for Bartonella and Trypanosomatidae.

The phylogroups and antibiotic susceptibilities of Escherichia coli isolates from the feces of Anatolian Ground Squirrels (Spermophilus xanthoprymnus).

The current study was conducted to determine the phylogroups and antibiotic susceptibilities of Escherichia coli isolates recovered from fecal samples of Anatolian Ground Squirrels (Spermophilus xanthoprymnus) and to examine the relationship between them. Eighty-two E. coli isolates obtained from 150 fecal samples were investigated. The quadruplex polymerase chain reaction (PCR), phylogroup C-, and E-specific mPCR were subjected to phylogenetic typing of the isolates. The susceptibilities to fifteen antibiotics of the isolates were detected by the disk diffusion method. In the result of phylogenetic typing, phylogroup B2 was most predominant (58.6 %), followed by B1 (25.6 %), E (8.5 %), C (4.9 %), and D (2.4 %). The phylogroup A, F, and Escherichia clades were not detected. The antibiotic susceptibility test revealed that 59.8 % (49/82) and 19.5 % (16/82) of E. coli isolates were resistant to at least one antibiotic and multidrug-resistant (MDR), respectively. Twenty-six (31.7 %), 19 (23.2 %), 11 (13.4 %), and 10 (12.2 %) of the isolates were found to be resistant to gentamicin, tetracycline, amoxicillin-clavulanic acid, and cefoxitin. Of the 49 E. coli isolates that were found to be resistant to any antibiotic analyzed, 30, 13, 4, and 2 were located in phylogroup B2, B1, E, and D, respectively. MDR isolates were mostly located in both phylogroup B1 (31.3 %) and B2 (31.3 %). In conclusion, data from the current study suggest that the isolates may potentially have pathogenic properties, since the majority (69.5 %) of E. coli isolates from fecal samples of Spermophilus xanthoprymnus were located in the pathogenic phylogroup and resistance to various antibiotics was detected.

Intestinal parasites of the endangered European ground squirrel (Spermophilus citellus) populations in Slovakia.

The present pilot research was focused on the detection of intestinal parasites in the ground squirrel populations in various regions of Slovakia. Only a very little information is currently available on the parasitic species composition of the European ground squirrel in Slovakia and across Europe. In the Slovak Republic, there are 70 locations where the ground squirrel populations are present. A total of 600 faecal samples of the European ground squirrels, collected from 36 locations all over Slovakia, were examined by applying the coprological method. The presence of the protozoan coccidian parasite of the Eimeria genus was confirmed in all of the analysed locations. The presence of eggs of four helminths were confirmed: Capillaria spp. (66.6% of locations); the Trichostrongylidae family (42.8% of locations); Hymenolepis spp. (11.9% of locations); and Citellina spp. (7.14% of locations). Dead individuals that were found in the analysed localities were subjected to necropsy and the tissues scraped off their small intestines were stained in order to confirm the presence of parasites. The post-mortem examination of the intestines and the sedimentation of the intestinal contents in a saline solution did not result in the confirmation of the presence of the eggs, adults or the larval stages of parasites. Spermophilus citellus is one of the strictly protected animal species in Slovakia. In recent years, numerous projects aimed at supporting and protecting ground squirrels have been implemented. The present pilot study on intestinal parasites and the subsequent cooperation with environmental activists will contribute to the support and stabilisation of the presence of these animals in our country.

First complete mitochondrial genome of the Alashan ground squirrel (Spermophilus alashanicus) (Rodentia: Sciuridae) from Ningxia, China.

The Alashan ground squirrel (Spermophilus alashanicus) is primarily distributed in the regions of Inner Mongolia and Ningxia, China. In this study, we present the first complete mitochondrial genome of S. alashanicus. The genome spans 16,464 base pairs and comprises 13 protein-coding genes, 22 tRNA genes, two rRNA genes, and a single control region with a marked AT bias. The overall GC content is 35.4%. Phylogenetic analyses indicate that S. alashanicus clusters are closely associated with S. dauricus. This comprehensive characterization of the S. alashanicus mitochondrial genome serves as a foundational resource for future studies on mitochondrial evolution, species identification, population genomics, and phylogenetics.

Integrated metabolomics and proteomics analysis to understand muscle atrophy resistance in hibernating Spermophilus dauricus.

Hibernating Spermophilus dauricus experiences minor muscle atrophy, which is an attractive anti-disuse muscle atrophy model. Integrated metabolomics and proteomics analysis was performed on the hibernating S. dauricus during the pre-hibernation (PRE) stage, torpor (TOR) stage, interbout arousal (IBA) stage, and post-hibernation (POST) stage. Time course stage transition-based (TOR vs. PRE, IBA vs. TOR, POST vs. IBA) differential expression analysis was performed based on the R limma package. A total of 14 co-differential metabolites were detected. Among these, l-cystathionine, l-proline, ketoleucine, serine, and 1-Hydroxy-3,6,7-Trimethoxy-2, 8-Diprenylxanthone demonstrated the highest levels in the TOR stage; Beta-Nicotinamide adenine dinucleotide, Dihydrozeatin, Pannaric acid, and Propionylcarnitine demonstrated the highest levels in the IBA stage; Adrenosterone, PS (18:0/14,15-EpETE), S-Carboxymethylcysteine, TxB2, and 3-Phenoxybenzylalcohol demonstrated the highest levels in the POST stage. Kyoto Encyclopedia of Genes and Genomes pathways annotation analysis indicated that biosynthesis of amino acids, ATP-binding cassette transporters, and cysteine and methionine metabolism were co-differential metabolism pathways during the different stages of hibernation. The stage-specific metabolism processes and integrated enzyme-centered metabolism networks in the different stages were also deciphered. Overall, our findings suggest that (1) the periodic change of proline, ketoleucine, and serine contributes to the hindlimb lean tissue preservation; and (2) key metabolites related to the biosynthesis of amino acids, ATP-binding cassette transporters, and cysteine and methionine metabolism may be associated with muscle atrophy resistance. In conclusion, our co-differential metabolites, co-differential metabolism pathways, stage-specific metabolism pathways, and integrated enzyme-centered metabolism networks are informative for biologists to generate hypotheses for functional analyses to perturb disuse-induced muscle atrophy.

Surrounded by Kindred: Spermophilus major Hybridization with Other Spermophilus Species in Space and Time.

Among the numerous described cases of hybridization in mammals, the most intriguing are (a) cases of introgressive hybridization deeply affecting the evolutionary history of species, and (b) models involving not a pair of species but a multi-species complex. Therefore, the hybridization history of the russet ground squirrel Spermophilus major, whose range has repeatedly changed due to climatic fluctuations and now borders the ranges of four related species, is of great interest. The main aims of this study were to determine the direction and intensity of gene introgression, the spatial depth of the infiltration of extraneous genes into the S. major range, and to refine the hypothesis of the hybridogenic replacement of mitochondrial genomes in the studied group. Using phylogenetic analysis of the variability of mitochondrial (CR, cytb) and nuclear (SmcY, BGN, PRKCI, c-myc, i6p53) markers, we determined the contribution of neighboring species to the S. major genome. We showed that 36% of S. major individuals had extraneous alleles. All peripheral species that were in contact with S. major contributed towards its genetic variability. We also proposed a hypothesis for the sequence and localization of serial hybridization events. Our assessment of the S. major genome implications of introgression highlights the importance of implementing conservation measures to protect this species.

Infection by a previously uncharacterized Ehrlichia species in rodents from Inner Mongolia, Northern China.

Ehrlichia are intracellular bacteria of medical importance to both humans and domestic animals. They are mainly vectored by ticks and harbored by domestic and wild animals such as rodents. In this study, we investigated the prevalence and genetic diversity of Ehrlichia in rodents from Inner Mongolia Autonomous Region, Northern China. In 2021, a total of 359 rodents representing 10 species were captured in two locations of Inner Mongolia: Siziwang Banner and Ar Horqin Banner. Subsequently, an Ehrlichia was detected and characterized in three Spermophilus dauricus and one Meriones unguiculatus. Its rrs, gltA, and groEL sequences have the highest identities of 100%, 87.9%, and 99.7% to known Ehrlichia species, respectively, and they form distinct clades in the phylogenetic trees. Ehrlichia strains mostly related to this species have been detected in ticks from Russia, suggesting that it may be exposed to humans and animals through tick bites. The pathogenicity of this Ehrlichia should be further studied.

Transcriptomic and proteomic time-course analyses based on Metascape reveal mechanisms against muscle atrophy in hibernating Spermophilus dauricus.

Hibernating Spermophilus dauricus is resistant to muscle atrophy. Comprehensive transcriptome and proteome time-course analyses based on Metascape can further reveal the underlying processes (pre-hibernation stage, PRE; torpor stage, TOR; interbout arousal stage, IBA; and post-hibernation stage, POST). Transcriptome analysis showed that the cellular responses to growth factor stimulus and discrete oxygen levels continuously changed during hibernation. Proteomic analysis showed that neutrophil degranulation, sulfur compound metabolic process, and generation of precursor metabolites and energy continuously changed during hibernation. Molecular complex detection (MCODE) analysis in both transcriptome and proteome indicated that smooth muscle contraction was involved in the POST versus IBA stage, and peroxisome proliferator-activated receptor delta (Ppard), Myc proto-oncogene (Myc), Sp1 transcription factor (Sp1), and nuclear factor Kappa B subunit 1 (NFκB1) are the common TFs during the hibernation process. Integrated transcriptome and proteome analyses found 18 molecules in the TOR versus PRE stage, 1 molecule in the IBA versus TOR stage, and 16 molecules in the POST versus IBA stage. Among these molecules, carnitine palmitoyltransferase 1A (Cpt1a), SET and MYND domain containing 2 (Smyd2), four and a half LIM domains 1(Fhl1), reactive oxygen species modulator 1 (Romo1), and translocase of the inner mitochondrial membrane 50 (Timm50) were testified by Western blot. In conclusion, novel muscle atrophy resistance mechanisms can be deciphered by time-course transcriptome and proteome analyses based on Metascape.

Analysis of plague monitoring results in natural focus of Marmota sibirica plague in Hulunbuir Plateau from 2009 to 2020 / 中华地方病学杂志

Objective:To analyze the plague monitoring results of Marmota sibirica plague natural focus in Hulunbuir Plateau, and to study the characteristics of development and variation of the plague focus. Methods:From 2009 to 2020, monitoring was conducted in Manzhouli City, Prairie Chenbarhu Banner, Xin Barag Left Banner, and Xin Barag Right Banner from May to September each year. The one-day bow-clip method was used to investigate the density of the Spermophilus dauricus, and the 5-meter clamp method was used to investigate other small rodents. The classification and identification of ectoparasite fleas were done by using low power microscope. According to "Diagnostic Criteria for Plague" (WS 279-2008), the detectable materials of rats and fleas were tested, and Yersinia pestis was isolated and cultured. The serums of collected rats were detected by indirect hemagglutination test. Results:From 2009 to 2020, the average density of dauricus in Marmota sibirica plague natural focus of Hulunbuir Plateau was 0.45/hm 2, and the capture rate of other small rodents was 1.25% (787/63 091). A total of 9 species, 8 genera and 4 families of rodents were captured. The total flea infection rate of Spermophilus dauricus was 28.37% (1 945/6 856) and the fleas index was 1.04. A total of 3 species, 3 genera and 2 families of fleas were collected. A total of 6 674 Spermophilus dauricus were dissected and 6 787 fleas were cultured in 2 537 groups. The Yersinia pestis test was negative. A total of 6 795 serum samples from Spermophilus dauricus were detected, of which 11 were positive with a positive detection rate of 0.16%. The highest titer of positive serum was 1∶1 280. Indirect hemagglutination test positive materials were found for 5 consecutive years from 2010 to 2014; the positive serums were found in Manzhouli City and Xin Barag Right Banner. Conclusions:The Yersinia pestis antibady positive serum of Spermophilus dauricus has been detected in Marmota sibirica plague focus of Hulunbuir Plateau for many years, which is worthy of high vigilance. In the future, continuous surveillance should be carried out, bacterial detection should be strengthened, possible plague outbreaks should be detected in time, and various plague prevention and control should be done well.

Erythrocytes of Little Ground Squirrels Undergo Reversible Oxidative Stress During Arousal From Hibernation.

The hibernation of small mammals is characterized by long torpor bouts alternating with short periods of arousal. During arousal, due to a significant increase in oxygen consumption, tissue perfusion, and the launch of thermogenesis in cells, a large amount of reactive oxygen species (ROS) and nitrogen (RNS) can be formed, which can trigger oxidative stress in cells. To estimate this possibility, we studied the intensity of free-radical processes in the red blood cells (RBCs) of little ground squirrels (LGS; Spermophilus pygmaeus) in the dynamics of arousal from hibernation. We found that in the torpid state, the degree of generation of ROS and RNS (8.3%, p>0.09; 20.7%, p<0.001, respectively), the degree of oxidative modification of membrane lipids and RBC proteins is at a low level (47%, p<0.001; 82.7%, p<0.001, respectively) compared to the summer control. At the same time, the activity of superoxide dismutase (SOD) and catalase (CAT) in RBC is significantly reduced (32.8%, p<0.001; 22.2%, p<0.001, respectively), but not the level of glutathione (GSH). In the torpid state, SOD is activated by exogenous GSH in concentration-dependent manner, which indicates reversible enzyme inhibition. During the arousal of ground squirrels, when the body temperature reaches 25°C, RBCs are exposed oxidative stress. This is confirmed by the maximum increase in the level of uric acid (25.4%, p<0.001) in plasma, a marker of oxidative modification of lipids [thiobarbituric acid reactive substances (TBARS); 82%, p < 0.001] and proteins (carbonyl groups; 499%, p < 0.001) in RBC membranes, as well as the decrease in the level of GSH (19.7%, p < 0.001) in erythrocytes relative to the torpid state and activity of SOD and CAT in erythrocytes to values at the Tb 20°C. After full recovery of body temperature, the level of GSH increases, the ratio of SOD/CAT is restored, which significantly reduces the degree of oxidative damage of lipids and proteins of RBC membranes. Thus, the oxidative stress detected at Tb 25°C was transient and physiologically regulated.

Individual-based acoustic variation of the alarm calls in the long-tailed ground squirrel.

Based on their phylogenetic position, Nearctic ground squirrels are closest relatives to the long-tailed ground squirrel Urocitellus undulates even though it has Palaearctic distribution. We aimed to investigate the variability of alarm calls of the long-tailed ground squirrel to test the individual variation in alarm calls. This species is known to produce two types of alarm calls: whistle alarms and wideband calls. Although ground squirrels are a model group for the study of vocal individuality, this phenomenon has not yet been studied in a species producing two such completely different types of alarms. Most of ground squirrel species produce either whistle or wideband alarms and this species represents a unique model for testing the degree of individual variability depending on completely different acoustic structures. We analysed 269 whistle alarms produced by 13 individuals and 591 wideband alarms from 25 individuals at the western part of Lake Baikal. A discriminant function analysis (DFA) assigned 93.5% (88.9%, cross-validated result) of whistle alarms to the correct individual and 91.4% (84%) of wideband alarms. This is the first evidence of individual variation in wideband alarms compared with whistle alarms and occurrence of vocal individuality in two warning signals of a completely different acoustic structure produced by a ground squirrel.

Cold exposure increased hypothalamic orexigenic neuropeptides but not food intake in fattening Daurian ground squirrels.

Energy balance and thermoregulation in many fat-storing seasonal hibernators show a circannual rhythm. To understand the physiological mechanisms of the seasonal pre-hibernation fattening related to the regulation of energy expenditure and thermogenesis, we cold-exposed fattening Daurian ground squirrels (Spermophilus dauricus) in late summer for 3 weeks. We predicted that cold-exposed squirrels would increase food intake rather than express torpor to accommodate both fattening and thermoregulatory fuel allocation. Food intake and body mass were quantified. After 3 weeks, body compositions, serum leptin concentration, expression of hypothalamic neuropeptides related to regulation of energy balance and uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) were measured. There was no change in body mass after 3-weeks of cold exposure. Hypothalamic orexigenic neuropeptides and UCP1 levels in BAT were up-regulated after cold exposure. Food intake, serum leptin concentration and the expression of leptin signal suppressors, suppressor of cytokine signaling 3 and protein tyrosine phosphatase 1B, in hypothalamus showed no differences compared with controls. The core body temperature was unaffected by cold exposure. Our data suggest that cold exposure affected fattening mainly because of the increased heat loss, whereas energy balance and thermoregulation are under control of a strong circannual rhythm in the Daurian ground squirrels.

Geographic variability in the alarm calls of the European ground squirrel.

Geographic variability in vocalizations has been documented in many mammalian species. We examined to what extent it applies to the alarm calls of the European ground squirrel Spermophilus citellus. We recorded the calls of 82 adult individuals from 5 natural colonies in the Czech Republic and 24 adult individuals from an artificial seminatural colony located in a Czech zoo. The founders of this colony originated from 4 different natural colonies in the Czech Republic. Our results showed that there are hardly any differences in the acoustic structure of the alarm calls between male and female European ground squirrels. Discriminant function analysis showed the highest degree of discriminability for the most isolated sites (54-74% of individuals classified correctly), whereas the lowest degree of discriminability was found for 2 interconnected colonies (38-40% individuals classified correctly). Individuals from the artificial seminatural colony were often classified correctly to this colony (58% classified correctly); however, the precision of the classification was comparatively relatively low, that is, many individuals from other colonies were incorrectly classified into this seminatural colony. This likely corresponds to the different origins of its founders. These findings indicate that there is a rather substantial geographic variability in the alarm calls of the European ground squirrel, and our study highlights its possible impact on conservation measures such as establishing artificial colonies or reintroductions.

Expression patterns of natriuretic peptides in pre-hibernating and hibernating Anatolian ground squirrel (Spermophilus xanthoprymnus) kidney.

Hibernation is characterized by marked suppression of renal function. Natriuretic peptides (NPs) are involved in the regulation of renal function. However, the role of NPs in the renal function during hibernation remains unclear. We aimed to investigate the distribution patterns of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) in Anatolian ground squirrel (Spermophilus xanthoprymnus) kidneys during pre-hibernation and hibernation periods. Cortical proximal tubules showed weak ANP immunoreactivity, with moderate staining on the brush border during the pre-hibernation period. In the hibernation period, moderate ANP immunoreactivity was seen in cortical proximal tubules, with very weak reaction in hibernating cortical distal tubules, medullary proximal and collecting tubules. Cortical proximal and distal tubules of both periods had strong and weak BNP immunoreactivity, respectively. Medullary proximal, distal and Henle's loop segments showed very weak BNP immunoreactivity during pre-hibernation. Medullary distal, proximal and collecting tubules and Henle's loop segments had moderate staining during hibernation. In both periods, cortical proximal tubules displayed strong immunoreactivity to CNP. Distal tubules had moderate CNP staining during pre-hibernation, albeit weak staining during hibernation. Medullary proximal tubules exhibited moderate to strong immunoreactivity during pre-hibernation. Medullary distal and proximal tubules had weak and moderate CNP staining, respectively, during pre-hibernation. In both periods, Henle's loop segments displayed moderate CNP immunoreactivity. Glomeruli had similar weak ANP, BNP and CNP staining in both periods. These results suggest that heterothermic conditions differently affected the expression of NPs in the squirrel kidney. This different expression of NPs may contribute to the renal adaptation during hibernation.

The role of ant nests in European ground squirrel's (Spermophilus citellus) post-reintroduction adaptation in two Bulgarian mountains.

The European ground squirrel (Spermophilus citellus) is a vulnerable species, whose populations are declining throughout its entire range in Central and South-Eastern Europe. To a great extent, its conservation depends on habitat restoration, maintenance and protection. In order to improve the conservation status of the species, reintroductions are increasingly applied. Therefore, researchers focus their attention on factors that facilitate these activities and contribute to their success. In addition to the well-known factors like grass height and exposition, others, related to the underground characteristics, are more difficult to evaluate. The presence of other digging species could help this evaluation. Here, we present two reintroduced ground squirrel colonies, where the vast majority of the burrows are located in the base of anthills, mainly of yellow meadow ant (Lasius flavus). This interspecies relationship offers numerous advantages for the ground squirrel and is mostly neutral for the ants. The benefits for the ground squirrel, including reduced energy demand for digging, as well as additional surveillance and hiding places available, could greatly enhance the post-reintroduction adaptation process.

Expression patterns of natriuretic peptides in pre-hibernating and hibernating anatolian ground squirrel (Spermophilus xanthoprymnus) lung.

Anatolian ground squirrel (Spermophilus xanthoprymnus) is a true hibernator. This animal transiently reduces pulmonary function during hibernation. Continuance of pulmonary function is very important to survive ground squirrels during the hibernation. Natriuretic peptides may be key players in the modulation of pulmonary hemostasis. However, NPs' role in pulmonary function during hibernation remains unclear. We aimed to investigate the localization and distribution of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) in squirrel lungs during pre-hibernation and hibernation periods using immunohistochemistry. Our immunohistochemical data indicate that ANP, BNP, and CNP were produced by the mucosal epithelium of terminal and respiratory bronchioles, smooth muscle cells in the lamina propria of terminal bronchioles and vascular smooth muscle cells, alveolar type II cells, and macrophages. ANP immunoreactivity was weaker than BNP and CNP immunoreactivities in these cells. The results also demonstrate that the number of ANP, BNP and CNP positive alveolar type II cells tended to increase, although statistically non-significant, during the hibernation period, but the expression of NPs in other pulmonary cells is unaffected by hibernation. This study firstly investigates ANP, BNP and CNP distribution in the Anatolian ground squirrel lung. However, further studies are required to dissect their functional roles during the hibernation.

Rickettsia raoultii and Rickettsia sibirica in ticks from the long-tailed ground squirrel near the China-Kazakhstan border.

Spotted fever group (SFG) rickettsiae cause infection in humans, domestic animals and wildlife. To date, no rickettsial agents have been reported in hard ticks from the long-tailed ground squirrel (Spermophilus undulatus). A total of 50 adult ticks and 48 nymphs were collected from S. undulatus in the border region of northwestern China. Tick species (identified according to morphological and molecular characteristics) included Dermacentor nuttalli, Dermacentor silvarum and Ixodes kaiseri. Based on the cytochrome c oxidase subunit I (COI) haplotype analysis, I. kaiseri from S. undulatus belongs to an ancestral. In addition, all tick samples were analyzed for the presence of rickettsiae by PCR amplification and sequencing of six genetic markers. Rickettsia raoultii and Rickettsia sibirica subsp. sibirica were shown to occur in adults and nymphs of D. nuttalli and D. silvarum. Rickettsia sibirica subsp. sibirica was also detected in an I. kaiseri adult. Dermacentor silvarum and I. kaiseri were found for the first time on S. undulatus. Rickettsia raoultii and R. sibirica subsp. sibirica were detected in two Dermacentor and one Ixodes species, respectively, suggesting that these rickettsiae circulate in the region of the China-Kazakhstan border by hard ticks infesting S. undulatus.

Localization profiles of natriuretic peptides in hearts of pre-hibernating and hibernating Anatolian ground squirrels (Spermophilus xanthoprymnus).

The Anatolian ground squirrel (Spermophilus xanthoprymnus) is a typical example of true mammalian hibernators. In order to adapt to extreme external and internal environments during hibernation, they lower their body temperatures, heart rates and oxygen consumption; however, pathological events such as ischemia and ventricular fibrillation do not occur in their cardiovascular systems. During the hibernation, maintenance of cardiac function is very important for survival of ground squirrels. Natriuretic peptides (NPs) are key factors in the regulation of cardiovascular hemostasis. Since NPs' role on the protection of heart during hibernation are less clear, the aim of this study was to investigate dynamic changes in NPs content in the cardiac chambers and to reveal the possible role of NPs on establishing cardiac function in ground squirrel during hibernation using immunohistochemistry. The immunohistochemical results indicate that cardiac NP expressions in atrial and ventricular cardiomyocytes were different from each other and were sex-independent. ANP and BNP were expressed in a chamber-dependent manner in female and male squirrel hearts. Furthermore, cardiac NPs expression levels in hibernation period were lower than those at the pre-hibernation period. During prehibernation period, ANP, BNP and CNP were expressed in the white and beige adipocytes of epicardial adipose tissue (EAT); while during hibernation period, the brown adipocytes of EAT were positive for BNP and CNP. These data suggest that the hibernation-dependent reduction in levels of NPs, particularly ANP, in cardiac chambers and EAT may be associated with low heart rate and oxygen consumption during hibernation. However, further studies are needed to better delineate the roles of NPs during the hibernation.

Relationship between environmental factors and the spatial distribution of Spermophilus dauricus during 2000-2015 in China.

The Spermophilus dauricus is a rodent species that feeds on the tender parts of plants and seeds. It is also a natural carrier of the hepatitis B virus and the main host of the plague bacillus Yersinia pestis threatening human health and the cultivated ecosystems. Based on ecological niche modeling (ENM) for the MaxEnt model and ArcGIS for the Spatial Analyst model, we quantified the potential risk zone and spatial pattern of the S. dauricus outbreak during 2000-2015. We analyze the temporal and spatial variation for different levels of risk zones. The results showed that the S. dauricus was primarily distributed in the North China with arid and semi-arid regions. The suitable habitat of S. dauricus includes an annual precipitation of 250-700 mm year-1, a temperature of - 3 to 14 °C, the normalized differential vegetation index (NDVI) of 0.05-0.65, and an elevation of < 3800 m. Although the NDVI and precipitation were significantly increasing, the potential risk zone did not expand. But, this result can not mean the S. dauricus outbreak had been controlled, and the substantial additional efforts in the form of observational and/or experimental investigations are needed to explore the relationships between environmental factors and the habitat of the S. dauricus, ideally by including the influences from land cover, vegetation characteristics, and artificial disturbances.