Genomic Consequences of and Demographic Response to Pervasive Hybridization Over Time in Climate-Sensitive Pikas.

Rare and geographically restricted species may be vulnerable to genetic effects from inbreeding depression in small populations or from genetic swamping through hybridization with common species, but a third possibility is that selective gene flow can restore fitness (genetic rescue). Climate-sensitive pikas (Ochotona spp.) of the Qinghai-Tibetan Plateau (QHTP) and its vicinity have been reduced to residual populations through the movement of climatic zones during the Pleistocene and recent anthropogenic disturbance, whereas the plateau pika (O. curzoniae) remains common. Population-level whole-genome sequencing (n = 142) of six closely related species in the subgenus Ochotona revealed several phases of ancient introgression, lineage replacement, and bidirectional introgression. The strength of gene flow was the greatest from the dominant O. curzoniae to ecologically distinct species in areas peripheral to the QHTP. Genetic analyses were consistent with environmental reconstructions of past population movements. Recurrent periods of introgression throughout the Pleistocene revealed an increase in genetic variation at first but subsequent loss of genetic variation in later phases. Enhanced dispersion of introgressed genomic regions apparently contributed to demographic recovery in three peripheral species that underwent range shifts following climate oscillations on the QHTP, although it failed to drive recovery of northeastern O. dauurica and geographically isolated O. sikimaria. Our findings highlight differences in timescale and environmental background to determine the consequence of hybridization and the unique role of the QHTP in conserving key evolutionary processes of sky island species.

Phylogenomics of American pika (Ochotona princeps) lineage diversification.

Quaternary climate oscillations have profoundly influenced current species distributions. For many montane species, these fluctuations were a prominent driver in species range shifts, often resulting in intraspecific diversification, as has been the case for American pikas (Ochotona princeps). Range shifts and population declines in this thermally-sensitive lagomorph have been linked to historical and contemporary environmental changes across its western North American range, with previous research reconstructing five mitochondrial DNA lineages. Here, we paired genome-wide data (25,244 SNPs) with range-wide sampling to re-examine the number and distribution of intra-specific lineages, and investigate patterns of within- and among-lineage divergence and diversity. Our results provide genomic evidence of O. princeps monophyly, reconstructing six distinct lineages that underwent multiple rounds of divergence (0.809-2.81 mya), including a new Central Rocky Mountain lineage. We further found evidence for population differentiation across multiple spatial scales, and reconstructed levels of standing variation comparable to those found in other small mammals. Overall, our findings demonstrate the influence of past glacial cycles on O. princeps lineage diversification, suggest that current subspecific taxonomy may need to be revisited, and provide an important framework for investigations of American pika adaptive potential in the face of anthropogenic climate change.

Adlercreutzia wanghongyangiae sp. nov., and Adlercreutzia shanghongiae sp. nov., two new members of the genus Adlercreutzia isolated from plateau pika (Ochotona curzoniae).

Four anaerobic, Gram-stain-positive, non-motile, non-sporulating rod-shaped bacterial strains (R7T, R21, R22 and R25T) were isolated from the intestinal contents of plateau pika (Ochotona curzoniae) collected from the Qinghai-Tibet Plateau, PR China. The four isolates grew at between 25 and 42 °C (optimally at 35-37 °C), and with 0.3-3.3% NaCl (w/v) [optimum, 1.3% (w/v)]. Adding l-arginine to the medium could promote their growth. Strains R7T and R21 were most closely related to Adlercreutzia caecimuris B7T (97.48% 16S rRNA gene sequence similarity). Strains R25T and R22 were most closely related to Adlercreutzia equolifaciens DSM 19450T (98.25% 16S rRNA gene sequence similarity). The genome sequences of R7T and R25T were 2.89 and 2.90 Mb in size with 63.6 and 62.8 mol% DNA G+C contents, respectively. Phylogenetic analysis based on 16S rRNA gene sequences and core genes revealed that R7T and R21 were most closely related to A. caecimuris B7T and Adlercreutzia mucosicola DSM 19490T, whereas R25T and R22 were most closely related to A. equolifaciens DSM 19450T and Adlercreutzia rubneri ResAG-91T. R7T, R25T and the closely related species had average nucleotide identity (ANI) values of 81.9-83.2% as well as digital DNA-DNA hybridisation (dDDH) values between 27.3 and 27.9%, which clearly indicated that they represent two novel species within the genus Adlercreutzia. For R7T and R25T, meso-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan, and the whole cell sugars included galactose, glucose and ribose. On the basis of these results, we propose that strains R7T and R25T represent two novel species of the genus Adlercreutzia, namely Adlercreutzia wanghongyangiae sp. nov. and Adlercreutzia shanghongiae sp. nov., respectively. The type strains are R7T (=GDMCC 1.4459T=KCTC 25860T) and R25T (=GDMCC 1.4458T=KCTC 25861T).

Ecologically informed priors improve Bayesian model estimates of species richness and occupancy for undetected species.

Detection error can bias observations of ecological processes, especially when some species are never detected during sampling. In many communities, the probable identity of these missing species is known from previous research and natural history collections, but this information is rarely incorporated into subsequent models. Here, I present prior aggregation as a method for including information from external sources in Bayesian hierarchical detection models. Prior aggregation combines information from multiple prior distributions, in this case, an ecologically informative, species-level prior, and an uninformative community-level prior. This approach incorporates external information into the model without sacrificing the advantages of modeling species in the context of the community. Using simulated data supplied to a multispecies occupancy model, I demonstrated that prior aggregation improves estimates of (1) metacommunity richness and (2) environmental covariates were associated with species-specific occupancy probabilities. When applied to a dataset of small mammals in Vermont, prior aggregation allowed the model to estimate occupancy correlates of the Eastern cottontail Sylvilagus floridanus, a species observed at several sites in the region but never captured. Prior aggregation can be used to improve the analysis of several important metrics in population and community ecology, including abundance, survivorship, and diversity.

Typing of Leishmania isolates from vectors and leporids of the Madrid (Spain) outbreak.

In 2009, a large outbreak of leishmaniasis, associated with environmental changes, was declared near Madrid (Spain), in which Phlebotomus perniciosus was the vector, whereas the main reservoirs were hares and rabbits. Analysis of isolates from humans, vectors and leporids from the focus identified the Leishmania infantum ITS-Lombardi genotype. However, multilocus enzyme electrophoresis (MLEE), the reference technique for Leishmania typing, and sequencing of the hsp70 gene, a commonly used marker, were not performed. In the present study, 19 isolates from P. perniciosus (n = 11), hares (n = 5) and rabbits (n = 3) from the outbreak area, all characterized as ITS-Lombardi in previous studies, were analysed by MLEE and hsp70 sequencing. The hsp70 results confirmed that all the analysed strains are L. infantum. However, by MLEE, 4 different zymodemes of L. infantum were identified based on variable mobilities of the NP1 enzyme: MON-34 (NP1100, n = 11), MON-80 (NP1130, n = 6), MON-24 (NP1140, n = 1) and MON-331 (NP1150, n = 1). The relative frequency of these zymodemes does not correspond to their usual occurrence in Spain. Moreover, MON-34 and MON-80 were found in P. perniciosus, hares and rabbits for the first time. These findings continue to provide insights into the outbreak and call for further studies with a higher number of strains.

Pharmacokinetic/pharmacodynamic evaluation of gamithromycin against rabbit pasteurellosis.

BACKGROUND: Gamithromycin is an effective therapy for bovine and swine respiratory diseases but not utilized for rabbits. Given its potent activity against respiratory pathogens, we sought to determine the pharmacokinetic profiles, antimicrobial activity and target pharmacokinetic/pharmacodynamic (PK/PD) exposures associated with therapeutic effect of gamithromycin against Pasteurella multocida in rabbits. RESULTS: Gamithromycin showed favorable PK properties in rabbits, including high subcutaneous bioavailability (86.7 ± 10.7%) and low plasma protein binding (18.5-31.9%). PK analysis identified a mean plasma peak concentration (Cmax) of 1.64 ± 0.86 mg/L and terminal half-life (T1/2) of 31.5 ± 5.74 h after subcutaneous injection. For P. multocida, short post-antibiotic effects (PAE) (1.1-5.3 h) and post-antibiotic sub-inhibitory concentration effects (PA-SME) (6.6-9.1 h) were observed after exposure to gamithromycin at 1 to 4× minimal inhibitory concentration (MIC). Gamithromycin demonstrated concentration-dependent bactericidal activity and the PK/PD index area under the concentration-time curve over 24 h (AUC24h)/MIC correlated well with efficacy (R2 > 0.99). The plasma AUC24h/MIC ratios of gamithromycin associated with the bacteriostatic, bactericidal and bacterial eradication against P. multocida were 15.4, 24.9 and 27.8 h in rabbits, respectively. CONCLUSIONS: Subcutaneous administration of 6 mg/kg gamithromycin reached therapeutic concentrations in rabbit plasma against P. multocida. The PK/PD ratios determined herein in combination with ex vivo activity and favorable rabbit PK indicate that gamithromycin may be used for the treatment of rabbit pasteurellosis.

Surviving winter on the Qinghai-Tibetan Plateau: Pikas suppress energy demands and exploit yak feces to survive winter.

The Qinghai-Tibetan Plateau, with low precipitation, low oxygen partial pressure, and temperatures routinely dropping below -30 °C in winter, presents several physiological challenges to its fauna. Yet it is home to many endemic mammalian species, including the plateau pika (Ochotona curzoniae). How these small animals that are incapable of hibernation survive the winter is an enigma. Measurements of daily energy expenditure (DEE) using the doubly labeled water method show that pikas suppress their DEE during winter. At the same body weight, pikas in winter expend 29.7% less than in summer, despite ambient temperatures being approximately 25 °C lower. Combined with resting metabolic rates (RMRs), this gives them an exceptionally low metabolic scope in winter (DEE/RMRt = 1.60 ± 0.30; RMRt is resting metabolic rate at thermoneutrality). Using implanted body temperature loggers and filming in the wild, we show that this is achieved by reducing body temperature and physical activity. Thyroid hormone (T3 and T4) measurements indicate this metabolic suppression is probably mediated via the thyroid axis. Winter activity was lower at sites where domestic yak (Bos grunniens) densities were higher. Pikas supplement their food intake at these sites by eating yak feces, demonstrated by direct observation, identification of yak DNA in pika stomach contents, and greater convergence in the yak/pika microbiotas in winter. This interspecific coprophagy allows pikas to thrive where yak are abundant and partially explains why pika densities are higher where domestic yak, their supposed direct competitors for food, are more abundant.

Parasitological and molecular investigation of consequences of raw meat feeding (BARF) in dogs and cats: implications for other pets living nearby.

Considering the original nature of carnivorism among dogs and cats, nowadays these pets are increasingly fed BARF (Biologically Appropriate Raw Food/Bone And Raw Food) diet to improve their health conditions. However, this diet may also carry health risks, such as vitamin or mineral deficiencies, and infection with pathogens including parasites. In our study, fecal samples of 89 pet animals kept on BARF diet were subjected to coprological examination followed by molecular analyses. Six of them shed eggs of Dicrocoelium dendriticum. This result was confirmed with PCR and sequencing, and in one case, the DNA of Fasciola hepatica was also demonstrated. In addition, oocysts of Cystoisospora canis, a Cystoisospora ohioensis-like sp. and Eimeria stiedai, as well as sporocysts of a Sarcocystis sp. were also detected. All samples were negative for Neospora caninum and Toxoplasma gondii. In conclusion, no evidence was found for the infection of BARF-fed dogs and cats with parasites that are usually associated with this diet and considered as clinico-pathological risk factors for these pets themselves (e.g., N. caninum, T. gondii). However, fluke eggs (probably originating from ruminants) and oocysts of E. stiedai (from rabbit liver in the food) were demonstrated as pseudoparasites. These species are usually not considered among parasite-associated risks of BARF-feeding, implying that other animals living near BARF-fed pets are neglected in this context. However, where intermediate hosts of D. dendriticum occur in urban areas, BARF-feeding may indirectly affect later other dogs and cats. It was also shown here that BARF-feeding may contribute to the contamination of the environment with E. stiedai oocysts, thus increasing the risks of biliary coccidiosis in nearby living pet rabbits that would otherwise not have access to oocysts of E. stiedai.

Apoptotic Cell Death in an Animal Model of Virus-Induced Acute Liver Failure-Observations during Lagovirus europaeus/GI.2 Infection.

Lagovirus europaeus/GI.2 causes severe and highly fatal Rabbit Hemorrhagic Disease (RHD). Because of its characteristics, this infection is used as an animal model for acute liver failure (ALF). Apoptosis is one of the key processes underlying ALF and has been described as one of the mechanisms of RHD pathogenesis. Apoptotic cell death has been quite well characterized in infection with different variants of GI.1 strains, but so far, the GI.2 genotype has not been widely studied. In this study, we performed an evaluation of apoptotic cell death in hepatocytes of rabbits infected with Lagovirus europaeus/GI.2. We analyzed the expression of genes involved in apoptotic cell death by real-time PCR and performed immunohistochemical (IHC) assays. We showed a significant increase in the expression of caspase-3 and the proapoptotic Bax and anti-apoptotic Bcl-2 in infected animals. In addition, we recorded increased Bax/Bcl-2 ratios. IHC analyses showed the presence of morphological signs of apoptosis in the hepatocytes of infected rabbits. Our results indicate that caspase-3 and proteins from the Bcl-2 families play a key role in apoptosis induced by Lagovirus europaeus/GI.2 infection.

Downregulation of Serotonergic System Components in an Experimentally Induced Cryptorchidism in Rabbits.

Cryptorchidism (CO) or undescended testes is defined as the failure of one or both testes to be positioned inside the scrotum. Typically, cryptorchidism is detected at birth or shortly thereafter, and in humans, it is considered to be part of the testicular dysgenesis syndrome (TDS), a complex pathology regarding the male reproductive system that apparently involves the interaction of both genetic and environmental harmful factors, mainly during embryonic development. Serotonin (5-HT) is an ancient molecule that participates in a broad range of body functions, and in recent years, its importance in reproduction has started to be elucidated. In male pathologies such as infertility, varicocele, erectile dysfunction, and primary carcinoid tumors, an increase in 5-HT concentration or its metabolites in the blood, semen, and urine has been directly related; nevertheless, the role of 5-HT in CO remains unknown. In the present work, our goal was to answer two important questions: (1) whether some serotonergic system components are present in adult male Oryctolagus cuniculus (chinchilla rabbit) and (2) if there are changes in their expression in an experimental model of CO. Using histological, molecular, and biochemical approaches, we found the presence of some serotonergic system components in the adult chinchilla rabbit, and we demonstrated that its expression is downregulated after CO was pharmacologically induced. Although we did not test the role of 5-HT in the etiology of CO, our results suggest that this indoleamine could be important for the regulation of steroidogenesis and spermatogenesis processes in the chinchilla rabbit during adulthood. Finally, in parallel experimental series, we found downregulation of kynurenine concentration in COI rabbits when compared to control ones, suggesting that CO could be affecting the kynurenine pathway and probably testicular immune privilege which in turn could lead to infertility/sterility conditions in this disorder.

Self-Assembling E2-Based Nanoparticles Improve Vaccine Thermostability and Protective Immunity against CSFV.

Classical swine fever virus (CSFV) is a highly contagious pathogen causing significant economic losses in the swine industry. Conventional inactivated or attenuated live vaccines for classical swine fever (CSF) are effective but face biosafety concerns and cannot distinguish vaccinated animals from those infected with the field virus, complicating CSF eradication efforts. It is noteworthy that nanoparticle (NP)-based vaccines resemble natural viruses in size and antigen structure, and offer an alternative tool to circumvent these limitations. In this study, we developed an innovative vaccine delivery scaffold utilizing self-assembled mi3 NPs, which form stable structures carrying the CSFV E2 glycoprotein. The expressed yeast E2-fused protein (E2-mi3 NPs) exhibited robust thermostability (25 to 70 °C) and long-term storage stability at room temperature (25 °C). Interestingly, E2-mi3 NPs made with this technology elicited enhanced antigen uptake by RAW264.7 cells. In a rabbit model, the E2-mi3 NP vaccine against CSFV markedly increased CSFV-specific neutralizing antibody titers. Importantly, it conferred complete protection in rabbits challenged with the C-strain of CSFV. Furthermore, we also found that the E2-mi3 NP vaccines triggered stronger cellular (T-lymphocyte proliferation, CD8+ T-lymphocytes, IFN-γ, IL-2, and IL-12p70) and humoral (CSFV-specific neutralizing antibodies, CD4+ T-lymphocytes, and IL-4) immune responses in pigs than the E2 vaccines. To sum up, these structure-based, self-assembled mi3 NPs provide valuable insights for novel antiviral strategies against the constantly infectious agents.

Cornelian Cherry (Cornus mas L.) Fruit Extract Lowers SREBP-1c and C/EBPα in Liver and Alters Various PPAR-α, PPAR-γ, LXR-α Target Genes in Cholesterol-Rich Diet Rabbit Model.

Cornelian cherry (Cornus mas L.) fruits, abundant in iridoids and anthocyanins, are natural products with proven beneficial impacts on the functions of the cardiovascular system and the liver. This study aims to assess and compare whether and to what extent two different doses of resin-purified cornelian cherry extract (10 mg/kg b.w. or 50 mg/kg b.w.) applied in a cholesterol-rich diet rabbit model affect the levels of sterol regulatory element-binding protein 1c (SREBP-1c) and CCAAT/enhancer binding protein α (C/EBPα), and various liver X receptor-α (LXR-α), peroxisome proliferator-activated receptor-α (PPAR-α), and peroxisome proliferator-activated receptor-γ (PPAR-γ) target genes. Moreover, the aim is to evaluate the resistive index (RI) of common carotid arteries (CCAs) and aortas, and histopathological changes in CCAs. For this purpose, the levels of SREBP-1c, C/EBPα, ATP-binding cassette transporter A1 (ABCA1), ATP-binding cassette transporter G1 (ABCG1), fatty acid synthase (FAS), endothelial lipase (LIPG), carnitine palmitoyltransferase 1A (CPT1A), and adiponectin receptor 2 (AdipoR2) in liver tissue were measured. Also, the levels of lipoprotein lipase (LPL), visceral adipose tissue-derived serine protease inhibitor (Vaspin), and retinol-binding protein 4 (RBP4) in visceral adipose tissue were measured. The RI of CCAs and aortas, and histopathological changes in CCAs, were indicated. The oral administration of the cornelian cherry extract decreased the SREBP-1c and C/EBPα in both doses. The dose of 10 mg/kg b.w. increased ABCA1 and decreased FAS, CPT1A, and RBP4, and the dose of 50 mg/kg b.w. enhanced ABCG1 and AdipoR2. Mitigations in atheromatous changes in rabbits' CCAs were also observed. The obtained outcomes were compared to the results of our previous works. The beneficial results confirm that cornelian cherry fruit extract may constitute a potentially effective product in the prevention and treatment of obesity-related disorders.

Positive role of plateau pika (Ochotona coronae) on environmental quality at low and moderate density on the Tibetan plateau: Evidence from a meta-analysis.

The roles of plateau pika (Ochotona coronae) in the Tibetan Plateau are often controversial, because it is often regarded as a destructive pest or an ecosystem engineer. Here a meta-analysis using 72 paired observations was conducted to examine whether the impacts of plateau pika on environmental quality (i.e., plant and soil properties) depend on population density in the Tibetan Plateau. Pika population density was used as a proxy for disturbance intensity. The pika disturbance intensity was divided into five groups based on the number of burrows, including low disturbance intensity (LD) (9-30 burrows per ha), medium disturbance intensity (MD) (31-100 burrows per ha), high disturbance intensity (HD) (101-170 burrows per ha), extreme disturbance intensity (ED) (171-240 burrows per ha) and uncontrolled (or excessive) disturbance intensity (UD) (>241 burrows per ha). Given that sample sizes in some of the groups are small (especially for the HD), we further pooled the disturbance groups including the LD-MD and HD-UD. Overall, relative to control (i.e., no disturbing), there was a great increase (80.3%) in aboveground biomass under the LD-MD, whereas a decrease of 41.1% occurred under the HD-UD. At the same time, plant coverage, species richness, height, and belowground biomass greatly decreased only in the HD-UD. Furthermore, the effect size of plant coverage, species richness, and aboveground biomass also declined with pika burrow density significantly. With regard to soil properties, there was a significant increase in soil organic carbon, ammonium nitrogen, and soil organic carbon stock under the LD-MD, whereas a decrease under the HD-UD. In addition, soil total nitrogen, total potassium, and nitrate nitrogen increased at the LD-MD and HD-UD. Nevertheless, the effect size of these soil properties (with >20 observations) was not related to pika burrow density. In summary, there is an implication that the low and moderate disturbance of pikas is beneficial to maintain and promote ecosystem functioning in the Tibetan grasslands. In the future pikas' eradication policy should be reconsidered in alpine grassland management.

Novel Rickettsia and host records for argasid ticks, including Alveonasus cooleyi, on wild mammals in Baja California, Mexico.

We conducted surveillance of mammals to investigate their associations with argasid ticks and tick-borne pathogens. During 2021, a total of 20 wild carnivores and 57 lagomorphs were sampled, and 39 argasid ticks belonging to two species were collected. All mammals and ticks were tested by molecular assays to detect Borrelia and Rickettsia infections. Nine ticks identified as Otobius megnini were collected from two coyotes (Canis latrans) and 30 Alveonasus cooleyi (McIvor 1941) were collected from six bobcats (Lynx rufus) and one rabbit (Sylvilagus auduboni). We detected Rickettsia spp. DNA in 21 of the 27 (77.8%) tested Av. cooleyi and none of the O. megnini. No ticks were PCR-positive for borreliae and all mammals were PCR-negative for both pathogen genera. Phylogenetic analysis based on gltA, htrA, and 16 S rRNA targets revealed that all rickettsiae from Av. cooleyi clustered with ancestral group rickettsiae, likely representing a novel species of possibly endosymbiotic Rickettsia. The significance of Av. cooleyi and the newly identified Rickettsia sp. to the health of wildlife is unknown, and further work is indicated to determine whether they may be relevant to public health or carnivore conservation.

Rabbits (Oryctolagus cuniculus) increase caecal calcium absorption at increasing dietary calcium levels.

Hindgut fermenting herbivores from different vertebrate taxa, including tortoises, and among mammals some afrotheria, perissodactyla incl. equids, several rodents as well as lagomorphs absorb more calcium (Ca) from the digesta than they require, and excrete the surplus via urine. Both proximate and ultimate causes are elusive. It was suggested that this mechanism might ensure phosphorus availability for the hindgut microbiome by removing potentially complex-building Ca from the digesta. Here we use Ussing chamber experiments to show that rabbits (Oryctolagus cuniculus) maintained on four different diets (six animals/diet) increase active Ca absorption at increasing Ca levels. This contradicts the common assumption that at higher dietary levels, where passive uptake should be more prevalent, active transport can relax and hence supports the deliberate removal hypothesis. In the rabbits, this absorption was distinctively higher in the caecum than in the duodenum, which is unexpected in mammals. Additional quantification of the presence of two proteins involved in active Ca absorption (calbindin-D9K CB; vitamin D receptor, VDR) showed higher presence with higher dietary Ca. However, their detailed distribution across the intestinal tract and the diet groups suggests that other factors not investigated in this study must play major roles in Ca absorption in rabbits. Investigating strategies of herbivores to mitigate potential negative effects of Ca in the digesta on microbial activity and growth might represent a promising area of future research.

Molecular phenotyping uncovers differences in basic housekeeping functions among closely related species of hares (Lepus spp., Lagomorpha: Leporidae).

Speciation is a fundamental evolutionary process, which results in genetic differentiation of populations and manifests as discrete morphological, physiological and behavioural differences. Each species has travelled its own evolutionary trajectory, influenced by random drift and driven by various types of natural selection, making the association of genetic differences between the species with the phenotypic differences extremely complex to dissect. In the present study, we have used an in vitro model to analyse in depth the genetic and gene regulation differences between fibroblasts of two closely related mammals, the arctic/subarctic mountain hare (Lepus timidus Linnaeus) and the temperate steppe-climate adapted brown hare (Lepus europaeus Pallas). We discovered the existence of a species-specific expression pattern of 1623 genes, manifesting in differences in cell growth, cell cycle control, respiration, and metabolism. Interspecific differences in the housekeeping functions of fibroblast cells suggest that speciation acts on fundamental cellular processes, even in these two interfertile species. Our results help to understand the molecular constituents of a species difference on a cellular level, which could contribute to the maintenance of the species boundary.

Host phylogeny and functional traits differentiate gut microbiomes in a diverse natural community of small mammals.

Differences in the bacterial communities inhabiting mammalian gut microbiomes tend to reflect the phylogenetic relatedness of their hosts, a pattern dubbed phylosymbiosis. Although most research on this pattern has compared the gut microbiomes of host species across biomes, understanding the evolutionary and ecological processes that generate phylosymbiosis requires comparisons across phylogenetic scales and under similar ecological conditions. We analysed the gut microbiomes of 14 sympatric small mammal species in a semi-arid African savanna, hypothesizing that there would be a strong phylosymbiotic pattern associated with differences in their body sizes and diets. Consistent with phylosymbiosis, microbiome dissimilarity increased with phylogenetic distance among hosts, ranging from congeneric sets of mice and hares that did not differ significantly in microbiome composition to species from different taxonomic orders that had almost no gut bacteria in common. While phylosymbiosis was detected among just the 11 species of rodents, it was substantially weaker at this scale than in comparisons involving all 14 species together. In contrast, microbiome diversity and composition were generally more strongly correlated with body size, dietary breadth, and dietary overlap in comparisons restricted to rodents than in those including all lineages. The starkest divides in microbiome composition thus reflected the broad evolutionary divergence of hosts, regardless of body size or diet, while subtler microbiome differences reflected variation in ecologically important traits of closely related hosts. Strong phylosymbiotic patterns arose deep in the phylogeny, and ecological filters that promote functional differentiation of cooccurring host species may disrupt or obscure this pattern near the tips.

Prolonged cyclical loading induces Haversian remodeling in mandibles of growing rabbits.

Bone adaptation to mechanical loading happens predominantly via modeling and remodeling, but the latter is poorly understood. Haversian remodeling (cortical bone replacement resulting in secondary osteons) is thought to occur in regions of low strain as part of bone maintenance or high strain in response to microdamage. However, analyses of remodeling in primates have revealed an unappreciated association with the number of daily load cycles. We tested this relationship by raising 30 male domestic rabbits (Oryctolagus cuniculus) on disparate diets from weaning to adulthood (48 weeks), facilitating a naturalistic perspective on mandibular bone adaptation. A control group consumed only rabbit pellets and an 'overuse' group ate hay in addition to pellets. To process hay, which is tougher and stiffer, rabbits increase chewing investment and duration without increasing bite force (i.e. corpus mean peak strain is similar for the two foods). Corpus remodeling in overuse rabbits was ∼1.5 times that of controls, measured as osteon population density and percentage Haversian bone. In the same subjects, there was a significant increase in overuse corpus bone formation (ratio of cortical area to cranial length), consistent with previous reports on the same dietary manipulation and bone formation in rabbits. This is the first evidence that both modeling and remodeling are simultaneously driven by the number of load cycles, independent of strain magnitude. This novel finding provides unique data on the feeding apparatus, challenges traditional thought on Haversian remodeling, and highlights the need for experimental studies of skeletal adaptation that examine mechanical factors beyond strain magnitude.

Establishment of a secondary infection laboratory model of Echinococcus shiquicus metacestode using BALB/c mice and Mongolian jirds (Meriones unguiculatus).

Echinococcus shiquicus is peculiar to the Qinghai­Tibet plateau of China. Research on this parasite has mainly focused on epidemiological surveys and life cycle studies. So far, limited laboratory studies have been reported. Here, experimental infection of E. shiquicus metacestode in BALB/c mice and Mongolian jirds (Meriones unguiculatus) was carried out to establish alternative laboratory animal models. Intraperitoneal inoculation of metacestode material containing protoscoleces (PSCs) obtained from infected plateau pikas were conducted on BALB/c mice. Furthermore, metacestode material without PSCs deriving from infected BALB/c mice was intraperitoneally inoculated to Mongolian jirds. Experimental animals were dissected for macroscopic and histopathological examination. The growth of cysts in BALB/c mice was infiltrative, and they invaded the murine entire body. Most of the metacestode cysts were multicystic, but a few were unilocular. The cysts contained sterile vesicles, which had no PSCs. The metacestode materials were able to successfully infect new mice. In the jirds model, E. shiquicus cysts were typically formed freely in the peritoneal cavity; the majority of these cysts were free while a small portion adhered loosely to nearby organs. The proportion of fertile cysts was high, and contained many PSCs. The PSCs produced in Mongolian jirds also successfully infected new ones, which confirms that jirds can serve as an alternative experimental intermediate host. In conclusion, a laboratory animal infection was successfully established for E. shiquicus using BALB/c mice and Mongolian jirds. These results provide new models for the in-depth study of Echinococcus metacestode survival strategy, host interactions and immune escape mechanism.

Attenuation of pathogenesis of Eimeria stiedae sporulated oocysts using Egyptian alginate propolis nanoparticles.

BACKGROUND: Coccidiosis is a costly and widespread infectious disease that affects mammals and causes huge losses for the global rabbit meat industry. This study evaluated the potency of Egyptian alginate propolis nanoparticles (NPs) in attenuating the infectivity of Eimeria stiedae sporulated oocysts. The gelification method was used to prepare alginate propolis NPs, which were then characterized using a transmission electron microscope and zeta potential analysis. RESULTS: The results revealed that the zeta potential of the prepared alginate propolis NPs increased from - 60.60 ± 9.10 mV to -72.26 ± 6.04 mV. The sporulated oocysts were treated with 50 mg/mL of the alginate propolis NPs. Thereafter, the treated oocysts were tested for their ability to infect rabbits. The rabbits were divided into three groups: the healthy control (G1) group, the infected control (G2) group, and the treated oocyst-infected (G3) group. The rabbits were sacrificed 43 days post-infection (dpi). The infectivity of the oocysts was assessed. The treated oocyst-infected rabbits exhibited slight abdominal distension and dullness symptoms. The G3 group had no oocyst output, with a 100% reduction from 41 dpi until the end of the experiment. Immunologically, the IgG level of the G2 group gradually increased (p ≤ 0.05) much more than that of the G3 group. The IL-12 level in the G3 group significantly increased from 16 dpi until the end of the experiment, nearly reaching the level in healthy animals. Decreased CD4+ and CD8+ immunolabelling was observed in the liver sections of the group infected with the alginate propolis NP-treated oocysts, and there was a remarkable improvement in the histopathological parameters. CONCLUSIONS: These data indicate that Alg propolis NPs are sufficient to reduce the infectivity of E. stiedae oocysts.