The effectiveness of using giant panda as a surrogate for protecting sympatric species.

The use of umbrella species to promote biodiversity conservation is practiced worldwide. The giant panda (Ailuropoda melanoleuca) an iconic species for world wildlife conservation, that inhabits regions with significant biodiversity. Given that the functions at wildlife of different trophic levels and in different body size groups are different within the ecosystem, it is unknown whether those groups of wildlife co-occurring with giant pandas are each likewise protected. To examine the umbrella effect of giant pandas on sympatric species, we used an extensive dataset of wildlife from more than 78% of giant panda habitats. We analysed the changes in distribution for four wildlife categories (large carnivores, large herbivores, medium carnivores and medium herbivores) using a generalized linear mixed model, and the underlying driving factors using binomial logistic regression models. Changes in forests in giant panda habitats were evaluated using Fragstats. The results have shown that the counts of herbivores and medium carnivores increased significantly during the decade. However, those of large carnivores significantly declined. Forest cover and nature reserves showed significant and positive effects on wildlife in 2001 and 2011, while the human population had significant and negative impacts on the herbivores and carnivores. Our results have also suggested that there has been a slight alleviation in forest fragmentation in areas unaffected by earthquakes. We concluded that the umbrella strategy of using the giant panda as an umbrella species achieved partial success by promoting the recovery of herbivores and medium carnivores. Meanwhile, this has indicated that the strategy was not sufficient for large carnivores, and therefore not enough for local ecosystems, given the critical role of large carnivores. We have suggested integrating habitat patches, controlling human disturbance, and preparing for potential human-wildlife conflict management in the Giant Panda National Park to restore large carnivore populations and maintain ecosystem functioning.

Hippocampal delivery of neurotrophic factor-α1/carboxypeptidase E gene prevents neurodegeneration, amyloidosis, memory loss in Alzheimer's Disease male mice.

Alzheimer's Disease (AD) is a prevalent neurodegenerative disease characterized by tau hyperphosphorylation, Aß1-42 aggregation and cognitive dysfunction. Therapeutic agents directed at mitigating tau aggregation and clearing Aß1-42, and delivery of growth factor genes (BDNF, FGF2), have ameliorated cognitive deficits, but these approaches did not prevent or stop AD progression. Here we report that viral-(AAV) delivery of Neurotrophic Factor-α1/Carboxypeptidase E (NF-α1/CPE) gene in hippocampus at an early age prevented later development of cognitive deficits as assessed by Morris water maze and novel object recognition assays, neurodegeneration, and tau hyperphosphorylation in male 3xTg-AD mice. Additionally, amyloid precursor protein (APP) expression was reduced to near non-AD levels, and insoluble Aß1-42 was reduced significantly. Pro-survival proteins: mitochondrial Bcl2 and Serpina3g were increased; and mitophagy inhibitor Plin4 and pro-inflammatory protein Card14 were decreased in AAV-NF-α1/CPE treated versus untreated AD mice. Thus NF-α1/CPE gene therapy targets many regulatory components to prevent cognitive deficits in 3xTg-AD mice and has implications as a new therapy to prevent AD progression by promoting cell survival, inhibiting APP overexpression and tau hyperphosphorylation.

Characterization of serotonin-5-HTR1E signaling pathways and its role in cell survival.

5-Hydroxytryptamine receptor 1E (5-HTR1E) is reported to activate cyclic AMP (cAMP) and extracellular-signal related kinases (ERK) pathways via its ligands and binding partners, but the detailed mechanism underlying the serotonin-induced 5-HTR1E signaling is still not known. In the present study, we determined the cellular regulators of ERK and cAMP signaling pathways in response to serotonin-induced 5-HTR1E activation in 5-HTR1E overexpressing HEK293 cells. We found that Pertussis Toxin (PTX) treatment completely reversed the effect of serotonin-5-HTR1E mediated signaling on cAMP and ERK pathways, confirming the involvement of a Gαi-linked cascade. We also observed that Gßγ and Gq were not associated with 5-HTR1E activation, while blocking protein kinase A (PKA) inhibited ERK signaling only, and had no effect on cAMP. Additionally, serotonin-stimulated ERK1/2 phosphorylation was similar in 5-HTR1E overexpressing, ß-arrestin-deficient HEK293 cells and is solely dependent on G protein signaling. siRNA mediated gene knockdown studies in SH-SY5Y cells revealed that the inhibition of 5-HTR1E reduced the expression of cMyc, Cyclin D1, Cyclin E and BCL2 genes which are related to cell cycle regulation and survival. MTT assays showed that 5-HTR1E knockdown in SHSY-5Y and U118 cells inhibited cell survival significantly. In addition to the signaling mechanism, we also performed RNA-seq analysis in 5-HTR1E overexpressing HEK293 cells and found that 5-HTR1E can regulate the expression of Receptor activity modifying protein 1 (RAMP1), Nuclear receptor 1 (NR4A1) and other Cyclin genes. These findings indicate that serotonin interaction with 5-HTR1E receptor simultaneously activates cAMP and ERK pathway in HEK293 cells and its expression is important for cell survival.

Graphene oxide as a multi-functional additive for compatilizer, enhancer, and barrier in ethylene vinyl alcohol copolymer/aramid pulp composites.

To improve the thermal, mechanical, and barrier properties of ethylene vinyl alcohol copolymer (EVOH)/aramid pulp (AP), graphene oxide (GO) was used as a compatilizer, enhancer, and barrier to fabricate EVOH-based composites. The results showed that graphene oxide serves as an ideal compatilizer to reinforce the interfacial action between the EVOH matrix and aramid pulp. The EVOH/AP/GO composite presented the best combination of thermal stability, tensile strength, oxygen barrier, and heat deformation temperature by adding only 1 wt% graphene oxide, compared to those of pure EVOH. Moreover, both scanning electron microscopy (SEM) and polarized optical microscopy (POM) photographs demonstrated that the aramid pulp dispersed homogeneously into the EVOH resin with the addition of 1 wt% graphene oxide. Our work provides a novel and facile way for producing a prominent EVOH-based composite, which can be potentially used in packaging fields in the future.

Characterization of serotonin-5-HTR1E signaling pathways and its role in cell survival.

5-Hydroxy tryptamine receptor 1E (5-HTR1E) is reported to activate cAMP and ERK pathways via its ligands and binding partners, but the detailed mechanism underlying the serotonin induced 5-HTR1E signaling is still not known. In the present study, we determined the cellular regulators of ERK and cAMP signaling pathways in response to serotonin induced 5-HTR1E activation in 5-HTR1E overexpressing HEK293 cells. We found that Pertussis Toxin (PTX) treatment completely reversed the effect of serotonin-5-HTR1E mediated signaling on cAMP and ERK pathways, confirming the involvement of a Gαi-linked cascade. We also observed that Gßγ and Gq were not associated with 5-HTR1E activation, while blocking PKA inhibited ERK signaling only, and had no effect on cAMP. Additionally, serotonin-stimulated ERK1/2 phosphorylation was similar in 5-HTR1E overexpressing, ß-arrestin-deficient HEK293 cells and is solely dependent on G protein signaling. siRNA mediated gene knockout studies in SH-SY5Y cells revealed that the inhibition of 5-HTR1E reduced the expression of cMyc, Cyclin D1, Cyclin E and BCL2 genes which are related to cell cycle regulation and survival. MTT assays showed that 5-HTR1E knockdown in SHSY-5Y and U118 cells inhibited cell survival significantly. In addition to the signaling mechanism, we also performed RNA-seq analysis in 5-HTR1E overexpressing HEK293 cells and found that 5-HTR1E can regulate the expression of Receptor activity modifying protein 1 ( RAMP1 ), Nuclear receptor 1 ( NR4A1 ) and other Cyclin genes. These findings indicate that serotonin interaction with 5-HTR1E receptor simultaneously activates cAMP and ERK pathway in HEK293 cells and its expression is important for cell survival.

Carboxypeptidase E and its splice variants: Key regulators of growth and metastasis in multiple cancer types.

Mechanisms driving tumor growth and metastasis are complex, and involve the recruitment of many genes working in concert with each other. The tumor is characterized by the expression of specific sets of genes depending on its environment. Here we review the role of the carboxypeptidase E (CPE) gene which has been shown to be important in driving growth, survival and metastasis in many cancer types. CPE was first discovered as a prohormone processing enzyme, enriched in endocrine tumors, and later found to be expressed and secreted from many epithelial-derived tumors and cancer cell lines. Numerous studies have shown that besides wild-type CPE, a N-terminal truncated splice variant form of CPE (CPE-ΔN) has been cloned and found to be highly expressed in malignant tumors and cell lines derived from prostate, breast, liver and lung cancers and gliomas. The mechanisms of action of CPE and the splice variant in promoting tumor growth and metastasis in different cancer types are discussed. Mechanistically, secreted CPE activates the Erk/wnt pathways, while CPE-ΔN interacts with HDACs in a protein complex in the nucleus, to recruit various cell cycle genes and metastatic genes, respectively. Clinical studies suggest that CPE and CPE-ΔN mRNA and protein are potential diagnostic and prognostic biomarkers for multiple cancer types, assayed using solid tumors and secreted serum exosomes. CPE has been shown to be a therapeutic target for multiple cancer types. CPE/CPE-ΔN siRNA transported via exosomes and taken up by recipient high metastatic cancer cells, suppressed growth and proliferation of these cells. Thus future studies, delivering CPE/CPE-ΔN siRNA, perhaps via exosomes, to the tumor could be a novel treatment approach to suppress tumor growth and metastasis.

Landscape-scale giant panda conservation based on metapopulations within China's national park system.

Historically, giant panda conservation in China has been compromised by disparate management of protected areas. It is thus crucial to address how giant panda populations can be managed cohesively on a landscape scale, an opportunity offered by China's newly established Giant Panda National Park. Here, we evaluated giant panda populations in a metapopulation context, based on range-wide data from the Fourth National Giant Panda Survey. We delineated metapopulations by geographic range, relative abundance, and relative density and assessed the extent of human disturbance each metapopulation faced. We found density-dependent and disturbance-influenced effects on habitat selection across metapopulations. We determined the main effects faced by each metapopulation regarding area sensitivity, population size, intraspecific competition, and disturbance. To enhance the landscape-scale conservation of giant pandas and various other wildlife across China's national park system, we propose that metapopulation management incorporates population status along with density-dependent and disturbance-related effects on habitat selection.

Exosomal Carboxypeptidase E (CPE) and CPE-shRNA-Loaded Exosomes Regulate Metastatic Phenotype of Tumor Cells.

BACKGROUND: Exosomes promote tumor growth and metastasis through intercellular communication, although the mechanism remains elusive. Carboxypeptidase E (CPE) supports the progression of different cancers, including hepatocellular carcinoma (HCC). Here, we investigated whether CPE is the bioactive cargo within exosomes, and whether it contributes to tumorigenesis, using HCC cell lines as a cancer model. METHODS: Exosomes were isolated from supernatant media of cancer cells, or human sera. mRNA and protein expression were analyzed using PCR and Western blot. Low-metastatic HCC97L cells were incubated with exosomes derived from high-metastatic HCC97H cells. In other experiments, HCC97H cells were incubated with CPE-shRNA-loaded exosomes. Cell proliferation and invasion were assessed using MTT, colony formation, and matrigel invasion assays. RESULTS: Exosomes released from cancer cells contain CPE mRNA and protein. CPE mRNA levels are enriched in exosomes secreted from high- versus low-metastastic cells, across various cancer types. In a pilot study, significantly higher CPE copy numbers were found in serum exosomes from cancer patients compared to healthy subjects. HCC97L cells, treated with exosomes derived from HCC97H cells, displayed enhanced proliferation and invasion; however, exosomes from HCC97H cells pre-treated with CPE-shRNA failed to promote proliferation. When HEK293T exosomes loaded with CPE-shRNA were incubated with HCC97H cells, the expression of CPE, Cyclin D1, a cell-cycle regulatory protein and c-myc, a proto-oncogene, were suppressed, resulting in the diminished proliferation of HCC97H cells. CONCLUSIONS: We identified CPE as an exosomal bioactive molecule driving the growth and invasion of low-metastatic HCC cells. CPE-shRNA loaded exosomes can inhibit malignant tumor cell proliferation via Cyclin D1 and c-MYC suppression. Thus, CPE is a key player in the exosome transmission of tumorigenesis, and the exosome-based delivery of CPE-shRNA offers a potential treatment for tumor progression. Notably, measuring CPE transcript levels in serum exosomes from cancer patients could have potential liquid biopsy applications.

Novel interaction between neurotrophic factor-α1/carboxypeptidase E and serotonin receptor, 5-HTR1E, protects human neurons against oxidative/neuroexcitotoxic stress via ß-arrestin/ERK signaling.

Protecting neurons from death during oxidative and neuroexcitotoxic stress is key for preventing cognitive dysfunction. We uncovered a novel neuroprotective mechanism involving interaction between neurotrophic factor-α1 (NF-α1/carboxypeptidase E, CPE) and human 5-HTR1E, a G protein-coupled serotonin receptor with no previously known neurological function. Co-immunoprecipitation and pull-down assays confirmed interaction between NFα1/CPE and 5-HTR1E and 125I NF-α1/CPE-binding studies demonstrated saturable, high-affinity binding to 5-HTR1E in stably transfected HEK293 cells (Kd = 13.82 nM). Treatment of 5-HTR1E stable cells with NF-α1/CPE increased pERK 1/2 and pCREB levels which prevented a decrease in pro-survival protein, BCL2, during H2O2-induced oxidative stress. Cell survival assay in ß-arrestin Knockout HEK293 cells showed that the NF-α1/CPE-5-HTR1E-mediated protection against oxidative stress was ß-arrestin-dependent. Molecular dynamics studies revealed that NF-α1/CPE interacts with 5-HTR1E via 3 salt bridges, stabilized by several hydrogen bonds, independent of the serotonin pocket. Furthermore, after phosphorylating the C-terminal tail and intracellular loop 3 (ICL3) of NF-α1/CPE-5-HTR1E, it recruited ß-arrestin1 by forming numerous salt bridges and hydrogen bonds to ICL2 and ICL3, leading to activation of ß-arrestin1. Immunofluorescence studies showed 5-HTR1E and NF-α1/CPE are highly expressed and co-localized on cell surface of human hippocampal neurons. Importantly, knock-down of 5-HTR1E in human primary neurons diminished the NF-α1/CPE-mediated protection of these neurons against oxidative stress and glutamate neurotoxicity-induced cell death. Thus, NF-α1/CPE uniquely interacts with serotonin receptor 5-HTR1E to activate the ß-arrestin/ERK/CREB/BCL2 pathway to mediate stress-induced neuroprotection.

Fly-over phylogeny across invertebrate to vertebrate: The giant panda and insects share a highly similar gut microbiota.

Many studies highlight that host phylogeny and diet are the two main factors influencing the animal gut microbiota. However, the internal mechanisms driving the evolution of animal gut microbiota may be more complex and complicated than we previously realized. Here, based on a large-scale meta-analysis of animal gut microbiota (16 s RNA gene data from approximately 1,800 samples; 108 metagenomes) across a wide taxonomic range of hosts, from invertebrate to vertebrate, we found high similarity in the gut microbial community (high proportion of Gammaproteobacteria (Pseudomonas)) of invertebrate insects and vertebrate bamboo-eating pandas (giant panda and red panda), which might be associated their plant-eating behavior and the presence of oxygen in the intestinal tract. A Pseudomonas strain-level analysis using 108 metagenomes further revealed that the response to either host niches or selection by the host might further lead to host-specific strains (or sub-strains) among the different hosts congruent with their evolutionary history. In this study, we uncovered new insights into the current understanding of the evolution of animals and their gut microbiota.

Neurotrophic factor-α1, a novel tropin is critical for the prevention of stress-induced hippocampal CA3 cell death and cognitive dysfunction in mice: comparison to BDNF.

Stress leads to brain pathology including hippocampal degeneration, cognitive dysfunction, and potential mood disorders. Hippocampal CA3, a most stress-vulnerable region, consists of pyramidal neurons that regulate cognitive functions e.g. learning and memory. These CA3 neurons express high levels of the neuroprotective protein, neurotrophic factor-α1 (NF-α1), also known as carboxypeptidase E (CPE), and receive contacts from granule cell projections that release BDNF which has neuroprotective activity. Whether NF-α1-CPE and/or BDNF are critical in protecting these CA3 neurons against severe stress-induced cell death is unknown. Here we show that social combined with the physical stress of maternal separation, ear tagging, and tail snipping at weaning in 3-week-old mice lacking NF-α1-CPE, led to complete hippocampal CA3 degeneration, despite having BDNF and active phosphorylated TrkB receptor levels similar to WT animals. Mice administered TrkB inhibitor, ANA12 which blocked TrkB phosphorylation showed no degeneration of the CA3 neurons after the weaning stress paradigm. Furthermore, transgenic knock-in mice expressing CPE-E342Q, an enzymatically inactive form, replacing NF-α1-CPE, showed no CA3 degeneration and exhibited normal learning and memory after the weaning stress, unlike NF-α1-CPE-KO mice. Mechanistically, we showed that radio-labeled NF-α1-CPE bound HT22 hippocampal cells in a saturable manner and with high affinity (Kd = 4.37 nM). Subsequently, treatment of the HT22cpe-/- cells with NF-α1-CPE or CPE-E342Q equivalently activated ERK signaling and increased BCL2 expression to protect these neurons against H2O2-or glutamate-induced cytotoxicity. Our findings show that NF-α1-CPE is more critical compared to BDNF in protecting CA3 pyramidal neurons against stress-induced cell death and cognitive dysfunction, independent of its enzymatic activity.

Geographic pattern of antibiotic resistance genes in the metagenomes of the giant panda.

The rise in infections by antibiotic-resistant bacteria poses a serious public health problem worldwide. The gut microbiome of animals is a reservoir for antibiotic resistance genes (ARGs). However, the correlation between the gut microbiome of wild animals and ARGs remains controversial. Here, based on the metagenomes of giant pandas (including three wild populations from the Qinling, Qionglai and Xiaoxiangling Mountains, and two major captive populations from Yaan and Chengdu), we investigated the potential correlation between the constitution of the gut microbiome and the composition of ARGs across the different geographic locations and living environments. We found that the types of ARGs were correlated with gut microbiome composition. The NMDS cluster analysis using Jaccard distance of the ARGs composition of the gut microbiome of wild giant pandas displayed a difference based on geographic location. Captivity also had an effect on the differences in ARGs composition. Furthermore, we found that the Qinling population exhibited profound dissimilarities of both gut microbiome composition and ARGs (the highest proportion of Clostridium and vancomycin resistance genes) when compared to the other wild and captive populations studies, which was supported by previous giant panda whole-genome sequencing analysis. In this study, we provide an example of a potential consensus pattern regarding host population genetics, symbiotic gut microbiome and ARGs. We revealed that habitat isolation impacts the ARG structure in the gut microbiome of mammals. Therefore, the difference in ARG composition between giant panda populations will provide some basic information for their conservation and management, especially for captive populations.

Climate change and landscape-use patterns influence recent past distribution of giant pandas.

Climate change is one of the most pervasive threats to biodiversity globally, yet the influence of climate relative to other drivers of species depletion and range contraction remain difficult to disentangle. Here, we examine climatic and non-climatic correlates of giant panda (Ailuropoda melanoleuca) distribution using a large-scale 30 year dataset to evaluate whether a changing climate has already influenced panda distribution. We document several climatic patterns, including increasing temperatures, and alterations to seasonal temperature and precipitation. We found that while climatic factors were the most influential predictors of panda distribution, their importance diminished over time, while landscape variables have become relatively more influential. We conclude that the panda's distribution has been influenced by changing climate, but conservation intervention to manage habitat is working to increasingly offset these negative consequences.

Author Correction: Flotillin-2 promotes metastasis of nasopharyngeal carcinoma by activating NF-κB and PI3K/Akt3 signaling pathways.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Assessing the Effectiveness of China's Panda Protection System.

Protected areas form the backbone of biodiversity conservation, yet their effectiveness is often not known nor even evaluated [1-3]. China-best known for its record of ecological degradation in the face of rapidly increasing gross domestic product and resource consumption [4]-has in recent years enacted a series of policies and programs to conserve its natural resources. Chief among them is an ambitious protected area system covering 17% of its terrestrial land mass [4, 5]. An important early impetus for the establishment of this reserve system was the protection of the giant panda (Ailuropoda melanoleuca) [5-8]. Using data from two previous large-scale surveys [9, 10] separated by a decade, and including over 50,000 habitat plots, we examined the panda population and habitat trends inside and outside reserves. Despite ambitious ecocompensation programs in panda habitat outside reserves [11-13], the protection provided by reserves reduced most classes of human disturbance compared to outside reserves, and most disturbances decreased through time more strongly inside than outside reserves. Reserves also contained more and increasing suitable panda than found outside reserves [14, 15]. Comparing reserve performance, reserves with increasing older forests and bamboo correlated with increasing panda populations. Together these findings indicate that China's panda reserves have been effective and that they are functioning better over time, conserving more and better habitats and containing more pandas. While China's protected area system still has much room for improvement [4, 5], including to support pandas [16], these findings underscore the progress made in China's nascent environmental movement.

Gap Analysis of Giant Panda Conservation as an Example for Planning China's National Park System.

Protected areas have been the cornerstone for conservation globally [1], but gaps still exist in preserving biodiversity [2]. Meanwhile, areas designated as protected have overlaps between designations and might vary in their management [3, 4]. All three phenomena-coverage gaps, overlapping designations, and disparities in management-are present in China [5, 6]. China plans to establish a national park system for the first time, aiming to reform the existing protected-area system [7-9]. However, there has been no quantitative spatial analysis that can aid the planning of national parks. This study shows how an improved conservation gap analysis can inform the construction of new national parks. Taking the proposed Giant Panda National Park as an example, we analyzed the relationship between panda habitat and the existing protected areas, considering not only de jure designated coverage but also de facto levels of two types of potentially harmful activities (timber extraction and human disturbance). We find that, first, there are coverage gaps in the four mountains comprising the potential national park, and existing protected areas have overlaps between designations. Second, current protected areas have gaps and disparities in terms of restrictions on timber extraction and human disturbance. Third, overlapped designations and less restrictive management appear to have adverse effects on panda protection. On the basis of these results, we propose integrated management under a single national park administration, focusing on the key gaps, which we identify. This study can serve as a reference for the establishment of other national parks in China and the world.

A novel 40kDa N-terminal truncated carboxypeptidase E splice variant: cloning, cDNA sequence analysis and role in regulation of metastatic genes in human cancers.

Carboxypeptidase E (CPE), a prohormone processing enzyme, is a 476- amino acid protein with a signal peptide in its N-terminus and is expressed in the nervous and the endocrine systems. Recent evidence indicate CPE plays various non-enzymatic roles in the endocrine and nervous systems and in various cancers. Besides wild type (WT) CPE, a 40-kDa CPE protein that localizes in the nucleus and cytoplasm has been described in embryonic mouse brain. In this study we have cloned this CPE variant encoding the 40kDa CPE-ΔN protein from human cancer cells. RACE assay and sequence analysis confirmed existence of this CPE variant mRNA, which has 198 nucleotides removed within the first exon and 589 nucleotides from the 3'-UTR, respectively, compared to WT-CPE mRNA. Bioinformatic analysis revealed that this CPE variant mRNA has a shortened open reading frame, which starts coding from the 3rd ATG relative to WT-CPE mRNA and encodes a 40kDa N-terminus truncated CPE protein. RT-PCR and Western blot analysis showed that 40kDa CPE-ΔN is expressed in multiple cancer cell lines and tumor tissues. Overexpression of this 40kDa CPE-ΔN variant up-regulated expression of multiple metastatic genes encompassing different signaling pathways, suggesting potentially an important role of CPE-ΔN in tumor metastasis.

Are the gut microbial systems of giant pandas unstable?

Animals have stable dominant gut microbiomes under similar diets. Similar diets can also lead to similar gut microbial communities within host species levels. Giant pandas (Ailuropoda melanoleuca) and red pandas (Ailurus fulgens) have had long-term and stable bamboo diets, and seem well adapted to this highly fibrous diet. When compared to the gut microbiomes of Père David's deer (Elaphurus davidianus), humans, cheetah (Acinonyx jubatus), black-backed jackal (Canis-mesomelas), and black bear (Ursus thibetanus), giant panda gut microbiomes have high variation in the abundance of Pseudomonadaceae and Clostridiaceae, and are somewhat unstable. This high instability and dissimilarity may reflect an unstable gut environment, perturbation or selective pressure because of their carnivorous gastrointestinal system. A short digestive tract, brief digestion time and fast intestinal peristalsis may result in higher oxygen concentrations that select for the growth of aerobes and facultative anaerobes in giant pandas. Potential selection of high proportion of Pseudomonadaceae in giant panda (GP-HP) and red panda gut microbiomes may arise because of their postulated ability to degrade secondary compounds (e.g., cyanide compounds and aromatic compounds). However, high proportion of Clostridiaceae (GP-HF) may focus on cellulose and hemicellulose digestion. Thus, GP-HP and GP-HF groups have high dissimilarity on the functional level. These findings show that long-term similarities in diet do not always lead to similar or stable gut microbial system within the same host species and that other factors can drive the selection of gut taxa.