Intestinal acetic acid regulates the synthesis of sex pheromones in captive giant pandas.

As a typical solitary animal, adult giant pandas rely on chemical signals (sex pheromones) to transmit reproductive information during oestrous. Although researchers have confirmed that the gut microbiota is related to the emission and reception of sex pheromones, there is no clear correlation between the gut microbes and the synthesis of sex pheromone of giant pandas, that is, which gut microbes and microbial metabolites are participate in the synthesis of giant panda's sex pheromone. As a mirror of gut microbiota, fecal microbiota can reflect the composition of gut microbiota and its interaction with host to some extent. The purpose of this study is to explore how the gut microbes affect the synthesis of sex pheromones in captive giant pandas by combining analysis of the fecal microbiome and metabolomics. The results of correlation and microbial function analysis show that intestinal microorganisms such as Veillonellaceae and Lactobacillilaceae are associated with the synthesis of short chain fatty acid (acetic acid) and volatile ester metabolites, such as 1-butanol, 3-methyl, acetate, acetic acid, hexyl ester and 3-hexen-1-ol, acetate, (Z). In summary, based on this study, we believe that volatile metabolites such as fecal acetate participate in the process of mate preference of captive giant pandas and affect their expression of natural mating behavior. The possible mechanism is that the gut microbes can promote the synthesis of key chemical signaling substances in perianal glands through mediated intermediate fecal metabolites, thus affecting the normal information exchange between giant pandas individuals. The results of this study have greatly enriched our understanding of gut microbes regulating the synthesis of sex pheromones in giant pandas.

Characteristics of mesenchymal stem cells and their exosomes derived from giant panda (Ailuropoda melanoleuca) endometrium.

Conservation of genetic resources is an important way to protect endangered species. At present, mesenchymal stem cells (MSCs) have been isolated from the bone marrow and umbilical cords of giant pandas. However, the types and quantities of preserved cell resources were rare and limited, and none of MSCs was derived from female reproductive organs. Here, we first isolated MSCs from the endometrium of giant panda. These cells showed fibroblast morphology and expressed Sox2, Klf4, Thy1, CD73, CD105, CD44, CD49f, and CD105. Endometrium mesenchymal stem cells (eMSCs) of giant panda could induce differentiation into three germ layers in vitro. RNA-seq analysis showed that 833 genes were upregulated and 716 genes were downregulated in eMSCs compared with skin fibroblast cells. The results of GO and the KEGG analysis of differentially expressed genes (DEGs) were mainly focused on transporter activity, signal transducer activity, pathways regulating pluripotency of stem cells, MAPK signaling pathway, and PI3K-Akt signaling pathway. The genes PLCG2, FRK, JAK3, LYN, PIK3CB, JAK2, CBLB, and MET were identified as hub genes by PPI network analysis. In addition, the exosomes of eMSCs were also isolated and identified. The average diameter of exosomes was 74.26 ± 13.75 nm and highly expressed TSG101 and CD9 but did not express CALNEXIN. A total of 277 miRNAs were detected in the exosomes; the highest expression of miRNA was the has-miR-21-5p. A total of 14461 target genes of the whole miRNAs were predicted and proceeded with functional analysis. In conclusion, we successfully isolated and characterized the giant panda eMSCs and their exosomes, and analyzed their functions through bioinformatics techniques. It not only enriched the conservation types of giant panda cell resources and promoted the protection of genetic diversity, but also laid a foundation for the application of eMSCs and exosomes in the disease treatment of giant pandas.

Comparison of transcriptome profiles of mesenchymal stem cells derived from umbilical cord and bone marrow of giant panda (Ailuropoda melanoleuca).

Mesenchymal stem cells (MSCs) have pluripotent differentiation ability and play an important role in human clinical cell therapy. While, the research on MSCs in endangered wild animals is extremely rare. In our previous studies, the bone marrow mesenchymal stem cells (bmMSCs) and umbilical cord mesenchymal stem cells (ucMSCs) of giant panda (Ailuropoda melanoleuca) were successfully isolated. We aimed to characterize the differences in gene expression profiles between these two types of MSCs using RNA sequencing (RNA-Seq) and to determine which potential pathways are involved in functional regulation. In total, 1079 significantly differentially expressed genes (DEGs) were identified, of which 478 genes were upregulated and 601 genes were downregulated. The significantly enriched Gene Ontology (GO) terms mainly contained cell adhesion, biological adhesion, intracellular signal transduction, molecular function regulator, Ras protein signal transduction, small GTPase mediated signal transduction, and regulation of Rho protein signal transduction. The most enrichment pathways of DEGs enriched in Kyoto Encyclopedia of Genes Genomes (KEGG) were PI3K-AKT signaling pathway, Rap1 signaling pathway, MAPK signaling pathway, Hippo signaling pathway, Wnt signaling pathway, cGMP-PKG signaling pathway and Signaling pathways regulating pluripotency of stem cells. In addition, quantitative real time polymerase chain reaction (qRT-PCR) showed that the AKT3, CDK2, MAPK3, mTOR, PI3K and PTK2 genes associated with PI3K-AKT pathway were highly expressed (P < 0.01), and Caspase-3 was low expressed (P < 0.05) in ucMSCs group when compared with bmMSCs. After treatment with the PI3K inhibitor LY294002, genes AKT3, CDK2, MAPK3, mTOR, and PTK2 were significantly decreased in ucMSCs (P < 0.01), and Caspase-3 was significantly up regulated (P < 0.001). In conclusion, we for the first time compared and analyzed the transcriptome profiles of giant panda ucMSCs and bmMSCs, and found the PI3K-AKT pathway was highly activated and might be a key signaling pathway in the ucMSCs regulation. This study will be beneficial for the research on MSCs proliferation regulation and differentiation of giant pandas in the future, and lay the foundation for MSCs application and clinical therapy for endangered wild animals.

Combined urine metabolomics and 16S rDNA sequencing analyses reveals physiological mechanism underlying decline in natural mating behavior of captive giant pandas.

The decline in natural mating behavior is the primary reason underlying in the poor population growth of captive giant pandas. However, the influencing factors and underlying mechanisms remain unclear to data. It is speculated that the decline in natural mating behavior could be related to the psychological stress caused by captivity, which restricts their free choice of mates. In order to test this hypothesis, we performed urinary metabolomics analysis using Ultra-High-Performance Liquid Chromatography-Mass Spectrometry (UHPLC/-MS) combined with 16S rDNA sequencing for exploring the physiological mechanism underlying the decline in the natural mating behavior of captive giant panda. The results demonstrated that the decline in mating ability could be related to abnormalities in arginine biosynthesis and neurotransmitter synthesis. Additionally, the relative abundance of bacteria from the Firmicutes, Proteobacteria, and Actinobacteria phyla and the Acinetobacter, Weissella, and Pseudomonas genus was significantly reduced in the group with low natural mating behavior. These findings imply that the inhibition of arginine synthesis induced by environmental changes could be related to the poor libido and failure of mate selection in captive giant pandas during the breeding period. The results also demonstrate the relationship between the altered urinary microbes and metabolites related to arginine and neurotransmitter synthesis. These findings may aid in understanding the mechanism underlying environment-induced mate selection in captive giant pandas and propose a novel strategy for determining the sexual desire of giant pandas based on urinary microbes. The method would be of great significance in improving the natural reproductive success rate of captive giant pandas.

Isolation and characterization mesenchymal stem cells from red panda (Ailurus fulgens styani) endometrium.

Endometrial mesenchymal stem cells (eMSCs) are undifferentiated endometrial cells with self-renewal, multidirectional differentiation and high proliferation potential. Nowadays, eMSCs have been found in a few species, but it has never been reported in endangered wild animals, especially the red panda. In this study, we successfully isolated and characterized the eMSCs derived from red panda. Red panda eMSCs were fibroblast-like, had a strong proliferative potential and a stable chromosome number. Pluripotency genes including Klf4, Sox2 and Thy1 were highly expressed in eMSCs. Besides, cultured eMSCs were positive for MSC markers CD44, CD49f and CD105 and negative for endothelial cell marker CD31 and haematopoietic cell marker CD34. Moreover, no reference RNA-seq was used to analyse the eMSCs transcriptional expression profile and key pathways. Compared with skin fibroblast cell group, 9104 differentially expressed genes (DEGs) were identified, among which are 5034 genes upregulated, 4070 genes downregulated and the top 20 enrichment pathways of DEGs in Gene Ontology (GO) and the Kyoto Encyclopedia of Genes Genomes (KEGG) mainly associated with G-protein coupled receptor signalling pathway, carbohydrate derivative binding, nucleoside binding, ribosome biogenesis, cell cycle, DNA replication, Ras signalling pathway and purine metabolism. Among the DEGs, some representative genes about promoting MSCs differentiation and proliferation were upregulated and promoting fibroblasts proliferation were downregulated in eMSCs group. Red panda eMSCs also had multiple differentiation ability and could differentiate into adipocytes, chondrocytes and hepatocytes. In conclusion, we, for the first time, isolated and characterized the red panda eMSCs with ability of multiplication and multilineage differentiation in vitro. The new multipotential stem cell could be beneficial not only for the germ plasm resources conservation of red panda, but also for basic or pre-clinical studies in the future.

Characteristics of Mesenchymal Stem Cells Isolated from the Bone Marrow of Red Pandas.

Mesenchymal stem cells (MSC) have strong therapeutic potential due to their capacity for self-renewal and multilineage differentiation. MSCs can also be useful in preserving the current genetic diversity of endangered wildlife. To date, MSCs from various species have been studied, but only a few species of endangered wild animals have been reported. Adult bone marrow (BM) is a rich source of mesenchymal stem cells. The aim of this study was to isolate and characterize MSCs derived from the BM of red pandas. Red panda BM-MSCs isolated from five individuals were fibroblast-like cells, similar to other species. Cultured BM-MSCs with normal karyotype were negative for the hematopoietic line marker CD34 and the endothelial cell marker CD31 but were positive for MSC markers, including CD44, CD105 and CD90. RT-PCR and western blot analysis showed self-renewal and pluripotency genes, including Oct4, Sox2 and Klf4, were also expressed in red panda BM-MSCs. Finally, red panda BM-MSCs had the potential for differentiation into osteogenic, adipogenic and neuron-like cells by using a combination of previously reported protocols for other species. We have therefore demonstrated that cells harvested from red panda bone marrow are capable of extensive in vitro multiplication and multilineage differentiation, which is an essential step toward their use in the preservation of red pandas biological diversity and future studies on MSC applications in endangered species.

Effects of extender type on the quality of post-thaw giant panda (Ailuropoda melanoleuca) semen.

Sperm cryopreservation is an essential approach for assisted reproduction and genetic resources conservation in captive giant pandas. Cryopreservation, however, leads to a significant decrease in sperm quality and, consequently, a low fertilization rate. Therefore, it is mandatory to disclose more suitable and efficient freezing strategies for sperm cryopreservation. In the present study, we compared for the first time the performance of two commercial freeze extender (INRA96 versus TEST) freezing methods on post-thawed semen quality. Semen cryopreserved with the INRA96 showed better total motility (73.00 ± 4.84% vs 57.56 ± 3.60%, P < 0.001), membrane integrity (60.92 ± 2.27% vs 40.53 ± 2.97%, P < 0.001) and acrosome integrity (90.39 ± 2.74% vs 84.26 ± 4.27%, P < 0.05) than stored with TEST. There was no significant difference in DNA integrity after thawing between the two extenders (95.69 ± 3.60% vs 94.26 ± 4.84%). In conclusion, the INRA96 method showed to be better for giant panda sperm cryopreservation and should therefore be recommended for use in order to increase success of artificial insemination.

The cryoprotective effect of low-density lipoproteins in extenders on bull spermatozoa following freezing-thawing.

Egg low-density lipoprotein (LDL) was added at concentrations of 7-10% to the extenders used to freeze bull semen and its effects on the motility, mitochondria activity, acrosome integrity, membrane integrity and DNA integrity of frozen-thawed sperm were assessed. Analysis of data showed that the motility and characteristics of spermatozoa movement were higher with LDL in the extender, as compared to the extender containing 20% egg yolk. The results indicated that 8% LDL supplementation provided the highest sperm motility (55.8%) and movement characteristics (VSL, straight linear velocity: 33.8 microm/s; VCL, curvilinear velocity: 50.2 microm/s; LIN, linearity index: 56.5%; STR, mean coefficient: 76.7%; VAP, average path velocity: 35.9 microm/s; WOB, wobble coefficient: 63.9%). A concentration of 10% LDL resulted in a significant decline in the VSL, LIN, VAP and WOB values (P<0.05). Supplementation of LDL at 8% LDL resulted in significantly higher spermatozoa mitochondrial activity, acrosome integrity, membrane integrity and DNA integrity (P<0.05). According to all measured parameters, the extender containing 8% LDL showed beneficial cryoprotective effects on frozen-thawed bull spermatozoa. In conclusion, our results indicated that the extender containing 8% LDL extracted from egg yolk could be used successfully in the cryopreservation of bull semen with an efficacy that would be greater than present extenders containing 20% egg yolk.

[Overexpression of the truncated fosb isoform (Delta2Deltafosb) increases nodus in CD1 primary osteoblastes].

The recombinant adenoviruses which can overexpress fosb and Delta2Deltafosb proteins were produced. Primary calvarial osteoblasts from new born CD1 mice were infected with those adenoviruses by different proportion of Ad-Delta2Deltafosb and induced by 5 mmol/L beta-glycerophosphate, 50 microg/ml ascorbic acid and 10 nmol/L dexamethasone for 23 days and 29 days, respectively. The results by Alizarin Red Staining showed that the primary osteoblasts overexpressing Delta2Deltafosb protein formed more nodus than the control cells and the nodus in overexpressing Delta2Deltafosb protein osteoblasts were smaller than those in control cells on day 23. Differentiation of the primary osteoblasts overexpressing Delta2Deltafosb protein increased more than that of the control cells on day 29. It is an evidence for the reason that bone density of Delta2Deltafosb transgenic mice was markedly increased throughout the skeleton in new born and mature mice.