Background: The mechanism of body growth in mammals is poorly understood. Here, we investigated the regulatory networks involved in body growth through transcriptomic analysis of pituitary and epiphyseal tissues of smaller sized Debao ponies and Mongolian horses at the juvenile and adult stages. Results: We found that growth hormone receptor (GHR) was expressed at low levels in long bones, although growth hormone (GH) was highly expressed in Debao ponies compared with Mongolian horses. Moreover, significant downregulated of the GHR pathway components m-RAS and ATF3 was found in juvenile ponies, which slowed the proliferation of bone osteocytes. However, WNT2 and PLCβ2 were obviously upregulated in juvenile Debao ponies, which led to premature mineralization of the bone extracellular matrix. Furthermore, we found that the WNT/Ca²⁺ pathway may be responsible for regulating body growth. GHR was demonstrated by q-PCR and Western blot analyses to be expressed at low levels in long bones of Debao ponies. Treatment with WNT antagonistI decreased the expression of WNT pathway components (P < 0.05) in vitro. Transduction of ATDC5 cells with a GHR-RNAi lentiviral vector decreased the expression of the GHR pathway components (P < 0.05). Additionally, the expression of the IGF-1 gene in the liver was lower in Debao ponies than in Mongolian horses at the juvenile and adult stages. Detection of plasma hormone concentrations showed that Debao ponies expressed higher levels of IGF-1 as juveniles and higher levels of GH as adults than Mongolian horses, indicating that the hormone regulation in Debao ponies differs from that in Mongolian horses. Conclusion: Our work provides insights into the genetic regulation of short stature growth in mammals and can provide useful information for the development of therapeutic strategies for small size.

Background: Mongolian cattle (MC) is one of an ancient livestock breeds with good economic traits such as adaptation to Mongolian Plateau extreme low temperature in winter, resistant to pathogenic organisms infection and high quality meat. To reveal the molecular mechanism underlying these, the whole genome sequencing and comparative transcriptome sequencing of MC were performed.Results：By genome sequencing and structure variation analysis, 8 genes related to pathogenic organisms infection, including 4 members of bata-defensins gene family (LAP, DEFB1, DEFB2, and DEFB5), 2 members of interferon (IFN) gene family (IFNW1 and IFNT2) and 2 genes coding for BoLA proteins(Mongolian_cattle_21532 and Mongolian_cattle_19448) were found in MC genome inversion region. By transcriptome-sequencing, it was elucidated that 8 genes (FATP, FABP, PEPCK, SCP-X, ADIPO, FABP1, SCD-1, APO) related to PPARα pathway, 23 genes involved in oxidative phosphorylation and 10 P450 genes (CYP7B1, CYP4V2, CYP3A5, CYP11A1, CYP2C18, CYP2B6, CYP7A1, CYP2R1, CYP2E1, CYP27B1) were significantly up-regulated in winter MC transcriptomes, comparative to summer MC transcriptomes.Conclusions: Here, we characterized 41 genes implicated in fatty acid metabolism were up-regulated in winter MC transcriptomes. These genes probably account for the MC adaptation to extreme low temperature. At the same time, 8 genes in MC genome inversion region were discovered. And these genes gave clue to the MC resistant to pathogenic organisms infection. In sum, our revealed genes are of important for us to understand the molecular mechanisms of MC to adapt to their environments and valuable for cattle breeding.

This study aims to establish an immortalized fibroblast cell line from Mongolian sheep. Primary Mongolian sheep fibroblasts (SSF) were isolated using tissue explant and enzymatic digestion methods, followed by microscopic observation, growth curve plotting, and karyotype analysis. The results confirmed the successful isolation of SSF. Human (hTERT) and sheep (sTERT) telomerase reverse transcriptase vectors were separately introduced into SSF, with cells passaged up to 36 generations following G418 selection. Microscopic examination and qRT-PCR results demonstrated that TERT transfection did not alter the morphology of SSF and led to stable, high levels of TERT expression (P < 0.01). Cell counting and flow cytometry revealed that TERT-transfected cells had higher viability and lower apoptosis rates compared to SSF (P < 0.05). Karyotype and soft agar colony formation assays indicated that hTERT and sTERT-transfected cells maintained normal characteristics without malignant transformation. β-galactosidase staining indicated that TERT transfection significantly reduced cellular senescence (P < 0.001). Additionally, sTERT-transfected cells exhibited higher TERT expression, enhanced viability, proliferation, and anti-senescence effects compared to hTERT-transfected cells (P < 0.05). In summary, the introduction of hTERT and sTERT effectively extends the lifespan of SSF, with sTERT demonstrating a more pronounced effect. This study provides critical evidence for preserving Mongolian sheep genetic resources and developing immortalized cell lines.

Introduction: The longissimus dorsi muscle of Bactrian camels holds significant biological and economic value. However, the cellular heterogeneity, lineage differentiation patterns, and intercellular communication mechanisms underlying its skeletal muscle development remain unclear, which has hampered the advancement of precise regulation of camel meat quality traits and genetic improvement of the breed. Accordingly, there is an urgent need to elucidate the developmental regulatory mechanisms of this muscle tissue at the single-cell level. Methods: In this study, longissimus dorsi muscle tissues from 4-day-old (juvenile) and 5-year-old (adult) Bactrian camels were selected as research subjects. Integrated single-nucleus RNA sequencing (snRNA-seq) was employed to obtain gene expression data, which was coupled with Monocle2 pseudotime analysis, CellChat-based intercellular communication dissection, Gene Ontology (GO) enrichment analysis, and C2C12 cell functional validation experiments to conduct a systematic investigation into the cellular characteristics and developmental mechanisms of the Bactrian camel longissimus dorsi muscle. Results: A total of 14 cell clusters were identified, and the cellular composition of muscle tissues differed significantly between age groups—juvenile camel muscles were enriched with proliferative cell populations such as muscle satellite cells (MuSCs) and fibroblast-like progenitor cells (FAPs), while adult camel muscles were dominated by mature type IIX/IIA fast-twitch muscle fibers. Further analysis revealed that MuSCs exhibited bidirectional differentiation potential towards type I slow-twitch muscle fibers and type IIA/IIX fast-twitch muscle fibers, and the PCDH7 gene was found to promote myogenic differentiation. Additionally, four FAP subpopulations were characterized, among which the MME ⁺ FAP subpopulation was closely associated with intramyocellular fat (IMF) deposition. Discussion: This study, for the first time, constructed a single-cell atlas and intercellular communication network of the Bactrian camel longissimus dorsi muscle, uncovered the key regulatory mechanisms governing its skeletal muscle development, and identified functionally important regulatory targets such as PCDH7. These findings not only provide a theoretical basis for the precise improvement of camel meat quality but also laid the groundwork for in-depth investigations into the adaptive evolutionary mechanisms of camel skeletal muscle.