Zehu Yuan

Previous studies have indicated that changes in LYPLA1 expression affect the proliferation and differentiation of fetal sheep myoblasts; however, the underlying molecular mechanisms remain unclear. This study examined transcriptional responses to LYPLA1 overexpression and knockdown in primary myoblasts derived from one Hu sheep fetus and explored the involvement of PI3K-Akt signaling in LYPLA1-associated proliferation. RNA sequencing showed that no differentially expressed genes remained significant after false discovery rate correction following LYPLA1 knockdown, whereas LYPLA1 overexpression yielded 362 significant genes, including 219 upregulated and 143 downregulated genes. Exploratory enrichment analysis of nominally significant candidate genes implicated extracellular and immune-related functions, steroid hormone biosynthesis, PPAR signaling, cytokine–cytokine receptor interaction, and PI3K-Akt signaling. Pharmacological inhibition with 0.5 μM PI3K/AKT-IN-1 partially attenuated the increases in EdU-positive cells and Cyclin D1 mRNA levels associated with LYPLA1 overexpression. These findings indicate that LYPLA1 overexpression is associated with broad transcriptional changes in ovine myoblasts and suggest that PI3K-Akt signaling contributes to the associated proliferative phenotype. However, the underlying mechanism requires further validation.

Lambing interval is an indicator of reproductive efficiency in ewes. This study characterized population-level lambing interval patterns in Hu and Tan sheep and evaluated three previously reported candidate SNPs in ADAMTSL1, CD226, and PAPPA. Among 256 genotyped Hu ewes and 94 genotyped Tan ewes, 244 and 92 ewes, respectively, had at least two valid lambing dates. After applying a unified quality-control range of 180–450 days, 711 intervals from 230 Hu ewes and 219 intervals from 82 Tan ewes were retained. The raw mean lambing intervals were 277.81 ± 27.56 days in Hu sheep and 368.81 ± 22.51 days in Tan sheep. After adjustment for parity, year, season, preceding litter size, and repeated ewe records, Tan sheep had an 80.99-day longer interval than Hu sheep (95% CI: 75.34–86.64 days; p = 3.17 × 10⁻¹²⁶). This difference remained significant across all parity groups. None of the three candidate SNPs was significantly associated with adjusted lambing interval after false-discovery-rate correction. Analyses of within-ewe interval variability also yielded no supported associations, although CD226 showed a weak, non-significant tendency toward lower variability in Hu sheep. These findings demonstrate a marked population-level difference in reproductive timing but do not support the immediate use of the tested SNPs as markers for lambing interval or within-ewe interval variability.

Multi-parity records improve ewe evaluation but require long-term follow-up. This study compared litter size, litter weight, and lambing type across four parities in 256 Hu sheep and 90 Tan sheep and evaluated six candidate SNPs in Hu sheep. The SNPs were confirmed by PCR and Sanger sequencing and genotyped using PARMS; repeated records were analyzed with mixed-effects models. The Hu sheep population showed higher litter weight and multiple-birth proportions than the Tan sheep population, together with a higher mean litter size. Analysis of 822 records from 256 Hu ewes showed that both traits increased from the first to the third parity and then remained stable; the same pattern occurred in 156 ewes with complete records. After BH-FDR correction, BMPR1B rs418841713 and TSHR rs406686139 were significantly associated with both traits. Association directions were unchanged when analyses were restricted to complete records, low-frequency genotypes were recoded, or lambing year was included. In an independent population, combined-genotype differences were nonsignificant, although GGCG had the numerically highest total litter size. An exploratory model indicated that first-parity litter size and both genotypes provided information on subsequent litter weight, but predictive performance was limited. These findings support further validation of BMPR1B and TSHR in Hu sheep.

Evidence from genome-wide association studies (GWAS) links genetic variants near the LYPLA1 locus to variations in sheep muscle development. To further investigate whether LYPLA1 expression plays a role in fetal sheep myoblast development, we performed gain-of-function/loss-of-function analyses targeting LYPLA1 using siRNA and recombinant vectors. CCK-8 assays, EdU staining, and flow cytometry were used to investigate the effects of both LYPLA1 knockdown and overexpression on the proliferation of fetal sheep myoblasts. Furthermore, this study investigated the effect of LYPLA1 on myogenic differentiation by means of indirect immunofluorescence staining with MyHC and quantitative analysis of myogenic regulatory factor (MRF) expression. The results showed that downregulation of LYPLA1 significantly reduced cell viability and proliferation rate, arrested myoblasts in the G2 phase, and inhibited proliferation. These effects were reversed when LYPLA1 was overexpressed. Furthermore, LYPLA1 knockdown significantly impaired myotube formation during terminal differentiation (days 5–7). This defect was correlated with a marked reduction in the expression of myogenic regulatory factors (MRFs). This effect was reversed when LYPLA1 was highly expressed. In summary, this study demonstrates that LYPLA1 promotes the proliferation and differentiation of fetal sheep myoblasts, establishing its potential as a target for the molecular breeding of sheep.

Compared to Chinese indigenous sheep, Western sheep have rapid growth rate, larger physique, and higher meat yield. These excellent Western sheep were introduced into China for crossbreeding to expedite the enhancement of production performance and mutton quality in local breeds. Here, we investigated population genetic structure and genome-wide selection signatures among the Chinese indigenous sheep and the introduced sheep based on whole-genome resequencing data. The PCA, N-J tree and ADMIXTURE results showed significant genetic difference between Chinese indigenous sheep and introduced sheep. The nucleotide diversity (π) and linkage disequilibrium (LD) decay results indicated that the genomic diversity of introduced breeds were lower. Then, F_st & π ratio, XP-EHH, and de-correlated composite of multiple signals (DCMS) methods were used to detect the selection signals. The results showed that we identified important candidate genes related to growth rate and body size in the introduced breeds. Selected genes with stronger selection signatures are associated with growth rate (CRADD), embryonic development (BVES, LIN28B, and WNT11), body size (HMGA2, MSRB3, and PTCH1), muscle development and fat metabolism (MSTN, PDE3A, LGALS12, GGPS1, and SAR1B), wool color (ASIP), and hair development (KRT71, KRT74, and IRF2BP2). Thus, these genes have the potential to serve as candidate genes for enhancing the growth traits of Chinese indigenous sheep. We also identified tail-length trait-related candidate genes (HOXB13, LIN28A, PAX3, and VEGFA) in Chinese long-tailed breeds. Among these genes, HOXB13 is the main candidate gene for sheep tail length phenotype. LIN28A, PAX3, and VEGFA are related to embryonic development and angiogenesis, so these genes may be candidate genes for sheep tail type traits. This study will serve as a foundation for further genetic improvement of Chinese indigenous sheep and as a reference for studies related to growth and development of sheep.

In order to investigate the effect of FecB on litter size and growth and development traits of Suhu meat sheep and the inheritance patterns of FecB between parents and offspring in the population. In this experiment, 2241 sheep from the Suhu meat sheep population were tested for FecB using capillary electrophoresis. We combined the lambing records of 473 ewes, the growth trait records of 881 sheep at both the birth and weaning (2-month-old) stages, and the complete genealogical records of 643 lambs to analysis the distribution of FecB in the Suhu meat sheep breeding population, its effect on litter size of ewes, growth and development of lambs, and the inheritance patterns of FecB. The results showed that there were three genotypes of FecB in the Suhu meat sheep population, namely the AA genotype, AG genotype, and GG genotype. FecB in this population has a moderate polymorphism (0.25 < PIC < 0.5), and deviates from Hardy–Weinberg disequilibrium (p < 0.05). The litter size of GG genotype ewes was significantly higher than that with the AG and AA genotypes (p < 0.01). A Chi-square test showed that the inheritance patterns of FecB follows Mendel’s Laws of Inheritance (p > 0.05). An association analysis of different genotypes of FecB with body weight and body size of Suhu meat sheep at birth and weaning revealed that FecB adversely affects the early growth and development of Suhu meat sheep. In summary, FecB can improve the litter size of ewes but it has negative effects on the early growth and survival rate of lambs in sheep. Therefore, FecB test results and feeding management measures should be comprehensively applied to improve the reproductive performance of ewes, the survival rate and production performance of lambs in sheep production, and thus improve the economic benefits of sheep farms.

Previous studies have demonstrated that CUX1 could contribute to the proliferation of DPCs in vitro, but the upstream transcriptional regulatory mechanisms of CUX1 remain largely unknown. This study aimed to investigate the upstream transcriptional regulators of CUX1 to enhance our comprehension of the mechanism of action of the CUX1 gene in ovine DPCs. Initially, the JASPAR (2024) software was used to predict the upstream target transcription factors for the CUX1 gene. Subsequently, through RT-qPCR and a double luciferase reporter assay, the interaction between SP1, KROX20, and CUX1 was established, respectively. The results indicated that SP1 and KROX20 were two highly reliable upstream transcription regulators for the CUX1 gene. Additionally, we found that SP1 promoted the proliferation of DPCs by overexpressing SP1 in DPCs, and KROX20 inhibited the proliferation of DPCs by overexpressing KROX20 in DPCs. These findings are also consistent with the transcriptional regulation of CUX1 by SP1 and KROX20, respectively. This study suggests that the effect of DPC proliferation in vitro by CUX1 may regulated by the transcription factors SP1 and KROX20.

This study aims to analyze the whole genome sequencing of E. coli F17 in antagonistic and susceptible Hu sheep lambs. The objective is to investigate the critical mutation loci in sheep and understand the genetic mechanism of sheep resistance to E. coli F17 at the genome level. Antagonist and susceptible venous blood samples were collected from Hu sheep lambs for whole genome sequencing and whole genome association analysis. A total of 466 genes with significant SNPs (p < 1.0 × 10⁻³) were found. GO and KEGG enrichment analysis and protein interaction network analysis were performed on these genes, and preliminary investigations showed that SNPs on CTNNB1, CDH8, APOD, HCLS1, Tet2, MTSS1 and YAP1 genes may be associated with the antagonism and susceptibility of Hu sheep lambs to E. coli F17. There are still some shortcomings that have not been explored via in vivo and in vitro functional experiments of the candidate genes, which will be our next research work. This study provides genetic loci and candidate genes for resistance of Hu sheep lambs to E. coli F17 infection, and provides a genetic basis for breeding disease-resistant sheep.

SRY-box transcription factor 18 (SOX18) is known to play a crucial role in the growth and development of hair follicles (HF) in both humans and mice. However, the specific effect of SOX18 on sheep hair follicles remains largely unknown. In our previous study, we observed that SOX18 was specifically expressed within dermal papilla cells (DPCs) in ovine hair follicles, leading us to investigate its potential role in the growth of hair follicles in sheep. In the present study, we aimed to examine the effect of SOX18 in DPCs and preliminarily study its regulatory mechanism through RNA-seq. We initially found that the overexpression of SOX18 promoted the proliferation of DPCs compared to the negative control group, while the interference of SOX18 had the opposite effect. To gain further insight into the regulatory mechanism of SOX18, we conducted RNA-seq analysis after knocking down SOX18 in Hu sheep DPCs. The result showed that the Wnt/β-Catenin signaling pathway was involved in the growth process of DPC after SOX18 knockdown. Subsequently, we investigated the effect of SOX18 on the Wnt/β-Catenin signaling pathway in DPCs using TOP/FOP-flash, qRT-PCR, and Western blot (WB) analysis. Our data demonstrated that SOX18 could activate the Wnt/β-Catenin signaling pathway in DPCs. Additionally, we observed that SOX18 could rescue the proliferation of DPCs after inhibiting the Wnt/β-Catenin signaling pathway. These findings underscore the essential role of SOX18 as a functional molecule governing the proliferation of DPCs. Additionally, these findings also greatly enhance our understanding of the role of SOX18 in the proliferation of DPCs and the growth of wool in Hu sheep.

Wool color is controlled by a variety of genes. Although the gene regulation of some wool colors has been studied in relative depth, there may still be unknown genetic variants and control genes for some colors or different breeds of wool that need to be identified and recognized by whole genome resequencing. Therefore, we used whole genome resequencing data to compare and analyze sheep populations of different breeds by population differentiation index and nucleotide diversity ratios (Fst and θπ ratio) as well as extended haplotype purity between populations (XP-EHH) to reveal selection signals related to wool coloration in sheep. Screening in the non-white wool color group (G1 vs. G2) yielded 365 candidate genes, among which PDE4B, GMDS, GATA1, RCOR1, MAPK4, SLC36A1, and PPP3CA were associated with the formation of non-white wool; an enrichment analysis of the candidate genes yielded 21 significant GO terms and 49 significant KEGG pathways (p < 0.05), among which 17 GO terms and 21 KEGG pathways were associated with the formation of non-white wool. Screening in the white wool color group (G2 vs. G1) yielded 214 candidate genes, including ABCD4, VSX2, ITCH, NNT, POLA1, IGF1R, HOXA10, and DAO, which were associated with the formation of white wool; an enrichment analysis of the candidate genes revealed 9 significant GO-enriched pathways and 19 significant KEGG pathways (p < 0.05), including 5 GO terms and 12 KEGG pathways associated with the formation of white wool. In addition to furthering our understanding of wool color genetics, this research is important for breeding purposes.