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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. [ABSTRACT FROM AUTHOR]

Simple Summary: Acute infectious diseases caused by Escherichia coli in lambs or young sheep have severe impacts on the growth and development of sheep, among which Escherichia coli F17 (Escherichia coli F17, E. coli F17) is one of the primary pathogens causing bacterial diarrhoea in lambs. The mechanism of lambs' resistance regulation to it remains to be elucidated. 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. [ABSTRACT FROM AUTHOR]

Copy number variation (CNV) is one kind of genomic structure variations and presents as gains and losses of genomic fragments. More recently, we have made an atlas of CNV maps for livestock. In the future, it is a primary focus to determine the phenotypic effects of candidate CNVs. Lysine Acetyltransferase 6 A (KAT6A) is a protein coding gene and plays a critical role in many cellular processes. However, the effects of KAT6A CNVs on sheep body measurements remains unknown. In this study, we performed quantitative polymerase chain reaction (qPCR) to detect the presences and distributions of three CNV regions within KAT6A gene in 672 sheep from four Chinese breeds. Association analysis indicated that the three CNVs of KAT6A gene were significantly associated with body measurement(s) in Small-tailed Han sheep (STH) and Hu sheep (HU) (p < 0.05), while no effects on Large-tailed Han sheep (LTH) were observed (p > 0.05) were observed. Additionally, only one CNV was significantly associated with body measurement (body length) in Chaka sheep (CK) (p < 0.05). Our study provided evidence that the CNV(s) of KAT6A gene could be used as candidate marker(s) for molecular breedings of STH, HU, and CK breeds. [ABSTRACT FROM AUTHOR]

Copy number variation (CNV) as an important source of genetic phenotypic and variation is related to complex phenotypic traits. The aim of this study was to investigate the potential associations of BAG4 (Bcl-2-associated athanogene 4) copy numbers variations with sheep growth traits in three Chinese sheep breeds (CKS, STHS, and HS). BAG4 is located within the stature and udder attachment quantitative trait loci (QTL) in sheep. Expression profiling revealed that the BAG4 gene was widely expressed in the tissues of sheep. The distribution of BAG4 gene copy number showed that the loss of copy number was more dominant in CKS and HS which was different from that in STHS. Statistical analysis revealed that the BAG4 CNV was significantly associated with body height in CKS (p < 0.05), with body slanting length in HS (p < 0.05), and with body height and hip cross height in STHS (p < 0.05). The χ2 values showed significant differences in the BAG4 CNV distribution frequency between varieties. In conclusion, the results establish the association between BAG4 CNV and sheep traits and suggest that BAG4 CNV may be a promising marker for the molecular breeding of Chinese sheep. [ABSTRACT FROM AUTHOR]

Copy number variations (CNVs) are important source of genetic variation, which can affect diverse economic traits through a variety of mechanisms. In addition, genome scan can identify many quantitative trait loci (QTLs) for the economic traits, while genome-wide association studies (GWAS) can localize genetic variants associated with the phenotypic variations. Here, we developed a method called GWAScore which collected GWAS summary data to identify potential candidates, and integrated CNVs into QTLs and high confidence GWAScore regions to detect crucial CNV markers for sheep growth traits. We got 197 candidate genes which were overlapping with the candidate CNVs. Some crucial genes (MYLK3 , TTC29 , HERC6 , ABCG2 , RUNX1 , etc.) showed significantly elevated GWAScore peaks than other candidate genes. In this study, we developed the GWAScore method to excavate the potential value of candidate genes as markers for the sheep molecular breeding. [ABSTRACT FROM AUTHOR]

Simple Summary: The meat production of Hu sheep affects the mutton supply, and how to increase the meat production is the primary focus of genetic breeding. Therefore, in order to explore the key factors affecting the proliferation and differentiation of Hu sheep skeletal muscle cells, we performed functional verification of miRNA at the cellular level. Our findings are helpful to clarify the molecular regulation mechanism of proliferation and differentiation of skeletal muscle cells, which will benefit the molecular breeding of Hu sheep. The growth and development of skeletal muscle require a series of regulatory factors. MiRNA is a non-coding RNA with a length of about 22 nt, which can inhibit the expression of mRNA and plays an important role in the growth and development of muscle cells. The role of miR-22-3p in C2C12 cells and porcine skeletal muscle has been reported, but it has not been verified in Hu sheep skeletal muscle. Through qPCR, CCK-8, EdU and cell cycle studies, we found that overexpression of miR-22-3p inhibited proliferation of skeletal muscle cells (p < 0.01). The results of qPCR and immunofluorescence showed that overexpression of miR-22-3p promoted differentiation of skeletal muscle cells (p < 0.01), while the results of inhibiting the expression of miR-22-3p were the opposite. These results suggested that miR-22-3p functions in growth and development of sheep skeletal muscle cells. Bioinformatic analysis with mirDIP, miRTargets, and RNAhybrid software suggested IGFBP3 was the target of miR-22-3p, which was confirmed by dual-luciferase reporter system assay. IGFBP3 is highly expressed in sheep skeletal muscle cells. Overexpression of IGFBP3 was found to promote proliferation of skeletal muscle cells indicated by qPCR, CCK-8, EdU, and cell cycle studies (p < 0.01). The results of qPCR and immunofluorescence experiments proved that overexpression of IGFBP3 inhibited differentiation of skeletal muscle cells (p < 0.01), while the results of interfering IGFBP3 with siRNA were the opposite. These results indicate that miR-22-3p is involved in proliferation and differentiation of skeletal muscle cells by targeting IGFBP3. [ABSTRACT FROM AUTHOR]

• KMT2D CNVs may have effects on sheep growth traits. • The median type of KMT2D CNV is a beneficial genotype to sheep breeds. • The KMT2D CNV could be used as a molecular marker for sheep breeding. Copy number variations (CNVs) are an important source of genetic variation, which can affect a wide range of economic traits by diverse mechanisms. KMT2D (Lysine methyltransferase 2D) is an important positional candidate for growth traits. Quantitative trait loci (QTLs) with large effects on economically important traits cover the KMT2D gene. The KMT2D gene overlays a CNV within its exons, hence it was chosen as a crucial candidate gene to study the association between CNV and growth traits. Further, KMT2D, a major mammalian histone H3K4 mono-methyltransferase, plays a critical role in regulating development, differentiation, metabolism, and tumor suppression. Therefore, we proposed the hypothesis that KMT2D CNV may have phenotypic effects on sheep growth traits. In our study, KMT2D CNVs in three Chinese sheep breeds were detected by quantitative polymerase chain reaction (qPCR), and the loss copy was found to be the dominant genotype. Association analysis between growth traits and KMT2D CNV was also performed, which revealed that individuals with the median copy showed better performance than those with the loss copy in all three breeds. This research suggested that KMT2D CNV can be used as a promising marker for sheep molecular breeding. [ABSTRACT FROM AUTHOR]