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Growth traits are quantitative traits controlled by multiple micro-effect genes. we identified molecular markers related to sheep growth traits, which formed the basis of molecular breeding. In this study, we randomly selected 100 Qira Black sheep and 84 German Merino sheep for the blood collection the jugular vein to genotype by using the Illumina Ovine SNP 50K Bead Chip. quality control criteria for statistical analysis were: rejection detection rate < 90% and minimum allele frequency (MAF) < 5%. Then, we performed Genome-wide association studies (GWAS) on sheep body weight, body height, body length, and chest circumference using mixed linear models. After getting 55 SNPs with significant correlation, they were annotated by reference genome of Ovis aries genome (Oar_v4.0) and We obtained a total of 84 candidate genes associated with production traits (BMPR1B, HSD17B3, TMEM63C, etc.). We selected BMPR1B for population validation and found a correlation between the FecB locus and body weight traits. Therefore, this study not only supplements the existing knowledge of molecular markers of sheep growth traits, but also has important theoretical significance and reference value for the mining of functional genes of sheep growth traits. [ABSTRACT FROM AUTHOR]

Lin28B plays an important role in puberty initiation in sheep. This study aimed to discuss the correlation between different growth periods and the methylation status of cytosine–guanine dinucleotide (CpG) islands in the promoter region of the Lin28B gene in the Dolang sheep's hypothalamus. In this study, the sequence of the Lin28B gene promoter region in Dolang sheep was obtained by cloning and sequencing, and methyl groups of the CpG island of the Lin28B gene promoter in the hypothalamus were detected by bisulfite sequencing PCR during the three periods of prepuberty, adolescence, and postpuberty in Dolang sheep. Lin28B expression in the Dolang sheep's hypothalamus was detected by fluorescence quantitative PCR at three stages: prepuberty, puberty, and postpuberty. In this experiment, the 2993-bp Lin28B promoter region was obtained, and it was predicted that there was a CpG island containing 15 transcription factor binding sites and 12 CpG sites, which may play a role in gene expression regulation. Overall, methylation levels increased from prepuberty to postpuberty, while Lin28B expression levels decreased, indicating that Lin28B expression was negatively correlated with promoter methylation levels. Variance analysis showed significant differences in the methylation status of CpG5, CpG7, and CpG9 between pre- and postpuberty (p < 0.05). Our data show that Lin28B expression is increased by demethylation of promoter CpG islands, with CpG5, CpG7, and CpG9 implicated as critical regulatory sites. [ABSTRACT FROM AUTHOR]

Simple Summary: Fecundity is an important economic trait of sheep that directly affects their economic and productive efficiency. Our study aimed to identify single nucleotide polymorphism (SNP) loci associated with sheep puberty or litter size which could be used in future breeding programs to improve fertility. We obtained one SNP on GNAQ gene (NC_040253.1: g.62677376G > A), which was associated with litter size in Cele Black sheep. Perhaps this SNP could be a criterion to screen polytocous sheep. Fecundity is an important economic trait in sheep that directly affects their economic and productive efficiency. Our study aimed to identify SNP loci associated with sheep puberty or litter size which could be used in future breeding programs to improve fertility. Genomic DNA was obtained from Hetian and Cele Black sheep breeds and used for reduced-representation genome sequencing to identify SNP loci associated with pubertal initiation and litter size. Selective signatures analysis was performed based on the fixation index and nucleotide diversity, followed by pathway analysis of the genes contained in the selected regions. The selected SNP loci in the genes associated with pubertal initiation and litter size were validated using both sheep breeds. In total, 384,718 high quality SNPs were obtained and 376 genes were selected. Functional annotation of genes and enrichment analysis identified 12 genes associated with pubertal initiation and 11 genes associated with litter size. SNP locus validation showed that two SNP on PAK1 and four on ADCY1 may be associated with pubertal initiation, and one SNP on GNAQ gene (NC_040253.1: g.62677376G > A) was associated with litter size in Cele Black sheep. Our results provide new theoretical support for sheep breeding. [ABSTRACT FROM AUTHOR]

Gonadotropin-releasing hormone (GnRH) is a key factor at the onset of puberty. This decapeptide has been found in mammalian ovaries, but its regulatory mechanism in the ovary of sheep at the onset of puberty is not clear. This study investigated the coding sequence (CDS) of the GnRH gene in the ovary of Duolang sheep and the expression of GnRH mRNA in different tissues at the onset of puberty, and analyzed the effect of GnRH on ovarian granulosa cells (GCs) of Duolang sheep. The results showed that the GnRH CDS of sheep was cloned, the full length of the GnRH CDS in sheep ovary was 279 bp, and the nucleotide sequence was completely homologous to that in the hypothalamus. The expression of GnRH mRNA was highest in the hypothalamus and ovary. The expression of related hormones and receptors in GCs of Duolang sheep treated with different concentrations of GnRH for 24 h was affected. GnRH significantly inhibited LH synthesis and LHR expression in GCs. Low concentration (100 ng mL -1) had the most obvious therapeutic effect on follicle-stimulating hormone (FSH) and FSHR. Higher concentration (250 ng mL -1) significantly promoted estradiol and ER β mRNA. These findings provide strong evidence that ovarian GnRH is an important regulatory factor at the onset of puberty in sheep. [ABSTRACT FROM AUTHOR]

Improving the fertility of sheep is an important goal in sheep breeding as it greatly increases the productivity. Dolang sheep is a typical representative breed of lamb in Xinjiang and is the main local sheep breed and meat source in the region. To explore the genes associated with the initiation of puberty in Dolang sheep, the hypothalamic tissues of Dolang sheep prepubertal, pubertal, and postpubertal periods were collected for RNA-seq analysis on the Illumina platform, generating 64.08 Gb clean reads. A total of 575, 166, and 648 differentially expressed genes (DEGs) were detected in prepuberty_vs._puberty, postpuberty_vs._prepuberty, and postpuberty_vs._puberty analyses, respectively. Based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, the related genes involved in the initiation of puberty in Dolang sheep were mined. Ten genes that have direct or indirect functions in the initiation of puberty in Dolang sheep were screened using the GO and KEGG results. Additionally, quantitative real-time PCR was used to verify the reliability of the RNA-Seq data. This study provided a new approach for revealing the mechanism of puberty initiation in sheep and provided a theoretical basis and candidate genes for the breeding of early-pubertal sheep by molecular techniques, and at the same time, it is also beneficial for the protection, development, and utilization of the fine genetic resources of Xinjiang local sheep. [ABSTRACT FROM AUTHOR]

Extreme environmental conditions are a major challenge for livestock production. Changes in climate conditions, especially those that lead to extreme weather, can reduce livestock production. The screening of genes and molecular markers is of great significance to explore the genetic mechanism of sheep prolificacy traits in Taklimakan Desert environment. We selected healthy adult Pishan Red Sheep (PRS) and Qira Black Sheep (QR) which live in Taklimakan Desert environment, collected blood from jugular vein, extracted DNA, and prepared Illumina Ovine SNP50 chip. For PRS, linkage disequilibrium (LD) was calculated using the ovine SNP50 Beadchip and the effective population size ( Ne ) was estimated using SMC++. The genetic characteristics of PRS were analyzed by integrated haplotype score (iHS) and fixation index ( F ST ). The result showed that r 2 of PRS was 0.233 ± 0.280 in the range of 0-10 Kb and decreased with increasing distances. SMC++ tested that the Ne of PRS remained at 236.99 in recent generations. 184 genes were screened out under iHS 1% threshold, and 1148 genes were screened out with F ST under the 5% threshold, and 29 genes were obtained from the intersection of the two gene sets. In this study, the genetic characteristics of PRS and QR were compared by ovine genome chip, and the related excellent genes were searched, providing reference for the protection of sheep germplasm resources and molecular breeding in a desert environment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Zhang, Zhang, Tuersuntuoheti, Chang and Liu.)

Fecundity is an important economic trait in sheep that directly affects their economic and productive efficiency. Our study aimed to identify SNP loci associated with sheep puberty or litter size which could be used in future breeding programs to improve fertility. Genomic DNA was obtained from Hetian and Cele Black sheep breeds and used for reduced-representation genome sequencing to identify SNP loci associated with pubertal initiation and litter size. Selective signatures analysis was performed based on the fixation index and nucleotide diversity, followed by pathway analysis of the genes contained in the selected regions. The selected SNP loci in the genes associated with pubertal initiation and litter size were validated using both sheep breeds. In total, 384,718 high quality SNPs were obtained and 376 genes were selected. Functional annotation of genes and enrichment analysis identified 12 genes associated with pubertal initiation and 11 genes associated with litter size. SNP locus validation showed that two SNP on PAK1 and four on ADCY1 may be associated with pubertal initiation, and one SNP on GNAQ gene (NC&#95;040253.1: g.62677376G > A) was associated with litter size in Cele Black sheep. Our results provide new theoretical support for sheep breeding.