Genome-wide selection signal analysis reveals the adaptability of Tibetan sheep to high altitudes.

Altitude adaptation is a complex process involving multiple physiological and biochemical responses to hypoxia and other environmental stresses. In-depth genetic analysis of Tibetan sheep, which exhibit significant adaptations to high-altitude hypoxia, promises to elucidate hypoxia-tolerance mechanisms in plateau animals. Here, we conducted a genome-wide selection scan on three Tibetan sheep populations: low-altitude Tao (TS; 2887 m), medium-altitude Tianjun white (WT; 3331 m), and high-altitude Huoerba (HB; 4614 m).

The mechanism of m6A methylation analysis of the transcriptome to regulate the diameter of Alpine Merino wool fiber.

Objective: Wool is an important textile raw material, and fiber diameter is a major determinant of the economic value and quality of wool products. Analyses of the regulatory mechanisms underlying wool fiber diameter are necessary for the development of strategies to improve wool fineness. Therefore, we used methylationomics to analyze the skin tissue of individuals with different fiber diameters, and analyzed the apparent regulation mechanism of wool fiber diameter.

Defining Multi-Trait Breeding Objectives and Selection Indexes to Develop More Efficient Breeding Programs for Superfine Wool Sheep.

This study aimed to develop an optimized breeding program for the Alpine Merino sheep superfine strain by defining breeding objectives and establishing a multi-trait selection index. Using phenotypic and genetic (co)variance components of wool and growth traits, we identified six key breeding objectives: average fiber diameter (AFD), clean fleece weight (CFW), staple strength (SS), staple length (YSL), yearling weight (YWT), and weaning weight (WWT), with economic weights of 48, 48.5, 2, 12, 2.

Multi-omics insights into key microorganisms and metabolites in Tibetan sheep's high-altitude adaptation.

Tibetan sheep gastrointestinal microbial communities and metabolites showed adaptive differences with altitude, but we do not know which flora or metabolites may play an important role in acclimatization to the altitude environment. Therefore, we systematically analyzed the microbial structure and metabolites in the rumen and feces of Tibetan sheep at two altitudes (4,424 m and 2,364 m) using amplicon sequencing and untargeted metabolomics. The results showed that the bacterial communities differed greatly between the two groups, with high altitude Tibetan sheep having a higher forage fermentation capacity, and the abundance of some bacteria and fungi that were conducive to the decomposition of cellulose in rumen fluid increased significantly (especially Bacteroidota, Neocallimastigomycota, and Ascomycota), and the short chain fatty acids and NH-N produced by metabolism also increased.

Transcriptome-Metabolome Analysis Reveals That Crossbreeding Improves Meat Quality in Hu Sheep and Their F-Generation Sheep.

Consumers are increasingly demanding higher-quality mutton. Crossbreeding has been recognized as an effective means to improve meat quality. However, the phenomenon underlying these molecular system mechanisms remains largely unidentified.

Identification and profiling of microRNAs during sheep's testicular development.

The normal development of the testis is essential for male reproduction, as it is the site of sperm production and a prerequisite for spermatogenesis. MiRNAs play crucial roles in various testicular biological processes, including cell proliferation, spermatogenesis, hormone secretion, metabolism, and reproductive regulation. In this study, we utilized deep sequencing data to analyze the expression patterns of small RNAs in testicular tissues of Southern × Hu sheep F1 hybrids at 0, 3, 6 months, and 1 year of age, thereby exploring the functions of miRNAs in testicular development and spermatogenesis.

and Regulate Heat Stress Response in Hu Sheep Through Lipid Metabolism via m6A Modification.

In an established hepatocyte lipid deposition heat stress model, the expression levels of and were significantly upregulated ( < 0.05), indicating that and play important roles in the process of lipid deposition heat stress in hepatocytes. Transcriptome and metabolome analyses showed that lipid deposition heat stress had significant effects on the linoleic acid, linolenic acid, glycerophospholipid, and arachidonic acid metabolic pathways in hepatocytes.

Comprehensive analysis of the transcriptome-wide m6A Methylome in sheep testicular development.

N6-methyladenosine (m6A) modification of RNA is a critical post-transcriptional modification, that dynamically contributes to testicular development and spermatogenesis. Nevertheless, the investigation into the role of m6A in testicular development of sheep remains insufficient. Herein, we conducted a comprehensive analysis of the m6A transcriptome landscape in the testes of F1 hybrid Southdown × Hu sheep across M0 (0 months old, newborn), M3 (3 months old, sexually immature), M6 (6 months old, sexually mature), and Y1 (1 years old, adult).

The accumulation of harmful genes within the ROH hotspot regions of the Tibetan sheep genome does not lead to genetic load.

Background: Prolonged natural selection and artificial breeding have contributed to increased uniformity within the Tibetan sheep population, resulting in a reduction in genetic diversity and the establishment of selective signatures in the genome. This process has led to a loss of heterozygosity in specific genomic regions and the formation of Runs of Homozygosity (ROH). Current research on ROH predominantly focuses on inbreeding and the signals of selection; however, there is a paucity of investigation into the genetic load and selective pressures associated with ROH, both within these regions and beyond.

FGF20 Secreted From Dermal Papilla Cells Regulate the Proliferation and Differentiation of Hair Follicle Stem Cells in Fine-Wool Sheep.

Wool traits determine the market value of fine-wool sheep, and wool fibre-breaking elongation (fibres can be stretched or elongated before they break) is one of the important wool traits. The interaction between hair follicle stem cells (HFSCs) and dermal papilla cells (DPCs) determines hair follicle development in fine wool sheep, thereby directly influencing wool traits. A genome-wide association study based on pre-sequencing data identified FGF20, which was significantly associated with wool fibre-breaking elongation.

Transcriptome and metabolome revealed the effects of hypoxic environment on ovarian development of Tibetan sheep.

Many studies on the adaptability of Tibetan sheep to hypoxia have been reported, but little attention has been paid to the reproduction of Tibetan sheep living at an altitude of more than 4000 m. In this study, the ovaries of Alpine Merino sheep (AM) living in middle-high altitude areas (2500 m) and the ovaries of Gangba Tibetan sheep (GB) and Huoba Tibetan sheep (HB) living in ultra-high altitude areas (4400 m or more) were collected. Through morphological, transcriptomics and metabolomics, the effects of ultra-high altitude areas on Tibetan sheep ovarian development and the molecular mechanism of sheep's adaptability to ultra-high altitude environment were explored.

Transcriptomic Study of Different Stages of Development in the Testis of Sheep.

Numerous genes govern male reproduction, modulating testicular development and spermatogenesis. Our study leveraged RNA-Seq to explore candidate genes and pivotal pathways influencing fecundity in an F1 hybrid of Southdown × Hu sheep testes across four developmental milestones: M0 (0 months old, newborn), M3 (3 months old, sexually immature), M6 (6 months old, sexually mature), and Y1 (1 years old, adult). Histological examination using hematoxylins and eosin staining revealed that the cross-sectional area of the spermatid tubules and the number of supportive cells increased in the other groups, as compared to the M0 group.

Integration analysis of transcriptome and metabolome revealed the potential mechanism of spermatogenesis in Tibetan sheep (Ovis aries) at extreme high altitude.

Testis has an indispensable function in male reproduction of domestic animals. Numerous genes and metabolites were related to testicular development and spermatogenesis. However, little is known about the biological regulation pathways associated with fecundity in male Tibetan sheep.

Hybridization promotes growth performance by altering rumen microbiota and metabolites in sheep.

Hybridization can substantially improve growth performance. This study used metagenomics and metabolome sequencing to examine whether the rumen microbiota and its metabolites contributed to this phenomenon. We selected 48 approximately 3 month-old male ♂Hu × ♀Hu (HH,  = 16), ♂Poll Dorset × ♀Hu (DH,  = 16), and ♂Southdown × ♀Hu (SH,  = 16) lambs having similar body weight.

Resequencing reveals population structure and genetic diversity in Tibetan sheep.

Background: The Tibetan sheep is one of the three major primitive sheep breeds in China, representing a unique and high-quality genetic resource in the Qinghai-Tibet Plateau and neighboring high-altitude regions, exhibiting exceptional adaptability to high-altitude climatic environments. However, research on the genetic relationships among different populations of Tibetan sheep at the whole-genome level remains insufficient. This study aims to explore the population structure and historical dynamics among 11 Tibetan sheep populations, accurately assess the genetic diversity within the populations, and providing a theoretical basis for the development of targeted genetic breeding strategies for Tibetan sheep.

The molecular regulated mechanism of METTL3 and FTO in lipid metabolism of Hu sheep.

Background: Balanced lipid metabolism can improve the growth performance and meat quality of livestock. The m6A methylation-related genes METTL3 and FTO play important roles in animal lipid metabolism; however, the mechanism through which they regulate lipid metabolism in sheep is unclear.

Results: We established lipid deposition models of hepatocytes and preadipocytes in Hu sheep.

Inhibitor of Myom3 inhibits proliferation and promotes differentiation of sheep myoblasts.

Skeletal muscle quality and yield are important production traits in livestock, and improving skeletal muscle quality while increasing its yield is an important goal of economic breeding. The proliferation and differentiation process of sheep myoblasts directly affects the growth and development of their muscles, thereby affecting the yield of mutton. Myomesin 3 (Myom3), as a functional gene related to muscle growth, currently lacks research on its function in myoblasts.

Delta-like noncanonical notch ligand 2 regulates the proliferation and differentiation of sheep myoblasts through the Wnt/β-catenin signaling pathway.

This study delved into the role of delta-like noncanonical notch ligand 2 (DLK2) in the cell cycle, proliferation, apoptosis, and differentiation of myoblasts, as well as its interaction with the classical Wnt/β-catenin signaling pathway in regulating myoblast function. The research revealed that upregulation of DLK2 in myoblasts during the proliferation phase enhanced myoblast proliferation, facilitated cell cycle progression, and reduced apoptosis. Conversely, downregulation of DLK2 expression using siRNA during the differentiation phase promoted myoblast hypertrophy and fusion, suppressed the expression of muscle fiber degradation factors, and expedited the differentiation process.

Genomic Selection for Weaning Weight in Alpine Merino Sheep Based on GWAS Prior Marker Information.

This study aims to compare the accuracy of genomic estimated breeding values (GEBV) estimated using a genomic best linear unbiased prediction (GBLUP) method and GEBV estimates incorporating prior marker information from a genome-wide association study (GWAS) for the weaning weight trait in highland Merino sheep. The objective is to provide theoretical and technical support for improving the accuracy of genomic selection. The study used a population of 1007 highland Merino ewes, with the weaning weight at 3 months as the target trait.

Chromosome-level genome assembly of Guide Black-Fur sheep (Ovis aries).

Guide Black-Fur sheep (GD) is a breed of Tibetan sheep (Ovis aries) that lives in the Qinghai-Tibetan plateau region at an altitude of over 4,000 m. However, a lack of genomic information has made it difficult to understand the high-altitude adaptation of these sheep. We sequenced and assembled the GD reference genome using PacBio, Hi-C, and Illumina sequencing technologies.

Construction of a high-density genetic map and QTL localization of body weight and wool production related traits in Alpine Merino sheep based on WGR.

Background: The Alpine Merino is a new breed of fine-wool sheep adapted to the cold and arid climate of the plateau in the world. It has been popularized in Northwest China due to its superior adaptability as well as excellent production performance. Those traits related to body weight, wool yield, and wool fiber characteristics, which are economically essential traits in Alpine Merino sheep, are controlled by QTL (Quantitative Trait Loci).

Selection signatures of wool color in Gangba sheep revealed by genome-wide SNP discovery.

Background: Gangba sheep as a famous breed of Tibetan sheep, its wool color is mainly white and black. Gangba wool is economically important as a high-quality raw material for Tibetan blankets and Tibetan serge. However, relatively few studies have been conducted on the wool color of Tibetan sheep.