Exosomes are a subset of nano-sized extracellular vesicles originating from endosomes. Exosomes mediate cell-to-cell communication with their cargos, which includes mRNAs, miRNAs, lncRNAs, and circRNAs. Exosomal RNAs have cell specificity and reflect the conditions of their donor cells. Notably, their detection in biofluids can be used as a diagnostic marker for various diseases. Exosomal RNAs are ideal biomarkers because their surrounding membranes confer stability and they are detectable in almost all biofluids, which helps to reduce trauma and avoid invasive examinations. However, knowledge of exosomal biomarkers remains scarce. The present review summarizes the biogenesis, secretion, and uptake of exosomes, the current researches exploring exosomal mRNAs, miRNAs, lncRNAs, and circRNAs as potential biomarkers for the diagnosis of human diseases, as well as recent techniques of exosome isolation.

Silage is rich in nutrients, which can make up for the lack of seasonal roughage, and has a certain promotion effect on the intensive feeding of ruminants. In addition, silage can maintain the rumen function of ruminants to a certain extent and reduce the risk of rumen acidosis and abomasum translocation. The purpose of this study was to investigate the effects of the mixed silage of Chinese cabbage waste and rice straw (mixed silage) on antioxidant performance, rumen microbial population, and fermentation metabolism of Hu sheep. The 16 healthy Hu sheep (eight rams and eight ewes, 39.11 ± 1.16 kg, 5.5 months) were randomly divided into two groups (the control group and the mixed silage group) with eight animals (four rams and four ewes) in each group. The control group was fed with farm roughage (peanut seedlings, corn husk, and high grain shell) as forage, and the mixed silage group was fed with the mixed silage as forage. The results showed that the mixed silage had no effect on the growth performance of Hu sheep (p > 0.05). Ruminal butyric acid, total volatile fatty acids (TVFA), and ammonia nitrogen (NH₃-N) concentration in the mixed silage group were increased, whereas the pH was decreased (p < 0.05). The blood and rumen total antioxidants capacity (T-AOC) concentration in the mixed silage group was higher, and the malondialdehyde (MDA) content in rumen, serum, liver, and kidney was lower than that in the control group (p < 0.05). PCoA and ANOSIM results of Illumina sequencing indicated that the mixed silage affected the bacterial composition of the rumen microbes. The mixed silage increased the proportion of Prevotellaceae UCG-004 which was in a positive correlation with Vitamin C (Vc). In addition, PICRUSt functional prediction analysis showed that ascorbate and aldarate metabolism were up-regulated in the mixed silage group (p < 0.05). In conclusion, higher contents of V_C and acid detergent fiber (ADF) in the mixed silage were beneficial to the growth and reproduction of Prevotellaceae UCG-004, resulting in increased production of the butyric acid significantly upregulated the metabolism of ascorbate and aldarate metabolism, thereby improving the antioxidant properties of Hu sheep.

Background: There are abundant sheep breed resources in the Xinjiang region of China attributing to its diverse ecological system, which include several high-litter size sheep populations. Previous studies have confirmed that the major high prolificacy gene cannot be used to detect high litter size. Our research team found a resource group in Pishan County, southern Xinjiang. It showed high fertility with an average litter size of two to four in one birth, excellent breast development, and a high survival rate of lambs. In the present study, we used this resource as an ideal sample for studying the genetic mechanisms of high prolificacy in sheep. Methods: Indigenous sheep populations from Xinjiang, with different litter sizes, were selected for the research, and specific-locus amplified fragment sequencing (SLAF-seq) technology was used to comprehensively screen single nucleotide polymorphisms (SNPs) from the whole genome that may cause differences in litter size. Novel genes associated with litter size of sheep were detected using genome-wide association studies (GWAS), providing new clues revealing the regulation mechanism of sheep fecundity. Candidate genes related to ovulation and litter size were selected for verification using Kompetitive Allele Specific polymerase chain reaction (KASP) cluster analysis. Results: We identified 685,300 SNPs using the SLAF-seq technique for subsequent genome-wide analysis. Subsequently, 155 SNPs were detected at the genome-wide level. Fourteen genes related to sheep reproduction were notated: COIL, SLK, FSHR, Plxna3, Ddx24, CXCL12, Pla2g7, ATP5F1A, KERA, GUCY1A1, LOC101107541, LOC101107119, LOC101107809, and BRAF. Based on literature reports, 30 loci of seven genes and candidate genes (CXCL12, FSHR, SLK, GUCY1A1, COIL, LOC101107541, and LOC101107119) related to ovulation and litter size were selected for verification using KASP cluster analysis. Among them, nine loci of three genes were successfully genotyped. Three loci of FSHR (GenBank ID: 443299, g. 75320741G>A site), GUCY1A1 (GenBank ID: 101110000, g. 43266624C>T site), and COIL (GenBank ID: 101123134, g. 7321466C>G site) were found to be significantly or extremely significantly associated with litter size. These three loci are expected to be used as molecular markers to determine differences in litter size in sheep.

Precision dietary interventions (e.g., altering proportions of dietary protein fractions) has significant implications for the efficiency of nutrient use in ruminants, as well as lowering their environmental footprint, specifically nitrogen (N) emissions. Soluble protein (SP) is defined as the protein fraction that is rapidly degraded in the rumen (e.g., non-protein N and true protein), and our previous study found that regulating SP levels could improve N efficiency in Hu sheep. Thus, the present study was conducted to explore in vitro how protein fractions with different SP levels modulate the rumen microbial community and its association with N metabolism. Four dietary treatments with different SP proportions and similar crude protein (CP) content (~14%) were formulated (% of CP): 20 (S20), 30 (S30), 40 (S40) and 50 (S50). Results showed that NH₃-N content increased with increasing SP levels at 4, 12 and 24 h; TVFA, acetate, propionate and valerate were higher in S30 and S40 (p < 0.05) and had quadratic effects (p < 0.05). Moreover, dry matter digestibility (DMD) and N digestibility (ND) were all decreased with S20 and S50 (p < 0.05). The S30 and S40 treatments increased the abundance of Bacteroidetes and Prevotella (Prevotella_ruminicola) but decreased the abundance of Firmicutes and Proteobacteria (p < 0.05). Bacterial pathways related to amino acid and fatty acid metabolism also were enriched with S30 and S40. The abundance of Entodinium was increased with S30 and S40 and had a positive correlation with Prevotella, and these two genera also played an important role in N metabolism and VFA synthesis of this study. In conclusion, bacterial and protozoal communities were altered by the level of SP (% of CP), with higher SP levels (~50% of CP) increasing the microbial diversity but being detrimental to rumen N metabolism.

Fat tail is one of the most important domesticated characteristics in sheep; however its molecular mechanism is poorly understood. Here we took small-tailed F2 hybrid of wild Argali sheep and typical fat-tailed Bashby sheep as research object. First, histological analysis revealed that the mean diameter and area in tail and subcutaneous fat cells, and surface density in tail fat in Bashby sheep were significantly larger than that in F2 sheep, and surface density of fat in subcutaneous fat in Bashby sheep was significantly lower than that in F2 sheep. Second, 873 differentially expressed genes (DEGs) of tail fat between Bashby and F2 sheep were identified by RNA-seq. Third, the tissue expression profile and relative expression difference between Bashby and F2 sheep of 7 of 873 DEGs were analyzed by RT-PCR. SCD, ESR1, EMR1, PHYH, STAT3 and GPAM genes were highly expressed in fat, muscle and liver, and ALDH1A1 were highly expressed in small intestine. In addition, the expressions of SCD, PHYH and CPAM genes in tail fat of F2 sheep were lower than that of Bashby sheep, while the expression patterns of ESR1 and EMR1 were reversed. Our findings will not only help understand molecular mechanism of fat tail, but also provide theoretical material in sheep evolution.