Avian species have a unique integument covered with feathers. Skin morphogenesis is a successive and complex process. To date, most studies have focused on a single developmental point or stage. Fewer studies have focused on whole transcriptomes based on the time-course of embryo integument development. To analyze the global changes in gene expression profiles, we sequenced the transcriptome of chicken embryo skin samples from day 6 to day 21 of incubation and identified 5830 differentially expressed genes (DEGs). Hierarchical clustering showed that E6 to E14 is the critical period of feather follicle morphogenesis. According to Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of the DEGs, two kinds of Wnt signaling pathways (a canonical pathway and a non-canonical pathway) changed during feather follicle and feather morphogenesis. The gene expression level of inhibitors and ligands related to the Wnt signaling pathway varied significantly during embryonic development. The results revealed a staggered phase relationship between the canonical pathway and the non-canonical pathway from E9 to E14. These analyses shed new light on the gene regulatory mechanism and provided fundamental data related to integument morphogenesis of chickens.

Cell types have been established during organogenesis based on early mouse embryos. However, our understanding of cell types and molecular mechanisms in the early embryo development of Mongolian sheep has been hampered. This study presents the first comprehensive single-cell transcriptomic characterization at E16 in Ujumqin sheep and Hulunbuir short-tailed sheep. Thirteen major cell types were identified at E16 in Ujumqin sheep, and eight major cell types were identified at E16 in Hulunbuir short-tailed sheep. Function enrichment analysis showed that several pathways were significantly enriched in the TGF-beta signaling pathway, the Hippo signaling pathway, the platelet activation pathway, the riboflavin metabolism pathway, the Wnt signaling pathway, regulation of the actin cytoskeleton, and the insulin signaling pathway in the notochord cluster. Glutathione metabolism, glyoxylate, and dicarboxylate metabolism, the citrate cycle, thyroid hormone synthesis, pyruvate metabolism, cysteine and methionine metabolism, thermogenesis, and the VEGF signaling pathway were significantly enriched in the spinal cord cluster. Steroid biosynthesis, riboflavin metabolism, the cell cycle, the Hippo signaling pathway, the Hedgehog signaling pathway, the FoxO signaling pathway, the JAK-STAT signaling pathway, and the Wnt signaling pathway were significantly enriched in the paraxial mesoderm cluster. The notochord cluster, spinal cord cluster, and paraxial mesoderm cluster were found to be highly associated with tail development. Pseudo-time analysis demonstrated that the mesenchyme can translate to the notochord in Ujumqin sheep. Molecular assays revealed that the Hippo signaling pathway was enriched in Ujumqin sheep. This comprehensive single-cell map revealed previously unrecognized signaling pathways that will further our understanding of the mechanism of short-tailed sheep formation.

Dosage compensation is a mechanism first proposed by Susumu Ohno, whereby X inactivation balances X gene output between males (XY) and females (XX), while X upregulation balances X genes with autosomal gene output. These mechanisms have been actively studied in Drosophila and mice, but research regarding them lags behind in domestic species. It is unclear how the X chromosome is regulated in the sheep male germline. To address this, using single-cell RNA sequencing, we analyzed testes in three important developmental stages of sheep. We observed that the total RNA per cell from X and autosomes peaked in SSCs and spermatogonia and was then reduced in early spermatocytes. Furthermore, we counted the detected reads per gene in each cell type for X and autosomes. In cells experiencing dose compensation, close proximity to MSL (male-specific lethal), which is regulated the active X chromosome and was observed. Our results suggest that there is no dose compensation in the pre-meiotic germ cells of sheep testes and, in addition, MSL1 and MSL2 are expressed in early germ cells and involved in regulating mammalian X-chromosome inactivation and activation.

The in vitro granulosa cell (GC) model presents a valuable tool to explore antral follicle development. A full understanding of the reasons and blocking methods that occur during in vitro luteinization of sheep GCs, stimulated by serum culture, is a complex goal that has not been completely achieved. Herein, the phenomenon and causes of GC differentiation, as well as the methods for inhibiting luteinization in an in vitro culture system, were investigated by immunofluorescence, Western blot, RT-qPCR, and ELISA techniques. The results reveal that, when compared to fresh GCs, FSHR protein levels in primary GCs significantly decreased in serum-containing media, while STAR protein levels significantly increased, implying that sheep GCs can differentiate in serum-containing media. LH concentrations were significantly greater in serum-containing media compared to serum-free media. The LH receptor (LHR) mRNA expression in primary-generation GCs steadily increased with longer culture times, indicating that LH-LHR signaling leads to GC luteinization in vitro. In primary and second-generation GCs, 180 nmol/L BAY-899, an LHR-specific antagonist, significantly increased FSHR protein expression, reduced STAR protein synthesis, and inhibited P4 secretion within 48 h of in vitro culture compared to controls. BAY-899 showed no adverse effects on fifth-generation GCs growth, implying that BAY-899 can inhibit GC luteinization while not affecting cell proliferation. In conclusion, this study found that the LHR antagonist BAY-899 can preserve the features of sheep GCs in vitro by suppressing the spontaneous luteinization process caused by LH-LHR signaling, which has a key methodological implication for studying the mechanics of antral follicle formation in vivo.

Background: The Alxa bactrian camel, as one of the primary breeds in China, contributes significantly to the local dietary structure as a crucial meat source. However, the existing analysis and research on the quality and chemical composition of Alxa bactrian camel meat lack a comprehensive and systematic approach, leading to a substantial lag in the development and utilization of local camel meat products. Methods: To investigate the meat quality characteristics of Alxa bactrian camels, 48 individuals were randomly selected from Desert, Gobi, Desert steppe and Mountainous areas based on their ecological environment. Their meat quality characteristics and chemical compositions were analyzed in two age groups (3~4 ,7~8 years old). Result: The shear force, fat, energy, iron, manganese, methionine, myristic acid, palmitic acid, vitamin E and hypoxanthine contents of camel meat significantly increased with age, while moisture, glutamic acid, glycine, proline, stearic acid, linoleic acid, cis-11,14,17-dodecatrienoic acid and cis-13,16-docosa-2-dienoic acid contents decreased with age. In comparison to the meat of grass-feeding livestock such as cattle and sheep, Alxa bactrian camel meat is characterized by low cholesterol, low fat, high calcium, high sodium, selenium enrichment and high L-carnitine.