Naive hypomethylated embryonic pluripotent stem cells (ESCs) are developmentally closest to the preimplantation epiblast of blastocysts, with the potential to contribute to all embryonic tissues and the germline, excepting the extra-embryonic tissues in chimeric embryos. By contrast, epiblast stem cells (EpiSCs) resembling postimplantation epiblast are relatively more methylated and show a limited potential for chimerism. Here, for the first time, we reveal advanced pluripotent stem cells (ASCs), which are developmentally beyond the pluripotent cells in the inner cell mass but with higher potency than EpiSCs. Accordingly, a single ASC contributes very efficiently to the fetus, germline, yolk sac and the placental labyrinth in chimeras. Since they are developmentally more advanced, ASCs do not contribute to the trophoblast. ASCs were derived from blastocysts in two steps in a chemically defined medium supplemented with Activin A and basic fibroblast growth factor, followed by culturing in ABCL medium containing ActA, BMP4, CHIR99021 and leukemia inhibitory factor. Notably, ASCs exhibit a distinct transcriptome with the expression of both naive pluripotency genes, as well as mesodermal somatic genes; Eomes, Eras, Tdgf1, Evx1, hand1, Wnt5a and distinct repetitive elements. Conversion of established ESCs to ASCs is also achievable. Importantly, ASCs exhibit a stable hypermethylated epigenome and mostly intact imprints as compared to the hypomethylated inner cell mass of blastocysts and naive ESCs. Properties of ASCs suggest that they represent cells at an intermediate cellular state between the naive and primed states of pluripotency.

The active and inactive X chromosomes have distinct epigenetic marks in somatic nuclei, which undergo reprogramming after transplantation into oocytes. We show that, despite the disappearance of Xist RNA coating in 30 min, the epigenetic memory of the inactive X persists with the precocious appearance of histone H3 trimethylation of lysine 27 (H3‐3meK27), without the expected colocalization with Eed/Ezh2. Subsequently, Xist re‐appears on the original inactive X, and the silent Xist on the active X undergoes re‐activation, resulting in unusual biallelic Xist RNA domains. Despite this abnormal Xist expression pattern, colocalization of H3‐3meK27 and Eed is thereafter confined to a single Xist domain, which is presumably on the original inactive X. These epigenetic events differ markedly from the kinetics of preferential paternal X inactivation in normal embryos. All the epigenetic marks on the X are apparently erased in the epiblast, suggesting that the oocyte and epiblast may have distinct properties for stepwise programming of the genome.

Prolificacy is a crucial characteristic of livestock, particularly for species such as sheep that have many births. The objectives of this study were as follows: (1) to investigate the genetic diversity of the 13 new and 7 known variants in the BMPRIB, GDF9, BMP15, LEPR, and B4GALNT2 genes in Ujimqin (UM), the F1 population of Dorper × Ujimqin crossbred (DPU), the F1 population of Suffolk × Ujimqin crossbred (SFKU), Sonid sheep (SN), Tan sheep (Tan), Hu sheep (Hu), and Small-tailed Han sheep (STH) sheep breeds/populations; (2) to perform an association analysis of the above 20 variants with litter size in 325 UM, 304 DPU, and 66 SFKU sheep populations; (3) to compare the frequencies of the litter-size-related alleles of these 20 variants among 8 sheep breeds/populations (the above seven sheep breeds + Mongolia sheep breed). With the use of the Sequenom MassARRAY^®SNP assay technology, these 20 mutations were genotyped. The association analysis results showed that the c.746A>G (FecB) mutation in BMPR1B was significantly associated with the litter size of UM and DPU, the c.994A>G (FecG^A) in GDF9 was significantly associated with the litter size of SFKU, and the c.31_33CTTinsdel (B1) in BMP15 was significantly associated with the litter size of UM. Our findings might provide valuable genetic markers for expanding sheep litter sizes.

The disease resistance phenotype is closely related to immunomodulatory function and immune tolerance and has far-reaching implications in animal husbandry and human health. Microbes play an important role in the initiation, prevention, and treatment of diseases, but the mechanisms of host–microbiota interactions in disease-resistant phenotypes are poorly understood. In this study, we hope to uncover and explain the role of microbes in intestinal diseases and their mechanisms of action to identify new potential treatments. First, we established the colitis model of DSS in two breeds of sheep and then collected the samples for multi-omics testing including metagenes, metabolome, and transcriptome. Next, we made the fecal bacteria liquid from the four groups of sheep feces collected from H-CON, H-DSS, E-CON, and E-DSS to transplant the fecal bacteria into mice. H-CON feces were transplanted into mice named HH group and H-DSS feces were transplanted into mice named HD group and Roseburia bacteria treatment named HDR groups. E-CON feces were transplanted into mice named EH group and E-DSS feces were transplanted into mice in the ED group and Roseburia bacteria treatment named EDR groups. After successful modeling, samples were taken for multi-omics testing. Finally, colitis mice in HD group and ED group were administrated with Roseburia bacteria, and the treatment effect was evaluated by H&E, PAS, immunohistochemistry, and other experimental methods. The difference in disease resistance of sheep to DSS-induced colitis disease is mainly due to the increase in the abundance of Roseburia bacteria and the increase of bile acid secretion in the intestinal tract of Hu sheep in addition to the accumulation of potentially harmful bacteria in the intestine when the disease occurs, which makes the disease resistance of Hu sheep stronger under the same disease conditions. However, the enrichment of harmful microorganisms in East Friesian sheep activated the TNFα signalling pathway, which aggravated the intestinal injury, and then the treatment of FMT mice by culturing Roseburia bacteria found that Roseburia bacteria had a good curative effect on colitis. Our study showed that in H-DSS-treated sheep, the intestinal barrier is stabilized with an increase in the abundance of beneficial microorganisms. Our data also suggest that Roseburia bacteria have a protective effect on the intestinal barrier of Hu sheep. Accumulating evidence suggests that host–microbiota interactions are associated with IBD disease progression.