Preimplantation development refers to the early embryonic development between fertilization and implantation. During this short developmental window (4.5 days of mouse), a series of morphological and developmental changes take place. In morphology, three important changes occurred during preimplantation development in mouse embryos: compaction and polarity at 8-cell stage; inner cell mass and trophectoderm differentiation at early blastocyst stage; epiblast and primitive endoderm segregation at late blastocyst stage. In developmental biology, chromatin reprogramming, degradation of maternal factor, and embryo genomic activation take place after fertilization. Taken preimplantation embryos of mouse as an example, the present review aims to highlight the regulatory mechanisms responsible for the change of embryo morphology, and related signaling pathways of early embryonic cell differentiation, which are essential for the lineage specification. Understanding the fundamental mechanisms underlying the preimplantation development would greatly enhance our capability to improve reproductive performance of domestic animals or increase the efficiency of assisted reproductive technologies in mammals.

Fungi are the major microbes to exploit fiber degrading enzymes. Anaerobic fungi possess hydrogenosomes and cellulosomes to improve their energy supply in anaerobic environment, and their thick cell wall or spore-like structure help them adapt adverse environment. Animal host phylogeny and diet exert the most significant role in shaping anaerobic fungal diversity and community structure. Molecular marker technology based on ribosomal 18S/28S rRNA genes and internal spacer region (ITS) provides a more precise means for the research of anaerobic fungi quantity and diversity, and the 28S rDNA D1/D2 is the preferred region for anaerobic fungal next generation sequencing. Due to limited databases for fungus and methods for obtaining enough fungal DNA/RNA from digestive tract contents for metagenomic/metatranscriptomic analyses, little work is available on fungal physiology and function of gastrointestinal tract using advanced omics techniques. However, application of these techniques will be key to deepen our understanding of the ecological role of fungi in gastrointestinal tract.

Nowadays, coincided with more and more profound studies on intestinal microbiota, people are increasingly aware of its fundamental role in human and animal health. However, current studies mainly focused on nutritional metabolic disease, chronic and autoimmune diseases, little attention has been paid to its role in infectious diseases, particularly in viral diseases. Until very recently, researchers have begun to systematically study the interaction between intestinal bacteria and viruses. With the advance of relevant researches, the role of intestinal 、bacteria has been explored in viral invasion, pathogenicity and antiviral immunity；however, the mechanisms are largely unrevealed yet. Thus, in this article, we briefly reviewed recently highlighted advances in virus-bacteria interaction, especially elucidated relative mechanisms by which enteroviruses utilize bacteria to enhance viral invasion in vivo. In general, these mechanisms are segregated into two main categories: 1) direct facilitation of viral infection, including virion stabilization and enhancement of viral binding to host target cells; 2) indirect suppression of the antiviral immune responses in a manner of promoting in vivo replication. Discussionon mechanisms of enteroviruses exploiting intestinal bacteria for their invasion will be conducive to comprehensive understanding viral pathogenesis, elucidating virus-bacteria interactions and illuminating molecular mechanisms of enteroviruses evading host mucosal immunity. It can also provide novel insights and scientific basis into the development of novel enteroviral vaccines and associated adjuvants, as well as novel antiviral therapeutic approaches.

Porcine epidemic diarrhea virus (PEDV) is a causative agent of acute, highly contagious porcine epidemic diarrhea (PED). It infects pigs of all ages and results in high mortality rates particularly in suckling piglets. Current vaccines can not provide efficient protection to infected piglets. Thus, developing safer and more efficacious vaccines is fundamental to the control of PEDV. Meanwhile, it is of significance in establishing sensitive and efficient serological assays for clinical diagnosis of PEDV infection as well as the surveillance and evaluation of humoral responses at post-vaccination. In this review, we summarized the current serological assays and discussed the antibody kinetics at post-infection or vaccination, aiming to provide references to the diagnoses and control of PEDV.

Using gene editing technology based on CRISPR/Cas9n system and somatic cell nuclear transfer technology, we constructed a plasmid of two sgRNAs and Cas9 nickase, and green fluorescent protein (GFP) in the same vector followed by transient transfection of porcine fibroblasts. By flow cytometry, the cells expressing GFP were selected, and the GFP positive cells were cultured to single cells. The CD163 edited clones were screened through polymerase chain reaction (PCR) and DNA sequencing, and the positive rate was as high as 90% (18/20). Somatic cell nuclear transfer and embryo transfer were carried out using cells with edited CD163, and two CD163 gene-edited cloned offsprings were obtained.

To develop a new and effective method for detection of follicle-stimulating hormone (FSH) bioactivity, porcine follicular granulosa cells were used as experimental materials, and expression of genes in FSH-treated group (40 mIU/mL) and blank control group was compared by transcriptome sequencing to identify FSH-regulated candidate genes. Meanwhile, real-time fluorescent quantitative polymerase chain reaction was used to validate significantly upregulated genes after FSH treatments, and the porcine follicular granulosa cells were treated further by FSH dose gradients (0, 20, 40, 60, 80 and 100 mIU/mL). The results indicated that the expressions of OLR1, LHCGR, SCARA5 and S100A12 increased in a FSH dose-dependent manner. In addition, the expression of these four genes was determined in FSH dose gradients (0, 1, 3, 9, 27, 81, 243 and 729 mIU/mL), and the results showed that the correlation coefficient between the expression of LHCGR and dose gradient of FSH was close to 1 (R²=0.982) in the FSH dose range of 0-243 mIU/mL. In summary, LHCGR expression has a linear relationship with FSH dose, which may be helpful to develop a novel method for biological value detection of FSH.

To investigate the effects of dietary leucine supplementation on endoplasmic reticulum (ER) stress in the liver of early-weaning piglets, we explored the morphology of liver cells, expression pattern of ER stress-associated proteins, and effects on ER stress induced by early weaning under leucine treatment using transmission electron microscopy (TEM), nucleo-cytoplasmic fractionation and immunoblotting assays. The results showed that in the early weaning-induced ER stress model, the diameter of ER in the liver cells derived from 14-day-old early-weaning piglets was increased compared with the normal group, while the structure of ER was disordered, and the expression level of ER stress-associated protein XBP1 in the nucleus of liver cells was significantly up-regulated (P＜0.05). In the HepG2 cells cultured in vitro, the ER stress-associated proteins ATF4 and cleaved ATF6α were significantly up-regulated (P＜0.05) with the absence of either glucose or leucine in the medium, while after re-stimulation with leucine, ATF4 expression was further up-regulated in the nucleus of HepG2 (P＜0.05). By feeding weaning piglets with diets containing different levels of leucine, we found that dietary leucine levels had no significant effect on the expression of ATF4 and cleaved ATF6α in the nucleus of liver cells derived from 21-day-old non-weaning piglets (P＞0.05). After weaning 24 h, the expression of ATF4 in the nucleus of liver cells derived from piglets fed with diet containing 2.10% leucine was significantly higher than that of 1.66% leucine group (P＜0.05). In summary, early weaning can induce ER stress in the liver cells of piglets, and leucine plays crucial roles in regulating ER stress induced by early weaning.

To investigate the effects of low-dose compound organic trace minerals (Fe, Cu, Mn and Zn) on growth performance, serum trace mineral contents, antioxidative indexes and fecal trace element excretion in fattening pigs with different trace element feeding backgrounds, a total of 192 Duroc×Landrace×Large White pigs with similar body mass [(61.2±4.4) kg] and identical parity were selected and divided into four groups with four replicates each (12 pigs per pen) in a 2×2 factorial design. The first factor was feeding background (background I: commercial dosages of inorganic Fe, Cu, Mn, Zn were fed to suckling pigs, nursery pigs and growing pigs; background O: organic Fe, Cu, Mn, Zn at 50%, 30% and 20% commercial recommended levels were fed tosuckling pigs, nursery pigs and growing pigs, respectively), while the second factor was dietary treatment [inorganic trace mineral (ITM): basal diet＋inorganic Fe, Cu, Mn, Zn of 100, 20, 25, 100 mg/kg, respectively; organic trace mineral (OTM): basal diet+organic Fe, Cu, Mn, Zn of 20, 4, 5, 20 mg/kg, respectively). The feeding period lasted for 82 days, with 38 days for early finishing stage and 44 days for late finishing stage. The results showed that: 1) The feeding background and dietary treatment both had no significant influences on the growth performance of fattening pigs (P＞0.05) during the whole period. 2) The OTM diet increased the Zn content (P＜0.05) and Mn-superoxide dismutase (SOD) activity (P=0.05) in the serum of fattening pigs at early finishing stage, and decreased the malonaldehyde (MDA) content (P=0.05). 3) The OTM diet significantly reduced the Fe, Mn, Cu and Zn emissions (P＜0.05) in manure during whole phases; while the background O significantly decreased the Fe emission at the early finishing stage and Fe, Cu, Zn emissions at the late finishing stage in manure (P＜0.05). The background O and OTM had an interaction (P＜0.05) on reducing Fe content in fattening pig manure at the late finishing stage. The above results indicate that the addition of low-dose organic trace minerals in the basal diet can significantly reduce the heavy metal emissions in the fattening pig manure, and improve antioxidant level of growing- fattening pigs without affecting its growth performance; while feeding background at early growth stages can also significantly influence the heavy metal emissions in fattening pigs.

To investigate the effects of Clostridium butyricum on serum biochemical indices, antioxidant function and intestinal microbiota in weaned piglets, a total of 360 25-day-old healthy“Duroc×Landrace×Yorkshire” weaned piglets with the average body mass of (6.24±0.32) kg were selected and randomly divided into five groups. Each group had four replicates with 18 piglets per replicate. Piglets in the control group (CG) were fed with a corn-soybean type basal diet, and those in the experimental groups (EG) were fed with experimental diet, which added 250, 500, 1 000 and 2 000 mg/kg Clostridium butyricum in basal diet for 30 days, respectively. The results showed as follows: 1) No significant difference was found between the CG and EG on the serum biochemical indices such as glutamic oxaloacetic transaminase (GOT), glutamate pyruvic transaminase (GPT), blood urea nitrogen (BUN) and alkaline phosphatase (AKP) (P＞0.05). Compared with the CG, the serum total protein (TP) level in the EG was increased by 10.45% (P＞0.05), 17.64% (P＜0.05), 15.24% (P＜0.05) and 17.54% (P＜0.05), respectively; the concentrations of serum albumin (ALB) in the EG were increased by 0.78% (P＞0.05), 3.80% (P＞0.05), 3.50% (P＞0.05) and 5.52% (P＜0.05), respectively. 2) The concentration of serum catalase (CAT) in the 1 000 mg/kg group was increased by 65.87% (P＜0.05). The total antioxidant capacity (TAOC) level of liver in the 500 mg/kg group was increased by 13.14% (P＜0.05). 3) The diet supplemented with Clostridium butyricum significantly decreased the number of Escherichia coli and Salmonella in the cecum of weaned piglets (P＜0.05 or P＜0.01). Compared with the CG, the number of Lactobacillus and Bifidobacterium in the EG increased at different degrees (P＞0.05). The results indicate that the diet supplemented with Clostridium butyricum can alleviate oxidative stress during weaning and inhibit the growth of harmful intestinal bacteria of weaned piglets. The optimal dietary Clostridium butyricum of weaned piglets at the age of 25 to 55 days is 500 mg/kg.