Previous studies have shown that miR-203 is a skin-specific microRNA (miRNA) with a profound role in skin cell differentiation. However, emerging microarray and deep sequencing data revealed that miR-203 is also expressed in embryonic skeletal muscle and myoblasts. In this study, we found that miR-203 was transiently upregulated in chicken embryos on days 10 to 16 (E10–E16) and was sharply downregulated and even not expressed after E16 in chicken embryonic skeletal muscle. Histological profiles and weight variations of embryo skeletal muscle revealed that miR-203 expression is correlated with muscle development. In vitro experiments showed that miR-203 exhibited downregulated expression during myoblast differentiation into myotubes. miR-203 overexpression inhibited myoblast proliferation and differentiation, whereas its loss-of-function increased myoblast proliferation and differentiation. During myogenesis, miR-203 can target and inhibit the expression of c-JUN and MEF2C, which were important for cell proliferation and muscle development, respectively. The overexpression of c-JUN significantly promoted myoblast proliferation. Conversely, knockdown of c-JUN by siRNA suppressed myoblast proliferation. In addition, the knockdown of MEF2C by siRNA significantly inhibited myoblast differentiation. Altogether, these data not only suggested that the expression of miR-203 is transitory during chicken skeletal muscle development but also showed a novel role of miR-203 in inhibiting skeletal muscle cell proliferation and differentiation by repressing c-JUN and MEF2C, respectively.

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A virulent infectious bronchitis virus (IBV), designated as CK/CH/GD/QY16 (referred as QY16), was isolated from a diseased chicken farm in Guangdong province, China, in 2016. The complete genome of the strain was sequenced and analyzed. The results show that the genome of QY16 consists of 27,670 nucleotides, excluding poly (A) tail, and that its genome organization is 5' UTR-1a-1b-S-3a-3b-E-M-4b-4c-5a-5b-N-6b-3' UTR-poly (A) tail. Sequence comparison among QY16 and other IBV strains was conducted and its results demonstrate that the S1 gene of QY16 has the highest nucleotide sequence identity with that of 4/91, and the other part of its genome is highly similar to that of YX10. The results of the phylogenic analysis show that the entire genome of QY16 and most of the QY16 genes are located in the same cluster as those of YX10, except for the S1 gene which is located in the same cluster with that of 4/91. It has been further confirmed by the RDP and SimPlot analysis that QY16 is a recombinant strain deriving from YX10 (as the major parental sequence) and 4/91 (as the minor parental sequence), and that the recombination occurs in a region which includes the 3'-terminal 1b sequence (85 nt) and the 5'-terminal S1 protein gene sequence (1,466 nt). The results of the vaccination-challenge test suggest that QY16 is a nephropathogenic strain of IBV and that the vaccine strains-H120 and 4/91-cannot provide effective protection against it. These results indicate that the continuing evolution of IBV strains by genetic drift and genetic recombination may lead to IBV outbreaks even among the vaccinated chickens in China.

2In pig production, insufficient feed digestion causes excessive nutrients such as phosphorus and 3 nitrogen, which are then released to the environment. To address the issue of environmental 4 emissions, we have established transgenic pigs harboring a single-copy quad-cistronic transgene 5 and simultaneously expressing three microbial enzymes, β-glucanase, xylanase, and phytase in the 6 salivary glands. All the transgenic enzymes were successfully expressed, and the digestion of non-7 starch polysaccharides (NSPs) and phytate in the feedstuff was enhanced. Fecal nitrogen and 8 phosphate outputs were reduced by 23%-46%, and growth rate improved by 23.4% (gilts) and 9 24.4% (boars) when the pigs were fed on a corn and soybean-based diet and high-NSP diet. The 10 transgenic pigs showed a 11.5%-14.5% improvement in feed conversion rate compared to the 11 age-matched wild-type littermates. These findings indicate that transgenic pigs are promising 12 resources for improving feed efficiency and reducing nutrient emissions to the environment.

2DNA methylation plays critical roles in maintaining genome stability, genomic imprinting, 2 3 3 1 abortion phenotype. Our results support a bipartite organization for DME protein, and suggest 3 2 that the N-terminal region might have regulatory function such as assisting in DNA binding and 3 3 enhancing the processivity of active DNA demethylation in heterochromatin targets. 3 4 3 5 3 6 3 Double fertilization during sexual reproduction in flowering-plants is a unique process that 3 7underlies the distinctive epigenetic reprogramming of plant gene imprinting. In the ovule, a 3 8 haploid megaspore undergoes three rounds of mitoses to produce a 7-celled, 8 nuclei embryo sac 3 9 that consists of egg, central, and accessory cells 1 . During fertilization pollen grain elongates and 4 0 delivers two sperm nuclei to the female gametophyte to fertilize the egg cell and the central cell, 4 1 respectively. The fertilized egg cell forms the embryo that marks the beginning of the subsequent 4 2 generation. Fertilization of the central cell initiates the development of endosperm that 4 3 accumulates starch, lipids, and storage proteins and serves as a nutrient reservoir for the 4 4developing embryo 2, 3 . Endosperm is the major tissue where gene imprinting takes place in plant. 5Genomic imprinting is the differential expression of the two parental alleles of a gene depending 4 6 on their parent-of-origin, and is an example of inheritance of differential epigenetic states. In 4 7Arabidopsis, MET1-mediated DNA methylation and DME demethylation are two modes of 4 8 epigenetic regulation critical for imprinted expression of many genes 4, 5, 6, 7, 8 . For example, 4 9 7 1Among them IDM1 encodes a novel histone acetylase that preferentially acetylates H3K18 and 7 2 H3K23 in vitro, and ROS1 target loci are enriched for H3K18 and K23 acetylation in vivo in an 7 3 IDM1-dependent manner 19 . Thus, IDM1 marks ROS1 target sites by acetylating histone H3 to 7 4 create a permissible chromatin environment for ROS1 function. The Arabidopsis SSRP1 7 5 (STRUCTURE SPECIFIC RECOGNITION PROTEIN1), a component of the FACT (facilitates 7 6 chromatin transcription/transaction) histone chaperone complex, has been shown to regulate 7 7 DNA demethylation and gene imprinting in Arabidopsis 20 . Linker histone H1 functions in 7 8chromatin folding and gene regulation 21, 22, 23, 24 , and was shown to interact with DME in a yeast 7 9 two-hybrid screen and in an in vitro pull-down assay 25 . Loss-of-function mutations in H1 genes 8 0 affect the imprinted expression of MEA and FWA in Arabidopsis endosperm, and impair 8 1 demethylation of their maternal alleles, suggesting that H1 might participate in the DME 8 2 5 demethylation process by interaction with DME 25 . 3Computational analysis showed that the DME/ROS1 like DNA glycosylases contain a 8 4 core with multiple conserved globular domains, and except for the well-characterized 8 5 glycosylase domain, very little is known about the function of the other domains. Here we show 8 6 that the C-terminal regio...