ProblemThe oviduct plays an indispensable role in the formation of eggs, especially the magnum and uterus. The identification of oviduct development in different stages will help to target candidate genes and pathways in regulation of albumen and eggshell formation, as well as defense mechanism in oviduct and egg.MethodsTo identify the function differences and the molecular defense mechanism of the oviduct and egg, we performed transcriptome sequencing analysis of the magnum and uterus in 120‐d‐old and 300‐d‐old Lohmann layers, three birds in each group.ResultsWith fold changes (log2 ratio) ≥ 2 and false discovery rate (FDR) < 0.01, RNA‐Seq revealed 1,040 genes expressed differentially in the magnum and 595 genes in the uterus. By combining GO enrichment and KEGG pathway analysis, it served to show that gene activities of the magnum and uterus in prelaying chickens were more likely to concentrate on growth and development, and after egg‐laying, they were mainly inclined to enhance the substances transmembrane transport and secretion activities. We further characterized 1579 new genes, while only 803 of them were functionally annotated. A complex mixture of proteins related to defense was measured in this study. A subset of avian β‐defensins (AvBDs) and ovodefensins (OvoDs), that is, AvBD12, AvBD11, AvBD10, OvoDA1, OvoDB1, OvoDA2, OvoDA3, and OvoDBβ, was detected to express in the magnum of laying hens at high levels.ConclusionCollectively, the identification and functional analysis of these differentially expressed genes (DEGs), as well as specific expression of avian defensins, may contribute to understand the development and defense mechanisms of oviduct and eggs.

Coat color genetics successfully adapted and applied to different animal species, which provides a good demonstration of the concept of comparative genetics. In this study, we sequenced 945 bp fragments of melanocortin 1 receptor (MC1R) gene, 421 bp fragments of exon 1 of tyrosinase (TYR) gene and 266 bp fragments of exon 3 of agouti signaling protein (ASIP) gene for 250 individuals with five plumage color patterns. We detected a total of three SNPs (T398A, T637C, and G920C) in MC1R and built six haplotypes (H1-H6) based on the three SNPs. H5 and H6 haplotypes were mainly concentrated in white and grey chicken. And diplotypes H2H3 occurred in white feather and black-speckle feather with the same frequency. Moreover, a total of three SNPs (C47G, T120C, and T172C) in TYR were found and built six haplotypes (P1-P6) based on the three SNPs. Among them, haplotype P2, P3 and P6 were not occurred in black chicken, the diplotypes P1P6 and P4P6 were only distributed in white, gray and black-speckled feather. We only detected one SNP (T168C) in ASIP gene and found that genotype TT was advantage genotype in the different plumage color groups of chickens. Collectively, our study suggested an association between plumage color and genetic variation of MC1R, TYR and ASIP in chicken. Keywords Chicken • MC1R, TYR and ASIP genes • SNP • Plumage Color Chao-wu Yang and Jin-shan Ran contributed equally to this work, and shall share the first author. Yi-ping Liu and Xiao-song Jiang contributed equally to this work, and shall share the correspondence author.

The polymorphisms of MC1R gene play a crucial role in coat color variation in mammals; however, the relationship is still unclear in pigeons. In this study, we sequenced 741 bp fragment of the MC1R for 39 individuals with five plumage color patterns (gray plumage, n = 12; black plumage, n = 9; white plumage, n = 3; spotted plumage, n = 12; red plumage, n = 3). A total of three single nucleotide polymorphisms (SNPs) were detected, including G199A, G225A, and A466G, which subsequently determined four haplotypes (H1–H4). Among them, H1 is the predominant haplotype. Association analysis revealed that H1 and H3 were significantly associated with the black plumage trait (P < 0.05), while the H4 was significantly associated with gray plumage trait (P < 0.05). Furthermore, only diplotype H1H1 was significantly associated with black and gray traits of pigeons. Collectively, our study suggested an association between genetic variation of MC1R and plumage color in pigeon.

The proliferation and differentiation of skeletal muscle satellite cells (SMSCs) play an important role in the development of skeletal muscle. Our previous sequencing data showed that miR-21-5p is one of the most abundant miRNAs in chicken skeletal muscle. Therefore, in this study, the spatiotemporal expression of miR-21-5p and its effects on skeletal muscle development of chickens were explored using in vitro cultured SMSCs as a model. The results in this study showed that miR-21-5p was highly expressed in the skeletal muscle of chickens. The overexpression of miR-21-5p promoted the proliferation of SMSCs as evidenced by increased cell viability, increased cell number in the proliferative phase, and increased mRNA and protein expression of proliferation markers including PCNA, CDK2, and CCND1. Moreover, it was revealed that miR-21-5p promotes the formation of myotubes by modulating the expression of myogenic markers including MyoG, MyoD, and MyHC, whereas knockdown of miR-21-5p showed the opposite result. Gene prediction and dual fluorescence analysis confirmed that KLF3 was one of the direct target genes of miR-21-5p. We confirmed that, contrary to the function of miR-21-5p, KLF3 plays a negative role in the proliferation and differentiation of SMSCs. Si-KLF3 promotes cell number and proliferation activity, as well as the cell differentiation processes. Our results demonstrated that miR-21-5p promotes the proliferation and differentiation of SMSCs by targeting KLF3. Collectively, the results obtained in this study laid a foundation for exploring the mechanism through which miR-21-5p regulates SMSCs.

Myeloid differentiation primary response gene 88 (MYD88), a universal adapter protein, plays an important role in activating the nuclear factor-κB (NF-κB) and regulating the expression of proinflammatory genes like tumor necrosis factor (TNF) and interleukin-1 (IL-1), which were highly involved in Salmonella Pullorum infection. To detect the relationship between polymorphisms of the MyD88 gene and Salmonella Pullorum disease, we screened the coding region (CDS) of the MYD88 gene by DNA pool construction and sequencing based on case-control study. Eight single nucleotide polymorphisms (SNPs) in the sequenced fragment (5 exons), 7 known loci and one novel mutation named G4810372T (SNP8), were found in the fifth exon. In addition, we found 7 nonsynonymous substitutions. The allele frequency of only one SNP, g.4810191C > T (SNP1), was significantly different (P < 0.05) between case and control groups. The genotype frequencies of SNP1 (g.4810191C > T) and SNP3 (g.4810257G > T) were of significant difference between the case and the control groups (P < 0.05). Collectively, SNPs of the MyD88 gene were significantly associated with susceptibility to Salmonella Pullorum infection, which can be used as a disease-resistant marker in chicken. These results provided a theoretical basis for future research on chicken breeding by marker-assisted selection.