No abstract

BackgroundEgg production is a very important economic trait in chicken breeding, but its molecular mechanism is unclear until now. Nandan-Yao chicken (Gallus gallus domesticus) is a native breed in Guangxi province, China, which is famous for good meet quality, but low egg production. To explore the molecular regulation related egg production, high egg production (HEP) and low egg production (LEP) were divided according to the total egg number at 50 weeks, and the concentration of serum sex hormones was tested to evaluate the physiological function of ovary and uterus. RNA sequencing (RNA-Seq) was used to explore the transcriptome from the ovary and uterus of Nandan-Yao chicken. ResultsThe levels of serum sex hormone were showed that concentrations of estradiol (E2), follicle-stimulating hormone (FSH), and luteotropic hormone (LH) were very signi cantly higher in HEP compared with LEP respectively (P < 0.01), and concentrations of testosterone (T) were very signi cantly lower in HEP compared with LEP (P < 0.01), which indicated there were better physiological function in HEP compared with LEP. Analysis results of RNA-Seq showed that 901 and 2763 differentially expressed genes (DEGs) in ovary and uterus between HEP and LEP chicken, respectively. Enrichment analysis of DEGs showed that DEGs were involved signi cantly in the regulation of tight junction in the ovary (P < 0.05), while in uterus DEGs were mainly enriched signi cantly in the phagosome, ECM-receptor interaction, cell adhesion molecules (CAMs), focal adhesion, cardiac muscle contraction, cytokine-cytokine receptor interaction, and the regulation of MAPK signaling pathway (P < 0.05). Protein network interaction and function analyses revealed FN1, FGF7, SOX2,ALDOB, HSPA2 in the ovary, and UQCRH, COX5A, FN1, TGFB, ACTN1 in the uterus were key candidate genes for egg production in Nandan-Yao chicken. ConclusionsThe current study identi ed key genes and pathway contribute to improving our understanding of reproductive biology of chicken and isolating effective molecular markers that can be used for genetic selection in Nandan-Yao chicken.

Comb traits have potential economic value in the breeding of indigenous chickens in China. Identifying and understanding relevant molecular markers for comb traits can be beneficial for genetic improvement. The purpose of this study was to utilize genome-wide association studies (GWAS) to detect promising loci and candidate genes related to comb traits, namely, comb thickness (CT), comb weight (CW), comb height, comb length (CL), and comb area. Genome-wide single-nucleotide polymorphisms (SNPs) and small insertions/deletions (INDELs) in 300 Nandan-Yao chickens were detected using whole-genome sequencing. In total, we identified 134 SNPs and 25 INDELs that were strongly associated with the five comb traits. A remarkable region spanning from 29.6 to 31.4 Mb on chromosome 6 was found to be significantly associated with comb traits in both SNP- and INDEL-based GWAS. In this region, two lead SNPs (6:30,354,876 for CW and CT and 6:30,264,318 for CL) and one lead INDEL (a deletion from 30,376,404 to 30,376,405 bp for CL and CT) were identified. Additionally, two genes were identified as potential candidates for comb development. The nearby gene fibroblast growth factor receptor 2 (FGFR2)—associated with epithelial cell migration and proliferation—and the gene cytochrome b5 reductase 2 (CYB5R2)—identified on chromosome 5 from INDEL-based GWAS—are significantly correlated with collagen maturation. The findings of this study could provide promising genes and biomarkers to accelerate genetic improvement of comb development based on molecular marker-assisted breeding in Nandan-Yao chickens.

Background Egg production is a very important economic trait in chicken breeding, but its molecular mechanism is unclear until now. Nandan-Yao chicken (Gallus gallus domesticus) is a native breed in Guangxi province, China, which is famous for good meet quality, but low egg production. To explore the molecular regulation related egg production, high egg production (HEP) and low egg production (LEP) were divided according to the total egg number at 50 weeks, and the concentration of serum sex hormones was tested to evaluate the physiological function of ovary and uterus. RNA sequencing (RNA-Seq) was used to explore the transcriptome from the ovary and uterus of Nandan-Yao chicken. Results The levels of serum sex hormone were showed that concentrations of estradiol (E2), follicle-stimulating hormone (FSH), and luteotropic hormone (LH) were very significantly higher in HEP compared with LEP respectively (P < 0.01), and concentrations of testosterone (T) were very significantly lower in HEP compared with LEP (P < 0.01), which indicated there were better physiological function in HEP compared with LEP. Analysis results of RNA-Seq showed that 901 and 2763 differentially expressed genes (DEGs) in ovary and uterus between HEP and LEP chicken, respectively. Enrichment analysis of DEGs showed that DEGs were involved significantly in the regulation of tight junction in the ovary (P < 0.05), while in uterus DEGs were mainly enriched significantly in the phagosome, ECM-receptor interaction, cell adhesion molecules (CAMs), focal adhesion, cardiac muscle contraction, cytokine-cytokine receptor interaction, and the regulation of MAPK signaling pathway (P < 0.05). Protein network interaction and function analyses revealed FN1, FGF7, SOX2,ALDOB, HSPA2 in the ovary, and UQCRH, COX5A, FN1, TGFB, ACTN1 in the uterus were key candidate genes for egg production in Nandan-Yao chicken. Conclusions The current study identified key genes and pathway contribute to improving our understanding of reproductive biology of chicken and isolating effective molecular markers that can be used for genetic selection in Nandan-Yao chicken.

The antioxidant function and metabolic profiles in mice after dietary supplementation with methionine were investigated. The results showed that methionine supplementation enhanced liver GSH-Px activity and upregulated Gpx1 expression in the liver and SOD1 and Gpx4 expressions in the jejunum. Nrf2/Keap1 is involved in oxidative stress, and the western blotting data exhibited that dietary methionine markedly increased Keap1 abundance, while failed to influence the Nrf2 signal. Metabolomics investigation showed that methionine administration increased 2-hydroxypyridine, salicin, and asparagine and reduced D-Talose, maltose, aminoisobutyric acid, and inosine 5’-monophosphate in the liver, which are widely reported to involve in oxidative stress, lipid metabolism, and nucleotides generation. In conclusion, our study provides insights into antioxidant function and liver metabolic profiles in response to dietary supplementation with methionine.