Avian leukosis virus subgroup K (ALV-K) is a new subgroup of avian leukosis virus (ALV) that was first identified in Chinese native chickens in recent years. To further understand the molecular epidemiology and evolutionary diversity of ALV-K, this study investigated the molecular epidemiology of 73,664 chicken plasma samples collected from Jiangxi native chicken flocks. The results showed that ALV-J was the most predominant ALV subtype in Jiangxi native chickens, with a high positivity rate of 4.34%. From 2021 to 2023, there was a gradual upward trend in the proportion of positive numbers of ALV-K among ALV-positive samples, and there was a trend of outbreaks. ALV-J and ALV-K were the main co-infection patterns. Genetic evolutionary analysis based on ALV-K gp85 gene showed that the isolated ALV-K in this study were distributed in various branches of the evolutionary tree with genetic diversity. The homology results showed that the amino acid homology of the isolated ALV-K gp85 gene ranged from 33.9 to 88.1% with the reference strains of subtypes A, B, C, D, E, and J, and from 91.9 to 100% with the other ALV-K reference strains. Multiple mutations were present in the ALV-K gp85, and especially significant mutations were found in the highly variable region hr2. The results of ALV-K replication efficiency showed that the replication efficiency of ALV-K was significantly lower than that of ALV-J. These results enriched the genome sequence data of ALV-K in Chinese geoducks, and laid the foundation for further research on the pathogenesis and prevention of ALV-K.

The large amount of melanin deposited in Taihe black-boned silky fowl and other black-boned chicken breeds is a highly valued trait due to its desirable nutritional and functional properties, such as antiaging, immune-enhancing, and antifatigue properties. To identify the candidate genes and pathways potentially responsible for melanogenesis in Taihe black-boned silky fowl, digital gene expression tag (DGE-tag)-based transcriptome analyses were performed for 2 groups: wild-type Taihe black-boned silky fowl (TH-1245) vs. mutated Taihe black-boned silky fowl (BY-1245) and TH-1245 vs. wild-type Yugan black-boned chicken (YG-1245). In total, 430 and 765 differentially expressed genes (DEGs) were identified and 13 DEGs displaying different gene expression patterns between the 2 groups were considered valuable for further investigation, such as ANKRD1, MYOZ2, and MYOD1. Furthermore, 6 functionally grouped networks composed of 36 significant GO terms, mainly involved in muscle-related and signaling-related biological processes, were screened by functional enrichment network analysis. In addition, protein-protein interaction (PPI) network analysis identifies 2 top clusters containing 20 hub genes for 2 comparison groups. MYL1 and RPS14 were considered the most potential candidate genes among all hub genes. The Gene Set Enrichment Analysis (GSEA) results showed that the terms and pathways, such as muscle system process, arachidonic acid metabolism, melanogenesis, and tyrosine metabolism, may play important roles in the melanogenesis and further investigations were needed to clarify the relationships between these pathways and melanin. Overall, these results are helpful for furthering our understanding of melanogenesis in breast muscle of Taihe black-boned silky fowl and Yugan black-boned chicken.

Objective: Rutin, also called vitamin P, is a flavonoids from plants. Previous studies have indicated that rutin can alleviate the injury of tissues and cells by inhibiting oxidative stress and ameliorating inflammation. There is no report on the protective effects of rutin on goat rumen epithelial cells (GRECs) at present. Hence, we investigated whether rutin can alleviate lipopolysaccharide (LPS)-induced damage in GRECs.Methods: GRECs were cultured in basal medium or basal medium containing 1 μg/mL LPS, or 1 μg/mL LPS and 20 μg/mL rutin. Six replicates were performed for each group. After 3-h culture, the GRECs were harvested to detect the relevant parameters.Results: Rutin significantly enhanced the cell activity (p<0.05) and transepithelial electrical resistance (TEER) (p<0.01) and significantly reduced the apoptosis rate (p<0.05) of LPSinduced GRECs. Rutin significantly increased superoxide dismutase, glutathione peroxidase, and catalase activity (p<0.01) and significantly decreased lactate dehydrogenase activity and reactive oxygen species and malondialdehyde (MDA) levels in LPS-induced GRECs (p<0.01). The mRNA and protein levels of interleukin 6 (IL-6), IL-1β, and C-X-C motif chemokine ligand 8 (CXCL8) and the mRNA level of tumor necrosis factor-α (TNF-α) and chemokine C-C motif ligand 5 (CCL5) were significantly increased in LPS-induced GRECs (p<0.05 or p<0.01), while rutin supplementation significantly decreased the mRNA and protein levels of IL-6, TNF-α, and CXCL8 in LPS-induced GRECs (p<0.05 or p<0.01). The mRNA level of toll-like receptor 2 (TLR2), and the mRNA and protein levels of TLR4 and nuclear factor κB (NF-κB) was significantly improved in LPS-induced GRECs (p<0.05 or p<0.01), whereas rutin supplementation could significantly reduce the mRNA and protein levels of TLR4 (p<0.05 or p<0.01). In addition, rutin had a tendency of decreasing the protein levels of CXCL6, NF-κB, and inhibitor of nuclear factor kappa-B alpha (0.05< p<0.10). Rutin could significantly decreased interferon regulatory factor 3 mRNA expression in LPS-induced GRECs (p<0.05), whereas interferon induced protein with tetratricopeptide repeats 3 (IFIT3) and toll-interacting protein (TOLLIP) mRNA expression was not significantly different between the groups. LPS reduced the tight junction protein zonula occludin 1 (ZO-1) level in GRECs whereas rutin enhanced it. Rutin significantly improved tight junction protein Claudin-1 mRNA expression in LPS-induced GRECs (p<0.01), but could not affect tight junction protein Occludin mRNA expression.Conclusion: Rutin alleviated LPS-induced barrier damage in GRECs by improving oxidation resistance and anti-inflammatory activity, which may be related to TLR/NF-κB signaling pathway inhibition.

Although the local high quality chicken breed in China has excellent flavor, its growth rate is inferior to that of foreign breeds. To improve the growth rate of local chicken breeds, it is crucial to study the mechanism of chicken muscle development. Herein, Ningdu Yellow chicken was used as the research object, and a new hybrid breed (W) was obtained by crossing the G, H and D lines, which combined the excellent physiological characteristics of its parents. Combined analysis of Ningdu Yellow chickens and their parents was carried out. Chickens from 105-day-old lines (W, G, H) were selected, and breast meat and serum were extracted for transcriptome sequencing and metabolome determination to study their growth differences. The live weight, carcass weight, half-eviscerated weight, eviscerated weight, and breast muscle weight of W were significantly higher than those of G and H. Differential expression analysis identified 1700 differentially expressed genes (DEG), and gene ontology and kyoto encyclopedia of genes and genomes (KEGG) analyses identified 33 and 1 pathways related to growth and development and steroid biosynthesis, respectively. Next, pairwise analysis identified 57 KEGG pathways, among which the MAPK signaling, steroid hormone biosynthesis, tight junction, and PPAR signaling pathways were involved in growth and development. Cluster analysis found that genes highly expressed in the W group were associated with regulation of the actin cytoskeleton, riboflavin metabolism, steroid biosynthesis, and glycerophospholipid metabolism. The top 2 clusters obtained by protein-protein interaction analysis were important for the growth and development of chickens. Finally, the metabolomic analysis found key differentially accumulated metabolites (DAM) that might be account for the growth differences. Further integrated analysis identified key DEGs and DAMs that might be responsible for the observed growth differences. This study identified genes governing growth traits in Ningdu Yellow chickens, laying a theoretical foundation for the development of chicken breeding, the utilization of hybrid supporting lines, and promotion of the Chinese chicken industry.

Background: The testis, a critical reproductive organ in male animals, is responsible for sperm production and androgen secretion. Testis weight often correlates with reproductive performance, yet the genetic factors influencing testicular traits in chickens remain unclear. Methods: Previous genome-wide association studies (GWAS) have identified key genes affecting testicular traits in Kangle Yellow chickens, along with the associated regulatory pathways and Gene Ontology (GO) terms, through bioinformatic analyses. In this study, we utilized the existing literature, full-length transcriptome data, and proteome analyses to select key candidate genes. Results: We identified 13 associated markers for chicken testicular traits with 262 candidate genes. Nine candidate genes were found to regulate chicken testicular traits referred to integrated analysis, including CDH3, ZFPM1, CFAP52, ST6GAL1, IGF2BP2, SPG7, CDT1, NFAT5, and OPRK1. Physical interactions among these genes were also observed, implicating mechanisms such as cell adhesion molecules and neuroactive ligand–receptor interaction. Conclusions: These findings provide a genetic basis for improving testicular traits in Chinese native chicken breeds.