The White Leghorn chicken is a renowned high-yielding egg-laying breed, frequently utilized in hybrid breeding programs for the modification of egg production traits. However, the plumage color genes carried by White Leghorns, particularly the sex-linked barring feather gene, have rarely been exploited in breeding practices. Progeny resulting from crosses with White Leghorns predominantly exhibit white plumage due to the dominant white feather gene, which epistatically masks other feather colors. In this study, White Leghorns were reciprocally crossed with Dongxiang Black-Feathered Blue-Shelled Egg Chickens (DBBC), and the F1 generation exhibited white plumage in all individuals. In the F2 generation, feather color segregated into black, mottled, and barred patterns. Analysis revealed that the segregation of the barred plumage pattern followed a Z-linked inheritance model. In previously reported polymorphisms in the CDKN2A gene associated with barred feather patterns, we identified that only SNP4 was applicable for barring gene identification in this population. We also analyzed the correlation between the barring gene genotype and the color depth phenotype of barred feathers in adult roosters. The accuracy of identifying non-deeply barred roosters as homozygous for barring gene was 98.2 %. Population testing confirmed that the barring gene originated from the White Leghorn population. When barred hens derived from White Leghorns were crossed with black-feathered roosters, the accuracy of sex identification based on the barred feather phenotype in chicks was only 89.98 %. Two primary factors contributed to the reduced accuracy. First, two types of mottled feather phenotypes displayed epistatic effects over the barred phenotype, masking it in chicks. By excluding mottled chicks, the accuracy of sex identification increased to 93.99 %. Second, the barred feather pattern inherited from White Leghorns showed considerable variation in chicks, making identification difficult. By adopting the criterion of identifying the brightest white spot located along the midline of the chick's head, the accuracy of sex identification could be further improved. This study demonstrates that the sex-linked barring feather gene can be isolated from White Leghorn chickens and utilized for sex identification at hatch. In addition, White Leghorn chickens carry a wealth of other feather color genes that are masked by the dominant epistatic white feather gene. Crossing White Leghorn chickens with colored-feathered chickens can result in the segregation of novel feather colors, offering promising prospects for breeding applications.

Background tRNA fragments (tRFs) are small non-coding RNAs generated from cleaved tRNA molecules, playing key roles in gene regulation and cellular processes. Produced by ribonucleases like angiogenin and Dicer, tRFs vary in length and function in gene silencing and stress responses. They interact with Argonaute proteins and affect mRNA levels, and are emerging as potential diagnostic and therapeutic targets for diseases such as cancer and neurodegenerative disorders. Given that the skin is the largest organ in mammals, it serves as an ideal model for studying development and various diseases. Therefore, this study investigates tRF expression in sheep skin tissues to understand their regulatory roles during growth and development.

Results This study analyzed skin tissue from five 1-month-old lambs and five 24-month-old adult Tan sheep using small RNA sequencing and proteomics. Raw sequencing data were filtered and aligned to identify various tsRNAs, while proteomic data were assessed for differential expression. Principal Component Analysis (PCA) revealed distinct separation between juvenile and adult samples based on tsRNA expression patterns, indicating intra-group similarity and inter-group differences. Differentially expressed tsRNAs were identified, with 19 highly expressed tsRNAs at 1 month of age. Proteomic screening identified 932 highly expressed and 835 lowly expressed proteins in the 1-month-old group, with functional enrichment highlighting immunity and inflammation pathways. Predictive analysis of tsRNA target genes intersected with 20 differentially expressed proteins involved in mitochondrial metabolism and stress response.

Conclusion This study reveals that tsRNAs significantly influence developmental and immune processes in sheep, with distinct expression patterns between juveniles and adults. Future research should validate these findings and fur ther elucidate the functional mechanisms of tsRNA regulation.

The current study aimed to detect the genetic variability of mitochondrial DNA (mtDNA) cytochrome B (CYTB) gene in 80 native Egyptian rabbits (NER) belonging to three populations in three different agriculture regions (Delta, Middle, and Upper Egypt) and also investigate the origin of these breeds by phylogenetic relationship analysis. A total of 62 haplotypes were recorded among the three NER populations. The native Upper Egypt rabbits (NUER) expressed the highest number of haplotypes, mutations, polymorphic sites, and haplotype diversity (23, 55, 51, and 1.00, respectively). While it gave the lowest values of nucleotide diversity (0.0262) and Tajima's D (−0.01435), the percentage of mutual haplotypes was 4.8 % between the Middle and Delta Egypt populations. The phylogenetic analysis showed that there were more separated haplotypes of NUER compared to other populations. The same finding was also observed when supported by 31 sequences of different rabbit breeds retrieved from the GeneBank database. A mutual haplotype was observed between native Delta Egyptian rabbits (NDER) and New Zealand (NWZ) rabbits. The results of this study shed light on the importance of indigenous breeds in rural areas through mtDNA, which contributes to finding sustainable strategies to conserve and improve genetic resources in Egyptian rural areas