Transcriptome analysis of the uterovaginal junction containing sperm storage tubules in heat-stressed breeder hens

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إنجليزي. Sperm storage tubules (SSTs) in the uterovaginal junction (UVJ) of the oviduct are major sites of sperm storage after artificial insemination or mating. Female birds may regulate sperm motility in the UVJ. Heat stress can decrease the reproductive abil-ity of broiler breeder hens. However, its effects on UVJ remain unclear. Changes in gene expression aid in under-standing heat stress-affected molecular mechanisms. Herein, we wanted to conduct a comparative transcrip-tomic analysis to identify the differentially expressed genes (DEGs) in the UVJ of breeder hens under ther-moneutral (23 & DEG;C) and heat stress (36 & DEG;C for 6 h) condi-tions. The results indicated that cloacal temperatures and respiratory rates were significantly increased in heat-stressed breeder hens (P < 0.05). Total RNA was extracted from the hen UVJ tissues containing SSTs after heat exposure. Transcriptome analysis identified 561 DEGs, including 181 upregulated DEGs containing heat shock protein (HSP) transcripts and 380 downre-gulated DEGs containing immune-related genes, such as interleukin 4-induced 1, radical S-adenosyl methionine domain containing 2, and 2'-5'-oligoadenylate synthe-tase like, in heat-stressed hens. Gene Ontology analysis revealed the significantly enriched terms involving HSPs. Kyoto Encyclopedia of Genes and Genomes anal-ysis identified 9 significant pathways, including the pro-tein processing in endoplasmic reticulum (11 genes including HSPs), neuroactive ligand-receptor interac-tion (13 genes including luteinizing hormone/choriogo-nadotropin receptor), biosynthesis of amino acids (4 genes including tyrosine aminotransferase), ferroptosis (3 genes including heme oxygenase 1), and nitrogen metabolism (carbonic anhydrase [CA] -12 and CA6) pathways. Protein-protein interaction network analysis of DEGs revealed 2 large networks, one containing upre-gulated HSPs and the other containing downregulated interferon-stimulating genes. Overall, heat stress inhib-its innate immunity in the UVJ tissues of broiler chick-ens, and heat-stressed chickens protect their cells by increasing the expression levels of HSPs. The identified genes are potential candidates for further exploration of the UVJ in heat-stressed hens. The identified molecular pathways and networks increase our understanding of the sperm storage reservoirs (UVJ containing SSTs) within the reproductive tract and may be used to pre-vent heat stress-induced fertility loss in breeder hens.