Dynamics of ESR2 and PTHLH gene expression during post-embryonic development of the reproductive system in hens

The transition from classical to genomic selection is of strategic importance for the poultry industry of the Russian Federation. Genes involved in the regulation of the reproductive system are of particular significance for productivity. The aim of the study was to analyze the dynamics of the expression levels of the ESR2 and PTHLH genes in the ovarian tissues of hens of the SM9 original line of the «Smena 9» cross at key stages of post-embryonic development. The research material consisted of ovarian tissues collected from birds of various age groups. The evaluation of the relative gene expression level was performed in the ovarian tissues of birds from four age groups using quantitative real-time PCR with the ΔCt method. The expression of the ESR2 gene in the ovary varied significantly. The maximum activity level was recorded during the phases of postnatal adaptation (week 2) and ovarian activation (week 10). With the onset of puberty, the expression steadily decreased, reaching a minimum by the active egg-laying phase at week 27. The dynamics of PTHLH were more gradual: stable expression in the early periods of development was followed by a significant decrease in activity exclusively during the active egg-laying stage. The regulation of ESR2 and PTHLH gene expression is stage-specific. High gene activity in the early stages ensures follicle morphogenesis. The subsequent decrease in transcription is physiologically associated with the onset of egg-laying. It is advisable to use the identified genes affecting the development of the reproductive system in hens as candidates for the study of single nucleotide polymorphisms within the framework of marker-assisted selection.

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