Aquaporins 1, 2, 4, and 9 in gander testes throughout the annual period

Many efforts have been made to study the role of aquaporins (AQPs) in livestock reproduction, but little data are available on poultry. The aim of the study was to investigate the mRNA transcript levels, protein abundance, and immunofluorescent localization of water-transporting AQP1, AQP2, AQP4, and aquaglyceroporin AQP9 in the gander testes throughout the annual breeding stages. Testes from ganders (n = 25) were obtained at five stages, i.e., prebreeding (PrB), peak of reproduction (PR), postbreeding (PoB), nonbreeding (NB), and onset of reproduction (OR). The gene and protein expressions of AQPs were examined by quantitative real-time PCR and Western blotting, respectively. Stage-dependent changes in the mRNA abundance of all AQPs were observed. The level of AQP1 mRNA was higher at the PrB than at the PR, PoB, and NB stages. In contrast, the level of AQP4 transcript was lower at the PrB, PR, and OR stages than at the PoB and NB stages. Relative expression of AQP2 and AQP9 had the same pattern of changes, i.e., the levels were lower at the PrB, NB, and OR stages compared to the PR and PoB stages. Immunofluorescence showed a positive reaction for all AQP proteins in somatic and germ cells of the testes throughout the annual breeding stages, with stage-related differences in their localization patterns. The diverse mRNA expression patterns and changes in the localization of AQP proteins across the annual period suggest their involvement in processes related to development, regression, and recrudescence of the testes.