biostudies-literatureThelie AAgence Nationale de la RechercheInstitut National de la Recherche AgronomiqueH2020 European Institute of Innovation and Technology762-775https://www.ebi.ac.uk/biostudies/studies/S-EPMC6767445biostudies-literatureUnknown86(7)The seminal plasma is a very complex fluid, which surrounds sperm in semen. It contains numerous proteins including proteases and protease inhibitors that regulate proteolytic processes associated with protein activation and degradation. We previously identified a seminal protein, chicken liver trypsin inhibitor 1 (ClTI-1) over expressed in semen of roosters with high fertility, suggesting a role in male fertility. In the present study, we showed that ClTI-1 gene is actually SPINK2. Using normal healthy adult roosters, we showed that SPINK2 amount in seminal plasma was positively correlated with male fertility in chicken lines with highly contrasted genetic backgrounds (broiler and layer lines). Using affinity chromatography combined to mass spectrometry analysis and kinetic assays, we demMolecular reproduction and developmentThe seminal acrosin-inhibitor ClTI1/SPINK2 is a fertility-associated marker in the chicken.PMC6767445ANR‐11‐INBS‐0003Nº677353Govoroun MRehault-Godbert SFouchecourt SPoirier JCBlesbois EThelie AfalseThe seminal acrosin-inhibitor ClTI1/SPINK2 is a fertility-associated marker in the chicken.The seminal plasma is a very complex fluid, which surrounds sperm in semen. It contains numerous proteins including proteases and protease inhibitors that regulate proteolytic processes associated with protein activation and degradation. We previously identified a seminal protein, chicken liver trypsin inhibitor 1 (ClTI-1) over expressed in semen of roosters with high fertility, suggesting a role in male fertility. In the present study, we showed that ClTI-1 gene is actually SPINK2. Using normal healthy adult roosters, we showed that SPINK2 amount in seminal plasma was positively correlated with male fertility in chicken lines with highly contrasted genetic backgrounds (broiler and layer lines). Using affinity chromatography combined to mass spectrometry analysis and kinetic assays, we dem2019-01-01T00:00:00Z2019 Jul2025-04-18T17:12:07.432Z2019-10-11T07:13:15ZS-EPMC67674453103305510.1002/mrd.23153