Paternal contributions to embryogenesis extend beyond DNA, yet the molecular cargo carried by sperm and its impact on development remain poorly defined. Aggresomes (AGG), cytoplasmic inclusions formed by misfolded proteins, are present in mammalian gametes, but their functional consequences are unclear. Here, we show that excessive AGG content in bovine sperm head compromises preimplantation embryo development. Using image-based flow cytometry, sperm from 32 sires were classified into low-, moderate-, and high-AGG groups. AGG levels were unrelated to sire age and did not affect in vitro capacitation or acrosome remodeling. However, embryos derived from high-AGG sires exhibited reduced blastocyst formation, delayed cleavage timing, and a higher incidence of developmental arrest at the 4-6 cell stage. Embryos from high-AGG sires also accumulated more AGG during development, showed elevated reactive oxygen species (ROS) levels, and displayed altered mitophagy dynamics. Supplementation with an ER stress inhibitor temporarily improved cleavage but did not enhance overall blastocyst formation, indicating a limited and stage-specific effect. In vivo, embryos from high-AGG sires showed lower transferable quality compared with those from low-AGG sires. These findings establish sperm head AGG content as a novel paternal determinant of embryo quality. By linking sperm-borne misfolded protein aggregates to disrupted developmental pathways in the resulting embryo, our study reveals a previously unrecognized mechanism of paternal influence on fertility and suggests new opportunities for molecular screening for male fertility.
Anta, E., Sosa, F., Drum, J., Lockhart, K., McDonald, K., Fallon, L., Keller, E., Else-Keller, A., Kerns, K., Ortega, M. S.
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