On the Role of Seminal Fluid Protein and Nucleic Acid Content in the Paternal Epigenetic Inheritance

The evidence supports the occurrence of environmentally induced paternal epigenetic inheritance shaping the offspring phenotype in the absence of direct or indirect paternal care, and the empirical results clearly indicate that sperm epigenetics is one of the major actors mediating these paternal effects. However, sperm often make up only a small fraction of the male ejaculate in animals. Males also have a complex mixture of proteins, peptides, types of small RNAs, and cell-free DNA fragments in their seminal fluid. These molecules are in close contact with reproductive cells, tissues, organs, and other molecules of both males and females during reproduction. Moreover, their production and use are very sensitive to environmental conditions which makes them potential modulators of environmentally and developmentally induced paternal effects on the next generation(s). Although there is some intriguing evidence of seminal fluid-mediated paternal epigenetic effects, the underlying molecular mechanisms remain poorly defined. In this review, I discuss the current evidence regarding the association between seminal fluid and environmentally induced paternal effects, the possible trajectories, and the mechanisms in which seminal fluid can involve to mediate paternal epigenetic inheritance.