Effects of Scallop Mantle Toxin on the Male Mouse Reproductive System

The mantle of Yesso scallops contains a novel 18-/29-kDa protein toxin. Previous studies have confirmed that this toxin induces subacute toxicity without a clear dose-effect relationship. However, its effects on the male reproductive system remain unclear. This study aimed to explore the toxic effects of scallop mantle toxin (SMT) on the reproductive organs of male mice. Male Kunming mice were fed diets supplemented with 2% scallop mantle for 5 consecutive weeks, with the dosage determined based on previous studies from our research group. Instead of using purified toxin extracts, this study directly adopted raw scallop mantle tissue as the toxin source. Mouse growth status was monitored, with analyses performed on testicular and epididymal histology, sperm morphology, sperm DNA integrity, sperm nucleoprotein maturation, and the expression of spermatogenesis-related genes. The results showed that SMT induces significant reproductive toxicity in male mice by impairing spermatogenesis, as evidenced by structural disruption of seminiferous tubules, reduced spermatogenic cell layers, decreased counts of mature elongated spermatozoa, elevated sperm malformation and DNA damage, and disrupted histone-to-protamine transition. Furthermore, SMT significantly downregulated the expression of TSSK6, a postmeiotic differentiation marker, indicating that SMT primarily targets the late stages of spermatogenesis. Taken together, SMT damages the structural integrity of male reproductive organs and compromises sperm quantity and quality in mice, and may interfere with postmeiotic sperm formation and maturation. These findings provide an important theoretical basis for establishing scallop mantle-related reproductive toxicity models and evaluating shellfish food safety risks.