FIG. 1.

Thin sections of midpieces of boar spermatozoa exposed to extracts of S. griseus 8/ppi (A through C), extracts of S. griseus DSM 40236^T (D), and commercial valinomycin (E) for 7 days. (A) Midpiece of a spermatozoon with mitochondrial damage. The frequency of swollen mitochondria in the spermatozoan midpiece was >60% after exposure to 20 μg (dry weight) of strain 8/ppi crude extract per ml. After exposure to 2 μg ml⁻¹ the frequency of swollen mitochondria was <20% (data not shown). (B) Thin section of the midpiece of a boar spermatozoon exposed to a toxic strain 8/ppi HPLC fraction, showing swollen mitochondria with disrupted outer membranes. (C) Midpiece of a spermatozoon exposed to a nontoxic strain 8/ppi HPLC fraction. (D) Section of a midpiece exposed to a similarly prepared S. griseus DSM 40236^T extract (20 μg [dry weight] per ml of extended boar semen). (E) Midpiece after exposure to 200 ng of commercial valinomycin ml⁻¹. Bars = 200 nm.