Effect of 4-nonylphenol on the sperm dynamic parameters, morphology and fertilization rate of Bufo raddei
4-Nonylphenol (NP) is a compound that causes endocrine disruption and affects sperm quality of mammals and fish. However, the effects of NP on the sperm and fertilization rate of amphibians remain unknown. This study investigates the in vivo and in vitro effects of NP on the sperm dynamic parameters and fertilization rate of Bufo raddei during the period of amplexus and fertilization, and proposes the induction of these effects. In in vivo assay, male B. raddei were exposed to 3 concentrations of NP (50, 200, or 400 μg/l) or alcohol (0.04‰, control) for 1-3 days. The results suggested that effects on NP on the sperm dynamic parameters, sperm integrity and fertilization rate were not significant (p>0.05). In in vitro assay, the sperm of B. raddei was directly exposed to NP. Based on the results, NP significantly affected the sperm dynamic parameters and integrity (p<0.05). Meanwhile, the sperm reactive oxygen species (ROS) level in the sperm increased significantly (p<0.05), and a negative correlation was recorded between sperm motility and its corresponding ROS level (R=−0.90). Besides, fertilization rate was significantly reduced compared with that of control (p<0.01). The sperm membrane was impaired as well. However, a risk that NP can disrupt the reproduction behavior of B. raddei exists, and the ROS induced by NP and NP itself would be associated with the reduction of fertilization.
Keywords: 4-Nonylphenol, Bufo raddei, sperm, morphology, fertilization