Effects Of Nonylphenol On Amplexus, Sperm And The Early Development Of Male Bufo Raddei

Nonylphenol (NP) is the final degradation product of alkylphenol poly ethoxylates (APE), which is a kind of nonionic surfactant widely used in industry, agriculture and other production activities. And, NP is usually present in aquatic environments. Owning to its estrogen effect and high resistance to biodegradation, NP has attracted great attention of researchers. However, as an environmental estrogen widely distributed in water in Lanzhou region, little is known about the effect of NP on the amplexus of amphibia, especially on its sperm and its early development.The present study mainly investigeted the effects of NP with environmental-relevant concentrations in Lanzhou region on amplexus, sperm and early development of male Bufo raddei. Such information would be valuable for better estimating the risks of NP in relation to the decline of B. raddei around Lanzhou region.1. The acute toxicity of the NP on the embryo of B. raddei and the distribution of NP in the body of male B. raddei was detected. It was found that:(1) 24 h LC50 of NP of B. raddei was increased gradually during the development of embryo. The 24h LC50 of NP of 22 developing stage to 39 developing stage were 0.18 mg/L to 0.62 mg/L. (2) NP could enter the testes of B. raddei through the blood-testis barrier and the blood-brain barrier. NP could affect the testis tissue directly. (3) The level of NP increased in liver, but decreased in blood, testes and the brain in male B. raddei exposed to NP for 48 h. (4) The mainly tissue of the metabolism of NP in B. raddei was liver.2. The effects of NP on the amplexus and the hormone of male B. raddei were investigated. The study showed that:(1) NP (≥200μg/L) disturbed the amplexus of male B. raddei, the number of the divorced toad and the death of male B. raddei increased. (2) The level of FSH and LH reduced significantly in male B. raddei exposed to NP (≥200μg/L) for 3 days. And the level of testosterone increased in the blood in male B. raddei exposed to NP (≥50μg/L) for 9 days, but the difference was not significant compared to control. Hence we presume that NP (≥200μg/L) disturbed the amplexus of B. raddei by reducing the level of FSH and LH of male B. raddei.3. The effects of NP on the sperm of B. raddei during the amplexus and fertilization. The study showed that:(1) NP (≤400μg/L) had no significant effects on the integrity rate or the dynamic parameters of sperm of B. raddei during amplexus. (2) NP (≥200μg/L) significantly reduced the sperm motility and the fertilization rate during fertilization. (3) ROS level significantly increased in the sperm directly exposed to NP (≥50μg/L). And the ROS level had high-negative correlation with the concentration of NP.4. The effects of NP on the ultra structure of sperm. Results showed that:(1) Present study enriched the data about the ultra structure of the sperm of B. raddei. The sperm of B. raddei was about 58.60μm long, the length of the head and tail of sperm were about 20.47μm and 39.52μm respectively. Sperm was consisted of three parts: a head, a midpiece and a tail. (2) NP (≥200μg/L) seriously impaired the membrane of sperm's head, midpiece and flagellum. The membrane was broken from the head near the midpiece, and the mitochondria were impaired too. The impairment of the structure would lead to the lower sperm motility.5. The effects of embryo jelly coat to reduce the absorption of pollutants. The results showed that:(1) The 32.20% absorption of Cd2+ and 59.03% absorption of NP of intact embryo were reduced compared to that of dejelly embryo exposed to 1 mg/L Cd2+ or 1 mg/L NP for 40 h. (2) The jelly coat of embryo showed more resistance to NP than the Cd2+. (3) The jelly coat of embryo could reduce and prevent the adverse effects of pollutants on the hatching by reducing the absorbtion.6. The effects of NP on the morphological development of the embryo. (1) NP (≥200μg/L) blocked the embryo development from the embryonic rotation period. (2) NP (≥200μg/L) would reduce the length of embryo. (3) The decline of SOD and the increase of MDA induced by NP of tadpoles did not return to normal levels within 14 days.Base on these findings, short-term exposure of B. raddei to NP during amplexus or fertilization in Lanzhou region would not have significant effects on its amplexus, sperm quality, fertilization rate and its early development.