Toxic Effects Of Nonylphenol On Paphia Undulate And Ruditapes Philippinarumon

Nonylphenol was a representative environmental estrogen in alkylphenol compounds,as a certain environmental endocrine disruptors. It was widely used in industrialproduction, and released into the environment with domestic and industrial sewage, itcan effect on aquatic organisms and human body by bioconcentration with humanhealth hazards finally. Environmental hormone pollution problems have became one ofthe hot issues in international environmental science with the environmental hormoneswere widely used worldwide.This paper studied the trends of the antioxidant defense system（SOD、CAT、POD、GSH、 GST、MDA） and gene expression（Cu/Zn-SOD、GST-pi、 VpGPx、CYP、RpAhR）between Paphia undulata and Ruditapes philippinarum after stressing by NP and cleanwater releasing. This paper also studied the biological toxic effects and the recoverystatus by observing the histopathological damage between mantle and gill in P. undulataand R. philippinarum after NP stressed. The main research contents as followed:1. Toxicological Effects of NP on the antioxidant system visceral mass of P.undulateThe96h median lethal concentration (96h LC₅₀) of NP on P. undulate was0.26mg· L^-1, using1/10of the96h LC₅₀as the highest long-term exposure of toxicconcentrations, there were three NP chronic exposure groups: low(1μg·L^-1),middle(10μg· L^-1),high(25μg· L^-1), and a blank control group.At the beginning, the SOD activity of P. undulata visceral mass was inhibited verysignificantly （P<0.01） in the low and middle groups, and POD activity was also inducedvery significantly（P<0.01）, which seems to be a typical "Toxicity of excitotoxic effect".During the stress period, the SOD activity and GSH content in the visceral mass of P.undulate had an initial decrease and followed by a gradual increase exposed to the lowand middle concentrations of NP, while the POD activity and MDA content wereincreased firstly then declined; The SOD activity had a trend of inhibited firstly andthen induced, POD activity and MDA content were declined firstly, then increased andat last declined again. At the same time, GSH content had always been significanthigher than control group. Various indicators gradually returned to the level of thecontrol groups in the low and middle groups after removing stress, but there were alsohad significant differences between high groups and control group. The SOD activity of R. Philippinarum mantle was slightly inhibited just in lowconcentration at1d under the stress of NP, followed by a trend of induced firstly andthen inhibited totally; POD activity was inhibited in low and middle groups at15dduring the stress period, the other groups at different time expressed induced state; GSHcontent was lower than control group at1d and7d, while it significant higher thancontrol group in all groups at15d; the MDA content had no change at1d, GSH contentin low groups was lower than control group only happened at7d, and in middle groupsit was lower than control group at3d then always higher at the later; while in the highgroups GSH content was higher than control group at3d and7d. All the indicatorsbecame normal in low groups after the end of release; while the other indicators degreeof recovery were not ideal in middle and high groups, except the content of GSH.2. Toxicological Effects of NP on the antioxidant system in visceral mass of R.philippinarumThe96hLC₅₀of NP on R. philippinarum was0.469mg· L^-1. There were four NPchronic exposure groups: A (1.6μg· L^-1), B (5.04μg· L^-1), C (15.88μg· L^-1), D (50μg· L^-1), and a blank control group.During the stress period, SOD activity of R. philippinarum visceral mass wasinduced firstly and then inhibited at last increased.at the time of15days,the SODactivity had a slightly raise only in in D group.The dose effect trends of CAT activityand POD activity was not obvious, they were induced at15d. GST activity was inducedfirstly and then inhibited, and it was inhibited very significantly （P<0.01） at15d; GSHcontent was declined firstly and then increased, it was significant lower than controlgroup （P<0.01） in D group at15d, it showed that NP was accumulated in the other threegroups. The change of MDA content was not obvious at pre-dose effect, it becameobvious after7d, and significant higher than control group （P<0.01）. During the timeof NP released all the indicators of the three groups had not become normal level exceptthe POD activity in A group after15d.3.The effect of gene expression on five kinds of mRNA exposed to NP invisceral mass of R. philippinarumThe relative expression level of gene about Cu/Zn-SOD、GST-pi、VpGPx、CYP andRpAhR in visceral mass of R. philippinarum had significant changes in four different concentrations:A(1.6μg· L^-1),B(5.04μg· L^-1),C(15.88μg· L^-1) and D(50μg· L^-1)under NP stress.During the stress period, the expression of Cu/Zn-SOD inhibited firstly theninduced, and inhibited at last.the inhibitory rate was defferent among the four groups,the rate of15d was significant lower than it showed at7d. the expression of GST-pi,VpGPx and AhR were increased and then decreased, their relative expression level weresignificant lower than control group at15d, the reducing degree of AhR was biggest.The relative expression level of CYP dose-response was not obvious,their relativeexpression level were significant lower than control group （P<0.01） at15d.Thoughindividual groups relative gene expression levels became a little higher after stress,relative expression levels of five gene were significant lower than control group.4Microscopic observations of mantle and gill structures exposed to NP in R.philippinarumThere were pathological damage under different concentration of NP stress inmantle and gill about R. Philippinarum, during the exposed concentrations becominghigher, the damage of mantle and gill structures became more serious.The mantleappeared cell deformability, nucleus coloration increased, organization vacuolesbetween muscle fiber aggregation after long time contamination.There were somephenomenon such as significant swelling, merging, curl deformation, necrosis on gilllamellae.