Studies On Toxicological Effects Of Copper And Cadmium In Bellamya Purificata

1,An exposure experiment as K0rbor method was made to study the acute toxicity of 96 hours during exposure to Cu²⁺ and Cd²⁺ on Bellamya purificat.The results showed that LC₅₀ and true section of acute toxicity on Cu²⁺ was 0.382(0.314 -0.464) rag/L,while Cd²⁺ was3.390(2.819-4.076) mg/L.2,An exposure experiment was conducted to study the effects of copper(Cu²⁺) at different concentrations(Cu²⁺,0 mg/L,0.005 mg/L,0:01 mg/L,0.02 mg/L,0.05 mg/L) and different times from 0^th to 10^th days on concentrations of reactive oxygen species(ROS),from 0^th to 14^th days on antioxidant enzymes activities such as superoxide dismatase(SOD),catalase(CAT),glutathione S-transferase(GST) and concentrations of glutathione(GSH) and metallothionein(MT) and the extent of DNA single-strand breaking in liver and gill of Bellamya purificat.The results showed that Cu²⁺ had a time-dosage effect on concentrations of ROS,enzymes activities such as SOD,CAT,GST,and the concentrations of GSH and MT and the extent of DNA single-strand breaking.ROS tended to increase with a relatively significant time-dosage effect with the exposure time and dose increasing.The SOD,CAT and GST could be sharply induced in a short time of exposure,such as SOD in gills and livers was induced in four days, CAT induced in three days,and GST induced in four days after exposure.While with exposure time prolonging,the activities of SOD,CAT and GST were restraint.When the exposure time further increased to the14^th d,the activities of all enzymes in treatments with 0.005mg/L of Cu²⁺ fluctuated around the normal value,in treatments with 0.05 mg/L of Cu²⁺ were restrained,but induced with 0.01mg/L of Cu²⁺.The activities of enzymes in treatments with 0.02 mg/L of Cu²⁺ was induced in liver,but reversed in gill.Changes of GSH concentration in livers and gills were similar in inducement of a short time.GSH concentrations in livers were induced in five days after exposure,and that in gills were induced in four days after exposure.Moreover, the treatments with low dosage(0.005 mg/L) showed inducement phenomenon while high dosage(0.05 mg/L) showed restraint phenomenon.The MT(concentration of metallothionein) in livers and gills of B.purificata showed inducement in the whole process.Compared to the control group,the extent of DNA single-strand breaking in livers and gills of B.purificata was increased significantly.On the first day of exposure to Cu²⁺,the F value went down quickly and then up as DNA recovering to a certain degree,it reached to a higher point on the second day,later the extent of DNA single-strand breaking deepened,the F value tended to keep on dropping.On the 10th and 14(th) day,the F values in treatments with 0.005 mg/L,0.01 mg/L,0.02 mg/L and 0.05 mg/L showed no significant difference within groups in livers.3,An exposure experiment was conducted to study the effects of Cadmium(Cd²⁺) at different concentrations(Cd²⁺,0 mg/L,0.05 mg/L,0.10 mg/L,0.20 mg/L,0.50 mg/L) and different times(0-14d) on antioxidant enzymes activities such as SOD, CAT and GST and concentrations of GSH and MDA and the extent of DNA single-strand breaking in liver and gill of Bellamya purificat.The results showed that Cd²⁺ had effects on CAT,SOD,GST,GSH,MDA and the extent of DNA single-strand breaking with a significant time-dosage effect.The activity of SOD in livers was induced in the previous 10 days;the activity of SOD in gills in treatments of 0.05,0.10 and 0.20 has been induced all the time.CAT in livers in treatments with 0.05 and 0.10 had been induced in the first seven days after exposure,then the activity went down,and fluctuating around the level of the control group from the 10^th day to the 14^th day;the enzyme activity was increased significantly in treatments with 0.20 and 0.50 on the second day,later it kept decreasing until the 10^th day when restrainted extremely significantly.CAT in gills in all treatments had been induced for the first 7 days(except treatment with 0.50 on the 4^th day),and then the activity went down sharply,extremely significantly restraint from the 10^th day to the 14^th day.The activity of GST in treatments with 0.05 and 0.10 has been induced all the time,that in treatment with 0.20 was significantly or extremely significantly induced in the first 7 days while decreased after that,lower than that in the control group on the 14^th day;that in treatment with 0.50 was extremely markedly induced on the 1st while decreased after that.GST in gills changed in the similar way as that in the livers.All treatments were induced in the first 5 days while decreased after the 7^th day quickly,restraint from the 10^th day to the 14^th day.GSH in gills and livers in all treatments has been.significantly or extremely significantly induced for the first 7 days(except treatments in livers with 0.50 on 1st day and in gills on the 4^th day),on the 10^th day,it went down and then back as a result of upper to that in the control group on the 14^th day.The amount of MDA in the livers was reduced on the 1st day of exposure,and then it rose,the highest point was reached on the 4^th day.After that,the amount began to go down.The amount of MDA in the gills with treatments with 0.20 and 0.50 reached the top point,that with 0.05 and 0.10 was reduced after the top point on the 4^th day,fluctuation occurred,and no significant difference on the 14^th day between the treatments and the control group. The extent of DNA single-strand breaking in livers and gills of B.purificata increased after exposuring to different concentrations of Cd²⁺.Value of F in liver decreased in the first 4 days,DNA breaking of gills was severe on the first day of esposuring,then it increased again,which indicated that there was some recovering of the breaking DNA at first,and then more breaking appeared.F value decreased constently to the 14^th day.