Effects Of Some Heavy Metal Ions On Acute Toxicity Effect And Protective Enzyme Activity Of Oncomelania Hupensis

Objective:To explore the acute toxicity effects of copper(Cu²⁺),cadmium(Cd²⁺),mercury(Hg²⁺)and lead(Pb²⁺)to Oncomelania hupensis,and the dose-effect relationship between these four heavy metal ions and the activities of SOD,CAT,POD and other protective enzymes of O.hupensis.Methods:1?The O.hupensis used in the experiment were collected in the Yangtze River tributary river beach in Zhongming Town,Yi'an District,Tongling City.Five concentration gradients were set for each heavy metal,and 10 snails were placed in each group.After a certain period of time,the activities of the O.hupensis were observed,If the O.hupensis does not open operculum and does not crawl,the activity of the Oncomelania hupensis is considered to be inhibited.The number of inhibition of each group of O.hupensis was recorded at 24h,48h,72h,96h,and the EC50 was calculated.The number of O.hupensis deaths at 96h was recorded and the 96hLC50and safe concentration was calculated.2?The O.hupensis exposed for 24 hours were taken out,wash them three times with double distilled water,and put them into a negative eighty degrees Celsius refrigerator to freeze.Immediately after thawing at room temperature,the O.hupensis shell was quickly dissected and the soft tissue was collected.Absorb the surface moisture with absorbent paper,take the soft tissue of the seven O.hupensis,accurately weigh.In a ratio of 1:9,add 9 volumes of 0.86%NaCl solution.Grinding homogenate in ice water bath.Place the tissue homogenate in the centrifuge tube.Centrifuge for ten minutes at 2,500 rpm at zero degrees Celsius.Extracted the supernatant.Put it into EP tube for backup.The SOD,CAT,and POD activities were measured according to the kit instructions.Results:1?Acute toxicity of heavy metals to O.hupensis:?1?24h half effective concentration(24h EC₅₀)and 95%confidence interval?see brackets?:Cu²⁺?Cd²⁺?Hg²⁺?Pb²⁺are 0.74?0.61-0.98?,4.79?4.09-8.40?,1.90?1.48-4.85?,21.4?16.98-33.49?mg×L^-1,respectively.?2?The half effective concentrations at 48 h were 0.56?0.35-0.96?,3.52?2.40-7.79?,1.49?1.03-3.79?,and 9.98?6.82-12.80?mg×L^-1,respectively.?3?The half effective concentrations at 72 h were 0.46?0.29-0.63?mg.L-1,1.70?1.00-2.28?,0.83?0.02-1.62?,and 7.90?5.78-9.83?mg×L^-1,respectively.?4?The half effective concentration at 96h were 0.37?0.25-0.48?,1.26?0.67-1.70?,0.76?0.01-1.39?,and 5.42?1.28-8.15?mg×L^-1,respectively.?5?Cu²⁺?Cd²⁺?Hg²⁺?Pb²⁺96-hour median lethal concentration?96hLC50?and 95%confidence interval?see brackets?are:0.43?0.29-0.56?,2.96?1.87-5.51?,1.12?0.69-1.91?,12.22?8.89-15.35?mg×L^-1,respectively.The safe concentrations?SC?were:4.31,29.61,11.18,and 122.2?g×L^-1,respectively.The toxicity of Cu²⁺to O.hupensis is highly toxic;the toxicity of Cd²⁺and Hg²⁺to O.hupensis is moderately toxic;the toxicity of Pb²⁺to O.hupensis is low toxicity.2?Effects of different concentrations of heavy metal stress on the viability of O.hupensis protective enzymes:?1?SOD activity:rose to the highest value of 36.68 U/mgprot at Cu²⁺concentration of 2 mg×L^-1,and decreased to the lowest value at 16mg×L^-1 22.79 U/mgprot?P<0.05?;SOD activity increased to the highest value of 35.25U/mgprot when Cd²⁺concentration was 2 mg·L^-1,and decreased to the lowest value of25.37 U/mgprot at 8 mg·L^-1?P<0.05?;Hg²⁺concentration decreased to the lowest value of 22.13 U/mgprot at 0.025 mg×L^-1,increased to the highest value of 33.53 U/mgprot at 8 mg·L^-1,?P<0.05?;Pb²⁺concentration was at 5 mg·L^-1 rose to the first high value,dropped to the lowest value of 25.71 U/mgprot at 10 mg·L^-1,and increased to the highest value of 38.76 U/mgprot at 80 mg·L^-1?P<0.05?,.?2?CAT activity: decreased to a minimum of 11.78 U/mgprot at a Cu²⁺concentration of 0.5 mg·L^-1,and increased to a maximum of 26.14 U/mgprot at 4 mg·L^-1,and decreased at 16 mg·L^-1.To12.01 U/mgprot,?P<0.05?;the activity of Cd²⁺decreased to 14.48 U/mgprot at 0.25mg·L^-1,and increased to the highest value of 18.50 U/mgprot at 1,8 mg·L^-1.The enzyme activity value was the lowest at 8 mg·L^-1,which was 10.70 U/mgprot?P<0.05?.When the concentration of Hg²⁺was 0.025 mg·L^-1,the CAT activity decreased to the first low value and reached the highest at 0.1 mg·L^-1.The value was 17.76 U/mgprot,which decreased to a minimum of 8.75 U/mgprot at 0.8 mg·L^-1?P<0.05?.The concentration of Pb²⁺rose to the highest value of 22.27 U/mgprot at 5 mg·L^-1 at 80 mg·L^-1,the lowest value was 5.54 U/mgprot,?P<0.05?.?3?POD activity:reached the highest value of 6.75 U/mgprot when Cu²⁺concentration was 1 mg·L^-1,and reached the lowest value of 2.80 U/mg prot at 16 mg·L^-1?P<0.05?;Cd²⁺concentration was 0.25. When it was mg·L^-1,it dropped to the lowest value of 2.68 U/mgprot,and it increased to the highest value of 5.40 U/mgprot at 1 mg·L^-1,and decreased to 2.74 U/mg prot at 8mg·L^-1?P<0.05?;when the concentration of Hg²⁺was 0.05 mg·L^-1,the activity of POD decreased to the lowest value of 2.34 U/mgprot,and rose to the highest value of 5.16 U/mgprot at 0.2 mg·L^-1,and decreased at 0.8 mg·L^-1.To 2.75U/mgprot,?P<0.05?;Pb²⁺concentration increased to the highest value of 6.07 U/mgprot at 10 mg·L^-1,and decreased to the lowest value of 3.03 U/mg prot at 80 mg·L^-1,?P<0.05?.Conclusion:1?The toxicity of the four heavy metals Cu²⁺,Cd²⁺,Hg²⁺,and Pb²⁺to O.hupensis was in the order of Cu²⁺>Hg²⁺>Cd²⁺>Pb²⁺.The toxicity of Cu²⁺to O.hupensis is highly toxic;the toxicity of Cd²⁺and Hg²⁺to O.hupensis is moderately toxic;the toxicity of Pb²⁺to O.hupensis is low toxicity.2?Different concentrations of Cu²⁺,Cd²⁺,Hg²⁺and Pb²⁺had statistically significant effects on SOD,CAT and POD activity of O.hupensis.