| The toxic effect of Hg2+, Pb2+, Cd2+ on the Calanus sinicus total superoxide dismutase (T-SOD) and the impact of heavy metals to mitochondrial COI gene of Calanus sinicus were studied in this paper.The acute toxic effects of Hg2+, Pb2+, Cd2+ on Calanus sinicus was studied in the first part. After the pre-test to determine Calanus sinicus best acclimation in the laboratory, three kinds of heavy metals on Calanus sinicus in the 96h acute toxicity test was carried out. Three kinds of heavy metals on Calanus sinicus acute toxicity were obtained from strong to weak with the order of Hg2+> Cd2+> Pb2+. The 96 h-LC50 of Hg2+ on Calanus sinicus was 0.0106mg/L, the 96 h-LC50 of Cd2+ on Calanus sinicus was 0.0551mg/L and the 96 h-LC50 of Cd2+ was 3.7439 mg/L.Effects of three heavy metal ions(Hg2+, Pb2+ and Cd2+)on the total superoxide dismutase (T-SOD) activity of the tissue of Calanus sinicus were determined through sublethal toxicity experimentation in the second part. The results showed that the SOD activity changed markedly with prolonged exposure of these ions. When the concentration of Hg2+ were 0.0013mg/L-0.0053mg/L, the T-SOD activity reaching the maximum at 12 hours. When the concentration of Pb2+ were 0.4680mg/L,0.9360mg/L and 1.8720mg/L, the T-SOD activity reached the maximum at 36 hours,24 hours and 12 hours, respectively. Effects of Hg2+ and Pb2+ on the SOD activity were increased first and then decreased during prolonging the exposure time. However, effects of Cd2+ on the SOD activities were increased first and then decreased, then decreased after increased. In all concentrations of Cd2+, the T-SOD activity reached the maximum at 12 hours.Preliminary study of Hg2+ on the mitochondrial COI gene of Calanus sinicus was carried out in the third part. Through the control group and experimental group, DNA extraction of Calanus sinicus, fragment of PCR amplification, cloning and determination of gene sequences, with different concentrations of Hg2+ on the base composition of Calanus sinicus mtCOI effects were compared.The results showed that, 10μg/L Hg2+ treated Calanus sinicus mtCOI gene nucleotide sequence has 99% of sequence similarity compared with GenBank accession no. AF332093, five variation points were found in the 33,36,212,365 and 368 points, and the mutation type of 33 is transversion while others are conversion.20μg/L Hg2+ treated Calanus sinicus mtCOI gene nucleotide sequence has 98% of sequence similarity compared with GenBank accession no. AF332093, six variation points were found in the 34,50,64,365,368 and 705 points. The mutation type contains conversion(34,365,368), deletion(50,64) and insertion(705).40μg/L Hg2+ treated Calanus sinicus mtCOI gene nucleotide sequence has 98% of sequence similarity compared with GenBank accession no. AF332093, eight variation points were found in the 33,35,41,365,368,660,663 and 670 points, and the mutation type contains transversion (41,663,670), conversion (365,368,660), insertion(35) and deletion(33).By the experimental results, the Calanus sinicus toxicity of heavy metal ions is very sensitive. Low concentration can cause large changes in T-SOD, which makes SOD activity of changes to water pollution monitoring indicators possible. Heavy metal ions lead to Calanus sinicus mtCOI gene mutations:Hg2+with the concentration of 20μg/L has more significant effect on the mtCOI gene base sequence of Calanus sinicus than that of Hg2+with the concentration of 40μg/L, Hg2+ with the concentration of 10μg/L has the least significant effect in the three concentrations. However, mutations in the gene and its encoded amino acid and protein expression to be further studied. |
PDF Full Text Request