The Effect Of Environmental Factors On Microcystin Synthetase Gene Expression Levels And Aquatic Plants Of Resistive Mechanism To Microcystins

Microcystis aeruginosa PCC 7806 total RNA RT- PCR product was subcloned into PGEM-T vector to cont rust recombinant plasmid. Developped standard curve s of 16srRNA,mcyH and mcyB by different folds serial diluted dplasmids DNA,and r~2 of three standard curves separately was 0.9916,0.9938 and 0.9939 by the method, The plasmid standard has a better reproducibility. It can satisfy the need experiments.Making use of the three standard curve,the experiment adopted real-time RT-PCR and ELISA methods to research mcy genes transcriptional lever and the MC content of M. aeruginosa PCC7806 under different temperature,light and concerntrations of 2ip.The result showed : the transcriptional lever of mcyH and mcyB presented increased trend as the light intensity increased,and the gene transcriptional lever and the MC content had no significant difference,however 2ip could inhibit the MC content and gene transcriptional lever,as a whole, the gene transcriptional lever and the MC content had no correlation.The research on the effects of microcystins on aquatic plants has increased. Some aquatic plants have some tolerance to microcystins but the mechanism of the tolerance is still unknown. In this experiment, we used microcystins of different concentrations to study the toxic effect in Lemna minor and Myriophyllum spicatum. Experiments were carried out with a range of microcysitns levels (equivalent to 0, 0.1, 0.5, 1.0, and 4.3mg/L). The growth of L. minor (as fresh weight) and chlorophyll a content were significantly reduced and Superoxide dismutase (SOD) activity was significantly decreased at microcystins concentration up to 0.5mg/L. The growth of M. spicatum was affected only weakly by microcystins and 0.5 mg/L treatment caused significant decrease in chlorophyll a content. Besides, the SOD activity of M. spicatum positively correlated to microcystins concentration (P<0.01). The result indicated that M. spicatum was more tolerant to microcystins than L. minor and the induced SOD activity may contribute to the tolerance. The experiment also indicated that catalase (CAT) activity was not significantly influenced by microcystin for both the two tested aquatic plants.