Toxic Effects Of Nanoparticle TiO₂Stress On Chara Vulgaris L.

With the rapid development of nanotechnology, the application field of nanometer materials is becoming more and more widespread, and at the same time, the biological safety problems of nanomaterials have attracted attention of worldwide scientists. Nanoparticle TiO2’s unique physical and chemical properties determine the characteristics of toxicology research. Nano TiO2can adopt all sorts of ways into the soil, air and water environment, finally enter the human body, so Nano TiO2’s safety evaluation and risk assessment have become the new topic of toxicology in the21’st century. This paper mainly studied the influence of Nano TiO2stress on Chara vulgaris L. in fresh water, from the morphology, physiological and biochemical indexes and molecular level, to assess the safety of nTiO2, and to provide theoretical basis for mechanism of nanometer materials inhibiting algae’s growth.Chara vulgaris L. was cultivated in two ways respectively, one in culture medium which filamentous green algae usually uses, and the other without any medium. Besides, try to simulate its natural habitat, we also used RS-188A multi-function submersible pump, and constant temperature stick. We found algae that not add nutrients grew better and faster instead, medium might change the solution’s pH value of the system, and it was more suitable for the growth of other kinds of alages, which competed with Chara vulgaris L.; Chara vulgaris L. was infected with different concentration of nTiO2for four days, the high concentrations group was damaged more seriously, Plastid dramatically reduced or necrosis in paraffin section under the microscope, and the integrity of the cells was destroyed.The experiment researched on the effects of nanoparticle titanium dioxide (nTiO2) suspensions to Chara vulgaris L. The contents of chlorophyll a,malonyldialdehyde (MDA), the activities of superoxide dismutase (SOD) and catalase (CAT) were measured in different concentration of nTiO2suspensions of0,0.01,0.1,1.0,10,100mg·L-1. The results indicated that, as the stress of nTiO2increased and time went, the contents of chlorophyll a, the activities of SOD and CAT showed a downward trend. By contrast, the MDA had an increasing trend. With the dose stress increasing, the differences were significant and the enzyme activity declined sharply compared with control. Taken together, the data suggested that the exposure of nTiO2had toxicity on C. vulgaris L. These affects had a dose dependent manner.Using random amplified polymorphic DNA (RAPD) technology to test the genomic DNA polymorphisms of Chara vulgaris L. on nTiO2stress. The results showed that algaes were exposed to different concentration of nTiO2for four days, of the16decamer oligonucleotide primers tested, only3gave specific and stable results, which were OPA-01, OPB-01and OPD-11.3primers gave a total of RAPD bands ranging from150to2000bp.The changes occurring in RAPD profiles of Chara vulgaris L. following nTiO2treatment included loss of normal bands and appearance of new bands and variation in band intensity in comparison to that of the control group. Additionally, the stability of genomic template decreased. These results indicated that genomic template stability (a qualitative measure reflecting changes in RAPD profiles) was significantly affected by the above nTiO2concentration. Thus, DNA polymorphisms detected by RAPD analysis could be used as a useful biomarker assay for the detection of genotoxic effects of nTiO2stress on Chara vulgaris L.