Dissertation > Excellent graduate degree dissertation topics show

The Interaction of Fluroxypyr with the Green Alga Chlamydonomas Reinhardtii

Author: ZhangShuang
Tutor: YangHong
School: Nanjing Agricultural College
Course: Applied Chemistry
Keywords: Fluroxypyr Chlamydomonas reinhardtii Toxic effects Reactive oxygen species Degradation Enrichment
CLC: S482.4
Type: Master's thesis
Year: 2010
Downloads: 5
Quote: 0
Read: Download Dissertation


Fluroxypyr [4-amino-3,5-dichloro-6-fluoro-2-pyridyloxyacetic acid] is a member of the pyridine class of herbicides. Fluroxypyr is an extremely effective post emergence herbicide that controls economically important broadleaf weeds and Alternanthera philoxeroides. Increasing usage of fluroxypyr results in higher risks from alternative products in regards to environmental burden. However, only a few reports have been published on the comparative toxicity of fluroxypyr toward the green algae and fewer reports are involved with biological responses of non target organisms induced by fluroxypyr. The introduction of fluroxypyr through runoff of rain and irrigation water into aquatic environments is likely to have adverse effects on non-target organisms such as algae. Algae are important components of the primary production, which are of initial importance in providing the energy that sustains fish and invertebrates in most aquatic ecosystems. Therefore, the action of herbicides on algae is not only important for the algae themselves, but also for the entire food web. In this study, C. reinhardtii was emploied as a test material because it is a powerful model system in bioassay experiments for investigating the toxicological responses of herbicides to eukaryotic organisms at the molecular level. The aim of the study is to elucidate the effects of excess fluroxypyr on the growth, physiological and biochemical responses of C.reinhardtii cells and to test the potential for C.reinhardtii to bioconcentrate fluroxypyr and trophically transfer the pesticide to invertebrate grazers.The effects of fluroxypyr on algae growth were investigated. Algae were cultivated with fluroxypyr at 0.05-1 mg L-1 for 2 days in dose-dependent experiments and incubated with 0.5 mg L-1 in time-denpendent experiments. Treatments with various levels of fluroxypyr induced only a slight but not significant increase in biomass as empressed by dry weight. The pattern of cell contents showed a typical’low-high-low’change. The contents of chlorophyll progressively increased with fluroxypyr concentrations at 0.05 and 0.25 mg L-1. However, further application of fluroxypyr up to 1 mg L-1 led to the significantly decreased contents A declined toxicity with the exposure time was also observed in this study. Our study revealed that chlorophyll content provided a sensitive and rapid system to determin the response of C.reinhardtii to fluroxypyr.The oxidative stress induced by fluroxypyr and the metabolic adaptation of C. reinhardtii were investigated. Production of reactive oxygen species (ROS) and DNA laddering as one of typical hallmarks of programmed cell death were observed in C.renhardtiiafter exposure to fluroxypyr. The levels of lipid peroxides, expressed as thiobarbituric acid reactive substances (TBARS), showed an increase, indicating oxidative damage to algae. To deal with oxidative damage, activities of antioxidant enzymes in C.reinhardtii substantially changed. Fluroxypyr induced the activities of APX, GST and EST at any level, whereas the activity of SOD was only stimulated at high levels. On the contrary to SOD, the activity of CAT showed a progressively increase at low fluroxypyr concentrations and a decraese at high fluroxypyr concentrations. Analysis of nondenaturing polyacrylamide gel electrophoresis (PAGE) confirmed these results.The bioaccumulation and removal capability of the freshgreen microalgae to fluroxypyr were studied. C.reinhardtii had the ability to accumulate and concentrate fluroxypyr and high removal capability at low fluxopyr concentrations. After 48 h exposure, accumulation of fluroxypyr in C.reinhardtii was greatly enhaced in cells with increases in initial fluroxypyr levels. The significantly larger BCFs were observed at observed at low levels of fluroxypyr. The BCF reached the peak level of 1173 after exposure to fluroxypyr at 0.25 mg L-1. The fluroxypyr biodegradation activity of C.reinhardtii evidently declined with further increases in initial fluroxypyr concentrations. Temporal varation of BCFs at 0.5 mg L-1 fluroxypyr by C.reinhardtii increased with exposure time and reached the maximum value of 271.01 on Day 4 and then declined. The biodegradation percentage of fluroxypyr at 0.5 mg L"1 increased with the expoure time.

Related Dissertations

  1. Study on the Degradation of Unsaturated Polyester Resin and Fiber Reinforced Polymer in Hot Compressed Water,TQ320.1
  2. Process Optimization and Degradation Kinetics for Microwave Vacuum Drying of Different Traditional Chinese Medicine Extract,TQ461
  3. Study on the Preparation of the Low Molecular Weight Fuciodan from Sargassum Henslowianum (C.Agardh) and Anti-tumor Activity,TS254.9
  4. Study on Activated Carbon Supported Cerium Catalytic Ozone Oxidation of Chloramphenicol,X703
  5. The Study of Preparation and Photocatalytic Activity of TiO2 by Electrospinning,O614.411
  6. The alkali fusion recovered from the glass fiber industry waste enrichment of platinum and rhodium metal,X781.5
  7. Process and Mechanism of Eucalyptus Pulp Bleaching Catalysed by Cu2+/Co2+,TS745
  8. The Research on Sulfate Leaching Properties of Cation-exchange Resin Used in Power Plants,TQ425.23
  9. Study of Nitrobenzene Wastewater’s Treatment by Combination of Immobile Phanerochaete Chrysosporium and Activated Sludge,X703
  10. Study on the Breeding of High Efficient Detoxification Strains and Suggestion Parameters of Solid Fermentation on Cottonseed Meal,S816.6
  11. The Effects of Overexpression of OsSsr1 on Stress Tolerance in Tobacco,S572
  12. Detection of Exogenous Recombinan DNA of Transgenic Rice and Its Rice Product,S511
  13. Study on Detection of Transgenic Ingredients in Genetically Modified Cottonseed Meal and Its Degradation during Feed Processing,S816
  14. Isolation and Characterization of Carbendazim-Degrading Strains, Cloning and Expression of the mheI Gene,X172
  15. Isolation, Identification and Degradation Characteristics of a Benazolin-Ethyl Degrading Bacteria and Degradation Pathway,X172
  16. Isolation and Identification of Pyrene-Degrading Strain SE12 and Its Degrading Effect,X172
  17. Isolation, Identification and Degrading Characteristic of a Cyhalofop-Butyl-Degrading Bacteria, and Cloning, Expression of a Cyhalofop-Butyl-Hydrolyzing Gene chbH,X172
  18. Resistance and Enrichment of Solanum Nigrum L. and Conyza Canadensis L,X173
  19. Functional Analysis of ACD5 during Infection of Botrytis Cinerea in Arabidopsis Thaliana,S432.1
  20. A Study on Environmental Behaviors of 2,4-D Butylate,TQ450.2

CLC: > Agricultural Sciences > Plant Protection > Pesticide ( chemical control ) > Various pesticides > Herbicides ( herbicide )
© 2012 www.DissertationTopic.Net  Mobile