The herbicide 2,4-dichlorophenoxyacetic acid induces the generation of free-radicals and associated oxidative stress responses in yeast.
The pro-oxidant action of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is demonstrated in this study using Saccharomyces cerevisiae as a eukaryotic experimental model. Evidence is presented for the generation of hydroxyl-radicals, in yeast cells suddenly exposed to 2,4-D, detected by in vivo electron paramagnetic resonance (EPR) spectroscopy using 5,5'-dimethyl-1-pyrroline N-oxide and 5-tert-butoxycarbonyl-5-methyl-1-pyrroline N-oxide as spin-traps. The intensity of the EPR spectra was dependent on the concentration of herbicide tested and was consistently higher in a mutant (Deltasod1) devoid of the cytosolic CuZn-superoxide dismutase. A time-course-dependent variation of the level of free-radical adducts was registered upon sudden exposure of an yeast cell population to concentrations of 2,4-D that lead to an initial period of viability loss, before resumption of inhibited growth by the viable adapted population. The variation pattern of the level of hydroxyl-radical adducts correlated with the one determined for the activity of Sod1p, cytosolic catalase Ctt1p, and the dithiol glutaredoxins Grx1p and Grx2p.
Biological Sciences Research Group, Centro de Engenharia Biológica e Quimica, Instituto Superior Técnico, 1049-001 Lisbon, Portugal.
Miguel C
MC
Teixeira
João P
JP
Telo
Nuno F
NF
Duarte
Isabel
I
Sá-Correia
D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology*; D002374:Catalase / Q000737:chemistry / Q000378:metabolism; D002474:Cell-Free System; D004305:Dose-Response Relationship, Drug; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D054477:Glutaredoxins; D005978:Glutathione / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006540:Herbicides / Q000494:pharmacology*; D009154:Mutation; D016877:Oxidants / Q000737:chemistry; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry; D019097:Spin Trapping / Q000379:methods; D013482:Superoxide Dismutase / Q000737:chemistry; D013997:Time Factors
D005609:Free Radicals; D054477:Glutaredoxins; D006540:Herbicides; D016877:Oxidants; D029701:Saccharomyces cerevisiae Proteins; D015084:2,4-Dichlorophenoxyacetic Acid; D010088:Oxidoreductases; D002374:Catalase; D013482:Superoxide Dismutase; D005982:Glutathione Transferase; D005978:Glutathione