Transcriptional expression levels and biochemical markers of oxidative stress in the earthworm Eisenia andrei after exposure to 2,4-dichlorophenoxyacetic acid (2,4-D)

• We studied the effects of 2,4D on oxidative stress parameters in earthworms.
• 2,4D exerted a negative effect on worm’s growth as well as on LMS.
• A positive gene expression regulation of oxidative stress related target was observed Our data should be considered in view of the effects of pesticides in non target organisms.

This study investigated the stress response of earthworms (Eisenia andrei) to exposure to a commonly used herbicide, 2,4 dichloro-phenoxy-acetic acid (2,4-D). We evaluated both stress biomarkers and the transcriptional expression levels and activity of three enzymes involved in oxidative stress responses. Earthworms were exposed to three sublethal concentration of 2,4-D (3.5, 7, and 14 mg kg−1) for 7 and 14 days. Exposure to 7 and 14 mg kg−1 2,4-D significantly reduced both worm body weight and lysosomal membrane stability (LMS); the latter is a sensitive stress biomarker in coelomocytes. Exposure to 2,4-D caused a pronounced increase in the accumulation of malonedialdehyde (MDA), a marker of oxidative stress, and significantly increased the activity of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD),and glutathione-S-transferase (GST). Compared to expression in controls, the expression levels of the sod, cat, and gst genes increased in worms exposed to all three 2,4-D doses for 7 days. However, after 14 days of exposure, only the expression of the gst gene remained higher than controls. These data provide new insights into the cytotoxicity of 2,4-D in the earthworm E. andrei and should be carefully considered in view of the biological effects of herbicides in soils organisms.