Light and Scanning-Electron Microscopic Study of Eisenia fetida Coelomocytes after Copper Oxychloride Exposure

Abstract

Morphological alterations in Eisenia fetida coelomocytes are recommended biomarkers for soil contamination surveys. Copper oxychloride is a widely used agrochemical agent that causes excessive amounts of Cu accumulation in soils. The present study is a light and electron microscopic investigation of the morphological alterations in coelomocytes of E. fetida exposed to copper oxychloride. Exposure concentration was 350 mg/kg of artificial soil and exposure duration was 7 or 14 days. Colelomocytes were extrused into an ethanol and guaicol glyceryl (GGE) containing modified Hanks' balanced solution (M-HBSS-GGE) by a simple low vacuum holding device and processed for light and scanning electron microscopy. Lipid peroxidation (LP) in the earthworms was also measured to evaluate oxidative stress (OS). Swelling and vesicular deformation were the early signs of toxicity in eleocytes after 7 days. After 14 days, complete loss of vesicles and spongy surface were observed in eleocytes. Granulocytes showed more dramatical changes. Nucleus fragmentation and membrane rupture were observed after 14 days. Increased LP in the earthworms was accompanying these changes. As a result, along with biochemical markers such as LP, light and scanning electron microscopic changes in E.fetida eleocytes and granulocytes can be considered as valuable biomarkers of copper oxychloride toxicity. Evaluation of those markers in the future studies can constitute an important early warning in terms of soil accumulation.