Riboflavin content of coelomocytes in earthworm (Dendrodrilus rubidus) field populations as a molecular biomarker of soil metal pollution

The effect of Pb + Zn on coelomocyte riboflavin content in the epigeic earthworm Dendrodrilus rubidus inhabiting three metalliferous soils and one reference soil was measured by flow cytometry and spectrofluorimetry. A reciprocal polluted↔unpolluted worm transfer experiment (4-week exposure) was also performed. High proportions of autofluorescent eleocytes were counted in worms from all localities, but intense riboflavin-derived autofluorescence was detectable only in reference worm eleocytes. Other findings were: (i) fluorophore(s) other than riboflavin is/are responsible for eleocyte autofluorescence in residents of metalliferous soils; (ii) riboflavin content was reduced in the eleocytes of worms transferred from unpolluted to metal-polluted soil; (iii) the riboflavin content of D. rubidus eleocytes is a promising biomarker of exposure; (iv) COII mitochondrial genotyping revealed that the reference population is genetically distinct from the three mine populations; (v) metal exposure rather than genotype is probably the main determinant of inter-population differences in eleocyte riboflavin status.     

Aporrectodea caliginosa, a suitable earthworm species for field based genotoxicity assessment?

There is a growing interest for the application of biomakers to field-collected earthworms. Therefore we have evaluated the usability of native populations of endogeic, widely distributed earthworm Aporrectodea caliginosa in the assessment of soil genotoxicity using the Comet assay. Validation of the Comet assay on earthworm coelomocytes has been established using commercially available Eisenia fetida exposed to copper, cadmium, and pentachlorophenol, along with A. caliginosa exposed to copper in a filter paper contact test. Neutral red retention time (NRRT) assay was conducted on copper exposed and field-collected earthworms. Significant DNA and lysosomal damage was measured using Comet and NRRT assays in native populations of A. caliginosa sampled from the polluted soils in the urban area in comparison to the earthworms from the reference site. The results of this study confirm the employment of A. caliginosa as a suitable species for the in situ soil toxicity and genotoxicity field surveys.