title: Zonation in the digestive tract of Eisenia fetida: implications in biomarker measurements for toxicity assessment.
abstract: Eisenia fetida is a model species for soil health assessment and different biomarkers that detect either the presence of bioavailable contaminants or their biological effect have been developed. These parameters are performed in a target tissue or whole earthworm, without considering the marked zonation in histological organisation, enzyme activities and gene expression pattern existing along the body. Thus, the present work was aimed at (a) characterising the morphofunctional heterogeneity along the digestive tract of E. fetida in tissue morphology and turnover, lysosomal enzyme markers (β-glucuronidase, β-GUS; hexosaminidase, HEX), lipofuscin contents (LPF) and metallothionein (MT) and catalase (CAT) gene expression; and (b) determining whether the responsiveness to Cd exposure varies among tissues and along the digestive tract. HEX and β-GUS exhibited a heterogeneous distribution pattern along and across the digestive tract and Cd exposure caused a marked decrease of HEX and an increase of β-GUS activity. Likewise, the significant decrease of cell turnover and the induction of MT transcription were was zone-dependent. Therefore, in was concluded that the consideration of the zonation when applying biomarker for toxicity assessment would reduce the intrinsic variability that results from overlooking the marked morphofunctional heterogeneity that exists in annelids along their body axis.
authors.affiliation: Cell Biology & Environmental Toxicology Research Group, Research Centre for Experimental Marine Biology & Biotechnology (PIE) & Zoology & Animal Cell Biology Department (Faculty of Science & Technology), University of the Basque Country, P.O. Box 644, E-48080 Bilbo, Basque Country, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Irizar
authors.affiliation: Cell Biology & Environmental Toxicology Research Group, Research Centre for Experimental Marine Biology & Biotechnology (PIE) & Zoology & Animal Cell Biology Department (Faculty of Science & Technology), University of the Basque Country, P.O. Box 644, E-48080 Bilbo, Basque Country, Spain.
authors.forename: U
authors.initials: U
authors.lastname: Izagirre
authors.affiliation: Cell Biology & Environmental Toxicology Research Group, Research Centre for Experimental Marine Biology & Biotechnology (PIE) & Zoology & Animal Cell Biology Department (Faculty of Science & Technology), University of the Basque Country, P.O. Box 644, E-48080 Bilbo, Basque Country, Spain.
authors.forename: O
authors.initials: O
authors.lastname: Diaz de Cerio
authors.affiliation: Cell Biology & Environmental Toxicology Research Group, Research Centre for Experimental Marine Biology & Biotechnology (PIE) & Zoology & Animal Cell Biology Department (Faculty of Science & Technology), University of the Basque Country, P.O. Box 644, E-48080 Bilbo, Basque Country, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Marigómez
authors.affiliation: Cell Biology & Environmental Toxicology Research Group, Research Centre for Experimental Marine Biology & Biotechnology (PIE) & Zoology & Animal Cell Biology Department (Faculty of Science & Technology), University of the Basque Country, P.O. Box 644, E-48080 Bilbo, Basque Country, Spain. Electronic address: manu.soto@ehu.es.
authors.forename: M
authors.initials: M
authors.lastname: Soto
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000737:chemistry / Q000378:metabolism; D005260:Female; D041981:Gastrointestinal Tract / Q000187:drug effects / Q000378:metabolism*; D009835:Oligochaeta; D012989:Soil Pollutants / Q000633:toxicity*; D018675:Toxicity Tests / Q000379:methods
chemical_list: D015415:Biomarkers; D012989:Soil Pollutants
keywords: Digestive tract; Eisenia fetida; Lysosomal markers; Molecular biomarkers; Toxicity; Zonation