title: Optimization of NRU assay in primary cultures of Eisenia fetida for metal toxicity assessment.
abstract: Coelomocytes, immunocompetent cells of lumbricids, have received special attention for ecotoxicological studies due to their sensibility to pollutants. Their in vitro responses are commonly quantified after in vivo exposure to real or spiked soils. Alternatively, quantifications of in vitro responses after in vitro exposure are being studied. Within this framework, the present study aimed at optimizing the neutral red uptake (NRU) assay in primary culture of Eisenia fetida coelomocytes for its application in soil toxicity testing. Optimized assay conditions were: earthworm depuration for 24 h before retrieving coelomocytes by electric extrusion; 2 × 10(5) seeded cells/well (200 µl) for the NRU assay and incubation for 1 h with neutral red dye. Supplementation of the culture medium with serum was not compatible with the NRU assay, but coelomocytes could be maintained with high viability for 3 days in a serum-free medium without replenishment. Thus, primary cultures were used for 24 h in vitro toxicity testing after exposure to different concentrations of Cd, Cu, Ni and Pb (ranging from 0.1 to 100 μg/ml). Primary cultures were sensitive to metals, the viability declining in a dose-dependent manner. The toxicity rank was, from high to low, Pb > Ni > Cd > Cu. Therefore, it can be concluded that the NRU assay in coelomocytes in primary cultures provides a sensitive and prompt response after in vitro exposure to metals.
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. 11 Box 644, 48080, Bilbao, Basque Country, Spain.
authors.forename: Amaia
authors.initials: A
authors.lastname: Irizar
authors.forename: Daniel
authors.initials: D
authors.lastname: Duarte
authors.forename: Lucia
authors.initials: L
authors.lastname: Guilhermino
authors.forename: Ionan
authors.initials: I
authors.lastname: Marigómez
authors.forename: Manu
authors.initials: M
authors.lastname: Soto
mesh_terms: D000818:Animals; D001681:Biological Assay; D002478:Cells, Cultured; D019216:Metals, Heavy / Q000633:toxicity*; D009499:Neutral Red; D009835:Oligochaeta / Q000166:cytology* / Q000187:drug effects*; D061251:Primary Cell Culture; D012989:Soil Pollutants / Q000633:toxicity*; D018675:Toxicity Tests
chemical_list: D019216:Metals, Heavy; D012989:Soil Pollutants; D009499:Neutral Red