title: Metallothionein in the freshwater gastropod Melanopsis dufouri chronically exposed to cadmium: a methodological approach.
abstract: Previous studies have demonstrated that the use of differential pulse polarography (DPP) for metallothionein (MT) determination in marine gastropod tissues, particularly the digestive gland, requires taking into account the presence of heat-stable high molecular weight compounds that exhibit polarographic signal. In the present paper, similar compounds were identified in tissues from the freshwater snail Melanopsis dufouri which also interfere with MT determination by DPP and, due to their silver binding capacity, also interfere in the silver assay for MT quantification. Ultrafiltration seems to be effective in removing these high molecular weight compounds from heat-denatured homogenate supernatant allowing direct MT quantification by DPP. A fully validated procedure for metallothionein determination in M. dufouri is described. In spite of a considerable accumulation of cadmium in the visceral complex of M. dufouri following exposure to 100 microg CdL(-1) for 8 weeks (up to 37 microgg(-1)) only a small increase in MT concentration was found.
authors.affiliation: Department of Functional Biology, Faculty of Biological Sciences, University of Valencia, Dr Moliner 50, 46100 Burjassot, Valencia, Spain. Rocio.Urena@uv.es
authors.forename: Rocío
authors.initials: R
authors.lastname: Ureña
authors.forename: Maria
authors.initials: M
authors.lastname: João Bebianno
authors.forename: Jose
authors.initials: J
authors.lastname: Del Ramo
authors.forename: Amparo
authors.initials: A
authors.lastname: Torreblanca
mesh_terms: D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D008668:Metallothionein / Q000378:metabolism; D012908:Snails / Q000187:drug effects* / Q000378:metabolism; D036401:Toxicity Tests, Chronic / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D002104:Cadmium; D008668:Metallothionein