title: Cadmium content of the marine sponge Microciona prolifera, other sponges, water and sediment from the eastern Florida panhandle: possible effects on Microciona cell aggregation and potential roles of low pH and low salinity.
abstract: Marine sponges from shallow bays and estuaries along the Florida panhandle contained cadmium (Cd), 1.78-27.9 microg g(-1) (dry weight). Levels > 7 microg g(-1) were never found in a variety of other benthic invertebrates. Water levels of Cd were of the order 0.22-0.43 microg ml(-1) and did not differ significantly between the two study areas (Panacea and St. Joseph Bay). Cd in organic sediment however, was significantly (P = 0.033) higher around Panacea (0.343 +/- 0.063 S.E.M.) than in St. Joseph Bay (0.18 +/-0.223 S.E.M.). Salinity of 10 and pH 6.5 were recorded following heavy rains, and can constitute a hostile environment for these organisms. Temporal variations of Cd and Cu but not Zn were observed in Microciona prolifera over a period of 2 years in St. Joseph Bay, and a negative correlation was observed between Cd content and the Ca(2+)-induced aggregation of Microciona cells suspended in Ca2+/Mg(2+)-free artificial seawater. Cells unresponsive to Ca2+ aggregated in response to releasers of Ca2+ from internal stores (thapsigargin, A23187 and tetredecylamine), suggesting that they were viable but dormant. In vitro studies showed that Cd2+ is about equipotent with Ca2+ in inducing aggregation of Microciona cells, whereas lower concentrations (1-2 x 10(-3) M), added 10 min before inducing aggregation with CaCl2, inhibited aggregation, possibly by blocking Ca2+ uptake. Microciona contained a metallothionein (MT)-like protein. Taken together these results suggest that naturally-acquired Cd may interfere with cell regulatory processes in Microciona. Possible effects of low pH and salinity on Cd uptake and detrimental effects on cell function are discussed.
authors.affiliation: Department of Pharmacology and Toxicology, University of Western Ontario, London, Canada. rphilp@julian.uwo.ca
authors.forename: R B
authors.initials: RB
authors.lastname: Philp
mesh_terms: D000818:Animals; D002104:Cadmium / Q000032:analysis* / Q000494:pharmacology*; D002449:Cell Aggregation / Q000187:drug effects; D005431:Florida; D005618:Fresh Water; D019015:Geologic Sediments / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D011161:Porifera / Q000737:chemistry*; D012492:Salts; D012623:Seawater / Q000737:chemistry*
chemical_list: D012492:Salts; D002104:Cadmium