title: Sublethal mechanisms of Pb and Zn toxicity to the purple sea urchin (Strongylocentrotus purpuratus) during early development.
abstract: In order to understand sublethal mechanisms of lead (Pb) and zinc (Zn) toxicity, developing sea urchins were exposed continuously from 3h post-fertilization (eggs) to 96 h (pluteus larvae) to 55 (±2.4) μgPb/L or 117 (±11)μgZn/L, representing ~ 70% of the EC50 for normal 72 h development. Growth, unidirectional Ca uptake rates, whole body ion concentrations (Na, K, Ca, Mg), Ca(2+) ATPase activity, and metal bioaccumulation were monitored every 12h over this period. Pb exhibited marked bioaccumulation whereas Zn was well-regulated, and both metals had little effect on growth, measured as larval dry weight, or on Na, K, or Mg concentrations. Unidirectional Ca uptake rates (measured by (45)Ca incorporation) were severely inhibited by both metals, resulting in lower levels of whole body Ca accumulation. The greatest disruption occurred at gastrulation. Ca(2+) ATPase activity was also significantly inhibited by Zn but not by Pb. Interestingly, embryos exposed to Pb showed some capacity for recovery, as Ca(2+)ATPase activities increased, Ca uptake rates returned to normal intermittently, and whole body Ca levels were restored to control values by 72-96 h of development. This did not occur with Zn exposure. Both Pb and Zn rendered their toxic effects through disruption of Ca homeostasis, though likely through different proximate mechanisms. We recommend studying the toxicity of these contaminants periodically throughout development as an effective way to detect sublethal effects, which may not be displayed at the traditional toxicity test endpoint of 72 h.
authors: McMaster University, Department of Biology, Hamilton, Ontario L8S 4K1, Canada; Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada. Electronic address: margaret_tellis@yahoo.com.
authors: Margaret S
authors: MS
authors: Tellis
authors: Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada; Instituto de Ciências Biológicas, Universidade Federal do Rio Grande (FURG), 96203-900 Rio Grande, Rio Grande do Sul, Brazil.
authors: Mariana M
authors: MM
authors: Lauer
authors: McMaster University, Department of Biology, Hamilton, Ontario L8S 4K1, Canada; Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada.
authors: Sunita
authors: S
authors: Nadella
authors: Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada; Instituto de Ciências Biológicas, Universidade Federal do Rio Grande (FURG), 96203-900 Rio Grande, Rio Grande do Sul, Brazil.
authors: Adalto
authors: A
authors: Bianchini
authors: McMaster University, Department of Biology, Hamilton, Ontario L8S 4K1, Canada; Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada.
authors: Chris M
authors: CM
authors: Wood
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects; D007814:Larva / Q000187:drug effects; D007854:Lead / Q000633:toxicity*; D047270:Strongylocentrotus purpuratus / Q000187:drug effects*; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015032:Zinc / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D007854:Lead; D000251:Adenosine Triphosphatases; D015032:Zinc; D002118:Calcium
keywords: Calcification; Echinoderm; Embryonic development; Lead; Spicule; Toxicity; Zinc