MP7 Toxicogenomics in Environmental Studies
Monday, 14 November 2005: 8:00 AM - 5:30 PM in Exhibit Hall

(GRO-1118-263185) Genomics and physiology of water-borne lead toxicity in freshwater organisms.

Grosell, M¹, Mager, E¹, Wintz, H², Brix, K^{1, 3}, Vulpe, C², ¹ RSMAS, University of Miami, Miami, FL, USA² UC Berkeley, USA³ EcoTox, Key Biscayne, FL, USA

ABSTRACT- Genomics and physiology of water-borne lead toxicity in freshwater organisms M. Grosell1, E. Mager1, H. Wintz2, K.V. Brix1&3, C. Vulpe2. 1 RSMAS, University of Miami, FL, USA 2 UCBerkeley,, CA, USA 3 EcoTox, Key Biscayne, FL, USA Lead (Pb) acts as a potent Ca²⁺ antagonist and water-borne Pb exposure interrupts Ca2+ homeostasis in freshwater organisms. Sublethal consequences of reduced Ca²⁺ uptake from the water include reduced growth in the pulmonate snail, Lymnaea stagnalis and disturbance of whole body Ca²⁺ balance in juvenile fathead minnow. In the pulmonate snail, inhibition of Ca²⁺ uptake and thus shell formation initiate a cascade of effects including alkalosis, and increased Cl^- uptake. Genome wide gene expression in response to sublethal Pb exposure was measured using custom made fathead minnow microarrays hybridized with labeled cDNA obtained from larval fathead minnow. Of multiple clones on the microarray that exhibited significant changes in expression in response to Pb exposure, a subset was chosen for sequencing. Of the sequenced clones, at least five genes appeared highly relevant based on observed physiological consequences of Pb exposure. Up-regulation of genes coding for Ca²⁺ binding proteins, cysteine rich proteins and super oxide dismutase were observed consistent with expectations. In addition, up-regulation of an anion exchanger III like protein was observed in Pb exposed fish. The later observation is consistent with the alkalosis and increased Cl^- uptake seen in Pb exposed snails which perhaps suggest that gene expression responses to Pb exposure in fish and invertebrates display some consistency. Pb induced expression changes of the above genes are currently being verified by qPCR and will be followed by studies of time and concentration dependency of Pb-induced expression changes.

Key words: genomics, water-borne lead toxicity