SREL Reprint #2885

 

 

 

Evidence for Biogenic Pyromorphite Formation by the Nematode Caenorhabditis elegans

B. P. Jackson1, P. L. Williams2, A. Lanzirotti3, and P. M. Bertsch1

1Advanced Analytical Center for Environmental Sciences, Savannah River Ecology Laboratory,
University of Georgia, Aiken, South Carolina 29802
2Department of Environmental Health Science, University of Georgia, Athens, Georgia 30602-2102
3Consortium for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637

Abstract: The determination of chemical speciation and spatial distribution is a prerequisite for a mechanistic understanding of contaminant bioavailability and toxicity to an organism. We have employed synchrotron X-ray techniques to study Cu and Pb speciation and spatial distribution in the soil nematode Caenorhabditis elegans. Nematodes were exposed to each metal ion singly or simultaneously in solution for 24 h and were then rinsed thoroughly and preserved in formalin for transportation to the National Synchrotron Light Source. Experiments were conducted at the microprobe beamline X26A employing a focused beam of approximately 10 µm in diameter. Nematodes were mounted in agar gel on Kapton tape. Two-dimensional elemental maps for Cu- and Pb-exposed nematodes were collected in fluorescence mode. Copper was homogeneously distributed throughout the body of the nematode, exclusively in the anterior pharynx region. Detectable localized concentrations of Pb in C. elegans occurred at aqueous exposure concentrations of 2.4 µM. Micro X-ray diffraction of these Pb hotspots gave a diffraction pattern indicating a crystalline Pb solid that was consistent with the Pb phosphate, pyromorphite. Biogenic inorganic phosphate granule formation is relatively common in soil invertebrates; however, these phosphates are typically amorphous, and we beleive that this is the first report of crystalline pyromorphite formed internally in an organism.

SREL Reprint #2885

Jackson, B. P., P. L. Williams, A. Lanzirotti, and P. M. Bertsch. 2005. Evidence for biogenic pyromorphite formation by the nematode Caenorhabditis elegans. Environmental Science & Technology 39:5620-5625.

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