Originally published as Genetics Published Articles Ahead of Print on May 27, 2008.

Genetics, Vol. 179, 811-828, June 2008, Copyright © 2008
doi:10.1534/genetics.107.084384

Identification of Mutations in Caenorhabditis elegans That Cause Resistance to High Levels of Dietary Zinc and Analysis Using a Genomewide Map of Single Nucleotide Polymorphisms Scored by Pyrosequencing

Janelle J. Bruinsma1, Daniel L. Schneider, Diana E. Davis and Kerry Kornfeld2

Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri 63110

2 Corresponding author: Department of Developmental Biology, Washington University School of Medicine, Campus Box 8103, 660 S. Euclid Ave., St. Louis, MO 63110.
E-mail: kornfeld{at}wustl.edu

Zinc plays many critical roles in biological systems: zinc bound to proteins has structural and catalytic functions, and zinc is proposed to act as a signaling molecule. Because zinc deficiency and excess result in toxicity, animals have evolved sophisticated mechanisms for zinc metabolism and homeostasis. However, these mechanisms remain poorly defined. To identify genes involved in zinc metabolism, we conducted a forward genetic screen for chemically induced mutations that cause Caenorhabditis elegans to be resistant to high levels of dietary zinc. Nineteen mutations that confer significant resistance to supplemental dietary zinc were identified. To determine the map positions of these mutations, we developed a genomewide map of single nucleotide polymorphisms (SNPs) that can be scored by the high-throughput method of DNA pyrosequencing. This map was used to determine the approximate chromosomal position of each mutation, and the accuracy of this approach was verified by conducting three-factor mapping experiments with mutations that cause visible phenotypes. This is a generally applicable mapping approach that can be used to position a wide variety of C. elegans mutations. The mapping experiments demonstrate that the 19 mutations identify at least three genes that, when mutated, confer resistance to toxicity caused by supplemental dietary zinc. These genes are likely to be involved in zinc metabolism, and the analysis of these genes will provide insights into mechanisms of excess zinc toxicity.