Identification of mutations in Caenorhabditis elegans that cause resistance to high levels of dietary zinc and analysis using a genome-wide map of single-nucleotide polymorphisms scored by pyrosequencing

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 C. elegans to be resistant to high levels of dietary zinc. Nineteen mutations were identified that confer significant resistance to supplemental dietary zinc. To determine the map positions of these mutations, we developed a genome-wide 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 nineteen 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.

Key Words: C. elegans, SNP mapping, metal biology, pyrosequencing, zinc

Online ISS 1091-6490
Copyright 2008 by the Genetics Society of America
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