Screening and SNP mapping of copper-resistant mutations in C. elegans.

Abstract

Copper plays critical roles in biological system; however, it is toxic in excess. To identify novel genes involved in copper metabolism, we performed a whole genome-wide genetic screen in C. elegans model organism to search for mutants which are resistant to excessive copper. Wild type (N2) L4 worms were mutagenized with ethylmethane sulfonate (EMS), and the F₂progeny were screened on culture medium with excess copper. Two copper-resistant mutants, ms₁and ms₂, were recovered from the screening of 100 000 hyploid genomes. No obvious developmental defects were observed in ms₁and ms₂mutants, and they were able to grow into adults on screen medium plate, but N₂worms arrested in L₁stage. Results of backcross test suggested that copper-resistant phenotype in ms₁may be controlled by a single recessive gene, but probably there are mutations in multiple genes in ms₂, as no copper resistant worms could be found in F₂progeny when ms₂mutants were backcrossed with N₂worms. To determine the mutation positions of ms₁, we employed single nucleotide polymorphisms (SNPs) mapping. Our mapping results indicated that ms₁mutation is on chromosome II (LGII). By analysis of 8 SNP markers from -18 to 23 on LGII, we found that ms₁mutation is at approximately LGII:-6. Further study on ms₁mutants will provide insights into copper metabolism and its regulation.