Project name: Caenorhabditis elegans

Description: Reports that low-intensity microwave radiation can induce heat-shock reporter gene expression in the nematode, Caenorhabditis elegans, have recently been reinterpreted as a subtle thermal effect caused by very slight heating. This study used a microwave exposure system (1.0 GHz, 0.5 W power input; SAR 0.9-3 mW kg-1 for 6-well plates) that minimises the temperature differential between sham and exposed conditions to ≤ 0.1°C. Comparable measurement and simulation studies of SAR distribution within this exposure system are presented. We compared 5 Affymetrix gene-arrays of pooled triplicate RNA populations from sham-exposed L4/adult worms against 5 gene-arrays of pooled RNA from microwave-exposed worms (taken from the same source population in each run). Few genes showed consistent expression changes across all 5 comparisons, and all such expression changes appeared modest after applying standard normalisation procedures (≤ 30% up- or down-regulated). The number of statistically significant differences in gene expression (846) was less than the false-positive rate expected by chance (1131). As one example, an apparent up-regulation of the vit-3 vitellogenin gene by microwave exposure was not mirrored by similar changes affecting the other co-regulated members of the same vit gene family. We conclude that the pattern of gene expression in L4/adult C elegans is not substantially perturbed by low-intensity microwave radiation, and that the minor changes observed in this study may well be explicable as false positives. As a check on the sensitivity of the Affymetrix gene-arrays used, we also compared RNA samples from N2 worms subjected to a sub-heat-shock treatment (28ºC) against controls kept at 26 ºC (but using only 2 gene arrays per condition). After similar normalisation, many more genes (3712) showed substantial expression changes (i.e. > 2-fold at p 10-fold). However, further replication and confirmation by real-time RT-PCR would be needed to establish how many of these changes might also be false positives.Experimenter name: Adam DaweExperimenter phone: +27 21 959 2364adam@sanbi.ac.zaExperimenter institute: South African National Bioinformatics InstituteExperimenter address: University of Western Cape, Old Chemistry Building, University of Western Cape, Modderdam Road, Bellville 7530, CapetownExperimenter zip/postal_code: 7530Experimenter country: South AfricaKeywords: Microwave radiation, gene expression, gene arrays, Caenorhabditis elegansOverall design: 14 samples were used in this experiment

Data type: Transcriptome or Gene expression

Sample scope: Multiisolate

Relevance: ModelOrganism

Release date: 2009-03-12

Last updated: 2008-03-11