Koichi Hasegawa et al. (2006) East Asia C. elegans Meeting "A rapid and inexpensive method to screen common foods that reduce the action of acrylamide, a harmful substance in food"

Johji Miwa, Koichi Hasegawa, Kaname Tsutsumiuchi, Satsuki Miwa, Hajime Taniguchi, Kazunori Isomura

[East Asia C. elegans Meeting, 2006]

In April 2002, the NFA and Stockholm University reported that acrylamide was formed in high concentrations during the frying or baking of carbohydrate-rich foods. Because acrylamide had shown neurotoxicity, mutagenicity and carcinogenicity in experimental animals and cultured cells, the finding focused the world's attention on this shocking public health problem. We are analyzing the actions of acrylamide by using the genetic, genomic, and proteomic strengths of Caenorhabditis elegans as a whole animal system for toxicomics research. We here describe a rapid method to detect acrylamide and also a method to screen common foods that detoxify acrylamide or reduce its actions. First, to find biomarkers that respond to acrylamide, we used whole genome DNA microarray analysis and protein two-dimensional gel electrophoresis (2-DE). At high concentration of 500 mg/L acrylamide, we found 23 up-regulated glutathione S-transferase (GST) genes by microarray and identified four up-regulated GST proteins by 2-DE. Second, we selected the gst-4 gene, which exhibited the greatest up-regulation by microarray and 2-DE, and constructed a gst-4::gfp fusion gene used to transform C. elegans into a biosensor for acrylamide. We could detect the GFP expression signal from 4 hours after 500 mg/L acrylamide exposure, and from only 1 hour after only 0.05 μg/L glycidamide exposure. Third, we cultured these transgenic nematodes in S-medium containing 500 mg/L acrylamide with or without several foods, and monitored GFP expression levels over time. GFP levels decreased to the control level when transgenic nematodes were cultured in S-medium containing acrylamide together with commercially available powdered green tea or skim milk, suggesting that tea and skim milk (or additives to them) detoxified acrylamide or prevented its GST-inducing action. The methodology reported here should be applicable to detection of other harmful substances and screening of foods that reduce their harmfulness or action, through appropriately constructed visible biosensors.