Application of IR-LEGO to heat shock mediated-gene induction in targeted single cells of C. elegans

Ectopic expression via transgene is powerful means for functional analysis of genes of multicellular organisms in vivo. Use of tissue-specific promoters for ectopic expression is limited by their inherent properties to drive gene expression in a restricted temporal-spatial expression pattern. We have developed a novel microscopic system utilizing an infrared laser, IR-LEGO (infrared-laser evoked gene operator) in order to induce heat shock response efficiently in targeted single cells of living organisms, thereby driving expression of a transgene under the control of a heat shock promoter. The system utilizes IR light because we expect that the IR laser can heat biological tissues much more efficiently and is less harmful to cells compared with a Coumarin dye laser, which was used in previous studies. When applied to living nematode C. elegans worms under appropriate conditions, IR-LEGO induced gene expression effectively and reproducibly in targeted single cells. Heat shock-induced cells underwent subsequent development normally, suggesting that the IR-LEGO-mediated heat shock induction does not cause significant cell damages. The system would enable us to induce gene expression in temporally and spatially regulated manners in any organisms, for which transgenic technology is available.