Single-Copy Insertion of Split-GFP for the Restriction of Germline Expression in Caenorhabditis elegans

Abstract

Gene regulation in C. elegans germ cells depend on transgenerational chromatin modification and small RNA pathways. Germline silencing mechanisms evolved to repress foreign DNA from compromising the transfer of genetic information to progeny. Effective genetic tools that circumvent the silencing machinery will facilitate studies using this model organism. Specifically, translation of heat-shock inducible transgenes is inhibited in the germline making it challenging to transiently express enzymes to modify the genome. Here, we describe a genetic screen design that can be used to identify pathways that prevent germline expression of heat-shock induced transgenes. We use split-GFP (GFP1-10 and GFP11) to confine a genetic screen to germ cells. Stable transgenic lines with germline expression of single-copy integrated GFP11 were produced using MosSCI. The insertion lines will be used in RNAi or chemical mutagenesis screens for the germline de-repression of GFP1-10 expressed under heat-shock promoters. The screen is likely to identify candidate RNAi or chromatin factors involved in repressing heat-shock expression in the germline, particularly from extrachromosomal arrays. Inducible high-level expression in the germline from extrachromosomal arrays would be a valuable tool for large-scale genome engineering.