Transgenerational Sterility of a Transgenic C. elegans: A Cautionary Tale

The integration of fluorescent protein tags (GFP, mScarlet, mNeon, etc) by CRISPR is often inefficient due to the size of the tags (hundreds of base pairs). To facilitate fluorescent tagging, the split-GFP and split-Scarlet systems have been optimized for use in <i>C. elegans</i> (Goudeau et al., 2021). In <i>C. elegans</i> , <i>glh-1 ::T2A::wrmScarlet(1-10)</i> allows germline gene expression of red fusion proteins. While initial studies reported wild-type broods at both permissive and non-permissive temperatures, we report here that at least one such transgene confers sterility after continuous culturing at 25.5 °C. This serves as a cautionary tale for use of the <i>glh-1</i> driver and/or T2A::mScarlet fusions to this protein.