Transgenic expression construct with SL1 (gene of interest) + SL2 (GFP)?

Hi everyone,

I am attempting to create multi-copy transgenic arrays of a gene of interest in C. elegans with a fluorescent marker. However I don’t want a bulky GFP tag to interfere with protein function for the gene of interest.

In reading the recent review paper by Jeremy Nance and Christian Frokjaer-Jensen (“The C. elegans Transgenic Toolbox”) they mention an SL1 + SL2 system. However the two citations don’t seem to show an implementation of what I’m thinking of; instead they are general discussions of trans-splicing or nematode genomics. (They cite Cutter et al 2009, and Blumenthal’s 2009 WormBook chapter on operons). While both of these are valuable resources I am still interested in finding out if someone has used, and published the type of operon-based transgenic system I am imagining: specifically,

ubiquitous promoter (plet-858 perhaps)–SL1 [Gene of Interest] --[SL2 GFP] --UTR (unc54? seems like the standard).

Does anyone 1) have something like this or 2) know someone who does? My email address is and I would be happy to hear from you! I am aware of some alternative methods for what I’m proposing including 2A self-cleaving peptides. Happy to hear about them as well and whether they work or not. Sounds like it may have some challenges based on the Nance review.


From the description and the promoter choice, sounds like you just want to overexpress a gene throughout the whole worm body? If so, this design should work. It is a standard way to use SL2::GFP/RFP fused with a gene of interest to monitor its transcriptional level/ensure transgene is carried by the transgenic worms (mosaic or not). From my understanding, all promoters naturally carry an SL1 type of splicing signal, so there is no need to include an extra SL1 sequence between your promoter of choice and the gene of interest.

But do note this system won’t label your protein on the peptide level, so it won’t tell you your gene’s translational level, nor can you do subcellular localization/excretion studies of your protein of interest.

This is one paper I know that used an operon transgene. Perhaps you can find the sequences there.