Expressional artifact caused by a co-injection marker rol-6 in C. elegans.

Hoyong Jin,Byunghyuk Kim,Scott W Emmons,Denis Dupuy

doi:10.1371/journal.pone.0224533

Abstract

In transgenic research, selection markers have greatly facilitated the generation of transgenic animals. A prerequisite for a suitable selection marker to be used along with a test gene of interest is that the marker should not affect the phenotype of interest in transformed animals. One of the most common selection markers used in C. elegans transgenic approaches is the rol-6 co-injection marker, which induces a behavioral roller phenotype due to a cuticle defect but is not known to have other side effects. However, we found that the rol-6 co-injection marker can cause expression of GFP in the test sequence in a male-specific interneuron called CP09. We found that the rol-6 gene sequence included in the marker plasmid is responsible for this unwanted expression. Accordingly, the use of the rol-6 co-injection marker is not recommended when researchers intend to examine precise expression or perform functional studies especially targeting male C. elegans neurons. The rol-6 sequence region we identified can be used to drive a specific expression in CP09 neuron for future research.

Highlights

Efficient transgenic techniques are used in various model systems to detect gene expression and assess genetic function
In the nematode Caenorhabditis elegans, for example, gene expression can be monitored using transgenic worms generated by a simple, gonadal microinjection of a plasmid that drives GFP expression under the control of a promoter for a gene of interest [1]
We noticed that in eight out of 10 transgenic lines, GFP was expressed in the CP09 neuron among other diverse neurons [9]

Summary

Introduction

Efficient transgenic techniques are used in various model systems to detect gene expression and assess genetic function. Study, we report that the widely-used rol-6 marker unexpectedly activates the test gene in a male interneuron called CP09 in C. elegans. During the course of experiments to determine the tissue-specific expression pattern of 10 putative synaptic genes in C. elegans, we generated transgenic worms with promoter::GFP test genes using rol-6(su1006) as a co-injection marker (for information on the genes and the promoter fragments assayed, see S1 Table).

Results

Conclusion