Genome Editing in C. elegans and Other Nematode Species.

Takuma Sugi

doi:10.3390/ijms17030295

Abstract

Caenorhabditis elegans, a 1 mm long free-living nematode, is a popular model animal that has been widely utilized for genetic investigations of various biological processes. Characteristic features that make C. elegans a powerful model of choice for eukaryotic genetic studies include its rapid life cycle (development from egg to adult in 3.5 days at 20 °C), well-annotated genome, simple morphology (comprising only 959 somatic cells in the hermaphrodite), and transparency (which facilitates non-invasive fluorescence observations). However, early approaches to introducing mutations in the C. elegans genome, such as chemical mutagenesis and imprecise excision of transposons, have required large-scale mutagenesis screens. To avoid this laborious and time-consuming procedure, genome editing technologies have been increasingly used in nematodes including C. briggsae and Pristionchus pacificus, thereby facilitating their genetic analyses. Here, I review the recent progress in genome editing technologies using zinc-finger nucleases (ZFNs), transcriptional activator-like nucleases (TALENs), and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 in nematodes and offer perspectives on their use in the future.

Highlights

The nematode C. elegans became a powerful model organism just over 50 years ago [1]
transcriptional activator-like nucleases (TALENs)-mediated genome editing has been used for the targeted inactivation of the paxt-1 gene, which encodes a subunit of the XRN2 complex which is a eukaryotic exoribonuclease for processing and degrading various substrates [61]
The authors have found that the nucleosome remodeling factor (NURF) complex has acquired a unique role in the sperm/oocyte decision of C. briggsae [62]

Summary

Introduction

The nematode C. elegans became a powerful model organism just over 50 years ago [1]. This tiny animal has greatly contributed to investigations of the functions of genes in development and cellular biology. Screening of worms with deletions of specific target DNA by the C. elegans Gene Knockout Consortium and the Japan National Bioresource Project has offered opportunities to examine the phenotypic effects of a targeted gene knock-out. These resources do not completely include mutants with deletions in a desired genomic region. A strategy for inducing a stable gene knock-in at a desired genomic location has been required in the nematode research field Due to these requirements for targeted genome editing, C. elegans geneticists have developed methods based on the Mos transposon system [11,12]. I provide a historical overview of this research field and discuss recent implementations of genome editing techniques in nematodes

Site-Restricted Editing by Mos1

Imprecise and Precise Repair Using ssOligo and dsDNA

Optimization of the CRISPR System

Important Results Achieved Using Genome Editing Techniques

Conclusions