Rat traps: filling the toolbox for manipulating the rat genome

Table 2 Comparison of available rat mutagenesis techniques

Technique	Targeted or random	Advantages	Disadvantages
ENU mutagenesis target-selected mutagenesis	Random	High mutation efficiency	Mutation discovery is relatively laborious
		Easily scalable	Background mutations
		Allows for allelic series
Transposon-tagged mutagenesis	Random	Gene insertions easily detectable by reporter gene cassettes	Relatively low mutation efficiency
		Integration site easy to identify	Biased genomic integration pattern
ZFN-mediated gene targeting	Targeted	Allows gene targeting by NHEJ and theoretically allows homologous recombination	Modular assembly of zinc-finger arrays is relatively unsuccessful
		High efficiency in introducing DSBs	Commercial ZFNs are expensive
Homologous recombination in ES or iPS cells	Targeted	Enables targeted knockouts, knock-ins and conditional alleles	Homologous recombination has still not been shown in rat ES and iPS cells

ENU, N-ethyl-N-nitrosourea; ES, embryonic stem; iPS, induced pluripotent stem; ZFN, zinc-finger nuclease; NHEJ, nonhomologous end joining; DSBs, double-strand breaks.

ISSN: 1474-760X