Specialized Chromosomes and Their Uses in Caenorhabditis elegans - Caenorhabditis Elegans: Molecular Genetics and Development - page 55

However, preparation of nematodes and materials for gene bombardment is signif-
icantly more labor and material intensive than for microinjection, and it takes longer
to generate transgenic strains.
7. Single-Copy Insertion by MosSCI
Recently, an approach for obtaining integration of transgenes as single copies at a
defined genomic site had been developed ( Frokjaer-Jensen et al., 2008 ). Mos1-
mediated single-copy insertion (MosSCI) takes advantage of the Mos transposable
element ( Granger et al., 2004; Robert and Bessereau, 2009; Robert et al., 2009 )to
introduce modified reporter constructs directly into the genome ( Fig. 11 ).
In this approach, the construct of interest is inserted into a vector containing
flanking homology to the genomic region surrounding a known Mos element.
This vector includes a WT copy of unc-119 gene for use as a positive selection
marker. This insertion vector, along with a clone carrying the transposase gene under
the control of a heat-shock promoter and fluorescent reporters are injected into
anunc-119 mutant strain that harbors a single Mos1 element in an intergenic region
of the genome. (Vector and strain details are available at http://sites.google.com/site/
jorgensenmossci/Home ).
Animals containing the assembled transgenic array express the coinjected fluo-
rescent markers. Heat-shock activation of the transposase in these animals leads to
excision of the Mos1 element. In rare instances, the resulting double strand break is
Fig. 11 MosSci single-copy insertion of transgenes. In this approach, a reporter construct is engi-
neered into a modified Mos1 transposon. This construct, along with a clone carrying the activating
transposase gene under the control of a heat-shock promoter, is injected into a carrier strain that harbors
a single Mos1 integration site in an intergenic region of the genome. Subsequent induction of the
transposase results in insertion of the hybrid transposon into the genome.