Guide to Moving Genetic Technologies into Insects

Huang et al (2016) have published a short review on insect genetic technologies in the Journal of Genetics and Genomics that could serve as a useful guide for those considering the development of genetic technologies for ‘their’ insect system.

Transposon

Transposon systems are seen by Huang et al (2016) as critical components of an insect genetic engineering toolbox.

The authors review briefly the major developments in the creation of insect genetic technologies and these include the development of vectors for transgene integration and versatile dominant visible genetic marker systems.  Secondary developments, according to the authors, were those that used the basic vector and marker systems to create new technologies.  These secondary technologies include binary expression systems with the Gal4/UAS system being particularly popular, site-specific recombination systems like the FLP-FRT system, gene targeting by homologous recombination, site-specific recombination as a transgene integration method e.g. phiC31 , site-specific DNA breakage in genome editing including zinc finger nucleases, TALENs and the CRISPR/Cas9 system, and finally, ‘gene drive’ as a tool for insect management.

For reasons of length, the discussion of these topics was not highly detailed but sufficient to give readers a sense of the technologies and some key references from which to delve deeper.

Until other technology is developed, the microinjection of pre-blastoderm embyros is the only reliable way to deliver genetic technologies to the germline to make heritable changes in the genome.

The last section of the paper deals with “Practical Considerations” for developing insect genetic technology platforms in ‘non-model’ insects.  The authors emphasize the important and essential role injection of pre-blastoderm embryos plays as a mode of delivery of DNA, RNA and protein components of the various technologies described.  Until alternative means of delivering technologies to the germline are developed the range of insects amenable to genetic manipulations of their germline will remain limited to only those whose embryos can be readily manipulated.  Systems for expressing requisite enzymes to mediate integrations, transpositions or gene editing are also important and this requires promoters that are functional in the insect of interest.  Once embryos are injected the resulting adults are put in various mating schemes and without the ability to do simple genetics the prospects for successfully developing genome manipulation platforms are poor.

phiC31

The phiC31 site-specific recombination system is another platform the authors recommend insect biologists have for ‘their’ insect systems.

The authors end with a description of the stages they recommend be followed in getting an insect on line for genome manipulations.  They suggest that transposon-based gene vector systems (they recommend piggyBac) are an important first step followed by the establishment of a site-specific recombination-mediated transgene integration system such as phiC31.  Transposons are useful for inserting the appropriate attachment sites through the genome, among other things.  Finally, Huang et al. (2016) suggest that an RNA-guided gene editing system be developed in parallel with the transposon and site-specific integration system.  Assembling these basic systems would provide investigators with opportunities to perform genome manipulations necessary for forward and reverse genetic analyses of their favorite insect.

Huang, Y., Z. Liu, and Y.S. Rong, Genome Editing: From Drosophila to Non-Model Insects and Beyond. Journal of Genetics and Genomics, 2016. 43(5): p. 263-272

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