homology assisted CRISPR knock-in (HACK)

The homology assisted CRISPR knock-in (HACK) method allows for in vivo conversion of existing GAL4 constructs into constructs expressing QF2, GAL80 or split-GAL4 effectors. A target GAL4 insertion is combined with genomic source of Cas9 nuclease and a donor insertion harboring both a guide RNA targeting GAL4 and the effector coding sequence flanked by homology arms to GAL4.  


Converting GAL4 constructs to QF2 constructs was described in Lin and Potter (2016) “Editing Transgenic DNA Components by Inducible Gene Replacement in Drosophila melanogaster”.

Converting GAL4 constructs to GAL80 or split-GAL4 constructs was described in Xie et al. (2018) “A Genetic Toolkit for Dissecting Dopamine Circuit Function in Drosophila”.

Conversion Efficiency

The efficiency of GAL4 conversion is influenced by both the distance and orientation of the donor insertion relative to the target GAL4 insertion. See the papers listed above for recommendations.

HACKed GAL4 Lines

Lin and Potter used the HACK system to convert 23 commonly used GAL4s into QF2-expressing lines.  You can find them on our QF2 page.

Lists of potential GAL4 target lines can be found on our GAL4 page.

We currently have the following donor lines:

Related links   GAL4    GAL80   QF