Traditionally, transgenic flies were created using P-element mediated systems that result in semi-random insertions into the genome. Depending on the insertion location, there may also be position effects on transgene expression from nearby regulatory sequences. The phiC31 (ΦC31) integrase system allows for site-specific integration of transgenes. Further, many attP sites have been characterized for position effects.

The bacteriophage phiC31 integrase is a recombinase that mediates the sequence-specific recombination between two attachment sites, attB and attP. Because these two sites differ in their sequence composition, and recombination results in generation of two unique sites, attR and attL, phiC31 integration is unidirectional (ie., it cannot be remobilized by phiC31 itself). For more information about the phiC31 system, see FlyC31.

For stocks carrying Bxb1 integrase see our Alternative site-specific recombination page.

Primary references:

P{CaryP} insertions: Groth et al. 2004  and Szabad et al. 2012

PBac{y[+]-attP} insertions:  Venken et al. 2006

M{3xP3-RFP.attP}, M{vas-int.B} and P{nos-phiC31\int.NLS} insertions: Bischof et al. 2007 (see FlyC31 for additional information the phiC31 integrase system)

M{vas-int.Dm} insertions: K. Basler and F. Karch, FlyC31

P{attP.w[+].attP} insertions for Recombinase-Mediated Cassette Exchange (RMCE): Bateman & Wu, 2008, Sun et al., 2012

Position effects of attP sites on transgene expression: Markstein et al. 2008, Nature Genetics 40, 476 - 483.