The FRT cassette containing the GFP-tagged His3.3A coding region has been excised, allowing expression of the mKO-tagged His3.3A coding region under the control of UASp regulatory sequences.
In the absence of Scer\FRT, the T:Avic\GFP-tagged His3.3A coding region in P{UASp(FRT.His3.3A-GFP)His3.3A-mKO} is expressed under the control of the UASp sequences and there is little expression of the T:Zzzz\KOmKO-tagged His3.3A coding region which is downstream of the Scer\FRT cassette. In the presence of Scer\FRT, the Scer\FRT cassette containing the T:Avic\GFP-tagged His3.3A coding region is excised, allowing expression of the T:Zzzz\KOmKO-tagged His3.3A coding region under the control of the UASp sequences. This dual-colour method can be used to differentially label "old" versus "new" histones in cells.
In the absence of Scer\FRT, the T:Avic\GFP-tagged His3.3A coding region in P{UASp(FRT.His3.3A-GFP)His3.3A-mKO} is expressed under the control of the UASp sequences and there is little expression of the T:Zzzz\KOmKO-tagged His3.3A coding region which is downstream of the Scer\FRT cassette. In the presence of Scer\FRT, the Scer\FRT cassette containing the T:Avic\GFP-tagged His3.3A coding region is excised, allowing expression of the T:Zzzz\KOmKO-tagged His3.3A coding region under the control of the UASp sequences. This dual-colour method can be used to differentially label "old" versus "new" histones in cells.