Mushroom Body is a Quadruple Structure

Mushroom Body is a Quadruple Structure - Figure 2

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The mechanism of the FRT-GAL4 clone labelling system
(combination of flp / FRT and GAL4 / UAS systems)

To reveal the cytoplasmic structures of the clonally related cells made by each neuroblast, we developed a new clone-labelling method that combines the yeast flp / FRT system (Golic and Lindquist, 1989; Struhl and Basler, 1993) with the GAL4 / UAS system (Brand and Perrimon, 1993). The central component is called AyGAL4, which is a cytoplasmic Actin promoter - GAL4 fusion gene that is made non-functional by the insertion of transcriptional termination signals.

(A) In the initial state, transcription from the ubiquitous Actin promoter in AyGAL4 is terminated at the hsp70 transcriptional termination signal.

(B) Upon heat shock, the hsp70 promoter drives the flp gene that encodes Flippase recombinase. The Flippase protein catalyses recombination at the two FRT sequences of AyGAL4, and removes the termination signal as well as a marker gene, yellow.

(C) The GAL4 protein expressed from the rearranged Act5C promoter-GAL4 fusion gene activates transcription of the UAS-tau reporter gene. Thus, only the cells that experienced recombination, and their progeny, express the bovine Tau protein, which can be revealed using an anti-Tau monoclonal antibody. Since Tau is a microtubule-associated protein that is actively distributed throughout the cytoplasm via the slow transport mechanism, the whole cellular structure and the innervation pattern of the labelled cells can be resolved.

References

Brand, A. H., and Perrimon, N. (1993). Targeted gene expression as a means of altering cell fates and generating dominant phenotypes. Development 118, 401-415.

Golic, K. G., and Lindquist, S. (1989). The FLP recombinase of yeast catalyzes site-specific recombination in the Drosophila genome. Cell 59, 499-509.

Struhl, G., and Basler, K. (1993). Organizing activity of wingless protein in Drosophila. Cell 72, 527-540.

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Flybrain Development Mushroom Body Quadruple Structure Quadruple Structure - Figure 2

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