In this chapter we describe how one can use peripodial GAL4
drivers, UAS RNAi libraries, and the temperature-sensitive repressor, GAL80
ts , to screen for genes involved in the peripodial pEMT
using adult eversion phenotypes (Fig. 1). For genes with partially
penetrant phenotypes, screens for enhancer/suppressor genes can
Fig. 1 Overview. (a) Wandering third-instar larva with one wing disc highlighted. (b) A white prepupa which has
everted spiracles and ceased movement but not yet begun to tan. (c) Approximately 2–3 h later, the
attachment point at the stalk of the wing discs has moved laterally within the pupal case and the pEMT is
underway. (d) Approximately 5 days later an eclosed adult showing a single eversion failure, whereby one
wing disc is still internalized and half the thorax is missing. (e) Schematic of the stage when the PE cells of the
wing disc (green) undergo a pEMT, whereby they become motile and dismantle their epithelial junctions,
secrete MMPs to degrade the basement membrane (red), and invade through the overlying epidermis (gray).
(f) Wing discs can be isolated from larvae and cultured in the presence of ecdysone. (g) Wing disc at 0 h. (h)
After 7–8 h, the pEMT is underway and perforations in the peripodial epithelium (green) are forming and
expanding outwards (arrows). The DP cells are undergoing morphogenetic movements that bring the dorsal
and ventral halves of the wing blade together. Contractions in the cuboidal stripe cells flanking the squamous
central peripodial cells (not shown) cause the wing disc to bend [15]. (i) Leaving the disc for longer periods
results in a fully everted disc in which the PE has completely retracted over the DP cells and forms a clump,
while the wing blade has become more flattened and “wing-like”
Using Drosophila Wing Eversion to Study EMT
117
drivers, UAS RNAi libraries, and the temperature-sensitive repressor, GAL80
ts , to screen for genes involved in the peripodial pEMT
using adult eversion phenotypes (Fig. 1). For genes with partially
penetrant phenotypes, screens for enhancer/suppressor genes can
Fig. 1 Overview. (a) Wandering third-instar larva with one wing disc highlighted. (b) A white prepupa which has
everted spiracles and ceased movement but not yet begun to tan. (c) Approximately 2–3 h later, the
attachment point at the stalk of the wing discs has moved laterally within the pupal case and the pEMT is
underway. (d) Approximately 5 days later an eclosed adult showing a single eversion failure, whereby one
wing disc is still internalized and half the thorax is missing. (e) Schematic of the stage when the PE cells of the
wing disc (green) undergo a pEMT, whereby they become motile and dismantle their epithelial junctions,
secrete MMPs to degrade the basement membrane (red), and invade through the overlying epidermis (gray).
(f) Wing discs can be isolated from larvae and cultured in the presence of ecdysone. (g) Wing disc at 0 h. (h)
After 7–8 h, the pEMT is underway and perforations in the peripodial epithelium (green) are forming and
expanding outwards (arrows). The DP cells are undergoing morphogenetic movements that bring the dorsal
and ventral halves of the wing blade together. Contractions in the cuboidal stripe cells flanking the squamous
central peripodial cells (not shown) cause the wing disc to bend [15]. (i) Leaving the disc for longer periods
results in a fully everted disc in which the PE has completely retracted over the DP cells and forms a clump,
while the wing blade has become more flattened and “wing-like”
Using Drosophila Wing Eversion to Study EMT
117