Visualization of the Transport of Individual dpp Particles in Drosophila during Embryonic
Development by Binding to Quantum Dots
Joshua Cheng & Michelle Ding
Mentor: Arthur Lander
Morphogens are biochemicals able to direct specific patterns of cell differentiation during early
development. Applied along a gradient, any cell in the developing embryo undergoes differentiation
appropriate to its position along both the dorsoventral and anteroposterior axes. Decapentaplegic
(dpp) in Drosophila, as a member of the Transforming Growth Factor β (TGF β) family, is functionally
analogous to morphogens Squint, Activin, and BMP-2 in Zebrafish, Xenopus, and humans,
respectively. While dpp activity had been extensively studied, the exact mechanism of its transport to
act directly on the embryonic Drosophila cells is still unclear. We attempt to track dpp movement by
using Quantum Dots. The gene for a dpp fused with acceptor peptide (AP) for biotin was produced
in E. coli and, through the Gateway System, successfully introduced and expressed in S2 cells.
Likewise, both an endogenous and secreted biotin ligase were also expressed in S2. Future
coexpression will yield in vivo biotinylated dpp, which can then be bound to Quantum Dots and
injected into the perivitelline space of Drosophila embryos. This way we can enable visualization of dpp
and investigate its positive feedback transport mechanism.