Automating fruit fly Drosophila embryo injection for high throughput transgenic studies

Abstract

To decipher and manipulate the 14 000 identified Drosophila genes, there is a need to inject a large number of embryos with transgenes. We have developed an automated instrument for high throughput injection of Drosophila embryos. It was built on an inverted microscope, equipped with a motorized xy stage, autofocus, a charge coupled device camera, and an injection needle mounted on a high speed vertical stage. A novel, micromachined embryo alignment device was developed to facilitate the arrangement of a large number of eggs. The control system included intelligent and dynamic imaging and analysis software and an embryo injection algorithm imitating a human operator. Once the injection needle and embryo slide are loaded, the software automatically images and characterizes each embryo and subsequently injects DNA into all suitable embryos. The ability to program needle flushing and monitor needle status after each injection ensures reliable delivery of biomaterials. Using this instrument, we performed a set of transformation injection experiments. The robot achieved injection speeds and transformation efficiencies comparable to those of a skilled human injector. Because it can be programed to allow injection at various locations in the embryo, such as the anterior pole or along the dorsal or ventral axes, this system is also suitable for injection of general biochemicals, including drugs and RNAi.

Microsystems for controlled genetic perturbation of live Drosophila embryos: RNA interference, development robustness and drug screening

“…The overall efficiency of injection is measured by the percentage of transformed embryos. After optimization, it was found that the overall injection efficiency using the robotic system was 50-75% that of manual injection with a rate of 60 embryos in 8 min (Cornell et al 2008). Although the injection speed and efficiency is comparable to manual injection, further optimization of this automated embryo Fig.…”

“…However, transgenic fruit flies are produced by injecting DNA into the posterior tip of the embryo. Recently, Cornell et al developed an automated microinjector system that injects embryos horizontally (Cornell et al 2008). This allows for the ability to penetrate an embryo at the poles as well as on the sides (Fig.…”

“…The alignment jig, however, lacks the flexibility to pre-screening the embryos in vivo to ensure that they are at the right stage in development. In addition, the adjustment of embryo orientations is limited comparing to that of a self-assembly pad (Cornell et al 2008). Both drawbacks can be overcome by staging the development of embryos properly prior to the injection process and modifying the system to inject at both ends of the embryo.…”

“…The system successfully injected embryos at a rate of 60 embryos in 8 min. The image sequence shows an injection process using the automated system (Cornell et al 2008) microinjection system is warranted to achieve injections with higher throughput and increased efficiency.…”

Towards ultrahigh throughput microinjection: MEMS-based massively-parallelized mechanoporation

“…Recent efforts to automate the microinjection process by replacing the operator with robotics have shown promise for improving success rates [3–6]; however, this has come at the expense of instrument complexity. Moreover, only modest gains in throughput have been achieved (≤35 cells/min).…”