Harvesting and Preparing &lt;em&gt;Drosophila&lt;/em&gt; Embryos for Electrophysiological Recording and Other Procedures

David E Featherstone,Kaiyun Chen,Kendal Broadie

doi:10.3791/1347

Abstract

Drosophila is a premier genetic model for the study of both embryonic development and functional neuroscience. Traditionally, these fields are quite isolated from each other, with largely independent histories and scientific communities. However, the interface between these usually disparate fields is the developmental programs underlying acquisition of functional electrical signaling properties and differentiation of functional chemical synapses during the final phases of neural circuit formation. This interface is a critically important area for investigation. In Drosophila, these phases of functional development occur during a period of <8 hours (at 25°C) during the last third of embryogenesis. This late developmental period was long considered intractable to investigation owing to the deposition of a tough, impermeable epidermal cuticle. A breakthrough advance was the application of water-polymerizing surgical glue that can be locally applied to the cuticle to enable controlled dissection of late-stage embryos. With a dorsal longitudinal incision, the embryo can be laid flat, exposing the ventral nerve cord and body wall musculature to experimental investigation. This system has been heavily used to isolate and characterize genetic mutants that impair embryonic synapse formation, and thus reveal the molecular mechanisms governing the specification and differentiation of synapse connections and functional synaptic signaling properties.

Highlights

Drosophila is a premier genetic model for the study of both embryonic development and functional neuroscience
A breakthrough advance was the application of water-polymerizing surgical glue that can be locally applied to the cuticle to enable controlled dissection of late-stage embryos
Two types of solutions are commonly used to bath the embryonic tissues during dissection: 1) “standard” (Jan and Jan, 1976a) or “modified standard” (Broadie, 2000) salines, based on solutions commonly used for recording in other invertebrate systems, and 2) “haemolymph-like” (HL) salines (Stewart et al 1994), a compromise between the standard saline and the ionic concentrations measured in the Drosophila haemolymph

Summary

Part 1: Equipment and Supplies

3. Equipment to make and modify fine glass needles is required. Pulled-glass needles are required for the dissection. Hollow glass needles (formed similar to patch clamp electrodes) are attached to plastic tubing and used during dissection for suction and expulsion of saline, as well as the controlled delivery of glue. A variety of glass pullers are available for manufacturing glass needles. 4. Two types of solutions are commonly used to bath the embryonic tissues during dissection: 1) “standard” (Jan and Jan, 1976a) or “modified standard” (Broadie, 2000) salines, based on solutions commonly used for recording in other invertebrate systems, and 2) “haemolymph-like” (HL) salines (Stewart et al 1994), a compromise between the standard saline and the ionic concentrations measured in the Drosophila haemolymph. Experimenters may want to consider commercially prepared insect saline (e.g. Schneider’s Insect Media), which is unsuitable for electrophysiological recording but most likely to protect the health of exposed tissues

Part 2: Embryo Staging and Dissection

Discussion