A Magnetic Tether System to Investigate Visual and Olfactory Mediated Flight Control in Drosophila

Summary

Here we describe how to tether a fly in an olfactory magnetic-tether (OMT) apparatus. We describe how to align the rare-earth magnets and odor ports, and how to set mass flow rates for both the stimulus delivery and vacuum suction to achieve optimal odor tracking.

Abstract

It has been clear for many years that insects use visual cues to stabilize their heading in a wind stream. Many animals track odors carried in the wind. As such, visual stabilization of upwind tracking directly aids in odor tracking. But do olfactory signals directly influence visual tracking behavior independently from wind cues? Also, the recent deluge of research on the neurophysiology and neurobehavioral genetics of olfaction in Drosophila has motivated ever more technically sophisticated and quantitative behavioral assays. Here, we modified a magnetic tether system originally devised for vision experiments by equipping the arena with narrow laminar flow odor plumes. A fly is glued to a small steel pin and suspended in a magnetic field that enables it to yaw freely. Small diameter food odor plumes are directed downward over the fly s head, eliciting stable tracking by a hungry fly. Here we focus on the critical mechanics of tethering, aligning the magnets, devising the odor plume, and confirming stable odor tracking.

Protocol

Introduction

The OMT is an adaptation of a magnetic tether system [1] designed to incorporate a “virtual plume simulator”. The following protocols will explain how to properly tether flies (Part 1) and provide strategies for setting up the magnets (Part 2) and mass-flow regulated odor delivery system (Part3). The information described here is optimized for this particular system and may vary for components with other technical specifications.

Part 1: Tethering flies

The steps for tethering described here are similar to many previous studies [2] but adapted for use in an OMT [3]. Proper tet....

Discussion

Tethering flies and eliciting stable odor tracking in this arena is relatively straightforward. It requires practice, patience and trial and error. Many parts of this arena could be further optimized or substituted to yield variations in experimental potential. For example, newer versions of the vacuum chamber are much smaller and allow more space below the arena. Also, the strength and type of rare-earth magnets can be varied slightly and additional odor ports could be added to increase the number of odor types and/or c.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Cooling Stage	Teca	LHP-300CP
Brass Cooling Block	Custom Made		~4 x 8 x 2cm
Sarcophagus	Custom Made		Contact us for details
UV-Activated Glue	Kemxert corp	KOA300	1oz bottle lasts years
Panel System	Caltech	http://www.dickinson.caltech.edu/panels	[4]
Minutien Pins	Fine Science Tools	26002-20
Lower Ring Magnets	Rare-earth-magnets.com	NSN0615	5 - 0.75"o.d. x 0.375" i.d. x 0.125"
Upper Rod Magnet	Rare-earth-magnets.com	NSN0750	0.125" x 1"
V-Jewel Bearing	Small Parts, Inc.	VJ-0469-01
MFC-4 Flow Regulators	Sable Systems International
Gas Multiplexer	Sable Systems International
Teflon Tubing	Small Parts, Inc.	STT-20-C
20 Gauge Hypodermic Tubes	Small Parts, Inc.	HTX-20R-06
Glass Tubing			4mm o.d.
Vacuum Flow Regulator	Cole-Parmer	EW-32464-52