DAM2 Drosophila Activity Monitor
The DAM2 Drosophila Activity
Monitor measures the locomotor
activity of 32 individual flies, each ina separate tube. As a fly walks backand forth within its tube, itinterrupts an infrared beam thatcrosses the tube at its midpoint,
and this interruption, detected by
the onboard electronics, is added tothe tube’s activity count as ameasure of fly activity.
In a typical experiment, an agar/
sucrose food mixture is placed into
one end of each tube, followed by
the fly, and followed by a cottonplug in the open end. The 32 tubes
are inserted into holes in themonitor case, and centered.

DAM2Features

Over the course of the experiment, which
may last for days or weeks, the counting
circuits continuously monitor the activity inall 32 tubes, and at periodic intervals upload
their count totals to the host computer forstorage and later analysis. This daily record
provides a good measure of both theintensity of locomotor activity and therelative periods of rest.

• 32 tubes for 32 flies• 5mm tube diameter for drosophilamelanogaster, 7mm for d. virilis• Consistent operation in bright room lightor darkness• Ambient light sensor provides on/oﬀ

record of entrainment cycles, stimulation
pulses, and inadvertent light exposure.

The DAM2 is fabricated from a transparent
polycarbonate plastic, allowing light
penetration to all points along the tube. It iscompact, light in weight, and when usedwithin an incubator, allows plentiful air
circulation around the tubes. The throughhole design accommodates tubes ofarbitrary length.

Specifications• Tube diameter: 5mm or 7mm• Tube length: 65mm nominal, transparent
glass or plastic• Dimensions: 127 x 48 x 87 mm LWH• Mass: 0.17 kg without tubes

An on/oﬀ visible light sensor is built into
each unit to provide a simple record of theambient light state over time. This record
accompanies the activity count data as it isacquired and stored, and is useful inanalyzing circadian rhythms and adaptationsof the flies to external light stimuli.

• Ambient Light Sensor threshold: 10 lux
nominal, photopic response curve• Interconnect: 4 wire, 6 position, RJ-11
modular telephone line jack to PSIU9DAMSystem network for 9V DC powerinput and data transmission

An optional gas distribution manifold isavailable to facilitate the controlled exchangeof air within the tubes, as would be needed
for hypoxia studies.

• Operating environment: normallaboratory, non-condensing

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TubesWe supply tubes in Corning Pyrex glass (5 or 7mm diameter by 65mm length) andpolycarbonate plastic (5mm diameter by 65mm length.) Both materials are transparent, andmay be washed and autoclaved for cleanliness and sterility.

Fly FoodA food mixture must be placed into one end of each tube to sustain the fly over the course ofa multi-day experiment. Many recipes are reported in the literature, but a simple one whichworks is as follows:
100 ml water
5g sucrose crystals
2g agar powder
Combine the ingredients in a glass beaker, and bring carefully to a boil using a hot plate or
microwave oven. When the solids are completely dissolved, pour the solution slowly down theside of another glass beaker containing the glass tubes standing on end, to a level of about
15mm deep. Allow the mixture to cool and solidify. Carefully remove the tubes from the agar
matrix, sealing the tops with a finger to retain the food, and wipe them clean. Then seal thefood end of each tube with either a quick dip in melted paraﬃn wax or a plastic cap to prevent
desiccation. The flies may now be loaded, one into the open end of each tube, and the tubes
then plugged with cotton.

Monitor Setup
Tubes containing flies must be the proper diameter, and may have a wax coating or plastic
cap on one end to seal the fly food. Insert the tubes through the 32 holes in the monitor, andleave them centered so that the detection beam will bisect the tube.
If captivation of the tubes is necessary to prevent sliding, use rubber bands, stretched firstover the 4 corner tubes of 2 adjacent rows, and pressed up against the monitor surface. Thenremove the tubes from columns 3 and 6, and reinsert them from above and below the bands asshown to place them into frictional contact.

Tube restraint

With the tubes installed, the monitor may be plugged into the DAMSystem network.

Ambient Light Sensor
Each unit contains an ambient light sensor, which may be seen adjacent to the hole for tube
#1. This sensor is set to discriminate light from dark at a nominal threshold of 10 lux, and willreport its output with the count data at each collection bin. With the Monitor tab set to Live or
Current and #nnn, the sensor output will be displayed in real time, and may be used for
diagnostic purposes. When File data is retrieved from the monitor at the end of each bin, thelight sensor will report dark(0) only if dark for the entire preceding bin. If the sensor measures
light above its threshold at any point during the bin, it will report light(1) for the bin, serving todetect door openings or other lights-on transients.
The sensor output is reported in column 10 of the MonitorNNN file.

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Data Collection
To verify that the monitor is operating properly, click Current Data and Monitor NN in theDisplay Selector of DAMSystem3, and then click NN up or down to choose the monitor numberin question. The status box should be green (status 1), and the 32 channels of real-time countactivity should be displayed. If a thin object such as a pencil point is moved through one of thetube cavities, the count total for that channel should increment.
The monitor will accumulate activity counts for as long as it has operating power, and will
uplink its accumulated counts (and then reset to 0) whenever commanded to do so by the hostcomputer. Counts will be accumulated as the flies are active in both total darkness and brightambient light.

Precautions
The light detectors used in the counting beams are sensitive to ambient light in the infraredband, as would be emitted from a hot incandescent bulb. Such external light will normally notprevent the counting circuits from detecting fly movement, but may cause false counts if thelevel of such light changes rapidly (as when the light turns on or oﬀ, or is shadowed.)
Fluorescent or LED lights, emitting principally in the visible band, will not cause such transientcounts.
The DAM2 is vulnerable to corrosion damage if water penetrates its case while operating.
Beware incubator condensation drips, and if standing water is detected, dry the unit
immediately in a warm oven.

MAN2 Gas Distribution Manifold
This accessory for the DAM2 provides
controlled gas flow to the flies, allowing
studies of drug and alcohol interaction
and hypoxia. A common inlet port andmanifold cavity distributes the gas toeach tube, and small exit holes near their
far end allow gases to escape, but not
the flies.
A silicone rubber gasket seals eachtube exit, and stainless-steel meshprevents flies from exiting into themanifold cavity.
The manifold body is PVC plastic,
making it robust to chemical attack, andthe entire unit may be disassembled forcleaning.

DAM2 + MAN2Two manifolds, one on either end of thetubes, would provide a sealed system, preventing gas escape to the environment.
The inlet tube fitting accepts 3/16” ID flexible tubing.

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