Date

5-12-2011

UMMS Affiliation

Graduate School of Biomedical Sciences, MD/PhD Program; Graduate School of Biomedical Sciences, Program in Neuroscience

Document Type

Dissertation, Doctoral

Subjects

Drosophila melanogaster; Feeding Behavior; Neurons; Drosophila Proteins; TRPC Cation Channels; Dissertations, UMMS

Disciplines

Behavioral Neurobiology | Neuroscience and Neurobiology

Abstract

Feeding is one of the most important behaviors for an animal’s survival. At a gross level, it is known that the nervous system plays a major role in the expression of this complex behavior, yet a detailed understanding of the neural circuits directing feeding behavior remains unknown. Here we identify a command neuron in Drosophila melanogaster whose artificial activation, using dTrpA1, a heat-activated cation channel, induces the appearance of complete feeding behavior. We use behavioral, genetic, cellular and optical imaging techniques to show that the induced behavior is composed of multiple motor programs and can function to uptake exogenous, even noxious, material. Furthermore, we resolve the neuron’s location to the subesophageal ganglion, characterize its pre and post-synaptic sites, and determine its responsiveness to sucrose stimulation. Interestingly, the neuron’s dendritic field is proximal to sweet sensing axon terminals and its baseline activity corresponds to the fly’s satiation state, suggesting a potential point of integration between sensory, motor and motivational systems. The identification of a command neuron for feeding in a genetically tractable organism provides a useful model to develop a deeper understanding of the neural control of this ubiquitous and evolutionarily ancient behavior.

Comments

This dissertation includes 44 videos that are referenced in Chapters II and III. See Additional Files below.

Movie 2.1.mov (741 kB)
Wild-type behavior at 15°C.

Movie 2.2.mov (22313 kB)
Trpm8-induced ‘Full Paralysis’.

Movie 2.3.mov (21661 kB)
Trpm8-induced ‘Wing Beat Paralysis’.

Movie 2.4.mov (23021 kB)
Trpm8-induced ‘Frozen Still Paralysis’.

Movie 2.5.mov (1226 kB)
Trpm8-induced ‘Short Spasm’.

Movie 2.6.mov (2266 kB)
Trpm8-induced ‘Tipsy’.

Movie 2.7.mov (1831 kB)
Trpm8-induced ‘Wing Raising’.

Movie 2.8.mov (26934 kB)
Trpm8-induced ‘Wing Clip’.

Movie 2.9.mov (947 kB)
Trpm8-induced ‘Wing Beat’.

Movie 2.10.mov (11325 kB)
Trpm8-induced ‘Aggression’.

Movie 2.11.mov (52068 kB)
Trpm8-induced ‘Courtship Song’.

Movie 2.12.mov (898 kB)
Trpm8-induced ‘Grooming’.

Movie 2.13.mov (3291 kB)
Trpm8-induced ‘Exploration’.

Movie 2.14.mov (2798 kB)
Trpm8-induced ‘Jumping’.

Movie 2.15.mov (186806 kB)
Trpm8-induced ‘Courtship’ at 25°C.

Movie 2.16.mov (2428 kB)
dTrpA1-induced ‘Wing Raise’.

Movie 2.17.mov (2416 kB)
dTrpA1-induced ‘Egg Laying’.

Movie 2.18.mov (297 kB)
dTrpA1-induced ‘Egg Laying’ part 2.

Movie 2.19.mov (25593 kB)
dTrpA1-induced ‘Abdominal Bending’.

Movie 2.20.mov (2028 kB)
dTrpA1-induced ‘Feeding’.

Movie 2.21.mov (1242 kB)
dTrpA1-induced ‘Feeding’ part 2.

Movie 2.22.mov (17840 kB)
dTrpA1-induced ‘Initiation of Voluntary Flight’.

Movie 2.23.mov (475 kB)
dTrpA1-induced ‘Initiation of Voluntary Flight’ part 2.

Movie 2.24.mov (535 kB)
dTrpA1-induced ‘Initiation of Voluntary Flight’ part 3.

Movie 2.25.mov (2137 kB)
dTrpA1-induced ‘Initiation of Voluntary Flight’ part 4.

Movie 2.26.mov (19619 kB)
dTrpA1-induced ‘Airplane’.

Movie 2.27.mov (21371 kB)
dTrpA1-induced ‘Backstroke’.

Movie 2.28.mov (12145 kB)
dTrpA1-induced ‘Crazy Leg Paralysis’.

Movie 2.29.mov (27144 kB)
dTrpA1-induced ‘Wing Raise/Aggression’.

Movie 2.30.mov (22918 kB)
dTrpA1-induced ‘Wing Raise/Aggression’ version 2.

Movie 3.1.mov (7325 kB)
Wild-type feeding behavior of starved fly on food.

Movie 3.2.mov (9763 kB)
dTrpA1-induced behavior closely resembles wild-type feeding behavior.

Movie 3.3.mov (1602 kB)
NP5137-GAL4/uas-dTrpA1 induced behavior resembles natural feeding.

Movie 3.4.mov (1407 kB)
Male NP-GAL4/uas-dTrpA1 flies display suction.

Movie 3.5.mov (1759 kB)
Cibarial pump is activated and functioning.

Movie 3.6.mov (1560 kB)
Behavior can be induced in unnatural contexts.

Movie 3.7.mov (3413 kB)
Mosaic FC-neuron positive flies demonstrate the induction of multiple motor programs characteristic of wild-type feeding behavior.

Movie 3.8.mov (5208 kB)
3-D movie of FC-neuron from mosaic fly showing predicted pre and post-synaptic compartments.

Movie 3.9.mov (6798 kB)
Proboscis extension behavior during simultaneous calcium imaging.

Movie 3.10.mov (1934 kB)
Flies expressing the kir2.1 channel appeared vigorous and healthy before testing.

Movie 3.11.mov (1377 kB)
Positive proboscis extension (PE).

Movie 3.12.mov (22267 kB)
Visualization of cibarial pump activity in wild-type flies.

Movie 3.13.mov (3260 kB)
Dye Assay analysis at three points along the gastrointestinal tract.

Movie 3.14.mov (1259 kB)
Fly love.