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Poster Full Abstracts - Neurophysiology and Behavior
Poster board number is above title. The first author is the presenter
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address these questions due to its relative neuronal simplicity and increasingly sophisticated genetic tools. Nevertheless, the lack of a reliable and accurate
gait analysis method limits insights into the circuits and mechanisms that regulate coordinated walking. In order to address this challenge, we developed an
optical method coupled with high-speed imaging that allows us to unambiguously identify footprints and simultaneously track the fly’s body as it walks
freely on a flat surface. A custom analysis software allows us to track and quantify many parameters exhibited by walking flies, such as step timings,
footprint positions and left-right coordination. With this method we have characterized the walking behavior of wild-type animals and begun to carry out
loss and gain of function studies in a subset of leg sensory neurons. For this, we established a combinatorial expression system to specifically manipulate
neuronal function in different regions of the adult leg and to target specific components of the sensory system. Our results reveal how the interaction
between the CPGs and the sensory system modify the walking behavior in fruit flies.
643A
Egg laying decisions in Drosophila depend on the size of the oviposition substrate and are consistent with optimal larval foraging strategies.
Nicholas U Schwartz
1
, Lixian Zhong
2
, Andrew Bellemer
3
, W. Daniel Tracey
1,2,3,4,5
. 1) Neuroscience Program, Duke University, Durham, NC; 2)
Pharmacology Science Training Program, Duke University Medical Center, Durham, NC; 3) Department of Anesthesiology, Duke University Medical
Center, Durham, NC; 4) Department of Cell Biology, Duke University Medical Center, Durham, NC; 5) Department of Neurobiology, Duke University
Medical Center, Durham, NC.
Decision-making is defined as selection amongst options based on their utility, in a flexible and context-dependent manner. Oviposition site selection by
the female fly, Drosophila melanogaster, has been suggested to be a simple and genetically tractable model for understanding the biological mechanisms that
implement decisions. Here we show that egg-laying behavior in female Drosophila is sensitive to the potential foraging success of larval offspring in
different environments. With larger experimental substrates, females preferred to lay eggs directly on sugar containing media over other media. This was in
contrast to smaller substrates with closely spaced choices where females preferred non-sweetened media. However, the avoidance of sucrose on the smaller
substrates occurred only when a diffusion gradient from the sugar source was present. In the absence of diffusion, sugar was always preferred. Since a
diffusion gradient can be used by the larval progeny to locate the sucrose food on smaller substrates, we propose that the female choices have evolved to be
consistent with the search capabilities of their larval progeny. This represents evidence for egg-laying choices of female Drosophila that may relate to
optimal foraging strategies. Our findings offer a powerful model for the biology of decision-making. We propose that egg laying strategies may comply with
the marginal value theorem when viewed from the perspective of the larval progeny.
644B
The "secondary cells" of the D. malanogaster male accessory gland make products that prolong the female's post mating response.
Jessica L Sitnik
1
,
Dragan Gligorov
2
, Robert K Maeda
2
, François Karch
2
, Mariana Wolfner
1
. 1) Molecular Biology and Genetics, Cornell, Ithaca, NY; 2) Department of
Genetics & Evolution and NCCR Frontiers in Genetics, University of Geneva, Geneva, Switzerland.
In
Drosophila melanogaster
, products of the accessory gland (AG) of the male reproductive tract are essential for initiating and maintaining the female
postmating response (PMR) including changes in egg laying, receptivity to courting males, and sperm storage. All of these changes have been shown to be
mediated by the receipt of accessory gland proteins "ACPs" from her mate. The two lobes of the AG are composed of two major cell types that are
morphologically and biochemically distinct: the flat, hexagonally-shaped main cells which make up 96% of the gland and the large, spherical, vacuole-filled
secondary cells that are dispersed at the distal tip. While studies have determined that the main cells of the AG are necessary for these processes, no tools
were available to explore the role of the secondary cells. An enhancer deletion identified in the Hox gene
Abdominal-B (Abd-B)
,
iab-6
cocu
, results in a
morphologically uniform AG that lacks large vacuole filled secondary cells. By testing the impacts of the
iab-6
deletion on female post mating response, we
determined that products of the secondary cells are required for long-term changes in egg laying and receptivity in post-mated females, and are influential
during sperm competition. Further, the secondary cells contribute to regulating the glycosylation of at least three Acps; ovulin (Acp26Aa), CG1656, and
CG1652. Our results show that the secondary cells play an essential role in male fertility, likely through affecting the storage and gradual release of sex
peptide. To identify secondary cell products necessary for the PMR, we have used RNA-seq to identify genes whose expression is down regulated in
iab-
6
cocu
mutants. Using a secondary cell-specific driver derived from our enhancer mutant, we are driving RNAi in these cells to test our candidate genes for
roles in regulating the PMR.
645C
Identification of interneurons involved in Drosophila larval reactions to distinct somatosensory stimuli.
Marta Zlatic, Tomoko Ohyama, Tihana
Jovanic. HHMI Janelia Farm Research Campus, Ashburn, VA.
The principles by which sensory information is processed and used to generate motor responses by the underlying neural circuits are still poorly
understood. Most neural circuits are composed of large numbers of interconnected neuron classes and the roles of most of the neuron classes in most circuits
are poorly understood. We use the somatosensory circuitry of Drosophila larvae to study the role of distinct neuron classes in sensorimotor transformations.
This system offers numerous advantages. All somatosensory neurons and motor neurons have been anatomically identified and are known to project to the
ventral nerve cord (VNC). The VNC contains a relatively small number of interneuron classes (several hundred), and the Truman lab at Janelia HHMI has
identified a GAL4 line for a large number of these (generated by the Rubin lab). Thus, the basic sensorimotor pathways are genetically tractable and a
variety of genetic tools can be applied to test the contributions of individual neuron classes in reactions to sensory stimuli. We have developed a platform for
high-throughput and high-resolution analysis of larval reactions to a number of distinct somatosensory stimuli including pain, vibration and air currents.
Using this system, we found that each stimulus induces not just a single action, but a stereotyped and characteristic sequence of actions. We used Rubin
GAL4 lines to identify sensory and interneuron classes required and sufficient for various aspects of larval reactions to pain, vibration and air currents. We
are currently performing calcium imaging experiments to further characterize the roles of identified interneurons in these somatosensory guided behaviors.
646A
Neural representations of courtship song in the
Drosophila
brain.
Philip Coen
1
, Sina Tootoonian
2,3
, Mala Murthy
1
. 1) Molecular Biology and Princeton
Neuroscience Institute, Princeton University, Princeton, NJ; 2) Computation and Neural Systems Program and Division of Biology, California Institute of