Basic HTML Version
Poster Full Abstracts - Systems and Quantitative Biology
Poster board number is above title. The first author is the presenter
364
(sensitive/resistant) in
Drosophila melanogaster
genes based on orthologous genes with known anesthesia response in
Caenorhabditis elegans
, and vice
versa. Preliminary results (after assaying seven genes in fly based on known response in worm) are mixed, with four accurate and three incorrect predictions.
However, there are approximately 20 genes to be assayed between the two species, and the results after assaying all of them will be presented at the Fly
Meeting.
871A
Vibration-sensing circuitry of Drosophila larva with synaptic resolution.
Albert Cardona
1,2
, Casey Schneider-Mizell
2
. 1) HHMI Janelia Farm, Ashburn,
VA; 2) Institute of Neuroinformatics, University of Zurich and ETH Zurich, Switzerland.
The ventral nerve cord (VNC) of Drosophila larva contains central pattern generating circuits that underlie locomotion, and receives afferent axons from
somatosensory neurons. With a reduced number of neurons, the VNC offers us a uniquely approachable model system of somatosensory information
processing and motor control. The arbors of sensory neurons that project into a VNC segment, and of its motorneurons, have been characterized with light
microscopy (Merritt and Whitington, 1995; Landgraf et al., 1997). Interneurons are largely unknown. Here, we present the neuronal circuitry downstream of
the 8+8 chordotonal vibration-sensing sensory neurons of one abdominal segment of first instar, with their 468 interneuronal synaptic partners. We
reconstructed the circuitry from an electron microscopy volume that includes a little over one entire abdominal segment of a first instar larva. We used the
software TrakEM2 to skeletonize all neurons of interest and annotate their synapses. We analyzed the network and found a subset of interneurons that accrue
the lionshare of input from the chordotonals. About half of these interneurons are highly connected and constitute a segmental sensory integration module
with clear inputs from the dorsal motor neuropils, and from across the midline.
872B
The Rabome of
Drosophila melanogaster
.
Sebastian Dunst, Marko Brankatschk, Andreas Sagner, Beate Brankatschk, Marie Hannusa, Tom Kazimiers,
Pavel Tomancak, Suzanne Eaton. MPI-CBG, Dresden, Germany.
Rab family GTPases are major regulators of intracellular membrane trafficking. Disruption of Rab-mediated transport is implicated in several inherited
human disorders. The
Drosophila
genome encodes 23 Rab proteins with clear vertebrate homologues. However, no functions have been as yet ascribed to
the majority of Rab family members. Here, we present a novel resource to elucidate the role of each individual Rab protein for intracellular vesicle
trafficking. Generated by homologous recombination, our Rab library allows profound
in vivo
studies on endogenous expression levels and various knock-
down approaches. We systematically profiled and annotated a complete set of
rab
alleles harboring EYFP fusions at the endogenous loci in a tissue-wide
manner including larval salivary gland, wing imaginal disc, gut, fat body and brain. In these tissues, we examined their subcellular localizations and protein
amounts by quantitative PCR, high-resolution fluorescence microscopy and quantitative Western blotting. We see not only complete tissue specificity of
some Rabs, but also differences in quantitative levels and localization. We predict that these differences contribute to the differentiated function of tissues.
We further generate a publicly accessible online database that serves as a platform to share our data among the
Drosophila
community. To understand
functional requirements for each Rab protein, we are depleting them in a tissue- and time-specific manner by 3 methods: (i) by excision of rescuing
transgenes in null mutant backgrounds, (ii) by RNAi targeted against the EGFP tag and (iii) by cleavage of Rabs engineered to contain a TEV protease
cleavage site. We will demonstrate how our Rab protein library can be utilized for biochemical and genetic screens intended to identify cargo and additional
regulatory components of intracellular compartment classes. The comparison of payload dependent trafficking routes in different cell types during
Drosophila
development will shed light on the formation and function of specialized tissues.
873C
Knockdown of bicoid interrogates models for combinatorial control of gene expression.
Max V. Staller, Zeba Wunderlich, Meghan D. Bragdon, Kelly
B. Eckenrode. Dept Systems Biology, Harvard Medical School, Boston, MA.
In animals, cis-regulatory elements integrate information from multiple bound transcription factors to control target gene expression. The Drosophila
anterior/posterior patterning network offers a uniquely well characterized system for studying combinatorial control of gene expression. Genetic
perturbations helped uncover the topology of this network, yet each connection was identified in isolation and we lack an quantitative understanding of how
inputs work together to pattern outputs. The gap genes take input from maternal cues and extensively cross regulate each other; by removing one maternal
input we can quantify this cross regulation in a perturbed embryo. We took advantage of a new shRNAi system to knock down bicoid in blastoderm
embryos. We quantitatively measured the expression patterns of relevant gap genes and pair rules genes at cellular resolution by in situ hybridization and
two photon microscopy. Using established methods, we combined data from many embryos into a computationally amenable gene expression atlas, enabling
us to compare average expression of our selected genes in each cell. This atlas captures both primary and secondary effects of bicoid knockdown, enabling
us to disentangle direct from indirect effects. We use these data to test simple mathematical models that accurately predict expression in wild type for their
ability to predict perturbed patterns. Specifically, we compare the performance of models that assume independent contributions from each input
transcription factor with those that include interactions between inputs. We discuss how quantitative measurement of gene regulatory networks in perturbed
embryos can refine our understanding of how patterning informations flows through these networks and their component cis-regulatory functions.
874A
Systematic Characterization of Genetic Interactions in Tumorigenesis using Combinatorial RNAi in Drosophila Melanogaster.
Xiaoyue Wang,
Jennifer Moran, Kevin White. Institute for Genomics and Systems Biology, University of Chicago, Chicago, IL.
Tumorigenesis is a multi-step process driven by the accumulation of a series of genetic mutations in normal cells. Recently a tremendous amount of
genetic alterations in tumors have been uncovered owing to the advances in high-throughput genomics technologies. However, it is still challenging to
identify the “driver” mutations and understand how those mutations act jointly to define the course of cancer development. We plan to use combinatorial
RNAi in Drosophila Melanogaster to characterize genetic interactions between potential cancer genes. We have developed a system to generate multiple
gene knockdowns in flies in a high-throughput manner. We have also identified hundreds of combinations of genes that co-occur in tumors from cancer
genome sequencing data as candidate gene pairs to test for interactions. We are now testing genetic interactions by comparing the observed phenotypic
effects of combinatorial RNAi of two genes with the predicted effects based on their respective single-RNAi effects. We will further characterize the