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Poster Full Abstracts - Systems and Quantitative Biology
Poster board number is above title. The first author is the presenter
365
mutations that have synergistic interactions in tumorigenesis and explore the potential of using cooperative mutational patterns as diagnostic and prognostic
biomarkers for cancer.
875B
Region-specific interpretation of MAPK signaling in the
Drosophila
embryo.
Yoosik Kim
1
, Antonina Iagovitina
1,2
, Dimitri Papatsenko
3
, Keisuke
Ishihara
1
, Kate M. Fitzgerald
1
, Bart Deplancke
2
, Stanislav Y. Shvartsman
1
. 1) Department of Chemical and Biological Engineering and Lewis-Sigler
Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; 2) Ecole Polytechnique Fédérale de Lausanne, School of Life Sciences,
Institute of Bioengineering, Station 15, 1015 Lausanne, Switzerland; 3) Department of Developmental and Regenerative Biology, Black Family Stem Cell
Institute, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029-6574, USA.
Terminal regions of
Drosophila
embryo are patterned by the highly conserved Mitogen Activated Protein Kinase (MAPK) pathway which induces several
genes, relieving their repression by Capicua, a uniformly distributed repressor. The levels of activation signal for the pathway at the anterior and posterior
poles of the embryo are essentially the same. Yet, the expression patterns of most of genes induced MAPK signaling at the termini display a pronounced
anterior-posterior asymmetry. We present an experimentally based theory that can explain this asymmetry in the expression domains of
tailless
(
tll)
and
huckebein
(
hkb
), the two genes essential for the terminal patterning. The expression patterns of
tll
and
hkb
overlap at the posterior pole, with the expression
domain of
hkb
fully covered by a broader domain of
tll
. In contrast, the expression domains of these two genes do not overlap at the anterior pole. We
propose that this asymmetry is generated by a complex mechanism that involves multiple graded signals, an incoherent feedforward loop, and multiple
enhancers. Based on this mechanism, we can explain the wild-type expression patterns of
tll
and
hkb
and their changes induced by variations in the
distribution of the Bicoid, Dorsal, and MAPK activation gradients.
876C
Natural Variation in Olfactory Discrimination in the Drosophila Genetic Reference Panel.
Gunjan H. Arya
1,2
, Michael M. Magwire
2,3
, Yazmin L.
Serrano Negron
1,2
, Trudy F. C. Mackay
2,3
, Robert R. H. Anholt
1,2,3
. 1) Dept. of Biology, NC State Univ, Raleigh, NC; 2) W. M. Keck Ctr. for Behavioral
Biology, NC State Univ, Raleigh, NC; 3) Dept. of Genetics, NC State Univ, Raleigh, NC.
Most organisms depend on chemical signals for survival and reproduction. To gain insights in the genetic underpinnings of natural variation in olfactory
behavior we measured behavioral responses to 14 odorants in 168 lines of the Drosophila Genetic Reference Panel. Genetic variation among individuals
within each line is minimal, whereas genetic variation among the lines reflects the variation of the population from which they were derived. Whole genome
sequences have been obtained for these lines and 4,672,297 single nucleotide polymorphisms (SNPs) have been identified. We observed substantial variation
in olfactory behavior for all 14 odorants with broad sense heritabilities ranging from 0.11 to 0.35. Genome-wide association analysis identified 2,537 SNPs
associated with variation in olfactory behavior towards at least one odorant at a nominal
P
< 10
-5
. Polymorphisms associated with variation in responses to
different odorants do not necessarily reside in olfactory receptors (although some chemoreceptor transcripts are also implicated), but cover a range of gene
ontology categories, with apparent overrepresentation of genes associated with functions of the nervous system. Thus, variation in behavioral responses to
odorants depends on their perceptual integrated neural representations. Gene ontology analysis using R-Spider (www.bioprofiling.de) showed a network of
74 interconnected genes with overrepresentation of categories that include axon guidance, cell adhesion, intracellular signaling pathways, cytoskeletal
organization and EGFR signaling. In addition, a second network of four genes was centered on
Notch
. Thus, SNPs that give rise to subtle variations in neural
connectivity contribute to genetic variation in olfactory perception and individual differences in odor discrimination. Supported by NIH grants GM059469
and GM045146.
877A
Label-Free Imaging of Lipid-Droplet Intracellular Motion in Early Drosophila Embryos Using Femtosecond Stimulated Raman Loss Microscopy.
Wei Dou
1
, Delong Zhang
2
, Yookyung Jung
3
, Ji-Xin Cheng
2,3
, David Umulis
1,3
. 1) Department of Agricultural and Biological Engineering, Purdue
University, West Lafayette, IN; 2) Department of Chemistry, Purdue University, West Lafayette, IN; 3) Weldon School of Biomedical Engineering, Purdue
University, West Lafayette, IN.
Lipid droplets are complex organelles that exhibit highly dynamic behavior in early Drosophila embryo development. Imaging lipid droplet motion
provides a robust platform for the investigation of shuttling by kinesin and dynein motors, but current imaging methods are either destructive or deficient in
resolution and penetration to study large populations of droplets in an individual embryo. Here we report real time imaging and quantification of lipid-
droplet motion in live embryos using a newly developed technique termed femtosecond stimulated Raman loss microscopy (fSRL). To quantify intra-
embryonic lipid-droplet transport, we applied fSRL microscopy to image living Drosophila embryos from the syncytial blastoderm stage through early
gastrulation. Our results show that lipid droplets provide the major contrast captured by fSRL imaging of the embryo, which also provided higher resolution
and deeper penetration depth than other existing techniques. Furthermore, fSRL proved to be capable of long-duration, high-resolution imaging on the order
of hours to track the dynamic evolution of lipid droplets in vivo with minimal photo-damage to the embryos that proceed with normal development. Using
fSRL, time-lapse images of the embryo in vivo at both the organism and cellular levels were acquired, and quantitative analysis of lipid-droplet intracellular
motion by the tracking of single droplets shows both a time and space dependence for the speed and turning rate for droplet motion. Based on the tracking
results, we simulated droplet motion using a velocity-jump model. The model yielded droplet net distributions that agreed well with experimental
observations without any model optimization or unknown parameter estimation, demonstrating the sufficiency of a velocity-jump process for trafficking
dynamics of lipid droplets in early fly embryos.
878B
Dpp Signaling Activity Requires Pentagone to Scale with Tissue Size in the Growing Drosophila Wing Imaginal Disc.
Fisun Hamaratoglu
1
, Aitana
Morton de Lachapelle
2,3
, George Pyrowolakis
4,5
, Sven Bergmann
2,3
, Markus Affolter
1
. 1) Growth and Development, Biozentrum, University of Basel, Basel;
2) Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland; 3) Swiss Institute of Bioinformatics, Lausanne, Switzerland; 4) Institute
for Biology I, Albert-Ludwigs-University of Freiburg, D-79104 Freiburg, Germany; 5) Centre for Biological Signaling Studies (BIOSS), Albert-Ludwigs-
University of Freiburg, D-79104 Freiburg, Germany.