Basic HTML Version
Poster Full Abstracts - Systems and Quantitative Biology
Poster board number is above title. The first author is the presenter
366
The wing of the fruit fly, Drosophila melanogaster, with its simple, two-dimensional structure, is a model organ well suited for a systems biology
approach. The wing arises from an epithelial sac referred to as the wing imaginal disc, which undergoes a phase of massive growth and concomitant
patterning during larval stages. The Decapentaplegic (Dpp) morphogen plays a central role in wing formation with its ability to co-ordinately regulate
patterning and growth. Here, we asked whether the Dpp signalling activity scales, i.e. expands proportionally, with the growing wing imaginal disc. Using
new methods for spatial and temporal quantification of Dpp activity and its scaling properties, we found that the Dpp response scales with the size of the
growing tissue. Notably, scaling is not perfect at all positions in the field and the scaling of target gene domains is ensured specifically where they define
vein positions. We also found that the target gene domains are not defined at constant concentration thresholds of the downstream Dpp activity gradients P-
Mad and Brinker. Most interestingly, Pentagone, an important secreted feedback regulator of the pathway, plays a central role in scaling and acts as an
expander of the Dpp gradient during disc growth.
879C
Screening for recessive suppressors of ectopic Wnt/Wg signaling in the Drosophila eye.
Fabian H. Jenny
1,2
, Monika Hediger Niessen
1
, Carla Baenziger
1
,
Corinna Schuett
1
, Luca Mariotta
1
, Konrad Basler
1
. 1) Institute of Molecular Life Sciences, University of Zurich, Zurich, Zurich, Switzerland; 2) Zurich
Ph.D. Program in Molecular Life Sciences, Life Science Zurich, Zurich, Zurich, Switzerland.
In the past, several screens for dominant Wnt/Wg signaling components were performed leading to the identification of a number of key components.
Since only few recessive screens were performed, we initiated EMS screens for recessive components on chromosome arms 3L and 3R. In the first screen on
chromosome arm 3L we used a sev-wg construct to ectopically expression wg and on the 3R screen a sev>y+>wg flpout cassette, which increased the lines
viability significantly. Both setups, the latter one in combination with eyeless induced Flippase, lead to a small/rough eye phenotype. Mutagenized animals
were screened for suppression of this phenotype and several candidate lines could be established. On 3L candidates were mapped conventionally with
recombination mapping. This led to the discovery of wntless, an important factor in Wg secretion. On 3R nine of 32 candidates are being mapped with a
whole-genome re-sequencing (WGS) approach. The gene identification and analysis is ongoing.
880A
The Genetic Basis for Natural Variation in Alcohol Sensitivity in Drosophila.
Tatiana V. Morozova
1,3
, Michael M. Magwire
2,3
, Trudy F.C. Mackay
2,3
,
Robert R.H. Anholt
1,2,3
. 1) Dept. Biology; 2) Dept. Genetics; 3) M. W. Keck Center for Behavior Biology, NCSU, Raleigh, NC.
Alcohol abuse and alcoholism are significant public health problems, but attempts to elucidate genetic risk factors in human populations have been
hampered by difficulties in quantifying alcohol-related phenotypes; obtaining large sample sizes; co-morbidity of alcoholism with other neuropsychiatric
disorders; and population admixture.
Drosophila melanogaster
presents a powerful model system to dissect the genetic underpinnings for alcohol related
phenotypes from which evolutionarily conserved aspects can be extrapolated to human populations. We used 167 wild-derived inbred lines of the Drosophila
Genetic Reference Panel (DGRP) to measure alcohol sensitivity and induction of tolerance. Genome-wide association (GWA) analyses identified
polymorphisms associated with both phenotypes. In parallel, we made reciprocal crosses of two DGRP lines that were extremely sensitive or resistant to
ethanol, assessed alcohol sensitivity in the F2, and retained the 10% most sensitive and resistant males and females for QTL mapping. We developed 96
evenly spaced SNP markers for single fly Illumina genotyping to map QTLs affecting ethanol sensitivity using composite interval mapping. We detected
several sex-specific QTLs on the X chromosome and chromosome 3R. These regions encompass genes with SNPs associated with alcohol sensitivity
identified by the GWAS study. These candidate genes can be verified further with mutational analysis or targeted gene disruption through RNAi knock-
down. Supported by NIH grants AA016560 and GM045146.
881B
Direct Quantification of Transcriptional Regulation at the Single Gene Level.
Heng Xu, Anna Sokac, Ido Golding. Biochemistry and Molecular
Biology, Baylor College of Medicine, Houston, TX.
Recent advances in RNA labeling and imaging techniques have enabled the precise quantification of transcription kinetics at a single gene locus, in both
live and fixed samples. However, it has not been possible to directly relate the observed kinetics with their causative events, namely the binding of
transcription factors at the gene’s regulatory region. We are currently developing a fluorescence-based method aimed at simultaneously measuring the
number of transcription factors bound at the vicinity of a gene and the resulting mRNA synthesis, both at the level of an individual gene copy in a single
nucleus. The method combines high-resolution fluorescence confocal microscopy, automated image segmentation and statistical analysis of multiple
stochastic events. We have begun to apply our new method to the study of hunchback (
hb
) transcriptional regulation by multiple transcription factors during
early embryo development.
882C
Phenotypic Plasticity of the Drosophila Transcriptome.
Shanshan Zhou, Terry Campbell, Eric Stone, Trudy Mackay, Robert Anhot. Dept Biology, North
Carolina State Univ, Raleigh, NC.
Phenotypic plasticity is the ability of a single genotype to produce different phenotypes in response to changing environments. We assessed variation in
genome-wide gene expression and four fitness-related phenotypes of an outbred Drosophila melanogaster population under 20 different physiological,
social, nutritional, chemical and physical environments, and compared the phenotypically plastic transcripts to genetically variable transcripts in a single
environment. The environmentally sensitive transcriptome consists of two transcript categories, which comprise ~15% of expressed transcripts. Class I
transcripts are genetically variable and associated with detoxification, metabolism, proteolysis, heat shock proteins, and transcriptional regulation. Class II
transcripts have low genetic variance, and show sexually dimorphic expression enriched for reproductive functions. Clustering analysis of Class I transcripts
reveal a fragmented modular organization, and distinct environmentally-responsive transcriptional signatures for the four fitness-related traits. Our analysis
suggests that a restricted environmentally-responsive segment of the transcriptome preserves the balance between phenotypic plasticity and environmental
canalization.
883A