Page 252 - 53rd Annual Drosophila Research Conference

Poster Full Abstracts - Drosophila Models of Human Diseases
Poster board number is above title. The first author is the presenter
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439A
Oxidative stress contributes to outcome severity in a Drosophila melanogaster model of classic galactosemia. Patricia P Jumbo-Lucioni1 , Marquise
Hopson1, Bill Liang2 , Dean Jones2 , Judith Fridovich-Keil1. 1) Dept. Human Genetics, Emory University School of Medicine, Atlanta, GA; 2) Pulmonary
Division, Dept. Medicine, Emory University School of Medicine, Atlanta, GA.
Classic galactosemia is a potentially lethal disorder that results from profound loss of galactose-1P-uridylyltransferase (GALT), the second enzyme in the
Leloir pathway of galactose metabolism. Despite decades of research, the pathogenic mechanism in galactosemia remains unclear. Previous publications
suggest an association between galactose exposure and free radical generation in genetically normal animal models. Our goal was to explore the impact of
dietary exposure to pro- or anti-oxidants on acute galactose-sensitivity using a GALT-deficient Drosophila melanogaster model of classic galactosemia. We
tested supplements based on their established or predicted roles as oxidants (paraquat and DMSO), anti-oxidants (α-mangostin and vitamin C), or
mitochondrial inhibitors (rotenone), and also tested additives that might bolster metabolism under conditions of mitochondrial dysfunction (uridine and
glutamine). To test the impact of each supplement, GALT-deficient and control flies were raised in parallel on foods with and without each supplement that
contained glucose as the sole sugar, or glucose plus galactose. Animals were scored for survival to pupation and adulthood. Our results showed that oxidants
had a deleterious impact on survival rates of GALT-deficient animals exposed to galactose, while antioxidants improved the survival of these animals
exposed to galactose. We saw little if any impact on GALT-deficient animals consuming glucose as the sole sugar, or wild-type animals regardless of sugar
exposure. As a biochemical measure of oxidative stress in these animals we measured oxidized (GSSH) and reduced (GSH) glutathione levels and found a
striking synergy between oxidant and galactose exposures. Combined, these results implicate oxidative stress in the mechanism of acute galactose toxicity in
GALT-deficiency, and raise the intriguing possibility that appropriate dietary supplementation might benefit patients with classic galactosemia.
440B
In Vivo Exposure Impacts of Nano Silver on “Drosophila melanogaster”. Denise K Reaves 1, John J Bang2 , Catherine S Silver Key1. 1) Biology, North
Carolina Central University, Durham, NC; 2) Departments of Environmental, Earth, and Geospatial Science, North Carolina Central, University, Durham,
NC 27707, USA.
Department of Biology, North Carolina Central University, Durham, NC 27707, USA; Departments of Environmental, Earth, and Geospatial Science,
North Carolina Central, University, Durham, NC 27707, USA. Silver is an antimicrobial agent used in many consumer and medical products and causes a
pigmentation defect in humans when ingested in large quantities. Increasingly, silver nanoparticles (AgNP) are permeating the environment as biomedical
and commercial use in on the rise. Our lab has found that adult flies that emerged from silver nanoparticle (AgNP) exposed larvae have reduced locomotion
in a climbing behavior assay and in comparison to control-fed animals, exhibited decreased pigmentation or completely lacked pigmentation. To investigate
the possibility that either the melanin biosynthetic pathway, responsible for dopamine production, or a generalized stress response is involved we have
conducted qPCR assays to assess the transcription levels of genes in these pathways. RNA from newly emerged exposed and non-exposed flies was used in
qPCR to assess expression of the yellow-f, yellow-f2, hsp70, and ple genes. Gene expression patterns observed show variances between the AgNP- exposed
cDNA to wild type with little to no expression in hsp70 and increased levels of expression in ple. Thus, we conclude that consumption of AgNP during
larval development may affect transcription levels of genes involved in the melanin biosynthetic pathway.
441C
Muscle defects associated with human A-type lamin revealed by studies in Drosophila. Om K. Shrestha1 , George Dialyans1, Monika Zwerger2 , Dylan
Thiemann1 , Diane E. Cryderman1, Jan Lammerding2 , Liping Yu1 , Lori L. Wallrath1 . 1) Department of Biochemistry, University of Iowa, Iowa city, IA; 2)
Cell and Molecular Biology and Department of Biomedical Engineering, Cornell University, Ithaca, NY.
Mutations in the human LMNA gene encoding A-type lamins cause a collection of diseases termed laminopathies, including several types of muscular
dystrophy. Lamins are intermediate filaments, which line the inner membrane of nuclear envelope. They are responsible for maintaining the nuclear shape
and regulating gene expression through interactions with chromatin. Heterozygous mutations LMNA, which result in single amino acid substitutions within
the C-terminal Ig-fold domain, were identified in patients with muscular dystrophy. These substitutions were modeled in Drosophila and found to cause
muscle defects. We have taken a multi-disciplinary approach to understanding the molecular basis of these muscle defects. Using biophysical techniques
such as Nuclear Magentic Resonance (NMR) and Circular Dischroism (CD), we determined that the amino acid substitutions caused perturbations of the
tertiary, but not secondary, structure of the Ig-fold. Surprisingly, these structural changes did not result in ‘weakening’ of the nuclear envelope within
myonuclei. However, microarray analysis showed that expression of the mutant lamins in larval muscle caused changes in the expression of genes related to
oxidative stress, neuromuscular junction function, and muscle development. Collectively, these data have revealed the mechanisms by which disease-causing
lamin mutations alter muscle physiology.
442A
dtorsin, the Drosophila ortholog of the early-onset dystonia TOR1A (DYT1), plays a novel role in dopamine metabolism. Noriko Wakabayashi-Ito1,4 ,
Olugbenga Doherty2 , Hideaki Moriyama3 , James Gusella4, Xandra Breakefield1 , Janis O'Donnell2, Naoto Ito 1,4. 1) Dept Neurology, Massachusetts General
Hosp, Charlestown, MA; 2) Dept Biological Science, University of Alabama, Tuscaloosa, AL; 3) School of Biological Science, University of Nebraska-
Lincoln, Lincoln, NE; 4) CHGR, Massachusetts General Hosp, Boston, MA.
Dystonia represents the third most common movement disorder in humans. At least 20 genetic loci (DYT1-20 ) have been identified. TOR1A (DYT1), the
gene responsible for the most common primary hereditary dystonia, encodes torsinA, an AAA ATPase family protein. However, the function of torsinA has
yet to be fully understood. We have created a complete loss-of-function mutant for dtorsin (torp4a ), the only Drosophila ortholog of TOR1A, by
homologous recombination. dtorsin null mutant flies are semi-lethal at pre-pupal stage. The few surviving adults are sterile and slow moving with reduced
cuticle pigmentation. Third instar larvae of the dtorsin-null strain exhibited locomotion defects that were rescued by feeding dopamine. Moreover,
biochemical analysis revealed that the brains of third instar larvae and adults heterozygous for the loss-of-function dtorsin mutation had significantly reduced
dopamine levels. The dtorsin mutant showed a very strong genetic interaction with Pu (Punch: GTP cyclohydrolase), the ortholog of the human gene
underlying dopa-responsive (DYT5) dystonia. Biochemical analyses revealed a severe reduction of GTP cyclohydrolase protein and activity in dtorsin