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Poster Full Abstracts - Evolution and Quantitative Genetics
Poster board number is above title. The first author is the presenter
273
529A
Pleiotropy effects of
Syndecan
on innate immune responses and life span of
Drosophila melanogaster
.
Chia-Hua Lue
1
, Maria De Luca
2
, Jeff Leips
1
. 1)
Biological Sciences, University of Maryland Baltimore County, Baltimore, MD; 2) Department of Nutrition Sciences, University of Alabama at
Birmingham.
Life history theory is based on the premise that the competing energetic demands of growth, development, somatic maintenance, reproduction and storage
give rise to trade-offs among traits. Genes controlling such trade-offs are expected to play an important role in life history evolution. In a previous mapping
study we identified the gene
Syndecan
as candidate gene influencing natural variation in lipid storage in
Dorosphila melangoster
. Follow up studies showed
that tissue specific alterations of the expression of
Syndecan
(in the fat body and brain) caused changes in a number of traits including metabolism, and sleep
wake patterns. Given the influence of
Syndecan
on metabolism and lipid storage and known correlations between these traits with life span and immunity,
here we explored the pleiotropic effects of
Syndecan
expression on these traits. We used the GAL4/UAS system in
Drosophila
to knockdown expression of
Syndecan
in the fat body and brain tissue then measured life span and age - specific immune responses in male and female virgin flies. For the immune
response assay we measured the ability of flies to clear an
E. coli
infection at one, three, and five weeks of age. Our results indicated that the population with
knockdown
Syndecan
gene in fat body tissue had poorer innate immune response and shorter life span than control population. The innate immune response
displayed especially significant difference at early ages in both sexes. However, knockdown of
Syndecan
expression in central nervous system tissue caused
a significant improvement of bacterial clearance capability and extended life span relative to that of control flies. Thus, variation in the expression of
Syndecan
has extensive pleiotropic effects with different consequences for life span and immune response depending on the tissue it is expressed in. We are
currently doing studies to understand underlying mechanism of these pleiotropic effects.
530B
Naturally Occurring Mutational Variation in Sleep Traits in
Drosphila melanogaster
.
Rachel A Lyman
1
, Trudy F C Mackay
2,3
, Mary Anna Carbone
2,3
,
Susan T Harbison
2,3
, Matthew Jones-Rhoades
1
, Richard F Lyman
2,3
. 1) Dept of Biology, Knox College, Galesburg, IL; 2) Dept of Genetics, NCSU, Raleigh,
NC; 3) W M Keck Center for Behavioral Biology, NCSU, Raleigh, NC.
To provide a better understanding of spontaneous mutation rates and the types and locations of spontaneous mutations, we constructed a new set of 25
mutation accumulation (MA) lines from an inbred line of the
Drosophila
Genetic Reference Panel. The MA lines were maintained in small mass matings of
10 males and females per generation at a standard population density with discrete generations. We measured MA lines from generation 60, and subsequent
generations, for behavioral (sleep, startle response, productivity), morphological (bristle number), physiological (body mass, gene expression) and a
multigeneration competitive fitness assay. We found significant mutational variation for sleep traits. We performed analyses of genome wide variation in
gene expression using Affymetrix GeneChip Drosophila Genome 2.0 Arrays to identify differentially expressed genes. We then determined for which loci
variation in gene expression was associated with sleep traits to identify candidate
de novo
mutations associated sleep phenotypes.
531C
A Surprisingly Complex Genetic Architecture for Starvation Resistance Revealed by Multiple QTL Mapping Designs.
Casey McNeil, Clint Bain,
Stuart Macdonald. Molecular Biosciences, University of Kansas, Lawrence, KS.
In nature, animals must often survive periods of nutrient deprivation, and the ability to withstand starvation an important life-history trait. There is
substantial genetic variation for starvation resistance in
Drosophila
, and several candidate genes related to nutrient acquisition, storage, and metabolism have
been identified. To validate these genes, identify novel loci, and generate robust estimates of the effects and frequencies of causative alleles, we genetically
dissected starvation resistance using the
Drosophila
Synthetic Population Resource (DSPR). The DSPR consists of recombinant inbred lines (RILs) derived
from two highly recombinant eight-way synthetic populations, allowing for high-resolution mapping of QTL (quantitative trait loci). Assaying >1700
homozygous RILs we map 20, typically sex-specific QTL to small intervals (<0.5Mb), containing a median number of 68 genes. Individual QTL explain
3.5-13.3% of the phenotypic variation, and half are rare -- the minor allele is unique to a single founder line. To further characterize these starvation
resistance QTL and potentially identify novel, context-dependent loci, we dissected the trait using ~2500 heterozygous genotypes over three additional
mapping designs. First, pairs of RILs were intercrossed and heterozygous female progeny (RIX design) were assayed. Second, we separately crossed RILs to
two isogenic reference strains, and assayed
trans
-heterozygous female progeny (backcross design). In the RIX design we confirm 3/5 QTL originally
mapped in homozygous females, implying the two unconfirmed QTL may be products of inbreeding depression. In addition, we identify multiple novel,
cross-specific QTL. Surprisingly, each backcross mapping design results in a genetic architecture distinct from that observed in any other design, suggesting
a strong role for genetic background effects. Our work reveals an unexpectedly complex genetic architecture underlying an important life-history trait, and
the fine-scale nature of mapped QTL advances our efforts to identify the causative sites.
532A
The impact of artificial selection for the wing shape on fluctuating asymmetry in four Drosophila species.
Bianca F. Menezes, Blanche Bitner-Mathé.
UFRJ, Rio de Janeiro, Brazil.
Fluctuating asymmetry (FA), the unassigned difference between the two sides of a bilaterally symmetrical trait, has been proposed as a useful tool for
estimating changes in developmental instability and quantification of the degree of environmental and genetic stress that individuals experience during their
development. Recent approaches have used left-right (L-R) variations in the size and shape of the Drosophila wings to describe levels of FA in natural
populations under stress conditions. Whether artificial selection for the wing shape can increases FA remains an open question. In our laboratory, replicate
lines were obtained by artificial selection for rounded or elongated wing shapes from natural populations of D. melanogaster, D. willistoni, D. hydei and D.
mediopunctata. We used these lines to compare intra- and interspecific patterns of FA in wing morphology and whether there is difference between the long
and rounded lines. All the wing traits were affected in different magnitudes within and among species. We detected significant intra- and interspecific
differences in levels of FA in wing size and wing length. Only D. willistoni demonstrated fluctuating asymmetry on wing shape due to a possible
antisymmetry, which might be correlated. Interspecific results presented significant levels of FA in all wing size traits among the rounded lines, including
wing width and wing shape. Our results suggest that, under the same selection pressure, natural adaptation to artificial selection for the wing shape varies
among species due to selection direction.