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Poster Full Abstracts - Evolution and Quantitative Genetics
Poster board number is above title. The first author is the presenter
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meaning cross-species comparisons at any temperature could be misleading. Numerous temperature-dependent embryonic events must be precisely tuned for
proper development and viability, as the embryo is the most temperature-sensitive, but also most easily monitored, stage. With time-lapse imaging, we
monitored 26 events spanning embryonic development in multiple species across their viable temperature ranges. We found embryonic development has a
non-linear temperature dependence that changes between species, including the broader viable temperature ranges of cosmopolitan species compared to
island species. We characterized the correlation between the native environment and the viable growth ranges, which informs how underlying adaptations
may affect adaptation to new environments.
461B
Evolution of Mesoderm Invagination in the Insect Order Diptera.
Steffen Lemke
1
, Silvia Urbansky
1
, Thomas Sandmann
2
. 1) Centre for Organismal
Studies (COS), Universität Heidelberg, Heidelberg, Germany; 2) Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany.
In
Drosophila
, the onset of mesoderm internalization is marked by pulsed apical constrictions in a band of cells on the ventral side of the embryo.
Following apical constriction, the nuclei of these initially columnar ventral cells drop basally, the cells assume a wedge-shaped morphology, and the ventral
epithelium bends to form a shallow furrow along the ventral midline. This furrow then rapidly contracts into a deep invagination as cells within the furrow
shorten by about 50% along their apical-basal axes. This internalization of mesodermal cells is mainly driven by the contraction of an apical and junctional
actin network that coalesces after apical localization of non-muscle myosin II. Apical localization and activation of myosin II is promoted by apical
RhoGEF2, which is independently controlled by
T48
and
folded gastrulation
(fog).
Mesoderm invagination without formation of a prominent ventral furrow has been reported for dipterans in the nematoceran suborder, including gnats and
mosquitoes. To functionally test for putative genetic changes underlying different modes of mesoderm invagination within the insect order Diptera, we study
these gastrulation movements in the nematoceran midge
Chironomus riparius
. We will present results from our ongoing study and the sequenced blastoderm
transcriptome of
Chironomus riparius
as gene identification tool.
462C
Exploring the molecular basis of insect wing evolution: a comparison of beetle and fly wing development.
David M. Linz, Yoshinori Tomoyasu.
Zoology Department, Miami University, Oxford, OH.
We are studying the gene regulatory network of wing development in
Tribolium
(the red flour beetle) and comparing it to that of the fruit fly,
Drosophila
,
to understand the molecular basis of morphological evolution. The wings of these two insects have become vastly different over evolutionary time. The fly
has typical flight wings on the second thoracic segment (T2), but has intensively modified wings (halteres) on T3. In contrast, the beetle has a pair of
hardened protective structures (elytra) on T2, and uses the T3 hindwings for flight. We have been analyzing the function of potential “wing genes” selected
from previous
Drosophila
studies in
Tribolium
wing development (candidate gene approach). However, as these studies have progressed, the choices of
candidate genes have become increasingly limited and also created a fly-biased view of insect wing evolution. To gain a more complete view of insect wing
evolution, we have started exploring genes that could be unique to insects other than
Drosophila
. We first examined a class of developmental genes (toolkit
genes) that are known to be important for embryonic segmentation in
Drosophila
. These toolkit genes tend to show a high degree of pleiotropy, therefore
increasing the likelihood of finding novel wing genes in the beetle. Despite this, we found no definitive examples of wing specific genes. To obtain further
insight into the molecular basis of insect wing evolution, we are adopting a
bona fide
non-candidate gene approach: RNA sequencing. By comparing the
transcriptome from dorsal appendages in both the fly and beetle, changes in developmental mechanisms that have contributed to their morphological
evolution can be fully explored and characterized.
463A
Evolution of Shape by Multiple Regulatory Changes to a Growth Gene.
David Loehlin, John Werren. Biology, University of Rochester, Rochester, NY.
What genes and genetic changes are responsible for morphological differences between species? Here we identify a major gene that induces male-specific
wing size and shape differences between
Nasonia
wasp species. Fine-scale mapping and in situ hybridization reveals that changes in at least three regions
(two strictly non-coding) around the gene unpaired-like (upd-like) cause changes in spatial and temporal expression of upd-like in the developing wing and
corresponding changes in wing width. Upd-like is a
Nasonia
homolog of
unpaired
, a well-studied signaling protein that regulates cell proliferation and
differentiation. Our results indicate that multiple changes in the regulation of upd-like are involved in microevolution of morphological and sex-specific
differences between species.
464B
Region specific patterning function of Pax6 in the developing embryonic head of Tribolium Castaneum.
Qing Luan
1
, Arun Sasikala-Appukuttan
1
,
Markus Friedrich
1,2
. 1) Biological science, Wayne State University, Detroit, MI; 2) Department of Anatomy and Cell Biology, Wayne State University,
School of Medicine,Detroit, MI.
Because of this high degree of evolutionary conservation, major research investments have been made in studying the role of Pax6 in a variety of species.
One consistent picture emerging from these studies is that Pax6 functions as high-level regulator. However, exactly how Pax6 executes its patterning role
during visual system development and, by extension, how Pax6 acquired its role in eye development during evolution is still fundamentally debated.
Previous work in our lab produced preliminary evidence that the Pax6 transcription factor paralogs eyeless (ey) and twin of eyeless (toy) are not only
required for the normal development of the larval eyes but a larger region of the developing embryonic head. We have extended this analysis generating a
high resolution map of ey+toy sensitive regions in the Tribolium larval head cuticle. These data demonstrate that Tribolium Pax6 is responsible for the
normal development of a large region in the embryonic procephalon. We are now studying the mechanistic basis of these effects by examining pattern
formation and marker gene expression in Tribolium ey+toy knockdown embryos.
465C
X-linkage and the evolution of sex-biased gene expression.
Richard P. Meisel
1
, John H. Malone
2
, Andrew G. Clark
1
. 1) Dept Molec Biol & Gen, Cornell
Univ, Ithaca, NY; 2) Dept Biol Sci, Florida State Univ, Tallahassee, FL.