Thesis Defense Announcement
To: the George Mason Community
Sarah Trunnell
Master of Science in Biology
Molecular Biology concentration
Date: Monday July 26, 2010
Time: 1:00 - 3:00 P.M.
Place: Occoquan Bldg., Room 312-G
Prince William campus
Thesis Chair: Dr. Daniel N. Cox, MMB Dept.
Title:
"THE
DROSOPHILA SPECTRAPLAKIN SHORT STOP
DIFFERENTIALLY REGULATES CLASS SPECIFIC DENDRITE MORPHOGENESIS"
Abstract:
Disorders
of the nervous system can often be attributed to developmental
abnormalities
occurring during neurogenesis, which affect the morphology, and
ultimately
functionality of neurons. In order to understand how the nervous system
successfully matures, it is essential to uncover the molecular
mechanisms
governing neural development. The
peripheral nervous system (PNS) of Drosophila
melanogaster, provides an excellent model system in which to
elucidate the
molecular mechanisms governing dendrite morphogenesis. Spectraplakins
are an evolutionarily
conserved family of cytoskeletal cross-linking proteins that provide a
link
between the actin and microtubule cytoskeletons. Given
that cytoskeletal structure and
organization are key mediators of neuronal shape, and by extension
neuronal
function, understanding the molecular mechanisms underlying the
regulation of
cytoskeletal dynamics in neurons is important to achieving insight into
the
process of class-specific neuronal dendrite morphogenesis.
To address the role of Spectraplakins in
dendrite morphogenesis, this thesis focuses on investigating the sole
known
Spectraplakin gene in Drosophila
referred to as short stop (shot).
This research demonstrates that shot
exerts differential effects on class specific dendrite morphogenesis of
Drosophila dendritic arborization (da)
neurons of the PNS. Comparative
morphological analyses reveal shot is
required to restrict dendritic complexity among the simpler class I and
II da
neurons, whereas shot is required to promote
dendritic complexity among the more complex class III and IV da neurons. Taken together, these results suggest
dendrite morphogenesis is subject to context-dependent regulation
mediated via shot.
Immunohistochemistry analyses further reveal that Shot protein
is
expressed in all da neurons. Collectively,
these studies provide novel insight into the role of Spectraplakins in
dendrite
development and suggest the importance of cross talk between the actin
and
microtubule cytoskeletons in mediating neuron-specific patterns of
dendrite
arborization.
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