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Poster Full Abstracts - Neural Development
Poster board number is above title. The first author is the presenter
310
RBG cells are involved in guiding the axon of photoreceptor cells toward the optic stalk and wrapping the axon. Previous studies have reported that the
number of ommatidia and RBGs in eye disc have a relatively fixed ratio.However, the actual ratio differs in different reports. We still do not know whether
number of ommatidia and RBG cells match during development of
Drosophila
eye. Here, we closely monitored the number of ommatidia and RBGs in
different developmental stages ranging from 2nd instar larvae to 4hrs after puparium formation (APF) of wild type flies. We observed that the
ommatidia/RBGs ratio is one at early stage. Along with the development, the number of ommatidia increases; however, number of RBG cells remains
plateau after mid late 3rd instar or after 15 rows of ommatidia development. The ommatidia/RBG ratio becomes around two at 4hrs APF. In genetically
manipulated flies with increased number of ommatidia, more RBGs cells were found in the eye disc and the ommatidia/RBG ratio remained around two
similar to wild type flies.Further,In small eye mutants, where the number of RBGs reduced, the ommatidia/RBGs ratio also remained around two. These
findings suggest a mechanism to match the number between ommatidia and RBG cells; possibly, photoreceptor regulates number of RBG cells for final
adjustment of ommatidia/RBGs ratio. Possible mechanisms involve in such number matching may be migration, proliferation or survival/apoptosis of the
RBG in response to the changes in ommatidia number.
669C
Glial remodeling during reorganization of the peripheral nervous system.
Matthew Siefert, Soumya Banerjee, Bridget Hartman, Tara Fallah, Todd
Simmons, John Wilber, Dorothy Lakis. Zoology, Miami University, Oxford, OH.
During metamorphosis of
Drosophila
, the nervous system is remodeled to execute developed adult specific behaviors. One of the morphological changes
is the fusion of posterior abdominal nerves (A4-A8) to form a terminal nerve trunk (TNT). The objective of our study is to understand how glial
ensheathment of individual nerves in the larva is rearranged to form the TNT. Four layers are known to ensheath individual nerves (Stork et al 2008) the
outer layer, the neural lamella (NL) which is an extra cellular matrix, the perineurial glia (PG) present just below the lamella, the subperineurial glia (SPG),
and lastly the wrapping glia (WG). Using layer specific markers, we have seen that the NL is absent just before TNT formation and remains absent until the
72h after puparium formation (APF) stage. This has been confirmed using electron microscopy at 28h APF, a time when the transition to the TNT begins.
Using anti-repo, we observe a 3 fold increase in the total number of glial cells at 24h APF, and roughly 80% of these cells are PG. Because this layer is
prevalent throughout metamorphosis, our current research is focused on the contribution of PG to the formation of the TNT. We plan to target the cell death
gene
reaper
to PG at time points that coincide with proliferation and differentiation of glial cells. We anticipate that this manipulation will lead to
abnormalities in the TNT formtaion. Another aspect of the project is to manipulate glial process outgrowth to test its role in TNT formation.
670A
Dissecting the regulation of a novel gene cg11910 in the longitudinal glial cells of drosophila embryos.
Pavithra Vivekanand
1
, Jaclyn Malat
2
. 1)
Biology, Dickinson College, Carlise, PA; 2) Franklin and Marshall College, Biology Department, Lancaster, PA 17604.
The long-term goal of this research project is to understand the molecular mechanisms that regulate the differentiation of glial cells within the central
nervous system (CNS) of Drosophila. Within the NS of Drosophila, the glial cells are broadly divided into two classes, the midline and lateral glia, based on
their cellular origin and location within the VNC. The midline glial (MG) cells develop from mesectodermal tissue, while the lateral glial cells arise from the
neuroectoderm. The differentiation of the lateral glial cells is regulated by the transient expression of the transcription factor, Glial cells missing (Gcm). Gcm
initiates lateral glial cell differentiation by inducing the expression of downstream transcription factors such as Reversed polarity (Repo), Pointed (Pnt) and
Tramtrack (Ttk). While the initial events of lateral glial cell determination have been well characterized, the generation of diversity in the sub-types of lateral
glial cells is poorly understood. In order to understand how cell fate specification of the different types of lateral glial cells is established, we are
investigating the regulation of a novel gene cg11910 that is expressed in longtidudinal glial cells. The regulatory region of cg11910 has predicted binding
sites for Repo and Pnt, which suggests that Repo and Pnt might regulate its expression. Consistent with this hypothesis cg11910 mRNA expression is
drastically reduced in gcm mutants and completely abolished in both repo and pnt mutant embryos. To determine whether cg11910 expression is directly
regulated by Repo and Pnt we will perform transcription assays in Drosophila cultured cells and generate transgenic flies expressing GFP reporter constructs
under the control of the identified upstream regulatory region.
671B
The actions of gonadotropic hormones on the development and mature function of a defined neural circuit in
Drosophila melanogaster
.
Selma
Avdagic, Bhatt Parag, Neckameyer Wendi. Pharmacological and Physiological Science, Saint Louis University School of Medicine, St. Louis, MO.
In the fruit fly,
Drosophila melanogaster
, serotonin (5-HT) functions both as a neurotransmitter to regulate larval feeding, and in the development of the
stomatogastric feeding circuit. We have shown an inverse relationship between developmental 5-HT levels and the complexity of the 5-HT axonal fibers
projecting from the brain to the foregut, which correlates with perturbations in feeding, the functional output of the circuit (Neckameyer, 2010). These
effects are distinct from the actions of 5-HT as a neurotransmitter. We have also shown that although dopamine (DA) neurotransmission does not modulate
feeding, perturbed levels of neuronal DA during development affect both 5-HT innervation of the gut as well as larval feeding behavior. Using transgenic
and pharmacological approaches, we have manipulated levels of the critical gonadotropic hormones (juvenile hormone and ecdysteroids) in the brain and the
fat body (a sexually dimorphic tissue that secrete hormones) during CNS development. Our preliminary studies have established that, as for mammals,
gonadotropic hormones affect the development of neural circuitry, which is sensitive to the sexual identity of the tissue. Funded by National Science
Foundation Grant No. 061606.
672C
Sexual identity affects the development and mature function of a defined neural circuit in
Drosophila
melanogaster.
Parag Bhatt, Selma Avdagic,
Wendi Neckameyer. Pharmcological and Physiological Science, Saint Louis University School of Medicine, St Louis, MO.
In the fruit fly,
Drosophila melanogaster
, serotonin (5-HT) functions both as a neurotransmitter to regulate larval feeding, and in the development of the
stomatogastric feeding circuit. We have shown an inverse relationship between developmental 5-HT levels and the complexity of the 5-HT axonal fibers
projecting from the brain to the foregut, which correlates with perturbations in feeding, the functional output of the circuit (Neckameyer, 2010). These
effects are distinct from the actions of 5-HT as a neurotransmitter. We have also shown that although dopamine (DA) neurotransmission does not modulate