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University of Chicago
August 1999
Analysis of Segmentation Gene Function and Expression During Arthropod CNS Development
In addition to their role in the specification of the epidermal pattern in each segment, several segment polarity genes, including gooseberry (gsb), specify cell fate in the Drosophila CNS. In the first part of this investigation, the role of gsb in Drosophila CNS development was examined. In the past, analyses of the gsb mutant CNS phenotype were complicated by the fact that the previously available gsb mutants, large deficiencies, have severe segmentation defects and also lack a number of additional genes. In this study, two novel gsb alleles, which have CNS defects, but have weak or no epidermal defects, were characterized. Characterization of these mutants led to a more accurate description of the gsb neural phenotype. Two defects, duplication of the RP2 neurons, and loss of the posterior commissure, were analyzed in more detail. Both defects appear to result from the mis-patterning of neuroblasts (NBs).
In the second part of this investigation, knowledge of Drosophila development was extended in order to compare neural development among distantly related arthropods. Morphological studies suggest that insects and crustaceans of the Class Malacostraca share a set of homologous neurons. However, expression of molecular markers in these neurons has not been investigated, and the homology of insect and malacrustracan NBs, the neural stem cells that produce these neurons, has been questioned. In an attempt to resolve these issues, expression of Even-skipped (Eve) and Engrailed (En), two insect embryonic CNS markers, was examined across a number of arthropod species. This molecular analysis allowed for verification of the homology of previously identified malacostracan neurons and identification of additional potentially homologous neurons. Engrailed NB expression was also found to be conserved, indicating that insect and crustacean NBs are homologous.
In an attempt to examine expression of a second insect NB marker in crustaceans, a wingless (wg) orthologue was cloned fromthe malacostracan crustacean Mysidium columbiae (mysid). Although analysis of the expression of this gene did not lead to a better understanding of mysid neurogenesis, it provides the first molecular evidence suggesting that the processes of mesodermal and retinal patterning are conserved among distantly related arthropods.
Education:
Fall 1994 to 1999
University of Chicago, Molecular Genetics and Cell Biology Doctoral Program Expect to complete my dissertation in summer 1999.
1994
University of Notre Dame Biology Major, Bachelor of Science,
Research Experience:
University of Chicago, Dr. Nipam Patel's Lab (present)
"Analysis of the role of segmentation genes in the neural development of Drosophila and other arthropods, with focus on cell fate specification, cell signaling, axon guidance, and comparative development".
University of Notre Dame Biology Department, Dr. Elizabeth Eldon's Lab (1992-1994)
Examined the role of the 18-wheeler gene in Drosophila development.
Conference Presentations:
Duman-Scheel, M. and N.H. Patel, Analysis of molecular marker expression reveals neuronal homology among arthropods, Oral presentation, Midwest Developmental Biology Meeting, Indianapolis, IN, 1998
Duman-Scheel, M. and N. H. Patel, Analysis of the role of segmentation genes in arthropod CNS Development, Guest speaker at the University of Notre Dame Drosophila Group Meeting, Notre Dame, IN, 1998
Duman-Scheel, M. and N. H. Patel, Analysis of the role of segmentation genes in arthropod neural development, Poster presentation, Society of Developmental Biology International Congress, Snowbird, Utah, 1997.
Duman-Scheel, M. and N.H. Patel, Analysis of the role of segmentation genes in neural development, Oral presentation, Midwest Developmental Biology Meeting, Indianapolis, IN, 1997.
Duman-Scheel, M. and N.H. Patel, Analysis of the role of gooseberry in posterior commissure formation. Poster presentation, 38th Annual Drosophila Research Conference, Chicago, Illinois, 1997.
Duman-Scheel, M., and N.H. Patel, Analysis of the role of segment polarity genes in neural patterning. Poster presentation, 37th Annual Drosophila Research Conference, San Diego, 1996.
Duman-Scheel, M. and N.H. Patel, Analysis of the role of segmentation genes in Drosophila neural development. Poster presentation, Midwest Developmental Biology Meeting, Chicago, IL, 1996.
Publications:
Duman-Scheel, M. and N.H. Patel (1999). Analysis of molecular marker expression reveals neuronal homology in distantly related arthropods. Development 126:2327-2334.
Duman-Scheel, M., X. Li, I. Orlov, M. Noll, and N. H. Patel (1997). Genetic separation of neural and cuticular patterning functions of gooseberry. Development 124: 2855- 2865.
Eldon, E., S. Kooyer, D. D'Evelyn, M. Duman, P. Lawinger, J. Botas, H. Bellen (1994). The Drosophila 18 wheeler gene is required for morphogenesis and has striking similarities to Toll. Development 120: 885-899.
Research Summary:
- The goal of my thesis project is to gain a better understanding of neural patterning in a variety of arthropods. My project began with an analysis of CNS patterning in Drosophila. Several Drosophila segmentation genes, including the transcription factor gooseberry (gsb), specify cell fate in the Drosophila CNS. I have characterized two gsb mutants which exhibit CNS defects, including RP2 neuron duplication and loss or reduction of the posterior commissure. These mutants allowed me to examine the genetic interactions between gsb and other segment polarity genes in the specification of RP2 neural fate. Currently, I am investigating the cause of the gsb posterior commissure defect. In gsb mutants, the posterior commissure is lost or reduced in each segment, a phenotype which could result from alterations in the neurons which pioneer the posterior commissure or changes in the midline cells that guide the axonal projections of commissural axons.
- I also hope to extend our knowledge of Drosophila CNS development in order to better understand neural patterning in other arthropods. Insects and crustaceans appear to share a number of homologous neurons, but the expression of molecular markers in these neurons as well as the neural precursor cells that produce them has not been investigated. I am examining the expression of a number of neural and neuroblast molecular markers in a variety of crustaceans. This investigation has allowed me to verify the homology of previously identified crustacean neurons and to discover additional neurons that closely resemble those found in insects. This work also indicates that insect and crustacean neuroblasts are homologous. These discoveries will allow us pursue more detailed investigations of CNS development in a variety of arthropods.
