Characterization and expression of evolutionarily conserved regulatory genes in Ilyanassa obsoleta.
Item
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Title
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Characterization and expression of evolutionarily conserved regulatory genes in Ilyanassa obsoleta.
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Identifier
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AAI9830743
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identifier
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9830743
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Creator
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Moshel, Sharon Maureen.
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Contributor
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Adviser: J. R. Collier
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Date
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1998
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Genetics | Biology, Zoology
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Abstract
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My strategy for studying the role of cytoplasmic determinants on gene expression in Ilyanassa obsoleta was to isolate evolutionarily conserved regulatory genes whose putative role in Ilyanassa development would be in polar lobe dependent structures.;Early experiments with an engrailed antibody showed engrailed localization in the shell gland, a polar lobe dependent structure. Because of these results, I attempted to isolate an engrailed homolog from the Ilyanassa genome. Using degenerative primers against the conserved homeobox region of engrailed, I identified an engrailed homolog in Ilyanassa which shares an 80% amino acid homology to the Drosophila gene. Using in situ hybridization and immunocytochemistry I have demonstrated engrailed localization solely to the shell gland. While the removal of the polar lobe disrupts the formation of an external shell, internal shell fragments are still present. These fragments stain positive for engrailed, illustrating engrailed expression is not polar lobe dependent. I propose the function of engrailed in Ilyanassa is to define shell gland cells, after their initial determination, which will lead to the terminal differentiation of the shell.;The second gene I isolated was twist, a helix-loop-helix gene, known to have a significant role in mesoderm differentiation in Drosophila and other organisms. Using the PCR, I identified an Ilyanassa twist homolog sharing an 82% identity with the bHLH region of Drosophila twist. In situ hybridization and immunocytochemistry have determined the role of twist as a mesoderm-specific transcription factor has also been conserved in Ilyanassa. In normal embryos, twist is expressed in the nuclei of the precursor cells of entomesoderm, a polar lobe dependent lineage. The removal of the polar lobe abolishes all staining of twist demonstrating that not only is the role of twist as a mesoderm-specific transcription factor conserved in Ilyanassa, the cytoplasmic factor(s) found in the polar lobe are essential for the translation of twist.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
