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 Title: Developmental expression of a 4.5S RNA and variants of U1snRNA in Drosophila melanogaster Author(s): Koehler, Richard Fred Doctoral Committee Chair(s): Steffensen, D.M. Department / Program: Biology Discipline: Biology Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Biology, Molecular Biology, Genetics Abstract: Analysis of small RNAs in Drosophila melanogaster revealed the existence of a 4.5S RNA and variants for the U1 snRNA. The 4.5S RNA was separated from other snRNAs by electrophoresis through high percentage polyacrylamide gels. The Drosophila 4.5S RNA migrated at the same rate as the mouse 4.5S$\sb{\rm I}$ RNA standard. Chemical sequence analysis of the 3$\sp\prime$ end of the Drosophila 4.5S RNA revealed a 60% nucleotide homology with the mouse 4.5S$\sb{\rm I}$ RNA. The mouse 4.5S$\sb{\rm I}$ RNA is related to the B$\sb2$ repeat of the mouse genome. The existence and homology of the Drosophila 4.5S RNA to the mouse 4.5S$\sb{\rm I}$ RNA may provide a focal point for the study of the origins of repeated sequences.The U1 snRNA variants of Drosophila were separated by electrophoresis through high percentage polyacrylamide gels. A comparison of the U1 variants from unfertilized eggs, second and third instar larva, and adult flies revealed developmental differences in their expression. In unfertilized eggs the U1 snRNA is absent or in very low concentration. In second and third instar larva there are at least two variants for the U1 snRNA, while in adult flies there are at least 4 variants. The nature of the variants was not determined; however, each variant hybridized to a U1 snRNA specific probe. Developmental differences were also observed for variants of the U4 and U6 snRNAs. The U2 snRNA of Drosophila showed a large difference in migration rate between third instar larva and adult flies. The adult U2 migrated significantly faster than the third instar U2. Since only one nucleotide sequence is known for the U2 snRNA, the differences in migration may be due to developmentally-regulated base modifications. These snRNA variants may be involved in the alternative splicing of primary transcripts. The snRNA variants may produce functionally-different spliceosomes that splice primary transcripts in a developmental- or tissue-specific manner. Issue Date: 1991 Type: Text Language: English URI: http://hdl.handle.net/2142/22857 Rights Information: Copyright 1991 Koehler, Richard Fred Date Available in IDEALS: 2011-05-07 Identifier in Online Catalog: AAI9136639 OCLC Identifier: (UMI)AAI9136639
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