Transcriptional regulation of the period gene and its relationship to circadian locomotor activity rhythms in Drosophila melanogaster /
Circadian fluctuations in the Drosophila period (per) gene
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1997.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=736823791&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Circadian fluctuations in the Drosophila period (per) gene mRNA and protein levels comprise an auto-regulatory feedback loop which is necessary for circadian clock function in flies. While considerable progress has been made in the understanding of PER protein oscillation, the regulation of per mRNA cycling is not as well characterized yet. In this dissertation, a 69bp circadian regulatory sequence (CRS) has been identified in per upstream sequences and shown capable of conferring normal per expression patterns in an enhancer like fashion. CRS is sufficient to drive per mRNA cycling and mediate strong behavioral rescue. per gene first intron (intron 1) sequence drives low level expression in lateral neuron and glial cells in the brain and low amplitude mRNA cycling. Three copies of CRS (3CRS) produce high levels of constitutive mRNA and high levels of PER which completely repress endogenous per[] transcription. However, PER generated from intron 1 and 3CRS cycles and mediates low penetrance behavioral rescue. These results suggest that per gene expression is fine tuned both in absolute expression levels and in the circadian cycling of abundance in order to manifest robust behavioral rescue, whereas without mRNA cycling, PER can mediate behavioral rescue but only with a low penetrance. For further delimiting the circadian enhancer in CRS, linker scanning mutations throughout CRS have been generated and tested for their ability to confer behavioral rescue. Two out of 7 mutations tested mediate strong behavioral rescue, two others weak behavioral rescue, while the remaining three mutations covering the E-box and 10bp adjacent 3' flanking sequences exhibit no behavioral rescue. In gel mobility retardation experiments several fly head nuclear proteins bind CRS and the binding is affected by mutations in CRS. No clear correlation has been observed between gel mobility retardation and behavioral rescue experiments. One factor binds to the 3' half of CRS but not the 5' half although the two fragments overlap by 18bp including the E-box and 6bp flanking sequence on each side. The binding of this factor may be correlated with the loss of behavioral rescue capability in the three mutations. |
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| Item Description: | Vita. "Major Subject: Biology". |
| Physical Description: | xii, 99 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 88-97. |