Genetic requirements for initiation of Aspergillus nidulans conidiophore development /
Conidiation in the filamentous fungus Aspergillus nidulans
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1997.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739888051&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Conidiation in the filamentous fungus Aspergillus nidulans requires the activation of brla, a well characterized transcriptional regulator of genes that are induced specifically during asexual development. This dissertation describes two related mutant screens that were performed in order to isolate mutants that were blocked in developmental stages that occur prior to brla activation. In the first screen, a haploid strain of A. nidulans was mutagenized and six different genes were identified fluG,flbA,flbB,flbC,flbD, and flbe that when mutated give rise to colonies with varying fluffy phenotypes that express drastically reduced levels of brla . In the second screen, a diploid strain was mutagenized and dominant fluffy mutants were isolated that likely result from either dominant activating in genes not identified in the recessive screen or from dominant interfering mutations in genes that may have been isolated in the haploid screen. Mutations in the flbB,flbC,flbD, and flbe genes result in a fluffy phenotype described as delayed conidiation because these mutant colonies are delayed at least 24 h in their ability to initiate conidiophore development. I focused on the isolation and characterization of the flbB,flbC,flbD, and flbe genes and have shown that flbB,flbC, and flbd each encode proteins with similarities to known DNA binding proteins. flbB is predicted to encode a protein with similarity to b-zip DNA binding proteins while flbc putatively encodes a protein that has a zinc finger domain, and flbd a myb-like DNA binding domain. Overexpression of flbd in liquid culture results in the brlA expression and the production of conidiophores indicating that flbd functions directly in activating brIA and development. TheflbB,flbC,flbD, and.flbe genes are expressed throughout the asexual life cycle of A. nidulans indicating that the products of these genes are controlled post- transcriptionally. A model describing the complex interactions of all the genes isolated and characterized from the two screens is presented. |
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| Item Description: | Vita. "Major Subject: Biology". |
| Physical Description: | x, 143 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 126-136. |