Isolation and characterization of developmental genes in Aspergillus nidulans /
Asexual reproduction in the filamentous fungus Aspergillus nidulans requires the correct temporal and spatial expression of many different genes. Of central importance in this process is the activation and function of the developmental regulatory gene brlA. Inappropriate expression of brlA results...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739668331&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Asexual reproduction in the filamentous fungus Aspergillus nidulans requires the correct temporal and spatial expression of many different genes. Of central importance in this process is the activation and function of the developmental regulatory gene brlA. Inappropriate expression of brlA results in activation of the developmental pathway, spore production and global inhibition of growth. This dissertation describes two novel approaches that utilize the brlA-induced growth inhibition phenotype to identify genes involved in asexual development. Developmental genes that are essential or have redundant functions would not be identified in traditional visual screens based on their loss of function. The first screen was based on a gain of function phenotype (conditional growth inhibition) and used an inducible library to identify genes, that when overexpressed, lead to growth inhibition through activation of brlA. Sixteen mutants were identified that could conditionally express brlA and cause growth inhibition. These mutants were designated FAB mutants (Forced expression Activation of brlA). Five fab genes were isolated and FabA was found to be brlA, supporting the effectiveness of this screen. Overexpression of fabM causes wavy hyphae, brlA MRNA accumulation and spore production. fabM is predicted to encode an essential product that shares significant homology to poly(A)-binding proteins. Overexpression of fabP and fabO causes extensive hyphal curling, brlA MRNA accumulation and in fabP, spore production. fabP is predicted to encode a serine-threonine kinase, the first kinase found to be involved in A. nidulans asexual development. In the second screen, a strain in which brlA could be conditionally induced was mutagenized and survivors selected for their ability to grow when brlA was expressed. This screen identified the previously characterized developmental genes abaA, flbB, and flbD and four new loci designated sbr for suppresser of brlA response. sbrA and SbrB mutants produce conidiophore stalks that branch near the apex and produce few spores. brlA expression in a sbrA mutant is lower than wild-type and sbrA was found to be required for expression of abaA. |
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| Item Description: | Vita. "Major Subject: Biology". |
| Physical Description: | xi, 138 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 119-128. |