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Abstract Detail

Mycological Section

Hill, Terry W. [1], Jackson-Hayes, Loretta [2], Haugen, Benard J. [1], Hohlt, Anne E. [1].

A temperature-sensitive mutation in the ActA gene affects cell morphology in Aspergillus nidulans.

We have identified a novel mutation in an NQO-mutagenized strain of the filamentous fungus Aspergillus nidulans, which impairs hyphal morphology at a restrictive temperature of 42°C. Compared to wild type, hyphal width is irregular and significantly increased in mutant strains, compartment length is shortened, the cytoplasm is highly vacuolated, and apical walls are easily ruptured. The mutation was meiotically mapped to the right arm of Chromosome I, exhibiting a ca. 26% recombination frequency in crosses involving the yA2 allele, ca. 11% in crosses involving proA1, ca. 5.5% in crosses with lysF51, and ca. 0.6% in crosses with pabaA1. After sequencing several candidate genes in the indicated region, we identified a mutation in the actA gene (AN6542), which encodes the cytoskeletal protein actin. The mutant allele, which we designate actA1, contains a G-to-T base transversion at position 1603 (out of 1786 nucleotides), which is predicted to cause a lysine-to-asparagine substitution at conserved position 315 of the 375-residue gene product. All aspects of the phenotype are complemented by introduction of the wild type actA allele. In actA1 strains expressing a GFP-tagged version of the type-V myosin MyoE, the GFP signal is located in the Spitzenkörper at permissive temperature; at restrictive temperature, however, the signal relocates to the apical plasma membrane. These observations suggest that a defect in vesicle trafficking in the hyphal apex may underlie the major morphological aspects of the phenotype.

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1 - Rhodes College, Biology, 2000 North Parkway, Memphis, TN, 38112, USA
2 - Rhodes College, Chemistry, 2000 North Parkway, Memphis, TN, 38112, USA

Actin mutation
hyphal morphogenesis.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PMY062
Abstract ID:560
Candidate for Awards:None

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