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A variegated position effect in Aspergillus nidulans

Published online by Cambridge University Press:  14 April 2009

A. J. Clutterbuck
Affiliation:
Department of Genetics, University of Glasgow, Glasgow, Scotland

Summary

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In mutants at the ‘bristle’ locus of Aspergillus nidulans the conidiophore remains as a stiff hypha rather than developing a vesicle, sterigmata and conidia. The brlA 12 allele of this locus has a variegated phenotype, and genetic analysis has shown that this is associated with a translocation which has a breakpoint in the map interval adjacent to the bristle locus.

The mutant phenotype is partially repaired on high-salt medium at low pH, and can also be repaired by suppressors, one of which has been mapped at a locus unlinked to brlA 12.

The mutant provides proof that variegation is due to instability of gene expression and not to mutability since brlA 12 is genetically stable and can be propagated from either conidia or sterile conidiophores, the structures formed at the two extremes of variegation, and the resulting colonies in both cases are identical to the original strain.

It has been shown by mitotic recombination that the translocation associated with the variegated mutant is a ‘simple translocation’ in which the distal half of linkage group VIII is attached to the end of linkage group III. This terminal attachment site does not appear to be damaged in any genetically detectable way.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1970

References

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