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Mitotic non-conformity in Aspergillus: successive and transposable genetic changes

Published online by Cambridge University Press:  14 April 2009

J. L. Azevedo  and
J. A. Roper
J. L. Azevedo
Affiliation:
Department of Genetics, The University, Sheffield S10 2TN
J. A. Roper
Affiliation:
Department of Genetics, The University, Sheffield S10 2TN
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Summary

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Strains of Aspergillus nidulans with, a duplicate chromosome segment are mitotically unstable; in addition to phenotypically improved variants, arising following deletions in either duplicate segment, they give morphologically deteriorated types, some with, enhanced stability. In one isolate, deterioration and increased instability were determined by mutation in a duplicate segment; a more stable derivative no longer had this mutation but had one in another linkage group. Another variant, too unstable for analysis, gave derivatives whose single, new mutations were in different linkage groups. It is proposed that deterioration and increased instability result from tandem duplications on either duplicate segment; transposition of these to non-duplicated regions reduces instability. Another 17 variants had a single new mutation each; mutations, possibly clustered, occurred in all linkage groups. In these strains perhaps transposition preceded analysis. Deteriorated variants gave lineages of types with morphological changes caused by further, superimposed mutations. This continued instability is explained as interaction, in fidelity of replication, of non-homologous chromosome segments.

Instability in A. nidulans stems from chromosome imbalance. As imbalance is known or suspected in other cases of instability it may be possible to show common mechanisms for apparently diverse phenomena.

Type
Research Article
Information
Genetics Research , Volume 16 , Issue 1 , August 1970 , pp. 79 - 93
Copyright
Copyright © Cambridge University Press 1970

References

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