Summary
Strains of A. nidulans with a chromosome segment in duplicate (one in normal position, one translocated to another chromosome) are unstable at mitosis. During vegetative growth they produce variants which result from deletions in either of the duplicate segments.
Caffeine increased the frequency of deletions from the duplicate segments of an unbalanced haploid a) without changing the proportions of the different deletion types and b) under conditions in which there were few, if any, induced breaks in the same segments of a balanced diploid. One possible explanation is that caffeine stimulates the mechanism which, in unbalanced strains, produces replication errors leading to deletions; an alternative is that it exposes the intrinsic instability of duplication strains by preventing the repair of spontaneous replication errors.
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Roper, J.A., Palmer, H.M. & Watmough, W.A. Mitotic non-conformity in Aspergillus nidulans: the effects of caffeine. Molec. Gen. Genet. 118, 125–133 (1972). https://doi.org/10.1007/BF00267083
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DOI: https://doi.org/10.1007/BF00267083