A pedigree analysis of several cell-colony generations following a mutagenic treatment with nitrous acid has shown that in S. pombe a genetic instability is produced that replicates several times and produces a mutation in independent lines.
It has been shown that the mutants isolated in the progeny of a mosaic colony all contain a genetic alteration that cannot be resolved by genetic analysis and therefore the mutations have occurred at the same genetic site. This finding is confirmed by interallelic complementation and phenotypic analyses.