The present paper provides very welcome evidence for the mechanism responsible for tandem duplications resulting from Ac/Ds transposition. To provide more historical context it might have been worth citing the work of Jonathan Jones and colleagues (1). Jones addressed two alternative mechanisms for aberrant transposition as the single chromatid substrate (SIN) and the sister chromatid substrate (SIS) models. They concluded that although the majority of the rearrangements were consistent with the SIS model, others were consistent with the SIN model addressed in the current paper. Jones attributed the alternative models to Starlinger (1984) and Fedoroff (1989), respectively.


1. English, J.J., Harrison, K. and Jones, J.D.G. (1995) Aberrant transpositions of maize double Ds-like elements usually involve Ds ends on sister chromatids. The Plant Cell, 7, 1235-1247.