Summary
A diploid strain of Aspergillus nidulans with two heteroallelic mutations in the pabaA cistron (right arm of the first chromosome) has been studied. Part of the paba-independent colonies which have been examined was heterogeneous, i.e. they showed conidia of different colour and genotype. The genetic analysis of the various type of these heterogeneous colonies leads to the conclusion that, in Aspergillus nidulans, mitotic intragenic recombination is, in most cases, consequence of a single-strand break and exchange followed by the formation of a very long hybrid-DNA region (in our case a maximum of 22 meiotic units); the selected characteristics arise mainly by gene-conversion.
Furthermore, data show a high negative interference between the selected crossing-over and a second crossing-over on the left arm and probably also on different chromosomes. The latter exchange occurs, as the former, between subchromatidic units.
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Bandiera, M., Armaleo, D. & Morpurgo, G. Mitotic intragenic recombination as a consequence of heteroduplex formation in Aspergillus nidulans . Molec. Gen. Genet. 122, 137–148 (1973). https://doi.org/10.1007/BF00435187
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DOI: https://doi.org/10.1007/BF00435187