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Structural instability of a transgene locus in tobacco is associated with aneuploidy. [Erratum: Jan 1997, v. 11 (1), p. 167.]

Papp, I., Iglesias, V.A., Moscone, E.A., Michalowski, S., Spiker, S., Park, Y.D., Matzke, M.A., Matzke, A.J.M.
The plant journal 1996 v.10 no.3 pp. 469-478
Nicotiana sylvestris, Nicotiana tomentosiformis, Nicotiana, Nicotiana tabacum, transgenic plants, loci, aneuploidy, cytogenetics, molecular genetics, chromosomes, chromosome translocation, gene expression, isomerases, karyotyping, plant proteins, gene dosage, nucleotide sequences, genotype
This paper describes molecular and cytogenetic evidence for the instability of a transgene locus that is present on the triplicated chromosome in an aneuploid tobacco line. This instability was manifested in several ways in trisomics including a major chromosome rearrangement that was detectable cytogenetically, smaller scale DNA rearrangements that occurred both germinally and somatically, and methylation/epigenetic silencing. In a deletion derivative of the locus, DNA breakpoints were found in AT-rich regions. One of these regions binds to nuclear scaffolds in vitro, suggesting a possible role for aberrant topoisomerase II cleavage in destabilization of the locus. The implications of increased chromosome instability in aneuploids for plant karyotype evolution and human carcinogenesis are discussed.