Supplementary Material for: Nuclear Bud Formation: A Novel Manifestation of Zidovudine Genotoxicity

Normal diploid somatic mammalian cell division generates 2 daughter cells as a result of a strict and well-controlled mitotic process. However, some defects during the progression of that process could generate an unbalanced distribution of chromosomes, aneuploidy and eventually, a malignant phenotype. Previous observations using a transgenic mouse model with diminished DNA repair capacity revealed the presence of nuclear buds (NBs) induced in vitro by the nucleoside analog zidovudine (Retrovir®, 3′-azido-3′-deoxythymidine, AZT). Here we used bone marrow mesenchymal cells, taken from mice with the <i>Xpa</i>^–/–<i>Trp53</i>^+/– genotype, that were cultured and exposed to 0 and 100 µ<i>M</i> AZT for 24 hours. Fixed and denatured cells were processed by fluorescence in situ hybridization (FISH) with whole chromosome painting probes used to identify chromosomes in cells growing on glass chamber slides (2 probes/slide). A variety of sizes and shapes of NBs were observed. Some NBs had a large connection with the main nucleus (&gt;¼ of the NB diameter), others hada smaller connection (