Mutations in rDNA. 2. Effects of Actinomycin D on chromatid aberration induction in nucleolus organizer regions

Abstract

A reconstructed karyotype of barley with all chromosomes interdistinguishable was treated with hydroxyurea (HU) and Actinomycin D (Act D). The distribution pattern of chromatid aberrations after treatment with HU alone is characterized by a marked preferential involvement in chromatid translocations of segments 36 (NOR of satellite chromosome 6) and 43 (NOR of satellite chromosome 7). Act D applied at the low concentration of 0.05 μg/ml (4.10(-8) M) before HU treatment, or combined with HU, was found to cause an apparent decrease of HU-induced aberration frequencies in NORs. The exchanges in both segments proved to be approximately a half lower after Act D application when compared to the respective controls (treatment with HU alone). A recovery period of 5 h between the prolonged pretreatment with Act D (15 h) and the HU treatment eliminated the effect of the drug. The possible dependence of mutation induction upon the transcriptional activity of rDNA in NORs after Act D application is discussed.

In Vivo Genotoxic Effects of Spiramycin in Rat Bone Marrow Cells.

“…Genotoxic effect of these antibiotics were determined by various test systems (CA test, micronucleus test, SCE investigations and so on). These effects are as follows: Broken chromosome, micronucleus, various translocations, X-linked gene mutation in Drosophila, pause of meiotic division, dominant lethal mutations and SCEs (Promchainant 1975, Mace Jr. et al 1978, RaskO et al 1979, Meiying et al 1982, Nicoloff et al 1982, Richardson et al 1984, Singh and D'Ambrosio 1984, Sora et al 1984, Clements et al 1990, Hayashi et al 1990, Mavournin et al 1990, Odagiri et al 1990, Roselli et al 1990, Koldamova and Lefterov 1991, Miller 1991, Nersessian et al 1991, Risley and Pohorenec 1991, van Pelt et al 1991, Sudman et al 1992, Aboul-Ela 1995, Hoffmann et al 1995. These antibiotics have caused chromosomal and gene mutations due to direct effect on DNA.…”

“…For example, Actinomycin D has induced interchromosomal translocation at the Nucleoler Organizer Region in barley and increased the micronucleated polichromatic erythrocytes (PCE) in mouse bone marrow cells (Nicoloff et al 1982, Mavournin et al 1990. Adriamycin has increased the number of chromosomal aberration (CA) and micronucleus (MN) in Chinese hamster ovary (CHO) cells, in vivo mouse bone marrow cells, secondary spermatocyte and spermatid of,Xenopus laevis (Mace Jr. et al 1978, Mavournin et al 1990, Risley and Pohorenec 1991.…”