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Genotoxicity of Adduct Forming Mutagen Benzo(A)Pyrene in Tradescantia B

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Genotoxicity of Adduct Forming Mutagen Benzo(A)Pyrene in Tradescantia B PL9700249 10 Section VII 3. A. Cebulska-Wasilewska, S. Macugowski, H. Pluciennik, R. Smoliiiski. Report IFJ No 1511/B, 7-27, 1990; 4. A. Cebulska-Wasilewska, J. Smagala, Raport IFJ No 1511/B, 53-63, 1990; 5. W. Wajda, A. Cebulska-Wasilewska, (in Polish), in: Are Chemicals More Hazardous to Environ- ment than Radiation?, Ed.: A. Cebulska-Wasilewska, Raport IF.] No 1511/B, 63-Hl, 1990; 6. A. Cebulska-Wasilewska, J. Huczkowski H. Pluciennik, (in Polish), in: Are Chemicals More Ha- zardous to Environment than Radiation?, Ed.: A. Cebulska-Wasilewska, Raport IF.J No 1511/B. 93-98, 1990; 7. A. Cebulska-Wasilewska, H. Pluciennik, A. Wierzewska, E. Kasper, B. Krzykwa, Annual Rep. 1NP, Cracow, p. 311-313 (1992); 8. A. Cebulska-Wasilewska, H. Pluciennik, A. Wierzewska, Proc. of Conf. on Env. Mutagenesis in Human Populations at Risk, Cairo, p. 41 (1992); 9. E, Carbonell, N. Xamena, A. Creus, R. Marcos, Mutagenesis 8, 511-517 (1993); 10. J. Major, G. Kemeny, A. Tompa, Acta Medica Hungarica 49, 79-90 (1993). Genotoxicity of Adduct Forming Mutagen Benzo(a)pyrene in Tradescantia B. Paika, M. Litwiniszyn, and A. Cebulska-Wasilewska Polycyclic aromatic hydrocarbons (PAH) are present among other by-products of combus- tion processes and they are ubiquitous pollutants of our environment. Benzo(a)pyrene (BaP) belonging to this class of compounds is a widely distributed environmental carcinogen that has DNA-damaging and mutagenic properties. Mutations that are formed as a consequence of induced DNA damage are very important for the process of cancer development. Since the relationship between DNA damage and mutation fixation is not always clear, there is a need to investigate a correlation between genotoxic effects on molecular and cellular levels. DNA adducts are formed as the result of covalent binding of metabolically activated car- cinogens to the DNA molecules (1). The most essential step for DNA-adduct detection is the isolation of good quality DNA which has a high molecular weight and is RXA- and protein-free. A fast and simple method for genomic DNA isolation from stock plants of Tradescantia 4430 has been already developed. With the use of this method DNA isolation has been successfully performed for different Tradescantia tissues: flowers, leaves and roots, both fresh and frozen (2). The purity and quality of extracted DNA was sufficient for DNA-adduct detection. Samples of DNA isolated from control and benzo(a)pyrene-treated tissues were subjected to DNA-adduct analysis using 32P-postlabelling assay (3). However, preliminary data have shown only slight differences between the adduct pattern of control and treated samples. The aim of our studies was to look for the induction of mutations in relation to the DNA- adduct formation in the same test system. Therefore, we have also chosen the Tradescantia 4430 plant for mutation studies of acute and chronic exposures to BaP. Pink mutation frequency (FF). lethal mutation frequency, i.e. hair stunting (STF) and cell cycle factor (CCF) were the end points studied in Tradescantia stamen hair (TSH) assay (4). The data of acute treatment are shown in Table 1. BaP dose dependence was not observed, although the mutational effect was significant. The doubling of mutation frequency indicates the mutagenicity of the compound tested. The results of chronic treatment were very similar, and lethality (hair stunting) for both exposures was relatively low indicating that in further studies treatment time can be prolonged or BaP concentrations can be higher, and that should allow us to attain a larger uptake of carcinogen. The investigations will be continued as the possibility to perform experiments that detect DNA-adducts and mutations after chemical exposure of Tradescantia offers a powerful tool for studies of environmental mutagenesis since Tradescantia is a very sensitive indicator of genotoxic agents. PL9700250 Section VII 11 Table 1. Mean values of biological effects measured by TSH assay after acute exposure to BaP. Treatment NOH1 PF±SD STF±SD CCF Rad-equiv2 /cGy/ 20^1 1% 26340 0.352±0.130 1.136±0.474 0.37 3.1 20/^1 0.1% 27800 0.317±0.112 0.412±0.251 0.38 2.3 20//1 0.01% 22710 0.400±0.189 0.867±0.501 0.31 4.2 Control 25320 0.212±0.094 0.697±0.400 0.32 - 1 - number of scored hairs 2 - values calculated for pink mutations after subtracting of the control data References: 1. F.A. Beland and M.C. Poirier, DNA Adducts and Their Consequences, in: Methods to Assess DNA Damage and Repair: Interspecies Comparisons, Eds.: R.G. Tardiff, P.H.M. Lohman, and G.N. Wogan. pp. 29-55 (1994), Publ. by John Wiley and Sons; 2. B. Palka, U. Pich, and E. Huttner, A Fast and Reliable Method for Genomic DNA Isolation from Tra.desca.ntia. Flowers, Leaves and Roots Suitable for the Detection of DNA Adducts, (submitted to Plant Mol. Biol. Rep.); 3. R.C. Gupta, M.V. Reddy, and K. Randerath, 32P-Postlabeling Analysis of Non-Radioactive Aro- matic Carcinogen-DNA Adducts, Carcinogenesis 3, 1081-1092 (1982); 4. A. Cebulska-Wasilewska, Detection of Ambient Air Pollutants Mutagenicity with Tra.desca.ntia. Stamen Hair System, Nukleonika 33, 91-105 (1988). Radiation Damage of Mouse Skin, Lung and Kidriey after Fractionated Local X-ray Irradiation Performed with the Use of Various Schedules J. Huczkowski, B. Janiszewska, T. Janiszewski, S. Krasnowolski, K. Kulczykowska, B. Lazarska, J. Skolyszewski1, V. Svoboda2, K. Trott3, and B. Wilczyriska1 1 Centre of Oncology Maria Sklodowska-Curie Memorial Institute, Cracow, 2 St. Mary Hospital, Portsmouth, England, 3 Department of Radiobiology, University of London, London, England. In radiotherapy, before clinical use of new schedules, careful mathematical analysis using LQ model must be provided. It is needed to get information as to the total dose acceptable in the new schedule, i.e. as to the level of normal tissue damage not worse than before (using the clinically proven schedule). Such analysis must be done taking into account possible reaction of both early and late reacting tissues. The parameters needed for the LQ model calculations (a / 0 and Tl/2) could be taken from animal experiments; sometimes these parameters are available in clinical radiobiology. An alternative way is the examination of the new schedule expected for clinical use by per- forming animal experiments with this schedule and measuring the early and late damage of various animal tissues after local irradiation. Such programme of studies is performed in Cra- cow. The schedules under examination are: 10 fractions of X-ray irradiation once a day over 12 days (with a break for the weekend), 20 fractions, twice a day over 12 days (every fractions is divided into two subfractions with time intervals between them of 3 or 6 hours), and the schedule.
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