Radiation induction of multiaberrant cells in Allium cepa L. N.K. Kutsokon 1, 2 , N.M. Rashydov 1 and D.M. Grodzinsky 1 1 Dept. of Biophysics and Radiobiology, Institute of Cell Biology and Genetic Engineering NAS of Ukraine, Zabolotnogo, 148, Kyiv, 03680 Ukraine, 2 Dept. of Molecular Genetics and Biosafety, National Agricultural University, Geroiv Oborony, 13, Kyiv, 03041, Ukraine, kutsokon@univ.kiev.ua Abstract. “Rogue” cells determined by human geneticists as the cells with many chromosome aberrations. The main enigma of this phenomenon is its levels are unexpected higher in many studies. Frequently, these cells emergence in human are linked with radiation or viruses. “Rogue” cells supposed to be very important in mutagenesis, oncogenesis and even in evolution process. We use plant assay (Allium cepa L.) to analyze the induction of cells with many chromosome aberration of different types. Cytogenetic damage of gamma-irradiation as frequency of multiaberrant cells in the root tip cells of Allium was determined. The empiric numbers of cells with many aberrations were compared with those expected in theoretical distributions (Poisson, geometric and Pascal). The frequency of multiaberrant cells in root tip cells was increased up to 83,33 ± 10,76 % under gamma- irradiation in various doses. Gamma-irradiation induced more multiaberrant cells in A. cepa meristems than expected in theoretical distributions. We supposed dependency of chromosome aberrations origin in the same cell after irradiation. The data obtained elucidate that under gamma-irradiation accumulation of aberrations in aberrant cells are not random, the appearance of one aberration in cell induced the appearance of others in the same cell. 1. INTRODUCTION Bloom and colleagues [1] are supposed to be the first to have determined and described in details the rogue cells in human in 1970s. “Rogue” cells were recognized as “containing five or more exchange-type aberrations for which precise karyotypic identification of the origin of the aberrant chromosomes usually was impossible” [2]. Such cells were later determined in different groups of people classified as control ones as well as those exposed to radiation or chemical factors [3-15]. The absence of the relation between doses of mutagenic factors and levels of rogue cells is frequently emphasized in such works. So, in spite of high level of rogue cells in people exposed to radiation, researchers not always consider the irradiation as a main cause of such cells [16-19]. In observation [20] grossly departing of damaged cells per individual from a Poisson distribution was determined. Actually, rogue cells in most cases are very rare that is why it is difficult to distinguish the spontaneous and mutagen-induced levels of rogue cells. Correlations determined between the high frequency of rogue cells and the level of malignancy in various population groups [21-24] and between the high frequency of other chromosome abnormalities in individuals with rogue cells [2, 12] was revealed. There is no special experimental confirmation on the nature of rogue cells inductor but a few hypotheses are proposed. The most popular of them are hypotheses on viral origin of rogue cells [23] and their induction by high-LET particles irradiation [16-18, 25]. Furthermore it is supposed that emergence of rogue cells is due to “in its own way “infectious process” then emergence of one aberration in cell may favorably induce others aberrations” [26], trouble of the cell cycle and apoptosis control [27], action of bacterial restriction endonucleases [28]. But all this hypotheses and suppositions are not always satisfactory for explaining the nature of rogue cells therefore it seems that they “may be the result of a combination of rare events of different undetermined nature” [29]. Though the mechanisms of exclusion of rogue cells