Micronucleus: A biomarker of genotoxic damage induced in vivo and in vitro from radiation and chemical exposure

Our current study demonstrates the usefulness of the micronucleus as a biological marker of exposure and the resulting damage to the genetic material. Studies were conducted in rat lung fibroblasts and dog blood lymphocytes exposed to chemicals, ethyl nitrosourea (ENU), and methyl methanesulfonate (MMS), and radiation. Micronuclei are formed when fragments of chromosomes or whole aberrant chromosomes are produced as the result of an interaction between chemicals or radiation, and the nuclear material. The number and distribution of micronuclei were evaluated both in vitro and in vivo and provided a useful biological model of the chemical mutagens ENU and MMS showed a significant increase in the number of micronuclei in their lung fibroblasts. Primary rat lung fibroblasts exposed to radon in vitro showed a remarkable increase in the number of micronuclei. The micronucleus frequency in vitro was used as a first estimate of the dose to lung fibroblasts following in vivo inhalation exposure to 320 WLM of radon. In a dog blood lymphocyte model, the frequency of micronuclei increased as a function of x-ray exposure. Using the frequency of the sensitivity of the cells to subsequent x-ray-induced micronuclei. These studies demonstrate that micronuclei are very useful biomarkers of exposure, dose,more » and alterations in cell sensitivity.« less