Cytogenetic methods for measuring space radiation damage in astronaut's blood lymphocytes

A new method for chromosomal aberration dosimetry is presented here. The method is based on the induction of premature chromosome condensation in peripheral blood lymphocytes by calyculin A. When stimulated lymphocytes are incubated in calyculin A, inhibition of protein serine/threonine phosphatases induces premature chromosome condensation in the interphase chromosomes. G1, G2, and M-phase cells can be scored for chromosomal aberrations after chromosome painting. In vitro tests have been performed with cells exposed to X-rays or high-LET carbon ions. The results indicate that analysis of interphase chromosomes hybridized in situ with fluorescent probes is independent from radiation-induced cell-cycle alterations. It is also suggested that conventional metaphase analysis would not be reliable after exposure to densely ionizing radiation, when most aberrant cells are blocked in G2-phase. Advantages of this method for biodosimetry in astronauts are discussed. (author)