Chromosome translocations in turtles: A biomarker in a sentinel animal forecological dosimetry

Nonhuman organisms are being exposed to ionizing radiations at radionuclide -contaminated sites around the world. Direct methods are seldom available f or measuring biologically relevant doses received by these organisms. Here we extend biological dosimetry techniques, which are much better developed for humans and a few other mammalian species, to a nonmammalian species. Tu rtles were chosen because a long-lived animal would best serve the need for low-level, chronic exposure conditions, We chose the yellow-bellied slider turtle (Trachemys scripta), which is known to have a maximum life span of at least 22 years. As reported elsewhere, we first isolated an embryonic fi broblast cell line and constructed whole-chromosome-specific DNA libraries for chromosome 1 by microdissection and PCR. A FISH painting probe was prep ared and used to establish a dose-response curve for ionizing radiation-ind uced chromosome interchange aberrations in turtle fibroblasts. This was com pared to the dose response for human fibroblasts treated under similar cond itions in our laboratory. With respect to induction of chromosome interchan ge aberrations, human fibroblasts were approximately 1.7 times more sensiti ve than the T. scripta fibroblasts. To the extent that symmetrical intercha nges are persistent over long periods, this approach could eventually provi de a measure of the integrated lifetime dose these organisms receive from r adionuclides in their environment and give a measure of the extent of relev ant genetic damage over that time, (C) 2000 by Radiation Research Society.