Exposures to low-level ionizing radiation: Effects on biochemical and whole-body indices of growth in juvenile brook charr (Salvelinus fontinalis)

Abstract

Exposure to ionizing radiation (IR) was used to alter gonadal growth in brook charr (Salvelinus fontinalis). To evaluate the possible effects of low-level doses of IR on future seawater adaptability of brook charr, the physiological state and growth performances of juvenile brook charr were examined for 15 months. Four groups of fish were exposed to different experimental doses of IR at the hatching stage: 0 (control), 6.2, 7.8, and 11.4 Gy. Growth in length and weight and condition factors of the irradiated groups were initially impaired compared with the control. Differences in growth were observed and were proportional to the irradiation dose. Initial growth delay in the irradiated groups was followed by compensatory growth of sufficient magnitude and duration that similar weights and lengths among all groups were reached by the end of the growth trial. Changes in the concentration of nucleic acids, protein, and water content were evaluated at three trimestrial intervals in the control and 11.4 Gy groups. DNA content was systematically found to be higher in the irradiated groups compared with the control (602.76 and 850.38 μg/g wet tissue). No difference in protein content (mg/g) in relation to fish weight was found between both groups during the freshwater growth period. Lipid analysis was performed on the final samples and was found to be significantly higher in the irradiated groups displaying catch-up growth (8.2% and 11.4% wet weight). RNA/DNA, RNA/protein, and protein/DNA were also calculated. J. Exp. Zool. 283:315–325, 1999. © 1999 Wiley-Liss, Inc.