The influence of age on the sensitivity of the Guppy (Lebistes reticulatus), to X-rays
Dickinson, Ronald Charles
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Four basic age groups of the Guppy, (Lebistes reticulatus), were exposed to 1500R, 2500R, and 3500R X-rays to determine the influence of age on the lethal effect of X-rays. Also, incidental studies of the effects of X-rays on pregnant females, fractionated dose, LD₅₀₍₃₀₎ determination, and observation of gross radiation injury were included. It was found that the radiosensitivity of the guppy increases from the age of two months to the age of four months. However, the two week old fish are slightly more sensitive than the two month old fish. Exposure of pregnant females to 1500R X-rays reduced the birth rate from an average of 15.2 to 9.2 individuals per delivery. The existence of a recovery phenomenon after exposure to a fractionated dose was inconclusive. The LD₅₀₍₃₀₎ of the two week old guppy was found to be 3306. 4R, two month - 3461.9R, three, month - 2946.2R, and four month - 2592.2R X-rays.