Iodine-131 metabolism in Pheretima hawayana (Rosa, 1891)

Abstract

Iodine-131, carrier free, was injected into the celoma of the earth-worm, Pheretima hawayana (Rosa, 1891). Individual measurements were made of radioactivity at different times after the injection, thus allowing the ploting of a retention curve of iodine. By this procedure a plateau starting at 48 hours was observed. By this method iodine distribution was studied in animals 48 hours after the isotope administration. A net accumulation was seen between somites 21 to 50. On the other hand the greatest concentration was in the intestine corresponding to the same region (anterior intestine). It was also established that the concentration of radioactivity in the celomic fluid is very low, and mainly due to iodide. Radioactivity was homogeneously distributed through the body. Radioiodinated compounds were studied by paper chromatography of hydrolizates of the animals after butanol extraction. The presence of diiodotyrosine was observed utilizing two different systems of solvents. It has to be pointed out that the same results were seen when Iodine-131 was administered externally, by placing the animals in a solution containing the isotope.