Nitrogneous waste products and excretory enzymes in the marine polychaete Cirriformia spirabrancha (Moore, 1904)

Abstract

1. 1. Cirriformia spirabrancha primarily excretes ammonia, along with trace amounts of urea and taurine. No amino acids were found to be excerted. 2. 2. Studies of uricase, allantoinase, allantiocase and urease suggest that the ammonia primarily results from a uricolytic pathway. 3. 3. The presence of ornithine transcarbamylase, argininosuccinate lyase, arginase and citrulline in the tissues strongly suggests a functional ornithine-urea cycle. 4. 4. Glutamine-like labile amides present in the greatest amounts in the tissues associated with excretion support the idea that amino acid deamination may also play a role in the formation of ammonia. 5. 5. The rate of ammonia excretion in this sedentary polychaete is relatively constant. 6. 6. The ammonia level of the aqueous gut contents is very low, which suggests that there is enteronephric excretion. 7. 7. The most probable sites of excretion are the tentacles and, to a lesser extent, the anterior body wall, which contains a single pair of large nephridia. This hypothesis is supported by biochemical assays done on the tissues, by behavioral studies and by descriptive anatomy of the nephridia. 8. 8. Following inanition, the levels of ammonia and urea drop markedly in the tissues associated with excretion and maintain their levels in the tissues associated. with the bulk of the catabolic machinery.