(full paper is archived in the Miller Library)
Title: The pathways of nitrogen excretion in Littorina planaxis
Student Author(s): Moulton
Location: Final Papers Biology 175H
Date: June 1964
Abstract: 1. An account is given of the experiments designed to elucidate the sources and modes of formation of the excreted urea, uric acid, and ammonia in the marine gastropod Littorina planaxis. 2. It is suggested that arginase is not concerned with the production of ureas in the members of this species because no correlation ws found between the amount of urea and arginase activity. In the production of ureas and ammonia, which represent the principal nitrogenous end products of the Littorines, the enzyme arginase is not of significant importance. 3. Xanthine ocidase is shown to present in the kidney of this snail, though hitherto, it has not been found in other marine invertebrates (Baldwim and Needham, 1934). It is suggested that this enzyme maybe responsible for formation of uric acid in Littorina planaxis and other members of this group, whether the uric acid is derived ultimately from nucleic acid greakdown or from protein deamination. 4. The uricotelic character of the metabolixm of this gastropd is supported by the presence of urease, uricase, and xanthine oxidase in the kidney tissue and indicate a mechanism which can account for most of the nitrogen excretory products.