Studies on the larval salivary gland of drosophila. III. The Histochemical localization and possible significance of ribonucleic acid, alkaline phosphatase and polysaccharide at the University of Kansas

Evidence recently presented by Moog and E. Wenger ( '52) shows that in the tissues they examined, a neutral mucopolysaccharide is associated with cytoplasmic sites of high alkaline phosphatase activity. They propose the hypothesis that this phosphatase-associated mucopolysaccharide may constitute a dynamic enzyme-orienting cytoskeleton essential for the enzymatic activity. Bradfield ('50) found an inverse relationship between the site of high alkaline phosphatase activity and the localization of ribonucleic acid in silk glands. He suggests that the phosphatase may be part of the enzyme system involved in the liberation of newly synthesized protein from a complex with nucleic acids. The possible connection between polysaccharide, alkaline phosphatase and ribonucleic acid makes the study of these substances within an active protein synthesizing cell extremely interesting and of prime importance. Such a cell can be found in the larval salivary gland of Drosophda robusta. During most of the comparatively long larval period the salivary gland is both a growing and a secreting organ. Toward the end of the larval stage it undergoes a rapid metamorphic