A Histochemical Analysis of the Proteins in the Larval Fat Body of Sarcophaga Bullata

Abstract

A comparison has been made between the basic proteins of the nucleus and the cytoplasm in the larval fat body cell of Sarcophaga bullata. Basic protein was found in four regions of the cell: in the nucleolus, in association with the DNA of the nucleus, as a diffuse reticulum extending throughout the cytoplasm, and as a complement of granules distributed throughout the cytoplasm. Of these four regions only the nucleolar basic protein was apparently unaffected by the blocking reactions of deamination and acetylation when stained with alkaline fast green. The proteins of the other regions were seen to be arginine-rich, but contained a sufficient amount of lysine to be slightly affected by control procedures. The cytoplasmic granular basic protein, lysosomal in nature, and the diffuse basic protein of the cytoplasm, RNA-associated, stained in exactly the same manner as did the nuclear histone with the three techniques used for histone demonstration and with the Sakaguchi reaction. Control procedures had no effect on the intensity of the Sakaguchi reaction in any region of the cell where arginine was demonstrable. It is suggested that the term histone be reserved for DNA-associated basic protein, and that some of the non-specificity of histone staining may be resolved by applying auxiliary methods for the demonstration of acid hydrolases or associated nucleic acids.