METHODS FOR CYTOCHEMICAL CHARACTERIZATION 



OF NUCLEAR BASIC PROTEINS AND THEIR APPLICATION 



TO PROBLEMS IN DEVELOPMENT 



D. P. BLOCH and H. Y. G. HEW 



Department of Zoology, University of Califomia, Los Angeles, Califomia 



Four types of basic nuclear proteins can be distinguished on the basis of 

 their staining characteristics. The original method of Alfert and Gesch- j 

 wind, utilizing trichloracetic acid hydrolysis of DNA and subséquent stain- 

 ing of the unmasked basic proteins with fast green at high pH's, résulta 

 in the staining of most histones, including arginine-rich histones of many 

 speftn and spermatid cells. Blocking of lysine by acetylation or by deami- . 

 nation results in the loss of staining of ail but those arginine-rich his- 

 tones of sperm and spermatids. Protamines of sperm are lost during the a- 

 bove procédures, but can be demonstrated by use of picric acid hydrolysis 

 for removal of DNA and staining with eosin at high pH's. Picric acid and 

 eosin in succession form insoluble complexes with the protamine, and the 

 latter is not bleached from the cell during staining. Picric acid hydroly- 

 sis, followed by staining with bromphenol blue urtder acid conditions, and 

 differentiation in alkaline ethanol, results in the staining of faintly basic 

 nuclear proteins in the cleaving eggs of a number of organisais. Thèse 

 "histones do not otherwise stain. The possible significance of thèse 

 findings will be discussed. ■ 



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