CHARACTERIZATION OF NINE TYPES 



OF RIBONUCLEOPROTEIN IN THE CELL 



BY THE TOLUIDINE BLUE-MOLYBDATE STAIN 



R. LOVE and R. G. SUSKIND 

 Laboratory of Pathology, National Cancer In sti tu te, Bethesda 14, Maryland 



Differential staining by toluidine blue-molybdate dépends upon: a),Differ- 

 ences in the susceptibility of araino groups of nucleoproteins to inactiva- 

 tion by formaldehyde and nitrous acid. b) Binding of toluidine blue by the 

 phosphoryl groups of nucleic acids at pH 3-0. c) Production of a meta- 

 chromatic toluidine blue-polymolybdate complex at some sites of dye- 

 binding. During the course of inactivation of protein-bound amino groups 

 three différent stages of staining by TBIVl hâve been produced and seven 

 types of ribonucleoprotein (RNP) hâve been demonstrated. Very short 

 fixation results in a fourth stage of staining in which two further forms of 

 RNP are recognizable. The nine forms of RNP differ in morpbology, in 

 staining properties and in functional behavior. There are two forms of 

 diffuse cytoplasmic and of chromosomal RNP; one form is unaltered while 

 the other undergoes cyclical changes during mitosis. Peri-chromosomal 

 and granular cytoplasmic RNP, granular and amorphous parachromatin and 

 the RNP of the pars amorpha of the nucleolus ail undergo a séries of chan- 

 ges in mitosis. The granular and the amorphous parachromatin appear to be 

 functionally différent; both are extrachromosomal in the interphase nucleus, 

 increase in amount during prophase, are liberated into the cytoplasm at 

 the onset of metaphase and are not included in the telophase daughter 

 nucleus. The granular form disperses freely into the entire cytoplasm at 

 the end of prophase. The amorphous parachromatin diffuses only into the 

 spindle area and may constitute an RNA template for the formation of the 

 protein of the spindle fibres. Colchicine prevents the diffusion of amor- 

 phous parachromatin into the spindle zone. 



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