Rosette grain

Rosette Grain. See under Cannon Propellant or Cannon Powder in Vol 2, C30-R to C31-L... 

Incubate the reticulocytes with [3H]leucine, which will be incorporated into proteins. Prepare electron microscope autoradiographs and count silver grains per cell and the number of polysomes. The latter appear as rosettes of five ribosomes in these cells. A statistical comparison between the number of polysomes and the amount of protein synthesized during the incubation time (proportional to the number of silver grains) indicates whether there are nonactive polysomes. In fact, many of the polysomes are inactive i.e., they are switched off (see Chap. 17 for the control of protein synthesis). 

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