Sucrose labeled, uniformly

Fig. 10.21. Comparative analysis of nucleolar preribosomes by electrophoresis and sedimentation. Cells were labeled for 30 min with ( H)uridine (0.3 /jCi/ml, 1.2 /iM uridine, 4 x 10 cells/ml) and nucleoli prepared from which the preribosomes were extracted. A) one part of these preribosomes with some cytoplasmic ribosomes as markers were analysed by electrophoresis on a 2.2% uniform polyacrylamide gel B) Another part was analysed by sedimentation on a 5-20% sucrose gradient in EDTA-buffer...

The USPNF 23 describes sugar spheres as approximately spherical granules of a labeled nominal-size range with a uniform diameter and containing not less than 62.5% and not more than 91.5% of sucrose, calculated on the dried basis. The remainder is chiefly starch. 

Uniformly labeled D-glucose, D-fructose, and sucrose are prepared by photosynthesis using an appropriate plant and isotopic carbon dioxide 248), Similarly, uniformly labeled D-galactose is obtained by photosynthesis with C 02 and the red alga Irideae laminarioides, where it occurs as a 2-glycerol D-galactopyranoside (65). 

Contrary findings have been reported in which the percentage as well as the total content of cholesterol in the liver of rats were appreciably less for starch- than for sucrose-fed animals (Adams et at, 1959). No alteration in the amount of cholesterol esters was found in the livers of rats during 12 weeks on high-sucrose, fructose, and dextrose diets (Macdonald and Roberts, 1965) and, though the dietary carbohydrate was uniformly labeled with very little incorporation was found in the sterol esters in the liver. Thus there seems to be uncertainty about the effect of dietary carbohydrate on the amount of cholesterol, free or combined, in the liver and the confused results probably reflect the influence of the other components of die diet. 

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