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Abstract
The origin of lens albuminoid was investigated by in vivo experiments using radioisotope techniques. Autoradiographic analysis of lenses from rats injected with labeled methionine at 1 week of age showed that protein synthesis occurred throughout the lens at this age, but was most intense near the periphery. In succeeding weeks, the radioactive protein was retained within the lens. Seven weeks after injection, it was buried deep within the lens nucleus. In companion radiobiochemical studies, labeled methionine was administered to an additional group of 1-week-old rats. Half the animals were killed the following day; the remainder were killed 7 weeks later. One day after injection, practically all of the protein-bound radioactivity was in the water-soluble fraction. Seven weeks later, nearly 40 per cent was recovered in the albuminoid. These findings indicate that water-soluble lens proteins are synthesized directly from amino acids in growing lens fibers, whereas albuminoid arises through a subsequent conversion of soluble protein to an insoluble form