PRESENCE OF BETA-CITRYL-L-GLUTAMIC ACID IN THE LENS - ITS POSSIBLE ROLE IN THE DIFFERENTIATION OF LENS EPITHELIAL-CELLS INTO FIBER CELLS

The beta-CG concentration in the chicken brain was high during embryon ic development and decreased rapidly to a lower level close to hatchin g, while the concentration in the eyeball which was also high during t he embryonic life retained a fairly high level after hatching. The dis tribution of beta-CG in the bovine eye was determined. About 95% of to tal beta-CG content in the whole eye was localized in the lens. Howeve r, the distribution of beta-CG in the eye varied depending on species. beta-CG was exclusively localized in the lens in the eyes of fish and mammals, but distributed in both lens and retina in frogs. The molecu le was localized in the retina rather than the lens in the chicken eye , although the concentrations was extremely low compared to those in t he mammalian, amphibian and fish eyes. It was found that beta-CG is pr esent ubiquitously in the lens or retina in various species. The distr ibution of beta-CG in the bovine lens was determined in the three cort ex regions and nucleus. beta-CG was present at the highest concentrati on in the equatorial cortex, at a moderate concentration in the poster ior and anterior cortex, and at the lowest concentration in the nucleu s. Similar distribution patterns were also found in the rabbit and rat lens. When embryonic chick lens epithelial cells were cultured in the presence of fetal calf serum, the cells elongated, differentiated int o fiber cells and formed lentoid bodies. The cells of lentoid bodies w ere stained strongly by the anti-beta-CG antibody, while cells around the structures were not. In addition, the beta-CG content in the lense s from the galactose cataractous rat decreased to about 20-30% of that in the normal lens. These findings suggest that beta-CG may play a ro le in the differentiation of epithelial cells into fiber cells. (C) 19 95 Academic Press limited