In vitro glycosylation in the retina in canine ceroid-lipofuscinosis

Dolichol-dependent glycoprotein synthesis in the sensory retina of adult dogs with canine ceroid-lipofuscinosis (CCL) has been investigated by studying 3H-mannose uptake in organ culture. Sensory retinal organ cultures were prepared from unaffected littermates and mongrel dogs were used as controls. Morphometric analysis of autoradiographs from dogs without disease showed maximal uptake predominantly into photoreceptors and inner segments, and no abnormalities of incorporation were observed in two affected animals. Tunicamycin blocked the reaction in both samples. Incorporation of 3H-leucine was also normal in CCL retinal tissues. These studies demonstrate that the pathways for addition of mannose residues into dolichol pyrophosphate prior to transfer onto acceptor proteins is similar in normal dogs and those with CCL and does not appear to be the primary lesion in ceroid formation. Its role as a model for lipopigment storage is discussed.