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The incorporation of [1-14C] mannose into hamster liver glycolipids and glycoproteins was studied in normal and vitamin A-depleted hamsters. Severely (25% weight loss) and mildly (no weight loss) deficient animals were compared to vitamin A-fed controls. The incorporation of [14C] mannose into glycolipids and glycoproteins decreased in mild and severe vitamin A deficiency by 63–90% compared to vitamin A-fed animals. These results were essentially the same whether expressed per g of wet liver, per DNA or per protein. The size of the pools of mannose, glucose and galactose and their specific radioactivity in liver were determined by gas-liquid chromatography of the boronates of the hexitols (Eisenberg, Jr, F. (1972) Methods Enzymol. XXVIIIB, 168–178) in normal and vitamin A-deficient conditions. It was found that the amount of free hexoses per g of liver was very similar in normal and vitamin A-deficient conditions. The specific radioactivities for mannose and glucose were greater in vitamin A deficiency, thus excluding the possibility that the observed severe decrease in glycopeptide and glycolipid synthesis is a reflection of a similar decrease in the specific radioactivity of the precursor pools. Quantitation of mannose in glycoprotein showed a 79% decrease in vitamin A deficiency. Specific radioactivity of mannose in glycoproteins, 20 min after injection of the label, was 187 dpm/μg of mannose in the normal and 48 dpm/μg of mannose in the vitamin A-deficient livers. It is concluded that vitamin A is necessary for the biosynthesis of liver mannose-containing glycoproteins and glycolipids.

Tracheas from normal and vitamin A-deficient rats were incubated in the presence of l -[3H]fucose and d -[14C]glucosamine to label epithelial and mesenchymal glycoproteins. The epithelium and the cartilage were separated by incubation with testicular hyraluronidase and processed separately for the preparation of glycopeptides. One major epithelial glycopeptide was doubly labeled. In vitamin A deficiency the amount of l -[3H]fucose was reduced to 33% that of the normal. The tracheal fucose-glycopeptide, in molar ratios, contained fucose 1.0, mannonse 1.0, galactose 0.4, hexasamine 4.7, and sialic acid 3.5. Sulfate was absent.

Hamsters were injected intraperitoneally with [ 14 C]mannose, [ 14 C]retinol and [ 3 H]mevalonic acid. The livers were removed, extracted with chloroform-methanol and the lipids chromatographed on DEAE-cellulose and silicic acid. The hamster liver lipid contained a component which could be labelled with mannose and mevalonic acid. The properties of this compound were in accord with it being dolichyl-mannosyl-phosphate, a possible lipid intermediate required for the biosynthesis of some glycoproteins. [ 14 C]Retinol and [ 14 C] mannose were incorporated into another phospholipid which was labile to mild alkali conditions commonly used for the preparation of dolichyl-mannosyl-phosphate. The retinol labelled compound had similar properties to in vitro prepared mannosyl-retinyl-phosphate.