Proteoglycan distribution pattern during aging in the nematode Caenorhabditis elegans:: An ultrastructural histochemical study

Glycosaminoglycans are important constituents of the extracellular matrix of vertebrates, where distinct changes in their distribution pattern occur during aging. However, little is known about their changes in the nematode Caenorhabditis elegans, which ages extremely rapidly compared to mammals. The presence of glycosaminoglycans was analysed in cross-sections of all organs of the nematode, in three different age groups (60, 144, 228 h), using the electron-dense dye Cuprolinic Blue in conjunction with the critical electrolyte concentration method and specific glycosaminoglycan degrading enzymes. The nematodes (strain DH 26) were grown at 25.5 degrees C. The results indicate the presence of an organ-specific distribution pattern. Chondroitin-4-sulphate and/or chondroitin-6-sulphate are present in the epicuticula. Chondroitin-4-sulphate and/or chondroitin-6-sulphate and dermatan sulphate are detected in the mesocuticula. If stained by conventional methods the mesocuticula shows an empty fissure, which is filled by chondroitin sulphates and dermatan sulphate as shown by Cuprolinic Blue staining and enzymes. Heparan sulphate is found in the terminal web of intestinal cells while dermatan sulphate is revealed in the central cores of microvilli. An unknown polyanion staining at high electrolyte concentrations is observed in the gonads. Age-related changes do not impair the composition of the glycosaminoglycan fraction. In conclusion an unexpected highly differentiated pattern of glycosaminoglycans with high stability during aging exists.