| In studying the aging of the free-living soil nematode Caenorhabditis elegans, six quantitative age-dependent parameters have been identified and characterized. These parameters are movement wave frequency, defecation frequency, as well as acid phosphatase, (beta)-N-acetyl-D-glucosaminidase, (beta)-D-glucosidase, and (alpha)-D-mannosidase activities per animal. In contrast, acetylcholinesterase, choline acetyltransferase, and (alpha)-D-glucosidase activities per animal are age-independent. The two distinct rates of {lcub}('3)H{rcub}(,2)O efflux exhibited by C. elegans, and the proportions of {lcub}('3)H{rcub}(,2)O exhibiting these two rates, are also age-independent.; Populations of C. elegans, N2, cultured at 20(DEGREES)C, or C. elegans, DH26, cultured at 25.5(DEGREES)C, exhibit an age-dependent, four-fold linear decline in population mean movement wave frequency, and a 25-fold multiphasic decline in population mean defecation frequency. In longitudinal studies, individual animals exhibited linear declines in movement wave frequency and multiphasic declines in defecation frequency; however, there was no correlation between the rate of decline in movement or defecation and an individual's lifespan. For C. elegans, DH26, cultured at 25.5(DEGREES)C, acid phosphatase, (beta)-N-acetyl-D-glucosaminidase, (beta)-D-glucosidase, and (alpha)-D-mannosidase activities per animal increase continuously from early adulthood through mid-life. Subsequently, activity levels remain relatively constant, except (alpha)-D-mannosidase, which decreases rapidly with age.; All four age-dependent hydrolase activities are glycoproteins, have acidic pH optima, and equilibrate at 1.15 and 1.20 gm/cm('3) following isopycnic centrifugation. These results strongly suggest that acid phosphatase, (beta)-N-acetyl-D-glucosaminidase, (beta)-D-glucosidase, and (alpha)-D-mannosidase are lysosomal enzymes. Furthermore, although ion exchange chromatography separates multiple forms of acid phosphatase and (beta)-D-glucosidase activities, one chromatographic form of each activity was primarily responsible for the age-dependent increase in total activity. The amount of acid phosphatase I activity per animal increases 18-fold, while (beta)-D-glucosidase I activity per animal increases 100-fold.; The age-dependent changes in movement wave frequency, defecation frequency, acid phosphatase, (beta)-N-acetyl-D-glucosaminidase, (beta)-D-glucosidase, and (alpha)-D-mannosidase are sufficiently large and reproducible to be useful as quantitative markers of the senescence of C. elegans. |
