Date of Award
1990
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Abstract
It is well known that dolichol accumulates with age in animal tissues. The mechanism of dolichol accumulation is not understood and it is unclear to what extent the accumulation of this compound affects the process of N-linked protein glycosylation.;In order to estimate the dietary contribution to body pools (1-{dollar}\sp{lcub}14{rcub}{dollar}C) dolichol was mixed in vitro with sunflower seed oil and given to rats by gavage. Less than 0.02% of the dose was found in the tissues after 12 h. The majority of the absorbed radioactivity was found in the liver at this time. There was no indication of catabolism of the dolichol backbone in either the tissues or the gut.;A procedure is described for the determination of total cholesterol, dolichol and dolichyl phosphate (Dol-P) in small samples of mammalian tissue, based on extraction of these compounds into diethyl ether after saponification of the tissue. These methods gave recoveries of over 90% for cholesterol and dolichol and about 60% for Dol-P. Extractability of Dol-P is affected primarily by the concentration of KOH in the saponification mixture.;A procedure described for in vivo metabolic labelling of polyisoprenoids using tritiated water. Unlike other precursors, tritiated water equilibrates rapidly with the body water to generate a single pool which has a constant specific activity over the duration of most experiments. The problems of differences in precursor pool size between tissues and physiological states are thus avoided.;Metabolic labelling experiments using tritiated water demonstrated that the synthesis of total dolichol (dolichol + Dol-P) in the kidneys did not change as a function of age. The data suggest that the primary age-associated change in dolichol metabolism may be a change in the relative activities of dolichol kinase and Dol-P phosphatase.;The capacity of the tissues to synthesize N-linked glycoproteins, based on the amount of Dol-P found in the microsomes, as a function of age was assessed. The amount of Dol-P in the microsomal fractions isolated from the kidneys and liver of mice increased with age suggesting an increase in the capacity for N-linked glycoprotein synthesis in these tissues. Observed levels of dolichol and Dol-P in the microsomes from the kidneys and liver were consistent with an alteration in the relative activities of dolichol kinase and Dol-P phosphatase.
Recommended Citation
Crick, Dean Calvin, "Age-associated Changes In Tissue Dolichol And Dolichyl Phosphate Content And Metabolism" (1990). Digitized Theses. 1879.
https://ir.lib.uwo.ca/digitizedtheses/1879