Cyclopropenoid fatty acids (CPFA), which are a group of
fatty acids produced by plants of the order Malvales, are known
to induce adverse physiological effects when administered to a
variety of animal species. A structurally strained cyclopropene
ring is present in all CPFA and is believed responsible for the
toxic action of these fatty acids. Dietary consumption of CPFA
by mammals, poultry and fish has resulted in toxic responses
including hepatic damage, impaired reproductive capabilities and
sizeable alterations in lipid metabolism. Furthermore, CPFA
have been identified as mildly carcinogenic and strongly
cocarcinogenic towards rainbow trout (Salmo gairdneri). The
mechanism by which CPFA enhance carcinogenesis is currently not
understood. The research in this thesis has therefore been
directed toward obtaining a better understanding as to how CPFA
induce toxic responses in rainbow trout.
Hepatic plasma membranes were isolated from both control
trout and trout which had consumed dietary CPFA. The plasma
membranes were then compared via the use of electron microscopy,
chromatographic analysis of phospholipid and fatty acid
content, two dimensional polyacrylamide gel electrophoresis of
proteins, and Western blot analysis of concanavalin A sensitive
glycoproteins. Electron micrographs revealed that control
plasma membranes appeared more homogeneous than CPFA membranes
and were characterized by more membrane sheets and less
vesicularization. The analysis of enzyme activities revealed
that CPFA caused a decrease in whole liver glucose-6-phosphatase
activity and that control plasma membranes expressed slightly
higher glucose-6-phosphatase and 5'-nucleotidase activities as
compared to CPFA membranes. Although dietary CPFA appeared to
have no effect on the phospholipid content of the plasma
membranes, significant alterations in the fatty acid profiles
of ethanolamine and choline phospholipids were observed. CPFA
caused a decrease in palmitic, palmitoleic and oleic acids while
the level of stearic and docosahexaenoic acids subsequently
increased. Differences between the protein content of control
and CPFA plasma membranes were made clear through the analysis
of electrophoretic and Western blotting data. Membranes
isolated from fish fed CPFA contained several proteins of high
molecular weight (above 66,000 daltons) and other proteins of
high isoelectric point that were not present in control plasma
membranes. Additionally, two families of glycoproteins which
had previously been identified as microsomal in origin were detected only in CPFA plasma membranes. A discussion concerning the possible causes and biological ramifications of
the observed subcellular alterations caused by CPFA insult is
also presented in this thesis. / Graduation date: 1989
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27223 |
| Date | 31 October 1988 |
| Creators | Marino, Donald R. (Donald Robert) |
| Contributors | Selivonchick, Daniel P. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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