D. J. Lee

The effect of dietary sterculic acid on the hepatic lipids of rainbow trout.

Groups of young rainbow trout (5 g) were fed a basal diet containing 9% salmon oil and 1% tristearin with 0, 100 or 200 ppm methyl sterculate. Liver lipids were separated into polar and nonpolar fractions and the fatty acids quantitatively analyzed. Significant elevations of the stearic-oleic and the palmiticpalmitoleic ratios were found in liver fatty acid composition 10 days after the feeding trial began. Liver triglycerides of fish fed methyl sterculate for 87 days contained only 2–3% docosahexenoic acid as compared to 10.69% in control trout, suggesting an effect on the biosynthesis of long chain polyunsaturates. Dietary cyclopropenoid fatty acids (CPFA) suppressed growth rate during the first part of the 200 day feeding trial. After 90 days no differences in the rate of weight gain were observed between the control and CPFA groups. A seven day feeding trial with 0, 5, 20, 50 and 100 ppm CPFA resulted in a maximum change in the stearic-oleic ratio at 50 and 100 ppm levels. All levels of CPFA increased this ratio and caused marked alterations in the cellular morphology of the liver.

Acute toxicity of aflatoxins B1 and G1 in the rainbow trout (Salmo gairdneri)

Abstract Nine-month-old Mt. Shasta strain rainbow trout averaging 60 g each were used to determine the median lethal doses (LD50) of aflatoxins B1 and G1. The toxins were isolated from cultures of Aspergillus flavus (ATCC 15517) grown on rice. Statistical treatment of mortality occurring during the 10-day period after intraperitoneal injection of the mycotoxins gave LD50 values of 0.81 mg/kg and 1.90 mg/kg for aflatoxin B1 and G1, respectively. Trout given oral doses of aflatoxins, or those given an LD50 ip dose, regurgitated their stomach contents. It is suggested that acute toxicity studies of aflatoxins given by the oral route in this manner are not practical in the case of the rainbow trout.

Cholesterol levels, atherosclerosis and liver morphology in rabbits fed cyclopropenoid fatty acids**

Abstract Male New Zealand rabbits were fed diets containing either 0.27% cyclopropenoid fatty acids (CPFA) or 0.5% cholesterol or both in combination. Compared with control animals, those receiving CPFA tended to have higher plasma- and liver-cholesterol levels and a higher incidence of aortic atherosclerosis. A similar pattern was seen when animals fed cholesterol and CPFA were compared with animals fed cholesterol alone. The observed increases in liver cholesterol, plasma cholesterol and plasma triglycerides indicated a wide range of sensitivity to CPFA. Some animals had plasma-cholesterol levels eight to ten times as high as normal after feeding had continued for 3 wk, while others showed only slight changes after 5 wk. Liver cells from all CPFA-fed animals had altered morphology and often showed extensive damage.

Mass spectra of methyl sterculate and malvalate and 1,2-dialkylcyclopropenes☆

Abstract The mass spectra of 1,2-dipropyl-, 1,2-dipentyl-, 1,2-dihexyl-, 1,2-diheptyl-, and 1,2-dioctyl-cyclopropene, methyl malvalate, methyl sterculate, malvalyl alcohol, 1,2-dipropyl-, 1,2-dipentyl-, and 1,2-dihexylcyclopropene-3-carboxylic acid, and methyl-9,10-(carbethoxymethano)-9-octadecenoate are presented. A noticable feature of the 1,2-disubstituted cyclopropene spectra is the total absence of a cyclopropenium ion. The cyclopropenes with a carboxyl group in the 3-position yield cyclopropenium ions in the mass spectra. β-Cleavage to a allylic ion appears to be important.

Liver composition and histology of rainbow trout fed cyclopropenoid fatty acids

Rainbow trout were fed 200 ppm cyclopropenoid fatty acids (CPFA) in a semipurified casein-gelatin-dextrin diet for 8 months. Liver weights, liver fat, and glycogen levels were measured during the course of the exepriment and compared with those of control fish. The effect of CPFA on liver histology was also monitored and was found to produce necrosis of hepatocytes, unusual glycogen deposition, appearance of “fibers” in the cytoplasm of many cells, and fibrotic bile ducts and blood vessels. Most of these histological abberations remained after MS was removed from the diet. Liver size, expressed as a percentage of body weight, in CPFA-fed fish became significantly larger (P < 0.05) after 7 months and remained higher until the feeding trial was terminated. Percentage of liver lipids was significantly higher (P < 0.05) in CPFA-fed fish, but returned to normal when the fish were returned to control diet.

Deposition of cyclopropenoids in the tissue lipids of rainbow trout fed methyl sterculate

Groups of young rainbow trout were fed diets containing 0, 100 and 200 ppm methyl sterculate. Their tissue lipids were analyzed for cyclopropene content using the modified Halphen test. Halphenpositive compounds, calculated as sterculic acid, accumulated in all tissues analyzed and reached concentrations approximately equal to those of the dietary lipid. Gas liquid chromatography used in conjuction with mild hydrogenation of the cyclopropene ring revealed that these Halphen-positive compounds were predominantly, if not entirely, sterculic acid which was esterified in the triglycerides. To facilitate analysis of cyclopropenes in liver tissue, a method was developed whereby interfering pigments were removed prior to the Halphen test.