Ian J. Tinsley

Rapid colorimetric determination of free fatty acids.

In 1964, a method was described for the determination of free fatty acids (FFAs) in vegetable oil. This paper describes an expansion of that work, improving the sensitivity and reproducibility of the method, as well as examination of solubilities of the copper soaps as a function of chain length and unsaturation. Involvement of the micellar structure was reviewed. Finally, a procedure is described that permits very rapid determination of FFA at the 2.0–14.0 µmol (0.5–4.0 mg oleic acid) level, and the results with several oils are given. Particular attention was given to evaluation of solvent systems which would extract the copper complexes.

A simple, sensitive method for lipid phosphorus.

A method is described for quantitatively determining lipid phosphorus with a linear range from 0.7–10.0 μg. The method is simple and rapid, requiring one stable reagent and a single extraction with 1-butyl acetate after the phosphorus is converted to inorganic phosphate by means of a perchlorate digestion. The stable complex is read at 310 nm.

THE BIOCHEMICAL ANALYSIS OF SOME ESTUARINE PHYTOPLANKTON SPECIES. I. FATTY ACID COMPOSITION12

The fatty acid composition of 10 species of estuarine phytoplankton was determined using gas‐liquid chromatography. Nine of the species were isolated from Yaquina Bay, Oregon. These species were common components of the phytoplankton of the bay. The tenth species, Isochrysis galbana, was obtained from the Culture Collection of Algae at Indiana University. The 10 organisms comprised 3 species of Chlorophyta, 1 species of Cryptophyta, and 6 species of Chrysophyta.

FATTY ACIDS IN LOTIC PERIPHYTON: ANOTHER MEASURE OF COMMUNITY STRUCTURE1

The fatty acid spectra of 6 periphyton communities developed in laboratory streams at different combinations of light intensity and current velocity were determined by gas‐liquid chromatography and silver nitrate thin‐layer chromatography. Differences in species composition of the communities apparently had no striking effect on proportions of palmitic and stearic acids, whereas concentrations of myristic, palmitoleic, oleic, linoleic, and linolenic acids and a C20:5 acid were more closely related to taxonomic differences. In general, communities dominated by blue‐green algae exhibited relatively high proportions of oleic, linolenic, and linolenic acids and low proportions of palmitoleic acid and a C20:5 acid, as compared to communities consisting primarily of diatoms. The data also indicated an inverse relationship between fatty acid redundancy and species diversity.

Distribution and identification of the fatty acids from the coho salmon,Oncorhynchus kisutch (Walbaum)

To study the fatty acids of the coho salmon, entire fish were homogenized and the total lipids extracted with methanol-chloroform. The fish ranged in size from 75 to 85 mm total length and contained from 2.1%–6.9% lipid in the tissues. Methyl esters of the fatty acids were produced with anhydrous methanol and HCl. Qualitative identification of the fatty acid methyl esters was accomplished by gas-liquid chromatography.Thin layer silver nitrate-silicic acid plates were used to separate the component methyl esters according to the number of double bonds. Location of the ethylenic groups of the unsaturated fatty acid methyl esters was established by reductive ozonolysis and identification of the aldehydes and aldehyde-esters produced. The number of carbons in the unsaturated fatty acid methyl esters was determined by hydrogenation of each of the fractions.Fatty acids found in the highest concentrations were: 16∶0, 16∶1, 18∶0, 18∶1, 18∶4, and 22∶6. Fatty acids 16∶0, 18∶1, 18∶2, 20∶5, and 22∶6, differed markedly from concentrations found in tubificid worms, the exclusive diet of the fish during the experiment.

Utilization of fatty acids by the developing steelhead sac-fry, Salmo gairdneri.

Abstract 1. 1. The fatty acid content of both the yolk and the steelhead sac-fry, Salmo gairdneri , has been studied during development. 2. 2. Losses of individual fatty acids from the yolk were proportional to the mass of the particular fatty acid present and only 18:1 showed any tendency to be retained in this compartment. 3. 3. After hatching the fatty acid composition of the sac-fry was distinct from that of the yolk. 4. 4. Certain fatty acids, 16:0, 18:0 and 22:6, were preferentially retained in the sac-fry lipids. Other fatty acids, 16:1, 18:1, 20:1 and 22:5, were retained to a much smaller extent considering the quantities available. 5. 5. It is suggested that 22:6 plays a special role in the fatty acid metabolism of the fish.

Toxicology of brominated fatty acids: metabolite concentration and heart and liver changes.

Rats were fed for 35 days diets containing 2% of either brominated corn oil (BCO), monoglyceride of dibromostearate (DBS), monoglyceride of tetrabromostearate (TBS) or a mixture of the two monoglycerides (BMG) which provided proportions of brominated acids comparable to that of the BCO. Hearts from all animals fed BCO were yellow colored and firm in texture. Myocardial cellular degeneration, mild to moderate edema and occasional small necrotic foci were observed. Hearts from animals fed DBS showed moderate edema and some slight necrosis. All diets produced an increase in lipid content of heart. Animals fed the experimental diets developed enlarged livers and showed elevated liver lipid content. The tetrabromostearate appeared to be the more active in producing these changes, in particular a severe intracellular fatty degeneration. Shorter-chain (C-16, C-14) metabolites of di- and tetrabromostearate were identified and the concentration of brominated fatty acids in heart, liver and adipose tissue determined and found to account for 80% of the bromine detected in these tissues by neutron activation analysis. TBS accumulated in liver while the highest concentration of DBS was observed in heart lipids. Although the concentrations of brominated acids in heart and liver lipids were comparable in rats fed BCO or BMG, BCO produced the more pronounced effects. This differential could be due to additional active components in BCO or to a variation in response associated with changes in the location of the fatty acid on the glycerol molecule.

Bromine content of lipids of marine organisms

Lipids were extracted from a number of organisms taken in the northern Pacific ocean and the bromine content measured by neutron activation analysis. The lipids of each species studied were found to contain bromine with concentrations ranging from ten to several hundred µg/g. The major portion of the bromine was associated with the fatty acids in Chromatographic separations; however, the presence of a number of different brominated compounds was indicated. When the fatty acids were prepared from the crude lipids by acid hydrolysis, partitioned into base, and then esterified, 60% of the initial bromine was recovered in the ester fraction. This would indicate the presence of brominated acids in marine lipids.

DDT ingestion and liver glucose 6-phosphate dehydrogenase activity—II☆

Abstract A significant correlation has been observed between the dietary level of DDT and liver glucose 6-phosphate dehydrogenase activity. A dietary level of 5 ppm DDT was sufficient to induce a significant reduction in enzyme activity. The activity of liver 6-phosphogluconate dehydrogenase was not influenced by the various levels of DDT used in these experiments. It is suggested that the ratio of the activities of these two enzymes could be used as an index of DDT stress.

An interaction of DDT in the metabolism of essential fatty acids

The growth of female rats was depressed further by the incorporation of DDT into a ration deficient in essential fatty acids (EFA). With female rats fed a ration supplemented with EFA, DDT produced a slight stimulation in growth. DDT also produced an increase in the 20∶3ω9/20∶4ω6 ratio in liver lipids of male rats fed a ration deficient in EFA. These data indicate an effect in EFA nutrition. Substantial changes in the fatty acid composition of liver lipids resulted from the feeding of DDT. The proportion of 16∶0 was decreased, while that of 18∶0 was increased. With rats on the supplemented rations an increase in the proportion of 20∶4ω6 was observed, while in the deficient rats a comparable increase was observed in the proportion of 20∶3ω9. These changes in fatty acid composition have been related to the proliferation of hepatic smooth endoplasmic reticulum induced by the DDT, and it is suggested that this effect could increase the demand for EFA by the liver, thus influencing EFA nutrition.