Donald W. Hood

The influence of dietary fatty acids and environmental temperature on the fatty acid composition of teleost fish.

Marine and fresh water fish were depleted of tissue unsaturated fatty acids to various degrees and subsequently presented with linoleic and linolenic acids at different dietary levels, at different temperatures, with and without other dietary fat.Examination of the tissue fatty acids demonstrated that marine and fresh water fish do not differ between themselves or from other classes of animals in the following basic mechanisms of deposition and interconversions of dietary fatty acids:1)The fish are readily depleted of tissue polyunsaturated fatty acids.2)Dietary linoleic and linolenic acids are deposited, the former to a greater degree than the latter.3)At high levels of linoleic or linolenic acids in the diet there is no significant degree of their conversion to the longer chain more highly unsaturated acids typical of marine oils.4)At low levels of linoleic or linolenic acids in the tissues there is a significant, but slight, conversion to the longer chain acids at low environmental temperatures.5)The increase in the level of linoleic acid in tissue lipids which accompanies increases in the dietary levels, quickly tapers off above dietary levels of 5%.6)Temperature differences between 13 and 23C had little or no influence on the deposition or interconversion of polyunsaturated acids.7)Dietary cottonseed oil, which contains cyclopropene fatty acids, produces an increase in tissue stearic acid in the fundulus.

The fatty-acid content of ocean water

Abstract A method is described for relatively rapid identification of fatty acids derived from sea water. A concentrated extract was obtained by solvent extraction, the methyl esters were prepared, and the samples were analysed by gas-liquid chromatography. The results show the presence of lauric, myristic, palmitic, stearic, myristoleic, palmitoleic, oleic, linoleic, linolenic and other trace components. The fatty acids showed marked changes in relative amounts of the individual acids with depth of water, deep water having almost no unsaturated acids and a tendency toward shorter-chain acids.

Recovery of dissolved organic matter in sea-water and organic sorption by particulate material

Abstract A brief discussion on some initial data concerning organic matter dissolved in sea-water and its adsorption on particulate material is given. Various methods of isolating dissolved organic matter, its effect on the buffer system and on calcium carbonate solubility are discussed. In addition some data on the fatty acid content of sea-water is given. The studies on the sorption of organic material on suspended sedimentary particles indicate a functional relationship of mineralogy and organic type.

Benzene synthesis by low temperature catalysis for radiocarbon dating

Abstract A method is described for the ambient temperature synthesis of pure benzene from acetylene in 50–60 per cent yields that is suitable for low-level liquid scintillation counting. Application of this method to carbon dating essentially eliminates previous problems encountered in the use of liquid scintillation counting for this purpose. The method extends the sensitivity of the carbon dating method and yet requires only standard commercially available counting systems.

The effect of diet on the fatty acid composition of several species of fresh water fish

SummaryFour kinds of fresh water fish were captured in the young stage, maintained on a low-fat diet for about two months, and either continued on that diet or transferred to test diets containing 10% cottonseed or menhaden oil for about five weeks. The fish were then sacrificed, and their total body fatty acids were examined for relative amounts of 2, 3, 4, 5 and 6 double bonds. It was found that no significant change from the natural diet occurred in the fatty acids on the low-fat or cottonseed oil diets while on the menhaden oil diet the fatty acid composition changed to resemble the composition of that oil.These changes differed from those of the marine mullet in that the body fat of the latter lost much of its naturally occurring polyunsaturated acids, when placed on the low-fat regimen, and regained it on the menhaden oil diet.

The origin and metabolism of marine fatty acids: the effect of diet on the depot fats of Mugil cephalus (the common mullet).

It appears that young mullet make excellent experimental fish for dietary studies. They are hardy, easily caught, resistant to disease, and take well to aquaria conditions. Of particular interest, they may be fed synthetic food and they resist changes in salinity well. These experiments indicate that, on a fatfree diet, the mullet does not synthesize the large amounts of polyunsaturated fatty acids normally found in its body fat. However the mullet, like land animals, can apparently convert dienoic acid from cottonseed oil into small amounts of tetraenoic, pentaenoic, and hexaenoic acids. Unlike land animals, the mullet appears to be capable of the conversion of linoleic acid to a trienoic acid. Finally, when fed a diet containing a typical marine fat such as menhaden oil, the mullet stores it almost unchanged.

Boron-boric acid complexes in sea-water

Abstract Boron in the Gulf of Mexico, in the forms of total, inorganic and organic complexes, was evaluated using a mannitol titrometric method. Definite correlation between inorganic boron and chlorinity was observed for sea water, both vertically and horizontally, except in the oxygen minimum region. Similar, but less-defined correlation, is found to exist between the organic boron complexes and oxygen distribution. A preliminary investigation using boron-chlorinity ratios for identification of water masses and possible detection of circulatory patterns was made on the deep water of the Caribbean. Data from the Venezuela, Columbia, Cayman, and Gulf basins all showed conservative boron-chloride ratios. Analysis of the data indicates a uniformity of deep basin waters of the American Mediterranean Sea, which suggests the existence of a single source of deep water or uniform mixing between the basins.

The origin of the marine polyunsaturated fatty acids. Composition of some marine plankton

Summary and ConclusionsShrimp, crabs, the marine diatomNitzschia closterium, Platymonas sp., and the fresh water algaChlorella pyrenoidosa were maintained or cultured in the laboratory. The crustacea were fed low-fat, cottonseed oil, and menhaden oil rations. The fatty acid composition of all groups, as well as that of native phytoplankton and zooplankton catches, were determined as the extinction coeffcients, (E1%1cm.), at wavelengths of maximum absorption.It was found that both shrimp and crabs lost much of their polyunsaturated acids on the fat-free diet and regained it again by ingestion, as do fish. The shrimp however appeared to synthesize more highly unsaturated acids from cottonseed oil than did other aquatic animals.Phytoplankton do produce a high level of polyunsaturated fatty acids.The importance of the determination of the structure of aquatic plant and animal fatty acids in the problem of the origin of the acids and their mechan ism of synthesis was discussed.