The effect of feeding redfish (Sebastes marinus or mantella) oil or a derived n-3 fatty acid concentrate containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the fatty acid compositions of individual phospholipids in selected neural tissues was studied in growing male rats. Control animals were given sunflower oil in the diet for the 5-wk feeding trial. Lipid analyses revealed that EPA (20:5n-3) became significantly enriched in all phospholipid fractions (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol) in the tissues studied (brain, retina and sciatic nerve) in the two n-3 fatty acid dietary groups relative to controls. Corresponding changes were also found in the 22:5n-3 contents of these tissues, whereas little or no significant elevation in DHA (22:6n-3) was found. In contrast, the percentages by weight of the n-6 fatty acids including 18:2n-6, 20:4n-6 (arachidonic acid, AA), 22:4n-6 and 22:5n-6 were generally lower in the various phospholipids/tissues of the animals given fish oil or the n-3 fatty acid concentrate; the levels of 22:5n-6 and 22:4n-6 were markedly affected in this regard. These results indicate that dietary n-3 fatty acids (as EPA plus DHA) can greatly affect the fatty acid compositions of the various membrane phospholipids in nervous tissues within a relatively short time. These biochemical alterations may be important for functional changes including altered membrane fluidity, cellular responses, ion transport and the biosyntheses of AA- and EPA-derived prostaglandins and leukotrienes.

19963. Aspects of the energy metabolism of lake sturgeon, Acipenses fulvescens, with special emphasis on lipid and ketone body metabolism. Can. J. Fish. Aquat. Sci. 47: 873-88'1.Key enzymes in several metabolic pathways in five tissues were measured in a primitive osteichtkyan, the lake sturgeon (Acipenses fdvescens). bevels of nonesterified fatty acids (NEFAs) were measured in the plasma as an indicator of fatty acid mobilization and differential utilization of individual NEFAs as substrates for lipid oxidation. The metabolism of lake sturgeon differs from that of most teleosts studied; it has detectable levels of beta-hydroxybutyrate dehydrogenase in all tissues, possibly a primitive metabolic feature of vertebrates, subsequently lost in the telecasts. Based on HOAD and CPT activities lipid oxidation in extrahepatic tissues of sturgeon is intermediate between elasmobranch and telegast models. Sturgeon plasma NEFA concentrations are clearly higher than those detected in any elasmobranch, indicating that the acipenserid chondrosteans may be among the first jawed dish to mobilize and transport IBIEFAs. Oleic acid ('1 8:1 ,n9) which amounts to 45% sf total NEFA content of the plasma may be a preferred substrate of carnitine dependent oxidation. High levels of long chain fatty acid in the plasma may represent a high turnover of eicosanoid precursors. The low levels sf LDH in the anoxia tolerant sturgeon may indicate that alternative anaerobic end products, perhaps ethanol, are used to survive under anoxic conditions. bes principales enzymes de plusieurs voies metaboliques dans cinq tissus ont kte rnesurks dans un osteichthyen primitif, l'esturgeon de lac (Acipewses fdvescens). bes concentrations d'acide gras nonesterifiks (NEFA) ont kt@ mesurkes dans le plasma 3 titre d'indicateur de la rnobilisatican de I'acide gras et de I'utiiisation diffkrentielle de chaque NEFA comme substrats pour I'oxydation des lipides, he mktabolisrne de I'esturgeon de lac difiere de celui de la plupart des td6ostkens etudiks; ce poisson adiiche en effet des concentrations detectables de beta-hydroxybutyratedkhydrog6nase dans tous ses tissus, ce qui etait probablement une caracteristique mktabolique primitive des vertebrks, disparue par la suite chez les tkl6ostkens. D'aprGs les activites de HOAD et de CPT' l'oxydatican des lipides dans les tissus extrahktape'ques de I'esturgeon se situe h un niveau intermkdiaire entre celle des modeles elasmobranches et tklesstkens. Les concentrations plasmatiques de NEFA de 'esturgeon sont de toute kvidence plus klevkes que celles relevkes chez tous les 6/asmobranches, ce qui r6v&le que les chondrosteens acipenseridks pourraient avoir kt4 parmi les premiers pissons A m2chsires h mobiliser et h transporter les NEFA. L'acide olkique (1 $:I, n9), qui constitue jusqu'h 45 % de la teneur totale en NEFA du plasma, pourrait Stre un des substrats prkfer6s de I'oxydation like 21 la carnitine. Les fortes concentrations plasmatiques d'acides gras & langue chaine pourraient temoigner d'un fort taux de rensuvellement ...

Recent studies have indicated that pulmonary intravascular macrophages (PIMs) are a resident cell population which in structure and function resemble mature macrophages of the mononuclear phagocyte system (MPS) in various domestic species, particularly the ruminants. The ultrastructural features of PIMs of the goat and calf lungs were studied by using vascular perfusion and direct airway instillation of fixatives. Staining with tannic acid as a component of paraformaldehyde-glutaraldehydebased fixative revealed the presence of an electron-dense coat on the surface of the cell membrane of the PIMs. The surface coat disappeared after heparin infusion and after enzymatic digestion with lipolytic lipase, suggesting that the surface coat was predominantly lipoprotein in nature. The lipoprotein coat was organized in the form of a linear chain of spherical globules with a consistent periodicity created by the intervening translucent space between individual globules. The surface coat was separated from the outerleaflet of the cell membrane by an empty space measuring 35-39 nm in width. P I M s possessed a significant number of coated pits and coated vesicles, the cell organelles of receptor-mediated endocytosis of lipoproteins. In concurrence with the coated pits and vesicles, microtubules, multivesicular bodies, and lipoprotein-positive vesicles were also observed. It is conceivable that PIMs are involved in lipid metabolism and are the major source of vasoactive substances, which significantly influence both the dynamics of pulmonary circulation and the surfactant turnover of the ruminant lung.

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