ω10-Lipoxygenase products of α-linolenic acid are esterified to phospholipids inHydra vulgaris

We have recently reported the occurrence of 9(R)-hydroxy-, 9(R)-hydroperoxy- and 9-keto-octadeca-10E,12Z,15Z-trienoic acids (9-HOTrE, 9-HPOTrE and 9-KOTrE) inHydra vulgaris, and their biosynthesis from -linolenic acid (-LA) through the action of an enantioselective 10(R)-lipoxygenase (10-LO). Here we describe the finding of these -LA metabolites as esters to the 2-position of phosphatidylcholine, phosphatidylethanolamine and, in trace amounts, phosphatidylinositol. Small amounts of a compound co-eluting with an authentic standard of 9(R)-hydroxy-octadeca-10E,12Z-dienoic acid, a metabolite potentially derived from the action of 10-LO on linoleic acid, were also found esterified with phospholipids. Since direct peroxidation of membrane lipids has been described, experiments were aimed at establishing whether -LA metabolite-containing phospholipids could originate, inH. vulgaris, from either spontaneous or 10-LO-catalyzed oxidation of phospholipid-bound -LA. Incubation of either unlabelled or radiolabelled PUFA-containing phosphoglycerides withH. vulgaris 10-LO did not result in their peroxidation. This suggests that -LA and LA metabolites are incorporated into glycerophospholipids after their formation by 10-LO, and that, as in mamals, membrane phospholipids may serve as a reservoir for these bioactive compounds. This is the first example in an invertebrate species of lipoxygenase products esterified to phosphoglycerides.     

Physiological importance of ω-3/ω-6 polyunsaturated fatty acids in man. An overview of still unresolved and controversial questions

Summary The essentiality of (-6) and (-3) fatty acids in mammals is well known. Nevertheless, some important points remain unclear concerning their implication in physiology. After a short discussion about the definition of essential fatty acids deficiency, this brief overview deals with some of these points, pointing out some of the unresolved questions. Different subjects are approached concerning the (-6) and (-3) fatty acids metabolism: desaturases, eicosanoids, production, as well as some of their metabolic effects on cell membranes, intestinal function, glucose and lipid metabolism, haemorheology.     

Über einen Cortison-äquivalenten Katalysator der Autoxydation der Linolsäurein vitro

Summary Acetophenone derivatives with a cortisone-like side chain have been investigated for their catalytic effect on the autoxydation of linolenic acid.-Hydroxy-acetophenone and the substituted-hydroxy-3,4-dimethoxyacetophenone are the substances with the simplest structure having a catalytic effect quantitatively and qualitatively similar to that of cortisone.The significance of substituents in the ring for the catalytic activity of the side chain is discussed.     

Hydra vulgaris ω10-lipoxygenase is used in vivo to synthesize new α-linolenic acid metabolites

Previous studies conducted in cytosolic extracts of the freshwater hydrozoanHydra vulgaris led to the finding of an abundant 11(R)-lipoxygenase catalyzing the peroxidation of polyunsaturated fatty acid (PUFAs) on the tenth carbon atom from the aliphatic end (10 peroxidation). Here we describe experiments aimed at identifying the actual metabolites generated in vivo by such enzymic activity. Homogenates ofH. vulgaris polyps were analyzed by HPLC. This showed the presence of three major components chromatographically identical to three metabolites obtained when incubating the homogenates with exogenous -linolenic acid (-LA). The presence, in extracts of polyps prelabelled with [¹⁴C]--linolenic acid, of radioactive metabolites displaying the same chromatographic properties, substantiated the hypothesis that the natural products isolated in vivo are derived from -LA. Gas chromatographic analyses revealed that this was the most abundant PUFA in both free and phosphoglyceride-bound fatty acid pools. [¹H]-NMR analysis of the endogenous substances, carried out in comparison with products obtained from exogenously incubated -LA, indicated that their structures were those of 9-hydroxy-, 9-hydroperoxy- and 9-keto-octadeca-10E-12Z-15Z-trienoic acids (9--HOTrE,-HPOTrE and-KOTrE).Hydra homogenates transformed 9--HPOTrE partly into 9--HOTrE and partly into 9--KOTrE. Chiral phase HPLC conducted on 9--HOTrE established that this metabolite was composed mostly of theR anantiomer. These observations, and the finding that the presence of exogenous arachidonic acid in incubated homogenates significantly reduces the production of -LA metabolites, provide strong evidence that these compounds are produced by an enzymic activity identical to the previously-describedH. vulgaris (R)-10-lipoxygenase. Further experiments suggested that -LA, acting as the native substrate for this enzyme, is mainly esterified on the 2 position ofHydra phosphoglycerides, and that the production of the -LA metabolites described here for the first time from natural sources, can be potentially enhanced in vivo by stimuli activating phospholipase A₂.     

A new solution of the equilibrium equation for an isothermal gas sphere

Zusammenfassung Eine neue Lösung der Gleichgewichtsgleichung in der (, )-Ebene wurde für eine isotherme Gaskugel gefunden.     

Chromosomes and giemsa-bands of the Idaho spotted ground squirrel,Spermophilus brunneus (Howell)

-Spermophilus brunneus . , 13 18 ,S. brunneus S. townsendii mollis (2n=38) , , ; ;S. brunneus . S. brunneus , Spermophilus.

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Supported by National Science Foundation Grants No. GB32114X and No. GB 29131X, and the Sprague Foundation. We thankD. Pozin for technical assistance.     

Correlation between sensitivity to trypaflavine and DNA base composition in mutants ofBacterium paracoli 5099

Bacterium paracoli 5099 , , .     

G-band patterns as chromosomal markers,and the interpretation of chromosomal evolution in wild sheep (Ovis)

- . Ovis musimon (2n=54) O. orientalis (2n=54) - - -O. canadensis mexicana (2n=54) O. musimon x O. canadensis ₁₂ - . ₂ 27 . - .

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Supported by National Science Foundation Grant no. GB 32114X and the Sprague Foundation. We thank Dr. T. C. Hsu for assistance in making the chromosome preparations and for advice and encouragement. The Trustees of the Rachelwood Wildlife Research Preserve generously allowed the biopsy of specimens of their custody. Mr.Arthur Popham kindly provided the specimens from Iran while Dr.R. M. Robinson obtained biopsies from the desert sheep.     

Mass spectrometric determination of the amino acid sequence in cystine- and cysteine-containing peptides

, - , , S-- S- .     

The role of the pentose-phosphate pathway in adjustment of the heart to a high load and the development of myocardial hypertrophy

, , - - - . .     

Contribution to the X-ray diffraction methods for precision determinations of polycrystal lattice parameters

. . : , . u-, .     

Chromosomes and some issues of the evolution of the ground squirrel genusCitellus (Rodentia: Sciuridae)

Citellus (s. str.) relictus, C. dauricus C. pygmaeus (2=36, NF=72). . (Colobotis) erythrogenys . fulvus -. . (Urocitellus) undulatus (2n=32, NF=64) . columbianus. Citellus, , Citellus, . , .     

Topochemical approach to the structure-activity relation. Retroenantio-Gly5,10-gramicidin S

, . , -Gly^5,10- , Gly^5,10- .     

The synthesis of jaceidin

Zusammenfassung Durch Kondensation nachAllan-Robinson wurde aus 2,4,6-Trihydroxy-3, -dimethoxy-acetophenon das 4-Benzyloxy-5,7-dihydroxy-3,6,3-trimethoxyflavon dargestellt. Entbenzylierung in C-4-Stellung führte zum 5,7,4-Trihydroxy-3,6,3-trimethoxyflavon. Die Eigenschaften dieser Verbindung und ihre Derivate sind identisch mit dem ausCentaurea jacea L. isolierten Jaceidin bzw. seinen Derivaten.     

Studies on rII region of T2L phage

rII T2L , rII T4B. rII T2L rII T4B. T2L rII T4B.     

A study of the mechanism of polymyxin M inactivation

.I.NH₄OH , N N - - ,-. , .     

The stimulating action of gastrin pentapeptide and histamine on adenyl cyclase activity in rat stomach

, 3',5'-, in vitro . , , 3',5'- HCl .     

Mass spectrometric determination of the amino acid sequence in peptides: Desulfurization of sulfur-containing peptides

, N- 20 - .     

Suppression of antibody formation against sendai virus in the SV40 and adenovirus 16 infected hamsters

SV₄₀ 16. 9 . . .