The marine dinojlagellates Prorocentrum micans, Gonyaulax polyedra, Gymnodinium sp., and Alexandrium tamarense, collected from the Adriatic Sea during red-tide blooms, were cultured to investigate the 4-methy l sterol constituents. To ascertain a possible influence of cell age on the 4-methyl sterol content, for one strain (Gymnodinium sp.) we investigated the composition of these constituents at exponential and stationaly growing phases. The lipid material extracted with acetone from the lyophilized algal samples was fractionated by thin-layer chre matography. The 4-methyl sterols recovered from the layer were converted into the corresponding OTMS derivatives. Nine of 11 constituents were identified by gas chromatography and gas chromatography-mass spectromet?y; only two minor constituents were characterized by their gas chromatographic parameters. All free methyl sterols identzjied in the algal samples had been detected previously in various dinoflagellates. The 4-methyl sterol fractions generally

Our studies on the biochemical composition and the structural organization of smooth and rough endoplasmic reticulum isolated from Morris hepatomas 9618A and 3924A confirm the results obtained employing the total microsomal fraction. We have definitely established the following facts: (1) Tumor subcellular organelles exhibit the very low degree of peroxidizability that has been shown to be related to the growth rate of the tumor. (2) Associated with such a low susceptibility to peroxidation are (a) changed lipid composition of cellular membranes, whose content in polyunsaturated fatty acid is markedly decreased, and (b) changed static and dynamic properties of the membrane. Previously it was also found that cellular oxy-radical scavenging enzymes are markedly reduced. From these data, it is possible to infer that tumor membranes are altered structurally and functionally in part as the result of an oxy-radical-induced damage that occurs in vivo under conditions of oxygen toxicity. This seems to be supported by recent findings that the spontaneous increase in growth rate of the originally very slow-growing Morris hepatoma 9618A results also in the loss of cytochrome P-450 (an important intramembraneous propagator of lipid peroxidation) as well as of C20:4 and C22:6. Studies performed by GLC and GC-MS on the fatty acid residues of phospholipids of rat liver microsomes show the presence of C20:3-OH and C18:1-OH, but no hydroxyl derivatives of low molecular weight aldehydes. The hydroxyl derivatives of arachidonic acid and linoleic acid are present in much smaller amounts in the microsomes isolated from H9618A and H3924A.

No abstract

No abstract

No abstract