Studies of the orientation of the mitochondrial redox carriers. III. Orientation of the gx and gy axes of the hemes of cytochrome oxidase with respect to the plane of the membrane in oriented membrane multilayers.

The EPR absorption properties of the hemes of cytochrome oxidase and their liganded derivatives were examined in oriented multilayers from isolated oxidase, mitochondrial membranes and membrane fragments of a bacterium, Paracoccus denitrificans. The hemes of the oxidase in all the systems investigated were oriented normal to the plane of the multilayers. The directions of the g signals corresponding to the gx and gy axes of the g tensor were found to be different in low-spin ferric heme in fully oxidized oxidase and in half-reduced liganded oxidase. It is suggested that this different orientation of gx and gy in fully oxidized oxidase and half-reduced liganded oxidase arises because the respective EPR signals belong to two different hemes, those of cytochrome a and a3.     

Solubilization of microsomal phosphoethanolaminetransferase by octyl glucoside

Phosphoethanolaminetransferase of high specific activity was solubilized from rat liver microsomes with the non-ionic detergent octyl glucoside. The solubilization method is fast and simple, allowing for processing of large amounts of material. The solubilized enzyme is stable. It contains virtually no phosphocholinetransferase activity. A preliminary characterization of the enzyme, with both diacyl- and alkylacyl-glycerol as substrate, is given. For the reaction, the lipid substrates were incorporated into artificial phospholipid bilayers (liposomes).     

Structures and fatty acid compositions of neutral glycosphingolipids of human plasma

Major neutral glycosphingolipids were isolated from human plasma and their structures and fatty acid compositions studied. The four neutral glycosphingolipids of plasma were characterized as Glc beta(1 leads to 1)ceramide, Gal beta(1 leads to 1)- ceramide, Gal beta(1 leads to 4) Glc beta (1 leads to 1)ceramide, Gal alpha(1 leads to 4) Gal beta(1 leads to 4) Glc beta(1 leads to 1)ceramide and GalNAc beta(1 leads to 3) Gal (1 leads to 4) Gal (1 leads to 4) Glc beta(1 leads to 1)-ceramide. The glycosphingolipids contained mostly short chain fatty acids of which most prominent was C16. Erythrocyte glucosylceramide and lactosylceramide exhibited similar fatty acid compositions as their plasma counterparts. Triglycosylceramide and globoside of erythrocytes contained almost exclusively long-chain fatty acids. In lactosylceramide obtained from "p" erythrocytes, an accumulation of long-chain fatty acids was found; this accumulation was not observed, however, in lactosylceramide isolated from "p" plasma. It was concluded that plasma and erythrocyte glycosphingolipids are synthesized at separate sites where short- and long-chain fatty acids, respectively, are available. Plasma and erythrocyte glucosylceramide, and probably a fraction of lactosylceramide, exchange between plasma and erythrocyte pools. The latter conclusion is discussed in the light of the relative roles of carbohydrate and lipid moieties of the glycosphingolipids in maintaining their association with erythrocyte membranes.     

RS virus components. II. Antigenicity.

Rabbits were immunized with RS virus components, isolated as described previously. The sera were tested by neutralization, double diffusion and complement-fixation. RS virus components induced low titers of precipitating and complement-fixing antibodies, and failed to stimulate the neutralizing antibodies.     

Ultrastructural localization of cytoplasmic phosphatases in preimplantation mouse embryos.

The appearance and localization of the cytoplasmic phosphatases [acid phosphatase (AcPase) as a marker of lysosomes, TPPase as a marker of the Golgi apparatus, and NDPase (IDPase) as enzymatic marker of the endoplasmic reticulum (ER)] were cytochemically studied on the ultrastructural level in secondary oocytes and in preimplantation mouse embryos. The detectable AcPase activity, located on the inner surface of the membrane delimiting some cytoplasmic vacuoles (lysosomes and autophagic vacuoles), appears at the eight-cell stage and grows pregressively stronger up to the blastocyst stage. Golgi-associated reaction for TPPase was detectable in oocytes, dropped in one-cell embryos and became negative in the two-cell embryos. The reaction for TPPase and IDPase was present in plasma membranes of oocytes and early embryos and appeared in the delimiting membrane of some cytoplasmic vesicles in eight-cell embryos. Some activity of IDPase was found in small segments of the ER at the morula and blastocyst stage. The observed results suggest that the lysosomes are the first organelles in early embryos showing activity of the marker enzymes of the phosphatase type, while the activity of other marker enzymes is mainly concentrated in the plasma membrane of blastomeres. It cannot be excluded, however, that positive reaction for TPPase and IDPase in the plasma membrane results from nonspecific action of other phosphatases.     

Studies on metabolic activity of planktonic bacteria isolated from three lakes.

Studies were carried out on metabolic activity of 480 bacterial isolates on 9 substrates. All bacterial isolates studied except one utilized the casamino acids. Also with casamino acids the highest oxygen uptake values were obtained. Among the carbohydrates, glucose was most frequently utilized by the planktonic bacteria. Bacteria isolated from water of the various lakes differed in their metabolic activity as well as in the capability of utilizing the individual substrates. The capability of attacking by the bacteria the substrates applied depended largely upon the time of their isolation.