Spin probe clustering in human erythrocyte ghosts

Summary A model has been developed for 5-nitroxide stearate, I(12,3), distribution in human erythrocyte ghosts which accurately predicts ESR spectral alterations observed with increased probe/total lipid (P/L) at 37°C. This spin probe occupies a class of high-affinity, noninteracting sites at low loading. Saturation occurs with increasing probe concentration, and, at higher loading, the probe inserts itself at initially dilute sites to form membranebound clusters of variable size. No low probe remains at high P/L where all I(12,3) clusters in a concentrated phase. This model allows determination of the dilute/clustered probe ratio, and shows that I(12,3) segregates in erythrocytes at what might otherwise be considered low P/L (e.g., 1/359). These findings validate the earlier use of empirical parameters to estimate probe sequestration in biological membranes.     

Hydrogen peroxide metabolism as an index of water stress tolerance in jute

Two species of jute plants Corchorus capsularis L. (cv. JRC 212) and C. olitorius L. (cv. JRO 632) were subjected to water stress for 2 and 4 days by withholding water. The relative water content (RWC) decreased in both plants under water stress but to a greater extent in C. olitorius . The C. olitorius seedlings also showed greater membrane injury than C. capsularis seedlings under water stress as was evident from injury index data. Water stress increased glycolate oxidase (EC 1.1.3.1.) activity more in C. olitorius than in C. capsularis . The activity of superoxide dismutase (SOD, EC 1.15.1.1.) and catalase (EC 1.11.1.6.) decreased under water stress and their decrease was higher in C. olitorius than in C capsularis . The level of hydrogen peroxide and lipid peroxidation also increased in both plants under water stress and the increase was higher in C. olitorius than in C. capsularis seedlings. Under comparable external water stress, C. capsularis seedlings showed lower membrane damage, lower H₂O₂ accumulation and lower lipid peroxidation than C. olilorius which may be taken as indicative of higher water stress tolerance capacity of the former.     

Lipids of Pinus halepensis pollen

The total lipids of Pinus halepensis pollen were separated into individual classes of neutral and polar lipids and the components of each class were identified and determined quantitatively. Free fatty acids, waxes and triacylglycerols were found as the main constituents of neutral lipids and phosphatidylcholine and phosphatidylethanolamine of polar lipids. Glycerylether derivatives were detected in neutral and polar lipid fractions. Free and esterified volatile fatty acids were also found in pollen and its neutral lipid fraction.     

A comparison of the translational diffusion of a normal and a membrane-spanning lipid in Lα phase 1-palmitoyl-2-oleoylphosphatidylcholine bilayers

We have used the fluorescence recovery after photobleaching technique to study the translational diffusion, in L phase multibilayers of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), of fluorescent derivatives of 1-palmitoyl-2-oleoylphosphatidylethanolamine (NBD-POPE) and a membrane-spanning phosphatidylethanolamine (NBD-MSPE). The latter derivative was prepared from a membrane-spanning glycerol-dialkyl-glycerol tetraether lipid isolated from the thermophilic and acidophilic archaebacterium Sulfolobus solfataricus. The translational diffusion was examined between about 15° and 45°C. It is shown that over this temperature range the translational diffusion coefficient for NBD-MSPE is 2/3 that for NBD-POPE which spans only one monolayer of the bilayer. The result is interpreted in terms of existing models for translational diffusion in lipid membranes.Abbreviations D _t translational diffusion coefficient - FRAP fluorescence recovery after photobleaching - MSPE a membrane-spanning phosphatidylethanolamine derived from a glycerol-dialkyl-glycerol tetraether lipid isolated from Sulfolobus solfataricus - NBD 4-nitrobenz-2-oxa-1,3-diazolyl - PE phosphatidylethanolamine - POPC 1-palmitoyl-2-oleoylphosphatidylcholine - POPE 1-palmitoyl-2-oleoylphosphatidylethanolamine     

Effect of cultural conditions on the lipid profile of Thiobacillus ferroxidas

The intensitive investigations on the lipid profile of Thiobacillus ferrooxidans at various culture ages suggest some correlations of the lipid constitutents with the membrane-bound iron oxidation system. Phosphatidic acid, phosphatidyl serine and phosphatidyl ethanolamine were the major polar components; hydrocarbon, triglyceride and diglyceride were the main neutral components. Major fatty acids were C_16:0, C_16:1, C_16:3, C_18:1, C_18:3, C_22:1 while C_20:1, C_20:2, C_12:0, C_14:2, C_18:0, C_18:2, C_20:0, C_22:0 were found in trace amounts which also depended upon the phase of the growth. One lipoamino acid was identified as ornithine lipid in the polar fraction. Each and every component varied to some extent at different growth phasesindicating relationship of these lipids to the iron oxidation system of the strain.     

Chemical structure of the lipid A component of Plesiomonas shigelloides and its taxonomical significance

Abstract The chemical structure of the lipid A moiety of the lipopolysaccharide of the type strain of Plesiomonas shigelloides was elucidated. It consists of a β-(1 → 6)-linked glucosamine disaccharide carrying phosphate groups at C-1 of the reducing and at C-4' of the non-reducing glucosamine. It contains a total of 6 residues of fatty acids, 2 amide-linked and 4 ester-linked. The amino groups of the backbone disaccharide are N -acylated by substituted 3-hydroxyacyl residues: at the reducing glucosamine by 3-O-(14:0)14:0; and at the non-reducing glucosamine by 3-O-(12:0)14:0.
Two residues of 3-hydroxytetradecanoic acid are linked to C-3 and C-3' of the glucosamine residues; the hydroxy groups of these ester-linked 3-hydroxytetradecanoic acids are unsubstituted. In free lipid A, the hydroxyl groups at C-4 and C-6' are unsubstituted, indicating that the 2-keto-3-deoxyoctonic acid (KDO) is linked to C-6' of the non-reducing glucosamine, as was shown with enterobacterial lipid A. The taxonomical significance of these structural details is discussed.     

Isolation and structural analysis of two lipid A precursors from a KDO deficient mutant of Salmonella typhimurium differing in their hexadecanoic acid content

The extraction, purification and structural characterization of two lipid A precursors (Ia and Ib) differing only in one hexadecanoic acid are described. Both precursors were synthesized at elevated temperatures by a new mutant of Salmonella typhimurium (mutant Ts5) which is conditionally defective in synthesis of the 3-deoxy-d-manno-octulosonic acid region of lipopolysaccharides.Both precursors were purified by repeated phenol/chloroform/petroleum ether (PCP) extractions followed by thin layer chromatography. Teh precursor preparation was free of lipopolysaccharides and phospholipids and contained less than 0.1% protein. Structural analysis which included chemical degradation procedures as well as positive ion laser desorption (LDMS) mass spectroscopy of dephosphorylated lipid A precursors showed together that precursor Ia represents a diphosphorylated glucosamine disaccharide containing two ester, two amide-linked residues of 3-hydroxytetradecanoic acid and lacks the ester-linked dodecanoic, tetradecanoic and hexadecanoic acid as well as 3-deoxy-d-manno-octulosonic acid. Precursor Ib has the same basic structure as precursor Ia, but contains in addition one mol of hexadecanoic acid per mol disaccharide which is linked to the 3-hydroxy group of the amide-bound 3-hydroxy-tetradecanoic acid of the reducing, terminal glucosamine residue.The structure of precursor Ib supports the conclusion that hexadecanoic acid incorporation occurs at an early stage in lipid A biosynthesis prior to the attachment of 3-deoxy-d-manno-octulosonic acid and/or other polar substituents.Abbreviations LDMS laser desorption mass spectrometry - KDO 3-Deoxy-d-manno-octulosonic acid - Ts5 Salmonella typhimurium mutant Ts5 - PCP phenol/chloroform/petroleum ether - H₂F₂ hydrogen fluoride This work is dedicated to Prof. Dr. Drews, Freiburg, on the occasion of his 60th birthday     

Identification of a tumor inhibitory factor in rat ascites fluid

A polypeptide which inhibits the growth of human carcinoma cells has been characterized from Novikoff rat ascites fluid. This tumor inhibitory factor co-purified with transforming growth factor activity through acid/ethanol extraction and Bio-Gel chromatography. The two activities were completely separated by reverse phase HPLC. The tumor inhibitory factor is heat stable and requires disulfide bonds for bioactivity. This factor inhibited the anchorage independent growth of the more differentiated human colon carcinoma cell lines but did not affect the less differentiated carcinoma cells. The presence of stimulatory and inhibitory activities in the same extracts suggests that the relative concentrations of these factors may be important in the control of cell growth.     

Effects of in utero and in vitro incubation on the lipid-bound fatty acids and sterols of porcine spermatozoa

Sperm-rich semen and washed porcine spermatozoa were incubated for up to 2 hr either in utero in the presence of oviduct fluid or in vitro at 37°C. Sperm lipids were extracted and separated into phospholid and neutral lipid fractions. Eleven phospholipid and five neutral lipid fatty acids were identified and quantified using GC and GC-MS. The percentage of 22:5n6, the major phospholipid fatty acid, decreased slightly but significantly during 1.5 hr of in utero incubation (41.2–38.0%), but after 2.0 hr of in utero incubation no significant difference was observed (40.0%). None of the phospholipid fatty acids changed in concentration during in vitro incubation. The mole ratio of phospholipid to phospholipid fatty acid (1.00:1.27) did not change during incubation. The levels of neutral lipid-bound 14:0 decreased (43.5% to 31.8%) and that of 18:0 increased (11.1% to 18.2%) during in utero incubation. Similar but less pronounced changes were observed during in vitro incubation. (43.5% to 36.0%; and 11.1% to 15.8%, respectively). Two major sterols, cholestrol (73%) and desmosterol (27%) were identified by gas chromatography–mass spectrometry. The mole ratio of phospholipid to sterol (2.47:1:00) did not change during incubation.     

Influence of dietary supplementation with thiamine on lead intoxication in rats

The influence of dietary supplementation with thiamine on lead (Pb) contents in blood and tissues, blood δ-aminolevulinic acid dehydratase (δ-ALAD) activity, and urinary excretion of δ-aminolevulinic acid (δ-ALA) was evaluated in male Sprague-Dawley rats. Groups of randomly selected animals were given a thiamine-deficient diet, a diet containing normal thiamine (20 mg/kg), or a thiamine-supplemented diet (50 mg/kg), along with control drinking water or water containing 100 ppm Pb, for 4 mo. Animals fed the thiamine-supplemented diet (50 mg/kg) and Pb showed decreased urinary excretion of δ-ALA and a decreased inhibition of δ-ALAD activity in blood compared to those given Pb with normal thiamine diet. The liver, kidney, and blood of rats receiving supplemental thiamine also contained significantly less Pb than the other two treatment groups given Pb-containing water. The protective effect of thiamine against Pb toxicity may be attributed to its interference with retention of the metal in body tissue, possibly resulting from the formation of excretable thiamine-lead complexes.