Effect of polar lipids on ATPase activity of membrane preparations from germinating radish seeds

Membrane preparation (sedimenting between 13,000_g and 80,000_g) of germinating radish seeds (Raphanus sativus L.) was active in hydrolyzing ATP and, to a lesser extent, a variety of other phosphorylated compounds. Dicyclohexylcarbodiimide (DCCD) and diethylstilbestrol significantly inhibited the ATPase activity (40%) while their effect on hydrolysis of other phosphorylated compounds was much less.     

Biological activity of a polar lipid of Clostridium butyricum spores

A fraction of polar lipids was isolated from spores of the anaerobic bacterium Clostridium butyricum 35/11 exerting a noticeable radioprotective effect. The main biological activity of spore extracts was associated with this fraction. The fraction of polar lipids inhibited autolysis of the bacterial cell walls. The fraction was found to contain a phenolic glycolipid and a peptide component. The bacteriostatic and radiotherapeutic properties of the fraction are presumed to be due to its membranotropic activity.     

Structural and physicochemical properties of polar lipids from thermophilic archaea

The essential general features required for lipid membranes of extremophilic archaea to fulfill biological functions are that they are in the liquid crystalline phase and have extremely low permeability of solutes that is much less temperature sensitive due to a lack of lipid-phase transition and highly branched isoprenoid chains. Many accumulated data indicate that the organism’s response to extremely low pH is the opposite of that to high temperature. The high temperature adaptation does not require the tetraether lipids, while the adaptation of thermophiles to acidic environment requires the tetraether polar lipids. The presence of cyclopentane rings and the role of polar heads are not so straightforward regarding the correlations between fluidity and permeability of the lipid membrane. Due to the unique lipid structures and properties of archaeal lipids, they are a valuable resource in the development of novel biotechnological processes. This microreview focuses primarily on structural and physicochemical properties of polar lipids of (hyper)thermophilic archaea.     

Chlorosome lipids from Chlorobium tepidum: characterization and quantification of polar lipids and wax esters

We have extracted polar lipids and waxes from isolated chlorosomes from the green sulfur bacterium Chlorobium tepidum and determined the fatty acid composition of each lipid class. Polar lipids amounted to 4.8 mol per 100 mol bacteriochlorophyll in the chlorosomes, while non-polar lipids (waxes) were present at a ratio of 5.9 mol per 100 mol bacteriochlorophyll. Glycolipids constitute 60 % of the polar lipids while phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, and an aminoglycosphingolipid make up respectively 15, 3, 8 and 12 %. A novel glycolipid was identified as a rhamnose derivative of monogalactosyldiacylglycerol, while the other major glycolipid was monogalactosyldiacylglycerol. Tetradecanoic acid was the major fatty acid in the aminoglycosphingolipid, while the other polar lipids contained predominantly hexandecanoic acid. The chlorosome waxes are esters of unbranched fatty acids and fatty alcohols with 14 or 16 carbon atoms, joined to form molecules with between 28 and 32 carbon atoms. The stoichiometry between lipids and bacteriochlorophyll suggests that much of the chlorosome surface is covered by protein.     

Bioactive polar lipids from Chroococcidiopsis sp. (Cyanobacteria)

Many studies indicate that various bioactive metabolites subsist in cyanobacteria. Glycolipids of cyanobacteria are reported as molecules that exert specific bioactivities. In this study, total lipids of Chroococcidiopsissp., a coccoid cyanobacterium isolated from a Greek cave, were separated into neutral and polar-lipids and the latter were further fractionated by high-performance liquid chromatography (HPLC). Each polar lipid fraction was tested in vitro for its ability to inhibit platelet-activating factor (PAF)- and thrombin-induced washed rabbit platelet aggregation and/or to cause platelet aggregation. The structures of the most active fractions were elucidated by biological assays and identified by electrospray mass spectrometry. One fraction was a potent inhibitor of PAF-induced platelet aggregation. Structural studies of this fraction indicated the existence of phospho-glyco analog of ceramide. Another fraction that was a potent inhibitor of PAF- as well as of thrombin-induced platelet aggregation was structurally elucidated as a phospho-acetylated glyco-analog of diglyceride. The fraction that induced platelet aggregation was identified as a phospho-acetylated-glyco analog of ceramide. These novel bioactive polar lipids in cyanobacteria in regard to the structure and biological activity may contribute to the allergic character of cyanobacteria.     

产甲烷细菌的极性脂质结构

古细菌的极性脂质是以植烷醇结构为特征的,它有别于真细菌和真核生物的正常脂质。构成产甲烷细菌极性脂质的基本骨架有四种:阿克醇、卡克醇、马克醇和海克醇。本文阐述了各种产甲烷细菌极性脂质成分的结构;从这些脂质成分的结构特点上看,或许极性脂质可作为系统分类和进化的标志。     

Comparison of two methods for the separation of polar from nonpolar lipids

The countercurrent extraction method of Galanos and Kapoulas for the separation of phospholipids from triglycerides was compared with dialysis in petroleum ether in an apparatus modified from that of Eberhagen and Betzing. The efficiencies of the methods are similar, but dialysis, which is slower, can yield triglycerides that are entirely free from phosphorus. The behavior of free fatty acids and monoglycerides is also described.     

Physical properties of liposomes and proteoliposomes prepared from Escherichia coli polar lipids

Reconstituted proteoliposomes serve as experimental systems for the study of membrane enzymes. Osmotic shifts and other changes in the solution environment may influence the structures and membrane properties of phospholipid vesicles (including liposomes, proteoliposomes and biological membrane vesicles) and hence the activities of membrane-associated proteins. Polar lipid extracts from Escherichia coli are commonly used in membrane protein reconstitution. The solution environment influenced the phase transition temperature and the diameter of liposomes and proteoliposomes prepared from E. coli polar lipid by extrusion. Liposomes prepared from E. coli polar lipids differed from dioleoylphosphatidylglycerol liposomes in Young's elastic modulus, yield point for solute leakage and structural response to osmotic shifts, the latter indicated by static light scattering spectroscopy. At high concentrations, NaCl caused aggregation of E. coli lipid liposomes that precluded detailed interpretation of light scattering data. Proteoliposomes and liposomes prepared from E. coli polar lipids were similar in size, yield point for solute leakage and structural response to osmotic shifts imposed with sucrose as osmolyte. These results will facilitate studies of bacterial enzymes implicated in osmosensing and of other enzymes that are reconstituted in E. coli lipid vesicles.     

Structures of polar lipids from the thermophilic, deep-sea archaeobacterium Methanococcus jannaschii

Cells of Methanococcus jannaschii, grown at 65 degrees C in a defined medium, contained 7% of lipid composed of 87% polar and 13% neutral components. Within the polar fraction 16 lipids were resolved by thin-layer chromatography, 4 of which were present in trace amounts. Staining reactions demonstrated that the more abundant lipids were glycolipids, aminophospholipids, and an aminophosphoglycolipid. Most of the polar fraction (82%) consisted of five diether lipids, which were purified and their structures were resolved largely through nuclear magnetic resonance, mass spectrometry, and optical rotation methods. Macrocyclic diethers had the head groups phosphoethanolamine-(1----6)-beta-D-glucopyranose, beta-D-glucopyranose, and beta-D-glucopyranosyl-(1----6)-beta-D-glucopyranose. Phosphoethanolamine was identified as a head group for both the noncyclized and macrocylic diether core lipids. The neutral lipids were mainly acyclic C30 isoprenoids, predominantly dihydro-, hexahydro, and octahydro-squalenes.     

Phase transitions in liposomes formed from the polar lipids of mitochondria from chilling-sensitive plants

The thermal response of mitochondrial polar lipids from a variety of chilling-sensitive and chilling-insensitive plants was determined by differential scanning calorimetry. A phase transition was observed at 15°C for mitochondria from soybeam (Glycine max. cv Davis) hypocotyl, at 16°C for tomato (Lycopersicon esculentum cv Flora-Dade and cv Grosse Lisse) fruit, at 15°C for cucumber (Cucumus sativus L.) fruit, at 14°C for mung bean (Vigna radiata var Berken) hypocotyl, and at 15°C for sweet potato (Ipomea batatas L.) roots. The transition temperature was not significantly altered by the scan rate and was reversible. Changes in the temperature coefficient of motion for a spin label, intercalated with the polar lipids, occurred at a temperature slightly below that of the phase transition, indicating that the polar lipids phase separate below the transition. No phase transition was observed for mitochondrial polar lipids from barley (Hordeum vulgare) roots, wheat (Triticum aestivum L. cv Falcon) roots, and Jerusalem artichoke (Helianthus tuberosus L.) tubers. The results show that a phase change occurs in the membrane lipids of mitochondria a few degrees above the temperature below which chilling injury is evident in the sensitive species. Thus they are consistent with the hypothesis that sensitivity to chilling injury is related to a temperature-induced alteration in the structure of cell membranes.     

Aliphatic alcohol sulfates: new polar lipids isolated from various Fucacea]

Four new sulfolipids have been found in the three Fucacea from the coast of Britany P. canaliculata (L) Deen et Thur, F. vesiculosus (L), F. serratus (L). These four polar lipids form a separate group, their structures being very different from those of the glyceride by-products already known. By acid hydrolysis of these substances the aliphatic mono and dialcohols can be separated. The aliphatic hydrocarbons studied by gas chromatography and spectrometric methods (IR, MASS), have been established as being saturated C30 mono or dialcohols, saturated C18 and C20 monoinsaturated dialcohols. SAA are the only substances found: there was no sulfonate or phosphate ester in the three algae studied. The quantity and composition of SAA are not characteristic of the species. Their variations depend on the physiological and biochemical states of the thallus and on the conditions of extraction and purification.     

Biological activity of lipids and photosynthetic pigments of Sargassum pallidum C. Agardh

The biological activity of lipids and photosynthetic pigments of the kelp Sargassum pallidum (Turner) C. Agardh has been studied. Free fatty acids and their esters demonstrated considerable antimicrobial activity against bacteria (Staphylococcus aureus and Escherichia coli), yeast-like fungi (Candida albicans), and opportunistic pathogenic (Aspergilius niger) and phytopathogenic (Fusarium oxysporum, and Septoria glycines) fungi. Glyceroglycolipids and neutral lipids demonstrated moderate activity. Fucoxanthin and chlorophylls weakly suppressed the growth of microorganisms. None of the studied substances demonstrated activity against Ehrlich’s carcinoma. It was shown that the season of weed harvesting affected both antimicrobial and hemolytic activities of different lipids due to changes in their fatty acid composition.     

Enhanced solvent extraction of polar lipids associated with rubber particles from Hevea brasiliensis

Biochemical studies of lipids bound to rubber particles have been complicated due to the solubility of polyisoprene chains in most extracting solvents and the rather delicate nature of polar lipids that are often denatured when traditional solvent extraction techniques are employed. In this paper, we describe a traditional technique and accompanying solvents that permit optimal extraction of rubber particle bound lipids. The technique, which is validated after characterizing the lipid extracts by elemental analysis, silica column adsorption and thin layer chromatography, appeared more suitable for extracting total lipids with optimal glycolipid and phospholipid contents. This technique is proposed as an alternative to traditional extraction methods used for solid natural rubber as it offers advantages with respect to ease of application, extract quality, extraction yields and reproducibility.     

Lessons from the genomes of bifidobacteria

The gut microbiota is a complex ecosystem composed of hundreds of different bacterial species that altogether play an important role in the physiology of their host. In the past few years the complete genome sequence of a number of bacterial strains isolated from the human gastrointestinal tract has been established including that of Bifidobacterium longum NCC2705 isolated from the feces of a healthy infant. Bifidobacteria are among the first species to colonise the human gastrointestinal tract and as such are believed to play an important role in gut homeostasis and normal development. The genome sequence of NCC2705 has revealed a number of features that suggest how this bacterium has adapted to its environment and that could help understanding how it interacts with its host. Here, we review general features of bifidobacteria and illustrate how genome-based approaches can help us better understand the biology of these organisms.     

Lipidomic analysis of Toxoplasma gondii reveals unusual polar lipids

Analysis of the polar lipids of Toxoplasma gondii by electrospray ionization tandem mass spectrometry provides a detailed picture of the lipid molecular species of this parasitic protozoan. Most notably, T. gondii contains a relatively high level, estimated to about 2% of the total polar lipid, of ceramide phosphoethanolamine. The ceramide phosphoethanolamine has a fatty amide profile with only 16- and 18-carbon species. Compared with the host fibroblasts in which it was grown, T. gondii also has higher levels of phosphatidylcholine but lower levels of sphingomyelin and phosphatidylserine. Analysis at the molecular species level indicated that T. gondii has greater amounts of shorter-chain fatty acid in its polar lipid molecular species than the host fibroblasts. Shorter-chain fatty acids with a combined total of 30 or fewer acyl carbons make up 21% of Toxoplasma's, but only 3% of the host's, diacyl phosphatidylcholine. Furthermore, diacyl phosphatidylcholine with two saturated acyl chains with 12, 14, or 16 carbons make up over 11% of parasite phosphatidylcholine but less than 3% of the host phosphatidylcholine molecular species. The distinctive T. gondii tachyzoite lipid profile may be particularly suited to the function of parasitic membranes and the interaction of the parasite with the host cell and the host's immune system. Combined with T. gondii genomic data, these lipidomic data will assist in elucidation of metabolic pathways for lipid biosynthesis in this important human pathogen.     

Biological and genetic classification of canine intestinal lactic acid bacteria and bifidobacteria

To investigate the distribution of lactic acid bacteria (LAB) inhabiting canine intestines, a total of 374 gram-positive LAB and bifidobacteria (BF) isolated from large intestinal contents in 36 dogs were classified and identified by phenotypic and genetic analyses. Based on cell morphological sizes, these isolates were divided into seven biotypes containing the genera Lactobacillus, Bifidobacterium, Enterococcus, and Streptococcus. The LAB and BF isolates were classified into 38 chemotypes based on SDS-PAGE protein profile analysis of whole cells. Furthermore, partial 16S rDNA sequencing analysis demonstrated the presence of 24 bacterial species in the 38 chemotypes from 36 dogs. The identified species consisted of ten species belonging to the genus Lactobacillus (78.8%), seven species to the genus Bifidobacterium (6.8%), five species to the genus Enterococcus (11.6%), one species of Streptococcus bovis (2.0%), and one species of Pediococcus acidilactici (0.8%). In particular, the most predominant species in canine intestines were L. reuteri, L. animalis, and L. johnsonii and were found in the high frequency of occurrence of 77.8, 80.6, and 86.1%, respectively. Besides these, Enterococcus faecalis, Bifidobacterium animalis subsp. lactis, Pediococcus acidilactici, and Streptococcus bovis were also isolated in the present study. The sequences of the isolates also showed high levels of similarity to those of the reference strains registered previously in the DDBJ and the similarity was above 97.2%. Their partial 16S rRNA genes were registered in the DDBJ.