A universal reagent for phospholipid analysis

CFTR regulation of intracellular pH and ceramides is required for lung endothelial cell apoptosis

The functional significance of the expression of cystic fibrosis transmembrane regulator (CFTR) on endothelial cells has not yet been elucidated. Since CFTR has been implicated in the regulation of intracellular sphingolipid levels, which are important regulators of endothelial cell apoptosis in response to various insults, we investigated the role of CFTR in the apoptotic responses of lung endothelial cells. CFTR was detected as a functional chloride channel in primary lung endothelial cells isolated from both pulmonary arteries (human or mouse) and bronchial arteries (sheep). Both specific CFTR inhibition with 2-(phenylamino) benzoic acid diphenylamine-2-carboxylic acid, 5-[(4-carboxyphenyl)methylene]-2-thioxo-3-[(3-trifluoromethyl)phenyl-4-thiazolidinone (CFTR(inh)-172), or 5-nitro-2-(3-phenylpropylamino)benzoic acid and CFTR knockdown significantly attenuated endothelial cell apoptosis induced by staurosporine or H(2)O(2). CFTR(inh)-172 treatment prevented the increases in the ceramide:sphingosine-1 phosphate ratio induced by H(2)O(2) in lung endothelial cells. Replenishing endogenous ceramides via sphingomyelinase supplementation restored the susceptibility of CFTR-inhibited lung endothelial cells to H(2)O(2)-induced apoptosis. Similarly, the anti-apoptotic phenotype of CFTR-inhibited cells was reversed by lowering the intracellular pH, and was reproduced by alkalinization before H(2)O(2) challenge. TUNEL staining and active caspase-3 immunohistochemistry indicated that cellular apoptosis was decreased in lung explants from patients with cystic fibrosis compared with those with smoking-induced chronic obstructive lung disease, especially in the alveolar tissue and vascular endothelium. In conclusion, CFTR function is required for stress-induced apoptosis in lung endothelial cells by maintaining adequate intracellular acidification and ceramide activation. These results may have implications in the pathogenesis of cystic fibrosis, where aberrant endothelial cell death may dysregulate lung vascular homeostasis, contributing to abnormal angiogenesis and chronic inflammation.

FTY720 inhibits ceramide synthases and up-regulates dihydrosphingosine 1-phosphate formation in human lung endothelial cells

Novel immunomodulatory molecule FTY720 is a synthetic analog of myriocin, but unlike myriocin FTY720 does not inhibit serine palmitoyltransferase. Although many of the effects of FTY720 are ascribed to its phosphorylation and subsequent sphingosine 1-phosphate (S1P)-like action through S1P(1,3-5) receptors, studies on modulation of intracellular balance of signaling sphingolipids by FTY720 are limited. In this study, we used stable isotope pulse labeling of human pulmonary artery endothelial cells with l-[U-(13)C, (15)N]serine as well as in vitro enzymatic assays and liquid chromatography-tandem mass spectrometry methodology to characterize FTY720 interference with sphingolipid de novo biosynthesis. In human pulmonary artery endothelial cells, FTY720 inhibited ceramide synthases, resulting in decreased cellular levels of dihydroceramides, ceramides, sphingosine, and S1P but increased levels of dihydrosphingosine and dihydrosphingosine 1-phosphate (DHS1P). The FTY720-induced modulation of sphingolipid de novo biosynthesis was similar to that of fumonisin B1, a classical inhibitor of ceramide synthases, but differed in the efficiency to inhibit biosynthesis of short-chain versus long-chain ceramides. In vitro kinetic studies revealed that FTY720 is a competitive inhibitor of ceramide synthase 2 toward dihydrosphingosine with an apparent K(i) of 2.15 microm. FTY720-induced up-regulation of DHS1P level was mediated by sphingosine kinase (SphK) 1, but not SphK2, as confirmed by experiments using SphK1/2 silencing with small interfering RNA. Our data demonstrate for the first time the ability of FTY720 to inhibit ceramide synthases and modulate the intracellular balance of signaling sphingolipids. These findings open a novel direction for therapeutic applications of FTY720 that focuses on inhibition of ceramide biosynthesis, ceramide-dependent signaling, and the up-regulation of DHS1P generation in cells.

Free radical fragmentation of cardiolipin by cytochrome c

The effect of cytochrome c (cyt c) on degradation of cardiolipin in its polar part was investigated in cardiolipin/phosphatidylcholine (CL/PC) liposomes incubated with cyt c/H(2)O(2)/and (or) ascorbate by high-performance thin layer chromatography and MALDI-TOF mass spectrometry. It has been shown that phosphatidic acid (PA) and phosphatidylhydroxyacetone (PHA) were formed in the system under conditions where hydrogen peroxide favours a release of heme iron from cyt c. The formation of PA and PHA occurs via an OH-induced fragmentation taking place in the polar moiety of cardiolipin. Formation of fragmentation products correlated with the loss of CL in CL/PC liposomes incubated with cyt c/H(2)O(2)/ascorbate or with Cu(2+)/H(2)O(2)/ascorbate.

The homeostasis of phosphatidylcholine and lysophosphatidylcholine was not disrupted during tri-o-cresyl phosphate-induced delayed neurotoxicity in hens

Little is known regarding early biochemical events in organophosphate-induced delayed neurotoxicity (OPIDN) except for the essential inhibition of neuropathy target esterase (NTE). We hypothesized that the homeostasis of lysophosphatidylcholine (LPC) and/or phosphatidylcholine (PC) in nervous tissues might be disrupted after exposure to the organophosphates (OP) which participates in the progression of OPIDN because new clues to possible mechanisms of OPIDN have recently been discovered that NTE acts as lysophospholipase (LysoPLA) in mice and phospholipase B (PLB) in cultured mammalian cells. To bioassay for such phospholipids, we induced OPIDN in hens using tri-o-cresyl phosphate (TOCP) as an inducer with phenylmethylsulfonyl fluoride (PMSF) as a negative control; and the effects on the activities of NTE, LysoPLA and PLB, the levels of PC, LPC, and glycerophosphocholine (GPC), and the aging of NTE enzyme in the brain, spinal cord, and sciatic nerves were examined. The results demonstrated that the activities of NTE, NTE-LysoPLA, LysoPLA, NTE-PLB and PLB were significantly inhibited in both TOCP- and PMSF-treated hens. The inhibition of NTE and NTE-LysoPLA or NTE-PLB showed a high correlation coefficient in the nervous tissues. Moreover, the NTE inhibited by TOCP was of the aged type, while nearly all of the NTE inhibited by PMSF was of the unaged type. No significant change in PC or LPC levels was observed, while the GPC level was significantly decreased. However, there is no relationship found between the GPC level and the delayed symptoms or aging of NTE. All results suggested that LPC and/or PC homeostasis disruption may not be a mechanism for OPIDN because the PC and LPC homeostasis was not disrupted after exposure to the neuropathic OP, although NTE, LysoPLA, and PLB were significantly inhibited and the GPC level was remarkably decreased.

Partitioning of propranolol in the phospholipid bilayer coat of anionic magnetoliposomes

This work deals with the partitioning of the cationic amphiphilic drug, propranolol, in the coating of so-called magnetoliposomes (MLs), which consist of nanometre-sized, magnetizable iron oxide cores covered with a phospholipid bilayer. MLs of two types were used: either the ML coat consisted entirely of anionic dimyristoylphosphatidylglycerol, or it was mixed with zwitterionic dimyristoylphosphatidylcholine in a 5/95 molar ratio. To separate sorbed from non-sorbed propranolol, high-gradient magnetophoresis was used. The sorption profiles clearly show that electrostatic interactions play a key role in the sorption process as drug incorporation in the ML coat was favoured by increasing the anionic character of the ML envelope and by reducing the salt concentration of the medium. Also, upon drug binding some phospholipid molecules were expelled from the ML coat. The observations may be of relevance in the biomedical field, i.e. in the development of ML-based, intracellular theranostics.

Specific heating power of fatty acid and phospholipid stabilized magnetic fluids in an alternating magnetic field

Magnetic fluids (MFs) with a similar narrow size distribution of the iron oxide core were stabilized with lauric acid (MF 1), oleate (MF 2) or, after dialysis in the presence of liposomes, with phospholipid molecules (MF 3 and MF 4, respectively). The hydrodynamic sizes of the MF 1 and MF 3 were half those found for MF 2 and MF 4. The MFs were exposed to inductive heating in an alternating magnetic field at a frequency of 200 kHz and a maximum magnetic field strength of 3.8 kA m(-1). Specific absorption rates (SAR) of 294 ± 42 (MF 1), 214 ± 16 (MF 2), 297 ± 13 (MF 3) and 213  ± 6 W g(-1) Fe (MF 4) were obtained. The data for MF 2 and MF 4 were identical to those found for the commercially available ferucarbotran. The biomedical relevance of the phospholipid-coated MFs is briefly discussed.

Anionic phospholipid-induced regulation of reactive oxygen species production by human cytochrome P450 2E1

We suggest that the cytochrome P450 2E1 (CYP2E1)-induced formation of reactive oxygen species (ROS) can be regulated by anionic phospholipids and the presence of the N-terminal region of the enzyme. When the content of cardiolipin (CL) in membranes at the expense of phosphatidylcholine matrix was increased, the ROS produced by recombinant human CYP2E1 was decreased as a function of CL concentration. On the contrary, the N-terminally truncated CYP2E1 had a decreased effect on the lipid-induced reduction of ROS formation. These results suggest that specific phospholipids can regulate the function of CYP2E1 by interaction with the enzyme including the N-terminal region(s).

Cellular responses of microcolonial rock fungi to long-term desiccation and subsequent rehydration

Melanised rock-inhabiting fungi are astonishingly resistant to environmental stresses. Also known as micro-colonial fungi (MCF), they are ubiquitous and even colonise bare rocks in deserts. To survive in nutrient poor and extremely stressful conditions, MCF have reduced morphogenetic complexity to a minimum, and rely on a broad spectrum of stress protection mechanisms. Although visual signs of carotenoid presence are masked by heavily melanised black cell-walls, we were able to isolate and characterise a variety of carotenoids (ss-carotene, zeta-carotene, phytoene, torularhodin and torulene) in the rock-inhabiting, relatively fast-growing strain A95. The desiccation/rehydration stress response was used to measure the ability of A95 to adapt to slow or fast changes in external conditions. Revival of MCF after prolonged desiccation and rehydration was documented by biochemical (analyses of lipids and protective pigments), cultivation, and microscopic methods. Survival of MCF is enhanced when desiccation is rapid and mycostasis is instant rather than following prolonged periods of low metabolic activity.

Lateral segregation of anionic phospholipids in model membranes induced by cytochrome P450 2B1: bi-directional coupling between CYP2B1 and anionic phospholipid

The lateral segregation of anionic phospholipids phosphatidic acid (PA), phosphatidylinositol (PI), and phosphatidylserine (PS) was detected after addition of cytochrome P450 2B1 (CYP2B1). The tendency of lipid clustering was highly dependent on the type of anionic phospholipids examined. PA was the most highly clustered while PI and PS clustered to a lesser degree. Moreover, liposomes containing anionic phospholipids form anionic phospholipid-rich microdomains in the presence of CYP2B1. Anionic phospholipids (mostly notably PA) also increased the ability of CYP2B1 to bind to lipid monolayers. In addition to the ability of CYP2B1 to modulate the physical properties of the membrane, the membrane itself can have reciprocal effects on the activity and conformation of CYP2B1. The catalytic activity of CYP2B1 increased as a function of anionic phospholipid concentration and in the presence of 10 mol% PA, the activity increased by 85%. These results suggest a bi-directional coupling between the CYP2B1 and anionic phospholipids.

Surface functionalization of magnetoliposomes in view of improving iron oxide-based magnetic resonance imaging contrast agents: Anchoring of gadolinium ions to a lipophilic chelate

Small unilamellar phospholipid vesicles containing the phosphatidylethanolamine-diethylene triamine pentaacetic acid (PE-DTPA) conjugate as one of the building stones were constructed. The ability of these colloids to complex gadolinium(III) ions at the surface of both the inner and outer bilayer shells was verified using a colorimetric method with Arsenazo III as a dye indicator. On incubation of these functionalized vesicles with magnetoliposomes (MLs, nanometer-sized magnetite cores encapsulated in a phospholipid bilayer), PE-DTPA percolates into the ML coat. The PE-DTPA content could be fine-tuned by varying the conjugate concentration in the donor vesicles. In the experimental conditions applied, up to 500 Gd(3+) ions were immobilized per ML colloid. The resulting ML-Gd(3+) complexes might have great potential, for example, as a novel magnetic resonance imaging contrast agent.

Glaciecola agarilytica sp. nov., an agar-digesting marine bacterium from the East Sea, Korea

A taxonomic study was carried out on an isolate, strain NO2T, from marine sediment collected from the East Sea, Korea. Comparative 16S rRNA gene sequence studies showed that this strain belonged to the Gammaproteobacteria and was most closely related to Glaciecola mesophila KMM 241T and Glaciecola polaris LMG 21857T (98.6 and 98.0 % 16S rRNA gene sequence similarity, respectively). The isolate was Gram-negative, aerobic and slightly halophilic and grew in 2–8 % NaCl and at 7–30 °C. Strain NO2T shared some physiological and biochemical properties with G. mesophila KMM 241T and G. polaris LMG 21857T. The G+C content of the genomic DNA of strain NO2T was 45 mol%. Strain NO2T possessed C16 : 0, summed feature 4 (C16 : 1 ω7c and/or iso-C15 : 0 2-OH) and summed feature 7 (C18 : 1 ω9c/ω12t/ω7c) as the major cellular fatty acids. DNA–DNA relatedness data indicated that strain NO2T represents a distinct species that is separate from G. mesophila and G. polaris. On the basis of polyphasic evidence, it is proposed that strain NO2T (=KCTC 12755T=LMG 23762T) represents the type strain of a novel species, Glaciecola agarilytica sp. nov.

Dietaryn-3 andn-6 fatty acids alter avian metabolism: molecular-species composition of breast-muscle phospholipids

The effects of diets high inn-3 polyunsaturated fatty acids (PUFA; provided by fish oil),n-6 PUFA (sunflower oil) or in more-saturated fatty acids (tallow) on the distribution of subclasses of choline phospholipids (PC) and ethanolamine phospholipids (PE) from the breast muscle of broiler chickens were examined. Supplementation with the different fatty acids had no effect on the distribution of phospholipid subclasses. Feeding sunflower oil or tallow gave a molecular-species profile similar in both fatty acid subtype and proportion. In the diacyl PC phospholipids, 16: 0–18: 1n-9 and 16: 0–18: 2n-6 accounted for approximately 60 % of the total molecular species, whereas for the alkylenyl PC the predominant species were 16: 0–18: 1n-9 and 16: 0–20: 4n-6. Of the diacyl PE the dominant species was 18: 0–20: 4n-6 which accounted for 50 % of the molecular species, and of the alkylenyl PE the dominant species were 16: 0–18: 1n-9, 16: 0–20: 4n-6 and 18: 0–20: 4n-6. Supplementation with fish oil significantly increased levels of both eicosapentaenoic acid (20: 5n-3) and docosahexaenoic acid (22: 6n-3) in PC and PE when compared with either sunflower oil or tallow supplementation. The increase in then-3 PUFA incorporation was associated with a corresponding decrease in the proportion of arachidonic acid (20: 4n-6) in both PC and PE. Different dietary fats induce different patterns of fatty acid incorporation and substitution in thesn-2 position of the diacyl and alkylenyl PC and PE of avian breast muscle, and this finding is indicative of selective acyl remodelling in these two phospholipids.

Evaluation of the interaction of propranolol with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) liposomes: the partitioning model

The sorption behavior of the amine containing beta-receptor blocking agent propranolol (Ppn) in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) vesicles was investigated. Both protonated and unprotonated Ppn were measured in the continuous phase after removal of the vesicles containing sorbed Ppn by centrifugation. In contrast, by analyzing the surface charge density, deduced from electrophoretic mobility measurements, only the sorbed protonated Ppn was determined. A partitioning model was used to describe the sorption behavior. Sensitivity analysis revealed that sufficiently reliable and independent parameters were obtained. The partition coefficient of the unprotonated Ppn was about 22 times higher than that of the protonated analogue. Statistical analysis revealed a significant increase in the intrinsic partition coefficients of both Ppn analogues with an increase in the salt concentration.

Polysaccharide and lipid composition of the brown seaweed Laminaria gurjanovae

Polysaccharide and lipid composition of the Pacific brown seaweed Laminaria gurjanovae is determined. Alginic acid is shown to be the main polysaccharide of its biomass (about 28%); it consists of mannuronic and guluronic acid residues at a ratio of 3 : 1. The yield of water-soluble polymannuronic acid is low and does not exceed 1.1% of dry biomass. High laminaran content (about 22%) is found, whereas the yield of fucoidan is no more than 3.6%. Laminaran consists of two fractions, soluble and insoluble in cold water, their ratio is 2.5 : 1. Practically, insoluble laminaran is a linear 1,3-beta-D-glucan, and the soluble fraction was shown to be 1,3;1,6- 3-D-glucan. The oligosaccharide products of desulfation or partial acidic hydrolysis of fucoidan were studied by MALDI TOF MS; they were found to be fuco- and galactooligosaccharides. The fucoidan is suggested to be a highly sulfated partially acetylated galactofucan (Fuc/Gal is -1 : 1). The main lipid components of the dried L. gurjanovae are neutral lipids and glyceroglycolipids, whereas phospholipids are found in minor amounts. The main fatty acid components of lipids are 14 : 0, 16 : 0, 16 : 1 n-7, 18 : 1 n-7, and 18 : 2 n-6 acids.

Red/far-red light modulates phospholipase D activity in oat seedlings: relation of enzyme photosensitivity to photosynthesis

Phospholipase D (PLD) activity was found to be higher in etiolated oat seedlings than in green seedlings. White and red (R) light exposure inhibited PLD activity in etiolated seedlings. Far-red light eliminated R-light-induced decrease in PLD activity, indicating phytochrome participation in observed photomodulation. Inhibitor of electron transport in chloroplast 3-(3,4-dichlorophenyl)-1,1-dimethylurea stimulated and glucose suppressed PLD activity in green and etiolated oat seedlings, respectively. These results suggest that PLD activity in oat seedling is regulated by light with involvement of phytochrome photoreceptor, and associated with photosynthesis process.

Effect of hydrogen peroxide on ejection of cell nucleus from pigeon erythrocytes and state of membrane lipids

The nuclei are ejected from the pigeon erythrocytes and apoptotic vesicles form in these cells in the presence of hydrogen peroxide. Hydrogen peroxide intensifies LPO processes and changes phospholipid content. The relative content of phosphatidylcholine, sphingomyelin, and phosphatidylserine decreased, while that of phosphatidylethanolamine and lisophosphatidylcholine increased. The content of unsaturated fatty acids also decreased under these conditions. Presumably, these changes in the lipid phase of the erythrocyte membrane are a mechanism preparing the cell to nucleus ejection and apoptosis.

Mesonia mobilis sp. nov., isolated from seawater, and emended description of the genus Mesonia

The taxonomic position of a novel marine, heterotrophic, strictly aerobic, gliding and yellow-pigmented bacterium, designated strain KMM 6059T, was determined. 16S rRNA gene sequence analysis revealed that this strain represents a member of the genus Mesonia. Phenotypic and chemotaxonomic data showed that the isolate represents a novel species of the genus Mesonia, for which the name Mesonia mobilis sp. nov. is proposed. The type strain is KMM 6059T (=KCTC 12708T=LMG 23670T). An emended description of the genus Mesonia based on the new data is also given.

Lipid class and fatty acid composition of the boreal soft coral Gersemia rubiformis

Total lipid, phospholipid, and FA composition and distribution of FA between polar lipids (PL) and neutral lipids (NL) were investigated in the boreal soft coral Gersemia rubiformis from the Bering Sea. The total lipids were mostly hydrocarbons and waxes (33.7%) and PL (33.1%). The content of monoalkyldiacylglycerols (9.7%) exceeded the content of TAG (6.7%). PC and PE constituted 31.4% and 25.6% of total phospholipids, respectively. Principal FA were 16:0, 16:1n-7, 18:0, 18:1n-9, 18:1n-7, 20:1n-7, 20:4n-6, 20:4n-3, 20:5n-3, 22:5n-3, 22:6n-3, 24:5n-6, and 24:6n-3. Most n-6 PUFA (52% of total FA) were associated with the PL fraction; this was especially true for arachidonic and tetracosapentaenoic acids. The NL were enriched with mono-, di-, trienoic, and n-3 PUFA. The variation in EPA levels in both NL and PL suggests an origin of this acid from lipids of diatoms consumed by the corals.

Effects of signal peptide and adenylate on the oligomerization and membrane binding of soluble SecA

SecA protein, a cytoplasmic ATPase, plays a central role in the secretion of signal peptide-containing proteins. Here, we examined effects of signal peptide and ATP on the oligomerization, conformational change, and membrane binding of SecA. The wild-type (WT) signal peptide from the ribose-binding protein inhibited ATP binding to soluble SecA and stimulated release of ATP already bound to the protein. The signal peptide enhanced the oligomerization of soluble SecA, while ATP induced dissociation of SecA oligomer. Analysis of SecA unfolding with urea or heat revealed that the WT signal peptide induces an open conformation of soluble SecA, while ATP increased the compactness of SecA. We further obtained evidences that the signal peptide-induced oligomerization and the formation of open structure enhance the membrane binding of SecA, whereas ATP inhibits the interaction of soluble SecA with membranes. On the other hand, the complex of membrane-bound SecA and signal peptide was shown to resume nucleotide-binding activity. From these results, we propose that the translocation components affect the degree of oligomerization of soluble SecA, thereby modulating the membrane binding of SecA in early translocation pathway. A possible sequential interaction of SecA with signal peptide, ATP, and cytoplasmic membrane is discussed.

Zobellella denitrificans gen. nov., sp. nov. and Zobellella taiwanensis sp. nov., denitrifying bacteria capable of fermentative metabolism

Two denitrifying strains of heterotrophic, facultatively anaerobic bacteria, designated ZD1T and ZT1T, were isolated from sediment samples collected from mangrove ecosystems in Taiwan. The isolates were Gram-negative. Cells grown in broth cultures were straight rods that were motile by means of a single polar flagellum. The isolates grew optimally in 1–3 % NaCl, but NaCl was not an absolute requirement for growth; only strain ZT1T grew in 13–14 % NaCl. Both isolates grew between 10 and 45 °C, with optimum growth at 30–35 °C. They were capable of anaerobic growth by denitrifying metabolism using nitrate or nitrous oxide as terminal electron acceptors or, alternatively, by fermenting glucose, sucrose or mannitol as substrates. C18 : 1 ω7c was the most abundant fatty acid (32.6–35.7 %). The other major fatty acids included C16 : 1 ω7c (27.5–29.4 %) and C16 : 0 (20.1–22.0 %). The two isolates had 16S rRNA gene sequence similarity of 96.8 % and shared 94.1–96.8 % sequence similarity with the most closely related species, Oceanimonas doudoroffii, Oceanimonas baumannii, Oceanimonas smirnovii and Oceanisphaera litoralis. They could be distinguished from these species in that they were capable of fermentative metabolism, had relatively high DNA G+C contents (62.0–64.0 mol%) and contained C18 : 1 ω7c instead of C16 : 1 ω7c as the most abundant fatty acid. Characterization data accumulated in this study revealed that the two denitrifying isolates could be classified as representatives of two novel species in a new genus, Zobellella gen. nov., with Zobellella denitrificans sp. nov. (type strain ZD1T=BCRC 17493T=JCM 13380T) as the type species and Zobellella taiwanensis sp. nov. (type strain ZT1T=BCRC 17494T=JCM 13381T) as a second species.

Design and synthesis of novel antimicrobial peptides on the basis of alpha helical domain of Tenecin 1, an insect defensin protein, and structure-activity relationship study

Tenecin 1, a peptide consisting of 43 amino acids, exhibits a potent bactericidal activity against various Gram-positive bacteria and shares a common structural feature of insect defensin family corresponding to cysteine stabilized alpha/beta motif. Our previous research indicated that an active fragment was successfully extracted from C-terminal beta sheet domain of Tenecin 1, whereas the fragment corresponding to the alpha helical region of the protein had no antibacterial activity. We chose this inactive fragment corresponding to alpha helical region of Tenecin 1 and synthesized derivatives with a different net positive charge by using rational design. Interestingly, we successfully endowed antibacterial activity as well as antifungal activity to the inactive alpha helical fragment by single or double amino acid replacement(s) without an increase of hemolytic activity. The leakage of dye from vesicles induced by the active peptides suggested that these peptides act on the membranes of pathogen as a primary mode of action. Structure-activity relationship study of a series of the active derivatives revealed that amphiphilic structure and high net positive charge were prerequisite factors for the activity and that there was a relationship between the antibacterial activity and the isoelectric point of the active peptides. In this work, we showed an efficient method to endow the antibacterial activity as well as antifungal activity to the inactive fragment derived from a cyclic insect defensin protein and suggested a facile method to screen for active fragments from cyclic host defense peptides.

Oceanisphaera donghaensis sp. nov., a halophilic bacterium from the East Sea, Korea

A taxonomic study was carried out on two isolates, strains BL1Tand BL11, from marine sediment collected from the East Sea, Korea. Comparative 16S rRNA gene sequence studies showed that these isolates clearly affiliated with theGammaproteobacteria. BL1Tand BL11 were most closely related toOceanisphaera litoralisKMM 3654T(97·6 and 97·7 % 16S rRNA gene sequence similarity, respectively). The level of 16S rRNA gene sequence similarity between strains BL1Tand BL11 was 99·7 %. The two isolates were Gram-negative, aerobic, moderately halophilic, and grew in 0·5–8·0 % NaCl and at 4–42 °C. Strains BL1Tand BL11 shared some physiological and biochemical properties withO. litoralisKMM 3654T, although they differed in that BL1Tand BL11 were able to utilize ethanol, proline and alanine. The G+C contents of the genomic DNA of strains BL1Tand BL11 were 56·6 and 57·1 mol%, respectively. Both strains possessed C16 : 1ω7cand/or iso-C15 : 02-OH, C16 : 0and C18 : 1ω7cas the major fatty acids. DNA–DNA relatedness data indicated that strains BL1Tand BL11 represent a genomic species that is separate fromO. litoralisKMM 3654T. On the basis of polyphasic evidence, it is proposed that strain BL1T(=KCTC 12522T=DSM 17589T) represents the type strain of a novel species,Oceanisphaera donghaensissp. nov.

De novo biosynthesis of dihydrosphingosine-1-phosphate by sphingosine kinase 1 in mammalian cells

Sphingosine kinase 1 (SK1) is one of the two known kinases, which generates sphingosine-1-phosphate (S1P), a potent endogenous lipid mediator involved in cell survival, proliferation, and cell-cell interactions. Activation of SK1 and intracellular generation of S1P were suggested to be part of the growth and survival factor-induced signaling, and overexpression of SK1 provoked cell tumorigenic transformation. Using a highly selective and sensitive LC-MS/MS approach, here we show that SK1 overexpression, but not SK2, in different primary cells and cultured cell lines results in predominant upregulation of the synthesis of dihydrosphingosine-1-phosphate (DHS1P) compared to S1P. Stable isotope pulse-labeling experiments in conjunction with LC-MS/MS quantitation of different sphingolipids demonstrated strong interference of overexpressed SK1 with the de novo sphingolipid biosynthesis by deviating metabolic flow of newly formed sphingoid bases from ceramide formation toward the synthesis of DHS1P. On the contrary, S1P biosynthesis was not directly linked to the de novo sphingoid bases transformations and was dependent on catabolic generation of sphingosine from complex sphingolipids. As a result of SK1 overexpression, migration and Ca2+-response of human pulmonary artery endothelial cells (HPAEC) to stimulation with external S1P, but not thrombin, was strongly impaired. In contrast, selective increase in intracellular content of DHS1P or S1P through the uptake and phosphorylation of corresponding sphingoid bases had no effect on S1P-induced signaling or facilitation of wound healing. Furthermore, infection of human bronchial epithelial cells (HBEpC) with RSV A-2 virus increased SK1-mediated synthesis of DHS1P and S1P, whereas TNF-alpha enhanced only S1P production in HPAEC. These findings uncover a new functional role for SK1, which can control survival/death (DHS1P-S1P/ceramides) balance by targeting sphingolipid de novo biosynthesis and selectively generating DHS1P at a metabolic step preceding ceramide formation.

Expression of the cationic antimicrobial peptide lactoferricin fused with the anionic peptide in Escherichia coli

Direct expression of lactoferricin, an antimicrobial peptide, is lethal to Escherichia coli. For the efficient production of lactoferricin in E. coli, we developed an expression system in which the gene for the lysine- and arginine-rich cationic lactoferricin was fused to an anionic peptide gene to neutralize the basic property of lactoferricin, and successfully overexpressed the concatemeric fusion gene in E. coli. The lactoferricin gene was linked to a modified magainin intervening sequence gene by a recombinational polymerase chain reaction, thus producing an acidic peptide-lactoferricin fusion gene. The monomeric acidic peptide-lactoferricin fusion gene was multimerized and expressed in E. coli BL21(DE3) upon induction with isopropyl-beta-D-thiogalactopyranoside. The expression levels of the fusion peptide reached the maximum at the tetramer, while further increases in the copy number of the fusion gene substantially reduced the peptide expression level. The fusion peptides were isolated and cleaved to generate the separate lactoferricin and acidic peptide. About 60 mg of pure recombinant lactoferricin was obtained from 1 L of E. coli culture. The purified recombinant lactoferricin was found to have a molecular weight similar to that of chemically synthesized lactoferricin. The recombinant lactoferricin showed antimicrobial activity and disrupted bacterial membrane permeability, as the native lactoferricin peptide does.

New insights into self-organization of a model lipid mixture and quantification of its adsorption on spherical polymer particles

The adsorption of lipids onto spherical polymer colloids led to original assemblies presenting structural characteristics adjustable with the lipid formulation. The model system selected for this work involved sulfate-charged poly(styrene) submicrometer particles and zwitterionic/cationic lipid mixtures composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dipalmitoyl-3-trimethylammonium-propane (DPTAP). According to the theoretical packing parameter calculations and whatever the DPPC/DPTAP ratio, the two lipids self-assembled in aqueous media to spontaneously form vesicles. A phase transition investigation of these DPPC/DPTAP vesicles using differential scanning calorimetry revealed particular thermotropic behaviors, especially for the equimolar formulation where very strong interactions occurred between DPPC and DPTAP. Furthermore, the coating of the lipids around particles was monitored versus DPPC/DPTAP ratio by means of numerous appropriate techniques. First, a thermogravimetric analysis, providing decomposition profiles of lipid/polymer particle assemblies with temperature, was atypically carried out for such nanostructures. Then, 1H NMR spectroscopy enabled the exact DPPC/DPTAP molar ratios adsorbed on particles to be determined by differentiating both lipids. Subsequently, it also pointed out the major role of electrostatic interactions as driving forces in the assembly elaboration process. In addition to these findings, quantitative information has been collected and correlated with chemical lipid assays and permitted the statement of a lipid bilayer coverage for the assemblies prepared in water, in agreement with quasi-elastic light scattering data.