Distribution Of Molecular Species Research Articles

Direct observation of de-mixing in a ceramic metal-halide arc lamp

De-mixing of additives in a vertically-operated, ceramic DyI3–CsI–Hg metal-halide arc lamp has been observed by examining the ratios of absolute elemental densities as a function of position. As the elemental densities have been obtained directly by x-ray induced fluorescence (Curry J J, Adler H G, Shastri S D and Lee W-K 2003 J. Appl. Phys. 93 2359), this approach reveals the extent of mixing (or de-mixing) with no intervening assumptions about equilibrium, the local temperature, or the accuracy of partition functions. The metal additives in the arc studied show complex de-mixing. Depletion of Dy and Cs from the core is attributed to ambipolar cataphoresis. These same additives also exhibit a relative enhancement in a layer just outside the core before decreasing again toward the wall. Thermochemical data are used to derive radial distributions of molecular species given the experimentally obtained elemental densities and the gas temperature assuming a lamp operating pressure of 106 Pa (10 atm).

Sphingomyelin composition and physical asymmetries in native acetylcholine receptor-rich membranes.

Selective enzymatic hydrolysis, lipid compositional analyses, and fluorescence studies have been carried out on acetylcholine receptor (AChR)-rich membranes from Torpedinidae to investigate the topology of sphingomyelin (SM) in the native membrane and its relationship with the AChR protein. Controlled sphingomyelinase hydrolysis of native membranes showed that SM is predominantly (approximately 60%) localized in the outer half of the lipid bilayer. Differences were also observed in the distribution of SM fatty acid molecular species in the two bilayer leaflets. A fluorescent SM derivative ( N-[10-(1-pyrenyl)decanoyl]sphingomyelin; Py-SM) was used to study protein-lipid interactions in the AChR-rich membrane and in affinity-purified Torpedo AChR reconstituted in liposomes made from Torpedo electrocyte lipid extracts. The efficiency of Förster resonance energy transfer (FRET) from the protein to the pyrenyl-labeled lipid as a function of acceptor surface density was used to estimate distances and topography of the SM derivative relative to the protein. The dynamics of the lipid acyl chains were explored by measuring the thermal dependence of Py-SM excimer formation, sensitive to the fluidity of the membrane. Differences were observed in the concentration dependence of excimer/monomer pyrenyl fluorescence when measured by direct excitation of the probe as against under FRET conditions, indicating differences in the intermolecular collisional frequency of the fluorophores between bulk and protein-vicinal lipid environments, respectively. Py-SM exhibited a moderate selectivity for the protein-vicinal lipid domain, with a calculated relative affinity K(r) approximately 0.55. Upon sphingomyelinase digestion of the membrane, FRET efficiency increased by about 50%, indicating that the resulting pyrenyl-ceramide species have higher affinity for the protein than the parental SM derivative.

Analysis of phospholipid molecular species distributions by fast atom bombardment mass spectrometry (FAB-MS)

Analysis of phospholipid molecular species distributions by fast atom bombardment mass spectrometry (FAB-MS)

Analysis of phospholipid molecular species distributions by fast atom bombardment mass spectrometry (FAB-MS)

Les methodes traditionnelles d'ionisation lors de la spectrometrie de masse ne sont pas appropriees aux phospholipides qui manquent de volatilite et souffrent d'une fragmentation extensive. Ces problemes sont surpasses par un bombardement d'atomes avec du gaz inerte qui produit des ions moleculaires avec une fragmentation relativement reduite. Ainsi, les melanges peuvent etre analyses ce qui est important dans le cas de phospholipides naturels. Avant son introduction dans le spectrometre, l'echantillon a analyser est melange avec un fluide matrice approprie. A cause de l'activite de surface, les molecules de phospholipides peuvent etre ionisees a partir de la surface de la matrice. Cette methode, plutot adaptee a l'analyse des phospholipides, est traitee dans cet article ainsi que l'analyse des spectres et les techniques additionnelles et specialisees.

Molecular species composition of rat liver phospholipids by ESI-MS/MS: the effect of chromatography

Using electrospray ionization tandem mass spectrometry (ESI-MS/MS) this study shows that the loss of glycerophospholipid (GPL) after chromatography was unevenly distributed across the GPL molecular species. Both TLC and HPLC caused a preferential loss of GPL with 0 to 3 double bonds: 20% and 7.2% for choline glycerophosphates (PC) and 19.7% and 7.5% for ethanolamine glycerophosphates (PE), respectively. A consequence of these losses was that GPLs containing fatty acids with four or more double bonds had a greater contribution to the total after chromatography. ESI-MS/MS analysis also showed that PC molecular species with four or more double bonds migrated at the front of the TLC band of PCs. GPLs extracted from TLC plates occasionally contained PCs that were smaller than those in the original extract. These low molecular mass PCs were easily reduced to alcohols and formed derivatives with 2,4-dinitrophenylhydrazine, suggesting that aldehydes were generated by the oxidation of unsaturated fatty acids. Directly analyzing lipid extracts by ESI-MS/MS without preliminary chromatographic separation gives an accurate distribution of GPL molecular species in lipid mixtures. However, the ionization of the phospholipids in the electrospray jet maximized at relatively low concentrations of GPL. There was a linear response between phospholipid mass and ion intensity for concentrations around 1-2 nmol/ml for both PC and PE. The total ion intensity continued to increase with concentrations above 1-2 nmol/ml, but the response was non-linear.

Structural modification of single-axis-oriented yttria-stabilized-zirconia films under zirconium ion bombardment

Crystal size and orientation control of yttria-stabilized-zirconia (YSZ) films produced by pulsed-laser deposition under zirconium-ion bombardment are reported. A structure development mechanism is proposed based on the correlation between ablated plasma chemistry, velocity distributions of atomic and molecular species in the plasma, bombardment energy, time, incidence angle, film crystal size, and orientation. A near-room-temperature growth of single-axis-oriented YSZ films with (002) texture on randomly oriented polycrystalline substrates is demonstrated.

Phospholipid composition in late infantile neuronal ceroid lipofuscinosis.

Neuronal ceroid lipofuscinosis (NCL) is a relatively common group of inherited neurodegenerative disorders characterised by the accumulation of autofluorescent lipopigments (ceroid) similar to lipofuscin. Because of this property, studies have concentrated on fatty acid metabolism and lipid peroxidation. In the present study, the fatty acid composition of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) and the molecular species compositions of diacylglycerophosphocholine (diacyl GPC), diacylglycerophosphoethanolamine (diacyl GPE) and alkenylacyl GPE (plasmalogens) were investigated in cultured skin fibroblasts from three patients with a confirmed diagnosis of the late infantile form of the disease (LINCL, CLN2) and three healthy age-matched controls. Relatively minor differences in the fatty acid compositions of PC and PE were observed between patients and controls. However, dimethyl acetals of plasmalogens were found to be 40% higher in the patients compared to in the controls. Control and LINCL fibroblasts displayed only slight differences in the molecular compositions of diacyl GPE and diacyl GPC. In contrast, compared with normal cells, LINCL fibroblasts had higher levels of alkenylacyl GPE species containing both 18 : 1 and polyunsaturated fatty acids, but lower levels of species with 16 : 0 or 18 : 0 in the sn-1 position. The molecular composition of PC and PE subclasses in skin fibroblasts of healthy subjects and patients suffering from LINCL is here described for the first time. While few differences are noticeable in the fatty acid composition of PC and PE and the molecular species distribution of diacylGPC and diacylGPE, the alkenylacyl GPE (or ethanolamine plasmalogens) were found to differ significantly between patients and healthy controls.

99mTc-labeled chemotactic peptides: influence of coligand on distribution of molecular species and infection imaging properties. Synthesis and structural characterization of model complexes with the {Re(η 2-HNNC 5H 4N)(η 1-NNC 5H 4N)} core

99mTc-labeled hydrazino nicotinamide (HYNIC) derivatized chemotactic peptides are useful infection imaging agents. However, the reagent that is used for radiolabeling (‘coligand’) can have profound effects on biodistribution. In this study, the distribution of molecular species formed with a variety of coligands was correlated with infection localization and biodistribution in E. coli infected rabbits. Five 99mTc-coligand complexes (mannitol, glucamine, glucarate, tricine and glucoheptonate) were used to label f-MLFK-HYNIC and radiolabeled species were characterized by reverse phase HPLC. One mCi of each 99mTc-coligand–peptide complex was injected into rabbits 24 h after infection and imaging was performed 3–4 and 16–17 h later. After acquiring the final images, the animals were euthanized and biodistribution was measured. With all five coligands, 99mTc-labeled peptide was obtained in >90% radiochemical purity. Multiple radiolabeled species were obtained with each reagent; however, mannitol yielded the most homogeneous product. Model studies on the robust {Re(η 2-HNNC 5H 4N)(η 1-NNC 5H 4)} core demonstrate that ligands such as mannitol, tricine, tris(hydroxymethyl)propane, glucarate-a, glucarate-b, and glucoheptonate yield intractable mixtures of products as a consequence of the ambidentate nature of these ligands and their facile displacement by other donor groups, including solvent molecules. In contrast, dihydroxylic ligands with an additional imine functionality and a meridional geometric preference yield monophasic materials upon reaction with [ReCl 3(η 1-NNC 5H 4NH)(η 2-HNNC 5H 4N)]. Both [Re{η 3-C 5H 3N-2,6-(CH 2O) 2}(η 1-NNC 5H 4N)(η 2-HNNC 5H 4N)] ( 1) and [Re{η 3-OC 6H 4C(H)NC 6H 4O}(η 1-NNC 5H 4N)(η 2-HNNC 5H 4N)] ( 2) exhibit distorted octahedral geometries with a meridional disposition of the bidentate pyridinediazene and pyridinediazenido(1−) ligands and the three remaining meridional positions occupied by the two oxygen and the nitrogen donors of the tridentate coligand. Image analysis demonstrated that 99mTc-mannitol-f-MLFK-HYNIC produced the highest target to background ratios (T/B). The T/B values were: 3.91±0.99, 6.15±1.07, 2.8±1.07, 2.57±1.07, 3.41±1.07 and 1.8±1.07 at 3–4 h and 11.9±0.99, 3.94±1.07, 3.79±1.07, 4.81±1.17, 7.0±1.31 and 5.32±1.07 at 16–17 h for mannitol, tricine, glucamine, glucarate-a, glucarate-b, and glucoheptonate, respectively. At both imaging times, 99mTc-mannitol-f-MLFK-HYNIC had the lowest relative levels of accumulation in bowel. Biodistribution measurements demonstrated that the mannitol preparation had the highest level of accumulation (%ID g −1) in infected tissue; mannitol>glucoheptonate=glucarate-b>glucarate-a>glucamine>tricine; P<0.01. The infected to normal muscle ratio for 99mTc-mannitol-f-MLFK-HYNIC was ∼50:1. These results support our previous findings in rats that coligands can markedly effect the biodistribution and infection localization of 99mTc-labeled HYNIC chemotactic peptides. For infection imaging, the mannitol preparation had the most favorable combination of accumulation in infected tissue, T/B ratio and biodistribution in uninfected organs.

Effect of soybean oil and fish oil on individual molecular species of Atlantic salmon head kidney phospholipids determined by normal-phase liquid chromatography coupled to negative ion electrospray tandem mass spectrometry

The effect of soybean oil (SO) and fish oil (FO) on the relative molecular species distribution of phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and phosphatidylserine (PS) in Atlantic salmon head kidney was studied using normal-phase liquid chromatography coupled with negative ion electrospray tandem mass spectrometry. The conformation of identity of the phospholipid species was based on retention time, the mass of the [M−H] − ([M−15] − for PC) molecular ions and the carboxylate anion fragments in the product ion spectrum. The intensity ratio of sn-1/ sn-2 fragment ions increased with increasing number of double bonds in the sn-2 acyl chain but was not affected by increasing number of double bonds in the sn-1 acyl chain of the species examined. The relative distribution of the molecular species was determined by multiple reaction monitoring of the carboxylate anion fragment from the sn-1 position. A total of 68 different phospholipid species were determined in the head kidney and the largest amount was found in PE (22 species). Depending on the diet, the main species identified in the different phospholipid classes were; PC 16:0/18:1, PE 16:0/22:6, PI 18:0/20:4 and PS 16:0/22:6. The SO diet significantly increased the 18:2, 20:3 and most 20:4 containing species and significantly reduced the 14:0 and most 20:5 and 22:6 fatty acid containing species. The increase of the 20:4 and the decrease of the 20:5 and 22:6 containing species were dependent on the fatty acid combination of the species

The curvature and cholesterol content of phospholipid bilayers alter the transbilayer distribution of specific molecular species of phosphatidylethanolamine.

The curvature, cholesterol content, and transbilayer distribution of phospholipids significantly influence the functional properties of cellular membranes, yet little is known of how these parameters interact. In this study, the transbilayer distribution of phosphatidylethanolamine (PE) is determined in vesicles with large (98 nm) and small (19 nm) radii of curvature and with different proportions of PE, phosphatidylcholine, and cholesterol. It was found that the mean diameters of both types of vesicles were not influenced by their lipid composition, and that the amino-reactive compound 2,4,6-trinitrobenzenesulphonic acid (TNBS) was unable to cross the bilayer of either type of vesicle. When large vesicles were treated with TNBS, approximately 40% of the total membrane PE was derivatized; in the small vesicles 55% reacted. These values are interpreted as representing the percentage of total membrane PE residing in the outer leaflet of the vesicle bilayer. The large vesicles likely contained approximately 20% of the total membrane lipid as internal membranes. Therefore, in both types of vesicles, PE as a phospholipid class was randomly distributed between the inner and outer leaflets of the bilayer. The proportion of total PE residing in the outer leaflet was unaffected by changes in either the cholesterol or PE content of the vesicles. However, the transbilayer distributions of individual molecular species of PE were not random, and were significantly influenced by radius of curvature, membrane cholesterol content, or both. For example, palmitate- and docosahexaenoate-containing species of PE were preferentially located in the outer leaflet of the bilayer. Membrane cholesterol content affected the transbilayer distributions of stearate-, oleate-, and linoleate-containing species. The transbilayer distributions of palmitate-, docosahexaenoate-, and stearate-containing species were significantly influenced by membrane curvature, but only in the presence of high levels of cholesterol. Thus, differences in membrane curvature and cholesterol content alter the array of PE molecules present on the surfaces of phospholipid bilayers. In cells and organelles, these differences could have profound effects on a number of critical membrane functions and processes.

Low Molecular Weight Group IIA and Group V Phospholipase A2 Enzymes Have Different Intracellular Locations in Mouse Bone Marrow-derived Mast Cells

The subcellular location of the enzymes of eicosanoid biosynthesis is critical for their co-ordinate action in the generation of leukotrienes and prostaglandins. This activity is thought to occur predominantly at a perinuclear location. Whereas the subcellular locations of cytosolic phospholipase (PL) A(2) and each of the pathway enzymes of eicosanoid generation have been defined, the distribution of the low molecular weight species of PLA(2) has remained elusive because of the lack of antibodies that distinguish among homologous family members. We have prepared affinity-purified rabbit antipeptide IgG antibodies that distinguish mouse group IIA PLA(2) and group V PLA(2). Immunofluorescence staining and immunogold electron microscopy reveal different subcellular locations for the enzymes. Group IIA(2) PLA(2) is present in the secretory granules of mouse bone marrow-derived mast cells, consistent with its putative role in facilitating secretory granule exocytosis and its consequent extracellular action. In contrast, group V PLA(2) is associated with various membranous organelles including the Golgi apparatus, nuclear envelope, and plasma membrane. The perinuclear location of group V PLA(2) is consistent with a putative interaction with translocated cytosolic PLA(2) in supplying arachidonic acid for generation of eicosanoid products, while the location in Golgi cisternae may also reflect its action as a secreted enzyme. The spatial segregation of group IIA PLA(2) and group V PLA(2) implies that these enzymes are not functionally redundant.

Phospholipid molecular species distribution of some medically important Candida species analysed by fast atom bombardment mass spectroscopy.

The aim of this study was to obtain detailed information on phospholipids (PL) of the medically important Candida species and to determine their possible chemotaxonomic significance. Lipids were extracted from 22 strains representing 8 Candida species and their PL molecular species distributions were determined by Fast Atom Bombardment Mass Spectroscopy (FAB MS) in negative ion mode. Fifteen major lower mass peaks (m/z 221 to 289) were attributable to the expected presence of carboxylate anions and 24 major higher mass peaks (m/z 557 to 837) were attributable to phospholipid anions. Major carboxylate peaks were of the following m/z and identities : 253, C16:1; 255, C16:0; 277, C18:3; 279, C18:2; 281, C18:1; and 283, C18:0. The most abundant peaks consistent with the presence of phospholipid molecular species anions include those of m/z 673, 743, 833, 834 and 836 tentatively identified as phosphatidic acid (PA) (34:1), phosphatidylglycerol (PG) (34:3), phosphtidylinositol (PI) (34:2) and two unknown molecular species. This profile is diagnostic for the genus Candida. Quantitative differences were observed between different Candida species. Thus, polar lipid molecular species distribution in Candida spp. has chemotaxonomic significance, especially so in the case of carboxylate anions.

Elemental and molecular imaging of human hair using secondary ion mass spectrometry.

Secondary ion mass spectrometry (SIMS) is used to image the spatial distribution of elemental and molecular species on the surface and in cross sections of doped human hair using a magnetic sector SIMS instrument operated as an ion microprobe. Analysis of electrically insulating, non-planar hair samples requires one of two different methods of charge compensation to be used depending on the polarity of the sputtered secondary ions. For detection of positive secondary ions, the hair is imaged using a approximately 0.5 micron diameter, 19.5 keV impact energy, O- microbeam with no auxiliary electron bombardment. For detection of negative secondary ions, a approximately 0.2 micron diameter, 14.5 keV impact energy Cs+ microbeam is used in conjunction with normal incidence, low-energy electron bombardment. Both of these methods allow submicrometer spatial resolution elemental and molecular secondary ion images to be obtained from hair samples without metallic coating of the sample surface prior to analysis. Several examples are presented that reflect potential application areas for these analytical methods.

Effect of genetic modification on the distribution of minor constituents in canola oil

AbstractOil derived from different lines of genetically modified canola varieties was analyzed for phospholipids, tocopherols, and phytosterols by various chromatographic techniques. As observed previously in genetically modified soybean oils, there was a decrease in the content and composition of phosphatidic acid in three of the modified canola oils derived from the 12 varieties investigated. Normal‐phase high‐performance liquid chromatographic (HPLC) analyses showed small variations in the phospholipid content of major classes, despite few differences in their composition. Reversed‐phase HPLC data indicated that the molecular species distribution of phosphatidylethanolamine was significantly altered by genetic modification when compared to phosphatidylcholine. Impact of oilseed modification on the tocopherol content was variable, with greater variation in the concentration of α‐ and γ‐tocopherols than δ‐tocopherol. Phytosterol composition was markedly affected by genetic modification. Brassicasterol, campesterol, and β‐sitosterol levels were consistently lowered in one genotype, whereas increased brassicasterol content was observed in the other variety. In general, genetic modification of canola seeds led to changes in the distribution of phospholipids, tocopherols, and phytosterols.

29Si NMR and Small-Angle X-ray Scattering Studies of the Effect of Alkaline Ions (Li+, Na+, and K+) in Silico-Alkaline Sols

Alkali−silica reactions (ASR) which occur in concrete can be simulated in laboratory by destabilization of silico-alkaline aqueous solutions by addition of calcium ions. The relevant features of the reaction depend on the nature of alkaline ions (Li+, Na+, or K+) and on the silica/alkaline ratios which fix the distribution of the molecular species in the precursor solution. 29Si NMR spectroscopy and small-angle X-ray scattering (SAXS) techniques were used to study the structure and size distribution of molecular and colloidal species in sols with different silica/alkaline molar ratio and several types of alkaline ions. Experimental SAXS curves were simulated using a simple structural model which assumes the sol to be composed of a multimodal set of weakly interacting hard spheres immersed in a liquid matrix. The results indicate the existence of strong interactions between alkaline ion and hydroxide and between alkaline ion and silicate species. The formation of large species (cyclic molecules and colloidal particles) is enhanced in solutions containing lithium. These results are consistent with those of previous investigations.

Characterization of electrostatically self-assembled nanocomposite thin films

Multilayer thin films of metallic nanoclusters, polymers and other molecules have been formed using a novel electrostatic self-assembly method and analysed by multiple characterization techniques. Nanocluster size measurements, ellipsometry and UV-visible absorption spectroscopy have been used to confirm the linear build-up of the thin film thickness with the number of deposited nanocluster, polymer and other molecular layers. Auger electron spectroscopy allowed verification of the distribution of molecular species through thick films with multilayer segments containing different elements. Field emission scanning electron microscopy and atomic force microscopy permitted visualization of the morphologies of the outermost layers of the deposited films. Together, such characterization allows improved understanding and the basis for the design of multilayer thin film materials engineered to have specific molecular level structures and macroscopic functionalities.

Atomic and molecular emissions in the middle ultraviolet dayglow

Dayglow spectra in the middle ultraviolet, obtained during a sounding rocket flight from White Sands Missile Range in 1992, have been analyzed to determine the altitude distributions of thermospheric atomic and molecular species and to address a number of problems related to airglow excitation mechanisms. Among the atomic and molecular profiles retrieved are the N2 second positive, N2 Vegard‐Kaplan and NO gamma band systems, and the OI 297.2 nm, OII 247.0 nm, and NII 214.3 nm emissions. A self‐consistent study of the emission profiles was conducted by comparing observed intensities with one another and to forward models. Model photoelectron and photon fluxes were generated by the field line interhemispheric plasma model (FLIP) and two solar flux models. Neutral densities were obtained from mass‐spectrometer/incoherent scatter (MSIS)‐90. The results from the data analysis suggest that the major species' densities are within 40% of MSIS values. Evidence for the accuracy of the modeled densities and fluxes is seen in the close agreement between the calculated and observed intensities of the N2 second positive emission. Analysis of the OI 297.2 nm emission shows that the reaction N2(A) + O is the dominant source of O(1S) in the daytime thermosphere. The data imply that the vibrationally averaged yield of 0(1S) from the reaction is 0.43±0.12, which is smaller than the laboratory value measured for the N2(A, v′ = O) level. The cause of a disagreement between model and data for the Vegard‐Kaplan emission is unclear, but the discrepancy can be eliminated if the N2(A)+O quenching coefficient or the A state lifetime is increased by a factor between 2 and 4. The observed intensity of OII 247.0 nm is greater than expected by a factor of 2, implying possible inadequacies in the EUVAC and/or EUV91 solar models used in the analysis.

Quantitative analysis of ceramide molecular species by high performance liquid chromatography

A method was developed for quantitative analysis of molecular species of ceramide (N-acyl-sphingosine) and dihydroceramide (N-acyl sphinganine) by high performance liquid chromatography (HPLC). Various N-acyl chain-containing ceramides or dihydroceramides were semi-synthesized as standard materials and allowed to react with anthroyl cyanide, a fluorescent reagent. Anthroyl derivatives of ceramide and dihydroceramide containing C16, C18, C20, C22, and C24 saturated N-acyl chain could be completely separated to each molecular species by reversed-phase HPLC equipped with fluorescence detector, although some ceramide molecular species containing monoenoic acyl chain were eluted together with saturated dihydroceramide species. Ceramide molecular species could be quantified using N-heptadecanoyl or N-tricosanoyl sphingosine as an internal standard, and the lower detection limit was below 1 pmol. This method was applied to the analysis of sphingomyelin and free ceramide in U937 cells. The analysis of the ceramide obtained by hydrolysis of sphingomyelin of U937 cells revealed that the ceramide moiety was mainly composed of N-palmitoyl sphingosine, N-ner vonoyl sphingosine, and N-lignoceroyl sphingosine, representing 50.0, 27.4, and 6.7% of sphingomyelin, respectively. The total free ceramide and dihydroceramide of U937 cells was determined to be 254 ± 5 pmol/106 cells. Major molecular species of the free ceramide fraction were N-lignoceroyl, N-palmitoyl, and N-nerovonoyl sphingosine, representing 27.6%, 26.6%, and 13.6% of this fraction, respectively. Different distribution of free ceramide molecular species from sphingomyelin species may suggest that selective metabolism of molecular species occurs in the synthesis or degradation of sphingomyelin. These results indicate that the picomole level of molecular species of ceramide and dihydroceramide is successfully determined by fluorescence HPLC and that this newly developed method may be useful to reveal the metabolism and function of ceramide and related compounds in cultured cells.—Yano, M., E. Kishida, Y. Muneyuki, and Y. Masuzawa. Quantitative analysis of ceramide molecular species by high performance liquid chromatography. J. Lipid Res. 1998. 39: 2091–2098.

Direct structural observation of liquid molecules in single picoliter microdroplets using near-infrared Raman microprobe spectroscopy combined with laser trapping and chemical-tomographic imaging techniques

Two near-infrared (NIR) Raman microprobe spectroscopic techniques were developed for the direct structural observation of liquid molecules in single picoliter microdroplets. The use of NIR laser light as the excitation light source instead of visible laser light provides Raman spectra with lower fluorescence interference, which makes it easier to determine the structure of liquid molecules. Combining an NIR Raman microprobe with a laser trapping technique makes it possible to classify molecular species in a single picoliter microdroplet during laser trapping in solution. An NIR Raman microprobe chemical-tomographic (RMCT) imaging technique provides the three-dimensional distribution of molecular species in a picoliter microdroplet with a spatial resolution of several femtoliters in volume. Both techniques show sufficient sensitivity to obtain Raman spectra of liquid molecules in single picoliter microdroplets.

Two highly monounsaturated oils, olive oil and high-oleic sunflower oil, induce different triacylglycerol molecular species distribution in rat liver

Olive oil, but not high-oleic sunflower oil, is known to decrease blood pressure levels in patients with essential hypertension. Differences have been found in the minor component and triacylglycerol (TAG) contents. In order to determine whether differences are found in the content of liver lipids after administration of two monunsaturated oils from distinct sources, Wistar rats were fed with olive oil or high-oleic sunflower oil. Both oleic acid-rich oils caused similar effects on liver total lipids, phospholipids and cholesterol. When olive oil was administered to rats, the liver fatty acid content was also very similar to that of rats receiving high-oleic sunflower oil. However, olive oil intake resulted in a greater amount of dioleoylacylglycerol molecular species in rat liver, suggesting an increase in these species synthesis. This effect was not observed in rats consuming high-oleic sunflower oil, although the liver triacylglycerol pool was as high as that of rats receiving olive oil.