Inactivation of Cronobacter sakazakii by blue light illumination and the resulting oxidative damage to fatty acids.

Blue light (BL) exerts an antimicrobial effect on pathogenic bacteria. It has been hypothesized that its bactericidal activity depends upon the generation of reactive oxygen species (such as anion superoxides) and the resultant cellular damage. However, some aspects of this hypothesis needed to be tested and investigated. Thus, the work conducted herein examined the molecular impact of BL treatment on Cronobacter sakazakii, an emerging foodborne pathogen. The results showed that BL exhibited an efficient bactericidal effect against C. sakazakii. Under a sublethal BL dose, both intracellular anion superoxides and malondialdehyde (a marker of oxidative stress) contents were increased gradually. Moreover, permeability of the outer membrane was increased by approximately 50%, indicating membrane damage. Further investigation revealed alterations to cellular fatty acid profiles, with a decrease and disappearance of unsaturated fatty acids, including C18:2, C16:1, and C18:1. These data indicate that bacterial lipids, especially unsaturated fatty acids, are important molecular targets of BL photo-oxidation. The transcriptional response of bacteria to BL was also studied, and it was found that three genes were upregulated, including genes encoding antioxidants. The current study contributes towards an improved understanding of the bactericidal mechanisms of BL and highlights the importance of lipid and membrane damage.

A comprehensive comparable study of the physiological properties of four microalgal species under different light wavelength conditions.

MAIN CONCLUSION: Microalgae treated with blue light have potential for production of human nutrition supplement and biofuel due to their higher biomass productivity and favorable fatty acid composition. Chlorella vulgaris, Chlorella pyrenoidosa, Scenedesmus quadricauda and Scenedesmus obliquus are representative green microalgae which are widely reported for algal production. In this study, we provide a systematic investigation of the biomass productivity, photosynthetic pigments, chlorophyll fluorescence and fatty acid content of the four green microalgae. The strains were grown in two primary monochromatic light wavelengths [red and blue LEDs (light emitting diode)], and in white LED conditions, respectively. Among them, blue LED light was determined as the best light for growth rate, followed by red LED and white LED. The chlorophyll generation was more sensitive to the monochromatic blue light. The polyunsaturated fatty acids (PUFAs) such as α-linolenic acid (18:3), which were perfect for human nutrition supplementation, showed high concentrations in these algae strains under blue LED. Collectively, the results indicate that the blue LED is suitable for various food, feed, and algal biofuel productions due to both biomass and fatty acid productivity.

Factors affecting the uncaging efficiency of 500 nm light-activatable BODIPY caging group.

Photoremovable protective groups, or caging groups, enable us to regulate the activities of bioactive molecules in living cells upon photoirradiation. Nevertheless, requirement of UV light for activating caging group is a significant limitation due to its cell toxicity and its poor tissue penetration. Our group previously reported a 500 nm light-activatable caging group based on BODIPY scaffold, however, its uncaging efficiency was lower than those of conventional caging groups. Here we show that the uncaging quantum yield (QY) of BODIPY caging group depends upon the driving force of photo-induced electron transfer (PeT). We also found that the uncaging QY increased in less polar solvents. We applied these findings to develop BODIPY-caged capsaicin, which is well localized to low-polarity intracellular compartments, as a tool to stimulate TRPV1 in live cells in response to blue-green light.

UVA irradiation of fatty acids and their oxidized products substantially increases their ability to generate singlet oxygen.

UVA radiation plays an important role for adverse reactions in human tissue. UVA penetrates epidermis and dermis of skin being absorbed by various biomolecules, especially endogenous photosensitizers. This may generate deleterious singlet oxygen ((1)O2) that oxidizes fatty acids in cell membranes, lipoproteins, and other lipid-containing structures such as the epidermal barrier. Indications exist that fatty acids are not only the target of (1)O2 but also act as potential photosensitizers under UVA irradiation, if already oxidized. Five different fatty acids in ethanol solution (stearic, oleic, linoleic, linolenic and arachidonic acid) were exposed to UVA radiation (355 nm, 100 mW) for 30 seconds. (1)O2 luminescence was detected time-resolved at 1270 nm and confirmed in spectrally-resolved experiments. The more double bonds fatty acids have the more (1)O2 photons were detected. In addition, fatty acids were continuously exposed to broadband UVA for up to 240 min. During that time span, UVA absorption and (1)O2 luminescence substantially increased with irradiation time, reached a maximum and decreased again. HPLC-MS analysis showed that the amount of peroxidized fatty acids and the (1)O2 generation increased and decreased in parallel. This indicates the high potential of peroxidized fatty acids to produce (1)O2 under UVA irradiation. In conclusion, fatty acids along with peroxidized products are weak endogenous photosensitizers but become strong photosensitizers under continuous UVA irradiation. Since fatty acids and their oxidized products are ubiquitous in living cells and in skin, which is frequently and long-lasting exposed to UVA radiation, this photosensitizing effect may contribute to initiation of deleterious photooxidative processes in tissue.

Stearoyl-acyl carrier protein desaturase gene from the oleaginous microalga Chlorella zofingiensis: cloning, characterization and transcriptional analysis.

The green alga Chlorella zofingiensis can accumulate high level of oleic acid (OA, C18:1△(9)) rich oils in response to stress conditions. To understand the regulation of biosynthesis of fatty acid in particular OA at the molecular level, we cloned and characterized the stearoyl acyl carrier protein (ACP) desaturase (SAD) responsible for OA formation through desaturation of stearic acid (C18:0) from C. zofingiensis. Southern blot indicated that the C. zofingiensis genome contained a single copy of SAD, from which the deduced amino acid sequence shared high identity to the corresponding homologs from other microalgae and higher plants. The desaturation activity of SAD was demonstrated in vitro using C18:0-ACP as a substrate. Stress conditions such as high light (HL), nitrogen deficiency (N(-)), or combination of HL and N(-) (HL + N(-)) drastically up-regulated the transcripts of biotin carboxylase (BC, a subunit of ACCase) and SAD, and therefore induced considerably the cellular accumulation of total fatty acids including OA. Glucose (50 mM) gave rise to the similar up-regulation of the two genes and induction of fatty acid accumulation. The accumulation of intracellular reactive oxygen species was found to be associated with the up-regulation of genes. This is the first report of characterization of Chlorella-derived SAD and the results may contribute to understanding of the mechanisms involved in fatty acid/lipid biosynthesis in microalgae.

Fatty acids and vitamins generate singlet oxygen under UVB irradiation.

UVB radiation is already known as initiator and promoter of carcinogenesis in skin. UVB is well absorbed in proteins and DNA leading to products such as cyclobutane pyrimidine dimers. In contrast, UVA radiation generates reactive oxygen species such as singlet oxygen, which can initiate a variety of cellular damages and cellular signalling. It was the goal to investigate whether and to which extent UVB radiation is additionally able to cause oxidative damages via singlet oxygen. Potential endogenous photosensitizers such as vitamin B molecules or unsaturated fatty acids were irradiated in solution using monochromatic UVB radiation at 308 nm. Singlet oxygen was directly detected and quantified by its luminescence at 1270 nm. All investigated endogenous photosensitizers showed clear singlet oxygen signals with a quantum yield ranging from 5 to 40%. UVB radiation altered the photosensitizer molecules during irradiation yielding a change of absorption in the entire ultraviolet spectrum (280-400 nm). UVB irradiation of endogenous photosensitizers produced singlet oxygen that in turn changes the absorption of those molecules. Being an important prerequisite, the changed absorption may either reduce or increase singlet oxygen production. An increase in singlet oxygen generation may initiate a vicious cycle that has the potential to amplify UVB- or UVA-mediated effects in skin cells.

The role of fatty acids in anti-inflammatory effects of low-intensity extremely high-frequency electromagnetic radiation.

The effects of low-intensity extremely high-frequency electromagnetic radiation (EHF EMR; 42.2 GHz, 0.1 mW/cm(2) , exposure duration 20 min) on the fatty acid (FA) composition of thymic cells and blood plasma in normal mice and in mice with peritoneal inflammation were studied. It was found that the exposure of normal mice to EHF EMR increased the content of polyunsaturated FAs (PUFAs) (eicosapentaenoic and docosapentaenoic) in thymic cells. Using a model of zymosan-induced peritoneal inflammation, it was shown that the exposure of mice to EHF EMR significantly increased the content of PUFAs (dihomo-γ-linolenic, arachidonic, eicosapentaenoic, docosapentaenoic, and docosahexaenoic) and reduced the content of monounsaturated FAs (MUFAs) (palmitoleic and oleic) in thymic cells. Changes in the FA composition in the blood plasma were less pronounced and manifested themselves as an increase in the level of saturated FAs during the inflammation. The data obtained support the notion that MUFAs are replaced by PUFAs that can enter into the thymic cells from the external media. Taking into account the fact that the metabolites of PUFAs are lipid messengers actively involved in inflammatory and immune reactions, we assume that the increase in the content of n-3 and n-6 PUFAs in phospholipids of cellular membranes facilitates the realization of anti-inflammatory effects of EHF EMR.

Sequential depletion of rat testicular lipids with long-chain and very long-chain polyenoic fatty acids after X-ray-induced interruption of spermatogenesis.

When a single dose of X-rays is applied to the adult rat testis, stem spermatogonia are damaged, and spermatogenesis is interrupted. Supported by Sertoli cells, spermatogenic cells that endure irradiation complete their differentiation and gradually leave the testis as spermatozoa. In this study, the in vivo changes taking place a number of weeks after irradiation revealed cell-specific features of testicular lipid classes. A linear drop, taking about six weeks, in testis weight, nonlipid materials, free cholesterol, and 22:5n-6-rich glycerophospholipids took place with germ cell depletion. Sphingomyelins and ceramides with nonhydroxy very long-chain polyenoic fatty acids (n-VLCPUFA) disappeared in four weeks, together with the last spermatocytes, whereas species with 2-hydroxy VLCPUFA lasted for six weeks, disappearing with the last spermatids and spermatozoa. The amount per testis of 22:5n-6-rich triacylglycerols, unchanged for four weeks, fell between weeks 4 and 6, associating these lipids with spermatids and their residual bodies, detected as small, bright lipid droplets. In contrast, 22:5n-6-rich species of cholesterol esters and large lipid droplets increased in seminiferous tubules up to week 6, revealing they are Sertoli cell products. At week 30, the lipid and fatty acid profiles reflected the resulting permanent testicular involution. Our data highlight the importance of Sertoli cells in maintaining lipid homeostasis during normal spermatogenesis.

Synergistic effects of binary oil mixtures on the solubility of sunscreen UV absorbers.

Sunscreens for the photoprotection of human skin often are prepared as emulsions, containing organic UV-absorber molecules dissolved in the oil phase. The solubility of such oil-soluble UV-absorbers can be a limiting factor when aiming for high protection against UV-radiation. Possible synergistic effects of combinations of oil components toward UV-absorber solubility are therefore of great interest. Since a multitude of different combinations of oil components are possible, it would be desirable to predict synergistic effects by computational methods. As a model system, the solubility of a hydroxyphenyl triazine type UV-absorber was studied in several binary oil mixtures, experimentally and also by using a computational procedure based on density functional theory (DFT) and the continuum solvation model COSMO-RS. We have found good agreement of experimental and computational results. Computational methods may thus be employed to predict synergistic behaviour of solubility for systems containing two or more solvents.

The effective atomic numbers of some biomolecules calculated by two methods: a comparative study.

The effective atomic numbers Z(eff) of some fatty acids and amino acids have been calculated by two numerical methods, a direct method and an interpolation method, in the energy range of 1 keV-20 MeV. The notion of Z(eff) is given a new meaning by using a modern database of photon interaction cross sections (WinXCom). The results of the two methods are compared and discussed. It is shown that for all biomolecules the direct method gives larger values of Z(eff) than the interpolation method, in particular at low energies (1-100 keV) At medium energies (0.1-5 MeV), Z(eff) for both methods is about constant and equal to the mean atomic number of the material. Wherever possible, the calculated values of Z(eff) are compared with experimental data.

Effect of gamma-irradiation on membrane fatty acids and peptidoglycan's muropeptides of Pantoea agglomerans, a plant pathogen.

AIMS: The aim of this study was to evaluate the effect of gamma-irradiation on the fatty acids (FA) and muropeptides content of two strains of an Enterobacteriacea: Pantoea agglomerans. METHODS AND RESULTS: Pantoea agglomerans strains ATCC 49174 and RL1 isolated from irradiated carrots were used for this study. Radiation treatments (1 and 3.5 kGy) were performed to study the radiotolerance. Total lipids were obtained by multiple extractions using methanol/chloroform (2 : 1) and were quantified by GC. Muropeptides were purified by successive enzymatic digestions and analysed using a reverse phase C(18) column in high performance liquid chromatography. A significant (P

The ultrasound-assisted oxidative scission of monoenic fatty acids by ruthenium tetroxide catalysis: influence of the mixture of solvents.

Carboxylic acids and diacids were synthesized from monoenic fatty acids by using RuO4 catalysis, under ultrasonic irradiation, in various mixtures of solvents. Ultrasound associated with Aliquat 336 have promoted in water, the quantitative oxidative cleavage of the CH=CH bond of oleic acid. A design of experiment (DOE) shows that the optimal mixture of solvents (H2O/MeCN, ratio 1/1, 2.2% RuCl3/4.1 eq. NaIO4) gives 81% azelaic acid and 97% pelargonic acid. With the binary heterogeneous mixture H2O/AcOEt, the oxidation of the oleic acid leads to a third product, the alpha-dione 9,10-dioxostearic acid.

The kinetics of photocatalytic degradation of aliphatic carboxylic acids in an UV/TiO2 suspension system.

Kinetic studies on the photocatalytic degradation of aliphatic carboxylic acids were carried out in a slurry photoreactor with in-situ monitoring, employing artificial UV light as the source of energy and nano-TiO2 powder as the catalyst. The influences on the photocatalytic degradation such as the initial concentration of reactant (C0), catalyst dosage (CTiO2), UV intensity (Ia) and pH value have been investigated. Good agreement has been obtained between the value calculated by Langmuir-Freundlich-Hinshelwood (L-F-H) model and experimental data, with coefficient of multiple determination (R2) varying from 0.880 to 0.999. The L-F-H model has been proven to be feasible in describing the kinetic characteristic of the photocatalytic degradation of aliphatic carboxylic acids. Moreover, the apparent reaction rate constant (k) of the photocatalytic degradation of dicarboxylic acids is higher than that of monocarboxylic acids with the same carbon atoms. This shows that the photocatalytic degradation rate is favoured by different chemical structure.

Addition of Sesamol Increases the Oxidative Stability of Beeswax Organogels and Beef Tallow Matrix Under UV Light Irradiation and Thermal Oxidation.

To enhance the oxidative stability of organogels made from canola oil, 40 ppm sesamol was added to beeswax-based organogels stored under ultraviolet (UV) light irradiation and 60 or 100 °C thermal oxidation conditions. To study the practical application of organogels as animal fat substitutes, beef tallow was mixed with organogels and their oxidative stability was determined under oxidative stress conditions. Without sesamol addition, the organogels and beef tallow with organogel oxidized rapidly under UV irradiation and thermal oxidation. The addition of 40-ppm sesamol decreased the consumption of headspace oxygen and the formation of primary and secondary oxidation products significantly (P < 0.05) compared with those in samples without the addition of sesamol, irrespective of oxidative stress. Sesamol improved the oxidative stability of organogels and beef tallow with organogel, which could be used in the meat industry. PRACTICAL APPLICATION: Organogels may replace trans-fat or highly saturated lipids in food products. The high degree of unsaturation and processing temperature mean that antioxidants are needed to extend the shelf life of organogels or organogel-containing products. The addition of sesamol significantly enhanced the oxidative stability of organogels and of beef tallow-containing organogels under UV irradiation and thermal oxidation conditions. Therefore, sesamol-supplemented organogels could replace saturated fats in beef tallow and prolong the shelf-life of meat products.

Photo-triggered conversion of hydrophilic fluorescent biomimetic nanostructures for cell imaging.

Fluorescent nanoarchitectures, such as hydrophobic micelles and hydrophilic vesicles decorated with fluorescent carbon nanoparticles, were fabricated from one fatty acid by means of photo-triggering. The biomimetic nanostructures, like cell membrane structures, have applications in fluorescence imaging in both the cell cytoplasm and nucleus. Besides, hydrophobic micelles can be used as very stable fluorescent inks.

Optical detection of singlet oxygen produced by fatty acids and phospholipids under ultraviolet A irradiation.

Ultraviolet A (UVA) radiation has been known to generate reactive oxygen species, such as singlet oxygen, in skin, leading to the oxidation of lipids and proteins. This oxidation influences cellular metabolism and can trigger cellular signaling cascades, since cellular membranes and the stratum corneum contain a substantial amount of fatty acids and lipids. Using highly sensitive IR-photomultiplier technology, we investigated the generation of singlet oxygen by fatty acids and lipids. In combination with their oxidized products, the fatty acids or lipids produced singlet oxygen under UVA radiation at 355 nm that is directly shown by luminescence detection. Linolenic or arachidonic acid showed the strongest luminescence signals, followed by linoleic acid and docohexaenoic acid. The amount of singlet oxygen induced by lipids such as phosphatidylcholine was significantly higher compared to the corresponding fatty acids within phospholipids. This result indicates a synergistic process of oxygen radicals and singlet oxygen during irradiation. UVA radiation initiates singlet oxygen generation, which subsequently oxidizes other fatty acids that in turn produce additional singlet oxygen. This leads to an enhancement of UVA-induced damage of fatty acids and lipids, which must enhance the oxidative damages in cells.

Spectral monitoring of photoirradiated skin lipids: MS and IR approaches.

An investigation of the effects of UV(A) irradiation on the stratum corneum lipids was carried out in vitro on films. The modifications of their conformational order were studied by FTIR and the formation of new entities was detected by mass spectroscopy. The results show not only differences in behaviour of the three lipid classes (fatty acids (FA), ceramides (CER), and cholesterol), but also variation within a class, depending on the molecules structure. Upon UV(A) irradiation, beta scission occurs on all the components, saturated and unsaturated. Moreover, unsaturated FA or CER having a double bond on their FA moiety may become saturated or may be transformed into their free radical form. Unsaturated FA are more sensitive to UV(A) and lead more easily to oxygenated components than unsaturated CER. The chemical effects are irradiation dose dependent but do not deeply influence the supramolecular organisation of these lipids. The global conformation of the lipids stays in an orthorhombic state, a decrease of the packing density however is observed.

Studies on effective atomic number, electron density and kerma for some fatty acids and carbohydrates.

The effective atomic number, Z(eff), the effective electron density, N(el), and kerma have been calculated for some fatty acids and carbohydrates for photon interaction in the extended energy range from 1 keV to 100 GeV using an accurate database of photon-interaction cross sections and the WinXCom program. The significant variation of Z(eff) and N(el) is due to the variations in the dominance of different interaction processes in different energy regions. The maximum values of Z(eff) and N(el) are found in the low-energy range, where photoelectric absorption is the main interaction process. The minimum values of Z(eff) and N(el) are found at intermediate energies, typically 0.05 MeV < E < 5 MeV, where Compton scattering is dominant. In this case, Z(eff) is equal to the mean atomic number of the bio-molecule. Wherever possible, the calculations are compared with experimental results. A comparison is also made with the single values of the Z(eff) and N(el) provided by the program XMuDat. It is also observed that carbohydrates have a larger kerma than fatty acids in the low-energy region, where photoelectric absorption dominates. In contrast, fatty acids have a larger kerma than carbohydrates in the MeV range, where Compton scattering is the main interaction process.

Influence of bleaching by ultrasound on fatty acids and minor compounds of olive oil. Qualitative and quantitative analysis of volatile compounds (by SPME coupled to GC/MS).

The effects of bleaching using high power ultrasound (20 kHz) on the quality of olive oil were considered in this study, in order to verify the modifications that can occur in fatty acid composition and minor compounds. During the treatment of olive oil under ultrasonic waves, a rancid odour has been detected. Treated olive oils show no significant changes in their chemical composition but the presence of some volatile compounds, due to ultrasonic treatment. Some off-flavour compounds (hexanal, hept-2-enal and 2(E),4(E)-decadienal) resulting from the sonodegradation of olive oil have been identified. A wide variety of analytical techniques (GLC, HPLC and GC/MS) were used to follow the quality of bleached olive oils with ultrasonic waves by the determination of the amounts of certain minor compounds such as sterols and tocopherols. Steradienes, resulting from the dehydration of sterols, were detected with small quantities especially in severe conditions of sonication. Solid phase micro-extraction (SPME) coupled to gas chromatography was known to be a sensitive technique to follow changes in the oxidative state of vegetable oils by measuring the amount of volatile materials produced during the refining process.

Hippocampal lipidome and transcriptome profile alterations triggered by acute exposure of mice to GSM 1800 MHz mobile phone radiation: An exploratory study.

BACKGROUND: The widespread use of wireless devices during the last decades is raising concerns about adverse health effects of the radiofrequency electromagnetic radiation (RF-EMR) emitted from these devices. Recent research is focusing on unraveling the underlying mechanisms of RF-EMR and potential cellular targets. The "omics" high-throughput approaches are powerful tools to investigate the global effects of RF-EMR on cellular physiology. METHODS: In this work, C57BL/6 adult male mice were whole-body exposed (nExp  = 8) for 2 hr to GSM 1800 MHz mobile phone radiation at an average electric field intensity range of 4.3-17.5 V/m or sham-exposed (nSE  = 8), and the RF-EMR effects on the hippocampal lipidome and transcriptome profiles were assessed 6 hr later. RESULTS: The data analysis of the phospholipid fatty acid residues revealed that the levels of four fatty acids [16:0, 16:1 (6c + 7c), 18:1 9c, eicosapentaenoic acid omega-3 (EPA, 20:5 ω3)] and the two fatty acid sums of saturated and monounsaturated fatty acids (SFA and MUFA) were significantly altered (p < 0.05) in the exposed group. The observed changes indicate a membrane remodeling response of the tissue phospholipids after nonionizing radiation exposure, reducing SFA and EPA, while increasing MUFA residues. The microarray data analysis demonstrated that the expression of 178 genes changed significantly (p < 0.05) between the two groups, revealing an impact on genes involved in critical biological processes, such as cell cycle, DNA replication and repair, cell death, cell signaling, nervous system development and function, immune system response, lipid metabolism, and carcinogenesis. CONCLUSIONS: This study provides preliminary evidence that mobile phone radiation induces hippocampal lipidome and transcriptome changes that may explain the brain proteome changes and memory deficits previously shown by our group.