Département sciences pour l'ingénierie des aliments, des produits biosourcés et des résidus de l'activité humaine

DISCO, a novel low-energy beamline covering the spectrum range from the VUV to the visible, has received its first photons at the French synchrotron SOLEIL. In this article the DISCO design and concept of three experimental stations serving research communities in biology and chemistry are described. Emphasis has been put on high flux generation and preservation of polarization at variable energy resolutions. The three experiments include a completely new approach for microscopy and atmospheric pressure experiments as well as a ;classical' synchrotron radiation circular dichroism station. Preliminary tests of the optical design and technical concept have been made. Theoretical predictions of the beam have been compared with the first images produced by the first photons originating from the large-aperture bending-magnet source. Results are also reported concerning the cold finger used to absorb hard X-ray radiation in the central part of the synchrotron beam and to avoid heavy thermal load on the following optics. Wavelength selection using monochromators with different gratings for each experimental set-up as well as beam propagation and conditioning throughout the optical system are detailed. First photons comply very well with the theoretical calculations.

In the mouth, proline-rich proteins (PRP), which are major components of stimulated saliva, interact with tannins contained in food. We report in vitro interactions of the tannin epigallocatechin gallate (EgCG), with a basic salivary PRP, IB5, studied through electrospray ionization mass spectrometry (ESI-MS), small-angle X-ray scattering (SAXS), and dynamic light scattering (DLS). In dilute protein (IB5) solutions of low ionic strength (1 mM), the proteins repel each other, and the tannins bind to nonaggregated proteins. ESI-MS experiments determine the populations of nonaggregated proteins that have bound various numbers of tannin molecules. These populations match approximately the Poisson distribution for binding to n = 8 sites on the protein. MS/MS experiments confirm that complexes containing n = 1 to 8 EgCG molecules are dissociated with the same energy. Assuming that the 8 sites are equivalent, we calculate a binding isotherm, with a binding free energy Δμ = 7.26RT(a) (K(d) = 706 μM). In protein solutions that are more concentrated (0.21 mM) and at higher ionic strength (50 mM, pH 5.5), the tannins can bridge the proteins together. DLS experiments measure the number of proteins per aggregate. This number rises rapidly when the EgCG concentration exceeds a threshold (0.2 mM EgCG for 0.21 mM of IB5). SAXS experiments indicate that the aggregates have a core-corona structure. The core contains proteins that have bound at least 3 tannins and the corona has proteins with fewer bound tannins. These aggregates coexist with nonaggregated proteins. Increasing the tannin concentration beyond the threshold causes the transfer of proteins to the aggregates and a fast rise of the number of proteins per aggregate. A poisoned growth model explains this fast rise. Very large cationic aggregates, containing up to 10,000 proteins, are formed at tannin concentrations (2 mM) slightly above the aggregation threshold (0.2 mM).

1. The aim of the experiment was to establish relationships between chemical or physical characteristics of wheats (Triticum aestivum) and digestibilities of food components in broiler chickens fed on wheat-based diets. Twenty-two wheat samples, each differing by their cultivar origin, were included at 550 g/kg in diets offered to male Ross broiler chicks. The other main ingredients were soya bean meal (340 g/kg) and rapeseed oil (68.5 g/kg). Diets were given as pellets. 2. In vitro viscosities of wheats measured as potential applied viscosity (PAV) or real applied viscosity (RAV) varied between 1.91 and 6.03, or between 0.95 and 3.81 ml/g (dry matter basis), respectively. Hardness of wheats varied between 17 (soft) and 95 (very hard), and lipase activity of wheats varied from 1 to 13.6 (relative scale). 3. PAV and RAV values were not significantly correlated with hardness. PAV and RAV values were correlated with (80:20) ethanol:water insoluble, water soluble arabinoxylans (r = 0.961, 0.932, respectively), with the amount of water retained by cell walls (r = 0.656, 0.492, respectively), and with lipase activity (r = 0.600, 0.532, respectively. 4. Hardness was correlated with ash (r = -0.484), nitrogen (r = 0.534), mean particle size of wheat flours (r = 0.631), and specific energy of pelleting (r = -0.574). 5. Wheat diets were evaluated in two assays with 3-week-old chicks, with 11 diets per assay. In each assay, a balance experiment was carried out using the total collection method. Growth performance was also measured during the balance experiment. 6. In vitro viscosity parameters were negatively correlated with diet AMEn (P < 0.05), lipid digestibility (P < 0.05) and, to a lesser extent, protein digestibility (P < 0.05). In vitro viscosity data were positively correlated with food:gain ratio (P < 0.05) and water loss parameters (P < 0.05), and were not significantly (P > 0.05) correlated with starch digestibility. 7. Wheat hardness-related parameters were correlated (P < 0.01) with individual starch digestibility (hardness, proportion of coarse particles in wheat flour, specific energy of pelleting: r = -0.273, -0.305, 0.212, respectively). 8. Wheat lipase activity was negatively correlated with individual lipid (r = -0.179; P < 0.05) and starch (r = -0.225; P < 0.01) digestibilities and with individual diet AMEn (r = -0.266; P < 0.001). Individual diet AMEn values were correlated (r = 0.175) with the values calculated by the EU AMEn prediction equation (Fisher and McNab, 1987). Among the correlations observed between the individual measured AMEn:EU predicted AMEn ratio and wheat parameters (P < 0.05), the correlation obtained with wheat lipase was the highest (r = -0.195). The correlations with lipase could be explained in part by strong correlations between lipase and in vitro viscosity parameters.

We report lanthanide-based micelles integrating hypericin (Hyp) for X-ray-triggered photodynamic therapy (PDT). The lanthanide luminescence induced by X-ray irradiation excites the photosensitizer, which leads to the generation of singlet oxygen. This versatile approach can be extended to other photosensitizers or other types of liponanoparticles and can allow for magnetic resonance imaging (MRI) guidance.

RNase P is the essential activity removing 5′-leader sequences from transfer RNA precursors. RNase P was always associated with ribonucleoprotein complexes before the discovery of protein-only RNase P enzymes called PRORPs (PROteinaceous RNase P) in eukaryotes. Here we provide biophysical and functional data to understand the mode of action of PRORP enzymes. Activity assays and footprinting experiments show that the anticodon domain of transfer RNA is dispensable, whereas individual residues in D and TψC loops are essential for PRORP function. PRORP proteins are characterized in solution and a molecular envelope is derived from small-angle X-ray scattering. Conserved residues are shown to be involved in the binding of one zinc atom to PRORP. These results facilitate the elaboration of a model of the PRORP/transfer RNA interaction. The comparison with the ribonucleoprotein RNase P/transfer RNA complex suggests that transfer RNA recognition by PRORP proteins is similar to that by ribonucleoprotein RNase P. RNase P is a key enzyme implicated in transfer RNA maturation that removes the 5′-leader sequences from transfer RNA precursors. In this study, a biophysical characterization of a novel protein-only variant of RNase P, known as PRORP (PROteinaceous RNase P), reveals that transfer RNA recognition by PRORP is similar to that by ribonucleoprotein RNase P.

B-type oligomeric procyanidins in apples constitute an important source of polyphenols in the human diet. Their role in health is not known, although it is suggested that they generate beneficial bioactive compounds upon metabolization by the gut microbiota. During apple processing, procyanidins interact with cell-wall polysaccharides and form stable complexes. These interactions need to be taken into consideration in order to better assess the biological effects of fruit constituents. Our objectives were to evaluate the impact of these interactions on the microbial metabolization of cell walls and procyanidins, and to investigate the potential anti-inflammatory activity of the resulting metabolome, in addition to analyzing the taxonomical changes which the microbiota undergo. In vitro fermentation of three model apple matrices with microbiota from 4 healthy donors showed that the binding of procyanidins to cell-wall polysaccharides, whether covalently or non-covalently, substantially reduced procyanidin degradation. Although cell wall-unbound procyanidins negatively affected carbohydrate fermentation, they generated more hydroxyphenylvaleric acid than bound procyanidins, and increased the abundance of Adlercreutzia and Gordonibacter genera. The best results in terms of production of anti-inflammatory bioactive metabolites were observed from the apple matrix with no bonds between procyanidins and cell wall polysaccharides, although the matrix with non-covalent bonds was not far behind.

Gas phase VUV single-photon photoionization spectroscopy of electrospray-produced multiply protonated cytochrome c protein (12 kDa) has been performed by means of coupling a linear quadrupole ion trap with a synchrotron beamline. The thresholds for the ionization of the 8+ and 11+ charge state precursors to radical 9+ and 12+ species were measured to be 12.75 ± 0.10 and 13.51 ± 0.10 eV, respectively.

The new synchrotron-radiation circular-dichroism (SRCD) endstation on the UV-visible synchrotron beamline DISCO has been commissioned at the SOLEIL synchrotron. The design has been focused on preservation of a high degree of linear polarization at high flux and moderate resolving power covering the vacuum ultraviolet to visible spectral range (125-600 nm). The beam dimensions have been set to 4 mm × 4 mm at 1 nm bandwidth for lower sample degradation. The nitrogen-purged sample chamber fits three types of sample holders accommodating conventional round cell mounting, automated rotation of the samples, as well as a microfluidic set-up. Automated temperature-controlled data collection on microvolumes is now available to the biology and chemistry communities. Macromolecules including membrane proteins, soluble proteins, bio-nanotubes, sugars, DNA and RNAs are now routinely investigated.

Photoionization study of Kr+ and Xe+ ions with the combined use of a merged-beam set-up and an ion trap

Objective: To determine the micronutrient composition of fresh and boiled traditional green leafy vegetables (TGLVs).Design: Sixteen TGLVs categorised into cultivated and uncultivated vegetables were analysed for vitamin C (ascorbic acid [AA] and dehydroascorbate [DHAA]), β-carotene, lutein and minerals.Results: Basella alba had the highest AA (72 mg/100 g) content; Vernonia amygdalina (unwashed), had the highest β-carotene and lutein concentrations (14.1 and 29.0 mg/100 g, respectively); Amaranthus hybridus had the highest AA (43 mg/100 g) and β-carotene (9.3 mg/100 g) content, for cultivated sp. Celosia argentea had the highest Fe content; Zn content of all the vegetables was low, 0.4–2.6 mg/100 g. Cooking resulted in significant losses in AA content in all the samples, 19% in B. alba to 100% in Crassocephalum crepidioides. Carotenoid losses were observed in 10 samples and six samples had increased values of β-carotene (12% to 183%) and lutein (64% to double).Conclusion: Traditional green leafy vegetables studied were found to be rich in the micronutrients of interest, especially in carotenoids. Boiling of leafy vegetables, as traditionally done, led to considerable losses of the micronutrients. The micronutrient content of uncultivated leafy vegetables compared well with commonly cultivated species.

Mutations in human mitochondrial aminoacyl-tRNA synthetases are associated with a variety of neurodegenerative disorders. The effects of these mutations on the structure and function of the enzymes remain to be established. Here, we investigate six mutants of the aspartyl-tRNA synthetase correlated with leukoencephalopathies. Our integrated strategy, combining an ensemble of biochemical and biophysical approaches, reveals that mutants are diversely affected with respect to their solubility in cellular extracts and stability in solution, but not in architecture. Mutations with mild effects on solubility occur in patients as allelic combinations whereas those with strong effects on solubility or on aminoacylation are necessarily associated with a partially functional allele. The fact that all mutations show individual molecular and cellular signatures and affect amino acids only conserved in mammals, points towards an alternative function besides aminoacylation.

Wheat storage proteins, gliadins, were found to form in vitro condensates in 55% ethanol/water mixture by decreasing temperature. The possible role of this liquid-liquid phase separation (LLPS) process on the in vivo gliadins storage is elusive and remains to be explored. Here we use γ-gliadin as a model of wheat proteins to probe gliadins behavior in conditions near physiological conditions. Bioinformatic analyses suggest that γ-gliadin is a hybrid protein with N-terminal domain predicted to be disordered and C-terminal domain predicted to be ordered. Spectroscopic data highlight the disordered nature of γ-gliadin. We developed an in vitro approach consisting to first solubilize γ-gliadin in 55% ethanol (v/v) and to progressively decrease ethanol ratio in favor of increased aqueous solution. Our results show the ability of γ-gliadin to self-assemble into dynamic droplets through LLPS, with saturation concentrations ranging from 25.9 µM ± 0.85 µM (35% ethanol (v/v)) to 3.8 µM ± 0.1 µM (0% ethanol (v/v)). We demonstrate the importance of the predicted ordered C-terminal domain of γ-gliadin in the LLPS by highlighting the protein condensates transition from a liquid to a solid state under reducing conditions. We demonstrate by increasing ionic strength the role displayed by electrostatic interactions in the phase separation. We also show the importance of hydrogen bonds in this process. Finally, we discuss the importance of gliadins condensates in their accumulation and storage in the wheat seed.

Alcohol induced osteoporosis is characterized by a bone mass decrease and microarchitecture alterations. Having observed an excess in osteocyte apoptosis, we aimed to assess the bone tissue biochemistry, particularly in the osteocyte and its environment. For this purpose, we used a model of alcohol induced osteoporosis in rats. Bone sections of cortical bone were investigated using synchrotron UV-microspectrofluorescence at subcellular resolution. We show that bone present three fluorescence peaks at 305, 333 and 385 nm, respectively corresponding to tyrosine, tryptophan and collagen. We have determined that tyrosine/collagen and tryptophan/collagen ratios were higher in the strong alcohol consumption group. Tryptophan is related to the serotonin metabolism involved in bone formation, while tyrosine is involved in the activity of tyrosine kinases and phosphatases in osteocytes. Our experiment represents the first combined synchrotron UV microspectroscopy analysis of bone tissue with a quantitative biochemical characterization in the osteocyte and surrounding matrix performed separately.

Abstract DNA is effectively damaged by radiation, which can on the one hand lead to cancer and is on the other hand directly exploited in the treatment of tumor tissue. DNA strand breaks are already induced by photons having an energy below the ionization energy of DNA. At high photon energies, most of the DNA strand breaks are induced by low‐energy secondary electrons. In the present study we quantified photon and electron induced DNA strand breaks in four different 12mer oligonucleotides. They are irradiated directly with 8.44 eV vacuum ultraviolet (VUV) photons and 8.8 eV low energy electrons (LEE). By using Si instead of VUV transparent CaF 2 as a substrate the VUV exposure leads to an additional release of LEEs, which have a maximum energy of 3.6 eV and can significantly enhance strand break cross sections. Atomic force microscopy is used to visualize strand breaks on DNA origami platforms and to determine absolute values for the strand break cross sections. Upon irradiation with 8.44 eV photons all the investigated sequences show very similar strand break cross sections in the range of 1.7–2.3×10 −16 cm 2 . The strand break cross sections for LEE irradiation at 8.8 eV are one to two orders of magnitude larger than the ones for VUV photons, and a slight sequence dependence is observed. The sequence dependence is even more pronounced for LEEs with energies &lt;3.6 eV. The present results help to assess DNA damage by photons and electrons close to the ionization threshold.

Abstract Polycyclic aromatic hydrocarbons (PAHs) are key species in astrophysical environments in which vacuum ultraviolet (VUV) photons are present, such as star-forming regions. The interaction with these VUV photons governs the physical and chemical evolution of PAHs. Models show that only large species can survive. However, the actual molecular properties of large PAHs are poorly characterized and the ones included in models are only an extrapolation of the properties of small and medium-sized species. We discuss here experiments performed on trapped ions including some at the SOLEIL VUV beam line DESIRS. We focus on the case of the large dicoronylene cation, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi mathvariant="normal">C</mml:mi> <mml:mrow> <mml:mn>48</mml:mn> </mml:mrow> </mml:msub> <mml:msubsup> <mml:mi mathvariant="normal">H</mml:mi> <mml:mrow> <mml:mn>20</mml:mn> </mml:mrow> <mml:mo>+</mml:mo> </mml:msubsup> </mml:mrow> </mml:math> , and compare its behavior under VUV processing with that of smaller species. We suggest that C 2 H 2 is not a relevant channel in the fragmentation of large PAHs. Ionization is found to largely dominate fragmentation. In addition, we report evidence for a hydrogen dissociation channel through excited electronic states. Although this channel is minor, it is already effective below 13.6 eV and can significantly influence the stability of astro-PAHs. We emphasize that the competition between ionization and dissociation in large PAHs should be further evaluated for their use in astrophysical models.

Brachypodium distachyon is a non-domesticated cereal. Nonetheless, Brachypodium was recently introduced as a model plant for temperate cereals. This study compares grain starch metabolism in Brachypodium and barley (Hordeum vulgare). In Brachypodium, we identified and annotated 28 genes involved in starch metabolism and identified important motifs including transit peptides and putative carbohydrate-binding modules (CBMs) of the families CBM20, CBM45, CBM48, and CBM53. Starch content was markedly lower in Brachypodium grains (12%) compared to barley grains (47%). Brachypodium starch granules were doughnut shaped and bimodally distributed into distinct small B-type (2.5-10 µm) and very small C-type (0.5-2.5 µm) granules. Large A-type granules, typical of cereals, were absent. Starch-bound phosphate, important for starch degradation, was 2-fold lower in Brachypodium compared with barley indicating different requirements for starch mobilization. The amylopectin branch profiles were similar and the amylose content was only slightly higher compared with barley cv. Golden Promise. The crystallinity of Brachypodium starch granules was low (10%) compared to barley (20%) as determined by wide-angle X-ray scattering (WAXS) and molecular disorder was confirmed by differential scanning calorimetry (DSC). The expression profiles in grain for most genes were distinctly different for Brachypodium compared to barley, typically showing earlier decline during the course of development, which can explain the low starch content and differences in starch molecular structure and granule characteristics. High transitory starch levels were observed in leaves of Brachypodium (2.8% after 14h of light) compared to barley (1.9% after 14h of light). The data suggest important pre-domesticated features of cereals.

Clef UT : 000321298800048

Phosphorus (P) is an essential element for all forms of life and is applied as fertilizer in agriculture. The P availability for plants may be highly dependent on the chemical state of P in fertilizers and soils; however, the nature of this dependence remains obscure due to the limitations of generally applied wet chemical and instrumental analytical approaches. This paper focuses on recently developed infrared, Raman, ultraviolet and X-ray microspectroscopic techniques for the characterization of P in soil. Microspectroscopic techniques have the advantage that discrete P phases can be distinguished and characterized even if their mass fractions are very low. However, only small volumes of soil can be analyzed by microspectroscopic methods hence a combination of macro- and microspectroscopic techniques is a promising concept.

This work gives a comprehensive view of the surface acylation of cellulose nanocrystals (CNCs), as a tool to monitor Pickering emulsions. It investigates the impact of the grafted chain length and surface degree of substitution (DSsurf), on the type (direct or inverse) of such emulsions. CNC samples were prepared by grafting 10 different linear acyl groups containing 2 to 18 carbons, with reaction times from 30 min to 5 h to vary the DSsurf. The grafting was evaluated by FT-IR and 13C CP-MAS NMR spectroscopies. Whatever the DSSurf, CNCs grafted with linear acyl chains of 2 to 6 carbons led to the exclusive formation of direct oil-in-water (O/W) emulsions with hexadecane. Distinctively, both O/W and water-in-oil (W/O) emulsions could be obtained when the linear chain contained 8 carbons or more, at low and high DSSurf, respectively. By adjusting the length of the grafted chain, DSSurf and particles concentration, we were able to monitor the type of emulsion formed, droplet size and surface coverage at the oil/water interface.

Photoionization of a buckminsterfullerene ion is investigated using an ion trap and a merged beam setup coupled to synchrotron radiation beamlines and compared to theoretical calculations. Absolute measurements derived from the ion trap experiment allow discrepancies concerning the photoionization cross section of C60+ to be solved.