Direct Depolymerization Coupled to Liquid Extraction Surface Analysis-High-Resolution Mass Spectrometry for the Characterization of the Surface of Plant Tissues

The cuticle, the outermost layer covering the epidermis of most aerial organs of land plants, can have a heterogeneous composition even on the surface of the same organ. The main cuticle component is the polymer cutin which, depending on its chemical composition and structure, can have different biophysical properties. In this study, we introduce a new on-surface depolymerization method coupled to liquid extraction surface analysis (LESA) high-resolution mass spectrometry (HRMS) for a fast and spatially resolved chemical characterization of the cuticle of plant tissues. The method is composed of an on-surface saponification, followed by extraction with LESA using a chloroform-acetonitrile-water (49:49:2) mixture and direct HRMS detection. The method is also compared with LESA-HRMS without prior depolymerization for the analysis of the surface of the petals of Hibiscus richardsonii flowers, which have a ridged cuticle in the proximal region and a smooth cuticle in the distal region. We found that on-surface saponification is effective enough to depolymerize the cutin into its monomeric constituents thus allowing detection of compounds that were not otherwise accessible without a depolymerization step. The effect of the depolymerization procedure was more pronounced for the ridged/proximal cuticle, which is thicker and richer in epicuticular waxes compared with the cuticle in the smooth/distal region of the petal

Analysing photonic structures in plants.

The outer layers of a range of plant tissues, including flower petals, leaves and fruits, exhibit an intriguing variation of microscopic structures. Some of these structures include ordered periodic multilayers and diffraction gratings that give rise to interesting optical appearances. The colour arising from such structures is generally brighter than pigment-based colour. Here, we describe the main types of photonic structures found in plants and discuss the experimental approaches that can be used to analyse them. These experimental approaches allow identification of the physical mechanisms producing structural colours with a high degree of confidence

Direct Depolymerization Coupled to Liquid Extraction Surface Analysis-High-Resolution Mass Spectrometry for the Characterization of the Surface of Plant Tissues.

The cuticle, the outermost layer covering the epidermis of most aerial organs of land plants, can have a heterogeneous composition even on the surface of the same organ. The main cuticle component is the polymer cutin which, depending on its chemical composition and structure, can have different biophysical properties. In this study, we introduce a new on-surface depolymerization method coupled to liquid extraction surface analysis (LESA) high-resolution mass spectrometry (HRMS) for a fast and spatially resolved chemical characterization of the cuticle of plant tissues. The method is composed of an on-surface saponification, followed by extraction with LESA using a chloroform-acetonitrile-water (49:49:2) mixture and direct HRMS detection. The method is also compared with LESA-HRMS without prior depolymerization for the analysis of the surface of the petals of Hibiscus richardsonii flowers, which have a ridged cuticle in the proximal region and a smooth cuticle in the distal region. We found that on-surface saponification is effective enough to depolymerize the cutin into its monomeric constituents thus allowing detection of compounds that were not otherwise accessible without a depolymerization step. The effect of the depolymerization procedure was more pronounced for the ridged/proximal cuticle, which is thicker and richer in epicuticular waxes compared with the cuticle in the smooth/distal region of the petal.European Research Council (ERC consolidator grant 279405) the Herchel Smith fund the Gatsby Charitable Foundation BBSRC grant BB/P001157/

Direct surface analysis coupled to high-resolution mass spectrometry reveals heterogeneous composition of the cuticle of Hibiscus trionum petals.

Plant cuticle, which is the outermost layer covering the aerial parts of all plants including petals and leaves, can present a wide range of patterns that, combined with cell shape, can generate unique physical, mechanical, or optical properties. For example, arrays of regularly spaced nanoridges have been found on the dark (anthocyanin-rich) portion at the base of the petals of Hibiscus trionum. Those ridges act as a diffraction grating, producing an iridescent effect. Because the surface of the distal white region of the petals is smooth and noniridescent, a selective chemical characterization of the surface of the petals on different portions (i.e., ridged vs smooth) is needed to understand whether distinct cuticular patterns correlate with distinct chemical compositions of the cuticle. In the present study, a rapid screening method has been developed for the direct surface analysis of Hibiscus trionum petals using liquid extraction surface analysis (LESA) coupled with high-resolution mass spectrometry. The optimized method was used to characterize a wide range of plant metabolites and cuticle monomers on the upper (adaxial) surface of the petals on both the white/smooth and anthocyanic/ridged regions, and on the lower (abaxial) surface, which is entirely smooth. The main components detected on the surface of the petals are low-molecular-weight organic acids, sugars, and flavonoids. The ridged portion on the upper surface of the petal is enriched in long-chain fatty acids, which are constituents of the wax fraction of the cuticle. These compounds were not detected on the white/smooth region of the upper petal surface or on the smooth lower surface.The authors acknowledge support by the ERC grant 279405.This is the author accepted manuscript. The final version is available at http://dx.doi.org/10.1021/acs.analchem.5b0249

Evaluation par test simplifié in vivo de la chimiosensibilité du Plasmodium falciparum à la chloroquine et à l'amodiaquine dans le Sud du Cameroun

La sensibilité in vivo du #Plasmodium falciparum$à la chloroquine et à l'amodiaquine à la dose de 25 mg/kg per os en trois jours a été évaluée par six enquêtes effectuées en 1989 dans le Sud-Ouest du Cameroun. La prévalence plasmodiale chez les écoliers est de 75$ est présent dans 96 % des infections. Parmi 357 enfants traités à la chloroquine, 24 % sont porteurs de trophozoïtes au 3ème jour du traitement et 17 % au 7ème jour. Une résistance complète de type R III est observée dans 4 % des cas. Parmi les 55 enfants traités à l'amodiaquine, 13 % et 10 % sont trouvés porteurs de rares trophozoïtes à J3 ET J7. La signification de ces résultats est discutée. (Résumé d'auteur

Ultrastructure and optics of the prism-like petal epidermal cells of Eschscholzia californica (California poppy).

The petals of Eschscholzia californica (California poppy) are robust, pliable and typically coloured intensely orange or yellow owing to the presence of carotenoid pigments; they are also highly reflective at certain angles, producing a silky effect. To understand the mechanisms behind colour enhancement and reflectivity in California poppy, which represents a model species among early-divergent eudicots, we explored the development, ultrastructure, pigment composition and optical properties of the petals using light microscopy and electron microscopy combined with both spectrophotometry and goniometry. The elongated petal epidermal cells each possess a densely thickened prism-like ridge that is composed primarily of cell wall. The surface ridges strongly focus incident light onto the pigments, which are located in plastids at the cell base. Our results indicate that this highly unusual, deeply ridged surface structure not only enhances the deep colour response in this desert species, but also results in strongly angle-dependent 'silky' reflectivity that is anisotropic and mostly directional