Multi-scale datasets for monitoring Mediterranean oak forests from optical remote sensing during the SENTHYMED/MEDOAK experiment in the north of Montpellier (France).

Mediterranean forests represent critical areas that are increasingly affected by the frequency of droughts and fires, anthropic activities and land use changes. Optical remote sensing data give access to several essential biodiversity variables, such as species traits (related to vegetation biophysical and biochemical composition), which can help to better understand the structure and functioning of these forests. However, their reliability highly depends on the scale of observation and the spectral configuration of the sensor. Thus, the objective of the SENTHYMED/MEDOAK experiment is to provide datasets from leaf to canopy scale in synchronization with remote sensing acquisitions obtained from multi-platform sensors having different spectral characteristics and spatial resolutions. Seven monthly data collections were performed between April and October 2021 (with a complementary one in June 2023) over two forests in the north of Montpellier, France, comprised of two oak endemic species with different phenological dynamics (evergreen: Quercus ilex and deciduous: Quercus pubescens) and a variability of canopy cover fractions (from dense to open canopy). These collections were coincident with satellite multispectral Sentinel-2 data and one with airborne hyperspectral AVIRIS-Next Generation data. In addition, satellite hyperspectral PRISMA and DESIS were also available for some dates. All these airborne and satellite data are provided from free online download websites. Eight datasets are presented in this paper from thirteen studied forest plots: (1) overstory and understory inventory, (2) 687 canopy plant area index from Li-COR plant canopy analyzers, (3) 1475 in situ spectral reflectances (oak canopy, trunk, grass, limestone, etc.) from ASD spectroradiometers, (4) 92 soil moistures and temperatures from IMKO and Campbell probes, (5) 747 leaf-clip optical data from SPAD and DUALEX sensors, (6) 2594 in-lab leaf directional-hemispherical reflectances and transmittances from ASD spectroradiometer coupled with an integrating sphere, (7) 747 in-lab measured leaf water and dry matter content, and additional leaf traits by inversion of the PROSPECT model and (8) UAV-borne LiDAR 3-D point clouds. These datasets can be useful for multi-scale and multi-temporal calibration/validation of high level satellite vegetation products such as species traits, for current and future imaging spectroscopic missions, and by fusing or comparing both multispectral and hyperspectral data. Other targeted applications can be forest 3-D modelling, biodiversity assessment, fire risk prevention and globally vegetation monitoring.

A new set of monoclonal antibodies directed to proline-rich and central regions of p53.

The p53 protein can adopt several conformations in cells--"latent," "active," or mutant--depending on cellular stress or mutations of the TP53 gene. Today, only a few antibodies discriminating these conformations are available. We produced three new anti-p53 monoclonal antibodies (MAbs) directed against epitopes of human p53. The H53C1 MAb recognizes an epitope located at the N-terminal part of the central region of p53 and can discriminate mutant from wild-type conformation. The H53C2 and H53C3 MAbs are against different epitopes within the proline-rich region of p53. Moreover, the H53C2 epitope is located in the second negative regulatory domain of p53 between residues 80 and 93. These MAbs can be used as new tools to study and modulate the cellular functions of p53.

Hydrolysis of pectins with different degrees and patterns of methylation by the endopolygalacturonase of Fusarium moniliforme.

The mode of action of the endopolygalacturonase from Fusarium moniliforme was studied towards a series of pectins with different amounts and distribution patterns of methyl-ester groups. The enzyme hydrolysed the linkages between two galacturonic acid residues according to a multi-chain attack mechanism, at least at the early stage of the reaction. The final percentage of hydrolysis decreased with increasing the degree of methylation. The distribution pattern of the methyl groups affected the rate of hydrolysis as well as the final percentage of hydrolysis, a blockwise distribution being more favourable than a random one. The final products, as analysed by mass spectrometry, included methyl-esterified oligogalacturonates. The detailed analysis of the structure of the oligomers showed that the enzyme was able to accommodate methylated galacturonic acid in its active site, but that methyl-esterification negatively affected the affinity of the enzyme.

Preliminary characterization of a new exo-beta-(1,4)-galactanase with transferase activity.

As a prerequisite to the study of the fine chemical structure of the branched region of pectin, an exo-beta-(1,4)-galactanase was purified from a commercial preparation (Pectinex AR). Purification was carried out by precipitation with 70% saturated ammonium sulfate, preparative electrofocusing, anion-exchange chromatography and affinity chromatography on cross-linked alginate. Exogalactanase specific activity was 992 nkat mg-1 and the enzyme was devoid of beta-(1,3)- or beta-(1,6)-galactanase, arabinanase, beta-D-galactosidase and alpha-L-arabinofuranosidade activities. Residual exopolygalacturonase activity represented 2.9% of the galactanase activity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing showed two close bands with molecular weights of 120,000 and 90,000 and pHi of 3.8 and 4.1, respectively. The enzyme acted in an exo manner and its activity was optimum at pH 3.5 and 60 degrees C. When incubated with galacto-oligosaccharides, new oligosaccharides with a higher degree of polymerization appeared, indicating the ability of the enzyme to transfer galactose residues.

Isolation and partial characterization of feruloylated oligosaccharides from maize bran.

Maize bran contains phenolic acids [approximately 4% dry matter; mainly ferulic acid (Fe) and also diferulic acid], heteroxylans (approximately 50%), and cellulose (approximately 20%), but is devoid of lignin. Treatment of maize pericarp with 0.05 M trifluoroacetic acid at 100 degrees C for 2 h released approximately 90% of the heteroxylans and approximately 90% of the ferulic acid and its esters. After fractionation of the products with Amberlite XAD-2 and Sephadex LH-20 three main feruloylated oligosaccharides (F3-F7) were isolated. They represented approximately 30% of the ferulic acid, and approximately 2% of the neutral sugars contained in the hydrolysis supernatant. The compositions of F7, F6, and F3 were Fe-Ara (1:1), Fe-Ara-Xyl (1:1:1), and Fe-Ara-Xyl-Gal (1:1:1:1), respectively. The structures of the three oligomers were determined using chemical methods (methylation, acetalation, reduction) and 13C NMR spectroscopy: F7 was 5-O-(trans-feruloyl)-L-Araf;F6 was O-beta-D-Xyl p-(1-->2)-[5-O-(trans-feruloyl)-L-Araf]; and F3 was O-L-Gal p-(1-->4)-O-D-Xyl p-(1-->2)-[5-O-(trans-feruloyl)-L- Araf]. F7 has been previously isolated from other monocots especially from wheat bran and soluble arabinoxylans from wheat flour; this is the first report of feruloylated oligosaccharides F6 and F3. Our results suggest that these oligomers are side-chain constituents of heteroxylans in maize bran. Ferulic acid is probably partly responsible for the insolubility of heteroxylans by coupling polysaccharide chains through ferulic acid dimers.