Understanding plant cell-wall remodelling during the symbiotic interaction between Tuber melanosporum and Corylus avellana using a carbohydrate microarray.

MAIN CONCLUSION: A combined approach, using a carbohydrate microarray as a support for genomic data, has revealed subtle plant cell-wall remodelling during Tuber melanosporum and Corylus avellana interaction. Cell walls are involved, to a great extent, in mediating plant-microbe interactions. An important feature of these interactions concerns changes in the cell-wall composition during interaction with other organisms. In ectomycorrhizae, plant and fungal cell walls come into direct contact, and represent the interface between the two partners. However, very little information is available on the re-arrangement that could occur within the plant and fungal cell walls during ectomycorrhizal symbiosis. Taking advantage of the Comprehensive Microarray Polymer Profiling (CoMPP) technology, the current study has had the aim of monitoring the changes that take place in the plant cell wall in Corylus avellana roots during colonization by the ascomycetous ectomycorrhizal fungus T. melanosporum. Additionally, genes encoding putative plant cell-wall degrading enzymes (PCWDEs) have been identified in the T. melanosporum genome, and RT-qPCRs have been performed to verify the expression of selected genes in fully developed C. avellana/T. melanosporum ectomycorrhizae. A localized degradation of pectin seems to occur during fungal colonization, in agreement with the growth of the ectomycorrhizal fungus through the middle lamella and with the fungal gene expression of genes acting on these polysaccharides.

A simple Fourier filter for suppression of the missing wedge ray artefacts in single-axis electron tomographic reconstructions.

The limited specimen tilting range that is typically available in electron tomography gives rise to a region in the Fourier space of the reconstructed object where experimental data are unavailable - the missing wedge. Since this region is sharply delimited from the area of available data, the reconstructed signal is typically hampered by convolution with its impulse response, which gives rise to the well-known missing wedge artefacts in 3D reconstructions. Despite the recent progress in the field of reconstruction and regularization techniques, the missing wedge artefacts remain untreated in most current reconstruction workflows in structural biology. Therefore we have designed a simple Fourier angular filter that effectively suppresses the ray artefacts in the single-axis tilting projection acquisition scheme, making single-axis tomographic reconstructions easier to interpret in particular at low signal-to-noise ratio in acquired projections. The proposed filter can be easily incorporated into current electron tomographic reconstruction schemes.

Electron tomography of structures in the wall of hazel pollen grains.

The three-dimensional structure of channels and bacula cavities in the wall of hazel pollen grains was investigated by automated electron tomography in order to explore their role in the release of allergen proteins from the pollen grains. 3D reconstructions of 100-150 nm thick resin-embedded sections, stabilized by thin platinum-carbon coating, revealed that the channels aimed directly towards the surface of the grain and that the bacula cavities were randomly sized and merged into larger ensembles. The number and the dimensions of the ensembles were quantitatively determined by neighboring voxel analysis on thresholded reconstructed volumes. To simulate the allergen release, allergen proteins were approximated by a hard sphere model of a diameter corresponding to the largest dimension of the known 3D structure of the major birch allergen, Bet v 1, whose amino acid sequence is highly similar to the amino acid sequence of the major hazel allergen, Cor a 1. The analysis of positions where the hard sphere fits into the resolved channels and bacula cavity structures revealed that unbound allergens could freely traverse through the channels and that the bacula cavities support the path of the allergens towards the surface of the grain.

Effect of co-combustion on the burnout of lignite/biomass blends: a Turkish case study.

Co-combustion of Turkish Elbistan lignite and woody shells of hazelnut was performed in a TGA up to 1173 K with a heating rate of 20 K/min. SEM images of each fuel revealed the differences in their physical appearances. Hazelnut shell was blended with lignite in the range of 2-20 wt% to observe the co-combustion properties. Maximum burning rates (Rmax), temperatures of the maximum burning rates (T(R-max)), and the final burnout values of the parent samples and the blends were compared. The results were interpreted considering lignite properties and the major biomass ingredients such as cellulosics, hemicellulosics, and lignin. Deviations between the theoretical and experimental burnout values were evaluated at various temperatures. Burnout characteristics of the blends up to 10 wt% were concluded to have a synergistic effect so the addition of hazelnut shell up to 8 wt% provided higher burnouts than the expected theoretical ones, whereas addition of as much as 10 wt% led to a decrease in the burnout. However, the additive effects were more favorable for the blend having a biomass content of 20 wt%. Apparent activation energy, Rmax, and T(R-max), were found to follow the additive behavior for the blend samples.