Quantitative and qualitative saccharide analysis of North Atlantic brown seaweed by gas chromatography/mass spectrometry and infrared spectroscopy

Brown seaweeds contain a variety of saccharides which have potential industrial uses. The most abundant polysaccharide in brown seaweed is typically alginate, consisting of mannuronic (M) and guluronic acid (G). The ratio of these residues fundamentally determines the physicochemical properties of alginate. In the present study, gas chromatography/mass spectrometry (GC/MS) was used to give a detailed breakdown of the monosaccharide species in North Atlantic brown seaweeds. The anthrone method was used for determination of crystalline cellulose. The experimental data was used to calibrate multivariate prediction models for estimation of total carbohydrates, crystalline cellulose, total alginate and alginate M/G ratio directly in dried, brown seaweed using three types of infrared spectroscopy, using relative error (RE) as a measure of predictive accuracy. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) performed well for the estimation of total alginate (RE = 0.12, R2 = 0.82), and attenuated total reflectance (ATR) showed good prediction of M/G ratio (RE = 0.14, R2 = 0.86). Both DRIFTS, ATR and near infrared (NIR) were unable to predict crystalline cellulose and only DRIFTS performed better in determining total carbohydrates. Multivariate spectral analysis is a promising method for easy and rapid characterization of alginate and M/G ratio in seaweed

Laccaria bicolor pectin methylesterases are involved in ectomycorrhiza development with Populus tremula x Populus tremuloides

The development of ectomycorrhizal (ECM) symbioses between soil fungi and tree roots requires modification of root cell walls. The pectin-mediated adhesion between adjacent root cells loosens to accommodate fungal hyphae in the Hartig net, facilitating nutrient exchange between partners. We investigated the role of fungal pectin modifying enzymes in Laccaria bicolor for ECM formation with Populus tremula x Populus tremuloides. We combine transcriptomics of cell-wall-related enzymes in both partners during ECM formation, immunolocalisation of pectin (Homogalacturonan, HG) epitopes in different methylesterification states, pectin methylesterase (PME) activity assays and functional analyses of transgenic L. bicolor to uncover pectin modification mechanisms and the requirement of fungal pectin methylesterases (LbPMEs) for ECM formation. Immunolocalisation identified remodelling of pectin towards de-esterified HG during ECM formation, which was accompanied by increased LbPME1 expression and PME activity. Overexpression or RNAi of the ECM-induced LbPME1 in transgenic L. bicolor lines led to reduced ECM formation. Hartig Nets formed with LbPME1 RNAi lines were shallower, whereas those formed with LbPME1 overexpressors were deeper. This suggests that LbPME1 plays a role in ECM formation potentially through HG de-esterification, which initiates loosening of adjacent root cells to facilitate Hartig net formation

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

MAGIC and H.E.S.S. detect VHE gamma rays from the blazar OT081 for the first time: a deep multiwavelength study

https://pos.sissa.it/395/815/pdfPublished versio

Functional studies of selected extracellular carbohydrate-active hydrolases in wood formation

Wood is an essential natural and renewable resource for human activities; e.g. paper and pulp industries, house construction and energy production. Wood cells such as fibers are fundamentally important cells whose morphology and chemical components influence the wood quality. They are formed in the vascular cambium and differentiate to maturity through cell elongation/expansion and deposition of secondary cell wall during the highly organized process of wood formation. Final cell morphology is largely determined by plasticity of its primary cell walls, while cell wall chemical composition is mainly determined during the secondary cell wall formation. These features are directly regulated by cell-wall residing enzymes, which modulate the cell wall components. Here I describe the functions of selected carbohydrate-active extracellular hydrolases including cellulases, a xylanase and a xyloglucan endotransglycosylase (XET), which are identified to be highly expressed at specific phases of wood formation in hybrid aspen (Populus tremula L. x Populus tremuloides Michx.). The XET PttXET16-34 is expressed during the primary cell wall stage and regulates cell growth by strengthening or weakening xyloglucan-cellulose microfibril networks. A putative xylanase, PttXyn10A, and a membrane anchored cellulase, PttCel9A1, are highly expressed during the secondary wall stage of xylem cell development. PttXyn10A may assist with the remaining fiber elongation at the early stage of secondary cell wall deposition by softening the walls by degrading xylans cross-linking to lignins. PttCel9A1 facilitates cellulose biosynthesis in a way that decreases cellulose crystallinity in cell walls, which is of great importance for the properties of cell wall structural framework. Thus, the elaboration of wood cells is performed through the well-coordinated biosynthesis and modification of chemical components, and through the diverse and dynamic actions of specific carbohydrate-active hydrolases. The understanding of these enzyme actions will lead to the improvement of wood characteristics to create biomaterials more applicable for different aspects of the forest industry

in Wood Formation

Wood is an essential natural and renewable resource for human activities; e.g. paper and pulp industries, house construction and energy production. Wood cells such as fibers are fundamentally important cells whose morphology and chemical components influence the wood quality. They are formed in the vascular cambium and differentiate to maturity through cell elongation/expansion and deposition of secondary cell wall during the highly organized process of wood formation. Final cell morphology is largely determined by plasticity of its primary cell walls, while cell wall chemical composition is mainly determined during the secondary cell wall formation. These features are directly regulated by cell-wall residing enzymes, which modulate the cell wall components. Here I describe the functions of selected carbohydrate-active extracellular hydrolases including cellulases, a xylanase and a xyloglucan endotransglycosylase (XET), which are identified to be highly expressed at specific phases of wood formation in hybrid aspen (Populus tremula L. x Populus tremuloides Michx.). The XET PttXET16-34 is expressed during the primary cell wall stage an

Intensity interferometry with the MAGIC telescopes

Due to their large mirror size, fast response to single photons, sensitivity and telescope baselines in the order of 100 m, Imaging Atmospheric Cherenkov Telescopes are ideally suited to perform intensity interferometry observations. In 2019 a test readout setup was installed in the two 17-m diameter MAGIC telescopes to allow performing interferometry measurements with them. The first on-sky measurements were able to detect correlated intensity fluctuations consistent with the stellar diameters of three different stars: Adhara (n CMa), Benetnasch ([ UMa) and Mirzam (V CMa). After the upgrade of the setup in 2021, MAGIC is now equipped with a high-duty-cycle intensity interferometer, already in operation. A technical description of the interferometer and first performance results obtained by measuring several known stellar diameter are presented

Extreme blazars under the eyes of MAGIC

Extreme high-frequency-peaked BL Lac objects (EHBLs) are the most energetic persistent sources in the universe. This contribution reports on long-term observing campaigns of tens of EHBLs that have been organized by the MAGIC collaboration to enlarge their population at VHE and understand the origin of their extreme properties. EHBLs are characterized by a spectral energy distribution (SED) featuring a synchrotron peak energy above 1 keV. Several EHBLs display a hard spectral index at very high energies (VHE; E > 100 GeV), suggesting a gamma-ray SED component peaking significantly above 1 TeV. Such extreme properties are challenging current standard emission and acceleration mechanisms. Recent studies have also unveiled intriguing disparities in the temporal characteristics of EHBLs. Some sources seem to display a persistent EHBL behaviour, while others belong to the EHBL family only temporarily. Here, we present recent results of the first hard-TeV EHBL catalog. The MAGIC observations are accompanied by an extensive multiwavelength coverage to obtain an optimal determination of the SED. This allow us to investigate leptonic and hadronic scenarios for the emission. We also present the recent detection of the EHBL RX J0812.0+0237 in the VHE band by MAGIC. Finally, we discuss a broad multiwavelength campaign on the BL Lac type object 1ES 2344+514, which showed intermittent EHBL characteristics in August 2016