Glycosyltransferase family 47 (GT47) proteins in plants and animals.

Glycosyltransferases (GTs) are carbohydrate-active enzymes that are encoded by the genomes of organisms spanning all domains of life. GTs catalyze glycosidic bond formation, transferring a sugar monomer from an activated donor to an acceptor substrate, often another saccharide. GTs from family 47 (GT47, PF03016) are involved in the synthesis of complex glycoproteins in mammals and insects and play a major role in the synthesis of almost every class of polysaccharide in plants, with the exception of cellulose, callose, and mixed linkage ß-1,3/1,4-glucan. GT47 enzymes adopt a GT-B fold and catalyze the formation of glycosidic bonds through an inverting mechanism. Unlike animal genomes, which encode few GT47 enzymes, plant genomes contain 30 or more diverse GT47 coding sequences. Our current knowledge of the GT47 family across plant species brings us an interesting view, showcasing how members exhibit a great diversity in both donor and acceptor substrate specificity, even for members that are classified in the same phylogenetic clade. Thus, we discuss how plant GT47 family members represent a great case to study the relationship between substrate specificity, protein structure, and protein evolution. Most of the plant GT47 enzymes that are identified to date are involved in biosynthesis of plant cell wall polysaccharides, including xyloglucan, xylan, mannan, and pectins. This indicates unique and crucial roles of plant GT47 enzymes in cell wall formation. The aim of this review is to summarize findings about GT47 enzymes and highlight new challenges and approaches on the horizon to study this family.

An update on xylan structure, biosynthesis, and potential commercial applications.

•Xylan is an abundant carbohydrate component of plant cell walls that is vital for proper cell wall structure and vascular tissue development.•Xylan structure is known to vary between different tissues and species.•The role of xylan in the plant cell wall is to interact with cellulose, lignin, and hemicelluloses.•Xylan synthesis is directed by several types of Golgi-localized enzymes.•Xylan is being explored as an eco-friendly resource for diverse commercial applications.

Enzymatic Synthesis of Xylan Microparticles with Tunable Morphologies.

Xylans are a diverse family of hemicellulosic polysaccharides found in abundance within the cell walls of nearly all flowering plants. Unfortunately, naturally occurring xylans are highly heterogeneous, limiting studies of their synthesis and structure-function relationships. Here, we demonstrate that xylan synthase 1 from the charophyte alga Klebsormidium flaccidum is a powerful biocatalytic tool for the bottom-up synthesis of pure ß-1,4 xylan polymers that self-assemble into microparticles in vitro. Using uridine diphosphate-xylose (UDP-xylose) and defined saccharide primers as substrates, we demonstrate that the shape, composition, and properties of the self-assembling xylan microparticles could be readily controlled via the fine structure of the xylan oligosaccharide primer used to initiate polymer elongation. Furthermore, we highlight two approaches for bottom-up and surface functionalization of xylan microparticles with chemical probes and explore the susceptibility of xylan microparticles to enzymatic hydrolysis. Together, these results provide a useful platform for structural and functional studies of xylans to investigate cell wall biosynthesis and polymer-polymer interactions and suggest possible routes to new biobased materials with favorable properties for biomedical and renewable applications.

Protocols for isolating and characterizing polysaccharides from plant cell walls: a case study using rhamnogalacturonan-II.

BACKGROUND: In plants, a large diversity of polysaccharides comprise the cell wall. Each major type of plant cell wall polysaccharide, including cellulose, hemicellulose, and pectin, has distinct structures and functions that contribute to wall mechanics and influence plant morphogenesis. In recent years, pectin valorization has attracted much attention due to its expanding roles in biomass deconstruction, food and material science, and environmental remediation. However, pectin utilization has been limited by our incomplete knowledge of its structure. Herein, we present a workflow of principles relevant for the characterization of polysaccharide primary structure using nature's most complex polysaccharide, rhamnogalacturonan-II (RG-II), as a model. RESULTS: We outline how to isolate RG-II from celery and duckweed cell walls and from red wine using chemical or enzymatic treatments coupled with size-exclusion chromatography. From there, we applied mass spectrometry (MS)-based techniques to determine the glycosyl residue and linkage compositions of the intact RG-II and derived oligosaccharides including special considerations for labile monosaccharides. In doing so, we demonstrated that in the duckweed Wolffiella repanda the arabinopyranosyl (Arap) residue of side chain B is substituted at O-2 with rhamnose. We used electrospray-MS techniques to identify non-glycosyl modifications including methyl-ethers, methyl-esters, and acetyl-esters on RG-II-derived oligosaccharides. We then showed the utility of proton nuclear magnetic resonance spectroscopy (1H-NMR) to investigate the structure of intact RG-II and to complement the RG-II dimerization studies performed using size-exclusion chromatography. CONCLUSIONS: The complexity of pectic polysaccharide structures has hampered efforts aimed at their valorization. In this work, we used RG-II as a model to demonstrate the steps necessary to isolate and characterize polysaccharides using chromatographic, MS, and NMR techniques. The principles can be applied to the characterization of other saccharide structures and will help inform researchers on how saccharide structure relates to functional properties in the future.

AtFUT4 and AtFUT6 Are Arabinofuranose-Specific Fucosyltransferases.

The bulk of plant biomass is comprised of plant cell walls, which are complex polymeric networks, composed of diverse polysaccharides, proteins, polyphenolics, and hydroxyproline-rich glycoproteins (HRGPs). Glycosyltransferases (GTs) work together to synthesize the saccharide components of the plant cell wall. The Arabidopsis thaliana fucosyltransferases (FUTs), AtFUT4, and AtFUT6, are members of the plant-specific GT family 37 (GT37). AtFUT4 and AtFUT6 transfer fucose (Fuc) onto arabinose (Ara) residues of arabinogalactan (AG) proteins (AGPs) and have been postulated to be non-redundant AGP-specific FUTs. AtFUT4 and AtFUT6 were recombinantly expressed in mammalian HEK293 cells and purified for biochemical analysis. We report an updated understanding on the specificities of AtFUT4 and AtFUT6 that are involved in the synthesis of wall localized AGPs. Our findings suggest that they are selective enzymes that can utilize various arabinogalactan (AG)-like and non-AG-like oligosaccharide acceptors, and only require a free, terminal arabinofuranose. We also report with GUS promoter-reporter gene studies that AtFUT4 and AtFUT6 gene expression is sub-localized in different parts of developing A. thaliana roots.

Mechanism and Reaction Energy Landscape for Apiose Cross-Linking by Boric Acid in Rhamnogalacturonan II.

Rhamnogalacturonan II (RG-II)-the most complex polysaccharide known in nature-exists as a borate cross-linked dimer in the plant primary cell wall. Boric acid facilitates the formation of this cross-link on the apiosyl residues of RG-II's side chain A. Here, we detail the reaction mechanism for the cross-linking process with ab initio calculations coupled with transition state theory. We determine the formation of the first ester linkage to be the rate-limiting step of the mechanism. Our findings demonstrate that the regio- and stereospecific nature of subsequent steps in the reaction itinerary presents four distinct energetically plausible reaction pathways. This has significant implications for the overall structure of the cross-linked RG-II dimer assembly. Our transition state and reaction path analyses reveal key geometric insights that corroborate previous experimental hypotheses on borate ester formation reactions.

Bond reactivity indices approach analysis of the [2+2] cycloaddition of jatrophane skeleton diterpenoids from Euphorbia gaditana Coss to tetracyclic gaditanone.

The reaction mechanism of the intramolecular [2 + 2] cycloaddition from a jatrophane precursor to the gaditanane skeleton, an unprecedented 5/6/4/6-fused tetracyclic ring framework recently isolated from Euphorbia spp., was studied using the bond reactivity indices approach. Furthermore, six diterpenoids, including three undescribed jatrophanes isolated from E. gaditana Coss, were described. The structures of these compounds were deduced by a combination of 2D NMR spectroscopy and ECD data analysis.

Heterologous expression of plant glycosyltransferases for biochemistry and structural biology.

Much of the carbon captured by photosynthesis is converted into the polysaccharides that constitute plant cell walls. These complex macrostructures are composed of cellulose, hemicellulose, and pectins, together with small amounts of structural proteins, minerals, and in many cases lignin. Wall components assemble and interact with one another to produce dynamic structures with many capabilities, including providing mechanical support to plant structures and determining plant cell shape and size. Despite their abundance, major gaps in our knowledge of the synthesis of the building blocks of these polymers remain, largely due to ineffective methods for expression and purification of active synthetic enzymes for in vitro biochemical analyses. The hemicellulosic polysaccharide, xyloglucan, comprises up to 25% of the dry weight of primary cell walls in plants. Most of the knowledge about the glycosyltransferases (GTs) involved in the xyloglucan biosynthetic pathway has been derived from the identification and carbohydrate analysis of knockout mutants, lending little information on how the catalytic biosynthesis of xyloglucan occurs in planta. In this chapter we describe methods for the heterologous expression of plant GTs using the HEK293 expression platform. As a demonstration of the utility of this platform, nine xyloglucan-relevant GTs from three different CAZy families were evaluated, and methods for expression, purification, and construct optimization are described for biochemical and structural characterization.

Locating Methyl-Etherified and Methyl-Esterified Uronic Acids in the Plant Cell Wall Pectic Polysaccharide Rhamnogalacturonan II.

Rhamnogalacturonan II (RG-II) is a structurally complex pectic polysaccharide that exists as a borate ester cross-linked dimer in the cell walls of all vascular plants. The glycosyl sequence of RG-II is largely conserved, but there is evidence that galacturonic acid (GalA) methyl etherification and glucuronic acid (GlcA) methyl esterification vary in the A sidechain across plant species. Methyl esterification of the galacturonan backbone has also been reported but not confirmed. Here we describe a new procedure, utilizing aq. sodium borodeuteride (NaBD4)-reduced RG-II, to identify the methyl esterification status of backbone GalAs. Our data suggest that up to two different GalAs are esterified in the RG-II backbone. We also adapted a procedure based on methanolysis and NaBD4 reduction to identify 3-, 4-, and 3,4-O-methyl GalA in RG-II. These data, together with matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF) MS analysis of sidechain A generated from selected RG-IIs and their NaBD4-reduced counterparts, suggest that methyl etherification of the ß-linked GalA and methyl esterification of the GlcA are widespread. Nevertheless, the extent of these modifications varies between plant species. Our analysis of the sidechain B glycoforms in RG-II from different dicots and nonpoalean monocots suggests that this sidechain has a minimum structure of an O-acetylated hexasaccharide (Ara-[MeFuc]-Gal-AceA-Rha-Api-). To complement these studies, we provide further evidence showing that dimer formation and stability in vitro is cation and borate dependent. Taken together, our data further refine the primary sequence and sequence variation of RG-II and provide additional insight into dimer stability and factors controlling dimer self-assembly.

Nanocellulose-Based Sustainable Dyeing of Cotton Textiles with Minimized Water Pollution.

This research aims at minimizing environmental pollution by effluents discharged from current textile dyeing processes. The reduction of pollution is approached with a nanofibrillated cellulose (NFC) dyeing method. In the commonly used exhaust reactive dye bath cotton dyeing process, water effluents are contaminated with unreacted dyes and dyeing formulation auxiliaries amid the consumption of 20 weight units of water per weight unit of colored textile products. It was recently demonstrated that using reactive dye-colored NFC hydrogels-an aqueous dispersion of the NFC pigment-a sustainable dye carrier-results in 6-fold reduction in consumption of water and auxiliaries. Here, we report further developments of this technology. Cotton fabrics and NFC hydrogels inherit a fraction of soluble polysugars that react and conjugate with the reactive dyes. These soluble dye-conjugated polysugars are released into the wastewater, thus resulting in water pollution and also in reduced efficiency of the dyeing process. We demonstrate here that post-treatment of NFC-colored cotton textiles with polycarboxylic acid secures permanent chemical grafting of the soluble dye-labeled polysugars and forms chemical cross-links with the NFC fibers on the cotton fabric via the esterification reaction. This combination leads to the improvement of dye fixation by 30% and reduces the dye discharge in the washing stage by 60%. This enhancement is approached without compromising the stiffness and breathability of the fabrics. The advanced textile method is tested for a series of reactive dyes covering the entire visual spectrum range.

Molecular Mechanism of Polysaccharide Acetylation by the Arabidopsis Xylan O-acetyltransferase XOAT1.

Xylans are a major component of plant cell walls. O-Acetyl moieties are the dominant backbone substituents of glucuronoxylan in dicots and play a major role in the polymer-polymer interactions that are crucial for wall architecture and normal plant development. Here, we describe the biochemical, structural, and mechanistic characterization of Arabidopsis (Arabidopsis thaliana) xylan O-acetyltransferase 1 (XOAT1), a member of the plant-specific Trichome Birefringence Like (TBL) family. Detailed characterization of XOAT1-catalyzed reactions by real-time NMR confirms that it exclusively catalyzes the 2-O-acetylation of xylan, followed by nonenzymatic acetyl migration to the O-3 position, resulting in products that are monoacetylated at both O-2 and O-3 positions. In addition, we report the crystal structure of the catalytic domain of XOAT1, which adopts a unique conformation that bears some similarities to the α/ß/α topology of members of the GDSL-like lipase/acylhydrolase family. Finally, we use a combination of biochemical analyses, mutagenesis, and molecular simulations to show that XOAT1 catalyzes xylan acetylation through formation of an acyl-enzyme intermediate, Ac-Ser-216, by a double displacement bi-bi mechanism involving a Ser-His-Asp catalytic triad and unconventionally uses an Arg residue in the formation of an oxyanion hole.

Development of a thermophilic coculture for corn fiber conversion to ethanol.

The fiber in corn kernels, currently unutilized in the corn to ethanol process, represents an opportunity for introduction of cellulose conversion technology. We report here that Clostridium thermocellum can solubilize over 90% of the carbohydrate in autoclaved corn fiber, including its hemicellulose component glucuronoarabinoxylan (GAX). However, Thermoanaerobacterium thermosaccharolyticum or several other described hemicellulose-fermenting thermophilic bacteria can only partially utilize this GAX. We describe the isolation of a previously undescribed organism, Herbinix spp. strain LL1355, from a thermophilic microbiome that can consume 85% of the recalcitrant GAX. We sequence its genome, and based on structural analysis of the GAX, identify six enzymes that hydrolyze GAX linkages. Combinations of up to four enzymes are successfully expressed in T. thermosaccharolyticum. Supplementation with these enzymes allows T. thermosaccharolyticum to consume 78% of the GAX compared to 53% by the parent strain and increases ethanol yield from corn fiber by 24%.

Analytical Techniques for Determining the Role of Domain of Unknown Function 579 Proteins in the Synthesis of O-Methylated Plant Polysaccharides.

Matrix polysaccharides are a diverse group of structurally complex carbohydrates and account for a large portion of the biomass consumed as food or used to produce fuels and materials. Glucuronoxylan and arabinogalactan protein are matrix glycans that have sidechains decorated with 4-O-methyl glucuronosyl residues. Methylation is a key determinant of the physical properties of these wall glycopolymers and consequently affects both their biological function and ability to interact with other wall polymers. Indeed, there is increasing interest in determining the distribution and abundance of methyl-etherified polysaccharides in different plant species, tissues, and developmental stages. There is also a need to understand the mechanisms involved in their biosynthesis. Members of the Domain of Unknown Function (DUF) 579 family have been demonstrated to have a role in the biosynthesis of methyl-etherified glycans. Here we describe methods for the analysis of the 4-O-methyl glucuronic acid moieties that are present in sidechains of arabinogalactan proteins. These methods are then applied toward the analysis of loss-of-function mutants of two DUF579 family members that lack this modification in muro. We also present a procedure to assay DUF579 family members for enzymatic activity in vitro using acceptor oligosaccharides prepared from xylan of loss-of-function mutants. Our approach facilitates the characterization of enzymes that modify glycosyl residues during cell wall synthesis and the structures that they generate.

Biochemical and Genetic Analysis Identify CSLD3 as a beta-1,4-Glucan Synthase That Functions during Plant Cell Wall Synthesis.

In plants, changes in cell size and shape during development fundamentally depend on the ability to synthesize and modify cell wall polysaccharides. The main classes of cell wall polysaccharides produced by terrestrial plants are cellulose, hemicelluloses, and pectins. Members of the cellulose synthase (CESA) and cellulose synthase-like (CSL) families encode glycosyltransferases that synthesize the ß-1,4-linked glycan backbones of cellulose and most hemicellulosic polysaccharides that comprise plant cell walls. Cellulose microfibrils are the major load-bearing component in plant cell walls and are assembled from individual ß-1,4-glucan polymers synthesized by CESA proteins that are organized into multimeric complexes called CESA complexes, in the plant plasma membrane. During distinct modes of polarized cell wall deposition, such as in the tip growth that occurs during the formation of root hairs and pollen tubes or de novo formation of cell plates during plant cytokinesis, newly synthesized cell wall polysaccharides are deposited in a restricted region of the cell. These processes require the activity of members of the CESA-like D subfamily. However, while these CSLD polysaccharide synthases are essential, the nature of the polysaccharides they synthesize has remained elusive. Here, we use a combination of genetic rescue experiments with CSLD-CESA chimeric proteins, in vitro biochemical reconstitution, and supporting computational modeling and simulation, to demonstrate that Arabidopsis (Arabidopsis thaliana) CSLD3 is a UDP-glucose-dependent ß-1,4-glucan synthase that forms protein complexes displaying similar ultrastructural features to those formed by CESA6.

Acute effect of an amino acid mixture in the rat glycemic profile.

Amino acid mixtures (AAM) are protein substitutes used for phenylketonuria treatment, but their metabolic effects have not been well characterized. The objective of this study was to compare the acute glycemic response to free amino acids (free AA) from AAM with the response to intact protein (iProtein). Male Wistar rats (n = 14) were administered by gavage a bolus of free AA (n = 7) or iProtein as albumin (n = 7) containing equivalent amounts of nitrogen. Blood glucose and insulin levels were measured at baseline and 15, 30, 60 and 120 minutes later, when gut GLP-1 content and pancreatic insulin, GLP-1 receptor and Ki67 expression were quantified at 120 minutes time point. After AAM, glucose area under the curve (free AA vs iProtein; P < 0.01), serum insulin levels at 120 minutes (free AA vs iProtein; P < 0.05), colon GLP-1 content (free AA vs iProtein; P < 0.01), pancreatic GLP-1 receptor (free AA vs iProtein; P < 0.01) and insulin expression (free AA vs iProtein; p < 0.01) were significantly lower as compared with iProtein. AAM increased Ki67 expression in pancreatic islets (free AA vs iProtein; P < 0.05). In conclusion, this study demonstrated that acute response to AAM differs from iProtein and is characterized by a lower glucose excursion, along with a decrease in gut GLP-1 and pancreatic GLP-1 receptor and insulin. This data suggests the modulation of glycemia by free AA is mediated by the incretin axis.

Desprendimiento coroideo tardío poscirugía de catarata con facoemulsificación en pacientes glaucomatosos / Late choroidal detachment after cataract surgery with phacoemulsification in glaucoma patients

El desprendimiento coroideo es un factor predisponente y causa de hipotonía ocular marcada. Se describen dos pacientes operados de glaucoma por técnica de trabeculectomía simple, con más de 5 años de evolución, bajo régimen medicamentoso de timolol 0,5 por ciento colirio, 2 veces por día, intervenidos de catarata senil con técnica de facoemulsificación sin complicaciones trans ni posquirúrgicas inmediatas, quienes presentan disminución brusca de la agudeza visual a dos meses de la cirugía, por desprendimiento coroideo sin pérdida de cámara anterior, asociado a hipotonía ocular y maculopatía. Se analizan las posibles causas y se impone tratamiento adecuado. Finalmente se logra una evolución satisfactoria(AU)

Choroidal detachment is a cause of and predisposing factor for marked ocular hypotony. A description is provided of two patients undergoing glaucoma surgery by simple trabeculectomy technique, with more than five years of evolution, under drug treatment with 0.5 percent timolol collyrium twice daily, intervened for senile cataract with phacoemulsification technique, without any intra- or immediate post-operative complications, who presented with sudden visual acuity reduction two months after surgery, due to choroidal detachment without anterior chamber loss, associated to ocular hypotony and maculopathy. The possible causes are analyzed and appropriate treatment is indicated. Satisfactory evolution is finally achieved(AU)

Desprendimiento coroideo tardío poscirugía de catarata con facoemulsificación en pacientes glaucomatosos / Late choroidal detachment after cataract surgery with phacoemulsification in glaucoma patients

El desprendimiento coroideo es un factor predisponente y causa de hipotonía ocular marcada. Se describen dos pacientes operados de glaucoma por técnica de trabeculectomía simple, con más de 5 años de evolución, bajo régimen medicamentoso de timolol 0,5 por ciento colirio, 2 veces por día, intervenidos de catarata senil con técnica de facoemulsificación sin complicaciones trans ni posquirúrgicas inmediatas, quienes presentan disminución brusca de la agudeza visual a dos meses de la cirugía, por desprendimiento coroideo sin pérdida de cámara anterior, asociado a hipotonía ocular y maculopatía. Se analizan las posibles causas y se impone tratamiento adecuado. Finalmente se logra una evolución satisfactoria(AU)

Choroidal detachment is a cause of and predisposing factor for marked ocular hypotony. A description is provided of two patients undergoing glaucoma surgery by simple trabeculectomy technique, with more than five years of evolution, under drug treatment with 0.5 percent timolol collyrium twice daily, intervened for senile cataract with phacoemulsification technique, without any intra- or immediate post-operative complications, who presented with sudden visual acuity reduction two months after surgery, due to choroidal detachment without anterior chamber loss, associated to ocular hypotony and maculopathy. The possible causes are analyzed and appropriate treatment is indicated. Satisfactory evolution is finally achieved(AU)

Características epidemiológicas y clínicas de los lactantes hospitalizados por infecciones por parechovirus humanos. Estudio prospectivo en España / Epidemiological and clinical characteristics of infants admitted to hospital due to human parechovirus infections: A prospective study in Spain

Introducción: Los parechovirus humanos (HPeV) son virus de la familia Picornaviridae, recientemente descritos, a los que se atribuyen cuadros de fiebre sin foco (FSF), sepsis clínica, gastroenteritis, meningitis o encefalitis fundamentalmente en lactantes pequeños. Nuestro objetivo fue describir la epidemiología y las características clínicas de las infecciones por HPeV en nuestro medio. Pacientes y métodos: Estudio multicéntrico prospectivo, llevado a cabo en 12 hospitales a nivel nacional, entre 2013-2015, en niños < 3 años con FSF, sepsis clínica o patología neurológica. Se realizó determinación de HPeV mediante RT-PCR en el Centro Nacional de Microbiología en suero, heces o líquido cefalorraquídeo. Resultados: Se analizan 47 infecciones por HPeV de un total de 850 muestras (5,52%), siendo HPeV-3 el más frecuente (29 casos), con predominio en mayo y julio, con una distribución bienal. El 57% eran neonatos y solo 2 > 3 meses. Todos los pacientes presentaron fiebre, el 45% irritabilidad, el 18,6% exantema y el 14% diarrea. No se observa ninguna alteración específica en las pruebas bioquímicas. El diagnóstico final más frecuente fue FSF (61%) seguido de sepsis clínica (29%). Aunque un 29% de los niños precisaron ingreso en cuidados intensivos, solo un paciente presentó secuelas. Conclusiones: Los HPeV circulan en nuestro país, afectando fundamentalmente a lactantes < 2 meses y se asocian a FSF y sepsis clínica, con un predominio en primavera y verano. Sería de interés implementar las técnicas moleculares de diagnóstico en todos los hospitales para reconocer y manejar adecuadamente estas infecciones (AU)

Introduction: Human parechovirus (HPeV) is one of the recently described picornaviridae viruses that have been associated with fever of unknown origin (FUO), clinical sepsis, gastroenteritis, meningitis, or encephalitis in very young infants. The aim of this study is to describe the epidemiology and clinical features of these viruses. Patients and methods: A prospective multicentre 3-year study was conducted in 12 hospitals in Spain. Out of 850 specimens examined, 47 were positive (5.52%), with HPeV-3 being the most frequent (29 cases). Infections occurred throughout the year, but mainly in May and July, and a biennial distribution was observed. More than half (57%) were neonates, and only 2 children were older than 3 months. Fever was present in all children, with irritability in 45%, rash in 18.6%, and diarrhoea in 14%. The results of biochemical tests were all in normal range. The most common final diagnosis was FUO (61%), followed by clinical sepsis (29%). Up to 29% of infants were admitted to the intensive care unit, but only one patient had sequelae. Results: Out of 850 specimens examined, 47 were positive (5.52%) for HPeV, with HPeV-3 being the most frequent (29 cases). Infections occurred throughout the year, but mainly in May and July, and a biennial distribution was observed. More than half (57%) were neonates, and only 2 children were older than 3 months. Fever was present in all children, with irritability in 45%, rash in 18.6%, and diarrhoea in 14%. The results of biochemical tests were all in normal range. The most common final diagnosis was FUO (61%), followed by clinical sepsis (29%). Up to 29% of infants were admitted to the intensive care unit, but only one patient had sequelae. Conclusions: HPeV circulates in our country, mainly during spring and summer, and affects young infants with a FUO and clinical sepsis. Molecular diagnostic techniques in all hospitals could help in improving the management of patients with these infections (AU)

[Epidemiological and clinical characteristics of infants admitted to hospital due to human parechovirus infections: A prospective study in Spain]. / Características epidemiológicas y clínicas de los lactantes hospitalizados por infecciones por parechovirus humanos. Estudio prospectivo en España.

INTRODUCTION: Human parechovirus (HPeV) is one of the recently described picornaviridae viruses that have been associated with fever of unknown origin (FUO), clinical sepsis, gastroenteritis, meningitis, or encephalitis in very young infants. The aim of this study is to describe the epidemiology and clinical features of these viruses. PATIENTS AND METHODS: A prospective multicentre 3-year study was conducted in 12 hospitals in Spain. Out of 850 specimens examined, 47 were positive (5.52%), with HPeV-3 being the most frequent (29 cases). Infections occurred throughout the year, but mainly in May and July, and a biennial distribution was observed. More than half (57%) were neonates, and only 2 children were older than 3 months. Fever was present in all children, with irritability in 45%, rash in 18.6%, and diarrhoea in 14%. The results of biochemical tests were all in normal range. The most common final diagnosis was FUO (61%), followed by clinical sepsis (29%). Up to 29% of infants were admitted to the intensive care unit, but only one patient had sequelae. RESULTS: Out of 850 specimens examined, 47 were positive (5.52%) for HPeV, with HPeV-3 being the most frequent (29 cases). Infections occurred throughout the year, but mainly in May and July, and a biennial distribution was observed. More than half (57%) were neonates, and only 2 children were older than 3 months. Fever was present in all children, with irritability in 45%, rash in 18.6%, and diarrhoea in 14%. The results of biochemical tests were all in normal range. The most common final diagnosis was FUO (61%), followed by clinical sepsis (29%). Up to 29% of infants were admitted to the intensive care unit, but only one patient had sequelae CONCLUSIONS: HPeV circulates in our country, mainly during spring and summer, and affects young infants with a FUO and clinical sepsis. Molecular diagnostic techniques in all hospitals could help in improving the management of patients with these infections.

Changes in the abundance of cell wall apiogalacturonan and xylogalacturonan and conservation of rhamnogalacturonan II structure during the diversification of the Lemnoideae.

MAIN CONCLUSION: The diversification of the Lemnoideae was accompanied by a reduction in the abundance of cell wall apiogalacturonan and an increase in xylogalacturonan whereas rhamnogalacturonan II structure and cross-linking are conserved. The subfamily Lemnoideae is comprised of five genera and 38 species of small, fast-growing aquatic monocots. Lemna minor and Spirodela polyrhiza belong to this subfamily and have primary cell walls that contain large amounts of apiogalacturonan and thus are distinct from the primary walls of most other flowering plants. However, the pectins in the cell walls of other members of the Lemnoideae have not been investigated. Here, we show that apiogalacturonan decreased substantially as the Lemnoideae diversified since Wolffiella and Wolffia walls contain between 63 and 88% less apiose than Spirodela, Landoltia, and Lemna walls. In Wolffia, the most derived genus, xylogalacturonan is far more abundant than apiogalacturonan, whereas in Wolffiella pectic polysaccharides have a high arabinose content, which may arise from arabinan sidechains of RG I. The apiose-containing pectin rhamnogalacturonan II (RG-II) exists in Lemnoideae walls as a borate cross-linked dimer and has a glycosyl sequence similar to RG-II from terrestrial plants. Nevertheless, species-dependent variations in the extent of methyl-etherification of RG-II sidechain A and arabinosylation of sidechain B are discernible. Immunocytochemical studies revealed that pectin methyl-esterification is higher in developing daughter frond walls than in mother frond walls, indicating that methyl-esterification is associated with expanding cells. Our data support the notion that a functional cell wall requires conservation of RG-II structure and cross-linking but can accommodate structural changes in other pectins. The Lemnoideae provide a model system to study the mechanisms by which wall structure and composition has changed in closely related plants with similar growth habits.