The precise localization of extracellular matrix and cell wall components is of critical importance for multicellular organisms. Lignin is a major cell wall modification that often forms intricate ...subcellular patterns that are central to cellular function. Yet the mechanisms of lignin polymerization and the subcellular precision of its formation remain enigmatic. Here, we show that the Casparian strip, a lignin-based, paracellular diffusion barrier in plants, forms as a precise, median ring by the concerted action of a specific, localized NADPH oxidase, brought into proximity of localized peroxidases through the action of Casparian strip domain proteins (CASPs). Our findings in Arabidopsis provide a simple mechanistic model of how plant cells regulate lignin formation with subcellular precision. We speculate that scaffolding of NADPH oxidases to the downstream targets of the reactive oxygen species (ROS) that they produce might be a widespread mechanism to ensure specificity and subcellular precision of ROS action within the extracellular matrix.
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► A specific NADPH oxidase is crucial for formation of lignified Casparian strips ► NADPH oxidase specificity depends on subcellular localization and regulatory domain ► CASPs recruit secreted peroxidases to the Casparian strip domain ► The assembly of NADPH oxidase and peroxidases drives localized lignin formation
CASP scaffolding proteins recruit a specific NADPH oxidase as well as extracellular peroxidases to sites of Casparian strips, diffusion barriers that form via lignin deposition. The combined action of these enzymes regulates ROS levels to drive local lignin polymerization.
Due to the sluggish kinetics of the hydrogen oxidation reaction (HOR) in alkaline electrolytes, the development of more efficient HOR catalysts is essential for the next generation of anion‐exchange ...membrane fuel cells (AEMFCs). In this work, CeOx is selectively deposited onto carbon‐supported Pd nanoparticles by controlled surface reactions, aiming to enhance the homogenous distribution of CeOx and its preferential attachment to Pd nanoparticles, to achieve highly active CeOx‐Pd/C catalysts. The catalysts are characterized by inductively coupled plasma–atomic emission spectroscopy, X‐ray diffraction, high‐resolution transmission electron microscopy, scanning transmission electron microscopy (STEM), electron energy loss spectroscopy, and X‐ray photoelectron spectroscopy to confirm the bulk composition, phases present, morphology, elemental mapping, local oxidation, and surface chemical states, respectively. The intimate contact between Pd and CeOx is shown through high‐resolution STEM maps. The oxophilic nature of CeOx and its effect on Pd are probed by CO stripping. The interfacial contact area between CeOx and Pd nanoparticles is calculated for the first time and correlated to the electrochemical performance of the CeOx‐Pd/C catalysts. Highest recorded HOR specific exchange current (51.5 mA mg−1Pd) and H2–O2 AEMFC performance (peak power density of 1,169 mW cm−2 mgPd−1) are obtained with a CeOx‐Pd/C catalyst with Ce0.38/Pd bulk atomic ratio.
This contribution presents a novel approach to synthesize highly active CeOx‐Pd/C catalysts by controlled surface reactions for intimate contact between CeOx and Pd nanoparticles. The hydrogen oxidation reaction activity is directly correlated to the interfacial contact area between CeOx and Pd. This catalyst shows the highest HOR activity and a record high in operando anion‐exchange membrane fuel cells performance.
Anthropogenic emissions of CO2 from industrial processes are considered the major cause of global warming and ocean acidification. To this end, different abatement strategies have been sought to ...capture CO2 directly from various effluent sources. Carbon capture and sequestration (CCS) has been touted to solve this problem; however, due to the challenges associated with this approach, research efforts have been focused on the development of dual-function materials (DFMs) that can effectively capture and convert CO2 to value-added products. In this review, we first describe existent CO2 capture processes, followed by relevant CO2 adsorbents. Then, we focus on the development of DFMs for CO2 capture and conversion through various reaction pathways, such as methanation, reverse water-gas shift, and dry reforming. We also elaborate on the challenges associated with these systems with emphasis on the stability and regenerability of the materials. Finally, some future perspectives and possible areas of study are highlighted.
We demonstrated the self-assembly of transition metal carbide nanoparticles coated with atomically thin noble metal monolayers by carburizing mixtures of noble metal salts and transition metal oxides ...encapsulated in removable silica templates. This approach allows for control of the final core-shell architecture, including particle size, monolayer coverage, and heterometallic composition. Carbon-supported Ti0.1W0.9C nanoparticles coated with Pt or bimetallic PtRu monolayers exhibited enhanced resistance to sintering and CO poisoning, achieving an order of magnitude increase in specific activity over commercial catalysts for methanol electrooxidation after 10,000 cycles. These core-shell materials provide a new direction to reduce the loading, enhance the activity, and increase the stability of noble metal catalysts.
The histologic examination of endoscopic biopsies or resection specimens remains a key step in the work-up of affected inflammatory bowel disease (IBD) patients and can be used for diagnosis and ...differential diagnosis, particularly in the differentiation of UC from CD and other non-IBD related colitides. The introduction of new treatment strategies in inflammatory bowel disease (IBD) interfering with the patients' immune system may result in mucosal healing, making the pathologists aware of the impact of treatment upon diagnostic features. The European Crohn's and Colitis Organisation (ECCO) and the European Society of Pathology (ESP) jointly elaborated a consensus to establish standards for histopathology diagnosis in IBD. The consensus endeavors to address: (i) procedures required for a proper diagnosis, (ii) features which can be used for the analysis of endoscopic biopsies, (iii) features which can be used for the analysis of surgical samples, (iv) criteria for diagnosis and differential diagnosis, and (v) special situations including those inherent to therapy. Questions that were addressed include: how many features should be present for a firm diagnosis? What is the role of histology in patient management, including search for dysplasia? Which features if any, can be used for assessment of disease activity? The statements and general recommendations of this consensus are based on the highest level of evidence available, but significant gaps remain in certain areas.
Fertility preservation is an urgent challenge in the transplant setting. A panel of transplanters and fertility specialists within the Pediatric Diseases Working Party of the European Society for ...Blood and Marrow Transplantation (EBMT) and the International BFM Study Group provides specific guidelines. Patients and families should be informed of possible gender- and age-specific cryopreservation strategies that should be tailored according to the underlying disease, clinical condition and previous exposure to chemotherapy. Semen collection should be routinely offered to all postpubertal boys at the diagnosis of any disease requiring therapy that could potentially impair fertility. Testicular tissue collection might be offered to postpubertal boys; nevertheless, its use has been unsuccessful to date. Oocyte collection after hormonal hyperstimulation should be offered to postpubertal girls facing gonadotoxic therapies that could be delayed for the 2 weeks required for the procedure. Ovarian tissue collection could be offered to pre-/post-pubertal girls. Pregnancies have been reported after postpubertal ovarian tissue reimplantation; however, to date, no pregnancy has been reported after the reimplantation of prepubertal ovarian tissue or in vitro maturation of pre-/post-pubertal ovarian tissue. Possible future advances in reproductive medicine could change this scenario. Health authorities should prioritize fertility preservation projects in pediatric transplantation to improve patient care and quality of life.
For many years, it was generally accepted that the vast majority of the colorectal carcinomas (CRCs) evolved from conventional adenomas, via the adenoma-carcinoma sequence. More recently, serrated ...colorectal polyps (hyperplastic polyps, sessile serrated polyps and traditional serrated adenomas (TSAs)) have emerged as an alternative pathway of colorectal carcinogenesis. It has been estimated that about 30% of the CRC progress via the serrated pathway. Recently, TSAs were also detected in the upper digestive tract. In this work, we review the literature on TSA in the oesophagus, the stomach, the duodenum, the pancreatic main duct and the gallbladder. The review indicated that 53.4% (n=39) out of the 73 TSA of the upper digestive tract now in record showed a simultaneously growing invasive carcinoma. As a corollary, TSAs of the upper digestive tract are aggressive adenomas that should be radically excised, either endoscopically or surgically, to rule out the possibility of a synchronously growing invasive adenocarcinoma or to prevent cancer progression. The present findings substantiate a TSA pathway of carcinogenesis in the upper digestive tract.
Abstract
STUDY QUESTION
What is the origin and composition of cell-free DNA in human embryo spent culture media?
SUMMARY ANSWER
Cell-free DNA from human embryo spent culture media represents a mix of ...maternal and embryonic DNA, and the mixture can be more complex for mosaic embryos.
WHAT IS KNOWN ALREADY
In 2016, ~300 000 human embryos were chromosomally and/or genetically analyzed using preimplantation genetic testing for aneuploidies (PGT-A) or monogenic disorders (PGT-M) before transfer into the uterus. While progress in genetic techniques has enabled analysis of the full karyotype in a single cell with high sensitivity and specificity, these approaches still require an embryo biopsy. Thus, non-invasive techniques are sought as an alternative.
STUDY DESIGN, SIZE, DURATION
This study was based on a total of 113 human embryos undergoing trophectoderm biopsy as part of PGT-A analysis. For each embryo, the spent culture media used between Day 3 and Day 5 of development were collected for cell-free DNA analysis. In addition to the 113 spent culture media samples, 28 media drops without embryo contact were cultured in parallel under the same conditions to use as controls. In total, 141 media samples were collected and divided into two groups: one for direct DNA quantification (53 spent culture media and 17 controls), the other for whole-genome amplification (60 spent culture media and 11 controls) and subsequent quantification. Some samples with amplified DNA (N = 56) were used for aneuploidy testing by next-generation sequencing; of those, 35 samples underwent single-nucleotide polymorphism (SNP) sequencing to detect maternal contamination. Finally, from the 35 spent culture media analyzed by SNP sequencing, 12 whole blastocysts were analyzed by fluorescence in situ hybridization (FISH) to determine the level of mosaicism in each embryo, as a possible origin for discordance between sample types.
PARTICIPANTS/MATERIALS, SETTING, METHODS
Trophectoderm biopsies and culture media samples (20 μl) underwent whole-genome amplification, then libraries were generated and sequenced for an aneuploidy study. For SNP sequencing, triads including trophectoderm DNA, cell-free DNA, and follicular fluid DNA were analyzed. In total, 124 SNPs were included with 90 SNPs distributed among all autosomes and 34 SNPs located on chromosome Y. Finally, 12 whole blastocysts were fixed and individual cells were analyzed by FISH using telomeric/centromeric probes for the affected chromosomes.
MAIN RESULTS AND THE ROLE OF CHANCE
We found a higher quantity of cell-free DNA in spent culture media co-cultured with embryos versus control media samples (P ≤ 0.001). The presence of cell-free DNA in the spent culture media enabled a chromosomal diagnosis, although results differed from those of trophectoderm biopsy analysis in most cases (67%). Discordant results were mainly attributable to a high percentage of maternal DNA in the spent culture media, with a median percentage of embryonic DNA estimated at 8%. Finally, from the discordant cases, 91.7% of whole blastocysts analyzed by FISH were mosaic and 75% of the analyzed chromosomes were concordant with the trophectoderm DNA diagnosis instead of the cell-free DNA result.
LIMITATIONS, REASONS FOR CAUTION
This study was limited by the sample size and the number of cells analyzed by FISH.
WIDER IMPLICATIONS OF THE FINDINGS
This is the first study to combine chromosomal analysis of cell-free DNA, SNP sequencing to identify maternal contamination, and whole-blastocyst analysis for detecting mosaicism. Our results provide a better understanding of the origin of cell-free DNA in spent culture media, offering an important step toward developing future non-invasive karyotyping that must rely on the specific identification of DNA released from human embryos.
STUDY FUNDING/ COMPETING INTEREST
This work was funded by Igenomix S.L. There are no competing interests.
One of the most significant challenges in the use of heterogeneous catalysts is the loss of activity and/or selectivity with time on stream, and researchers have explored different methods to ...overcome this problem. Recently, the coating of catalysts to control their deactivation has generated much research traction. This Review is aimed at studying different encapsulation techniques employed for controlling catalyst deactivation. Focus is given to the prevention of irreversible modes of deactivation, such as sintering and leaching. In this Review, we elaborate on different entrapment methods used to protect catalysts from deactivation in both liquid and gas reaction media. Relevant probe reactions are discussed with emphasis on the catalyst activity and stability. Challenges associated with those processes are also described with emphasis on the mass transfer limitations as a result of the coverage of the active sites. Finally, some future perspectives and areas for possible improvement are highlighted.
The use of fiber-reinforced composites in marine applications such as components of tidal turbines and wave energy converters is becoming attractive because of their reduced weight and improved ...corrosion resistance. However, when these polymer matrix composite structures are exposed to seawater environment, degradation of material properties is produced affecting reliability. A deep understating of seawater ageing effect on composite structures is essential to ensure long-term performance and durability. A systematic investigation was conducted in this work to evaluate the effect of seawater ageing on mechanical properties of five different composites manufactured with two types of fiber fabrics (unidirectional glass and carbon) and three types of resin systems (epoxy, vinylester and polyester). The behavior of samples with and without accelerated seawater ageing and subjected to tensile, compressive, flexural and shear loading was evaluated. A significant strength reduction due to seawater ageing was observed on composites with epoxy and polyester matrices. Low strength and stiffness values of composites with vinylester matrix are in general observed; however, seawater ageing makes these properties increase slightly. Fracture surface examination by scanning electron microscopy revealed delamination, fiber debonding and resin crumbling due to seawater effect.
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