Direct Electron Transfer-Type Oxidoreductases for Biomedical Applications.

Among the various types of enzyme-based biosensors, sensors utilizing enzymes capable of direct electron transfer (DET) are recognized as the most ideal. However, only a limited number of redox enzymes are capable of DET with electrodes, that is, dehydrogenases harboring a subunit or domain that functions specifically to accept electrons from the redox cofactor of the catalytic site and transfer the electrons to the external electron acceptor. Such subunits or domains act as built-in mediators for electron transfer between enzymes and electrodes; consequently, such enzymes enable direct electron transfer to electrodes and are designated as DET-type enzymes. DET-type enzymes fall into several categories, including redox cofactors of catalytic reactions, built-in mediators for DET with electrodes and by their protein hierarchic structures, DET-type oxidoreductases with oligomeric structures harboring electron transfer subunits, and monomeric DET-type oxidoreductases harboring electron transfer domains. In this review, we cover the science of DET-type oxidoreductases and their biomedical applications. First, we introduce the structural biology and current understanding of DET-type enzyme reactions. Next, we describe recent technological developments based on DET-type enzymes for biomedical applications, such as biosensors and biochemical energy harvesting for self-powered medical devices. Finally, after discussing how to further engineer and create DET-type enzymes, we address the future prospects for DET-type enzymes in biomedical engineering.

Stem integrity in Arabidopsis thaliana requires a load-bearing epidermis.

Because plant cells are glued to each other via their cell walls, failure to coordinate growth among adjacent cells can create cracks in tissues. Here, we find that the unbalanced growth of inner and outer tissues in the clavata3 de-etiolated3 (clv3 det3) mutant of Arabidopsis thaliana stretched epidermal cells, ultimately generating cracks in stems. Stem growth slowed before cracks appeared along clv3 det3 stems, whereas inner pith cells became drastically distorted and accelerated their growth, yielding to stress, after the appearance of cracks. This is consistent with a key role of the epidermis in restricting growth. Mechanical property measurements recorded using an atomic force microscope revealed that epidermal cell wall stiffness decreased in det3 and clv3 det3 epidermises. Thus, we hypothesized that stem integrity depends on the epidermal resistance to mechanical stress. To formally test this hypothesis, we used the DET3 gene as part of a tissue-specific strategy to complement cell expansion defects. Epidermis-driven DET3 expression restored growth and restored the frequency of stem cracking to 20% of the clv3 det3 mutant, demonstrating the DET3-dependent load-bearing role of the epidermis.

Molecular mechanism of brassinosteroids involved in root gravity response based on transcriptome analysis.

BACKGROUND: Brassinosteroids (BRs) are a class of phytohormones that regulate a wide range of developmental processes in plants. BR-associated mutants display impaired growth and response to developmental and environmental stimuli. RESULTS: Here, we found that a BR-deficient mutant det2-1 displayed abnormal root gravitropic growth in Arabidopsis, which was not present in other BR mutants. To further elucidate the role of DET2 in gravity, we performed transcriptome sequencing and analysis of det2-1 and bri1-116, bri1 null mutant allele. Expression levels of auxin, gibberellin, cytokinin, and other related genes in the two mutants of det2-1 and bri1-116 were basically the same. However, we only found that a large number of JAZ (JASMONATE ZIM-domain) genes and jasmonate synthesis-related genes were upregulated in det2-1 mutant, suggesting increased levels of endogenous JA. CONCLUSIONS: Our results also suggested that DET2 not only plays a role in BR synthesis but may also be involved in JA regulation. Our study provides a new insight into the molecular mechanism of BRs on the root gravitropism.

Trade-off between double cleavage-stage embryos transfer and single blastocyst-stage embryo transfer in patients with few good quality embryos in antagonist cycles: a retrospective study using a propensity score matching analysis.

OBJECTIVE: This study aimed to compare the per OPU clinical outcomes for transfer of Day 3 double cleavage-stage embryos (DET) and Day 5 single blastocyst-stage (SBT) in patients with five or fewer good quality embryos on day 3 per occyte pick-up cycle (OPU) in antagonist cycles with consideration of blastocyst formation failure. METHODS: This was a retrospective, observational cohort study of 2,116 cases of OPU treated with antagonist protocol in the affiliated Chenggong Hospital of Xiamen University between January 2013 and December 2020. DET was performed in 1,811cycles and SBT was performed in 305 cycles. The DET group was matched to the SBT group by propensity score (PS) matching according to multiple maternal baseline covariates. After PS matching, there were 303 ET cycles in each group. The primary outcomes were the cumulative live birth rate (CLBR), cumulative multiple pregnancy rate(CMPR)per OPU and the number of ET to achieve live birth per OPU. Secondary outcomes were the percentage of clinical pregnancy(CPR), live birth rate(LBR), multiple pregnancy rate(MPR). RESULTS: Following PS mating, the CLBR was slightly higher (48.8% versus 40.3% ; P = 0.041) and the CMPR was significantly higher in the DET group compared to SBT group(44.2% versus 7.9%, P < 0.001). The CPR, LBR and MPR per fresh transfer were higher in DET group compared to SBT group(50.2% versus 28.7%; 41.3% versus 21.5%;29.6% versus 0%, P < 0.001). The number of ET to achieve live birth per OPU in SBT group was obiviously more than in DET group(1.48 ± 0.578 versus 1.22 ± 0.557 ,P < 0.001). CONCLUSION: With a marginal difference cumulative live birth rate, the lower live birth rate per fresh transfer and higher number of ET per OPU in the SBT group suggested that it might take longer time to achieve a live birth with single blastocyst strategy. A trade-off decision should be made between efficiency and safety.

DNA Methylation Analysis of Growth Differences between Upright and Inverted Cuttings of Populus yunnanensis.

DNA methylation is an important mechanism for epigenetic modifications that have been shown to be associated with responses to plant development. Previous studies found that inverted Populus yunnanensis cuttings were still viable and could develop into complete plants. However, the growth status of inverted cuttings was weaker than that of upright cuttings, and the sprouting time of inverted cuttings was later than that of upright cuttings. There is currently no research on DNA methylation patterns in inverted cuttings of Populus yunnanensis. In this study, we detected genome-wide methylation patterns of stem tips of Populus yunnanensis at the early growth stage and the rapid growth stage by Oxford Nanopore Technologies (ONT) methylation sequencing. We found that the methylation levels of CpG, CHG, CHH, and 6mA were 41.34%, 33.79%, 17.27%, and 12.90%, respectively, in the genome of inverted poplar cuttings, while the methylation levels of the four methylation types were higher in the genome of upright poplar cuttings than in inverted cuttings, 41.90%, 34.57%, 18.09%, and 14.11%, suggesting important roles for DNA methylation in poplar cells. In all comparison groups, CpG-type methylation genes in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway were annotated to pathways associated with carbon metabolism, ribosome biogenesis in eukaryotes, glycolysis/gluconeogenesis, pyruvate metabolism, and mRNA detection pathways, suggesting that different biological processes are activated in upright and inverted cuttings. The results show that methylation genes are commonly present in the poplar genome, but only a few of them are involved in the regulation of expression in the growth and development of inverted cuttings. From this, we screened the DET2 gene for significant differences in methylation levels in upright or inverted cuttings. The DET2 gene is a key gene in the Brassinolide (BRs) synthesis pathway, and BRs have an important influence on the growth and development process of plants. These results provide important clues for studying DNA methylation patterns in P. yunnanensis.

Superwettable surfaces and factors impacting microbial adherence in microbiologically-influenced corrosion: a review.

Microbiologically-influenced corrosion (MIC) is a common operational hazard to many industrial processes. The focus of this review lies on microbial corrosion in the maritime industry. Microbial metal attachment and colonization are the critical steps in MIC initiation. We have outlined the crucial factors influencing corrosion caused by microorganism sulfate-reducing bacteria (SRB), where its adherence on the metal surface leads to Direct Electron Transfer (DET)-MIC. This review thus aims to summarize the recent progress and the lacunae in mitigation of MIC. We further highlight the susceptibility of stainless steel grades to SRB pitting corrosion and have included recent developments in understanding the quorum sensing mechanisms in SRB, which governs the proliferation process of the microbial community. There is a paucity of literature on the utilization of anti-quorum sensing molecules against SRB, indicating that the area of study is in its nascent stage of development. Furthermore, microbial adherence to metal is significantly impacted by surface chemistry and topography. Thus, we have reviewed the application of super wettable surfaces such as superhydrophobic, superhydrophilic, and slippery liquid-infused porous surfaces as "anti-corrosion coatings" in preventing adhesion of SRB, providing a potential avenue for the development of practical and feasible solutions in the prevention of MIC. The emerging field of super wettable surfaces holds significant potential for advancing efficient and practical MIC prevention techniques.

Novel insight into ammonium, phosphate, and iron(II) dynamics in the sediment porewater of a constructed wetland under artificial aeration through the diffusive equilibrium in thin films technique.

The analysis of porewater concentrations in constructed wetland sediments could help to understand biogeochemical processes, the sources and sinks of nutrients, and their effect on overlying water quality. In this study, we measured high-resolution porewater concentration profiles of ammonium (NH4+-N), nitrate (NO3N), phosphate (PO43--P), and ferrous iron (Fe(II)) in-situ in the Laratinga constructed wetland in Mount Barker (South Australia) using diffusive equilibration in thin films (DET) techniques. Measurements were taken under light and dark conditions, and non-aerated and aerated conditions to determine the effect on sediment porewater nutrient concentrations. Baseline surface water nutrient concentrations (NH4+-N > 36 mg L-1, PO43--P > 0.43 mg L-1) greatly exceeded water quality guideline criteria. Aeration of the water column alleviated night-time hypoxic conditions (i.e. dissolved oxygen increased from a minimum of 0.7 mg L-1 to a minimum of 4 mg L-1), and increased the redox potential in the sediment. Significant differences were present for NH4+-N, PO43--P, and Fe(II) concentrations with depth in the sediment. Ammonium concentrations in the sediment reduced under aerated conditions, presumably due to enhanced nitrification. However it was observed that PO43--P and Fe(II) concentrations increased significantly with aeration, especially under dark conditions, and were strongly correlated (R2>0.8). This was not what was hypothesised and points to complex interactions between Fe and P in the sediment. Nitrate concentrations in the sediment were below the detection limit (<0.9 mg L-1) which suggests limited nitrification-denitrification is occurring. Overall the results suggest that DET techniques are useful tools for quantifying porewater concentrations of nutrients in constructed wetlands under various environmental conditions.

Electrochemical Characteristics of Shewanella loihica PV-4 on Reticulated Vitreous Carbon (RVC) with Different Potentials Applied.

The current output of an anodic bioelectrochemical system (BES) depends upon the extracellular electron transfer (EET) rate from electricigens to the electrodes. Thus, investigation of EET mechanisms between electricigens and solid electrodes is essential. Here, reticulated vitreous carbon (RVC) electrodes are used to increase the surface available for biofilm formation of the known electricigen Shewanella loihica PV-4, which is limited in conventional flat electrodes. S. loihica PV-4 utilizes flavin-mediated EET at potential lower than the outer membrane cytochromes (OMC), while at higher potential, both direct electron transfer (DET) and mediated electron transfer (MET) contribute to the current output. Results show that high electrode potential favors cell attachment on RVC, which enhances the current output. DET is the prevailing mechanism in early biofilm, while the contribution of MET to current output increased as the biofilm matured. Electrochemical analysis under starvation shows that the mediators could be confined in the biofilm. The morphology of biofilm shows bacteria distributed on the top layer of honeycomb structures, preferentially on the flat areas. This study provides insights into the EET pathways of S. loihica PV-4 on porous RVC electrodes at different biofilm ages and different set potential, which is important for the design of real-world BES.

The origin of SPA reveals the divergence and convergence of light signaling in Archaeplastida.

Plants have evolved various photoreceptors to adapt to changing light environments, and photoreceptors can inactivate the large CONSTITUTIVE PHOTOMORPHOGENIC/DE-ETIOLATED/FUSCA (COP/DET/FUS) protein complex to release their repression of photoresponsive transcription factors. Here, we tracked the origin and evolution of COP/DET/FUS in Archaeplastida and found that most components of COP/DET/FUS were highly conserved. Intriguingly, the COP1-SUPPRESSOR OF PHYA-105 (SPA) protein originated in Chlorophyta but subsequently underwent a distinct evolutionary history in Viridiplantae. SPA experienced duplication events in the ancestors of specific clades after the colonization of land by plants and was divided into two clades (clades A and B) within euphyllophytes (ferns and seed plants). Our phylogenetic and experimental evidences support a new evolutionary model to clarify the divergence and convergence of light signaling during plant evolution.

Which subject-related variables contribute to movement variability during a simulated repetitive and standardised occupational task? Recurrence quantification analysis of surface electromyographic signals.

Movement variability is a component of human movement. This study applied recurrence quantification analysis (RQA) on electromyographic signals to determine the effects of two types of variables on movement variability during a short, simulated repetitive and standardised occupational clip-fitting task. The electrical activity of six muscles in the dominant upper limb was recorded in 21 participants. Variables related to the task performance (insertion force and movements performed when fitting clips) affected RQA measures: recurrence rate (RR), percentage of determinism (DET) and diagonal line length entropy (ENT). Variables related to participant's characteristics (sex, age, and BMI) affected only DET and ENT. A constrasting variability was observed such as a high-DET value combined with a high-ENT value and inversely. Variables affected mainly the recurrences organisation of the more distal muscles. Even if movement variability is complex, it should be considered by ergonomists and work place designers to better understanding of operators' movements. Practitioner summary: It is essential to consider the complexity of operators' movement variability to understand their activities. Based on intrinsic movement variability knowledge, ergonomists and work place designers will be able to modulate the movement variability by acting on workstation designs and occupational organisation with the aim of preserving operators' health. Abbreviations: RR: recurrence rate; DET: percentage of determinism; ENT: diagonal line length entropy; BMI: body mass index; FDS: flexor digitorum superficialis; EXT: extensor digitorum communis; BIC: biceps brachii; TRI: triceps brachii; DEL: deltoideus anterior; TRA: trapezius pars descendens; F: female; M: male; S: supinated; P: pronated; CM: continuous movement; DM: discontinuous movement.

In situ, high-resolution measurement of labile phosphate in sediment porewater using the DET technique coupled with optimized imaging densitometry.

Obtaining two-dimensional distributions of reactive phosphorus in sediment porewater is very important for understanding fine-scale phosphorus mobilization and sequestration processes in sediments. In this study, the diffusive equilibrium in thin films (DET) measurement based on computer imaging densitometry (CID) was studied in detail with optimal conditions described. This study focuses on evaluating the two-dimensional colorimetric DET method coupled with CID (DET-CID method) for porewater labile phosphate measurements. The result shows that the red channel filter is the optimum channel for sensitivity to process the image. Additionally, staining time and temperature have great influence on the method, and 20 min staining time and ≥25 °C staining temperature were recommended. The minimum detection limit of labile phosphate of this method was 0.300 mg P/L, and the maximum detection limit could reach 50.00 mg P/L. The DET-CID technique can be used to measure labile phosphate in a wide range of acidic and alkaline water bodies (pH = 2-10 and water hardness from 0 to 2000 mg/L as CaCO3). The linear regression analysis shows that this technique presents very similar results compared with other two existing methods (R2 = 0.999). Our results would give insights into the precisely measurements of labile phosphate in field applications.

Enzyme-Based Biosensors: Tackling Electron Transfer Issues.

This review summarizes the fundamentals of the phenomenon of electron transfer (ET) reactions occurring in redox enzymes that were widely employed for the development of electroanalytical devices, like biosensors, and enzymatic fuel cells (EFCs). A brief introduction on the ET observed in proteins/enzymes and its paradigms (e.g., classification of ET mechanisms, maximal distance at which is observed direct electron transfer, etc.) are given. Moreover, the theoretical aspects related to direct electron transfer (DET) are resumed as a guideline for newcomers to the field. Snapshots on the ET theory formulated by Rudolph A. Marcus and on the mathematical model used to calculate the ET rate constant formulated by Laviron are provided. Particular attention is devoted to the case of glucose oxidase (GOx) that has been erroneously classified as an enzyme able to transfer electrons directly. Thereafter, all tools available to investigate ET issues are reported addressing the discussions toward the development of new methodology to tackle ET issues. In conclusion, the trends toward upcoming practical applications are suggested as well as some directions in fundamental studies of bioelectrochemistry.

Deoxyelephantopin suppresses hepatic stellate cells activation associated with inhibition of aerobic glycolysis via hedgehog pathway.

Accumulating evidence suggests that hepatic stellate cells (HSCs) adopt aerobic glycolysis during activation. Hedgehog (Hh) pathway plays a vital role in the process of HSCs activation by regulating metabolism, and activation of the Hh pathway promotes transdifferentiation of HSCs into myofibroblasts. Deoxyelephantopin (DET), a naturally occurring sesquiterpene lactone from Elephantopus scaber, has been shown to exert hepatoprotective as well as anticancer effects. However, the effect of DET on hepatic fibrosis and glycolysis in HSCs have never been elucidated. Here, we studied the function of the DET on HSCs activation and investigated the anti-fibrogenic effects of DET was associated with interfering with glycolysis in HSCs. Our results first demonstrated that DET reduced the expression of a-smooth muscle actin (a-SMA) and a1(I)procollagen at both mRNA and protein levels, and restore lipogenesis in HSCs. Furthermore, DET decreased the expression of hexokinase (HK), phosphofructokinase-2 (PFK2), Glucose transporter 4 (Glut4), and reduced lactate production dose-dependently in HSCs. Moreover, we further revealed that DET reduced fibrotic gene expression, restored lipid accumulation in HSCs. However, the Hh pathway agonist SAG could reverse the above effect of DET. Together, these results indicate DET inhibits aerobic glycolysis in HSCs associated with inhibition of Hh pathway. Our results provided a novel mechanism for DET suppression of HSC activation implicated in antifibrotic therapy.

A tomato B-box protein SlBBX20 modulates carotenoid biosynthesis by directly activating PHYTOENE SYNTHASE 1, and is targeted for 26S proteasome-mediated degradation.

Carotenoids play important roles in many biological processes, such as light harvesting, photoprotection and visual attraction in plants. However, the regulation of carotenoid biosynthesis is still not fully understood. Here, we demonstrate that SlBBX20, a B-box (BBX) zinc-finger transcription factor, is a positive regulator of carotenoid accumulation in tomato (Solanum lycopersicum). Overexpression of SlBBX20 leads to dark green fruits and leaves and higher levels of carotenoids relative to the wild-type. Interactions between SlBBX20 and DE-ETIOLATED 1 (SlDET1) lead to the ubiquitination and 26S proteasome-mediated degradation of SlBBX20. Moreover, deficiencies in the components of the CUL4-DDB1-DET1 complex enhanced the stability of the SlBBX20 protein. Thus, we conclude that SlBBX20 is a substrate of the CUL4-DDB1-DET1 E3 ligase. SlBBX20 can activate the expression of PHYTOENE SYNTHASE 1, encoding a key enzyme in carotenoid biosynthesis, by directly binding to a G-box motif in its promoter, which results in the elevated levels of carotenoids in SlBBX20 overexpression lines. We identified a key regulator of carotenoid biosynthesis and demonstrated that the stability of SlBBX20 is regulated by ubiquitination. These findings provide us a new target for the genetic improvement of the nutritional quality of tomato fruit.

Construction and validation of a prediction model to minimize twin rates at preserved high live birth rates after IVF.

RESEARCH QUESTION: Elective single-embryo transfer (eSET) at blastocyst stage is widely used to reduce the frequency of multiple pregnancies after IVF. There are, however, concerns about increased risks for the offspring with prolonged embryo culture. Is it possible to select embryos for transfer at the early cleavage stage and still achieve low twin rates at preserved high live birth rates? DESIGN: A prediction model (PM) was developed to optimize eSET based on variables known 2 days after oocyte retrieval (fresh day 2 embryo transfers; double-embryo transfers 1999-2002 (n=2846) and SET 1999-2003 (n=945); n total=3791). Seventy-five variables were analysed for association with pregnancy chance and twin risk and combined for PM construction. This PM was validated in 2004-2016 including frozen-thawed transfers (FET), to compare cumulative live birth rate (CLBR) and twin rate before (1999-2002 fresh embryo transfers plus FET from the same oocyte retrievals until the end of 2007, n=3495) and after (2004-2011 fresh embryo transfers plus FET from the same oocyte retrievals until the end of 2016, n=11195) implementing the model. RESULTS: The PM was constructed from four independent variables: female age, embryo score, ovarian sensitivity and treatment history. The calibration, i.e. the fit of observed versus predicted results, was excellent both at construction and at validation. Without compromising CLBR, twin rate was reduced from 25.2% to 3.8%, accompanied by profound improvements in perinatal outcome. CONCLUSION: The results provide the first successful construction, validation and impact analysis of a day 2 transfer PM to reduce multiple pregnancies.

The influence of the shape of Au nanoparticles on the catalytic current of fructose dehydrogenase.

Graphite electrodes were modified with triangular (AuNTrs) or spherical (AuNPs) nanoparticles and further modified with fructose dehydrogenase (FDH). The present study reports the effect of the shape of these nanoparticles (NPs) on the catalytic current of immobilized FDH pointing out the different contributions on the mass transfer-limited and kinetically limited currents. The influence of the shape of the NPs on the mass transfer-limited and the kinetically limited current has been proved by using two different methods: a rotating disk electrode (RDE) and an electrode mounted in a wall jet flow-through electrochemical cell attached to a flow system. The advantages of using the wall jet flow system compared with the RDE system for kinetic investigations are as follows: no need to account for substrate consumption, especially in the case of desorption of enzyme, and studies of product-inhibited enzymes. The comparison reveals that virtually identical results can be obtained using either of the two techniques. The heterogeneous electron transfer (ET) rate constants (kS) were found to be 3.8 ± 0.3 s-1 and 0.9 ± 0.1 s-1, for triangular and spherical NPs, respectively. The improvement observed for the electrode modified with AuNTrs suggests a more effective enzyme-NP interaction, which can allocate a higher number of enzyme molecules on the electrode surface. Graphical abstract The shape of gold nanoparticles has a crucial effect on the catalytic current related to the oxidation of D-(-)-fructose to 5-keto-D-(-)-fructose occurring at the FDH-modified electrode surface. In particular, AuNTrs have a higher effect compared with the spherical one.

Influence of human embryo cultivation in a classic CO2 incubator with 20% oxygen versus benchtop incubator with 5% oxygen on live births: the randomized prospective trial.

SummaryOur objective was to assess the effect of benchtop incubators with low oxygen concentrations on the clinical and embryological parameters of our patients. We conducted a prospective, randomized, opened controlled trial on infertile patients in stimulated cycles. In total, 738 infertile patients were assessed for eligibility and, after final exclusions, 230 patients were allocated either to a 5% O2 group (benchtop incubator) or a 20% O2 group (classic incubator). Finally, 198 patients in the 5% O2 group and 195 in the 20% O2 group were analysed. The outcomes measured were fertilization rate, clinical pregnancy rate, and live birth rate. The primary outcome - live birth rate per all transfers - did not show any improvement in the 5% oxygen group over the 20% oxygen group (25.3% versus 22.6%, P=0.531), but the number of day 5 blastocysts was significantly higher (P=0.009). Fertilization rate did not show any beneficial effect of reduced oxygen (5%) (73.4%±22.4% versus 74.6%±24.0%, P=0.606) per all transfers but there was statistically significant difference in the day 5 SET subgroup (85.3±15.1 versus 75.1±17.5; P=0.004). Clinical pregnancy rate showed results in favour of the 5% oxygen group for all subgroups (day 3: 23.7% versus 21.1%, P=0.701; day 5 SET: 35.0% versus 30.6%. P=0.569) but showed statistical significance only in the day 5 SET subgroup (51.1% versus 29.8%; P=0.038). Culturing of embryos in benchtop incubators under low oxygen produced more blastocysts and therefore was a better alternative for embryo selection, which resulted in higher pregnancy rates. To achieve higher live birth rates, embryo quality is not the only factor.

Phosphorus availability and dynamics in soil affected by long-term ruzigrass cover crop.

The use of grasses as cover crops in the off-season of cash crops under no-till has been largely adopted. However, soil phosphorus (P) uptake was previously shown to be reduced when ruzigrass is introduced in the rotation, affecting the viability and sustainability of this cropping system. The objective of this study was to assess the effect of ruzigrass on soil P availability and desorption kinetics under different P fertilizer application rates. A long-term field experiment where soybean (Glycine max) has been grown in rotation with ruzigrass (Urochloa ruziziensis) or fallow for 10 years, with the application of 0, 13, and 26 kg ha-1 of P, was evaluated for two consecutive years. Soil P desorption kinetics was assessed using diffusive equilibrium (DET) and gradient in thin films (DGT) techniques, as well as the DGT-induced fluxes in soils model (DIFS). Microbial biomass P (MBP) was assessed to verify if soil solution P (PDET) was reduced due to immobilization by microorganisms. Ruzigrass reduced MBP and PDET especially when P fertilizer was applied. The concentration of labile P (PDGT) was also lower after ruzigrass than in fallow. The soil ability to resupply P to soil solution was lower after ruzigrass regardless of P rates due to a slower desorption in response to the perturbation imposed by DGT. Growing ruzigrass as cover crop in the soybean off-season decreases soil P availability regardless of P fertilizer application rates by fundamentally reducing P mobility and P resupply from soil solid phase into soil solution.

Timing of Direct Enteral Tube Placement and Outcomes after Acute Stroke.

BACKGROUND: Direct enteral feeding tube (DET) placement for dysphagia after stroke is associated with poor outcomes. However, the relationship between timing of DET placement and poststroke mortality and disability is unknown. We sought to determine the risk of mortality and severe disability in patients who receive DET at different times after stroke. METHODS: We used the Ontario Stroke Registry and linked administrative databases to identify patients with acute ischemic stroke or intracerebral hemorrhage between 2003 and 2013 who received DET (gastrostomy or jejunostomy) during their hospital admission. We grouped patients by week of DET placement and evaluated mortality at 30 days and 6 months after DET insertion, and disability at discharge. We used Cox proportional hazard models and multiple logistic regression to determine the association between time from admission to DET placement and outcomes, adjusting for patient and hospital factors. RESULTS: In the study sample of 1367 patients, the median time from admission to DET placement was 17 days. After adjustment, each week of delay to DET placement was associated with lower mortality at 30 days (adjusted hazard ratio [aHR] .88, 95% confidence interval [CI] .79-.98), but not at 6 months (aHR .98, 95% CI .91- 1.05), and a higher likelihood of severe disability at discharge (adjusted odds ratio 1.35, 95% CI 1.13- 1.60). CONCLUSIONS: Later DET placement after stroke was associated with lower 30-day mortality but higher severe disability at discharge. Further research is needed to understand the reasons for these observations and to optimize patient selection and timing of DET.

Role of Arabidopsis ABF1/3/4 during det1 germination in salt and osmotic stress conditions.

KEY MESSAGE: Arabidopsis det1 mutants exhibit salt and osmotic stress resistant germination. This phenotype requires HY5, ABF1, ABF3, and ABF4. While DE-ETIOLATED 1 (DET1) is well known as a negative regulator of light development, here we describe how det1 mutants also exhibit altered responses to salt and osmotic stress, specifically salt and mannitol resistant germination. LONG HYPOCOTYL 5 (HY5) positively regulates both light and abscisic acid (ABA) signalling. We found that hy5 suppressed the det1 salt and mannitol resistant germination phenotype, thus, det1 stress resistant germination requires HY5. We then queried publically available microarray datasets to identify genes downstream of HY5 that were differentially expressed in det1 mutants. Our analysis revealed that ABA regulated genes, including ABA RESPONSIVE ELEMENT BINDING FACTOR 3 (ABF3), are downregulated in det1 seedlings. We found that ABF3 is induced by salt in wildtype seeds, while homologues ABF4 and ABF1 are repressed, and all three genes are underexpressed in det1 seeds. We then investigated the role of ABF3, ABF4, and ABF1 in det1 phenotypes. Double mutant analysis showed that abf3, abf4, and abf1 all suppress the det1 salt/osmotic stress resistant germination phenotype. In addition, abf1 suppressed det1 rapid water loss and open stomata phenotypes. Thus interactions between ABF genes contribute to det1 salt/osmotic stress response phenotypes.