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One of the largest contributions to biologically available nitrogen comes from the reduction of [N.sub.2] to ammonia by rhizobia in symbiosis with legumes. Plants supply dicarboxylic acids as a carbon source to bacteroids, and in return they receive ammonia. However, metabolic exchange must be more complex, because effective [N.sub.2] fixation by Rhizobium leguminosarum bv viciae bacteroids requires either one of two broad-specificity amino acid ABC transporters (Aap and Bra). It was proposed that amino acids cycle between plant and bacteroids, but the model was unconstrained because of the broad solute specificity of Aap and Bra. Here, we constrain the specificity of Bra and ectopically express heterologous transporters to demonstrate that branched-chain amino acid (LIV) transport is essential for effective [N.sub.2] fixation. This dependence of bacteroids on the plant for LIV is not due to their known down-regulation of glutamate synthesis, because ectopic expression of glutamate dehydrogenase did not rescue effective [N.sub.2] fixation. Instead, the effect is specific to LIV and is accompanied by a major reduction in transcription and activity of LIV biosynthetic enzymes. Bacteroids become symbiotic auxotrophs for LIV and depend on the plant for their supply. Bacteroids with aap bra null mutations are reduced in number, smaller, and have a lower DNA content than wild type. Plants control LIV supply to bacteroids, regulating their development and persistence. This makes it a critical control point for regulation of symbiosis. mutualism | nitrogen fixation | peas | symbiosis

Objectives: To define variables associated with perceived risk of developing rheumatoid arthritis (RA) in first-degree relatives (FDRs) of patients with RA., Methods: Patients with RA and their FDRs were invited to complete cross-sectional surveys. FDR and index patient responses were linked. FDRs' perceived absolute risk, comparative risk, experiential risk and worry about risk were assessed using 5-point Likert scales. FDR predictor variables included demographics, illness perceptions and psychosocial variables. Patient predictors of FDR perceived risk were assessed. Binary logistic regression examined the relationship between FDR characteristics and perceived risk of RA. Generalised estimating equations assessed whether patient variables predicted FDR's perceived risk., Results: 396 FDRs returned a survey. 395 FDRs provided sufficient data and were included in analysis. Paired data from 213 patients were available for 291 of these FDRs. All measures of perceived risk were inter-correlated. 65.2% of FDRs perceived themselves to be 'likely' or 'very likely' to develop RA in their lifetime. Relationship with index patient, high health anxiety, female gender, long perceived RA duration, high perceived concern about RA, negative perceived emotional impact of RA and low perceptions of how well treatment would control RA were all associated with increased FDRs' perceived risk. Patient characteristics did not associate with FDRs' risk perceptions., Conclusions: FDRs' perceived risk of RA was high. Key predictors included being a child of a patient with RA, higher health anxiety and lower perceptions of RA treatment control. An understanding of these predictors will inform the development of tailored risk communication resources and preventive clinical strategies for RA., Competing Interests: Competing interests: SB, IW, DZ, GS, KR and MF declare they have no competing interests. CDM is funded by the National Institute for Health Research (NIHR) Applied Research Collaboration West Midlands, the National Institute for Health Research (NIHR) School for Primary Care Research and a National Institute for Health Research (NIHR) Research Professorship in General Practice (NIHR-RP-2014-04-026) for this research project. The School of Medicine has received financial support for a non-pharmacological study screening patients for AF in primary care., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY. Published by BMJ.)

Background: Cesarean delivery is the most common surgical procedure worldwide. Intrapartum fetal surveillance is routinely offered to improve neonatal outcomes, but the effects of different methods on the risk of emergency cesarean deliveries remains uncertain. We conducted a systematic review and network meta-analysis to evaluate the effectiveness of different types of fetal surveillance., Methods: We searched MEDLINE, Embase and CENTRAL until June 1, 2020, for randomized trials evaluating any intrapartum fetal surveillance method. We performed a network meta-analysis within a frequentist framework. We assessed the quality and network inconsistency of trials. We reported primarily on intrapartum emergency cesarean deliveries and other secondary maternal and neonatal outcomes using risk ratios (RRs) and 95% confidence intervals (CIs)., Results: We included 33 trials (118 863 patients) evaluating intermittent auscultation with Pinard stethoscope/handheld Doppler (IA), cardiotocography (CTG), computerized cardiotocography (cCTG), CTG with fetal scalp lactate (CTG-lactate), CTG with fetal scalp pH analysis (CTG-FBS), CTG with fetal pulse oximetry (FPO-CTG), CTG with fetal heart electrocardiogram (CTG-STAN) and their combinations. Intermittent auscultation reduced the risk of emergency cesarean deliveries compared with other types of surveillance (IA v. CTG: RR 0.83, 95% CI 0.72-0.97; IA v. CTG-FBS: RR 0.71, 95% CI 0.63-0.80; IA v.CTG-lactate: RR 0.77, 95% CI 0.64-0.92; IA v. FPO-CTG: RR 0.75, 95% CI 0.65-0.87; IA v.FPO-CTG-FBS: RR 0.81, 95% CI 0.67-0.99; cCTG-FBS v. IA: RR 1.21, 95% CI 1.04-1.42), except STAN-CTG-FBS (RR 1.17, 95% CI 0.98-1.40). There was a similar reduction observed for emergency cesarean deliveries for fetal distress. None of the evaluated methods was associated with a reduced risk of neonatal acidemia, neonatal unit admissions, Apgar scores or perinatal death., Interpretation: Compared with other types of fetal surveillance, intermittent auscultation seems to reduce emergency cesarean deliveries in labour without increasing adverse neonatal and maternal outcomes., Competing Interests: Competing interests: None declared., (© 2021 Joule Inc. or its licensors.)

Objectives: (1) To develop and internally-validate Euclidean Norm Minus One (ENMO) and Mean Amplitude Deviation (MAD) thresholds for separating sedentary behaviours from common light-intensity physical activities using raw acceleration data collected from both hip- and wrist-worn tri-axial accelerometers; and (2) to compare and evaluate the performances between the ENMO and MAD metrics., Methods: Thirty-three adults [mean age (standard deviation (SD)) = 27.4 (5.9) years; mean BMI (SD) = 23.9 (3.7) kg/m2; 20 females (60.6%)] wore four accelerometers; an ActiGraph GT3X+ and a GENEActiv on the right hip; and an ActiGraph GT3X+ and a GENEActiv on the non-dominant wrist. Under laboratory-conditions, participants performed 16 different activities (11 sedentary behaviours and 5 light-intensity physical activities) for 5 minutes each. ENMO and MAD were computed from the raw acceleration data, and logistic regression and receiver-operating-characteristic (ROC) analyses were implemented to derive thresholds for activity discrimination. Areas under ROC curves (AUROC) were calculated to summarise performances and thresholds were assessed via executing leave-one-out-cross-validations., Results: For both hip and wrist monitor placements, in comparison to the ActiGraph GT3X+ monitors, the ENMO and MAD values derived from the GENEActiv devices were observed to be slightly higher, particularly for the lower-intensity activities. Monitor-specific hip and wrist ENMO and MAD thresholds showed excellent ability for separating sedentary behaviours from motion-based light-intensity physical activities (in general, AUROCs >0.95), with validation indicating robustness. However, poor classification was experienced when attempting to isolate standing still from sedentary behaviours (in general, AUROCs <0.65). The ENMO and MAD metrics tended to perform similarly across activities and accelerometer brands., Conclusions: Researchers can utilise these robust monitor-specific hip and wrist ENMO and MAD thresholds, in order to accurately separate sedentary behaviours from common motion-based light-intensity physical activities. However, caution should be taken if isolating sedentary behaviours from standing is of particular interest., Competing Interests: The authors have declared that no competing interests exist.

Purpose: The objective of this study is to compare the accuracy of the activPAL and ActiGraph GT3X+ (waist and thigh) proprietary postural allocation algorithms and an open-source postural allocation algorithm applied to GENEActiv (thigh) and ActiGraph GT3X+ (thigh) data., Methods: Thirty-four adults (≥18 yr) wore the activPAL3, GENEActiv, and ActiGraph GT3X+ on the right thigh and an ActiGraph on the right hip while performing four lying, seven sitting, and five upright activities in the laboratory. Lying and sitting tasks incorporated a range of leg angles (e.g., lying with legs bent and sitting with legs crossed). Each activity was performed for 5 min while being directly observed. The percentage of the time the posture was correctly classified was calculated., Results: Participants consisted of 14 males and 20 females (mean age, 27.2 ± 5.9 yr; mean body mass index, 23.8 ± 3.7 kg·m). All postural allocation algorithms applied to monitors worn on the thigh correctly classified ≥93% of the time lying, ≥91% of the time sitting, and ≥93% of the time upright. The ActiGraph waist proprietary algorithm correctly classified 72% of the time lying, 58% of the time sitting, and 74% of the time upright. Both the activPAL and ActiGraph thigh proprietary algorithms misclassified sitting on a chair with legs stretched out (58% and 5% classified incorrectly, respectively). The ActiGraph thigh proprietary and open-source algorithm applied to the thigh-worn ActiGraph misclassified participants lying on their back with their legs bent 27% and 9% of the time, respectively., Conclusion: All postural allocation algorithms when applied to devices worn on the thigh were highly accurate in identifying lying, sitting, and upright postures. Given the poor accuracy of the waist algorithm for detecting sitting, caution should be taken if inferring sitting time from a waist-worn device.

Plant shoots have thick, polylamellate outer epidermal walls based on crossed layers of cellulose microfibrils, but the involvement of microtubules in such wall lamellation is unclear. Recently, using a long-term movie system in which Arabidopsis seedlings were grown in a biochamber, the tracks along which cortical microtubules move were shown to undergo slow rotary movements over the outer surface of hypocotyl epidermal cells. Because microtubules are known to guide cellulose synthases over the short term, we hypothesised that this previously unsuspected microtubule rotation could, over the longer term, help explain the cross-ply structure of the outer epidermal wall. Here, we test that hypothesis using Arabidopsis plants expressing the cellulose synthase GFP-CESA3 and show that cellulose synthase trajectories do rotate over several hours. Neither microtubule-stabilising taxol nor microtubule-depolymerising oryzalin affected the linear rate of GFP-CESA3 movement, but both stopped the rotation of cellulose synthase tracks. Transmission electron microscopy revealed that drug-induced suppression of rotation alters the lamellation pattern, resulting in a thick monotonous wall layer. We conclude that microtubule rotation, rather than any hypothetical mechanism for wall self-assembly, has an essential role in developing cross-ply wall texture.

The glucose-6-phosphate/phosphate antiporter GPT1 is a major route of entry of carbon into non-photosynthetic plastids. To discover its importance in oilseeds, we used a seed-specific promoter to generate lines of Arabidopsis thaliana with reduced levels of GPT1 in developing embryos. Strong reductions resulted in seed abortion at the end of the globular stage of embryo development, when proplastids in normal embryos differentiate and acquire chlorophyll. Seed abortion was partly dependent on the light level during silique development. Embryos in seeds destined for abortion failed to undergo normal morphogenesis and were 'raspberry-like' in appearance. They had ultrastructural and biochemical defects including proliferation of peroxisomes and starch granules, and altered expression of genes involved in starch turnover and the oxidative pentose phosphate pathway. We propose that GPT1 is necessary for early embryo development because it catalyses import into plastids of glucose-6-phosphate as the substrate for NADPH generation via the oxidative pentose phosphate pathway. We suggest that low NADPH levels during plastid differentiation and chlorophyll synthesis may result in generation of reactive oxygen species and triggering of embryo cell death., (© 2010 John Innes Centre. Journal compilation © 2010 Blackwell Publishing Ltd.)

A new nodulation-defective mutant of Lotus japonicus does not initiate nodule cortical cell division in response to Mesorhizobium loti, but induces root hair deformation, Nod factor-induced calcium spiking, and mycorrhization. This phenotype, together with mapping data, suggested that the mutation could be in the ortholog of the Medicago truncatula NSP1 gene (MtNSP1). The sequence of the orthologous gene (LjNSP1) in the L. japonicus mutant (Ljnsp1-1) revealed a mutation causing a premature stop resulting in loss of the C-terminal 23 amino acids. We also sequenced the NSP2 gene from L. japonicus (LjNSP2). A mutant (Ljnsp2-3) with a premature stop codon was identified by TILLING showing a similar phenotype to Ljnsp1-1. Both LjNSP1 and LjNSP2 are predicted GRAS (GAI, RGA, SCR) domain transcriptional regulators. Transcript steady-state levels of LjNSP1 and LjNSP2 initially decreased and then increased following infection by M. loti. In hairy root transformations, LjNSP1 and MtNSP1 complemented both Mtnsp1-1 and Ljnsp1-1 mutants, demonstrating that these orthologous proteins have a conserved biochemical function. A Nicotiana benthamiana NSP1-like gene (NbNSP1) was shown to restore nodule formation in both Ljnsp1-1 and Mtnsp1-1 mutants, indicating that NSP1 regulators from legumes and non-legumes can propagate the Nod factor-induced signal, activating appropriate downstream targets. The L. japonicus nodules complemented with NbNSP1 contained some cells with abnormal bacteroids and could fix nitrogen. However, the NbNSP1-complemented M. truncatula nodules did not fix nitrogen and contained very few bacteria released from infection threads. These observations suggest that NSP1 is also involved in infection, bacterial release, and normal bacteroid formation in nodule cells.

Many angiosperm species produce cones of anthers which release pollen through pores in response to vibration by pollinating bees ("buzz-pollination"). Anther cones of varying degrees of strength are a defining morphological trait for the genus Solanum. Anthers arranged in a robust ('pepper pot') cone are restricted to a single clade within the genus, and may therefore be assumed to be monophyletic. We show that in some species within this clade, such as tomato (Solanum lycopersicum), the anther cone is held together by interlocking hairs (trichomes) along the edges of the anthers. In other species within the clade, such as woody nightshade (Solanum dulcamara), the expanded anther surfaces are closely appressed to form the tightly bound cone, strengthened by extracellular secretions. Ectopic expression of the MIXTA gene from Antirrhinum majus in S. dulcamara results in the formation of ectopic trichomes on the anthers which cause the cone to disintegrate. Therefore, these two species produce the same macroscopic structure through two mutually exclusive developmental routes and the robust anther cone is derived differently within the clade. This example demonstrates that convergence between closely related species can be easily mistaken for homology, and may thus be underestimated.