PIONEER REAL Sweden: A Multicentre, Prospective, Real-World Observational Study of Oral Semaglutide Use in Adults with Type 2 Diabetes in Swedish Clinical Practice.

INTRODUCTION: The study was designed to assess outcomes with once-daily oral semaglutide in adults with type 2 diabetes (T2D) naïve to injectable glucose-lowering agents, in Swedish clinical practice. METHODS: In this non-interventional, multicentre study, participants initiated oral semaglutide and were followed for 34-44 weeks. The primary endpoint was glycated haemoglobin (HbA1c) change from baseline to end of study (EOS). Secondary endpoints included body weight (BW) change from baseline to EOS, proportion of participants achieving HbA1c < 7%, and proportion achieving both a HbA1c reduction ≥ 1% and BW reduction of ≥ 3% or ≥ 5%, at EOS. Participants completed Diabetes Treatment Satisfaction Questionnaires (DTSQ status/change) and a dosing conditions questionnaire. RESULTS: A total of 187 participants (mean age 62.5 years) initiated oral semaglutide. Baseline mean HbA1c and BW were 7.8% (n = 177) and 96.9 kg (n = 165), respectively. Estimated mean changes in HbA1c and BW were - 0.88%-points (95% confidence interval [CI] - 1.01 to - 0.75; P < 0.0001) and - 4.72% (95% CI - 5.58 to - 3.86; P < 0.0001), respectively. At EOS, 64.6% of participants had HbA1c < 7%, and 22.9% achieved HbA1c reduction of ≥ 1% and BW reduction of ≥ 5%. DTSQ status and change scores improved by 1.44 (P = 0.0260) and 12.3 points (P < 0.0001), respectively. Oral semaglutide was easy or very easy to consume for 86.4% of participants. Most common adverse events (AEs) were gastrointestinal disorders; nine participants (4.8%) had serious AEs; one (0.5%) experienced severe hypoglycaemia. CONCLUSION: In this real-world study population, we observed significant reductions in HbA1c and BW in people living with T2D when prescribed semaglutide tablets as part of routine clinical practice in Sweden, with improved treatment satisfaction among participants and no new safety concerns. TRIAL REGISTRATION: NCT04601753.

Changing diagnostic criteria for gestational diabetes (CDC4G) in Sweden: A stepped wedge cluster randomised trial.

BACKGROUND: The World Health Organisation (WHO) 2013 diagnostic criteria for gestational diabetes mellitus (GDM) has been criticised due to the limited evidence of benefits on pregnancy outcomes in different populations when switching from previously higher glycemic thresholds to the lower WHO-2013 diagnostic criteria. The aim of this study was to determine whether the switch from previous Swedish (SWE-GDM) to the WHO-2013 GDM criteria in Sweden following risk factor-based screening improves pregnancy outcomes. METHODS AND FINDINGS: A stepped wedge cluster randomised trial was performed between January 1 and December 31, 2018 in 11 clusters (17 delivery units) across Sweden, including all pregnancies under care and excluding preexisting diabetes, gastric bypass surgery, or multifetal pregnancies from the analysis. After implementation of uniform clinical and laboratory guidelines, a number of clusters were randomised to intervention (switch to WHO-2013 GDM criteria) each month from February to November 2018. The primary outcome was large for gestational age (LGA, defined as birth weight >90th percentile). Other secondary and prespecified outcomes included maternal and neonatal birth complications. Primary analysis was by modified intention to treat (mITT), excluding 3 clusters that were randomised before study start but were unable to implement the intervention. Prespecified subgroup analysis was undertaken among those discordant for the definition of GDM. Multilevel mixed regression models were used to compare outcome LGA between WHO-2013 and SWE-GDM groups adjusted for clusters, time periods, and potential confounders. Multiple imputation was used for missing potential confounding variables. In the mITT analysis, 47 080 pregnancies were included with 6 882 (14.6%) oral glucose tolerance tests (OGTTs) performed. The GDM prevalence increased from 595/22 797 (2.6%) to 1 591/24 283 (6.6%) after the intervention. In the mITT population, the switch was associated with no change in primary outcome LGA (2 790/24 209 (11.5%) versus 2 584/22 707 (11.4%)) producing an adjusted risk ratio (aRR) of 0.97 (95% confidence interval 0.91 to 1.02, p = 0.26). In the subgroup, the prevalence of LGA was 273/956 (28.8%) before and 278/1 239 (22.5%) after the switch, aRR 0.87 (95% CI 0.75 to 1.01, p = 0.076). No serious events were reported. Potential limitations of this trial are mainly due to the trial design, including failure to adhere to guidelines within and between the clusters and influences of unidentified temporal variations. CONCLUSIONS: In this study, implementing the WHO-2013 criteria in Sweden with risk factor-based screening did not significantly reduce LGA prevalence defined as birth weight >90th percentile, in the total population, or in the subgroup discordant for the definition of GDM. Future studies are needed to evaluate the effects of treating different glucose thresholds during pregnancy in different populations, with different screening strategies and clinical management guidelines, to optimise women's and children's health in the short and long term. TRIAL REGISTRATION: The trial is registered with ISRCTN (41918550).

A comparison of Swedish IBS patients and general practitioners regarding viewpoints on IBS: a Q-methodology study.

OBJECTIVES: Irritable bowel syndrome (IBS) is a common functional gastrointestinal condition. A respectful patient-doctor relationship with good communication is crucial for optimal treatment. Q-methodology is a combination of qualitative and quantitative methods used to study subjectivity. The aim of this study was to compare viewpoints on IBS between patients with IBS and general practitioners (GPs). METHODS: We conducted a Q-methodology study by including 30 patients and 30 GPs. All participants were asked to complete Q- sorting of 66 statements on IBS using an online software program. Data were processed using factor analysis. In addition, 3 patients and 3 GPs were interviewed. RESULTS: Three factors were extracted from both groups: Patient Factor 1 'Question the diagnosis of IBS', Patient Factor 2 'Lifestyle changes for a physical disorder', Patient Factor 3 'Importance of a diagnosis', GP Factor 1 'Unknown causes of great suffering', GP Factor 2 'Lifestyle changes are important, stress makes IBS worse', GP Factor 3 'Recognized the way IBS affects patients'. There was a strong and statistically significant correlation between patient Factor 1 and GP Factor 1, with a Pearson's r of 0.81 (p < 0.001). Correlations between other factors varied. CONCLUSIONS: There was consensus between patients and GPs that IBS is a physical and not a psychiatric disorder of unknown etiology. They also seemed to agree that IBS has a great negative impact on patients' lives and that lifestyle changes are beneficial. There were conflicting opinions regarding gender, cultural factors and the use of antidepressants.

ChloroSpec: A new in vivo chlorophyll fluorescence spectrometer for simultaneous wavelength- and time-resolved detection.

Chlorophyll fluorescence is a ubiquitous tool in basic and applied plant science research. Various standard commercial instruments are available for characterization of photosynthetic material like leaves or microalgae, most of which integrate the overall fluorescence signals above a certain cut-off wavelength. However, wavelength-resolved (fluorescence signals appearing at different wavelengths having different time dependent decay) signals contain vast information required to decompose complex signals and processes into their underlying components that can untangle the photo-physiological process of photosynthesis. Hence, to address this we describe an advanced chlorophyll fluorescence spectrometer - ChloroSpec - allowing three-dimensional simultaneous detection of fluorescence intensities at different wavelengths in a time-resolved manner. We demonstrate for a variety of typical examples that most of the generally used fluorescence parameters are strongly wavelength dependent. This indicates a pronounced heterogeneity and a highly dynamic nature of the thylakoid and the photosynthetic apparatus under actinic illumination. Furthermore, we provide examples of advanced global analysis procedures integrating this three-dimensional signal and relevant information extracted from them that relate to the physiological properties of the organism. This conveniently obtained broad range of data can make ChloroSpec a new standard tool in photosynthesis research.

Levels of Physical Activity, Enjoyment, Self-Efficacy for Exercise, and Social Support Before and After Metabolic and Bariatric Surgery: a Longitudinal Prospective Observational Study.

INTRODUCTION: Physical activity (PA) after metabolic and bariatric surgery (MBS) can influence weight loss, health status, and quality of life. Known mediators to participate in PA are enjoyment, self-efficacy, and social support. Little is known about PA behavior in MBS individuals. The aim of this study was to explore levels of PA and the PA mediators enjoyment, self-efficacy, and social support before and after MBS and to investigate changes over time. METHODS: Adults scheduled to undergo MBS were recruited from a Swedish university hospital. Accelerometer-measured and self-reported PA, body weight, and PA mediators were collected at baseline and at 12 to 18 months post-surgery. RESULTS: Among 90 individuals included, 50 completed the follow-up assessment and had valid accelerometer data. Sedentary time (minutes/day) was unchanged, but sedentary time as percentage of wear time decreased significantly from 67.2% to 64.5% (p<0.05). Time spent in light PA and total PA increased significantly from 259.3 to 288.7 min/day (p < 0.05) and from 270.5 to 303.5 min/day (p < 0.01), respectively. Step counts increased significantly from 6013 to 7460 steps/day (p < 0.01). There was a significant increase in self-reported PA, enjoyment, self-efficacy for exercise, and positive social support from family. The increase in PA mediators did not lead to a significant change in time spent in moderate to vigorous PA. CONCLUSION: The increase in PA-mediators was not associated with an increase in moderate to vigorous PA, but the strengthened PA mediators suggest potential for an increase in moderate to vigorous PA in patients undergoing MBS.

Hypertension management in primary health care: a survey in eight regions of Sweden.

PURPOSE: To explore hypertension management in primary healthcare (PHC). DESIGN: Structured interviews of randomly selected PHC centres (PHCCs) from December 2019 to January 2021. SETTING: Seventy-six PHCCs in eight regions of Sweden. MAIN OUTCOME MEASURES: Staffing and organization of hypertension care. Methods of measuring blood pressure (BP), laboratory tests, registration of co-morbidities and lifestyle advice at diagnosis and follow-up. RESULTS: The management of hypertension varied among PHCCs. At diagnosis, most PHCCs (75%) used the sitting position at measurements, and only 13% routinely measured standing BP. One in three (33%) PHCCs never used home BP measurements and 25% only used manual measurements. The frequencies of laboratory analyses at diagnosis were similar in the PHCCs. At follow-up, fewer analyses were performed and the tests of lipids and microalbuminuria decreased from 95% to 45% (p < 0.001) and 61% to 43% (p = 0.001), respectively. Only one out of 76 PHCCs did not measure kidney function at routine follow-ups. Lifestyle, physical activity, food habits, smoking and alcohol use were assessed in ≥96% of patients at diagnosis. At follow-up, however, there were fewer assessments. Half of the PHCCs reported dedicated teams for hypertension, 82% of which were managed by nurses. There was a great inequality in the number of patients per tenured GP in the PHCCs (median 2500; range 1300-11300) patients. CONCLUSIONS: The management of hypertension varies in many respects between PHCCs in Sweden. This might lead to inequity in the care of patients with hypertension.

Hypertension is mainly handled in primary healthcare (PHC), and this study shows important dissimilarities in organization and clinical management.Several variants in techniques and measurements of blood pressure were found between PHC centres.Lifestyle, clinical and laboratory assessments decreased at follow-ups compared to at diagnosis, specifically for lipids, microalbuminuria and electrocardiograms.Nearly half of the PHC centres reported that they had dedicated hypertension teams.

Salicylic acid metabolism and signalling coordinate senescence initiation in aspen in nature.

Deciduous trees exhibit a spectacular phenomenon of autumn senescence driven by the seasonality of their growth environment, yet there is no consensus which external or internal cues trigger it. Senescence starts at different times in European aspen (Populus tremula L.) genotypes grown in same location. By integrating omics studies, we demonstrate that aspen genotypes utilize similar transcriptional cascades and metabolic cues to initiate senescence, but at different times during autumn. The timing of autumn senescence initiation appeared to be controlled by two consecutive "switches"; 1) first the environmental variation induced the rewiring of the transcriptional network, stress signalling pathways and metabolic perturbations and 2) the start of senescence process was defined by the ability of the genotype to activate and sustain stress tolerance mechanisms mediated by salicylic acid. We propose that salicylic acid represses the onset of leaf senescence in stressful natural conditions, rather than promoting it as often observed in annual plants.

Health care registers can be instrumental for endpoint capture in clinical diabetes trials: example of microvascular complications in Swedish patients with type 2 diabetes.

AIMS: SMARTEST is a register-based randomized clinical trial (RRCT) that compares dapagliflozin to metformin in early-stage type 2 diabetes. The primary outcome includes progression of microvascular complications based on data from the Swedish National Diabetes Register (NDR). In this sub-study, the aim was to validate microvascular complication variables in the NDR against electronic health records (EHRs). METHODS: Data were extracted from EHRs of 276 SMARTEST participants with a median observation period of 3 years in the Uppsala, Örebro and Sörmland counties and compared with NDR data. Agreement was determined for all corresponding data entries as well as for progression of microvascular complications after randomization. RESULTS: The agreement for all corresponding data entries was 98.9% (Intraclass Correlation Coefficient 0.999) for creatinine and eGFR, 95.1% for albuminuria, 91.6% for foot-at-risk and 98.2% for retinopathy status (Kappa 0.67-0.91). The agreement for progression of microvascular complications was 98.0% for CKD stage, 98.9% for albuminuria grade, 96.3% for foot-at-risk grade and 99.6% for retinopathy grade progression (Gwet's AC1 0.96-1.00). CONCLUSION: Microvascular complication variables in the NDR show good agreement with EHR data. The use of a well-established national health care registry, exemplified by the NDR, for endpoint collection in RRCTs such as SMARTEST is supported by this study.

Flavodiiron-mediated O2 photoreduction at photosystem I acceptor-side provides photoprotection to conifer thylakoids in early spring.

Green organisms evolve oxygen (O2) via photosynthesis and consume it by respiration. Generally, net O2 consumption only becomes dominant when photosynthesis is suppressed at night. Here, we show that green thylakoid membranes of Scots pine (Pinus sylvestris L) and Norway spruce (Picea abies) needles display strong O2 consumption even in the presence of light when extremely low temperatures coincide with high solar irradiation during early spring (ES). By employing different electron transport chain inhibitors, we show that this unusual light-induced O2 consumption occurs around photosystem (PS) I and correlates with higher abundance of flavodiiron (Flv) A protein in ES thylakoids. With P700 absorption changes, we demonstrate that electron scavenging from the acceptor-side of PSI via O2 photoreduction is a major alternative pathway in ES. This photoprotection mechanism in vascular plants indicates that conifers have developed an adaptative evolution trajectory for growing in harsh environments.

Genetic markers and tree properties predicting wood biorefining potential in aspen (Populus tremula) bioenergy feedstock.

BACKGROUND: Wood represents the majority of the biomass on land and constitutes a renewable source of biofuels and other bioproducts. However, wood is recalcitrant to bioconversion, raising a need for feedstock improvement in production of, for instance, biofuels. We investigated the properties of wood that affect bioconversion, as well as the underlying genetics, to help identify superior tree feedstocks for biorefining. RESULTS: We recorded 65 wood-related and growth traits in a population of 113 natural aspen genotypes from Sweden ( https://doi.org/10.5061/dryad.gtht76hrd ). These traits included three growth and field performance traits, 20 traits for wood chemical composition, 17 traits for wood anatomy and structure, and 25 wood saccharification traits as indicators of bioconversion potential. Glucose release after saccharification with acidic pretreatment correlated positively with tree stem height and diameter and the carbohydrate content of the wood, and negatively with the content of lignin and the hemicellulose sugar units. Most of these traits displayed extensive natural variation within the aspen population and high broad-sense heritability, supporting their potential in genetic improvement of feedstocks towards improved bioconversion. Finally, a genome-wide association study (GWAS) revealed 13 genetic loci for saccharification yield (on a whole-tree-biomass basis), with six of them intersecting with associations for either height or stem diameter of the trees. CONCLUSIONS: The simple growth traits of stem height and diameter were identified as good predictors of wood saccharification yield in aspen trees. GWAS elucidated the underlying genetics, revealing putative genetic markers for bioconversion of bioenergy tree feedstocks.

A lifelong struggle for a lighter tomorrow: A qualitative study on experiences of obesity in primary healthcare patients.

AIM: To describe experiences of living with obesity before the start of a group-based lifestyle intervention. BACKGROUND: Obesity is a chronic disease that affects a person's physical and psychological health. Increased knowledge of experiences of living with obesity is required. DESIGN: A qualitative study with a descriptive design. METHODS: Semi-structured individual interviews with 17 participants living with obesity (Body Mass Index 32-49) were conducted between October and November 2019. The interviews were analysed using qualitative content analysis. The COREQ checklist was followed. RESULTS: The analysis resulted in one main theme: Struggling for a lighter tomorrow and three subthemes: Suffering, Resilience and Need for support in making changes. For the majority of the participants, living with obesity was a lifelong struggle involving suffering on different levels. Yet despite this, the participants had not given up and hoped for a better life. They showed a degree of resilience and motivation, and a perceived ability to achieve lifestyle changes. However, there was a pronounced need for support to help them achieve this. CONCLUSION: Living with obesity is complex and carries a risk of medical complications as well as psychosocial suffering. Healthy lifestyle habits to achieve better health and to lose weight should be encouraged, taking patient resources into account. Patients also need help in handling weight stigmatisation, and both healthcare professionals and society must engage with this. RELEVANCE TO CLINICAL PRACTICE: Obesity is a chronic disease, and patients need ongoing support. Therefore, care for patients with obesity in primary health care must be further developed. Patient resources and strengths have to be acknowledged and encouraged in the process of helping them adopt healthy lifestyle habits. The findings of this study can contribute to ending weight stigmatisation by increasing the knowledge of living with obesity.

Dog ownership, glycaemic control and all-cause death in patients with newly diagnosed type 2 diabetes: a national cohort study.

Aims: To evaluate whether dog ownership from the time of type 2 diabetes diagnosis improved glycaemic control, increased achievement of major guideline treatment goals or reduced the risk of all-cause death. Methods: Patients diagnosed with type 2 diabetes were followed by linkage of four Swedish national registers covering diabetes, dog ownership, socioeconomics, and mortality. Linear regression was used to estimate the mean yearly change in glycated haemoglobin (HbA1c). Cox survival analysis and logistic regression were used to analyse associations between dog ownership and all-cause death and achievement of treatment goals, respectively. Results: Of 218,345 individuals included, 8,352 (3.8%) were dog-owners. Median follow-up was 5.2 years. Dog-owners had worse yearly change in HbA1c, and were less likely to reach HbA1c, low-density lipoprotein (LDL), and systolic blood pressure (SBP) treatment goals than non-dog-owners (adjusted odds ratios [95% CI] of 0.93 [0.88-0.97], 0.91 [0.86-0.95], and 0.95 [0.90-1.00], respectively). There was no difference in the risk of all-cause death (adjusted hazard ratio [95% CI] 0.92 [0.81-1.04], dog owners versus not). Conclusion: Owning a dog when diagnosed with diabetes did not lead to better achievement of treatment goals or reduced mortality, but was in fact associated with a smaller reduction in HbA1c and reduced likelihood of achieving treatment goals.

Use of faecal immunochemical tests common in patients with suspected colorectal cancer but unrelated to travel distance to secondary care: a population-based study from Swedish primary care.

BACKGROUND: Evidence is increasing for the use of faecal immunochemical tests (FITs) for occult blood as diagnostic tools when colorectal cancer can be suspected. FITs have been used for this purpose in Swedish primary care since around 2005 despite absence of supporting guidelines. To our knowledge, the extent of this use has not been studied. OBJECTIVE: To investigate the use of FITs as diagnostic tools, and if the use was related to patient age, sex and travel time from primary care to diagnostic facilities in secondary care. DESIGN: Population-based retrospective study using data from electronic health records. SETTING AND SUBJECTS: Patients ≥18 years that provided FITs in primary care in five Swedish health care regions during 2015. Driving times from their primary care centres to secondary care were calculated. MAIN OUTCOME MEASURES: The proportion of patients that provided FITs was calculated for each region, different age intervals and grouped driving times. RESULTS: 18,913 patients provided FITs. The proportion of listed patients in the five regions that provided FITs increased with age: 0.86-1.2% for ages <65 years, 3.6-4.1% for ages 65-79 years and 3.8-6.1% for ages ≥80 years. Differences between the regions were small. There was no overall correlation between the proportion of patients that provided FITs and driving time to secondary care. CONCLUSION: FITs were used extensively in Swedish primary care with a higher use in older age groups. There was no tendency towards a higher use of FITs at primary care centres with longer driving times to secondary care.Key PointsEvidence is increasing for the use of faecal immunochemical tests (FITs) as diagnostic tools when colorectal cancer can be suspected. We investigated the use of FITs in Sweden.FITs were used extensively in primary care especially in older age groups.There were small differences in the use of FITs between five studied health care regions.There was no tendency towards a higher use of FITs at primary care centres with longer driving times to diagnostic facilities in secondary care.

The RPN12a proteasome subunit is essential for the multiple hormonal homeostasis controlling the progression of leaf senescence.

The 26S proteasome is a conserved multi-subunit machinery in eukaryotes. It selectively degrades ubiquitinated proteins, which in turn provides an efficient molecular mechanism to regulate numerous cellular functions and developmental processes. Here, we studied a new loss-of-function allele of RPN12a, a plant ortholog of the yeast and human structural component of the 19S proteasome RPN12. Combining a set of biochemical and molecular approaches, we confirmed that a rpn12a knock-out had exacerbated 20S and impaired 26S activities. The altered proteasomal activity led to a pleiotropic phenotype affecting both the vegetative growth and reproductive phase of the plant, including a striking repression of leaf senescence associate cell-death. Further investigation demonstrated that RPN12a is involved in the regulation of several conjugates associated with the auxin, cytokinin, ethylene and jasmonic acid homeostasis. Such enhanced aptitude of plant cells for survival in rpn12a contrasts with reports on animals, where 26S proteasome mutants generally show an accelerated cell death phenotype.

Editor's Choice - Incidence of Lower Limb Amputations in Sweden from 2008 to 2017.

OBJECTIVE: This study examined the recent national and regional incidence of lower limb amputations (LLAs) in Sweden and their annual changes. METHODS: This was an observational study using Swedish national register data. All initial amputations were identified in Sweden from 2008 to 2017 in individuals 18 years or older using the national inpatient register. The amputations were categorised into three levels: high proximal (through or above the knee joint), low proximal (through the tibia to through the ankle joint), and partial foot amputations. To examine the national and regional incidence and annual changes, the age, sex, and region specific population count each year was used as the denominator and Poisson regression or negative binomial regression models were used to estimate incidence rate ratios (IRRs) and 95% confidence intervals (CIs) adjusted for age and sex. RESULTS: The national annual incidence of LLAs was 22.1 per 100 000 inhabitants, with a higher incidence in men (24.2) than in women (20.0). The incidence of LLAs (all levels combined) declined during the study period, with an IRR of 0.984 per year (95% CI 0.973 - 0.994). This was mainly due to a decrease in high proximal amputations (0.985, 95% CI 0.974 - 0.995) and low proximal amputations (0.973, 95% CI 0.962 - 0.984). No change in the incidence of partial foot amputations was observed (0.994, 95% CI 0.974 - 1.014). Such declines in LLA incidence (all levels combined) were observed in nine of the 21 regions. Compared with the national average and with adjustment for age, sex, diabetes, and artery disease, the regional IRR varied from 0.85 to 1.36 for all LLAs, from 0.67 to 1.61 for high proximal amputations, from 0.50 to 1.51 for low proximal amputations, and from 0.13 to 3.68 for partial foot amputations. CONCLUSION: The incidence of LLAs has decreased in Sweden. However, regional variations in incidence, time trends, and amputation levels warrant further research.

A kaleidoscope of photosynthetic antenna proteins and their emerging roles.

Photosynthetic light-harvesting antennae are pigment-binding proteins that perform one of the most fundamental tasks on Earth, capturing light and transferring energy that enables life in our biosphere. Adaptation to different light environments led to the evolution of an astonishing diversity of light-harvesting systems. At the same time, several strategies have been developed to optimize the light energy input into photosynthetic membranes in response to fluctuating conditions. The basic feature of these prompt responses is the dynamic nature of antenna complexes, whose function readily adapts to the light available. High-resolution microscopy and spectroscopic studies on membrane dynamics demonstrate the crosstalk between antennae and other thylakoid membrane components. With the increased understanding of light-harvesting mechanisms and their regulation, efforts are focusing on the development of sustainable processes for effective conversion of sunlight into functional bio-products. The major challenge in this approach lies in the application of fundamental discoveries in light-harvesting systems for the improvement of plant or algal photosynthesis. Here, we underline some of the latest fundamental discoveries on the molecular mechanisms and regulation of light harvesting that can potentially be exploited for the optimization of photosynthesis.

Nitrate fertilization may delay autumn leaf senescence, while amino acid treatments do not.

Fertilization with nitrogen (N)-rich compounds leads to increased growth but may compromise phenology and winter survival of trees in boreal regions. During autumn, N is remobilized from senescing leaves and stored in other parts of the tree to be used in the next growing season. However, the mechanism behind the N fertilization effect on winter survival is not well understood, and it is unclear how N levels or forms modulate autumn senescence. We performed fertilization experiments and showed that treating Populus saplings with inorganic nitrogen resulted in a delay in senescence. In addition, by using precise delivery of solutes into the xylem stream of Populus trees in their natural environment, we found that delay of autumn senescence was dependent on the form of N administered: inorganic N ( NO 3 - ) delayed senescence, but amino acids (Arg, Glu, Gln, and Leu) did not. Metabolite profiling of leaves showed that the levels of tricarboxylic acids, arginine catabolites (ammonium, ornithine), glycine, glycine-serine ratio and overall carbon-to-nitrogen (C/N) ratio were affected differently by the way of applying NO3 - and Arg treatments. In addition, the onset of senescence did not coincide with soluble sugar accumulation in control trees or in any of the treatments. We propose that different regulation of C and N status through direct molecular signaling of NO3 - and/or different allocation of N between tree parts depending on N forms could account for the contrasting effects of NO3 - and tested here amino acids (Arg, Glu, Gln, and Leu) on autumn senescence.

Solubilization Method for Isolation of Photosynthetic Mega- and Super-complexes from Conifer Thylakoids.

Photosynthesis is the main process by which sunlight is harvested and converted into chemical energy and has been a focal point of fundamental research in plant biology for decades. In higher plants, the process takes place in the thylakoid membranes where the two photosystems (PSI and PSII) are located. In the past few decades, the evolution of biophysical and biochemical techniques allowed detailed studies of the thylakoid organization and the interaction between protein complexes and cofactors. These studies have mainly focused on model plants, such as Arabidopsis, pea, spinach, and tobacco, which are grown in climate chambers even though significant differences between indoor and outdoor growth conditions are present. In this manuscript, we present a new mild-solubilization procedure for use with "fragile" samples such as thylakoids from conifers growing outdoors. Here, the solubilization protocol is optimized with two detergents in two species, namely Norway spruce (Picea abies) and Scots pine (Pinus sylvestris). We have optimized the isolation and characterization of PSI and PSII multimeric mega- and super-complexes in a close-to-native condition by Blue-Native gel electrophoresis. Eventually, our protocol will not only help in the characterization of photosynthetic complexes from conifers but also in understanding winter adaptation.

GIGANTEA influences leaf senescence in trees in two different ways.

GIGANTEA (GI) genes have a central role in plant development and influence several processes. Hybrid aspen T89 (Populus tremula x tremuloides) trees with low GI expression engineered through RNAi show severely compromised growth. To study the effect of reduced GI expression on leaf traits with special emphasis on leaf senescence, we grafted GI-RNAi scions onto wild-type rootstocks and successfully restored growth of the scions. The RNAi line had a distorted leaf shape and reduced photosynthesis, probably caused by modulation of phloem or stomatal function, increased starch accumulation, a higher carbon-to-nitrogen ratio, and reduced capacity to withstand moderate light stress. GI-RNAi also induced senescence under long day (LD) and moderate light conditions. Furthermore, the GI-RNAi lines were affected in their capacity to respond to "autumn environmental cues" inducing senescence, a type of leaf senescence that has physiological and biochemical characteristics that differ from those of senescence induced directly by stress under LD conditions. Overexpression of GI delayed senescence under simulated autumn conditions. The two different effects on leaf senescence under LD or simulated autumn conditions were not affected by the expression of FLOWERING LOCUS T. GI expression regulated leaf senescence locally-the phenotype followed the genotype of the branch, independent of its position on the tree-and trees with modified gene expression were affected in a similar way when grown in the field as under controlled conditions. Taken together, GI plays a central role in sensing environmental changes during autumn and determining the appropriate timing for leaf senescence in Populus.