News about amino acid metabolism in plant–microbe interactions

Plants constantly come into contact with a diverse mix of pathogenic and beneficial microbes. The ability to distinguish between them and to respond appropriately is essential for plant health. Here we review recent progress in understanding the role of amino acid sensing, signaling, transport, and metabolism during plant–microbe interactions. Biochemical pathways converting individual amino acids into active compounds have recently been elucidated, and comprehensive large-scale approaches have brought amino acid sensors and transporters into focus. These findings show that plant central amino acid metabolism is closely interwoven with stress signaling and defense responses at various levels. The individual biochemical mechanisms and the interconnections between the different processes are just beginning to emerge and might serve as a foundation for new plant protection strategies

Isotope-Guided Metabolomics Reveals Divergent Incorporation of Valine into Different Flavor Precursor Classes in Chives

Plants of the genus Allium such as chives, onions or garlic produce S-alk(en)yl cysteine sulfoxides as flavor precursors. Two major representatives are S-propenyl cysteine sulfoxide (isoalliin) and S-propyl cysteine sulfoxide (propiin), which only differ by a double bond in the C3 side chain. The propenyl group of isoalliin is derived from the amino acid valine, but the source of the propyl group of propiin remains unclear. Here, we present an untargeted metabolomics approach in seedlings of chives (Allium schoenoprasum) to track mass features containing sulfur and/or 13C from labeling experiments with valine-13C5 guided by their isotope signatures. Our data show that propiin and related propyl-bearing metabolites incorporate carbon derived from valine-13C5, but to a much lesser extent than isoalliin and related propenyl compounds. Our findings provide new insights into the biosynthetic pathways of flavor precursors in Allium species and open new avenues for future untargeted labeling experiments

Artificial pancreas systems for people with type 2 diabetes: Conception and design of the european CLOSE project

In the last 10 years tremendous progress has been made in the development of artificial pancreas (AP) systems for people with type 1 diabetes (T1D). The pan-European consortium CLOSE (Automated Glucose Control at Home for People with Chronic Disease) is aiming to develop integrated AP solutions (APplus) tailored to the needs of people with type 2 diabetes (T2D). APplus comprises a product and service package complementing the AP system by obligatory training as well as home visits and telemedical consultations on demand. Outcome predictors and performance indicators shall help to identify people who could benefit most from AP usage and facilitate the measurement of AP impact in diabetes care. In a first step CLOSE will establish a scalable APplus model case working at the interface between patients, homecare service providers, and payers in France. CLOSE will then scale up APplus by pursuing geographic distribution, targeting additional audiences, and enhancing AP functionalities and interconnectedness. By being part of the European Institute of Innovation and Technology (EIT) Health public-private partnership, CLOSE is committed to the EIT “knowledge triangle” pursuing the integrated advancement of technology, education, and business creation. Putting stakeholders, education, and impact into the center of APplus advancement is considered key for achieving wide AP use in T2D care

Reduced expression of the polymeric immunoglobulin receptor in pancreatic and periampullary adenocarcinoma signifies tumour progression and poor prognosis

The polymeric immunoglobulin receptor (pIgR) is a key component of the mucosal immune system that mediates epithelial transcytosis of immunoglobulins. High pIgR expression has been reported to correlate with a less aggressive tumour phenotype and an improved prognosis in several human cancer types. Here, we examined the expression and prognostic significance of pIgR in pancreatic and periampullary adenocarcinoma. The study cohort encompasses a consecutive series of 175 patients surgically treated with pancreaticoduodenectomy for pancreatic and periampullary adenocarcinoma in Malmö and Lund University Hospitals, Sweden, between 2001-2011. Tissue microarrays were constructed from primary tumours (n = 175) and paired lymph node metastases (n = 105). A multiplied score was calculated from the fraction and intensity of pIgR staining. Classification and regression tree analysis was used to select the prognostic cut-off. Unadjusted and adjusted hazard ratios (HR) for death and recurrence within 5 years were calculated. pIgR expression could be evaluated in 172/175 (98.3%) primary tumours and in 96/105 (91.4%) lymph node metastases. pIgR expression was significantly down-regulated in lymph node metastases as compared with primary tumours (p = 0.018). Low pIgR expression was significantly associated with poor differentiation grade (p < 0.001), perineural growth (p = 0.027), lymphatic invasion (p = 0.016), vascular invasion (p = 0.033) and infiltration of the peripancreatic fat (p = 0.039). In the entire cohort, low pIgR expression was significantly associated with an impaired 5-year survival (HR = 2.99, 95% confidence interval (CI) 1.71-5.25) and early recurrence (HR = 2.89, 95% CI 1.67-4.98). This association remained significant for survival after adjustment for conventional clinicopathological factors, tumour origin and adjuvant treatment (HR = 1.98, 95% CI 1.10-3.57). These results demonstrate, for the first time, that high tumour-specific pIgR expression signifies a more favourable tumour phenotype and that low expression independently predicts a shorter survival in patients with pancreatic and periampullary cancer. The mechanistic basis for the putative tumour suppressing properties of pIgR in these cancers merits further study

Amino acid metabolism under drought stress in Arabidopsis thaliana

Abstract: Due to climate change, drought periods will occur more frequently in the future. They will have a strong negative impact on crop yields. Drought stress leads to an osmotic imbalance and causes the closure of stomata to reduce water loss of transpiration. However, this reduces photosynthesis and ultimately leads to the formation of oxygen radicals, which may damage cell structure and function. If drought stress continues, a dramatic lack of energy is caused, which threatens plant life. To prevent irreversible damage, plants adapt their entire metabolism to resist drought stress at an early stage. This dissertation is dedicated to the adaptation of plants upon drought stress and the specific contribution of amino acid metabolism during this process. An in vitro experiment was performed to investigate the implications of a short but severe water deficit (Chapter 2.1). The Arabidopsis seedlings showed a strong decrease in protein content within 24h and at the same time a strong accumulation of the amino acids L-proline and GABA. Proteome analyses revealed that the aromatic amino acids were primarily used for the synthesis of stress mitigating secondary metabolites, such as flavonoids and anthocyanins, which are known to scavenge reactive oxygen species. Furthermore, a general induction of amino acid catabolism was observed, which provides sufficient amounts of L-glutamate for the synthesis of L-proline and GABA. Simultaneously, the catabolic pathways could represent an alternative source of reduction equivalents, which may fuel mitochondrial ATP production under carbon starvation conditions. In soil experiments were performed to investigate the plant drought stress response in a more physiological context (Chapter 2.2). In both, the in vitro and the in soil system, the plant stress response can be divided into distinct phases. The osmotically active amino acids, L-proline and GABA, are already produced in early phases of the water deficit and allow keeping the cellular water content constant for several days. Shortly before plants become irreversibly impaired by drought, a massive protein degradation takes place. This marks the beginning of the severe stress phase. Based on the proteome data and theoretical considerations, an experimental strategy was developed, which allows calculating absolute contents, concentrations and even copy numbers of individual proteins per leaf cell. As a result, the dynamic interconnection of protein homeostasis and amino acid homeostasis could be monitored and quantified on absolute scales. Our approach reveals the energy content of the released amino acids and indicates that their complete oxidation would cover the energy demand of the plant for several hours. In a review article, the regulatory properties of amino acids during the plant stress response were summarized and discussed (Chapter 2.3): Amino acids can be used as signal molecules, e.g. for inducing stomatal closure, as sensors of the nutrient content of cells or regulators for inducing their own catabolism. Our findings contribute to a general understanding of the effects of drought stress on the plant metabolism and shed light on the versatile and important roles of amino acids beyond their role in representing building blocks for protein biosynthesis

Land surface temperature trends as indicator of land use changes in wetlands

The impacts of agricultural expansion on wetlands are diverse and complex. Land surface temperature (LST) has a great potential to act as a global indicator of the status of wetlands and changes in their hydrological and evapotranspiration regimes, which are often linked to land use and cover changes. We use the whole MODIS LST archive (2000–2017) to perform time series analysis in the Kilombero catchment, Tanzania; a large wetland that has experienced major land conversions to agriculture during the last two decades. We estimated pixel based trends using three models: a seasonal trend model, and aggregated time series using annual means and percentile 90. We characterized the trends found by using land cover change maps derived from Landsat imagery and a post-classification comparison. The relation between Normalized Difference Vegetation Index (NDVI) and LST trends was also studied (r =−0.56). The results given by the seasonal trend model and annual means were similar (r = 0.81). Fewer significant trends were found using the percentile 90, and these had larger magnitudes. Positive LST trends (i.e. increasing) corresponded to deforestation and farmland expansion into the floodplain, while forestation processes resulted in negative LST trends. Moderate increases of LST in natural wetlands suggest that the impacts of human activities extend also into non-cultivated areas. We provide evidence of how time series analysis of LST data can be successfully used to monitor and study changes in wetland ecosystems at regional and local scale

The role of amino acid metabolism during abiotic stress release

Plant responses to abiotic stress include various modifications in amino acid metabolism. By using a hydroponic culture system, we systematically investigate modification in amino acid profiles and the proteome of Arabidopsis thaliana leaves during initial recovery from low water potential or high salinity. Both treatments elicited oxidative stress leading to a biphasic stress response during recovery. Degradation of highly abundant proteins such as subunits of photosystems and ribosomes contributed to an accumulation of free amino acids. Catabolic pathways for several low abundant amino acids were induced indicating their usage as an alternative respiratory substrate to compensate for the decreased photosynthesis. Our results demonstrate that rapid detoxification of potentially detrimental amino acids such as Lys is a priority during the initial stress recovery period. The content of Pro, which acts as a compatible osmolyte during stress, was adjusted by balancing its synthesis and catabolism both of which were induced both during and after stress treatments. The production of amino acid derived secondary metabolites was up‐regulated specifically during the recovery period, and our dataset also indicates increased synthesis rates of the precursor amino acids. Overall, our results support a tight relationship between amino acid metabolism and stress responses

The role of amino acid metabolism during abiotic stress release

Plant responses to abiotic stress include various modifications in amino acid metabolism. By using a hydroponic culture system, we systematically investigate modification in amino acid profiles and the proteome of Arabidopsis thaliana leaves during initial recovery from low water potential or high salinity. Both treatments elicited oxidative stress leading to a biphasic stress response during recovery. Degradation of highly abundant proteins such as subunits of photosystems and ribosomes contributed to an accumulation of free amino acids. Catabolic pathways for several low abundant amino acids were induced indicating their usage as an alternative respiratory substrate to compensate for the decreased photosynthesis. Our results demonstrate that rapid detoxification of potentially detrimental amino acids such as Lys is a priority during the initial stress recovery period. The content of Pro, which acts as a compatible osmolyte during stress, was adjusted by balancing its synthesis and catabolism both of which were induced both during and after stress treatments. The production of amino acid derived secondary metabolites was up‐regulated specifically during the recovery period, and our dataset also indicates increased synthesis rates of the precursor amino acids. Overall, our results support a tight relationship between amino acid metabolism and stress responses

Artificial Pancreas Systems for People With Type 2 Diabetes: Conception and Design of the European CLOSE Project.

In the last 10 years tremendous progress has been made in the development of artificial pancreas (AP) systems for people with type 1 diabetes (T1D). The pan-European consortium CLOSE (Automated Glu cose Contro l at H ome for People with Chronic Disea se) is aiming to develop integrated AP solutions (APplus) tailored to the needs of people with type 2 diabetes (T2D). APplus comprises a product and service package complementing the AP system by obligatory training as well as home visits and telemedical consultations on demand. Outcome predictors and performance indicators shall help to identify people who could benefit most from AP usage and facilitate the measurement of AP impact in diabetes care. In a first step CLOSE will establish a scalable APplus model case working at the interface between patients, homecare service providers, and payers in France. CLOSE will then scale up APplus by pursuing geographic distribution, targeting additional audiences, and enhancing AP functionalities and interconnectedness. By being part of the European Institute of Innovation and Technology (EIT) Health public-private partnership, CLOSE is committed to the EIT "knowledge triangle" pursuing the integrated advancement of technology, education, and business creation. Putting stakeholders, education, and impact into the center of APplus advancement is considered key for achieving wide AP use in T2D care.status: publishe