KIN3 impacts arbuscular mycorrhizal symbiosis and promotes fungal colonisation in Medicago truncatula.

Arbuscular mycorrhizal fungi help their host plant in the acquisition of nutrients, and this association is itself impacted by soil nutrient levels. High phosphorus levels inhibit the symbiosis, whereas high nitrogen levels enhance it. The genetic mechanisms regulating the symbiosis in response to soil nutrients are poorly understood. Here, we characterised the symbiotic phenotypes in four Medicago truncatula Tnt1-insertion mutants affected in arbuscular mycorrhizal colonisation. We located their Tnt1 insertions and identified alleles for two genes known to be involved in mycorrhization, RAM1 and KIN3. We compared the effects of the kin3-2 and ram1-4 mutations on gene expression, revealing that the two genes alter the expression of overlapping but not identical gene sets, suggesting that RAM1 acts upstream of KIN3. Additionally, KIN3 appears to be involved in the suppression of plant defences in response to the fungal symbiont. KIN3 is located on the endoplasmic reticulum of arbuscule-containing cortical cells, and kin3-2 mutants plants hosted significantly fewer arbuscules than the wild type. KIN3 plays an essential role in the symbiotic response to soil nitrogen levels, as, contrary to wild-type plants, the kin3-2 mutant did not exhibit increased root colonisation under high nitrogen.

A H+-ATPase That Energizes Nutrient Uptake during Mycorrhizal Symbioses in Rice and Medicago truncatula.

Most plant species form symbioses with arbuscular mycorrhizal (AM) fungi, which facilitate the uptake of mineral nutrients such as phosphate from the soil. Several transporters, particularly proton-coupled phosphate transporters, have been identified on both the plant and fungal membranes and contribute to delivering phosphate from fungi to plants. The mechanism of nutrient exchange has been studied in plants during mycorrhizal colonization, but the source of the electrochemical proton gradient that drives nutrient exchange is not known. Here, we show that plasma membrane H+-ATPases that are specifically induced in arbuscule-containing cells are required for enhanced proton pumping activity in membrane vesicles from AM-colonized roots of rice (Oryza sativa) and Medicago truncatula. Mutation of the H+-ATPases reduced arbuscule size and impaired nutrient uptake by the host plant through the mycorrhizal symbiosis. Overexpression of the H+-ATPase Os-HA1 increased both phosphate uptake and the plasma membrane potential, suggesting that this H+-ATPase plays a key role in energizing the periarbuscular membrane, thereby facilitating nutrient exchange in arbusculated plant cells.

Overexpression of the potassium channel TPKb in small vacuoles confers osmotic and drought tolerance to rice.

Potassium (K(+) ) is the most important cationic nutrient for all living organisms. Vacuolar two-pore K(+) (TPK) channels are important players in the regulation of cellular levels of K(+) but have not been characterised in rice. In order to assess the role of OsTPKb, a K(+) selective ion channel predominantly expressed in the tonoplast of small vacuoles, we generated overexpressing (OX) lines using a constitutive promoter and compared their phenotypes with control plants. Relative to control plants, OX lines showed better growth when exposed to low-K(+) or water stress conditions. K(+) uptake was greater in OX lines which may be driven by increased AKT1 and HAK1 activity. The enhanced K(+) uptake led to tissue K(+) levels that were raised in roots and shoots. Furthermore, energy dispersive X-ray (EDX) analyses showed a higher cytoplasm: vacuole K(+) ratio which is likely to contribute to the increased stress tolerance. In all, the data suggest that TPKb can alter the K(+) status of small vacuoles, which is important for general cellular K(+) homeostasis which, in turn, affects stress tolerance.

Real-World Burden of Immunosuppressant-Treated Lupus Nephritis: A German Claims Database Analysis.

INTRODUCTION: This retrospective cohort study (GSK213737) aimed to characterize treatment patterns, healthcare resource utilization (HCRU), and costs in patients with lupus nephritis (LN) initiating immunosuppressant therapy in clinical practice in Germany, to better understand the full picture of the real-world burden of LN. METHODS: Adult patients with LN who initiated mycophenolate mofetil (MMF), intravenous cyclophosphamide (CYC), azathioprine (AZA), tacrolimus, cyclosporin A, or rituximab therapy in 2011-2017 (index therapy) were identified from the Betriebskrankenkassen German Sickness Fund database. Treatment patterns, including immunosuppressant discontinuations, and therapy switches, were assessed (maximum follow-up 4 years). Corticosteroid use, HCRU, and total economic costs were also evaluated. HCRU and costs were compared with matched controls (individuals without systemic lupus erythematosus [SLE]/LN matched by age, sex, and baseline Charlson Comorbidity Index). RESULTS: Among 334 patients with LN, the median (interquartile range) duration of index immunosuppressant therapy use was 380.5 (126, 1064) days. Of those patients with 4 years complete enrollment, 70.8% had ≥ 1 discontinuation and 28.8% switched therapy. While most patients (71.2%) received only one immunosuppressant, gaps in treatment were common. After 1 year of follow-up, 41.6% of patients had a prednisone-equivalent corticosteroid dose of ≥ 7.5 mg/day. Patients with LN had greater HCRU use for most categories assessed and increased mean total costs per person-year versus controls (€15,115.99 versus €4,081.88 in the first year of follow-up). CONCLUSIONS: This real-world analysis demonstrated the considerable burden of immunosuppressant-treated LN in Germany, with a high rate of discontinuations, frequent use of high-dose corticosteroids, and substantial HCRU/costs.

Clinical and economic burden of organ damage among patients with systemic lupus erythematosus in a real-world setting in Germany.

BACKGROUND: Systemic lupus erythematosus (SLE), a chronic multisystem autoimmune disease, carries high risk of organ damage and burden to healthcare systems. SLE disease modification aims to reduce disease activity with minimal treatment toxicity and preventing or minimizing organ damage development. This real-world study utilizing healthcare administrative claims data assessed organ damage development, associated costs and healthcare resource utilization (HCRU) in patients with SLE in Germany. METHODS: Claims data from January 1, 2007, to December 31, 2017, were obtained from the Betriebskrankenkassen German Sickness Fund Database. Adults (> 18 years) with a confirmed SLE diagnosis between January 1, 2009, and December 31, 2014, (inclusion period) were included. The index date was calculated based on the first recorded SLE diagnosis during this period. Patients were propensity score-matched (1:3) to a comparator cohort without SLE by age, sex, and comorbidities (Charlson comorbidity index). Organ damage was identified using an algorithm developed based on conditions described in the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI), using ICD-10-GM diagnostic codes, healthcare procedures, and/or treatments. RESULTS: 2121 patients with SLE and 6308 comparator patients were included (mean follow-up time: 6.4 years). Organ damage prevalence increased from 60.5% at baseline to 83.0% during 6 years of follow-up in all patients with SLE, while 17.0% of patients with SLE did not develop organ damage. Patients with newly confirmed SLE diagnosis without organ damage at baseline were nearly twice as likely to develop organ damage within 5 years versus the comparator cohort (52.0% vs. 27.0%). Total annual costs per patient-year for patients with SLE with organ damage were more than double those of patients with SLE without organ damage; both the number of inpatient admissions and length of stay were higher. CONCLUSIONS: The application of a recently developed algorithm allowed us to use claims data to elucidate SLE organ damage, and its associated high clinical and economic burden, in a large, representative sample in Germany. To our knowledge, this is the first European analysis of its kind involving a broad cohort of patients with SLE treated in the routine care setting.

Treatment Patterns and Adherence to Guidelines for Uncomplicated Urinary Tract Infection in Germany: A Retrospective Cohort Study.

INTRODUCTION: Understanding antibiotic prescribing for uncomplicated urinary tract infection (uUTI) could help to optimize management. However, data on uUTI treatment patterns in the European Union are scarce. We used real-world data to evaluate adherence to antibiotic prescribing guidelines for femalepatients with uUTI in Germany. METHODS: This retrospective cohort study used anonymized German statutory health insurance claims data from the Wissenschaftliches Institut für Gesundheitsökonomie und Gesundheitssystemforschung from January 2013 to December 2019. Patients were female, aged ≥ 12 years, with an index uUTI diagnosis. Patient characteristics and treating physician specialties were examined overall and in sub-cohorts for recommended/non-recommended treatment (based on initial therapy adherence to German uUTI treatment guidelines) and optimal/sub-optimal outcome (based on a prescription of different antibiotics or a urinary tract infection-related episode). RESULTS: Overall, 144,645 uUTI cases in 124,971 patients were analyzed; 51,230 (35.4%) and 93,415 (64.6%) cases were assigned to the recommended/non-recommended treatment sub-cohorts, respectively. Clinically meaningful differences in age and comorbidities were observed between these sub-cohorts. Most cases had an optimal outcome (n = 122,823; 84.9%); of these, a higher proportion received antibiotics that were recommended but not as first-choice versus first-choice therapies as their initial treatment (58.6% vs. 35.3%). In the sub-optimal outcome cohort, 49.1% received antibiotics that were recommended but not as first-choice and 41.1% received first-choice therapies as their initial treatment. Most uUTIs were treated by general practitioners (GPs; 82.3%), followed by gynecologists (13.3%), and urologists (6.8%). Notably, 64.5% of initial therapy prescriptions filled by gynecologists and 32.1% by GPs were first-choice antibiotics. CONCLUSION: A high proportion of prescribed treatments for the initial uUTI episode were not recommended by German uUTI guidelines as first-choice antibiotics. Prescribing adherence varied by physician specialty; specialists showed greater adherence to treatment guidelines versus GPs. This study provides a novel and multi-dimensional picture of uUTI treatment in Germany.

Uncomplicated urinary tract infections are one of the most common infections in women. Doctors around the world use different types of antibiotics to treat people with uncomplicated urinary tract infections. We performed this study to find out more about how doctors in Germany use antibiotics to treat uncomplicated urinary tract infections. We looked at health records from female patients (aged 12+) in Germany. Overall, we examined 144,645 records. We found that around one in ten women use antibiotics to treat an uncomplicated urinary tract infection every year. We then checked to see if the doctors were giving people the right type of antibiotic, the right dose, and the right length of course. To do this, we checked against guidelines that were written by experts in Germany. We found that only one in three patients (35%) received treatment that met the guidelines. We also looked to see what differences there were between different types of doctors. For example, if general practitioners (family doctors) used different antibiotics to specialist doctors in hospitals. Four out of five patients (82%) were treated by general practitioners. We found that specialists were more likely to stick to the guidelines than general practitioners. Finally, we looked at how many patients recovered well after their first course of antibiotics. More than four out of five patients (80%) recovered well. Interestingly, more than half of the patients who had a good recovery (59%) received antibiotics that were not recommended by the guidelines.

Vapyrin, a gene essential for intracellular progression of arbuscular mycorrhizal symbiosis, is also essential for infection by rhizobia in the nodule symbiosis of Medicago truncatula.

Intracellular invasion of root cells is required for the establishment of successful endosymbioses in legumes of both arbuscular mycorrhizal (AM) fungi and rhizobial bacteria. In both interactions a requirement for successful entry is the activation of a common signalling pathway that includes five genes required to generate calcium oscillations and two genes required for the perception of the calcium response. Recently, it has been discovered that in Medicago truncatula, the Vapyrin (VPY) gene is essential for the establishment of the arbuscular mycorrhizal symbiosis. Here, we show by analyses of mutants that the same gene is also required for rhizobial colonization and nodulation. VPY encodes a protein featuring a Major Sperm Protein domain, typically featured on proteins involved in membrane trafficking and biogenesis, and a series of ankyrin repeats. Plants mutated in this gene have abnormal rhizobial infection threads and fewer nodules, and in the case of interactions with AM fungi, epidermal penetration defects and aborted arbuscule formation. Calcium spiking in root hairs in response to supplied Nod factors is intact in the vpy-1 mutant. This, and the elevation of VPY transcripts upon application of Nod factors which we show to be dependent on NFP, DMI1, and DMI3, indicates that VPY acts downstream of the common signalling pathway.

Stimulation of serum- and glucocorticoid-regulated kinase-1 gene expression by endothelin-1.

The serum- and glucocorticoid-regulated kinase-1 (SGK1) participates in the regulation of sodium homeostasis and blood pressure by mineralocorticoids. Aldosterone rapidly induces SGK1 transcription, which contributes to the activation of renal epithelial sodium channels. Another important regulator of blood pressure is the vasoactive hormone endothelin-1 (ET-1) that is systemically upregulated in chronic renal failure. In the present study, we investigated whether ET-1 modulates SGK1 expression, and thereby might explain some of its hypertensive effects. As assessed by real-time PCR analysis, ET-1 triggered the rapid increase of SGK1 mRNA levels in A-10 smooth muscle cells and also in intact aortas of adult rats. In A-10 cells transcriptional activation was associated with a more than 6-fold upregulation of SGK1 protein expression and in similar range as found after treatment with aldosterone. A stimulatory effect of ET-1 was not only observed in isolated cells, but also in an animal model. Upon subtotal nephrectomy (SNX) of rats, myocardial ET-1 levels strongly increased, which was followed by a more than 2-fold induction of SGK1 expression in the left ventricle. The myocardial upregulation of SGK1 was completely abrogated by a specific ET(A) receptor antagonist, thereby substantiating the in vivo role of ET-1 in SGK1 expression. Thus, these data demonstrate that ET-1 increases expression of SGK1 in vivo and in vitro, and therefore indicate that SGK1 upregulation might be involved in ET-1-dependent regulation of blood pressure and cardiac modelling during mild renal failure.

Endothelin-1 increases serum-glucocorticoid-regulated kinase-1 expression in smooth muscle cells.

The mechanism of salt-sensitive hypertension is not fully understood. Several studies point to a possible role of endothelin (ET)-1 in this form of hypertension. Serum-regulated and glucocorticoid-regulated kinase-1 (SGK1) mediates trafficking of the renal epithelial sodium channel. The aim of the study was to find out whether ET-1 regulates SGK1. Rat smooth muscle cells were incubated with ET-1 (10(-7) M, 0-120 minutes). After 30 minutes a significant increase in SGK1 mRNA was found (122 +/- 4.2%), and a maximum was reached after 120 minutes (217 +/- 7.6%). Incubation of smooth muscle cells with ET-1 (10(-7) mol/L) in the presence of an ETA receptor antagonist inhibited SGK1 gene transcription (93 +/- 3.7%). Western blot analysis showed a time-dependent increase in SGK1 protein in smooth muscle cells. These data indicate that ET-1 increases SKG1 mRNA and protein concentration. Inhibition of ET-1 by ET antagonism prevented a SGK1 increase. Therefore, ET antagonism might influence blood pressure by regulating the sodium balance through reducing SGK1 gene expression.

Protocols for growing plant symbioses; mycorrhiza.

Arbuscular mycorrhizal symbiosis is receiving increased attention as a potential contributor to sustainable crop plant nutrition. This chapter details a set of protocols for plant growth to study the development and physiology of the arbuscular mycorrhizal symbiosis, and how to establish root organ cultures for the production of axenic inoculum.

RAM1 and RAM2 function and expression during arbuscular mycorrhizal symbiosis and Aphanomyces euteiches colonization.

The establishment of the symbiotic interaction between plants and arbuscular mycorrhizal (AM) fungi requires a very tight molecular dialogue. Most of the known plant genes necessary for this process are also required for nodulation in legume plants and only very recently genes specifically required for AM symbiosis have been described. Among them we identified RAM (Reduced Arbuscular Mycorrhization)1 and RAM2, a GRAS transcription factor and a GPAT respectively, which are critical for the induction of hyphopodia formation in AM fungi. RAM2 function is also required for appressoria formation by the pathogen Phytophtora palmivora. Here we investigated the activity of RAM1 and RAM2 promoters during mycorrhization and the role of RAM1 and RAM2 during infection by the root pathogen Aphanomyces euteiches. pRAM1 is activated without cell type specificity before hyphopodia formation, while pRAM2 is specifically active in arbusculated cells providing evidence for a potential function of cutin momomers in the regulation of arbuscule formation. Furthermore, consistent with what we observed with Phytophtora, RAM2 but not RAM 1 is required during Aphanomyces euteiches infection.

A common signaling process that promotes mycorrhizal and oomycete colonization of plants.

The symbiotic association between plants and arbuscular mycorrhizal fungi is almost ubiquitous within the plant kingdom, and the early stages of the association are controlled by plant-derived strigolactones acting as a signal to the fungus in the rhizosphere and lipochito-oligosaccharides acting as fungal signals to the plant. Hyphopodia form at the root surface, allowing the initial invasion, and this is analogous to appressoria, infection structures of pathogenic fungi and oomycetes. Here, we characterize RAM2, a gene of Medicago truncatula required for colonization of the root by mycorrhizal fungi, which is necessary for appropriate hyphopodia and arbuscule formation. RAM2 encodes a glycerol-3-phosphate acyl transferase (GPAT) and is involved in the production of cutin monomers. Plants defective in RAM2 are unable to be colonized by arbuscular mycorrhizal fungi but also show defects in colonization by an oomycete pathogen, with the absence of appressoria formation. RAM2 defines a direct signaling function, because exogenous addition of the C16 aliphatic fatty acids associated with cutin are sufficient to promote hyphopodia/appressoria formation. Thus, cutin monomers act as plant signals that promote colonization by arbuscular mycorrhizal fungi, and this signaling function has been recruited by pathogenic oomycetes to facilitate their own invasion.

A GRAS-type transcription factor with a specific function in mycorrhizal signaling.

Legumes establish mutualistic associations with mycorrhizal fungi and with nitrogen-fixing rhizobial bacteria. These interactions occur following plant recognition of Nod factor from rhizobial bacteria and Myc factor from mycorrhizal fungi. A common symbiosis signaling pathway is involved in the recognition of both Nod factor and Myc factor and is required for the establishment of these two symbioses. The outcomes of these associations differ, and therefore, despite the commonality in signaling, there must be mechanisms that allow specificity. In Nod factor signaling, a complex of GRAS-domain transcription factors controls gene expression downstream of the symbiosis signaling pathway. Here, we show that a GRAS-domain transcription factor, RAM1, functions in mycorrhizal-specific signaling. Plants mutated in RAM1 are unable to be colonized by mycorrhizal fungi, with a defect in hyphopodia formation on the surface of the root. RAM1 is specifically required for Myc factor signaling and appears to have no role in Nod factor signaling. RAM1 regulates the expression of RAM2, a glycerol-3-phosphate acyl transferase that promotes cutin biosynthesis to enhance hyphopodia formation. We conclude that mycorrhizal signaling downstream of the symbiosis-signaling pathway has parallels with nodulation-specific signaling and functions to promote mycorrhizal colonization by regulating cutin biosynthesis.

Circadian plasticity in photoreceptor cells controls visual coding efficiency in Drosophila melanogaster.

In the fly Drosophila melanogaster, neuronal plasticity of synaptic terminals in the first optic neuropil, or lamina, depends on early visual experience within a critical period after eclosion. The current study revealed two additional and parallel mechanisms involved in this type of synaptic terminal plasticity. First, an endogenous circadian rhythm causes daily oscillations in the volume of photoreceptor cell terminals. Second, daily visual experience precisely modulates the circadian time course and amplitude of the volume oscillations that the photoreceptor-cell terminals undergo. Both mechanisms are separable in their molecular basis. We suggest that the described neuronal plasticity in Drosophila ensures continuous optimal performance of the visual system over the course of a 24 h-day. Moreover, the sensory system of Drosophila cannot only account for predictable, but also for acute, environmental changes. The volumetric changes in the synaptic terminals of photoreceptor cells are accompanied by circadian and light-induced changes of presynaptic ribbons as well as extensions of epithelial glial cells into the photoreceptor terminals, suggesting that the architecture of the lamina is altered by both visual exposure and the circadian clock. Clock-mutant analysis and the rescue of PER protein rhythmicity exclusively in all R1-6 cells revealed that photoreceptor-cell plasticity is autonomous and sufficient to control visual behavior. The strength of a visually guided behavior, the optomotor turning response, co-varies with synaptic-terminal volume oscillations of photoreceptor cells when elicited at low light levels. Our results show that behaviorally relevant adaptive processing of visual information is performed, in part, at the level of visual input level.

Molecular cloning of a bifunctional beta-xylosidase/alpha-L-arabinosidase from alfalfa roots: heterologous expression in Medicago truncatula and substrate specificity of the purified enzyme.

Glycoside hydrolases are often members of a multigene family, suggesting individual roles for each isoenzyme. Various extracellular glycoside hydrolases have an important but poorly understood function in remodelling the cell wall during plant growth. Here, MsXyl1, a concanavalin A-binding protein from alfalfa (Medicago sativa L.) belonging to the glycoside hydrolase family 3 (beta-D-xylosidase branch) is characterized. Transcripts of MsXyl1 were detected in roots (particularly root tips), root nodules, and flowers. MsXyl1 under the control of the CaMV 35S promoter was expressed in the model legume Medicago truncatula (Gaertner). Concanavalin A-binding proteins from the transgenic plants exhibited 5-8-fold increased activities towards three p-nitrophenyl (PNP) glycosides, namely PNP-beta-D-xyloside, PNP-alpha-L-arabinofuranoside, and PNP-alpha-L-arabinopyranoside. An antiserum raised against a synthetic peptide recognized MsXyl1, which was processed to a 65 kDa form. To characterize the substrate specificity of MsXyl1, the recombinant protein was purified from transgenic M. truncatula leaves by concanavalin A and anion chromatography. MsXyl1cleaved beta-1,4-linked D-xylo-oligosaccharides and alpha-1,5-linked L-arabino-oligosaccharides. Arabinoxylan (from wheat) and arabinan (from sugar beet) were substrates for MsXyl1, whereas xylan (from oat spelts) was resistant to degradation. Furthermore, MsXyl1 released xylose and arabinose from cell wall polysaccharides isolated from alfalfa roots. These data suggest that MsXyl1 is a multifunctional beta-xylosidase/alpha-L-arabinofuranosidase/alpha-L-arabinopyranosidase implicated in cell wall turnover of arabinose and xylose, particularly in rapidly growing root tips. Moreover, the findings of this study demonstrate that stable transgenic M. truncatula plants serve as an excellent expression system for purification and characterization of proteins.

Medicago truncatula NIN is essential for rhizobial-independent nodule organogenesis induced by autoactive calcium/calmodulin-dependent protein kinase.

The symbiotic association between legumes and nitrogen-fixing bacteria collectively known as rhizobia results in the formation of a unique plant root organ called the nodule. This process is initiated following the perception of rhizobial nodulation factors by the host plant. Nod factor (NF)-stimulated plant responses, including nodulation-specific gene expression, is mediated by the NF signaling pathway. Plant mutants in this pathway are unable to nodulate. We describe here the cloning and characterization of two mutant alleles of the Medicago truncatula ortholog of the Lotus japonicus and pea (Pisum sativum) NIN gene. The Mtnin mutants undergo excessive root hair curling but are impaired in infection and fail to form nodules following inoculation with Sinorhizobium meliloti. Our investigation of early NF-induced gene expression using the reporter fusion ENOD11::GUS in the Mtnin-1 mutant demonstrates that MtNIN is not essential for early NF signaling but may negatively regulate the spatial pattern of ENOD11 expression. It was recently shown that an autoactive form of a nodulation-specific calcium/calmodulin-dependent protein kinase is sufficient to induce nodule organogenesis in the absence of rhizobia. We show here that MtNIN is essential for autoactive calcium/calmodulin-dependent protein kinase-induced nodule organogenesis. The non-nodulating hcl mutant has a similar phenotype to Mtnin, but we demonstrate that HCL is not required in this process. Based on our data, we suggest that MtNIN functions downstream of the early NF signaling pathway to coordinate and regulate the correct temporal and spatial formation of root nodules.