Characterization of PHO1 and PHO1;H1 gene function in Arabidopsis thaliana

Summary Phosphorus is one of the major macronutrients required for plant growth and development. Plant roots acquire phosphorus as inorganic phosphate (Pi), which is further distributed to the shoot, via the transpiration stream and root pressure, where Pi is imported again into cells. PHO1 in Arabidopsis has been identified as a protein involved in the loading of Pi into the root xylem. PHO1 does not have any homology to described Pi transporters including the Pht1 family of H+/ Pi cotransporters. PHO1 bears two domains, SPX and EXS domains, previously identified in Saccharomyces cerevisiae proteins involved in Pi transport and/or sensing, or in sorting proteins to endomembranes. Phylogenetic analysis of the PHO1 gene family revealed the presence of three clusters, with PHO1 and PHO1;H1 forming one cluster. The biological significance behind this cluster was demonstrated by the complementation of the pho1 mutant with only PHO1 and PHO1;H1, of all the PHO1 family members, when expressed under the PHO1 promoter. PHO1 has been shown to be expressed mostly in the root vascular cylinder and at low level in the shoot. PHO1;H1 had a different expression pattern, being expressed in both root and shoot vascular cylinder to the same level, with the levels in leaves increasing with the leaf maturity, suggesting additional role of PHO1;H1 in the Pi mobilization in leaves. In order to further explore the role of PHO1, Pi dynamics was studied on plants expressing PHO1 at different levels compared to the wild type: PHO1 overexpressors, PHO1 underexpressors and the pho1 mutant. Overexpression of the PHO1 protein in the shoot vascular tissue was shown to lead to increased Pi efflux out of the leaf cells and Pi accumulation in the shoot xylem apoplast compared to wild type, confirming the hypothesized role of PHO1 in xylem loading with Pi. The overexpression of PHO1 in the shoot was responsible far both changed Pi dynamic and stunted growth of PHO1 overexpressors, as shown by grafting experiments between wild type and PHO1 overexpressor. We found a ca. 2 fold decrease of shoot phosphorus and a 5-10 fold decrease in vacuolar Pi content in the PHO1 underexpressors and the pho1 null mutant compared to wild type, consistent with the role of PHO1 in the transfer of Pi from the root to the shoot. Shoot Pi deficiency results in a poor growth of the pho1 mutant. Grafting experiments between pho1 and wild type confirmed that both Pi deficiency and stunt growth of the pho1 mutant were dependent on the pho1 root, further supporting the importance of PHO1 in the root xylem loading with Pi. The pho1 mutant and the PHO1 underexpressors accumulated 8-15 fold more Pi in the root relative to wild type. In contrast to the pho1 mutant, the growth of PHO1 underexpressors was not impaired by the low shoat Pi content. This finding suggests that either PHO1 protein or root Pi concentration is important in Pi signaling and development of Pi deficiency symptoms leading to reduced growth. Résumé Le phosphore est l'un des nutriments essentiels à la croissance et au développement des plantes. Les racines absorbent le phosphore sous forme de phosphate inorganique (Pi) qui est dirigé, par la transpiration et la pression de la racine, vers les feuilles où le phosphate est acquis par les cellules. La protéine PHO1 a été démontrée indispensable au chargement du Pi dans le xylème des racines d'Arabidopsis. PHO1 ne démontre pas d'homologie aux transporteurs de Pi connus, incluant la famille Pht1 de cotransporteurs H+/Pi qui ont comme fonction le transport du phosphate à l'intérieur de la cellule. PHO1 contient deux domaines, SPX et EXS, aussi présents dans des protéines de Saccharomyces cerevisiae impliquées dans le transport ou la perception du phosphate, ou dans la localisation des protéines vers différentes membranes. Le génome d'Arabidopsis contient onze gènes homologues à PHO1. Neuf de ces homologues sont répartis en trois groupes. PHO1 et PHO1;H1 forment un de ces groupes. Nos travaux ont démontré que seuls PHO1;H1 et PHO1, sous contrôle du promoteur PHO1, peuvent complémenter le mutant pho1. PHO1 est exprimé principalement dans le cylindre vasculaire de la racine et faiblement dans la partie aérienne. Le degré d'expression de PHO1;H1 est similaire dans le cylindre vasculaire de la racine et des feuilles. Ceci suggère que PHO1;H1 est aussi impliqué dans la mobilisation du Pi dans les feuilles, en plus de son rôle dans le transfert du Pi dans le xylème des racines. Afin de mieux explorer le rôle de PHO1, la dynamique du phosphate a été observée dans trois lignées de plantes transgéniques: un sur-expresseur de PHO1, un sous-expresseur de PHO1 et le mutant pho1. La sur-expression de PHO1 dans le tissue vasculaire des feuilles a provoqué l'efflux du Pi vers l'espace apoplastic du xylème, ce qui confirme le rôle de PHO1 dans le chargement du Pi dans le xylème. La sur-expressìon de PHO1 dans la rosette est responsable d'un changement de la dynamique du Pi et de la diminution de la croissance, ce qui fut démontré par une expérience de greffe de la rosette du sur-expresseur de PHO1 sur les racines du sauvage. On a observé pour le sous-expresseur de PHO1 et le mutant pho1 une diminution du phosphore d'environ 2 fais au niveau des feuilles, et une diminution de 5-10 fois du Pi dans les vacuoles des feuilles, par rapport au sauvage. Ceci confirme le rôle proposé de PHO1 dans le transfert du Pi des racines aux feuilles. La carence de Pi chez pho1 implique une diminution de la taille de la rosette. Pour expliquer ce phénotype une autre expérience de greffe démontra que la cause de ce changement provenait des racines. Ceci renforce l'hypothèse de l'importance du rôle de PHO1 dans le xylème de la racine pour le chargement du Pi. Le mutant phot et le sous-expresseur de PHO1 accumulent 8-15 fois plus de Pi dans leurs racines comparé au sauvage. Cependant, contrairement au phot mutant, le sous-expresseur de PHO1 avait une croissance comparable au sauvage malgré le niveau bas du Pi dans les feuilles. Ceci suggère que la taille de la rosette lors d'une carence en Pi chez Arabidopsis serait la conséquence d'un changement de concentration de Pi dans les racines ou d'une influence de la protéine PHO1.

Patient versus general practitioner perception of problems with treatment adherence in type 2 diabetes: from adherence to concordance.

OBJECTIVES: To determine the prevalence of problems with treatment adherence among type-2 diabetic patients with regards to medication, dietary advice, and physical activity; to identify the associated clinical and psychosocial factors; and to investigate the degree of agreement between patient-perceived and GP-perceived adherence. METHODS: Consecutive patients were solicited during visits to 39 GPs. In total, 521 patients self-reported on treatment adherence, anxiety and depression, and disease perception. The GPs reported clinical and laboratory data and patients' adherence. A multivariate analysis identified the factors associated with adherence problems. RESULTS: Problems of adherence to medication, dietary advice, and physical activity recommendations were reported by 17%, 62%, and 47% of the patients, respectively. Six independent factors were found associated with adherence problems: young age, body-mass index (BMI) > 30 kg/m(2), glycosylated haemoglobin (HbA(1c)) > 8%, single life, depression, and perception of medication as a constraint. Agreement between patients' and GPs' assessments of treatment problems reached 70%. CONCLUSION: In type 2 diabetes, problems with dietary advice or physical activity are far more frequent than problems with medication, and not all physicians are fully aware of patients' problems. More active listening and shared decision-making should enhance adherence and improve outcomes.

Recovery of biological motion perception and network plasticity after cerebellar tumor removal.

Visual perception of body motion is vital for everyday activities such as social interaction, motor learning or car driving. Tumors to the left lateral cerebellum impair visual perception of body motion. However, compensatory potential after cerebellar damage and underlying neural mechanisms remain unknown. In the present study, visual sensitivity to point-light body motion was psychophysically assessed in patient SL with dysplastic gangliocytoma (Lhermitte-Duclos disease) to the left cerebellum before and after neurosurgery, and in a group of healthy matched controls. Brain activity during processing of body motion was assessed by functional magnetic resonance imaging (MRI). Alterations in underlying cerebro-cerebellar circuitry were studied by psychophysiological interaction (PPI) analysis. Visual sensitivity to body motion in patient SL before neurosurgery was substantially lower than in controls, with significant improvement after neurosurgery. Functional MRI in patient SL revealed a similar pattern of cerebellar activation during biological motion processing as in healthy participants, but located more medially, in the left cerebellar lobules III and IX. As in normalcy, PPI analysis showed cerebellar communication with a region in the superior temporal sulcus, but located more anteriorly. The findings demonstrate a potential for recovery of visual body motion processing after cerebellar damage, likely mediated by topographic shifts within the corresponding cerebro-cerebellar circuitry induced by cerebellar reorganization. The outcome is of importance for further understanding of cerebellar plasticity and neural circuits underpinning visual social cognition.

Heat perception and signalling in plants: a tortuous path to thermotolerance.

An accurate assessment of the rising ambient temperature by plant cells is crucial for the timely activation of various molecular defences before the appearance of heat damage. Recent findings have allowed a better understanding of the early cellular events that take place at the beginning of mild temperature rise, to timely express heat-shock proteins (HSPs), which will, in turn, confer thermotolerance to the plant. Here, we discuss the key components of the heat signalling pathway and suggest a model in which a primary sensory role is carried out by the plasma membrane and various secondary messengers, such as Ca(2+) ions, nitric oxide (NO) and hydrogen peroxide (H(2) O(2) ). We also describe the role of downstream components, such as calmodulins, mitogen-activated protein kinases and Hsp90, in the activation of heat-shock transcription factors (HSFs). The data gathered for land plants suggest that, following temperature elevation, the heat signal is probably transduced by several pathways that will, however, coalesce into the final activation of HSFs, the expression of HSPs and the onset of cellular thermotolerance.

Physicians' estimates of the 10-year cardiovascular risk in hypertensive patients

RESUME L'objectif de cette étude est d'évaluer comment de jeunes médecins en formation perçoivent le risque cardiovasculaire de leurs patients hypertendus en se basant sur les recommandations médicales (« guidelines ») et sur leur jugement clinique. Il s'agit d'une étude transversale observationnelle effectuée à la Policlinique Médicale Universitaire de Lausanne (PMU). 200 patients hypertendus ont été inclus dans l'étude ainsi qu'un groupe contrôle de 50 patients non hypertendus présentant au moins un facteur de risque cardiovasculaire. Nous avons comparé le risque cardiovasculaire à 10 ans calculé par un programme informatique basé sur l'équation de Framingham. L'équation a été adaptée pour les médecins par l'OMS-ISH au risque perçu, estimé cliniquement par les médecins. Les résultats de notre étude ont montrés que les médecins sous-estiment le risque cardiovasculaire à 10 ans de leurs patients, comparé au risque calculé selon l'équation de Framingham. La concordance entre les deux méthodes était de 39% pour les patients hypertendus et de 30% pour le groupe contrôle de patients non hypertendus. La sous-estimation du risque. cardiovasculaire pour les patients hypertendus était corrélée au fait qu'ils avaient une tension artérielle systolique stabilisée inférieure a 140 mmHg (OR=2.1 [1.1 ;4.1]). En conclusion, les résultats de cette étude montrent que les jeunes médecins en formation ont souvent une perception incorrecte du risque cardiovasculaire de leurs patients, avec une tendance à sous-estimer ce risque. Toutefois le risque calculé pourrait aussi être légèrement surestimé lorsqu'on applique l'équation de Framingham à la population suisse. Pour mettre en pratique une évaluation systématique des facteurs de risque en médecine de premier recours, un accent plus grand devrait être mis sur l'enseignement de l'évaluation du risque cardiovasculaire ainsi que sur la mise en oeuvre de programme pour l'amélioration de la qualité.

Contrôle glycémique du diabète de type 2: intensif ou classique ?: revue Cochrane pour le praticien

Cet article présente les résultats de la revue systématique: Hemmingsen B, Lund SS, Gluud C, Vaag A, Almdal T, Hemmingsen C, Wetterslev J. Targeting intensive glycaemic control versus targeting conventional glycaemic control for type 2 diabetes mellitus. Cochrane Database of Systematic Reviews 2011 Jun 15;(6):CD008143. DOI: 10.1002/14651858.CD008143.pub2. PMID: 21678374.

Risk perception and emotional coping: a pathway for behavioural addiction?

This article summarizes current concepts of the working memory with regard to its role within emotional coping strategies. In particular, it focuses on the fact that the limited capacity of the working memory to process now-relevant information can be turned into an advantage, when the individual is occupied by dealing with unpleasant emotion. Based on a phenomenon known as dual-task interference (DTI), this emotion can be chased by intense arousal due to clearly identifiable external stressors. Thus, risk perception might be used as a 'DTI inductor' that allows avoidance of unpleasant emotion. Successful mastery of risk adds a highly relevant dopaminergic component to the overall experience. The resulting mechanism of implicit learning may contribute to the development of a behavioural addiction. Besides its putative effects in the development of a behavioural addiction, the use of DTI might be of a more general interest for the clinical practice, especially in the field of psychotherapy. © 2013 S. Karger AG, Basel.

Context- and Prosody-Driven ERP Markers for Dialog Focus Perception in Children.

The development of language proficiency extends late into childhood and includes not only producing or comprehending sounds, words and sentences, but likewise larger utterances spanning beyond sentence borders like dialogs. Dialogs consist of information units whose value constantly varies within a verbal exchange. While information is focused when introduced for the first time or corrected in order to alter the knowledge state of communication partners, the same information turns into shared knowledge during the further course of a verbal exchange. In many languages, prosodic means are used by speakers to highlight the informational value of information foci. Our study investigated the developmental pattern of event-related potentials (ERPs) in three age groups (12, 8 and 5 years) when perceiving two information focus types (news and corrections) embedded in short question-answer dialogs. The information foci contained in the answer sentences were either adequately marked by prosodic means or not. In so doing, we questioned to what extent children depend on prosodic means to recognize information foci or whether contextual means as provided by dialog questions are sufficient to guide focus processing.Only 12-year-olds yield prosody-independent ERPs when encountering new and corrective information foci, resembling previous findings in adults. Focus processing in the 8-year-olds relied upon prosodic highlighting, and differing ERP responses as a function of focus type were observed. In the 5-year-olds, merely prosody-driven ERP responses were apparent, but no distinctive ERP indicating information focus recognition. Our findings reveal substantial alterations in information focus perception throughout childhood that are likely related to long-lasting maturational changes during brain development.