Mechanism of HFR1 function in adaptive growth responses in "Arabidopsis thaliana"

AbstractPlants are sessile organisms, which have evolved an astonishing ability to sense changes in their environment. Depending on the surrounding conditions, such as changes in light and temperature, plants modulate the activity of important transcriptional regulators. The shade avoidance syndrome (SAS) is one important mechanism for shade-intolerant plants to adapt their growth in high vegetative density. In shaded conditions plants sense a diminished red/far-red ratio via the phytochrome system and respond with morphological changes such as elongation growth of stems and petioles. The Phytochrome Interacting Factors 4 and 5 (PIF4 and PIF5) are positive regulators of the SAS and required for a full response (Lorrain et al, 2008). They regulate the SAS by inducing the expression of shade avoidance marker genes such as PIL1, ATHB2, XTR7 and HFR1 (Hornitschek et al, 2009; Lorrain et al, 2008).I investigated the molecular mechanism underlying the regulation of the SAS by HFR1 (long Hypocotyl in FR light). Although HFR1 is a PIF-related bHLH transcription factor, we discovered that HFR1 is a non-DNA binding protein. Moreover, we revealed that HFR1 inhibits an exaggerated SAS by forming non-DNA binding heterodimers with PIF4 and PIF5 (Hornitschek et al, 2009). This negative feedback loop is an important mechanism to limit elongation growth also in elevated temperatures. HFR1 accumulation and activity are highly temperature-dependent and the increased activity of HFR1 at warmer temperatures also provides an important restraint on PIF4-driven elongation growth (Foreman et al, 2011).Finally we performed a genome-wide analysis to determine how PIF4 and PIF5 regulate growth in response to shade. We identified potential PIF5- target genes, which represent many well-known shade-responsive genes. Our analysis of gene expression also revealed a role of PIF4 and PIF5 in simulated sun possibly via the regulation of auxin sensitivity.RésuméLes plantes sont des organismes sessiles ayant développé une capacité surprenante à détecter des changements dans leur environnement. En fonction des conditions extérieures, telles que les variations de lumière ou de température, elles adaptent l'activité d'importants régulateurs transcriptionnels. Le syndrome d'évitement de l'ombre (SAS), est un mécanisme important pour les plantes intolérantes à l'ombre leur permettant d'adapter leur croissance lorsqu'elles se développent dans des conditions de végétations très denses. Dans ces conditions, les plantes détectent une réduction de la quantité relative de lumière rouge par rapport à la lumière rouge-lointain (rapport R/FR). Ce changement, perçu via le système des phytochromes, induit des modifications morphologiques telle qu'une élongation des tiges et des pétioles. Les protéines PIF4 et PIF5 (Phytochrome Interacting Factors) sont des régulateurs positifs du SAS et sont nécessaires pour une réponse complète (Lorrain et al, 2008). Ces facteurs de transcription régulent le SAS en induisant l'expression de gènes marqueurs de cette réponse tels que PIL1, ATHB2, XTR7 et HFR1 (Hornitschek et al, 2009; Lorrain et al, 2008).J'ai étudié les mécanismes moléculaires sous-jacents à la régulation du SAS par HFR1 (long Hypocotyl in FR light). HFR1 est un facteur de transcription type bHLH de la famille des PIF, quoique nous ayons découvert que HFR1 est une protéine ne se liant pas à Γ ADN. Nous avons montré que HFR1 inhibe un SAS exagéré en formant des heterodimères avec PIF4 et PIF5 (Hornitschek et al, 2009). Nous avons également montré que cette boucle de régulation négative est également un mécanisme important pour limiter la croissance de l'élongation dans des conditions de fortes températures. De plus l'accumulation et l'activité de HFR1 augmentent avec la température ce qui permet d'inhiber plus fortement l'effet activateur de PIF4 sur la croissance.Enfin, nous avons effectué une analyse génomique à large échelle afin de déterminer comment PIF4 et PIF5 régulent la croissance en réponse à l'ombre. Nous avons identifié les gènes cibles potentiels de PIF5, correspondant en partie à des gènes connus dans la réponse de l'évitement de l'ombre. Notre analyse de l'expression des gènes a également révélé un rôle important de PIF4 et PIF5 dans des conditions de croissance en plein soleil, probablement via la régulation de la sensibilité à l'auxine.

Adaptive statistical iterative reconstruction reduces patient radiation dose in neuroradiology CT studies.

INTRODUCTION: Adaptive statistical iterative reconstruction (ASIR) can decrease image noise, thereby generating CT images of comparable diagnostic quality with less radiation. The purpose of this study is to quantify the effect of systematic use of ASIR versus filtered back projection (FBP) for neuroradiology CT protocols on patients' radiation dose and image quality. METHODS: We evaluated the effect of ASIR on six types of neuroradiologic CT studies: adult and pediatric unenhanced head CT, adult cervical spine CT, adult cervical and intracranial CT angiography, adult soft tissue neck CT with contrast, and adult lumbar spine CT. For each type of CT study, two groups of 100 consecutive studies were retrospectively reviewed: 100 studies performed with FBP and 100 studies performed with ASIR/FBP blending factor of 40 %/60 % with appropriate noise indices. The weighted volume CT dose index (CTDIvol), dose-length product (DLP) and noise were recorded. Each study was also reviewed for image quality by two reviewers. Continuous and categorical variables were compared by t test and free permutation test, respectively. RESULTS: For adult unenhanced brain CT, CT cervical myelography, cervical and intracranial CT angiography and lumbar spine CT both CTDIvol and DLP were lowered by up to 10.9 % (p < 0.001), 17.9 % (p = 0.005), 20.9 % (p < 0.001), and 21.7 % (p = 0.001), respectively, by using ASIR compared with FBP alone. Image quality and noise were similar for both FBP and ASIR. CONCLUSION: We recommend routine use of iterative reconstruction for neuroradiology CT examinations because this approach affords a significant dose reduction while preserving image quality.

Active Contour-Based Segmentation of Head and Neck with Adaptive Atlas Selection

This paper presents automated segmentation of structuresin the Head and Neck (H\&N) region, using an activecontour-based joint registration and segmentation model.A new atlas selection strategy is also used. Segmentationis performed based on the dense deformation fieldcomputed from the registration of selected structures inthe atlas image that have distinct boundaries, onto thepatient's image. This approach results in robustsegmentation of the structures of interest, even in thepresence of tumors, or anatomical differences between theatlas and the patient image. For each patient, an atlasimage is selected from the available atlas-database,based on the similarity metric value, computed afterperforming an affine registration between each image inthe atlas-database and the patient's image. Unlike manyof the previous approaches in the literature, thesimilarity metric is not computed over the entire imageregion; rather, it is computed only in the regions ofsoft tissue structures to be segmented. Qualitative andquantitative evaluation of the results is presented.

Insights from insects about adaptive social information use.

Copying others can greatly improve individual fitness and is fundamental for the organisation of societies. Yet in some situations it is better to ignore social information and either explore the world individually or use personal information obtained through prior experience. Insects provide excellent models to study the strategic use of social information, but insights from recent research have rarely been viewed in the light of social learning strategies. Here we discuss how insects tailor their reliance on social information to those circumstances for which it is most beneficial, and suggest that insects and vertebrates use similar information-use strategies. We highlight future research avenues, including the use of molecular tools to study the genetic and genomic basis of social information use.

Evaluation of reclamation technologies for wastewater reuse

Reclamation and reuse of wastewater require the use of tools that minimize risks to health and natural ecosystems. There are various types of such tools, among which HACCP (hazardanalysis and critical control points) and barrier systems are gainingimportance. The research reported here aims to determine andevaluate the most efficient combinations of different treatmentsystems—barriers—for the reclamation of secondary effluentsfrom urban sewage treatment plants, and for obtaining water ofsufficient quality for reuse in accordance with existing legislation,in which water disinfection has become one of the keys tocompliance. Several conventional and non-conventional reclamationtechnologies are evaluated. The results lead us to recommendtreatment lines for the different reclaimed water uses established inthe Spanish legislation.

An Adaptive Field Detection Method For Bridge Scour Monitoring Using Motion-Sensing Radio Transponders (RFIDs), TR-617, 2014

A comprehensive field detection method is proposed that is aimed at developing advanced capability for reliable monitoring, inspection and life estimation of bridge infrastructure. The goal is to utilize Motion-Sensing Radio Transponders (RFIDS) on fully adaptive bridge monitoring to minimize the problems inherent in human inspections of bridges. We developed a novel integrated condition-based maintenance (CBM) framework integrating transformative research in RFID sensors and sensing architecture, for in-situ scour monitoring, state-of-the-art computationally efficient multiscale modeling for scour assessment.

The evolution, maintenance and adaptive function of genetic colour polymorphism in birds.

The hypothesis that ornaments can honestly signal quality only if their expression is condition-dependent has dominated the study of the evolution and function of colour traits. Much less interest has been devoted to the adaptive function of colour traits for which the expression is not, or is to a low extent, sensitive to body condition and the environment in which individuals live. The aim of the present paper is to review the current theoretical and empirical knowledge of the evolution, maintenance and adaptive function of colour plumage traits for which the expression is mainly under genetic control. The finding that in many bird species the inheritance of colour morphs follows the laws of Mendel indicates that genetic colour polymorphism is frequent. Polymorphism may have evolved or be maintained because each colour morph facilitates the exploitation of alternative ecological niches as suggested by the observation that individuals are not randomly distributed among habitats with respect to coloration. Consistent with the hypothesis that different colour morphs are linked to alternative strategies is the finding that in a majority of species polymorphism is associated with reproductive parameters, and behavioural, life-history and physiological traits. Experimental studies showed that such covariations can have a genetic basis. These observations suggest that colour polymorphism has an adaptive function. Aviary and field experiments demonstrated that colour polymorphism is used as a criterion in mate-choice decisions and dominance interactions confirming the claim that conspecifics assess each other's colour morphs. The factors favouring the evolution and maintenance of genetic variation in coloration are reviewed, but empirical data are virtually lacking to assess their importance. Although current theory predicts that only condition-dependent traits can signal quality, the present review shows that genetically inherited morphs can reveal the same qualities. The study of genetic colour polymorphism will provide important and original insights on the adaptive function of conspicuous traits.

Genital Chlamydia trachomatis: understanding the roles of innate and adaptive immunity in vaccine research.

Chlamydia trachomatis is the leading cause of bacterial sexually transmitted disease worldwide, and despite significant advances in chlamydial research, a prophylactic vaccine has yet to be developed. This Gram-negative obligate intracellular bacterium, which often causes asymptomatic infection, may cause pelvic inflammatory disease (PID), ectopic pregnancies, scarring of the fallopian tubes, miscarriage, and infertility when left untreated. In the genital tract, Chlamydia trachomatis infects primarily epithelial cells and requires Th1 immunity for optimal clearance. This review first focuses on the immune cells important in a chlamydial infection. Second, we summarize the research and challenges associated with developing a chlamydial vaccine that elicits a protective Th1-mediated immune response without inducing adverse immunopathologies.

Activation of the NLRP3 inflammasome in dendritic cells induces IL-1beta-dependent adaptive immunity against tumors.

The therapeutic efficacy of anticancer chemotherapies may depend on dendritic cells (DCs), which present antigens from dying cancer cells to prime tumor-specific interferon-gamma (IFN-gamma)-producing T lymphocytes. Here we show that dying tumor cells release ATP, which then acts on P2X(7) purinergic receptors from DCs and triggers the NOD-like receptor family, pyrin domain containing-3 protein (NLRP3)-dependent caspase-1 activation complex ('inflammasome'), allowing for the secretion of interleukin-1beta (IL-1beta). The priming of IFN-gamma-producing CD8+ T cells by dying tumor cells fails in the absence of a functional IL-1 receptor 1 and in Nlpr3-deficient (Nlrp3(-/-)) or caspase-1-deficient (Casp-1(-/-)) mice unless exogenous IL-1beta is provided. Accordingly, anticancer chemotherapy turned out to be inefficient against tumors established in purinergic receptor P2rx7(-/-) or Nlrp3(-/-) or Casp1(-/-) hosts. Anthracycline-treated individuals with breast cancer carrying a loss-of-function allele of P2RX7 developed metastatic disease more rapidly than individuals bearing the normal allele. These results indicate that the NLRP3 inflammasome links the innate and adaptive immune responses against dying tumor cells.

THE USEFUL SIDE OF AMBIVALENCE: Ambivalent attitudes can be adaptive and socially valued

En s'inspirant de la littérature récente qui a dépeint l'ambivalence comme étant adaptative et en lien avec des comportements stratégiques, cette thèse examine le versant utile des attitudes ambivalentes. Elle met tout d'abord en évidence que son expression peut-être sciemment contrôlée et mise en avant pour des raisons d'auto-présentation. De plus, elle démontre que les individus peuvent présenter une attitude ambivalente afin de gagner l'approbation sociale sur un objet d'attitude controversé alors que l'inverse a été observé sur des objets consensuels (Première ligne de recherche). Cette thèse a également révélé que l'expression d'attitudes ambivalentes pouvait amener à être valorisé socialement. En effet, contrairement à des attitudes plus tranchées (pro-normatives ou contre-normatives), les attitudes ambivalentes ont été évaluées de façon plus importante sur la dimension de l'utilité sociale (une dimension qui indique la compétence d'autrui ou encore la propension à évoluer dans la hiérarchie sociale). La valorisation de l'ambivalence n'est apparue que sur la dimension de l'utilité sociale et non sur la dimension de la désirabilité sociale (une dimension qui indique la sympathie d'autrui ainsi que la propension à être apprécié socialement). De plus, ce résultat a été observé sur des thèmes controversés et non sur des thèmes consensuels (Seconde ligne de recherche). Dans l'ensemble cette thèse soutient une approche de l'ambivalence comme donnant lieu à des bénéfices. Elle peut également ouvrir la voie à l'étude de l'ambivalence en lien avec la pensée critique. - Drawing on the recent literature that portrayed ambivalence as being adaptive and linked with strategic behaviors, this thesis examines the useful side of ambivalent attitudes. It first revealed that the expression of ambivalent attitudes could be controlled and purposely displayed for self-presentational concerns. Furthermore, it demonstrated that people could put ambivalence forward to gain social approval when expressing it on controversial social issues, whereas the opposite was true on consensual social issues (First line of research). The thesis also revealed that the expression of ambivalent attitudes could lead to be socially valued. Indeed, contrary to clear-cut attitudes (either pro-normative or counter-normative attitudes), ambivalent attitudes have been evaluated the highest on the social utility dimension (a dimension indicating people's competence as well as the extent to which they are likely to climb in social hierarchy). The valorization of ambivalent attitudes only appeared on social utility and not on social desirability (a dimension indicating people's niceness as well as the extent to which they are likely to be socially appreciated). This effect was true on controversial social issues but not on consensual ones (Second line of research). Overall, this thesis provides support for an approach that conceives attitudinal ambivalence as leading to benefits. It also may open avenues for the study of ambivalence in relation with critical thinking.

Cardiac raptor deletion impairs adaptive hypertrophy, alters metabolic gene expression and causes heart failure in mice

Background: Mammalian target of rapamycin (mTOR), a central regulator of cell growth, is found in two structurally and functionally distinct multiprotein complexes called mTOR complex (mTORC)1 and mTORC2. The specific roles of each of these branches of mTOR signaling have not been dissected in the adult heart. In the present study, we aimed to bring new insights into the function of cardiac mTORC1-mediated signaling in physiological as well as pathological situations.Methods: We generated mice homozygous for loxP-flanked raptor and positive for the tamoxifen-inducible Cre recombinase (MerCreMer) under control of the α- myosin heavy chain promoter. The raptor gene encodes an essential component of mTORC1. Gene ablation was induced at the age of 10-12 weeks, and two weeks later the raptor cardiac-knockout (raptor-cKO) mice started voluntary cagewheel exercise or were subjected to transverse aortic constriction (TAC) to induce pressure overload.Results: In sedentary raptor-cKO mice, ejection fractions gradually decreased, resulting in significantly reduced values at 38 days (P < 0.001). Raptor-cKO mice started to die during the fifth week after the last tamoxifen injection. At that time, the mortality rate was 36% in sedentary (n = 11) and 64% in exercising (n = 14) mice. TAC-induced pressure overload resulted in severe cardiac dysfunction already at earlier timepoints. Thus, at 7-9 days after surgery, ejection fraction and fractional shortening values were 22.3% vs 43.5% and 10.2% vs 21.5% in raptor-cKO vs wild-type mice, respectively. This was accompanied by significant reductions of ventricular wall and septal thickness as well as an increase in left ventricular internal diameter. Moreover, ventricular weight to tibial length ratios were increased in wild-type, but not in the raptor-cKO TAC mice. Together, this shows that raptor-cKO mice rapidly developed dilated cardiomyopathy without going through a phase of adaptive hypertrophy. Expression of ANP and β-MHC was induced in all raptor-cKO mice irrespective of the cardiac load conditions. Consistent with reduced mTORC1 activity, phosphorylation of ribosomal S6 kinase and 4E-BP1 was blunted, indicating reduced protein synthesis. Moreover, expression of multiple genes involved in the regulation of energy metabolism was altered, and followed by a shift from fatty acid to glucose oxidation.Conclusion: Our study suggests that mTORC1 coordinates protein and energy metabolic pathways in the heart. Moreover, we demonstrate that raptor is essential for the cardiac adaptation to increased workload and importantly, also for normal physiological cardiac function.

Viticulture under climate change : understanding vulnerability and adaptive capacity of wineries and growers. A case study in El Penedès region, Catalonia

Climate change may pose challenges and opportunities to viticulture, and much research has focused in studying the likely impacts on grapes and wine production in different regions worldwide. This study assesses the vulnerability and adaptive capacity of the viticulture sector under changing climate conditions, based on a case study in El Penedès region, Catalonia. Farm assets, livelihood strategies, farmer-market interactions and climate changes perceptions are analysed through semi-structured interviews with different types of wineries and growers. Both types of actors are equally exposed to biophysical stressors but unevenly affected by socioeconomic changes. While wineries are vulnerable because of the current economic crisis and the lack of diversification of their work, which may affect their income or production, growers are mainly affected by the low prices of their products and the lack of fix contracts. These socioeconomic stressors strongly condition their capacity to adapt to climate change, meaning that growers prioritize their immediate income problems, rather than future socioeconomic or climate threats. Therefore, growers undertake reactive adaptation to climate changing conditions, mainly based on ancient knowledge, whilst wineries combine both reactive and anticipatory adaptation practices. These circumstances should be addressed in order to allow better anticipatory adaptation to be implemented, thus avoiding future climate threats.

The underestimation of compliance to direct help requests explained by adaptive sampling

Helping behavior is any intentional behavior that benefits another living being or group (Hogg & Vaughan, 2010). People tend to underestimate the probability that others will comply with their direct requests for help (Flynn & Lake, 2008). This implies that when they need help, they will assess the probability of getting it (De Paulo, 1982, cited in Flynn & Lake, 2008) and then they will tend to estimate one that is actually lower than the real chance, so they may not even consider worth asking for it. Existing explanations for this phenomenon attribute it to a mistaken cost computation by the help seeker, who will emphasize the instrumental cost of “saying yes”, ignoring that the potential helper also needs to take into account the social cost of saying “no”. And the truth is that, especially in face-to-face interactions, the discomfort caused by refusing to help can be very high. In short, help seekers tend to fail to realize that it might be more costly to refuse to comply with a help request rather than accepting. A similar effect has been observed when estimating trustworthiness of people. Fetchenhauer and Dunning (2010) showed that people also tend to underestimate it. This bias is reduced when, instead of asymmetric feedback (getting feedback only when deciding to trust the other person), symmetric feedback (always given) was provided. This cause could as well be applicable to help seeking as people only receive feedback when they actually make their request but not otherwise. Fazio, Shook, and Eiser (2004) studied something that could be reinforcing these outcomes: Learning asymmetries. By means of a computer game called BeanFest, they showed that people learn better about negatively valenced objects (beans in this case) than about positively valenced ones. This learning asymmetry esteemed from “information gain being contingent on approach behavior” (p. 293), which could be identified with what Fetchenhauer and Dunning mention as ‘asymmetric feedback’, and hence also with help requests. Fazio et al. also found a generalization asymmetry in favor of negative attitudes versus positive ones. They attributed it to a negativity bias that “weights resemblance to a known negative more heavily than resemblance to a positive” (p. 300). Applied to help seeking scenarios, this would mean that when facing an unknown situation, people would tend to generalize and infer that is more likely that they get a negative rather than a positive outcome from it, so, along with what it was said before, people will be more inclined to think that they will get a “no” when requesting help. Denrell and Le Mens (2011) present a different perspective when trying to explain judgment biases in general. They deviate from the classical inappropriate information processing (depicted among other by Fiske & Taylor, 2007, and Tversky & Kahneman, 1974) and explain this in terms of ‘adaptive sampling’. Adaptive sampling is a sampling mechanism in which the selection of sample items is conditioned by the values of the variable of interest previously observed (Thompson, 2011). Sampling adaptively allows individuals to safeguard themselves from experiences they went through once and turned out to lay negative outcomes. However, it also prevents them from giving a second chance to those experiences to get an updated outcome that could maybe turn into a positive one, a more positive one, or just one that regresses to the mean, whatever direction that implies. That, as Denrell and Le Mens (2011) explained, makes sense: If you go to a restaurant, and you did not like the food, you do not choose that restaurant again. This is what we think could be happening when asking for help: When we get a “no”, we stop asking. And here, we want to provide a complementary explanation for the underestimation of the probability that others comply with our direct help requests based on adaptive sampling. First, we will develop and explain a model that represents the theory. Later on, we will test it empirically by means of experiments, and will elaborate on the analysis of its results.