MtbHLH1, a bHLH transcription factor involved in Medicago truncatula nodule vascular patterning and nodule to plant metabolic exchanges

This study aimed at defining the role of a basic helix–loop–helix (bHLH) transcription factor gene from Medicago truncatula, MtbHLH1, whose expression is upregulated during the development of root nodules produced upon infection by rhizobia bacteria.We used MtbHLH1 promoter::GUS fusions and quantitative reverse-transcription polymerase chain reaction analyses to finely characterize the MtbHLH1 expression pattern. We altered MtbHLH1 function by expressing a dominantly repressed construct (CRES-T approach) and looked for possible MtbHLH1 target genes by transcriptomics.We found that MtbHLH1 is expressed in nodule primordia cells derived from pericycle divisions, in nodule vascular bundles (VBs) and in uninfected cells of the nitrogen (N) fixation zone. MtbHLH1 is also expressed in root tips, lateral root primordia cells and root VBs, and induced upon auxin treatment. Altering MtbHLH1 function led to an unusual phenotype, with a modified patterning of nodule VB development and a reduced growth of aerial parts of the plant, even though the nodules were able to fix atmospheric N. Several putative MtbHLH1 regulated genes were identified, including an asparagine synthase and a LOB (lateral organ boundary) transcription factor.Our results suggest that the MtbHLH1 gene is involved in the control of nodule vasculature patterning and nutrient exchanges between nodules and roots

A phylogenetically conserved group of nuclear factor-Y transcription factors interact to control nodulation in legumes

The endosymbiotic association between legumes and soil bacteria called rhizobia leads to the formation of a new root-derived organ called the nodule in which differentiated bacteria convert atmospheric nitrogen into a form that can be assimilated by the host plant. Successful root infection by rhizobia and nodule organogenesis require the activation of symbiotic genes that are controlled by a set of transcription factors (TFs). We recently identified Medicago truncatula nuclear factor-YA1 (MtNF-YA1) and MtNF-YA2 as two M. truncatula TFs playing a central role during key steps of the Sinorhizobium meliloti-M. truncatula symbiotic interaction. NF-YA TFs interact with NF-YB and NF-YC subunits to regulate target genes containing the CCAAT box consensus sequence. In this study, using a yeast two-hybrid screen approach, we identified the NF-YB and NF-YC subunits able to interact with MtNF-YA1 and MtNF-YA2. In yeast (Saccharomyces cerevisiae) and in planta, we further demonstrated by both coimmunoprecipitation and bimolecular fluorescence complementation that these NF-YA, -B, and -C subunits interact and form a stable NF-Y heterotrimeric complex. Reverse genetic and chromatin immunoprecipitation-PCR approaches revealed the importance of these newly identified NF-YB and NF-YC subunits for rhizobial symbiosis and binding to the promoter of MtERN1 (for Ethylene Responsive factor required for Nodulation), a direct target gene of MtNF-YA1 and MtNF-YA2. Finally, we verified that a similar trimer is formed in planta by the common bean (Phaseolus vulgaris) NF-Y subunits, revealing the existence of evolutionary conserved NF-Y protein complexes to control nodulation in leguminous plants. This sheds light on the process whereby an ancient heterotrimeric TF mainly controlling cell division in animals has acquired specialized functions in plants.Instituto de Biotecnologia y Biologia Molecula

A phylogenetically conserved group of nuclear factor-Y transcription factors interact to control nodulation in legumes

The endosymbiotic association between legumes and soil bacteria called rhizobia leads to the formation of a new root-derived organ called the nodule in which differentiated bacteria convert atmospheric nitrogen into a form that can be assimilated by the host plant. Successful root infection by rhizobia and nodule organogenesis require the activation of symbiotic genes that are controlled by a set of transcription factors (TFs). We recently identified Medicago truncatula nuclear factor-YA1 (MtNF-YA1) and MtNF-YA2 as two M. truncatula TFs playing a central role during key steps of the Sinorhizobium meliloti-M. truncatula symbiotic interaction. NF-YA TFs interact with NF-YB and NF-YC subunits to regulate target genes containing the CCAAT box consensus sequence. In this study, using a yeast two-hybrid screen approach, we identified the NF-YB and NF-YC subunits able to interact with MtNF-YA1 and MtNF-YA2. In yeast (Saccharomyces cerevisiae) and in planta, we further demonstrated by both coimmunoprecipitation and bimolecular fluorescence complementation that these NF-YA, -B, and -C subunits interact and form a stable NF-Y heterotrimeric complex. Reverse genetic and chromatin immunoprecipitation-PCR approaches revealed the importance of these newly identified NF-YB and NF-YC subunits for rhizobial symbiosis and binding to the promoter of MtERN1 (for Ethylene Responsive factor required for Nodulation), a direct target gene of MtNF-YA1 and MtNF-YA2. Finally, we verified that a similar trimer is formed in planta by the common bean (Phaseolus vulgaris) NF-Y subunits, revealing the existence of evolutionary conserved NF-Y protein complexes to control nodulation in leguminous plants. This sheds light on the process whereby an ancient heterotrimeric TF mainly controlling cell division in animals has acquired specialized functions in plants.Instituto de Biotecnologia y Biologia Molecula

Contribution de la sociocratie à la gestion de projets collaboratifs ? Retours d’expériences du secteur social, de la formation et de la recherche

National audienc

Effects of Anticholinergic Burden on Verbal Memory Performance in First-Episode Psychosis.

OBJECTIVES: Antipsychotics are widely used to treat first-episode psychosis but may have an anticholinergic burden, that is, a cumulative effect of medications that block the cholinergic system. Studies suggest that a high anticholinergic burden negatively affects memory in psychosis, where cognitive deficits, particularly those in verbal memory, are a core feature of the disease. The present study sought to replicate this in a large cohort of well-characterized first-episode psychosis patients. We expected that patients in the highest anticholinergic burden group would exhibit the poorest verbal memory compared to those with low anticholinergic burden and healthy controls at baseline (3 months following admission). We further hypothesized that over time, at month 12, patients verbal memory performance would improve but would remain inferior to controls. METHODS: Patients (n  =  311; low anticholinergic burden [n  =  241] and high anticholinergic burden [n  =  70], defined by a Drug Burden Index cut-off of 1) and healthy controls (n  =  128) completed a clinical and neurocognitive battery including parts of the Wechsler Memory Scale at months 3 and 12. RESULTS: Cross-sectionally, using an analysis of variance, patients in the highest anticholinergic burden group had the poorest performance in verbal memory when compared to the other groups at month 3, F(2,430)  =  52.33, P < 0.001. Longitudinally, using a Generalized Estimating Equation model, the verbal memory performance of all groups improved over time. However, patients performance overall remained poorer than the controls. CONCLUSION: These findings highlight the importance of considering the anticholinergic burden when prescribing medications in the early stages of the disease

Effects of Anticholinergic Burden on Verbal Memory Performance in First-Episode Psychosis

Antipsychotics are widely used to treat first-episode psychosis but may have an anticholinergic burden, i.e., a cumulative effect of medications that block the cholinergic system. Studies suggest that a high anticholinergic burden negatively affects memory in psychosis, where cognitive deficits, particularly those in verbal memory, are a core feature of the disease. The present study sought to replicate this in a large cohort of well-characterized first-episode psychosis patients. We expected that patients in the highest anticholinergic burden group would exhibit the poorest verbal memory compared to those with low anticholinergic burden and to healthy controls at baseline (3 months following admission). We further hypothesized that over time, at month 12, patients' verbal memory performance would improve but would remain inferior to controls. Patients (n=311; low anticholinergic burden [n=241] and high anticholinergic burden [n=70], defined by a Drug Burden Index cut-off of 1) and controls (n=128) completed a clinical and neurocognitive battery including parts of the Wechsler Memory Scale at month 3 and 12. Cross-sectionally, using an ANOVA, patients in the highest anticholinergic burden group had the poorest performance in verbal memory when compared to the other groups at month 3 (F(2,430)=52.33, P<0.001). Longitudinally, using a Generalized Estimating Equation model, the verbal memory performance of all groups improved over time. However, patients' performance overall remained poorer than the controls. These findings highlight the importance of considering the anticholinergic burden when prescribing medications in the early stages of the disease

Can routinely collected national data on childhood morbidity and mortality from diarrhea be used to monitor health impact of rotavirus vaccination in Africa? Examination of pre-vaccine baseline data from Rwanda.

BACKGROUND: As rotavirus vaccine is introduced into routine childhood immunization programs in Africa, understanding its impact on diarrheal disease burden is important. The objective of this analysis was to determine whether routinely collected health information on national diarrhea hospitalizations, in-hospital deaths and outpatient visits would be useful to monitor rotavirus vaccine impact. METHODS: We analyzed data for all-cause, nonbloody diarrheal disease among children <5 years of age from the routine health management information system (HMIS) in Rwanda from January 2008 through December 2011. We described trends in absolute numbers of inpatient admissions, in-hospital deaths and outpatient visits by year, age and setting. RESULTS: All-cause, nonbloody diarrheal hospitalizations and outpatient visits among children <5 years of age in Rwanda from 2008 to 2011 peaked during the June to August dry season, coinciding with the rotavirus season. The bulk of the diarrheal disease burden occurred in children <1 year of age. Health centers provided many care to children with diarrhea including 60-72% of hospitalizations and 97-99% of outpatient visits. Many in-hospital diarrheal deaths (84%) occurred in district hospitals. DISCUSSION: Given the stable and consistent trends and the prominent seasonality consistent with that of rotavirus, HMIS data should provide a useful baseline to monitor rotavirus vaccine impact on the overall diarrheal disease burden in Rwanda. Active, sentinel surveillance for rotavirus diarrhea will help interpret changes in diarrheal disease trends following vaccine introduction. Other countries planning rotavirus vaccine introduction should explore the availability and quality of their HMIS data. © 2013 Lippincott Williams and Wilkins.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Can routinely collected national data on childhood morbidity and mortality from diarrhea be used to monitor health impact of rotavirus vaccination in Africa? Examination of pre-vaccine baseline data from Rwanda.

info:eu-repo/semantics/publishe

Two CCAAT box-binding transcription factors redundantly regulate early steps of the legume-rhizobia endosymbiosis

International audienceDuring endosymbiotic interactions between legume plants and nitrogen-fixing rhizobia, successful root infection by bacteria and nodule organogenesis requires the perception and transduction of bacterial lipo-chitooligosaccharidic signal called Nod factor (NF). NF perception in legume roots leads to the activation of an early signaling pathway and of a set of symbiotic genes which is controlled by specific early transcription factors (TFs) including CYCLOPS/IPD3, NSP1, NSP2, ERN1 and NIN. In this study, we bring convincing evidence that the Medicago truncatula CCAAT-box-binding NF-YA1 TF, previously associated with later stages of rhizobial infection and nodule meristem formation is, together with its closest homolog NF-YA2, also an essential positive regulator of the NF-signaling pathway. Here we show that NF-YA1 and NF-YA2 are both expressed in epidermal cells responding to NFs and their knock-down by reverse genetic approaches severely affects the NF-induced expression of symbiotic genes and rhizobial infection. Further over-expression, transactivation and ChIP-PCR approaches indicate that NF-YA1 and NF-YA2 function, at least in part, via the direct activation of ERN1. We thus propose a model in which NF-YA1 and NF-YA2 appear as early symbiotic regulators acting downstream of DMI3 and NIN and possibly within the same regulatory complexes as NSP1/2 to directly activate the expression of ERN1