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

Le Forum, Vol. 46 #1 & #2

https://digitalcommons.library.umaine.edu/francoamericain_forum/1110/thumbnail.jp

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

Role of peptide substrate structure in the selective processing of peptide prohormones at basic amino acid pairs by endoproteases

AbstractThree putative processing enzymes, each with defined action in a prohormone system, a ‘pro-ocytocin-neurophysin convertase’ from bovine neurohypophysis secretory granules, a ‘Leu-enkephalin Arg6 generating enzyme’ from human CSF and the endoprotease from the ‘S-28 convertase’ complex of rat brain cortex, were tested for their ability to hydrolyze peptides deriving from pro-ocytocin, pro-enkephalin B and pro-somatostatin, respectively at pairs of basic amino acids. The observations suggest that structural parameters specified by the peptide region around the dibasic moieties govern recognition by the enzyme and define which peptide bond is hydrolyzed

La collection CNRZ : les enjeux, les missions et les perspectives.

International 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