EXO modifies sucrose and trehalose responses and connects the extracellular carbon status to growth

Plants have the capacity to adapt growth to changing environmental conditions. This implies the modulation of metabolism according to the availability of carbon (C). Particular interest in the response to the C availability is based on the increasing atmospheric levels of CO2. Several regulatory pathways that link the C status to growth have emerged. The extracellular EXO protein is essential for cell expansion and promotes shoot and root growth. Homologous proteins were identified in evolutionarily distant green plants. We show here that the EXO protein connects growth with C responses. The exo mutant displayed altered responses to exogenous sucrose supplemented to the growth medium. Impaired growth of the mutant in synthetic medium was associated with the accumulation of starch and anthocyanins, altered expression of sugar-responsive genes, and increased abscisic acid levels. Thus, EXO modulates several responses related to the C availability. Growth retardation on medium supplemented with 2-deoxy-glucose, mannose, and palatinose was similar to the wild type. Trehalose feeding stimulated root growth and shoot biomass production of exo plants whereas it inhibited growth of the wild type. The phenotypic features of the exo mutant suggest that apoplastic processes coordinate growth and C responses

Evaluating the effect of operating variables on energy consumption in stirred mills Mussa Lisso.

Includes abstract.Includes bibliographical references.High grade ores have largely been depleted and those currently being treated are low grade, complex and sometimes finely disseminated, requiring fine grinding to liberate valuable minerals. For fine grinding applications, conventional tumbling mills are energy intensive. More energy efficient technologies such as stirred mills have been developed and widely used for fine and ultra-fine grinding. In this study, the effects of residence time, solids concentration, impeller speed, impeller type, media size and media density on energy consumption in a batch vertical stirred mill were investigated. The effect of energy on mill performance was assessed using the perfect mixing mill model. In addition, the effect of media stress intensity on grind and energy efficiency at constant residence time was also investigated. It was found that irrespective of the method of altering the energy input, the fineness of grind improved with increase in the specific energy input. This suggests that energy is the key driver for size reduction. The perfect mixing model can be used to assess mill performance and the breakage rates generally increased with increase in the specific energy input, impeller speed and solids concentration. The media stress intensity approach is useful in assessing mill performance in stirred mills at constant residence time. The fineness of grind improved when the media stress intensity was varied from 4.41×10-3 to 27.41×10-3Nm. In addition, the specific energy required to produce material below 25μm and 38μm decreased with an increase in the media stress intensity. When slurry density effects were considered, an optimum stress intensity was observed with respect to specific energy required to produce material below 25μm and 38μm. It was recommended that additional test work be carried out to investigate the effect of media size in the range -6.7mm + 2mm on energy efficiency. It was also recommended that tests be carried out at impeller speed between 600rpm and 1500rpm to assess how mill performance increases even at relatively high impeller speeds. In addition, a model predicting the specific energy using the impeller speed and solids concentration can also be developed

NFX1-LIKE2 (NFXL2) Suppresses Abscisic Acid Accumulation and Stomatal Closure in Arabidopsis thaliana

The NFX1-LIKE1 (NFXL1) and NFXL2 genes were identified as regulators of salt stress responses. The NFXL1 protein is a nuclear factor that positively affects adaptation to salt stress. The nfxl1-1 loss-of-function mutant displayed reduced survival rates under salt and high light stress. In contrast, the nfxl2-1 mutant, defective in the NFXL2 gene, and NFXL2-antisense plants exhibited enhanced survival under these conditions. We show here that the loss of NFXL2 function results in abscisic acid (ABA) overaccumulation, reduced stomatal conductance, and enhanced survival under drought stress. The nfxl2-1 mutant displayed reduced stomatal aperture under all conditions tested. Fusicoccin treatment, exposition to increasing light intensities, and supply of decreasing CO2 concentrations demonstrated full opening capacity of nfxl2-1 stomata. Reduced stomatal opening presumably is a consequence of elevated ABA levels. Furthermore, seedling growth, root growth, and stomatal closure were hypersensitive to exogenous ABA. The enhanced ABA responses may contribute to the improved drought stress resistance of the mutant. Three NFXL2 splice variants were cloned and named NFXL2-78, NFXL2-97, and NFXL2-100 according to the molecular weight of the putative proteins. Translational fusions to the green fluorescent protein suggest nuclear localisation of the NFXL2 proteins. Stable expression of the NFXL2-78 splice variant in nfxl2-1 plants largely complemented the mutant phenotype. Our data show that NFXL2 controls ABA levels and suppresses ABA responses. NFXL2 may prevent unnecessary and costly stress adaptation under favourable conditions

The extracellular EXO protein mediates cell expansion in Arabidopsis leaves

<p>Abstract</p> <p>Background</p> <p>The <it>EXO </it>(<it>EXORDIUM</it>) gene was identified as a potential mediator of brassinosteroid (BR)-promoted growth. It is part of a gene family with eight members in Arabidopsis. <it>EXO </it>gene expression is under control of BR, and <it>EXO </it>overexpression promotes shoot and root growth. In this study, the consequences of loss of <it>EXO </it>function are described.</p> <p>Results</p> <p>The <it>exo </it>loss of function mutant showed diminished leaf and root growth and reduced biomass production. Light and scanning electron microscopy analyses revealed that impaired leaf growth is due to reduced cell expansion. Epidermis, palisade, and spongy parenchyma cells were smaller in comparison to the wild-type. The <it>exo </it>mutant showed reduced brassinolide-induced cotyledon and hypocotyl growth. In contrast, <it>exo </it>roots were significantly more sensitive to the inhibitory effect of synthetic brassinolide. Apart from reduced growth, <it>exo </it>did not show severe morphological abnormalities. Gene expression analyses of leaf material identified genes that showed robust EXO-dependent expression. Growth-related genes such as <it>WAK1</it>, <it>EXP5</it>, and <it>KCS1</it>, and genes involved in primary and secondary metabolism showed weaker expression in <it>exo </it>than in wild-type plants. However, the vast majority of BR-regulated genes were normally expressed in <it>exo</it>. HA- and GFP-tagged EXO proteins were targeted to the apoplast.</p> <p>Conclusion</p> <p>The <it>EXO </it>gene is essential for cell expansion in leaves. Gene expression patterns and growth assays suggest that EXO mediates BR-induced leaf growth. However, EXO does not control BR-levels or BR-sensitivity in the shoot. EXO presumably is involved in a signalling process which coordinates BR-responses with environmental or developmental signals. The hypersensitivity of <it>exo </it>roots to BR suggests that EXO plays a diverse role in the control of BR responses in the root.</p

The extracellular EXO protein mediates cell expansion in Arabidopsis leaves

<p>Abstract</p> <p>Background</p> <p>The <it>EXO </it>(<it>EXORDIUM</it>) gene was identified as a potential mediator of brassinosteroid (BR)-promoted growth. It is part of a gene family with eight members in Arabidopsis. <it>EXO </it>gene expression is under control of BR, and <it>EXO </it>overexpression promotes shoot and root growth. In this study, the consequences of loss of <it>EXO </it>function are described.</p> <p>Results</p> <p>The <it>exo </it>loss of function mutant showed diminished leaf and root growth and reduced biomass production. Light and scanning electron microscopy analyses revealed that impaired leaf growth is due to reduced cell expansion. Epidermis, palisade, and spongy parenchyma cells were smaller in comparison to the wild-type. The <it>exo </it>mutant showed reduced brassinolide-induced cotyledon and hypocotyl growth. In contrast, <it>exo </it>roots were significantly more sensitive to the inhibitory effect of synthetic brassinolide. Apart from reduced growth, <it>exo </it>did not show severe morphological abnormalities. Gene expression analyses of leaf material identified genes that showed robust EXO-dependent expression. Growth-related genes such as <it>WAK1</it>, <it>EXP5</it>, and <it>KCS1</it>, and genes involved in primary and secondary metabolism showed weaker expression in <it>exo </it>than in wild-type plants. However, the vast majority of BR-regulated genes were normally expressed in <it>exo</it>. HA- and GFP-tagged EXO proteins were targeted to the apoplast.</p> <p>Conclusion</p> <p>The <it>EXO </it>gene is essential for cell expansion in leaves. Gene expression patterns and growth assays suggest that EXO mediates BR-induced leaf growth. However, EXO does not control BR-levels or BR-sensitivity in the shoot. EXO presumably is involved in a signalling process which coordinates BR-responses with environmental or developmental signals. The hypersensitivity of <it>exo </it>roots to BR suggests that EXO plays a diverse role in the control of BR responses in the root.</p

L’approche théorique des communs : une nouvelle grille d’analyse des interventions collectives environnementales visant la protection des lacs habités dans la région des Laurentides

Plus de trente ans après l’adoption de la Politique de protection des rives, du littoral et des plaines inondables (abrogée par le Régime transitoire le 1er mars 2022), les impacts de l’occupation humaine sur les rives et le littoral demeurent un enjeu d’actualité. Même si la littérature québécoise souligne les limites inhérentes aux interventions municipales et l’opinion des experts en sciences naturelles, en droit ou en planification du territoire, le point de vue des résidents riverains est peu documenté. Dans ce mémoire, nous voulons explorer ce sujet à travers le cadre théorique des communs. Le mémoire vise à approfondir nos connaissances du point de vue des riverains et des autres intervenants qui participent aux interventions collectives environnementales visant à protéger les lacs habités de la région administrative des Laurentides. Nous tenterons donc de répondre à la question : comment repenser la protection des rives et du littoral des lacs habités en milieu de villégiature? Les résultats des entretiens semi-dirigés permettent d’expliquer 3 types de solutions : 1) que l’intervention collective environnementale constitue une piste de solution crédible en matière de protection des rives et du littoral; 2) que les impacts de l’occupation humaine sur les rives et le littoral des lacs habités en milieu de villégiature peuvent être pensés comme un problème de ressources collectives; 3) que les initiatives citoyennes et associatives ne se traduisent pas nécessairement par l’émergence de communs. Notre réflexion prospective permet de dire que les municipalités locales et les associations de lacs sont complémentaires à plus d’un titre et constituent un partenariat « public-commun ». Ces deux organisations sont de nature à accroître le nombre et l’étendue des interventions collectives visant directement ou indirectement la protection des rives et du littoral des lacs habités en milieu de villégiature.More than thirty years after the adoption of the Protection Policy for Lakeshores, Riverbanks, Littoral Zones and Floodplains Environmental Quality Act (repealed by the transitional regime on March 1, 2022), the impacts of human occupation on lakeshores and littoral zones remain a topical issue. Even if the Quebec literature emphasizes the inherent limits of municipal interventions and the opinion of experts in the natural sciences, law or urban planning, the point of view of the shoreline residents is poorly documented. In this thesis, we explore this topic through the theoretical framework of the commons. The thesis aims to deepen our knowledge from the point of view of shoreline residents and other stakeholders who participate in collective environmental interventions aimed at protecting the inhabited lakes of the administrative region of the Laurentians. We will therefore try to answer the question: how to rethink the protection of the lakeshores and littoral zones of inhabited lakes in resort areas? The results of the semi-directed interviews make it possible to explain 3 types of solutions: 1) that collective environmental intervention constitutes a credible solution for the protection of lakeshores and littoral zones; 2) that the impacts of human occupation on the lakeshores and littoral zones of inhabited lakes in resort areas can be thought of as a problem of collective resources; 3) that citizen and associative initiatives do not necessarily result in the emergence of commons. Our forward thinking allows us to say that local municipalities and lake associations are complementary in more ways than one and constitute a “public-common” partnership. These two organizations are likely to increase the number and extent of collective interventions aimed directly or indirectly at protecting the lakeshores and littoral zones of inhabited lakes in resort areas

Identification of brassinosteroid-related genes by means of transcript co-response analyses

The comprehensive systems-biology database (CSB.DB) was used to reveal brassinosteroid (BR)-related genes from expression profiles based on co-response analyses. Genes exhibiting simultaneous changes in transcript levels are candidates of common transcriptional regulation. Combining numerous different experiments in data matrices allows ruling out outliers and conditional changes of transcript levels. CSB.DB was queried for transcriptional co-responses with the BR-signalling components BRI1 and BAK1: 301 out of 9694 genes represented in the nasc0271 database showed co-responses with both genes. As expected, these genes comprised pathway-involved genes (e.g. 72 BR-induced genes), because the BRI1 and BAK1 proteins are required for BR-responses. But transcript co-response takes the analysis a step further compared with direct approaches because BR-related non BR-responsive genes were identified. Insights into networks and the functional context of genes are provided, because factors determining expression patterns are reflected in correlations. Our findings demonstrate that transcript co-response analysis presents a valuable resource to uncover common regulatory patterns of genes. Different data matrices in CSB.DB allow examination of specific biological questions. All matrices are publicly available through CSB.DB. This work presents one possible roadmap to use the CSB.DB resources

SVD-based Anatomy of Gene Expressions for Correlation Analysis in Arabidopsis thaliana

Gene co-expression analysis has been widely used in recent years for predicting unknown gene function and its regulatory mechanisms. The predictive accuracy depends on the quality and the diversity of data set used. In this report, we applied singular value decomposition (SVD) to array experiments in public databases to find that co-expression linkage could be estimated by a much smaller number of array data. Correlations of co-expressed gene were assessed using two regulatory mechanisms (feedback loop of the fundamental circadian clock and a global transcription factor Myb28), as well as metabolic pathways in the AraCyc database. Our conclusion is that a smaller number of informative arrays across tissues can suffice to reproduce comparable results with a state-of-the-art co-expression software tool. In our SVD analysis on Arabidopsis data set, array experiments that contributed most as the principal components included stamen development, germinating seed and stress responses on leaf

Effects of Alpha-Lipoic Acid and Myoinositol Supplementation on the Oocyte Enviroment of Obese Infertile Women

INTRODUCTION Obesity is characterized by increased inflammation and oxidative stress, resulting in adverse effects on women reproductive potential. Antioxidant supplementation may exert a positive effect on the obese ovarian environment. Indeed, we preliminarily observed a reduction of mitochondrial (mt) DNA content, a marker of oxidative stress, in granulosa cells of obese infertile women supplemented with Sinopol\uae (Laborest SpA), composed by alpha-lipoic acid (ALA) 800 mg, myoinositol (MYO) 2 g, folic acid (FA) 400 ug. This suggested a potential role of Sinopol\uae in reducing oxidative stress in the obese ovarian environment. Here we analyzed Total Antioxidant Capacity (TAC) in follicular fluid and mtDNA levels in granulosa cells, in a larger population of infertile women undergoing in vitro fertilization (IVF). METHODS 19 normal weight (NW) and 24 obese (OB) infertile women were enrolled in our IVF center. Infertility was investigated and a non-ovarian diagnosis was made. Patients did not present any additional pathology. All women were provided with FA and among them 15 OB (OB-SIN) were also supplemented with ALA and MYO, for 2 months before ovarian stimulation. Follicular fluid (FF) and granulosa cells (GC) were collected after oocyte retrieval. TAC was measured in FF by enzymatic assay, mtDNA levels evaluated in GC by Real-time PCR. Results were compared by ANOVA and correlations assessed by Pearson\u2019s correlation (SPSS; IBM). RESULTS OB groups had similar BMI (OB patients supplemented with only folic acid (OB-F): 30.2 \ub1 0.7; OB-SIN: 32.7 \ub1 1.1 kg/m2). Women age was similar in all groups (NW: 36.7 \ub1 0.6; OB-F: 37.6 \ub1 1.7; OB-SIN: 35.9 \ub1 1.1 years). Among OB women, antioxidant capacity was significantly higher in OB-SIN than in OB-F. mtDNA levels showed an opposite trend, being decreased in OB-SIN and increased in OB-F compared to NW, though not reaching statistical significance. mtDNA levels were significantly and inversely correlated with the number of total oocytes and metaphase II (mature) oocytes. Pregnancy rate was similar in NW (36.8%) and OB-SIN (33.3%) women, while it was lower in OB-F patients (11.1%). CONCLUSION We analyzed molecular markers in granulosa cells and follicular fluid as indicators of oocytes oxidative state. Our results suggest that supplementation with a compound of ALA -a natural antioxidant, cofactor in the mt respiratory chain- and MYO -an insulin-sensitizer- might increase antioxidant defenses and reduce oxidative stress in the obese ovarian environment, possibly contributing at restoring physiological conditions. This might improve IVF pregnancy rates in obese infertile women. Further studies are needed to clarify the synergic action of ALA, MYO and FA on the oocyte oxidative environment. Supported by Laborest Sp

Rank of Correlation Coefficient as a Comparable Measure for Biological Significance of Gene Coexpression

Information regarding gene coexpression is useful to predict gene function. Several databases have been constructed for gene coexpression in model organisms based on a large amount of publicly available gene expression data measured by GeneChip platforms. In these databases, Pearson's correlation coefficients (PCCs) of gene expression patterns are widely used as a measure of gene coexpression. Although the coexpression measure or GeneChip summarization method affects the performance of the gene coexpression database, previous studies for these calculation procedures were tested with only a small number of samples and a particular species. To evaluate the effectiveness of coexpression measures, assessments with large-scale microarray data are required. We first examined characteristics of PCC and found that the optimal PCC threshold to retrieve functionally related genes was affected by the method of gene expression database construction and the target gene function. In addition, we found that this problem could be overcome when we used correlation ranks instead of correlation values. This observation was evaluated by large-scale gene expression data for four species: Arabidopsis, human, mouse and rat