Influence of the soil climate on the evolution of the nitrogenous compounds in the soils of Lorraine and their consequences on the water quality

In order to establish the influence of the soil climate on the transfer mechanisms of the element N, under naturally constituted forms or industrial syntheses, in soil, water, plant systems, we put in place in the fields two procedures. The first concerned the cultivated sites of the four main types of soil found in Lorraine. The annual lixiviation of nitrates beyond the Ap level can be large and go beyond 100kg / ha of N.NO3 -. It varies according to the soils, the year and the season and we observe that the nitrates are mainly lixiviated in autumn. The values obtained in-situ, compared to those of the potential mineralization in controlled conditions, show the importance of the interaction between climactic parameters and biophysical chemical properties of the soils intervening on the mineralization of the endogenous nitrogen stocks thus the risks of lixiviation notably between crops. Then on a light chalk/clay soil, the burying of a carbon substrate (hop) in end of season, allowed a limitation to the annual lixiviation of the nitrates of about 25%. The use of a fertilizer marked under controlled conditions, allowed us to see the formation of different sections of the internal cycle of the nitrogen and the bio availability of this fertilizer for a spring crop while allowing for the risks of enrichment in nitrate ions in the underlying waters. This study allowed us to establish the participation of the fertilizer in the possible risks of a pollution of nitrates to a level of 21%; also to underline the importance of the duration of the microbic biochemical immobilizations of fertilizers given to these four types of soils; finally, we observe a variety of the kinetic of remineralization from the newly-formed different organic azotes.Afin de préciser l'influence du pédoclimat sur les mécanismes de transfert de l'élément azote (sous formes de composés naturels ou de composés issus de synthèses industrielles) dans les systèmes sols, eaux, plantes, nous avons mis en place plusieurs protocoles. Dans le premier les horizons cultivés des quatre principaux types de sols lorrains ont été pris en considération et soumis aux mêmes contraintes climatiques. La lixiviation des nitrates au-delà de l'horizon Ap est importante et peut dépasser annuellement 100 kg/ha de N.NO-3. Elle varie selon les sols, l'année et la saison et nous constatons que les nitrates sont majoritairement lixiviés en automne. Les valeurs obtenues in situ, comparées à celles du potentiel de minéralisation en conditions contrôlées, montrent toute l'importance de l'interaction entre les paramètres climatiques et les propriétés bio-physico-chimiques des sols sur l'expression de la minéralisation des réserves azotées endogènes, donc de leur potentiel de lixiviation. Un second protocole a permis de mettre en évidence une limitation de la lixiviation des nitrates d'environ 25 % suite à l'enfouissement automnal d'un substrat carboné (paille d'orge). L'utilisation d'un engrais marqué, nous a permis d'observer l'évolution des différents compartiments du cycle interne de l'azote et de leur biodisponibilité pour une céréale de printemps tout en prévoyant les risques d'enrichissement en ions nitrate des eaux sous jacentes. Cette étude a permis de préciser la participation de l'engrais à la pollution nitrique à hauteur de 21% et de souligner toute l'importance de l'immobilisation microbienne des engrais par le sol. Enfin, sous conditions contrôlées, nous montrons les variations de l'immobilisation des engrais apportés et surtout de leur cinétique de reminéralisation en fonction du pédoclimat

Characterization of Dicer-deficient murine embryonic stem cells

Dicer is an RNase III-family nuclease that initiates RNA interference (RNAi) and related phenomena by generation of the small RNAs that determine the specificity of these gene silencing pathways. We have previously shown that Dicer is essential for mammalian development, with Dicer-deficient mice dying at embryonic day 7.5 with a lack of detectable multipotent stem cells. To permit a more detailed investigation of the biological roles of Dicer, we have generated embryonic stem cell lines in which their single Dicer gene can be conditionally inactivated. As expected, Dicer loss compromises maturation of microRNAs and leads to a defect in gene silencing triggered by long dsRNAs. However, the absence of Dicer does not affect the ability of small interfering RNAs to repress gene expression. Of interest, Dicer loss does compromise the proliferation of ES cells, possibly rationalizing the phenotype previously observed in Dicer-null animals. Dicer loss also affects the abundance of transcripts from mammalian centromeres but does so without a pronounced affect on histone modification status at pericentric repeats or methylation of centromeric DNA. These studies provide a conditional model of RNAi deficiency in mammals that will permit the dissection of the biological roles of the RNAi machinery in cultured mammalian cells

Analyzing the effectiveness of the bank credit channel in transmitting the impact of monetary policy on the Algerian economy using Toda Yamamoto's methodology during the period 1990-2019

حاولت هذه الدراسة البحث في مدى فعالية قناة الائتمان المصرفي في نقل آثار السياسة النقدية إلى كل من التضخم والنمو الاقتصادي في الأجل الطويل، باستخدام اختبار السببية لـ Toda-Yamamoto وباستخدام بيانات سنوية للمتغيرات سعر إعادة الخصم، الائتمان المصرفي المقدم للاقتصاد، التضخم والنمو الاقتصادي خلال الفترة 1990-2019، حيث توصلت الدراسة إلى نتائج مفادها فعالية قناة الائتمان المصرفي في نقل أثار السياسة النقدية إلى التضخم وذلك لوجود علاقة سببية من سعر إعادة الخصم ومن الائتمان المصرفي إلى التضخم وعدم فعالية هاته القناة في نقل آثار السياسة النقدية إلى النمو الاقتصادي بسبب غياب العلاقة السببية طويلة الأجل بين سعر إعادة الخصم والنمو الاقتصادي.This study attempted to investigate the effectiveness of the bank credit channel in transmitting the effects of monetary policy to both inflation and economic growth in the long term, Using the Toda-Yamamoto causality test And by using annual data for variables re-discount rate, bank credit, inflation and economic growth during the period 1990-2019, The study concluded that the effectiveness of the bank credit channel in transmitting the effects of monetary policy to inflation This is due to the existence of a causal relationship from the discount rate and from bank credit to inflation, and the ineffectiveness of this channel in transmitting the effects of monetary policy to economic growth due to the absence of a long-term causal relationship between the discount rate and economic growth

The histone chaperone CAF-1 safeguards somatic cell identity

Cellular differentiation involves profound remodelling of chromatic landscapes, yet the mechanisms by which somatic cell identity is subsequently maintained remain incompletely understood. To further elucidate regulatory pathways that safeguard the somatic state, we performed two comprehensive RNA interference (RNAi) screens targeting chromatin factors during transcription-factor-mediated reprogramming of mouse fibroblasts to induced pluripotent stem cells (iPS cells). Subunits of the chromatin assembly factor-1 (CAF-1) complex, including Chaf1a and Chaf1b, emerged as the most prominent hits from both screens, followed by modulators of lysine sumoylation and heterochromatin maintenance. Optimal modulation of both CAF-1 and transcription factor levels increased reprogramming efficiency by several orders of magnitude and facilitated iPS cell formation in as little as 4 days. Mechanistically, CAF-1 suppression led to a more accessible chromatin structure at enhancer elements early during reprogramming. These changes were accompanied by a decrease in somatic heterochromatin domains, increased binding of Sox2 to pluripotency-specific targets and activation of associated genes. Notably, suppression of CAF-1 also enhanced the direct conversion of B cells into macrophages and fibroblasts into neurons. Together, our findings reveal the histone chaperone CAF-1 to be a novel regulator of somatic cell identity during transcription-factor-induced cell-fate transitions and provide a potential strategy to modulate cellular plasticity in a regenerative setting

Control of a neuronal morphology program by an RNA-binding zinc finger protein, Unkempt

Cellular morphology is an essential determinant of cellular function in all kingdoms of life, yet little is known about how cell shape is controlled. Here we describe a molecular program that controls the early morphology of neurons through a metazoan-specific zinc finger protein, Unkempt. Depletion of Unkempt in mouse embryos disrupts the shape of migrating neurons, while ectopic expression confers neuronal-like morphology to cells of different nonneuronal lineages. We found that Unkempt is a sequence-specific RNA-binding protein and identified its precise binding sites within coding regions of mRNAs linked to protein metabolism and trafficking. RNA binding is required for Unkempt-induced remodeling of cellular shape and is directly coupled to a reduced production of the encoded proteins. These findings link post-transcriptional regulation of gene expression with cellular shape and have general implications for the development and disease of multicellular organisms

The chromatin assembly factor complex 1 (CAF1) and 5-Azacytidine (5-AzaC) affect cell motility in Src-transformed human epithelial cells

Tumor invasion into surrounding stromal tissue is a hallmark of high grade, metastatic cancers. Oncogenic transformation of human epithelial cells in culture can be triggered by activation of v-Src kinase, resulting in increased cell motility, invasiveness, and tumorigenicity and provides a valuable model for studying how changes in gene expression cause cancer phenotypes. Here, we show that epithelial cells transformed by activated Src show increased levels of DNA methylation and that the methylation inhibitor 5-azacytidine (5-AzaC) potently blocks the increased cell motility and invasiveness induced by Src activation. A proteomic screen for chromatin regulators acting downstream of activated Src identified the replication-dependent histone chaperone CAF1 as an important factor for Src-mediated increased cell motility and invasion. We show that Src causes a 5-AzaC-sensitive decrease in both mRNA and protein levels of the p150 (CHAF1A) and p60 (CHAF1B), subunits of CAF1. Depletion of CAF1 in untransformed epithelial cells using siRNA was sufficient to recapitulate the increased motility and invasive phenotypes characteristic of transformed cells without activation of Src. Maintaining high levels of CAF1 by exogenous expression suppressed the increased cell motility and invasiveness phenotypes when Src was activated. These data identify a critical role of CAF1 in the dysregulation of cell invasion and motility phenotypes seen in transformed cells and also highlight an important role for epigenetic remodeling through DNA methylation for Src-mediated induction of cancer phenotypes

Deep sequencing of small RNAs identifies canonical and non-canonical miRNA and endogenous siRNAs in mammalian somatic tissues

MicroRNAs (miRNAs) are small RNA molecules that regulate gene expression. They are characterized by specific maturation processes defined by canonical and non-canonical biogenic pathways. Analysis of ∼0.5 billion sequences from mouse data sets derived from different tissues, developmental stages and cell types, partly characterized by either ablation or mutation of the main proteins belonging to miRNA processor complexes, reveals 66 high-confidence new genomic loci coding for miRNAs that could be processed in a canonical or non-canonical manner. A proportion of the newly discovered miRNAs comprises mirtrons, for which we define a new sub-class. Notably, some of these newly discovered miRNAs are generated from untranslated and open reading frames of coding genes, and we experimentally validate these. We also show that many annotated miRNAs do not present miRNA-like features, as they are neither processed by known processing complexes nor loaded on AGO2; this indicates that the current miRNA miRBase database list should be refined and re-defined. Accordingly, a group of them map on ribosomal RNA molecules, whereas others cannot undergo genuine miRNA biogenesis. Notably, a group of annotated miRNAs are Dgcr8 independent and DICER dependent endogenous small interfering RNAs that derive from a unique hairpin formed from a short interspersed nuclear element

The biogenesis and characterization of mammalian microRNAs of mirtron origin

Mirtrons, short hairpin pre-microRNA (miRNA) mimics directly produced by intronic splicing, have recently been identified and experimentally confirmed in invertebrates. While there is evidence to suggest several mammalian miRNAs have mirtron origins, this has yet to be experimentally demonstrated. Here, we characterize the biogenesis of mammalian mirtrons by ectopic expression of splicing-dependent mirtron precursors. The putative mirtrons hsa-miR-877, hsa-miR-1226 and mmu-miR-1224 were designed as introns within eGFP. Correct splicing and function of these sequences as introns was shown through eGFP fluorescence and RT–PCR, while all mirtrons suppressed perfectly complementary luciferase reporter targets to levels similar to that of corresponding independently expressed pre-miRNA controls. Splicing-deficient mutants and disruption of key steps in miRNA biogenesis demonstrated that mirtron-mediated gene knockdown was splicing-dependent, Drosha-independent and had variable dependence on RNAi pathway elements following pre-miRNA formation. The silencing effect of hsa-miR-877 was further demonstrated to be mediated by the generation of short anti-sense RNA species expressed with low abundance. Finally, the mammalian mirtron hsa-miR-877 was shown to reduce mRNA levels of an endogenous transcript containing hsa-miR-877 target sites in neuronal SH-SY5Y cells. This work confirms the mirtron origins of three mammalian miRNAs and suggests that they are a functional class of splicing-dependent miRNAs which are physiologically active

Sustained miRNA-mediated Knockdown of Mutant AAT With Simultaneous Augmentation of Wild-type AAT Has Minimal Effect on Global Liver miRNA Profiles

α-1 antitrypsin (AAT) deficiency can exhibit two pathologic states: a lung disease that is primarily due to the loss of AAT's antiprotease function, and a liver disease resulting from a toxic gain-of-function of the PiZ-AAT (Z-AAT) mutant protein. We have developed several recombinant adeno-associated virus (rAAV) vectors that incorporate microRNA (miRNA) sequences targeting the AAT gene while also driving the expression of miRNA-resistant wild-type AAT-PiM (M-AAT) gene, thus achieving concomitant Z-AAT knockdown in the liver and increased expression of M-AAT. Transgenic mice expressing the human PiZ allele treated with dual-function rAAV9 vectors showed that serum PiZ was stably and persistently reduced by an average of 80%. Treated animals showed knockdown of Z-AAT in liver and serum with concomitant increased serum M-AAT as determined by allele-specific enzyme-linked immunosorbent assays (ELISAs). In addition, decreased globular accumulation of misfolded Z-AAT in hepatocytes and a reduction in inflammatory infiltrates in the liver was observed. Results from microarray studies demonstrate that endogenous miRNAs were minimally affected by this treatment. These data suggests that miRNA mediated knockdown does not saturate the miRNA pathway as has been seen with viral vector expression of short hairpin RNAs (shRNAs). This safe dual-therapy approach can be applied to other disorders such as amyotrophic lateral sclerosis, Huntington disease, cerebral ataxia, and optic atrophies