18 research outputs found
A Novel fry1 Allele Reveals the Existence of a Mutant Phenotype Unrelated to 5âČ->3âČ Exoribonuclease (XRN) Activities in Arabidopsis thaliana Roots
BACKGROUND Mutations in the FRY1/SAL1 Arabidopsis locus are highly pleiotropic, affecting drought tolerance, leaf shape and root growth. FRY1 encodes a nucleotide phosphatase that in vitro has inositol polyphosphate 1-phosphatase and 3',(2'),5'-bisphosphate nucleotide phosphatase activities. It is not clear which activity mediates each of the diverse biological functions of FRY1 in planta. PRINCIPAL FINDINGS A fry1 mutant was identified in a genetic screen for Arabidopsis mutants deregulated in the expression of Pi High affinity Transporter 1;4 (PHT1;4). Histological analysis revealed that, in roots, FRY1 expression was restricted to the stele and meristems. The fry1 mutant displayed an altered root architecture phenotype and an increased drought tolerance. All of the phenotypes analyzed were complemented with the AHL gene encoding a protein that converts 3'-polyadenosine 5'-phosphate (PAP) into AMP and Pi. PAP is known to inhibit exoribonucleases (XRN) in vitro. Accordingly, an xrn triple mutant with mutations in all three XRNs shared the fry1 drought tolerance and root architecture phenotypes. Interestingly these two traits were also complemented by grafting, revealing that drought tolerance was primarily conferred by the rosette and that the root architecture can be complemented by long-distance regulation derived from leaves. By contrast, PHT1 expression was not altered in xrn mutants or in grafting experiments. Thus, PHT1 up-regulation probably resulted from a local depletion of Pi in the fry1 stele. This hypothesis is supported by the identification of other genes modulated by Pi deficiency in the stele, which are found induced in a fry1 background. CONCLUSIONS/SIGNIFICANCE Our results indicate that the 3',(2'),5'-bisphosphate nucleotide phosphatase activity of FRY1 is involved in long-distance as well as local regulatory activities in roots. The local up-regulation of PHT1 genes transcription in roots likely results from local depletion of Pi and is independent of the XRNs.This work was supported by an ANR-GENOPLANT grant (RIBOROOT-ANR06 GPLA 011) and the CEA agency. Array hybridizations have been partly supported by RNG (RĂ©seau National des GĂ©nopoles, Evry, France). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No additional external funding received for this study
A Novel fry1 Allele Reveals the Existence of a Mutant Phenotype Unrelated to 5âČ->3âČ Exoribonuclease (XRN) Activities in Arabidopsis thaliana Roots
International audienceBackgroundMutations in the FRY1/SAL1 Arabidopsis locus are highly pleiotropic, affecting drought tolerance, leaf shape and root growth. FRY1 encodes a nucleotide phosphatase that in vitro has inositol polyphosphate 1-phosphatase and 3âČ,(2âČ),5âČ-bisphosphate nucleotide phosphatase activities. It is not clear which activity mediates each of the diverse biological functions of FRY1 in planta.Principal FindingsA fry1 mutant was identified in a genetic screen for Arabidopsis mutants deregulated in the expression of Pi High affinity Transporter 1;4 (PHT1;4). Histological analysis revealed that, in roots, FRY1 expression was restricted to the stele and meristems. The fry1 mutant displayed an altered root architecture phenotype and an increased drought tolerance. All of the phenotypes analyzed were complemented with the AHL gene encoding a protein that converts 3âČ-polyadenosine 5âČ-phosphate (PAP) into AMP and Pi. PAP is known to inhibit exoribonucleases (XRN) in vitro. Accordingly, an xrn triple mutant with mutations in all three XRNs shared the fry1 drought tolerance and root architecture phenotypes. Interestingly these two traits were also complemented by grafting, revealing that drought tolerance was primarily conferred by the rosette and that the root architecture can be complemented by long-distance regulation derived from leaves. By contrast, PHT1 expression was not altered in xrn mutants or in grafting experiments. Thus, PHT1 up-regulation probably resulted from a local depletion of Pi in the fry1 stele. This hypothesis is supported by the identification of other genes modulated by Pi deficiency in the stele, which are found induced in a fry1 background.Conclusions/SignificanceOur results indicate that the 3âČ,(2âČ),5âČ-bisphosphate nucleotide phosphatase activity of FRY1 is involved in long-distance as well as local regulatory activities in roots. The local up-regulation of PHT1 genes transcription in roots likely results from local depletion of Pi and is independent of the XRNs.
Corrélation entre la dynamique de la population de Myodes glareolus et la prévalence de l'hantavirus Puumala
Zoonotic diseases have always been a major concern on the global economy and public health. To limit at best of their expansion, many programs are launched to prevent, monitor and fight against these diseases. Edenext program's mission is to study some hantaviruses, which cause hemorrhagic fever with renal syndrome to humans. To understand the persistence and the circulation of infectious agents, one must initially know the role and the functioning of animal reservoirs. We were interested in Puumala hantavirus and its host, the bank vole Myodes' glareolus. Our hypothesis was that the local prevalence of Puumala hantavirus (PUUV) is related to the population dynamics of voles. We tested this hypothesis by relying on some genetic parameters, the allelique richness (A) and the genetic divergence (FST) that are used as surrogates for inferring the population dynamics of voles. Thus, low A values and high FST values indicate that populations are small sized and isolated with others, whereas high A values and low FST values are indicative of large populations well connected with others. The study area is located in Belgian Flanders. This region is characterized by a low prevalence of hantaviruses and highly fragmented landscape, which consists of isolated groves and edge networks. We studied 375 voles caught in Fall 2004 in 15 localities. Genetic composition was measured with 19 microsatellite loci. We found that despite a low overall prevalence, it was higher or lower depending on the characteristics of the landscape. Indeed, we found that PUUV prevalence, although low in general, was highly correlated with allelic richness, with high prevalence in large populations (A values high) and low prevalence in small and isolated populations (A values small). Comparison with other works shows that this observation can be generalized to other geographic regions (Finland and France) and other types of landscapes (large boreal and temperate forests) characterized by high prevalence of Puumala hantavirus. Our work opens up new avenues of understanding of the factors limiting the geographic distribution of this virus in Western Europe.!Les zoonoses reprĂ©sentent un problĂšme majeur depuis toujours sur lâĂ©conomie mondiale et la santĂ© publique. Pour limiter au mieux leur expansion, de nombreux programmes de recherche sont lancĂ©s en vue de prĂ©venir, surveiller et lutter contre ces maladies. Le programme Edenext a pour mission dâĂ©tudier certains hantavirus qui provoquent des fiĂšvres hĂ©morragiques Ă syndrome rĂ©nal chez lâhomme. Pour comprendre la persistance et la circulation des agents infectieux, il faut dans un premier temps connaĂźtre le rĂŽle et le fonctionnement des animaux rĂ©servoirs. Nous nous sommes intĂ©ressĂ©s Ă lâhantavirus Puumala et Ă son hĂŽte, le campagnol roussĂątre Myodes'glareolus.'Notre hypothĂšse Ă©tait que la dynamique des populations du campagnol dĂ©termine la prĂ©valence de lâhantavirus. Nous avons testĂ© cette hypothĂšse en nous appuyant sur des paramĂštres gĂ©nĂ©tiques, la richesse allĂ©lique (A) et de lâisolement gĂ©nĂ©tique (FST), qui donnent une mesure indirecte de la dynamique des populations des campagnols. Ainsi, lorsque A est faible et FST Ă©levĂ©, cela sous entend que la population est de petite taille et isolĂ©e (peu ou pas de liaison avec les autres populations). Dans le cas contraire (A fort et FST faible) câest une population de grande taille et avec une grande connectivitĂ© avec dâautres populations. La zone dâĂ©tude se situe dans la Flandre belge. Cette rĂ©gion est caractĂ©risĂ©e par une faible prĂ©valence Ă lâhantavirus et par un paysage forestier fragmentĂ©, composĂ© de bosquets et de rĂ©seaux de haies assez isolĂ©s. Au total nous avons travaillĂ© sur 375 animaux capturĂ©s Ă lâAutomne 2004 dans 15 sites dâĂ©tude. La diversitĂ© gĂ©nĂ©tique a Ă©tĂ© mesurĂ©e Ă lâaide de 19 marqueurs microsatellites. LâĂ©tude a rĂ©vĂ©lĂ© que la prĂ©valence, bien que faible en gĂ©nĂ©ral, Ă©tait trĂšs corrĂ©lĂ©e aux paramĂštres gĂ©nĂ©tiques, en particulier Ă la diversitĂ© gĂ©nĂ©tique (A) : prĂ©valence Ă©levĂ©e dans les grandes populations bien connectĂ©es aux autres (A Ă©levĂ©) et faible dans les petites populations isolĂ©es (A faible). La comparaison avec dâautres travaux rĂ©vĂšle que cette observation peut ĂȘtre gĂ©nĂ©ralisĂ©e Ă dâautres rĂ©gions gĂ©ographiques (Finlande et France) et dans dâautre type de paysages (grands massifs forestiers borĂ©als et tempĂ©rĂ©s) caractĂ©risĂ©s par de fortes prĂ©valences dâhantavirus Puumala, Ce travail ouvre des voies de comprĂ©hension sur les facteurs qui limitent la distribution gĂ©ographique de ce virus en Europe de lâOuest
Glucose-galactose transporter DEFICIENCY: a diagnosis based on clinical observations.
Dehydration and major diarrhea in young infants is mainly linked to infectious diseases. However in case leading to denutrition and growth retardation, metabolic causes or malabsorption should be evocated. We report here the case of a few days old infant admitted for early recurrence of liquid stools and vomiting.
XX is born at term (3450 grams, 51 cm) after an uneventful pregnancy. Consanguinity has been reported in the family. He was breastfed but presented rapidly liquid stools and vomiting. At 10 days old he was first admitted for dehydration, loss of weight below his birth weight (2900 grams) and severe hypernatremia. Semi elementary diet led to some improvement but he was readmitted at the age of one month for similar even worse symptoms including abdominal distension and explosive stools. Complementary investigations have excluded infection, parasitosis, malformation and immune deficits. Different diet formulas were tried with no significant benefit what led to the placement of parenteral nutrition thanks to which weight was gained. Hypothesis of peculiar carbohydrate malabsorption was made and the following tests have been carried out:
-Clinitest: presence of reducing substances in the stools.
-Lactose Breath test: between 15 and 90 ppm H2 with a peak value at 90 ppm H2 after 90 minutes.
-Duodenal biopsy: normal histology; normal activity of lactase, maltase, saccharase-isomaltase.
Considering the normality of these enzyme activities, hypothesis of âNa-dependant glucose-galactose transporterâ deficit was put forward. This was confirmed according to the results of HGPO and glucose breath test. Search for SGTL1 gene mutation is still in progress.
In conclusion despite of the huge progresses made at molecular biology level, clinical observation remain essential to the diagnosis of malabsorption. Precise reporting of the used milk formula and comparative analysis of their composition can orient the diagnosis and help to select the most accurate molecular test. Here, analyses exclude every enzyme activity deficiencies. Carbohydrate malabsorption from first days of live can be linked to a glucose-galactose transporter deficiency due to a SGLT1 mutation (chr 22). This autosomal recessive disorder has only been reported 200 times until now
Corrélation phénotype-génotype chez les enfants atteints de neurofibromatose de type 1
AbstractNeurofibromatosis type 1 (NF1) is a common autosomal dominant disorder with an incidence of âŒ1 in 4,000 live births. Neurofibromin, the gene product, is ubiquitously expressed at high levels in the nervous system and functions as a tumor suppressor. Haploinsufficiency of neurofibromin through mutation leads to an increased risk of developing benign and malignant tumors in affected individuals. Although NF1 has complete penetrance, it displays considerable inter- and intrafamilial variability in phenotypic expression which poses disease prediction and management problems. Some NF1 genotypeâphenotype correlations have been described. To evaluate the genetic component of variable expressivity in NF1, we examined the phenotypic correlations between affected relatives in 52 NF1 patients from 45 families.</jats:p
à propos de deux cas de méningococcémie. Revue de la littérature sur la méningococcémie chronique
Introduction : Neisseria meningitidis est une bactĂ©rie commensale responsable dâinfections invasives rares graves, potentiellement mortelles. Dans certains cas, elle est Ă lâorigine de formes atypiques de septicĂ©mies aiguĂ«s, subaiguĂ«s ou chroniques qui, bien que souvent dâĂ©volution plus lente, font encourir les mĂȘmes risques aux patients.
Observation : Le patient 1 prĂ©sentait une fiĂšvre rĂ©currente, des polyarthralgies et une Ă©ruption maculaire gĂ©nĂ©ralisĂ©e. Le patient 2 prĂ©sentait une fiĂšvre modĂ©rĂ©e depuis 10 jours, des douleurs cervicales postĂ©rieures et une Ă©ruption maculaire. Les hĂ©mocultures des deux patients ont permis de confirmer la prĂ©sence dâun mĂ©ningocoque du groupe B. Lâamplification gĂ©nique (PCR) sur le liquide cĂ©phalorachidien (LCR) du patient 2 Ă©tait Ă©galement positive pour le mĂȘme germe, alors que la culture Ă©tait stĂ©rile. LâĂ©volution sous antibiothĂ©rapie a Ă©tĂ© favorable.
Discussion : La mĂ©ningococcĂ©mie chronique se caractĂ©rise par une triade clinique, comprenant une fiĂšvre prolongĂ©e, des arthralgies et une Ă©ruption. LâĂ©volution est favorable sans sĂ©quelles si la prise en charge est adĂ©quate. La PCR sur LCR, les hĂ©mocultures et la culture du LCR se rĂ©vĂšlent des outils complĂ©mentaires pour confirmer le diagnostic.
Conclusion : Lâinfection Ă mĂ©ningocoque peut se manifester de façons trĂšs diffĂ©rentes. Le diagnostic de mĂ©ningococcĂ©mie chronique doit ĂȘtre Ă©voquĂ© devant une triade associant fiĂšvre prolongĂ©e, Ă©ruption et arthralgies, et le germe activement recherchĂ© par des techniques comme la PCR, surtout quand la culture du LCR est stĂ©rile.[Two case reports of meningococcemia. Review of the literature on chronic meningococcemia]. INTRODUCTION: Neisseria meningitidis is a Gram-negative bacteria that can be highly pathogenic in humans and responsible for life-threatening and acute diseases. In a few cases, it can lead to an atypical form of sepsis-acute, subacute, or chronic-which, even if progression is slower, may carry the same risks for patients as conventional acute forms.
CASES: Case 1 presented with recurrent fever, polyarthralgia, and generalized macular rash. Case 2 had fever for the previous 10days with neck pain and macular rash. Blood cultures were positive for group B meningococcus in both cases. Polymerase chain reaction (PCR) analysis for the same pathogen was also positive in the cerebrospinal fluid (CSF) of Case 2. Following intravenous antibiotic treatment, the progression was favorable in both cases.
DISCUSSION: Chronic meningococcemia is characterized by a triad of clinical features, including a fever lasting for at least 1week, arthralgia, and a cutaneous rash. This condition evolves positively without any sequelae if treated properly. PCR and blood culture are two complimentary tools that support the diagnosis.
CONCLUSION: Meningococcal infection can manifest in a variety of ways. Chronic meningococcemia diagnosis should be considered in a triad of prolonged fever, rash, and arthralgia. Better access to state-of-the-art techniques such as PCR is recommended in the future so as to provide optimal care of patients suffering from this condition
DĂ©crochage de la courbe de pĂ©rimĂštre crĂąnien et si lâorigine n'Ă©tait pas neurologique
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