Junctional Epidermolysis Bullosa in the German shorthaired pointer: a spontaneous model for Junctional Epidermolysis Bullosa in man

A Junctional Epidermolysis Bullosa (JEB), described in the German shorthaired pointer, is a remarkable spontaneous canine model for Junctional Epidermolysis Bullosa in man. In the German shorthaired pointer, JEB is caused by a homozygous substitution of the 1514C-T nucleotide. This variation in sequence results in a non-conservative change of 14 amino acids (505T –I) in domain I of laminin-5 α3. This non-conservative substitution modifies the hydrophobicity profile of the peptidic fragment, and therefore alters the stability of the binding between the α3 chain and the β3γ2 heterotrimer, which could result in a breakdown of the muted polypeptide. A fraction of muted α3 could be incorporated in laminin-5, modifying its function and hindering the extracellular cleavage of the γ2 chain. Genetic complementation studies were carried out. An MMLV retrovirus expressing the whole cDNA, muted and wild, of the α3 chain was developed to be transducted in the keratinocytes of JEB dogs (KJEB). This phenotypic transversion was successful and brought back a3 chain secretion, and thus the production of functional laminin-5 molecules. In addition, the adhesion capabilities of these transducted KJEB in cultures also returned. Finally, the reconstitution of canine JEB epithelia expressing a hybrid laminin-5 is now possible, and is currently used in studies on the fate of these ex vivo grafts in JEB dogs.Une Epidermolyse Bulleuse Jonctionnelle (EBJ) est décrite chez le Braque allemand et constitue un remarquable modèle canin de l'épidermolyse bulleuse jonctionnelle de l'Homme. Chez le Braque allemand, cette maladie est causée par une substitution homozygote du nucléotide 1514 C-T chez les chiens EBJ. Cette variation de séquence induit un changement non conservatif de 14 acides aminés (505T-I) dans le domaine I de la laminine a3. Cette substitution non conservative modifie le profil d'hydrophobicité du fragment peptidique et altère donc la stabilité d'association de la chaîne a3 avec l'hétérotrimère β3γ2. Ceci pourrait aboutir à une dégradation du polypeptide muté. Une fraction d'a3 mutée pourrait s'incorporer dans la laminine 5, en altérer le fonctionnement et entraver le clivage extra-cellulaire de la chaîne y2. Des expériences de complémentation génétique ont donc été réalisées. Pour cela, un rétrovirus MMLV exprimant l'ADNc entier muté et sauvage de la chaîne a3 a été construit pour être transduit dans les kératinocytes des chiens EBJ (KEBJ). Cette transversion phénotypique a été réussie et a permis aux KEBJ de sécréter de nouveau la chaîne a3 et ainsi, de produire des molécules de laminine 5 fonctionnelles. Par ailleurs, ces KEBJ transduits ont montré aussi la restauration de leur capacité d'adhésion en culture. Enfin, la reconstitution d'épithéliums canins EBJ exprimant une laminine 5 hybride est désormais possible et actuellement à l'origine d'études sur le devenir de ces greffes ex vivo chez des chiens atteints d'EBJ

Informazioni diffuse e strumenti per la progettazione e gestione dell'ambiente costruito

Il paragrafo si inserisce all'interno del capitolo "Dati, informazioni, conoscenza per il progetto" e tratta i seguenti temi: Piattaforme informative e informazioni diffuse: i Living Lab; Big data e Internet of Things per una gestione intelligente dell’edificio; L’interazione tra i dati qualitativi e i dati quantitativi per la valutazione della qualità dell’ambiente costruito; Dalla rilevazione del feedback dell’utenza all’interazione con dati quantitativi (Post Occupancy Evaluation e Building Performance Evaluation); Sviluppi futuri e la necessità di nuove figure professionali

Informazioni diffuse e strumenti per la progettazione e gestione dell’ambiente costruito

Il paragrafo si inserisce all'interno del capitolo "Dati, informazioni, conoscenza per il progetto" e tratta i seguenti temi: Piattaforme informative e informazioni diffuse: i Living Lab; Big data e Internet of Things per una gestione intelligente dell’edificio; L’interazione tra i dati qualitativi e i dati quantitativi per la valutazione della qualità dell’ambiente costruito; Dalla rilevazione del feedback dell’utenza all’interazione con dati quantitativi (Post Occupancy Evaluation e Building Performance Evaluation); Sviluppi futuri e la necessità di nuove figure professionali

Il MUSES / Museo della Scienza e del Suolo

L’ipotesi del MUSeS – Museo della Scienza e del Suolo nel comparto di via Guido Reni si pone l’obiettivo di formulare una proposta ex novo in cui, attraverso una serie di operazioni consequenziali - sia dal punto di vista progettuale, sia dal punto di vista cronologico - si vuole cercare una connessione stretta fra le preesistenze di questo ambito del quartiere Flaminio, il sistema delle volumetrie del progetto di Paola Viganò et al. per le ex Caserme di via Guido Reni e il prospiciente MaXXI. Una grande piastra di 100x100 m dall’involucro traslucido, in un policarbonato diafano tradito da poche e proporzionate aperture in vetro, viene posizionata su un sistema di appoggi che rimarca, nell’impronta a terra e nelle volumetrie complessive, il segno sul tessuto urbano impresso dai costituendi edifici residenziali del progetto vincitore del concorso 2015

RNA polymerase (rpoB) mutants selected for increased resistance to gyrase inhibitors in Salmonella typhimurium

International audienceSome rifampicin-resistance (RifR) mutations make bacteria slightly resistant to the gyrase inhibitors novobiocin (Nov) and nalidixic acid (Nal). This suggested that it might be possible to isolate rpoB mutants using either drug for positive selection. In an initial test, we confirmed the presence of Rif-resistant isolates among clones selected for Nov resistance. These mutants are also more resistant to Nal. In a subsequent experiment, we found that mutants selected for low-level resistance to Nal include isolates harboring mutations genetically linked to the rpoB locus; of two such mutants studied, one is temperature-sensitive for growth. These two mutants, which are only marginally affected in their response to Nov, are normally sensitive to Rif and thus might be representative of a new class of rpoB alleles. The Rif-resistant and Rif-sensitive rpoB alleles that increase resistance to gyrase inhibitors have one property in common: they all suppress, to varying degrees, the defect in his operon regulation (transcriptional deattenuation) caused by a gyrase defect or inhibition by novobiocin. To further analyse the transcription-supercoiling relationships in these mutants, we examined the ability of RNA polymerase to recruit gyrase activity during transcription. This was done by two independent approaches: (i) observing transcription-induced accumulation of hyper-negatively supercoiled plasmid DNA in a topA mutant background and (ii) measuring transcription-induced plasmid DNA cleavage in the presence of oxolinic acid. Results indicate that the rpoB alleles described in this study diminish the recruitment of gyrase activity by the transcription process. This property correlates with a decrease in the rate of transcription initiation.(ABSTRACT TRUNCATED AT 250 WORDS

A class of gyrase mutants of Salmonella typhimurium show quinolone‐like lethality and require Rec functions for viability

International audienceWe have identified a new class of DNA gyrase mutants of Salmonella typhimurium that show chronic derepression of the SOS regulon. Thus, these mutants mimic the response of wild-type cells to gyrase inhibitors of the quinolone family. SOS induction by conditional lethal mutations gyrA208 or gyrB652, like that mediated by quinolones, is completely dependent on the function of the recB gene product. Introduction of recA or recB null mutations into these strains exacerbates their temperature-sensitive phenotype and prevents growth at the otherwise permissive temperature of 37 degrees C. Selection of suppressors that concomitantly restore growth at 37 degrees C and SOS induction in a recB- background yielded mutations that relleve the RecB requirement for homologous recombination; namely, sbcB mutations as well as mutations at a new locus that was named sbcE. Such mutations also restore SOS induction in quinolone-treated gyr+ recB- strains. These findings indicate that Rec functions are needed for growth of the gyrase mutants at 37 degrees C and suggest that recombinational repair intermediates constitute the SOS-inducing signal in the mutants as well as in quinolone-treated wild-type bacteria. Unlike quinolones, however, the gyr mutations described in this study do not cause detectable accumulation of "cleavable' gyrase-DNA complexes in plasmid or chromosomal DNA. Yet gyrA208 (the only allele tested) was found to trigger RecB-mediated reckless degradation of chromosomal DNA in recA-cells at restrictive temperatures. Indirect evidence suggests that double-stranded DNA ends, entry sites for the RecBCD enzyme, are generated in the gyr mutants by the breakage of DNA-replication forks. We discuss how this could occur and how recombinational rescue of collapsed replication forks could account for cell survival (and SOS induction) in the gyr mutants as well as in quinolone-treated bacteria