Dynamic removal of replication protein A by Dna2 facilitates primer cleavage during Okazaki fragment processing in Saccharomyces cerevisiae

Eukaryotic Okazaki fragments are initiated by an RNA/DNA primer, which is removed before the fragments are joined. Polymerase d displaces the primer into a flap for processing. Dna2 nuclease/helicase and flap endonuclease 1 (FEN1) are proposed to cleave the flap. The single-stranded DNA binding protein, replication protein A (RPA), governs cleavage activity. Flap-bound RPA inhibits FEN1. This necessitates cleavage by Dna2, which is stimulated by RPA. FEN1 then cuts the remaining RPA-free flap to create a nick for ligation. Cleavage by Dna2 requires that it enter the 5'-end and track down the flap. Since Dna2 cleaves the RPA-bound flap, we investigated the mechanism by which Dna2 accesses the protein-coated flap for cleavage. Using a nuclease-defective Dna2 mutant, we showed that just binding of Dna2 dissociates the flap-bound RPA. Facile dissociation is specific to substrates with a genuine flap, and will not occur with an RPA-coated single strand. We also compared the cleavage patterns of Dna2 with and without RPA to better define RPA stimulation of Dna2. Stimulation derived from removal of DNA folding in the flap. Apparently, coordinated with its dissociation, RPA relinquishes the flap to Dna2 for tracking in a way that does not allow flap structure to reform. We also found that RPA strand melting activity promotes excessive flap elongation, but it is suppressed by Dna2-promoted RPA dissociation. Overall, results indicate that Dna2 and RPA coordinate their functions for efficient flap cleavage and preparation for FEN1

Alone Together

Les bibliothèques – et les Archives – françaises se sont modernisées. Elles ont gagné en efficacité, mais peut-être perdu en « sociabilité », une notion centrale dans la culture anglo-saxonne. L’environnement matériel induit-il certaines pratiques de recherche ? Habituée de la BnF et des recherches en archives, une historienne américaine nous livre ses impressions à coeur ouvert

Preservice Generalist Teachers Enlightened Approach to Teaching Physical Education through Teacher Biography.

This paper describes a new learning experience, which was introduced following an examination of the literature regarding preservice primary school teachers’ (PPST) notions of their past experience in Physical Education (PE) (Elliott 2013). PPSTs were given the opportunity to recognise, reflect, interrogate and reframe a critical incident from their schooling in PE or Sport. This exercise was designed to enlighten students about their own schooling and the potential impact this event may have on pre-conceived ideas and opinions about teaching PE. Students (N=214) enrolled in off and on campus mode, of a preservice teacher education program in a university located in regional NSW, were asked to provide information about, and to analyse, an incident, either positive or negative that occurred in PE or Sport during their primary or secondary school years. In addition, students were encouraged to reframe the incident and to seek out alternative actions that could have influenced the outcome. The aim was to encourage reflection about how preconceived notions pertaining to PE might be dealt within their present position as a preservice teacher. The PPSTs scripts were analysed using the Leximancer text mining software (Smith, 2000). Findings from the analysis provided themes and concepts, which suggest a similarity for both, off and on campus, males and females. However, there are some subtle differences between the cohorts that may be due to an age or experience

Teacher Biography: SOLO Analysis of Preservice Teachers’ Reflections of their Experiences in Physical Education

Teacher biography, as a reflective practice, was implemented in the context of Physical Education in a primary teacher education course at a regional Australian university. Second year students were asked to provide descriptions of a critical incident they experienced at the primary or secondary level in a Physical Education or sporting context (N=214). Their responses comprised the data for this study and the Structure of Observed Learning Outcomes (SOLO) Model was used to determine the levels of complexity of the responses to ‘alternatives for action’ associated with these incidents. More responses were multistructural (48%), than relational (24%), and unistructural (23%), with extended abstract (3%) and the least, were prestructural (2%). The responses varied for gender and mode of enrolment (on or off campus). The findings that one third of students developed higher order (relational or extended abstract) responses challenge teacher educators to consider strategies to extend critical reflections

Des contrats sous tension : rétablir la propriété après la Terreur

Cet article étudie l’hyperinflation (1791-1797), qui éviscéra le patrimoine de la plupart des familles, et un remède à celle-ci, aussi inattendu que controversé : l’« action en rescision pour lésion d’outre-moitié ». Pendant que l’assignat tombait en-dessous d’1 % de sa valeur nominale, des familles affolées vendirent boutiques, maisons ou domaines afin de survivre à la crise. Souvent, ces propriétés furent cédées bien en-dessous de leur valeur, conduisant les hommes de loi à ressusciter cette procédure ancrée dans la loi romaine. Elle accordait aux vendeurs le droit de demander à leurs acheteurs une réévaluation du montant de la vente. Des débats enflammés secouèrent la société française et remirent en question plusieurs milliers de ventes, notamment après la loi du 19 floréal an VI. Les 531 actions trouvées dans les archives des Yvelines témoignent de la férocité avec laquelle les vendeurs poursuivirent leurs acheteurs. Au-delà de ces poursuites judiciaires, c’est la notion même de contrat qui était en débat : sa légitimité procède-t-elle de l’accord des volontés ou d’une mesure de l’équité ?This article treats the hyperinflation (1791-1797), « which eviscerated most families’ patrimony, and a remedy, as unexpected as it was controversial, the l’action en rescision pour lésion d’outre-moitié ». While the assignat fell to less than one per cent of its nominal value, terrified families sold off shops, homes and farms to survive the crisis. Often, these properties were sold for less than half their value, causing lawyers to revive these suits with their roots in Roman law. The law allowed sellers to sue buyers for more money to « repair » the inadequate amount in the sales contract. The fiery debates of the legislators shook French society and threw many thousands of sales into question. The law of 19 floréal VI reopened these suits and sellers seized on the possibilities that this legislation offered them. The 531 suits found in the archives of the Yvelines department attest to the ferocity with which sellers pursued their buyers. Far beyond these legal proceedings, this form of civil suit lay at the crossroads of discussions that animated the world of eighteenth-century jurists and that targeted key elements of any legitimate contract: Was it the « meeting of minds » or equity that rendered a contract legitimate? These suits, then, illuminate not only the shocking upheaval of the hyperinflation, but also the polemics that accompanied the development of the modern contract

Gender differences in renal responses to hyperglycemia and angiotensin-converting enzyme inhibition in diabetes

Gender differences in renal responses to hyperglycemia and angiotensin-converting enzyme inhibition in diabetes.BackgroundDiabetes mellitus reduces female gender-mediated protection against progression of renal disease but the mechanisms responsible for this loss of protection are unknown. The impact of gender on the diabetic hyperfiltration state has not previously been studied. Since hyperfiltration is a factor in the development of diabetic renal disease, and is influenced by hyperglycemia and renin-angiotensin system (RAS) blockade, we examined gender differences in the renal response to hyperglycemia and angiotensin-converting enzyme (ACE) inhibition in young males and females with uncomplicated type 1 diabetes mellitus.MethodsTen male and 12 female normoalbuminuric, normotensive, adolescents with type 1 diabetes mellitus were studied before ACE inhibition during clamped euglycemia and hyperglycemia, and then after 21 days treatment with enalapril (0.1 mg/kg daily × 1 week and then 0.1 mg/kg twice a day × 2 weeks).ResultsDuring clamped euglycemia, males exhibited significantly higher effective renal plasma flow (ERPF) and renal blood flow (RBF) and a lower renal vascular resistance (RVR). During clamped hyperglycemia, females exhibited reductions in ERPF and RBF, and increased RVR and filtration fraction (FF). Males exhibited no significant renal hemodynamic changes during hyperglycemia. After ACE inhibition treatment, both genders exhibited significant declines in arterial pressure, but only females displayed a reduction in glomerular filtration rate (GFR) and FF.ConclusionThe renal responses to hyperglycemia and ACE inhibition appear to differ between male and female adolescents with uncomplicated type 1 diabetes mellitus. Hyperglycemia-induced changes in RVR and FF in women may account, at least in part, for the loss of gender-based protection in diabetic renal disease

Immunogenicity ofEscherichia coli O antigen in upper urinary tract infection

Immunogenicity ofEscherichia coli O antigen in upper urinary tract infection. The role of immunogenicity of the infecting organism (Escherichia coli) in the antibody response to O antigen in upper urinary tract infection was investigated Heat-killed vaccines were prepared from “immunogenic” organisms which had produced upper urinary tract infection associated with high titers of hemag-glutinating antibody to O antigen and “nonimmunogenic” organisms which had produced upper urinary tract infection without a rise in antibody titer. “Immunogenic” 06 vaccine produced high titers of antibody in patients regarded as possibly “poor producers” of antibody, but “nonimmunogenic” 011 vaccine was not associated with a rise in titer in patients previously regarded as “good producers”. These vaccines were significantly different in immunogenicity (P < 0.05). Five vaccines were tested in 50 rats. The difference in hemagglutinating titers to O antigen between 06 and 011 was highly significant (P < 0.001). Immunogenicity of the infecting organism appears to be a significant factor in determining antibody response to O antigen in upper urinary tract infection.Immunogénicité de l'antigène O d'Escherichia coli dans les infections du haut appareil urinaire. Le rôle de l'immunogénicité de l'organisme infectant (Escherichia coli) dans la réponse immune à l'antigène O au cours des infections du haut appareil urinaire a été étudié. Des vaccins tués par la chaleur ont été préparés à partir d'organismes “immunogéniques” qui ont été responsables d'infection du haut appareil urinaire associées à des titres élevés d'anticorps hémagglutinants contre l'antigène O et d'organismes “non immunogéniques” qui ont produit une infection du haut appareil sans augmentation du titre d'anticorps. Le vaccin “immunogénique” 06 produit des titres élevés d'anticorps chez des malades considérés comme de faibles producteurs d'anticorps et le vaccin “non immunogénique” 011 ne détermine pas d'augmentation du titre chez des malades antérieurement considérés comme de “bons producteurs”. Ces vaccins diffèrent significativement en “immunogénicité” (P < 0, 05). Cinq vaccins ont été essayés chez 50 rats. La différence dans les titres d'hémmaglutination vis à vis de l'antigène O est très significative entre 06 et 011 (P < 0, 001). L'immunogénicité de l'organisme infectant parait être un facteur important dans la détermination de la réponse immune à l'antigène O au cours des infections du haut appareil urinaire