Enhanced Fusion Pore Expansion Mediated by the Trans-Acting Endodomain of the Reovirus FAST Proteins

The reovirus fusion-associated small transmembrane (FAST) proteins are virus-encoded membrane fusion proteins that function as dedicated cell–cell fusogens. The topology of these small, single-pass membrane proteins orients the majority of the protein on the distal side of the membrane (i.e., inside the cell). We now show that ectopic expression of the endodomains of the p10, p14, and p15 FAST proteins enhances syncytiogenesis induced by the full-length FAST proteins, both homotypically and heterotypically. Results further indicate that the 68-residue cytoplasmic endodomain of the p14 FAST protein (1) is endogenously generated from full-length p14 protein expressed in virus-infected or transfected cells; (2) enhances syncytiogenesis subsequent to stable pore formation; (3) increases the syncytiogenic activity of heterologous fusion proteins, including the differentiation-dependent fusion of murine myoblasts; (4) exerts its enhancing activity from the cytosol, independent of direct interactions with either the fusogen or the membranes being fused; and (5) contains several regions with protein–protein interaction motifs that influence enhancing activity. We propose that the unique evolution of the FAST proteins as virus-encoded cellular fusogens has allowed them to generate a trans-acting, soluble endodomain peptide to harness a cellular pathway or process involved in the poorly understood process that facilitates the transition from microfusion pores to macrofusion and syncytiogenesis

Confidence and competence with mathematical procedures

Confidence assessment (CA), in which students state alongside each of their answers a confidence level expressing how certain they are, has been employed successfully within higher education. However, it has not been widely explored with school pupils. This study examined how school mathematics pupils (N = 345) in five different secondary schools in England responded to the use of a CA instrument designed to incentivise the eliciting of truthful confidence ratings in the topic of directed (positive and negative) numbers. Pupils readily understood the negative marking aspect of the CA process and their facility correlated with their mean confidence with r = .546, N = 336, p < .001, indicating that pupils were generally well calibrated. Pupils’ comments indicated that the vast majority were positive about the CA approach, despite its dramatic differences from more usual assessment practices in UK schools. Some pupils felt that CA promoted deeper thinking, increased their confidence and had a potential role to play in classroom formative assessment

The Caenorhabditis elegans GATA Factor ELT-1 Works through the Cell Proliferation Regulator BRO-1 and the Fusogen EFF-1 to Maintain the Seam Stem-Like Fate

Seam cells in Caenorhabditis elegans provide a paradigm for the stem cell mode of division, with the ability to both self-renew and produce daughters that differentiate. The transcription factor RNT-1 and its DNA binding partner BRO-1 (homologues of the mammalian cancer-associated stem cell regulators RUNX and CBFβ, respectively) are known rate-limiting regulators of seam cell proliferation. Here, we show, using a combination of comparative genomics and DNA binding assays, that bro-1 expression is directly regulated by the GATA factor ELT-1. elt-1(RNAi) animals display similar seam cell lineage defects to bro-1 mutants, but have an additional phenotype in which seam cells lose their stem cell-like properties and differentiate inappropriately by fusing with the hyp7 epidermal syncytium. This phenotype is dependent on the fusogen EFF-1, which we show is repressed by ELT-1 in seam cells. Overall, our data suggest that ELT-1 has dual roles in the stem-like seam cells, acting both to promote proliferation and prevent differentiation

The EFF-1A Cytoplasmic Domain Influences Hypodermal Cell Fusions in C. elegans But Is Not Dependent on 14-3-3 Proteins.

BACKGROUND: Regulatory and biophysical mechanisms of cell-cell fusion are largely unknown despite the fundamental requirement for fused cells in eukaryotic development. Only two cellular fusogens that are not of clear recent viral origin have been identified to date, both in nematodes. One of these, EFF-1, is necessary for most cell fusions in Caenorhabditis elegans. Unregulated EFF-1 expression causes lethality due to ectopic fusion between cells not developmentally programmed to fuse, highlighting the necessity of tight fusogen regulation for proper development. Identifying factors that regulate EFF-1 and its paralog AFF-1 could lead to discovery of molecular mechanisms that control cell fusion upstream of the action of a membrane fusogen. Bioinformatic analysis of the EFF-1A isoform\u27s predicted cytoplasmic domain (endodomain) previously revealed two motifs that have high probabilities of interacting with 14-3-3 proteins when phosphorylated. Mutation of predicted phosphorylation sites within these motifs caused measurable loss of eff-1 gene function in cell fusion in vivo. Moreover, a human 14-3-3 isoform bound to EFF-1::GFP in vitro. We hypothesized that the two 14-3-3 proteins in C. elegans, PAR-5 and FTT-2, may regulate either localization or fusion-inducing activity of EFF-1. METHODOLOGY/PRINCIPAL FINDINGS: Timing of fusion events was slightly but significantly delayed in animals unable to produce full-length EFF-1A. Yet, mutagenesis and live imaging showed that phosphoserines in putative 14-3-3 binding sites are not essential for EFF-1::GFP accumulation at the membrane contact between fusion partner cells. Moreover, although the EFF-1A endodomain was required for normal rates of eff-1-dependent epidermal cell fusions, reduced levels of FTT-2 and PAR-5 did not visibly affect the function of wild-type EFF-1 in the hypodermis. CONCLUSIONS/SIGNIFICANCE: Deletion of the EFF-1A endodomain noticeably affects the timing of hypodermal cell fusions in vivo. However, prohibiting phosphorylation of candidate 14-3-3-binding sites does not impact localization of the fusogen. Hypodermal membrane fusion activity persists when 14-3-3 expression levels are reduced

The phenomenology of the mathematics classroom

This paper describes the mathematics classroom from the perspective of social phenomenology. Here the classroom is seen as an environment of signs, comprising things and people, which impinge on the reality of the individual child. The paper introduces a framework through which mathematical work is seen as taking place in the imagined world through the filter of the world in immediate perception. This provides an approach to structuring evolving mathematical understanding. It is suggested that mathematical ideas are contained and shaped by the child's personal phenomenology, which evolves through time. Further, I argue these ideas are never encountered directly but rather are met through a circular hermeneutic process of reconciling expectation with experience. © 1996 Kluwer Academic Publishers

Delayed contralateral testicular metastases from renal cell carcinoma: a case report

No Abstract. African Journal of Urology Vol. 12(1) 2006: 29-3

Sensibilité développementale théorique et empirique des items de la Batterie d’Évaluation Cognitive et Socio-émotionnelle (BECS) pour l’évaluation du développement psychologique de très jeunes enfants au développement typique

International audienceThe Social and Cognitive Evaluation Battery (SCEB) is an instrument specifically created for the examination of pre-school and school-aged children with autism and intellectual disability and recommended by the French High Health Authority (HAS, 2010, 2011, 2012, 2018). The SCEB explores 16 functional abilities, in both cognitive and socio-emotional areas and allows the calculation of domains and areas developmental levels and heterogeneity indices for the global, cognitive and socio-emotional areas. Each of the 16 domains of the SCEB includes behavioral items hierarchized into 4 developmental levels corresponding to 4 age periods (level 1: 4–8 months; level 2: 8–12 months; level 3: 12–18 months; level 4: 18–24 months). The child's assessment provides a profile of the 16 levels of cognitive and socio-emotional development that can be interpreted within the framework of Piaget's (1977) and Fisher's (1980) theory. The study tests the developmental sensitivity of level scores and their adjustment to chronological ages and developmental ages assessed with the Brunet-Lézine Scale for 65 young typical developmental French children aged from 4 months to 24 months. The results show high sensitivity of scores and satisfactory adjustment to chronological and developmental age differences. Normative benchmarks are also given for indices of heterogeneity of development profiles, heterogeneity that decreases with age. Thus, the scores are interpretable in reference to theoretical models and can be used for the study of all developmental characteristics in infant and toddlers’ children with and without neurodevelopmental disorder.La Batterie d’Évaluation du développement Cognitif et Social (BECS) a été construite pour évaluer le développement de seize capacités chez des enfants ayant un trouble du spectre de l’autisme et un handicap intellectuel. Chacun des domaines de la BECS comprend des items hiérarchisés en 4 niveaux de développement correspondant à 4 périodes d’âges (1 : 4–8 mois ; 2 : 8–12 mois ; 3 : 12–18 mois ; 4 : 18–24 mois). Le profil des 16 niveaux de développement est interprétable dans le cadre de la théorie de Piaget (1977) et de celle de Fischer (1980). L’étude teste la sensibilité développementale des scores de niveaux et leur ajustement aux âges chronologiques pour 65 jeunes enfants au développement typique. Les résultats montrent une sensibilité élevée des scores et un ajustement satisfaisant aux différences d’âges chronologiques. Les scores sont interprétables en référence aux modèles théoriques et utilisables pour l’étude de toutes particularités développementales