Unisite ATP hydrolysis by soluble Rhodospirillum rubrum F1–ATPase is accelerated by Ca2+

AbstractAt saturating concentrations of ATP, soluble F1 from the Rhodospirillum rubrum (RF1) exhibits a higher rate of hydrolysis with Ca2+ than with Mg2+. The mechanisms involved in the expression of a higher catalytic activity with Ca2+ were explored by measuring the ATPase activity of RF1 at substiochiometric concentrations of ATP (unisite conditions). At a ratio of 0.25 [γ-32P]ATP per RF1, the enzyme exhibited a 50 times higher hydrolytic rate with Ca2+ than with Mg2+. The rate of [γ-32P]ATP binding to RF1 was in the same range with the two divalent metal ions. Centrifugation–filtration of RF1 exposed to substoichiometric [γ-32P]ATP concentrations and Mg2+ through Sephadex columns yielded an enzyme that contained [γ-32P]ATP and [32P]phosphate in a stoichiometry that was close to one. In the presence of Ca2+, the eluted enzyme did not contain [γ-32P]ATP nor [32P]phosphate. This indicated that the rate of product release was faster with Ca2+ than with Mg2+. It was also observed that the ratio of multisite to unisite hydrolysis rates was of similar magnitude with both divalent cations. This suggests that they do not affect differently the cooperative mechanisms that may exist between catalytic sites. In consequence, the higher ATPase activity of RF1 in presence of Ca2+ strongly suggests that the retention time of products is decreased in the presence of this cation

A New Yeast Poly(A) Polymerase Complex Involved in RNA Quality Control

Eukaryotic cells contain several unconventional poly(A) polymerases in addition to the canonical enzymes responsible for the synthesis of poly(A) tails of nuclear messenger RNA precursors. The yeast protein Trf4p has been implicated in a quality control pathway that leads to the polyadenylation and subsequent exosome-mediated degradation of hypomethylated initiator tRNA(Met) (tRNA(i) (Met)). Here we show that Trf4p is the catalytic subunit of a new poly(A) polymerase complex that contains Air1p or Air2p as potential RNA-binding subunits, as well as the putative RNA helicase Mtr4p. Comparison of native tRNA(i) (Met) with its in vitro transcribed unmodified counterpart revealed that the unmodified RNA was preferentially polyadenylated by affinity-purified Trf4 complex from yeast, as well as by complexes reconstituted from recombinant components. These results and additional experiments with other tRNA substrates suggested that the Trf4 complex can discriminate between native tRNAs and molecules that are incorrectly folded. Moreover, the polyadenylation activity of the Trf4 complex stimulated the degradation of unmodified tRNA(i) (Met) by nuclear exosome fractions in vitro. Degradation was most efficient when coupled to the polyadenylation activity of the Trf4 complex, indicating that the poly(A) tails serve as signals for the recruitment of the exosome. This polyadenylation-mediated RNA surveillance resembles the role of polyadenylation in bacterial RNA turnover

Discourse and religion in educational practice

Despite the existence of long-held binaries between secular and sacred, private and public spaces, school and religious literacies in many contemporary societies, the significance of religion and its relationship to education and society more broadly has become increasingly topical. Yet, it is only recently that the investigation of the nexus of discourse and religion in educational practice has started to receive some scholarly attention. In this chapter, religion is understood as a cultural practice, historically situated and embedded in specific local and global contexts. This view of religion stresses the social alongside the subjective or experiential dimensions. It explores how through active participation and apprenticeship in culturally appropriate practices and behaviors often mediated intergenerationally and the mobilisation of linguistic and other semiotic resources but also affective, social and material resources, membership in religious communities is constructed and affirmed. The chapter reviews research strands that have explored different aspects of discourse and religion in educational practice as a growing interdisciplinary field. Research strands have examined the place and purpose of religion in general and evangelical Christianity in particular in English Language Teaching (ELT) programmes and the interplay of religion and teaching and learning in a wide range of religious and increasingly secular educational contexts. They provide useful insights for scholars of discourse studies to issues of identity, socialisation, pedagogy and language policy

Lagergren (David) Mission and State in the Congo

Dreyfus François-Georges. Lagergren (David) Mission and State in the Congo. In: Archives de sociologie des religions, n°33, 1972. p. 263

Berkovitz (Morris I.) Johnson (J.E.) Social Scientific Studies of Religion: a Bibliography

Dreyfus François-Georges. Berkovitz (Morris I.) Johnson (J.E.) Social Scientific Studies of Religion: a Bibliography. In: Archives de sociologie des religions, n°30, 1970. pp. 174-175

Warren-Candler Seoville, The persecution of Huguenots and French economic Development (1680-1720). Berkeley, Los Angeles, University of California Press, 1960

Dreyfus François-Georges. Warren-Candler Seoville, The persecution of Huguenots and French economic Development (1680-1720). Berkeley, Los Angeles, University of California Press, 1960. In: Revue d'histoire et de philosophie religieuses, 41e année n°4,1961. pp. 436-438

Robert Collinet, La Réformation en Belgique au XVIe siècle, Tome 1 de l'Histoire du protestantisme en Belgique et au Congo belge, 1958 Samuel Mours, Le Protestantisme en France au XVIe siècle, 1959

Dreyfus François-Georges. Robert Collinet, La Réformation en Belgique au XVIe siècle, Tome 1 de l'Histoire du protestantisme en Belgique et au Congo belge, 1958 Samuel Mours, Le Protestantisme en France au XVIe siècle, 1959. In: Revue d'histoire et de philosophie religieuses, 39e année n°4,1959. pp. 401-402