tRNA nucleotidyltransferase adds the invariant CCA‐terminus to the tRNA 3′‐end, a central step in tRNA maturation. This CCA‐adding enzyme is a specialized RNA polymerase that synthesizes the CCA sequence at high fidelity in all kingdoms of life. Recently, an additional function of this enzyme was identified, where it generates a specific degradation tag on structurally unstable tRNAs. This tag consists of an additional repeat of the CCA triplet, leading to a 3′‐terminal CCACCA sequence. In order to explain (...) how the enzyme catalyzes this extended polymerization reaction, Kuhn et al. solved a series of co‐crystal structures of the CCA‐adding enzyme from Archaeoglobus fulgidus in complex with different tRNA substrates. They show that the enzyme forces a bound unstable tRNA to refold the acceptor stem for a second round of CCA‐addition, while stable transcripts are robust enough to resist this isomerization. In this review, we discuss how the CCA‐adding enzyme uses a simple yet very elegant way to scrutinize its substrates for sufficient structural stability and, consequently, functionality. (shrink)

Telomerase is a cellular reverse transcriptase responsible for telomere maintenance in most organisms. It does so by adding telomere repeats onto pre‐existing ends using an integral RNA component as template. Compared to “prototypical” reverse transcriptases, telomerase is unique in being able to repetitively copy a short templating RNA segment, thus adding multiple copies of the repeat to the DNA substrate following a single binding event. This uniquely processive property hints at the intricate conformational alterations that the enzyme (...) must choreograph during its reaction cycles. Recent studies have identified distinct structural elements within both the RNA and protein components of telomerase that modulate enzyme processivity. Pharmacological and genetic analysis suggest that telomerase processivity is a significant determinant of telomere length. Because telomere maintenance and the lack thereof have been linked to tumor progression and aging, further investigation of telomerase processivity may lead to novel medical intervention strategies. BioEssays 26:955–962, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

The present account spans the history of arginine regulation from its discovery in 1955 until the present. In 1957 I demonstrated that not only added arginine but also internally produced arginine represses enzyme formation and that the potential for enzyme synthesis is in excess of what is required for growth. In 1959 I located the regulatory gene argR encoding the arginine repressor. An unusual feature of this research was the finding that in E. coli B, in contrast to (...) E. coli K12, arginine synthesis is permanently repressed, independent of arginine. This was due to a single amino acid difference between the two repressors. Recent studies showed that, in natural populations of E. coli, K12‐type regulation is much more frequent than B‐type regulation, and that E. coli B evolved from a strain with K12‐type regulation. In competition experiments, E. coli K12 was found to be favored in the presence of arginine and E. coli B in its absence, showing that contrary to expectations permanently turned off regulation is favored over negative regulation in some environments. BioEssays 29:484–488, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

Hindu religious philosophy of femininity.

Anonymous commentary on Jaimini's Mīmāṃsāsūtra, aphoristic work setting forth the tenets of the Mīmāṃsā school in Hindu philosophy.

Name der Zeitschrift: Der Islam Jahrgang: 94 Heft: 1 Seiten: 66-93.

Until now, adult crying has received relatively little interest from investigators, whereas in the popular media there are many strong claims about crying of which the scientific basis is not clear. In this review, we provide an overview of the current state of the scientific literature with respect to crying. We identify gaps in knowledge and propose questions for future research. The following topics receive special attention: Ontogenetic development, antecedents, individual and gender differences, and the intra- and interindividual effects of (...) crying. We conclude that the study of crying may help us obtain better insight into human nature, that is, not only our emotional, but also social, and moral functioning. (shrink)

Traditional Turkish love is identified with suffering. This study investigates how suffering in love is metaphorically conceptualized in Turkish via natural phenomena and disasters. Based on figura...

Bu çalışmada “tabiat” kavramının sözlük ve terim anlamı analiz edilmiş ve ona ilişkin bazı Meşşâî İslam filozoflarının görüşlerine yer verilmiştir. “Tabiat” sözcüğünü karşılamak üzere Türkçede kullanılan “tabiat” ve “doğa” sözcükleri arasında bir karşılaştırma yapılmıştır. “Tabiat”ın Meşşâî İslam filozofları tarafından isim olarak kullanıldığı varlık alanı hakkında bilgi verilmiş ve İbn Sina ile İbn Rüşd arasında cereyan eden tabiatın ispatının gerekip gerekmeyeceği tartışmasına değinilmiştir. Cisimlerde görülen hareket ve sükunun kaynağı olması bakımından “tabiat”ın nelere delalet ettiği hususunda İbn Sina’nın görüşleri Aristo ile mukayeseli (...) olarak sunulmuştur. Daha sonra bir terim olarak “tabiat”ın filozoflar tarafından yapılan tanımı ortaya konulmuştur. İslam felsefesinde önemli bir yere sahip olan “tabiat” kavramına Meşşâî İslam filozoflarının yükledikleri anlam ve onu kullanma biçimleri, Aristo’dan farklıdır. Özellikle her türlü oluş ve hareketin kaynağını açıklamak amacıyla kullandıkları “tabiat” kavramı etimolojik açıdan tüm nedenleri Allah’a ulaştırmaya imkan sağlamaktadır. Ayrıca kavramın, “tabiat – tabiat ötesi” ayrımına dayanak teşkil ettiği de bilinmektedir. Makalenin amacı, “tabiat” kavramının günümüzde yeni teorilerle ilişkili olarak kullanılma imkanlarını belirginleştirmektir. (shrink)

Collection of the papers on language and globalization.

Cet article tente de montrer que la révolution qui s’est produite en Égypte était porteuse d’un projet politique libéral-démocrate. Les groupes révolutionnaires et les opposants au régime de Moubarak ont réussi à mobiliser des couches sociales substantielles en 2011 en demandant le respect des droits humains de base et la représentation de la volonté du peuple. La forte présence d’ouvriers mécontents, de classes moyennes appauvries et de populations urbaines défavorisées dans le mouvement de protestation n’a jamais débouché sur un projet (...) politique visant un changement économique et social. Leurs revendications sont restées figées dans une économie morale nassériste où les revendications économiques et sociales sont en grande partie apolitiques et totalement dissociées de la démocratisation des relations entre la société et l’État. L’absence de projet de changement socio-politique a privé le processus révolutionnaire d’une large et solide coalition sociale. (shrink)

“Maqamat as-Sufiyya” is a small theoretical works of Shihab ad-Din as-Suhrawardi (ab. 1154-1191), the founder of the Philosophy of Illumination. It contains practical instructions and theoretical reflections and proofs. As-Suhrawardi especially notes terminology used by philosophers and terminology used by sufis in “Maqamat as-Sufiyya”.

Elementary Buddhist logic and dialectical studies.

An examination of British and French weights exchanged between the Royal Society and the Académie royale des sciences in the 1730s has led to a re‐assessment of the Elizabethan troy standards from the Exchequer and the suggestion that the mass of the troy pound has been revised upwards. In turn this is used to support the idea of an evolutionary relationship between the early bullion ounces of England, France, and the Low Countries.

Summary The contribution of the Antwerp mathematician and instrument maker Michiel Coignet to the development of the sector is investigated. It will be shown that he invented a rule, the reigle platte, which he later used in conjunction with Mordente's reduction compass, thus in effect performing the same operations as with a sector. Later Coignet transferred the scales to the legs of the compass thereby making his first sector, which bore a resemblance to the reduction compass.