Chapter 1 Synthesis and Function of Modified Nucleosides in tRNA

Author(s):  
Glenn R. Björk ◽  
Jürg Kohli
Author(s):  
Karen J. Esler ◽  
Anna L. Jacobsen ◽  
R. Brandon Pratt

Ecosystems are assemblages of organisms interacting with one another and their environment (Chapter 1). Key to the functioning of ecosystems is the flow of energy, carbon, mineral nutrients, and water in these systems. The numerous processes involved are chiefly driven by climate, soil, and fire (Chapter 2). In cases where the key drivers are the same in different areas, then ecosystems should converge in their structure and function, which has been a motivation for comparing across mediterranean-type climate (MTC) regions. Convergence of MTC regions has been evaluated, but such comparisons at the ecosystem level are challenging because ecosystems are complex and dynamic entities. Here we review carbon, nutrient, and water dynamics of mediterranean-type ecosystems in the context of ecosystem function. As nutrients in soils are low in some MTC regions, we review how this has led to unique adaptations to meet this challenge.


Author(s):  
Steven N. Dworkin

This book describes the linguistic structures that constitute Medieval or Old Spanish as preserved in texts written prior to the beginning of the sixteenth century. It emphasizes those structures that contrast with the modern standard language. Chapter 1 presents methodological issues raised by the study of a language preserved only in written sources. Chapter 2 examines questions involved in reconstructing the sound system of Old Spanish before discussing relevant phonetic and phonological details. The chapter ends with an overview of Old Spanish spelling practices. Chapter 3 presents in some detail the nominal, verbal, and pronominal morphology of the language, with attention to regional variants. Chapter 4 describes selected syntactic structures, with emphasis on the noun phrase, verb phrase, object pronoun placement, subject-verb-object word order, verb tense, aspect, and mood. Chapter 5 begins with an extensive list of Old Spanish nouns, adjectives, verbs, and function words that have not survived into the modern standard language. It then presents examples of coexisting variants (doublets) and changes of meaning, and finishes with an overview of the creation of neologisms in the medieval language through derivational morphology (prefixation, suffixation, compounding). The book concludes with an anthology composed of three extracts from Spanish prose texts, one each from the thirteenth, fourteenth, and fifteenth centuries. The extracts contain footnotes that highlight relevant morphological, syntactic, and lexical features, with cross references to the relevant sections in the body of the book.


2015 ◽  
Vol 197 (10) ◽  
pp. 1819-1827 ◽  
Author(s):  
Promisree Choudhury ◽  
Ann M. Flower

ABSTRACTThe bacterial BipA protein belongs to the EF-G family of translational GTPases and has been postulated to be either a regulatory translation factor or a ribosome assembly factor. To distinguish between these hypotheses, we analyzed the effect ofbipAdeletion on three phenotypes associated with ribosome assembly factors: cold sensitivity, ribosome subunit distribution, and rRNA processing. We demonstrated that a ΔbipAstrain exhibits a cold-sensitive phenotype that is similar to, and synergistic with, that of a strain with a known ribosome assembly factor,deaD. Additionally, thebipAdeletion strain displayed a perturbed ribosome subunit distribution when grown at low temperature, similar to that of adeaDmutant, and again, the double mutant showed additive effects. The primary ribosomal deficiency noted was a decreased level of the 50S subunit and the appearance of a presumed pre-50S particle. Finally, deletion ofbipAresulted in accumulation of pre23S rRNA, as did deletion ofdeaD. We further found that deletion ofrluC, which encodes a pseudouridine synthase that modifies the 23S rRNA at three sites, suppressed all three phenotypes of thebipAmutant, supporting and extending previous findings. Together, these results suggest that BipA is important for the correct and efficient assembly of the 50S subunit of the ribosome at low temperature but when unmodified by RluC, the ribosomes become BipA independent for assembly.IMPORTANCEThe ribosome is the complex ribonucleoprotein machine responsible for protein synthesis in all cells. Although much has been learned about the structure and function of the ribosome, we do not fully understand how it is assembled or the accessory proteins that increase efficiency of biogenesis and function. This study examined one such protein, BipA. Our results indicate that BipA either directly or indirectly enhances the formation of the 50S subunit of the ribosome, particularly at low temperature. In addition, ribosomes contain a large number of modified nucleosides, including pseudouridines. This work demonstrates that the function of BipA is tied to the modification status of the ribosome and may help us understand why these modifications have been retained.


Author(s):  
Vogenauer Stefan

This chapter contains three groups of ‘general provisions’ of the UNIDROIT Principles of International Commercial Contracts (PICC). The first group deals with fundamental principles of contract law, including freedom of contract, freedom from formal requirements, the bindingness of contract, good faith and fair dealing, and the so-called ‘prohibition of inconsistent behaviour’. The second group of provisions addresses the role and function of mandatory rules and the third group deals with the application of the PICC, focusing on general guidelines for the interpretation of the various articles of the instrument; specific key terms that are used throughout the following Chapters of the PICC such as ‘court’, ‘place of business’, ‘obligor’, ‘obligee’, and ‘writing’; the role of usages and practices established between the parties; and rules for certain scenarios that may arise in various contexts if the PICC apply.


Author(s):  
Chris O'Meara

Chapter 1 introduces the topic and explains the book’s context, purpose and importance. The chapter elaborates on how the International Court of Justice, scholars and states have approached necessity and proportionality and situates the book in relation to the current understanding of each requirement. The chapter proceeds to examine the provenance of necessity and proportionality (including consideration of the much-celebrated Caroline incident), as well as explaining the approach that this author takes to explore their contemporary meaning. Chapter 1 concludes by offering some initial observations on the nature and function of necessity and proportionality and the purposes of the right of self-defence that frame and underpin the subsequent analysis.


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