Investigation of the structure requirements for oligosaccharyl transferase function

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, September 2013.Cataloged from PDF version of thesis. "August 2013." Vita.Includes bibliographical references.N-linked glycosylation is a ubiquitous protein modification involved in a wide range of cellular functions and diseases (Varki, 1993). The oligosaccharyl transferase (OTase), the principle enzyme responsible for catalysis of N-linked glycosylation, facilitates the transfer of a preassembled oligosaccharide from a polyprenyl-lipid donor to the side-chain nitrogen of asparagine acceptors. In a majority of eukaryotes the OTase is a multimeric, membrane-bound complex, which has precluded detailed structural and mechanistic studies. The discovery of a homologous bacterial N-linked glycosylation system in 1999 provided new opportunities to study the fundamental biosynthetic and mechanistic components of the process. Specifically, the bacterial OTase, PglB, is monomeric and homologous to the catalytic subunit of the eukaryotic OTase. The following chapters describe studies designed to learn about the OTase transfer reaction using PglB as a model. Optimization of expression and purification of PglB is first described, as initial expression of PglB in E. coli showed poor yields and instability upon purification. Bioinformatic analysis was performed to define sequence regions of functional importance and to ascertain the extent of homology between PgIB and other OTases, which verified the value of Pg1B studies for understanding OTases generally. The bioinformatics analysis was based on topology predictions for PglB and various homologs. The general conservation in OTase membrane configuration was used to structurally guide and simplify sequence analyses for a large number of diverse OTases. The method revealed highly conserved motifs within the soluble loops appearing between transmembrane domains and biochemical analysis was carried out to establish the functional importance of these domains. These results were published concurrently with an independently determined X-ray crystal structure of PgIB, which validated and complemented the bioinformatic and biochemical results. Subsequently, a sensitive luminescent assay was designed and developed as a way to investigate the dynamics of substrate binding and conformational changes in the OTase reaction. Initial results demonstrate the informative value of the system. Measurements using this system will be continued by Imperiali lab members.by Marcie B. Jaffee.Ph.D

Protocol Risk factors for disruptive behaviours: protocol for a systematic review and meta-analysis of quasi-experimental evidence

Introduction: Disruptive behaviour disorders, including oppositional defiant disorder and conduct disorder, are a common set of diagnoses in childhood and adolescence, with global estimates of 5.7%, 3.6% and 2.1% for any disruptive disorder, oppositional defiant disorder and conduct disorder, respectively. There are high economic and social costs associated with disruptive behaviours and the prevalence of these disorders has increased in recent years. As such, disruptive behaviours represent an escalating major public health concern and it is important to understand what factors may influence the risk of these behaviours. Such research would inform interventions that aim to prevent the development of disruptive behaviours. The current review will identify the most stringent evidence of putative risk factors for disruptive behaviour from quasi-experimental studies, which enable stronger causal inference. Methods and analysis: The review will be carried out according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. An electronic search of references published between 1 January 1980 and 1 March 2020 will be conducted using Medline, Embase, PsycINFO and Web of Science. Initial abstract and title screening, full-text screening and data extraction will be completed independently by two reviewers using Evidence for Policy and Practice Information (EPPI)-Reviewer 4 software. Quasi-experimental studies in the English language examining the association between any putative risk factor and a clearly defined measure of disruptive behaviour (eg, a validated questionnaire measure) will be included. We will conduct meta-analyses if we can pool a minimum of three similar studies with the same or similar exposures and outcomes. Ethics and dissemination: The proposed review does not require ethical approval. The results will help to identify risk factors for which there is strong evidence of causal effects on disruptive behaviours and also highlight potential risk factors that require further research. The findings will be disseminated via publication in a peer-reviewed scientific journal and through presentations at international meetings and conferences

Simple guide to starting a research group

Conducting cutting-edge research and scholarship becomes more complicated with each passing year; forming a collaborative research group offers a way to navigate this increasing complexity. Yet many individuals whose work might benefit from the formation of a collaborative team may feel overwhelmed by the prospect of attempting to build and maintain a research group. We propose this simple guide for starting and maintaining such an enterprise

Parental predictors of children's executive functioning from ages 6 to 10.

According to prominent models of child development, parental factors may contribute to individual differences in children's executive functioning (EF). Here, we examine the relative importance of parents' socio-economic status, mental health, and parenting as predictors of EF development, drawing on a large (n = 1,070) community sample of Norwegian children who received biennial EF assessments from 6 to 10 years of age. We measure EF by means of the Behavior Rating Inventory of Executive Function. We assess parenting through observer ratings of parent-child interactions and parental mental health via the Beck Anxiety Inventory, Beck Depression Inventory, and Hopkins Symptom Checklist. When we adjust for all time-invariant unmeasured confounders, higher parental education predicts superior EF development, whereas harsh parenting forecasts poorer EF development. However, parenting does not mediate the effect of parental education. These results indicate that harsh parenting should be targeted in interventions aimed at improving EF. Statement of contribution What is already known on this subject? Parental factors seem to affect child development of executive functions (EF). Specifically, parental socio-economic status, mental health, and their parenting seem to influence the developmental course of child EF. What does this study add? To what degree the parental influence on EF development is likely to be driven by time-invariant factors, for example, genetics. The relative influence of positive and negative parenting on EF development

Consumer credit information systems: A critical review of the literature. Too little attention paid by lawyers?

This paper reviews the existing literature on consumer credit reporting, the most extensively used instrument to overcome information asymmetry and adverse selection problems in credit markets. Despite the copious literature in economics and some research in regulatory policy, the legal community has paid almost no attention to the legal framework of consumer credit information systems, especially within the context of the European Union. Studies on the topic, however, seem particularly relevant in view of the establishment of a single market for consumer credit. This article ultimately calls for further legal research to address consumer protection concerns and inform future legislation

March 1964

Turf and Lawn Grass Association Better turf through research and Educatio

Post-socialist housing systems in Europe:Housing welfare regimes by default?

This article develops a conceptual framework derived from welfare regime and concomitant literatures to interpret housing reform in post-socialist European countries. In it, settled power structures and collective ideologies are necessary prerequisites for the creation of distinctive housing welfare regimes with clear roles for the state, market and households. Although the defining feature of post-socialist housing has been mass-privatisation to create super-homeownership societies, the emphatic retreat of the state that this represents has not been replaced by the creation of the institutions or cultures required to create fully financialised housing markets. There is, instead, a form of state legacy welfare in the form of debt-free home-ownership, which creates a gap in housing welfare that has been partially filled by households in the form of intergenerational assistance (familialism) and self-build housing. Both of these mark continuities with the previous regime. The latter is especially common in south-east Europe where its frequent illegality represents a form of anti-state housing. The lack of settled ideologies and power structures suggests that these housing welfare regimes by default will persist as part of a process that resembles a path-dependent ‘transformation’ rather than ‘transition’

China and the changing economic geography of coffee value chains

For the past three centuries, the economic geography of the global coffee sector has been characterized by the supply of beans from tropical countries for consumption in North America and Europe, with various modes of value chain coordination enacted by lead firms to ensure reliable and affordable supply. This pattern is now fundamentally changing, with growth in coffee consumption in emerging markets, including China, exceeding that in established markets. But China is not only a growing consumer market, it is less well known that rapidly increasing agricultural production in Yunnan province of southwest China has also inserted the country as an important source region for coffee, and this has been pivotal in facilitating the emergence of Chinese lead firms in the sector. This article presents the emergence of China, and Chinese firms, at a critical juncture for the structure and governance of the global value chain for coffee. The processes through which this is occurring are outlined, and the implications for regional development prospects across Southeast Asia are discussed. We argue that the changing economic geography of coffee value chains, and their increasing driven-ness by Chinese actors, is starting to reshape the regional coffee industry in profoundly new ways

Tyrosine 23 Phosphorylation-Dependent Cell-Surface Localization of Annexin A2 Is Required for Invasion and Metastases of Pancreatic Cancer

The aggressiveness of pancreatic ductal adenocarcinoma (PDA) is characterized by its high metastatic potential and lack of effective therapies, which is the result of a lack of understanding of the mechanisms involved in promoting PDA metastases. We identified Annexin A2 (ANXA2), a member of the Annexin family of calcium-dependent phospholipid binding proteins, as a new molecule that promotes PDA invasion and metastases. We found ANXA2 to be a PDA-associated antigen recognized by post-treatment sera of patients who demonstrated prolonged survival following treatment with a PDA-specific vaccine. Cell surface ANXA2 increases with PDA development and progression. Knockdown of ANXA2 expression by RNA interference or blocking with anti-ANXA2 antibodies inhibits in vitro invasion of PDA cells. In addition, post-vaccination patient sera inhibits in vitro invasion of PDA cells, suggesting that therapeutic anti-ANXA2 antibodies are induced by the vaccine. Furthermore, cell-surface localization of ANXA2 is tyrosine 23 phosphorylation-dependent; and tyrosine 23 phosphorylation is required for PDA invasion. We demonstrated that tyrosine 23 phosphorylation resulting in surface expression of ANXA2 is required for TGFβ-induced, Rho-mediated epithelial-mesenchymal transition (EMT), linking the cellular function of ANXA2 which was previously shown to be associated with small GTPase-regulated cytoskeletal rearrangements, to the EMT process in PDA. Finally, using mouse PDA models, we showed that shRNA knock-down of ANXA2, a mutation at tyrosine 23, or anti-ANXA2 antibodies, inhibit PDA metastases and prolong mouse survival. Thus, ANXA2 is part of a novel molecular pathway underlying PDA metastases and a new target for development of PDA therapeutics

The Role of Individual Variables, Organizational Variables and Moral Intensity Dimensions in Libyan Management Accountants’ Ethical Decision Making

This study investigates the association of a broad set of variables with the ethical decision making of management accountants in Libya. Adopting a cross-sectional methodology, a questionnaire including four different ethical scenarios was used to gather data from 229 participants. For each scenario, ethical decision making was examined in terms of the recognition, judgment and intention stages of Rest’s model. A significant relationship was found between ethical recognition and ethical judgment and also between ethical judgment and ethical intention, but ethical recognition did not significantly predict ethical intention—thus providing support for Rest’s model. Organizational variables, age and educational level yielded few significant results. The lack of significance for codes of ethics might reflect their relative lack of development in Libya, in which case Libyan companies should pay attention to their content and how they are supported, especially in the light of the under-development of the accounting profession in Libya. Few significant results were also found for gender, but where they were found, males showed more ethical characteristics than females. This unusual result reinforces the dangers of gender stereotyping in business. Personal moral philosophy and moral intensity dimensions were generally found to be significant predictors of the three stages of ethical decision making studied. One implication of this is to give more attention to ethics in accounting education, making the connections between accounting practice and (in Libya) Islam. Overall, this study not only adds to the available empirical evidence on factors affecting ethical decision making, notably examining three stages of Rest’s model, but also offers rare insights into the ethical views of practising management accountants and provides a benchmark for future studies of ethical decision making in Muslim majority countries and other parts of the developing world