Structure analysis of biologically important prokaryotic glycopolymers

Of the many post-translational modifications organisms can undertake, glycosylation is the most prevalent and the most diverse. The research in this thesis focuses on the structural characterisation of glycosylation in two classes of glycopolymer (lipopolysaccharide (LPS) and glycoprotein) in two domains of life (bacteria and archaea). The common theme linking these subprojects is the development and application of high sensitivity analytical techniques, primarily mass spectrometry (MS), for studying prokaryotic glycosylation. Many prokaryotes produce glycan arrangements with extraordinary variety in composition and structure. A further challenge is posed by additional functionalities such as lipids whose characterisation is not always straightforward. Glycosylation in prokaryotes has a variety of different biological functions, including their important roles in the mediation of interactions between pathogens and hosts. Thus enhanced knowledge of bacterial glycosylation may be of therapeutic value, whilst a better understanding of archaeal protein glycosylation will provide further targets for industrial applications, as well as insight into this post- translational modification across evolution and protein processing under extreme conditions. The first sub-project focused on the S-layer glycoprotein of the halophilic archeaon Haloferax volcanii, which has been reported to be modified by both glycans and lipids. Glycoproteomic and associated MS technologies were employed to characterise the N- and O-linked glycosylation and to explore putative lipid modifications. Approximately 90% of the S-layer was mapped and N-glycans were identified at all the mapped consensus sites, decorated with a pentasaccharide consisting of two hexoses, two hexuronic acids and a methylated hexuronic acid. The O-glycans are homogeneously identified as a disaccharide consisting of galactose and glucose. Unexpectedly it was found that membrane-derived lipids were present in the S- layer samples despite extensive purification, calling into question the predicted presence of covalently linked lipid. The H. volcanii N-glycosylation is mediated by the products of the agl gene cluster and the functional characterisation of members of the agl gene cluster was investigated by MS analysis of agl-mutant strains of the S-layer. Burkholderia pseudomallei is the causative agent of melioidosis, a serious and often fatal disease in humans which is endemic in South-East Asia and other equatorial regions. Its LPS is vital for serum resistance and the O-antigen repeat structures are of interest as vaccine targets. B. pseudomallei is reported to produce several polysaccharides, amongst which the already characterised ‘typical’ O-antigen of K96243 represents 97% of the strains. The serologically distinct ‘atypical’ strain 576 produces a different LPS, whose characterisation is the subject of this research project. MS strategies coupled with various hydrolytic and chemical derivatisation methodologies were employed to define the composition and potential sequences of the O-antigen repeat unit. These MS strategies were complemented by a novel NMR technique involving embedding of the LPS into micelles. Taken together the MS and NMR data have revealed a highly unusual O-antigen structure for atypical LPS which is remarkably different from the typical O-antigen. The development of structural analysis tools in MS and NMR applicable to the illustrated types of glycosylation in these prokaryotes will give a more consistent approach to sugar characterisation and their modifications thus providing more informative results for pathogenicity and immunological studies as well as pathway comparisons.Open Acces

Cohomology of finite monogenic self-distributive structures

A shelf is a set with a binary operation~\op satisfying a \op (b \op c) = (a \op b) \op (a \op c). Racks are shelves with invertible translations b \mapsto a \op b; many of their aspects, including cohomological, are better understood than those of general shelves. Finite monogenic shelves (FMS), of which Laver tables and cyclic racks are the most famous examples, form a remarkably rich family of structures and play an important role in set theory. We compute the cohomology of FMS with arbitrary coefficients. On the way we develop general tools for studying the cohomology of shelves. Moreover, inside any finite shelf we identify a sub-rack which inherits its major characteristics, including the cohomology. For FMS, these sub-racks are all cyclic

Law\u27s Constitution: A Relational Critique

It is a simple fact: we begin from others. Without others we, quite literally, could not live, feel, be born. Every mother, every mother\u27s partner, every father, every child, knows this. But law sees these relations as something lesser, as foreign. Mention the word relationship to the average lawyer and she will likely assume that you are talking about sex, dating, or perhaps marriage. She may even wonder what relationship has to do with the law at all. In this paper, the author wonders whether it is possible to flip that equation, to think of the relational as central, rather than peripheral, to law\u27s most ambitious public projects. Her hypothesis is two-fold: first, that the relational question is known by, and important to, feminism; and, second, that the relational is important beyond feminism, indeed that it is important to our ideas of constitution and law itself. If this is right, then focusing on relationships is far from the marginal project that it is often assumed to be. Indeed, it may allow feminism to predict new ways of seeing law. The author offers examples from her own legal experience--in criminal law and constitutional law--that shows what she calls (for lack of a better term) the relational critique. What she mean by this is two things: (1) that many of the concepts that we see in law, that seem mundane, natural or given, stand as proxies for normative relations; (2) that by disaggregating the natural object--by seeing relations in naturalized descriptions--we can see the law creating/ generating/constituting. Put another way, this paper is about thinking relationally—the author wonders whether it is possible or wise to substitute the relational question for the sameness question or the difference question--not only in cases of concern to feminists but cases elsewhere in the law

Nothing but the Truth, take two: fighting for the reader in the Tlatelolco 1968 discourse

The hypothesis put forward in this project is that there are two mechanisms of creating a collective memory of the event: one is hegemonic (dominated by state discourses and, potentially, academic studies of the shooting), and the other is posthegemonic (dominated by literary and popular discourses). We also posit that neither mechanism produces or even aims to produce an accurate representation of the event; instead, the two systems control cognitive and affective domains in collective conscience. The present paper will compare the way the two mechanisms are used in the contemporary analyses of the Tlatelolco massacre. The two works in question are Roberto Blanco Moheno, Tlatelolco: historia de una infamia (1969), and Guillermo Balám, Tlatelolco: Reflexiones de un testigo (1969). I aim to determine whether the two authors, apparently representing the opposing camps in the Tlatelolco discourse, approach the representation of the massacre from two divergent perspectives or whether their texts are characterised by the unity of the mechanisms involved in creating a memory of the event in the collective conscience

Utilizing Multi-level Classification Techniques to Predict Adverse Drug Effects and Reactions

Multi-class classification models are used to predict categorical response variables with more than two possible outcomes. A collection of multi-class classification techniques such as Multinomial Logistic Regression, Na\ {i}ve Bayes, and Support Vector Machine is used in predicting patients’ drug reactions and adverse drug effects based on patients’ demographic and drug administration. The newly released 2018 data on drug reactions and adverse drug effects from U.S. Food and Drug Administration are tested with the models. The applicability of model evaluation measures such as sensitivity, specificity and prediction accuracy in multi-class settings, are also discussed