Investigation of the function of branching enzymes I, IIa, and IIb in the determination of amylopectin structure and regulation of starch biosynthesis

Starch is one of the most abundant carbohydrates on earth serving vital roles as the primary energy reserve of plants, a significant source of calories in the human diet, and a renewable resource for other industrial applications. The multiplicity of starch biosynthetic enzymes is evolutionarily conserved in plants suggesting their functions are essential in starch biosynthesis. The overall goal of this research is to determine the specific molecular functions of the multiple starch branching enzyme (BE) isoforms in maize.;This dissertation first addresses what, if any, are the differences in enzymatic properties of BEIIa and BEIIb. Two polyclonal antisera were produced, alphaBEI and alphaBEIIab which specifically identify BEI and both BEII isoforms, respectively. Chromatographic purification techniques separated native BEIIa or BEIIb from the other two branching enzymes. The capacities to modify the structure of amylose were compared between native BEIIa and BEIIb and recombinant BEIIa (rIIa). The evolutionary conservation of BEIIa and BEIIb is not accounted for by their enzymatic differences. Differences in the glucan chain length distribution created by native BEIIa and rIIa suggest that in vivo there are factors affecting the activity of BEs.;This dissertation next addresses are branching enzymes involved in multi-subunit complexes (MSCs)? This research provides direct evidence BEIIa and SSI interact with each other in MSC and that SSIII may be a component of the MSCs. Indirect evidence from GPC analysis of BEIIb and multiple electrophoretic mobility forms of BEI suggests that they may be involved in MSCs. Pleiotropic effects in branching enzyme mutants on starch synthase (SS) activity revealed at least three SS band activities are affected when BEIIa was mutated. Further research is needed to investigate the functional significance of the complexes involving BEIIa, SSI and possibly SSIII.;This dissertation addresses what branching enzyme isoforms exist in leaves as compared to endosperm. The same BEI polypeptide present in maize endosperm was found to be present in maize leaves. Leaf BEI was found to be similar to endosperm BEI in predicted molecular weight, approximately 80 kDa, in molecule size, a monomeric protein, and also possesses multiple electrophoretic mobility forms

Using the Man9(GlcNAc)2 – DC-SIGN pairing to probe specificity in photochemical immobilization

We demonstrate the expected preference of an immobilised oligosaccharide Man(9)(GlcNAc)(2) upon a 96-well photochemical array, for its known receptor, the cell-surface lectin Dendritic Cell-Specific ICAM3 Grabbing Nonintegrin (DC-SIGN) when compared to immobilised competing monosaccharides

White Light Flare Continuum Observations with ULTRACAM

We present sub-second, continuous-coverage photometry of three flares on the dM3.5e star, EQ Peg A, using custom continuum filters with WHT/ULTRACAM. These data provide a new view of flare continuum emission, with each flare exhibiting a very distinct light curve morphology. The spectral shape of flare emission for the two large-amplitude flares is compared with synthetic ULTRACAM measurements taken from the spectra during the large 'megaflare' event on a similar type flare star. The white light shape during the impulsive phase of the EQ Peg flares is consistent with the range of colors derived from the megaflare continuum, which is known to contain a Hydrogen recombination component and compact, blackbody-like components. Tentative evidence in the ULTRACAM photometry is found for an anti-correlation between the emission of these components.Comment: 8 pages, 3 figures. Proceedings of the 16th Workshop on Cool Stars, Stellar Systems, and the Sun (PASP conference series, in press

Examining the Focus of SoTL Literature—Teaching and Learning?

Although the Scholarship of Teaching and Learning (SoTL) claims to focus on student learning, some have argued that SoTL studies often adopt a narrow view of learning and focus more on teaching than on learning. In this paper, we explore whether teaching is the primary focus of recent articles published from 2013-2017 in three international, self-identified SoTL journals: Teaching and Learning Inquiry: The ISSOTL Journal (TLI), The International Journal for the Scholarship of Teaching and Learning (ijSOTL), and The Journal of the Scholarship of Teaching and Learning (JoSoTL). Based on our analysis of the 299 empirical articles, we argue that they portray SoTL as a field focused primarily on teacher activity rather than student learning, despite efforts to broaden its scope

‘My favourite things to do’ and ‘my favourite people’: Exploring salient aspects of children’s self-concept

This study explores the potential of the ‘draw-and-write’ method for inviting children to communicate salient aspects of their self-concept. Irish primary school children aged 10–13 years drew and wrote about their favourite people and things to do (social and active self). Children drew and described many salient activities (39 in total) and people – including pets. Results suggest that widely used, adult-constructed self-esteem scales for children, while multidimensional, are limited, and that ‘draw-and-write’ is an effective multimodal method with which children can express their social and active self-concepts

How Valid Are Measures of Children’s Self-Concept/ Self-Esteem? Factors and Content Validity in Three Widely Used Scales

Children’s self-esteem/self-concept, a core psychological construct, has been measured in an overwhelming number of studies, and the widespread use of such measures should indicate they have well-established content validity, internal consistency and factor structures. This study, sampling a demographically representative cohort in late childhood/early adolescence in Dublin, Ireland (total n = 651), examined three major self-esteem/self-concept scales designed for late childhood/early adolescence: Piers-Harris Self-Concept Scale for Children 2 (Piers et al. 2002), Self-Description Questionnaire I (Marsh 1992) and Self-Perception Profile for Children (Harter 1985). It also examined findings in light of the salient self factors identified by participants in a linked mixed-methods study. The factor structure of Piers-Harris Self-Concept Scale was not replicated. The Self-Description Questionnaire I and Self-Perception Profile for Children were replicated only in part although in similar ways. In all three scales, a global/ appearance self evaluation factor accounted for the largest variance in factor analyses. Sport/athletic ability, school ability, school enjoyment, maths and reading ability/enjoyment, behaviour, peer popularity, and parent factors were also identified but did not always reflect existing scale structures. Notably, the factors extracted, or items present in these scales, often did not reflect young people’s priorities, such as friendship over popularity, the importance of family and extended family members, and the significance of incremental personal mastery in activities rather than assessing oneself as comparatively good at preferred activities. The findings raise questions about how self-esteem/self-concept scales are used and interpreted in research with children and young people

Journeys through the Golgi—taking stock in a new era

The Golgi apparatus is essential for protein sorting and transport. Many researchers have long been fascinated with the form and function of this organelle. Yet, despite decades of scrutiny, the mechanisms by which proteins are transported across the Golgi remain controversial. At a recent meeting, many prominent Golgi researchers assembled to critically evaluate the core issues in the field. This report presents the outcome of their discussions and highlights the key open questions that will help guide the field into a new era

Who I Am: The Meaning of Early Adolescents’ Most Valued Activities and Relationships, and Implications for Self-Concept Research

Self-concept research in early adolescence typically measures young people’s self-perceptions of competence in specific, adult-defined domains. However, studies have rarely explored young people’s own views of valued self-concept factors and their meanings. For two major self domains, the active and the social self, this mixed-methods study identified factors valued most by 526 young people from socioeconomically diverse backgrounds in Ireland (10-12 years), and explored the meanings associated with these in a stratified subsample (n = 99). Findings indicate that self-concept scales for early adolescence omit active and social self factors and meanings valued by young people, raising questions about content validity of scales in these domains. Findings also suggest scales may under-represent girls’ active and social selves; focus too much on some school-based competencies; and, in omitting intrinsically salient self domains and meanings, may focus more on contingent (extrinsic) rather than true (intrinsic) self-esteem