Transcription factor interactions at the promoter of the Arabidopsis circadian clock gene LHY

The circadian clock is the endogenous mechanism by which a wide variety of biological processes are regulated in anticipation of daily changes in the external environment. In Arabidopsis thaliana, the clock comprises a number of complex gene and protein interactions, involving multiple regulatory feedback loops. The clock gene LHY has a central role in these loops, activating and repressing morning- and evening- expressed genes respectively. These clock genes in turn sequentially repress the expression of LHY throughout the day and night, restricting it to a sharp transcriptional peak at dawn. However, the molecular mechanisms of these regulatory interactions with the LHY promoter were not known. Therefore, this project first aimed to determine which promoter motifs are responsible for mediating regulation of LHY circadian expression. This was achieved through luciferase assays with mutated pLHY:LUC reporter constructs, which identified the CT-rich region as responsible for rhythmic expression of LHY, and the G-box as mediating regulation by the clock protein TOC1. Since few regulators were known to target the LHY promoter, this project also aimed to identify transcription factors binding the promoter using a Yeast One-Hybrid assay. Transcription factors with roles in a wide variety of biological pathways were identified from this screen, with abiotic stress and plant defence pathways particularly well-represented. In addition, a number of antagonistic and synergistic regulatory interactions were established as occurring between stress factors and clock proteins at specific promoter motifs. We can therefore conclude that LHY is regulated by a complex network of transcription factor interactions, enabling the rapid integration of environmental stress signals into the clock

A study of Arthurian poetry in the English Renaissance, from Spenser to Dryden.

This thesis traces the development of Arthurian literature through the sixteenth and seventeenth centuries. A comparison of the Medieval flawed romance king and of the epic warrior of the English histories with Spenser's treatment of Arthur in The Faerie Queene reveals the extent of Spenser's originality. Spenser irreversibly altered the course of English Arthurian literature by rejecting Arthur's traditional human failings and by creating a figure of moral and political idealism. These forms of perfection --- intimately connected in the poem to Protestantism, Neoplatonism, nationalism and monarchism --- initiated two divergent, but not mutually exclusive, strands of Arthurian literature in the seventeenth century. Spenser's Arthurian idealism manifests itself in the courtly masques, and especially in Ben Jonson's Prince Henry's Barriers (1610) and Prince Oberon (1611), Thomas Carew's Coelum Britannicum (1633) and William Davenant's Britannia Triumphans (1637). The masques affirm the link between Spenserian Arthurianism and moral perfection, but the Spenserian poets soon raised doubts regarding this pure 'idealism'. This group of poets, particularly Drayton, simultaneously imitate and alter Spenser's use of Arthurian material. In Poly-Olbion (1633)Drayton adapts Spenser's concept of Arthur in order to contrast Arthurianism with Christianity and historicity. Spenser's Arthurian concepts of heroism, nationalism and monarchy initiated in The Faerie Queene are prominent in the political panegyrics of the Stuart period, and are fully explored by Ralph Knevett in A Supplement of the Faery Queene (1635). While Knevett proposes an allegorical representation of political idealism in his Arthurian material, he simultaneously evinces an astute awareness of the increasing contemporary demands for greater veracity and realism in fiction.Towards the end of the seventeenth century Arthurian idealism was losing its momentum. Its final demise can be traced in the works of Milton and Dryden. Milton was initially attracted by Spenser's treatment of Arthur, but he followed the Spenserians in utilizing the moral Arthurian material primarily to foreground the higher truths of Christianity in Paradise Lost (1667) and Paradise Regained (1671). By the time Dryden completed King Arthur (1691), the Arthurian tradition could no longer sustain its traditional imaginative appeal.<p

Effect of composition and austenite deformation on the transformation characteristics of low-carbon and ultralow-carbon microalloyed steels

Deformation dilatometry has been used to simulate controlled hot rolling followed by controlled cooling of a group of low- and ultralow-carbon microalloyed steels containing additions of boron and/or molybdenum to enhance hardenability. Each alloy was subjected to simulated recrystallization and nonrecrystallization rolling schedules, followed by controlled cooling at rates from 0.1 &deg;C/s to about 100 &deg;C/s, and the corresponding continuous-cooling-transformation (CCT) diagrams were constructed. The resultant microstructures ranged from polygonal ferrite (PF) for combinations of slow cooling rates and low alloying element contents, through to bainitic ferrite accompanied by martensite for fast cooling rates and high concentrations of alloying elements. Combined additions of boron and molybdenum were found to be most effective in increasing steel hardenability, while boron was significantly more effective than molybdenum as a single addition, especially at the ultralow carbon content. Severe plastic deformation of the parent austenite (&gt;0.45) markedly enhanced PF formation in those steels in which this microstructural constituent was formed, indicating a significant effective decrease in their hardenability. In contrast, in those steels in which only nonequilibrium ferrite microstructures were formed, the decreases in hardenability were relatively small, reflecting the lack of sensitivity to strain in the austenite of those microstructural constituents forming in the absence of PF.<br /