Preferential binding and structural distortion by Fe2+ at RGGG-containing DNA sequences correlates with enhanced oxidative cleavage at such sequences.

Certain DNA sequences are known to be unusually sensitive to nicking via the Fe2+-mediated Fenton reaction. Most notable are a purine nucleotide followed by three or more G residues, RGGG, and purine nucleotides flanking a TG combination, RTGR. Our laboratory previously demonstrated that nicking in the RGGG sequences occurs preferentially 5' to a G residue with the nicking probability decreasing from the 5' to 3'end of these sequences. Using 1H NMR to characterize Fe2+ binding within the duplex CGAGTTAGGGTAGC/GCTACCCTAACTCG and 7-deazaguanine-containing (Z) variants of it, we show that Fe2+ binds preferentially at the GGG sequence, most strongly towards its 5' end. Substitutions of individual guanines with Z indicate that the high affinity Fe2+ binding at AGGG involves two adjacent guanine N7 moieties. Binding is accompanied by large changes in specific imino, aromatic and methyl proton chemical shifts, indicating that a locally distorted structure forms at the binding site that affects the conformation of the two base pairs 3' to the GGG sequence. The binding of Fe2+ to RGGG contrasts with that previously observed for the RTGR sequence, which binds Fe2+ with negligible structural rearrangements

The elephant-wallahs\u27 microcosm

O canyon do Guartelá situa-se no curso médio do Rio Tibagi desenvolvido no arenito Fumas. Sua evolução deve-se a processos de erosão regressiva, comandada por rios consequentes com vales antecedente

Characterizing the Dual Transcriptomes of Woolly Apple Aphid, Eriosoma lanigerum (Hausmann), and its Host, Malus domestica (Borkh.), Across a Host Resistance Spectrum

Aphids are economically important, phloem-feeding insects that can cause substantial feeding damage to crops. The mechanisms underlying plant immunity to aphids are poorly characterized, but recent advances have shown a paradigm exists in plant immune signaling during aphid and pathogen attack. To overcome plant defenses, aphids, like other plant parasites, secrete effectors to modulate host processes that can lead to suppressed immunity. Emerging models of plant immunity combined with powerful sequencing technologies allow in-depth characterization of plant immune responses to aphids. In this thesis, I focus on the transcriptomic response of plants and aphids in the early stages of infestation across a host resistance spectrum to study the genes and processes that underlie plant defense responses. Also, I identify and characterize aphid candidate effectors to reveal insect proteins important for host colonization, and further refine our hypotheses of effector-mediated susceptibility. Through a systems biology approach, this thesis investigates the molecular underpinnings mediating the interaction between the domesticated apple, Malus domestica, and the woolly apple aphid, Eriosoma lanigerum. I found plant signal transduction, primary metabolism, photophosphorylation, cell wall modification and phytohormone mediated signaling were altered by woolly apple aphid feeding, and chloroplastic-ROS production and retrograde signaling may be linked to plant resistance phenotypes. Furthermore, host genes related to gall formation, such as the upregulation of xylogen-like arabinogalactan proteins and proteins involved in cell wall loosening, suggest xylem differentiation and cell expansion occur immediately upon colonization. Salivary gland effector characterization confirmed the presence of aphid effector orthologs such as C002, Shp and Armet. Furthermore, several enzymes possibly involved in reactive oxygen species scavenging and plant cell wall degradation were also identified. Overall, the research improves our understanding of apple transcriptional responses to aphid feeding, identifies woolly apple aphid candidate effectors that likely alter host processes, and provides new hypotheses for the mechanisms of gall induction by this iconic pest of apple

Clear-cut free forestry among private forest owners in southern Sweden

Swedish forestry is dominated by the clear-cutting system. The use of alternative methods such as clear-cut free forestry is becoming of greater interest. The Swedish forest agency have a wish for a more varied forestry management and are currently working with programs to promote these kind of management methods. Although the interest is increasing there are so far few forest owners who manage their forest in this way, and the knowledge about their motivations and practice is scarce. To get a better understanding about these forest owners this study aims to answer the following questions; (I) What is clear-cut free forestry from the owners perception? (II) What motive explains private owners’ interest in clear-cut free forestry? (III) Information and advice – What is accessible and where, and how do the FOs’ perceive it? The study is based on qualitative interviews analyzed with thematic analysis. In total 9 private forest owners in the south of Sweden were interviewed. These forest owners were all managing or planning to manage all or parts of their forest clear-cut free. This study shows that there seems to be an inconsistency when it comes to the terminology describing the management method; many of the forest owners seem to not know exactly what terminology to use, or if everyone they talk to will understand what the terminology means. One of the main motives for using clear-cut free methods is tradition; the forest has been managed in this way for a long time. Other important factors are economy, recreation and avoiding clear-cuts. The challenges for these forest owners are mainly the skepticism they perceive when seeking counselling, and also the machine operators lack of knowledge and understanding. In order to continue increasing the interest and use of clear-cut free forestry this could be important focus areas

Lost-and-found Photos: Practices and Perceptions

Personal photographs become separated from their original owners in a number of ways, due to time or tragedy, sometimes ending up in strangers’ hands. Dealers, collectors, curators, bloggers, scholars, and families actively seek what are frequently called “orphaned,” “abandoned,” or “found” photos and present them to the public in multiple formats. This dissertation offers an analysis of the practices and perceptions that surround these presentations, and it argues for use of a more inclusive term (“lost-and-found”) to describe personal photos that are connected to both finders and losers. Data were collected in three primary ways: (1) examination of the current contexts in which “lost” photos appear (e.g. books, websites, newspapers), (2) interviews with collectors of “lost” photos, and (3) the project’s website, designed to collect anecdotes from those affected by “lost” photos. Dominating this field of study are the perspectives of those who find personal photographs. The choices photo-finders make regarding the presentation and interpretation of photographs differ in clear ways, enabling me to group their practices within five categories which are evident across all formats examined in this study: Museum Curator, Archivist/Preservationist, Essayist/Editor, Reuniter, and Dealer. What unites practitioners across these discrete categories is the act of compiling and displaying “lost” photos within public archives, where new presentations of old photos invite myriad interpretations, conversations, and possibilities. Since the perspectives of those who have lost personal photographs have been largely missing from this field of study, I created tools to capture the viewpoints of photo “losers.” The project’s website, Lostandfoundphotos.org, provided a space in which contributors shared stories of personal photos they had lost, challenging notions of finder-collectors who often see themselves as the sole appreciators of “lost” photos’ true value. Most importantly, this project gave a literal voice to photo-losers through an audio component—a voicemail system which recorded contributors’ stories of lost personal photographs. This aural element offers a new medium for the examination of the visual, and it provides an emotional depth which, it is hoped, may inspire an enlargement of lost-and-found photography practices to accommodate the perspectives of both finders and losers

Fourier Transform Multiple Quantum Nuclear Magnetic Resonance

The excitation and detection of multiple quantum transitions in systems of coupled spins offers, among other advantages, an increase in resolution over single quantum n.m.r. since the number of lines decreases as the order of the transition increases. This paper reviews the motivation for detecting multiple quantum transitions by a Fourier transform experiment and describes an experimental approach to high resolution multiple quantum spectra in dipolar systems along with results on some protonated liquid crystal systems. A simple operator formalism for the essential features of the time development is presented and some applications in progress are discussed

Rationalising sequence selection by ligand assemblies in the DNA minor groove : the case for thiazotropsin A

DNA-sequence and structure dependence on the formation of minor groove complexes at 5′-XCTAGY-3′ by the short lexitropsin thiazotropsin A are explored based on NMR spectroscopy, isothermal titration calorimetry (ITC), circular dichroism (CD) and qualitative molecular modeling. The structure and solution behaviour of the complexes are similar whether X = A, T, C or G and Z = T, A, I or C, CCTAGI being thermodynamically the most favoured (ΔG = -11.1 ± 0.1 kcal.mol-1). Binding site selectivity observed by NMR for ACTAGT in the presence of TCTAGA when both accessible sequences are concatenated in a 15-mer DNA duplex construct is consistent with thermodynamic parameters (ΙΔGΙACTAGT > ΙΔGΙTCTAGA) measured separately for the binding sites and with predictions from modeling studies. Steric bulk in the minor groove for Y = G causes unfavourable ligand-DNA interactions reflected in lower Gibbs free energy of binding (ΔG = -8.5 ± 0.01 kcal.mol-1). ITC and CD data establish that thiazotropsin A binds the ODNs with binding constants between 106 and 108 M-1 and reveal that binding is driven enthalpically through hydrogen bond formation and van der Waals interactions. The consequences of these findings are considered with respect to ligand self-association and the energetics responsible for driving DNA recognition by small molecule DNA minor groove binder

The Main Central thrust and the South Tibetan detachment in the Dadeldhura klippe (West Nepal): New insights for the evolution of the Himalayan metamorphic core

Abstract HKT-ISTP 2013 A