A self-assembling peptide scaffold functionalized for use with neural stem cells

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2005.Includes bibliographical references (leaves 33-35).The performance of a biological scaffold formed by the self-assembling peptide RADA16 is comparable to the most commonly used synthetic materials employed in the culture of neural stem cells. Furthermore, improvements in the performance of RADA16 have recently been made by appending the self-assembling peptide sequence with various functional motifs from naturally occurring proteins. The focus of this work is to further analyze the performance of these functionalized self-assembling peptide scaffolds when used for the culture of neural stem cells, and to characterize these newly developed materials for comparison with RADA16. The effect of the functional motifs on the structure of the peptide scaffold was evaluated with circular dichroism and scanning electron microscopy, and the mechanical properties of the peptide scaffolds were examined through theological analysis. The functionalized peptides were found to have lower percentages of beta-sheet structure as well as reduced storage moduli in comparison with RADA16. SEM images confirmed the ability of the functionalized peptides to form three-dimensional nanofiber scaffolds capable of encompassing, neural stem cells. Three-dimensional cell culture techniques were used to evaluate the ability of the functionalized peptide scaffolds to promote neural stem cell proliferation, and a scaffold formed by the combination of different functionalized peptides was found to increase the proliferation of neural stem cells in comparison to non-functionalized RADA 16.by Angus M. Hucknall.S.M

“Indians, you had life – your white destroyers only possess things”: Situating Networks of Indigeneity in the Anti-Colonial Activism of Revolutionary Ireland

In 1910, Roger Casement embarked on a voyage into the upper Amazon to officially investigate reports of crimes against humanity committed by a British-financed, Peruvian rubber company. The official report of his findings, published as a parliamentary Blue Book, provoked considerable diplomatic reverberations between Washington, Westminster and Rome. It resulted in a significant shift in international attitudes towards indigenous peoples. The journal kept by Casement during his months in the Amazon demonstrates not merely his own scathing interrogation of the distorting constructs of colonial reality, but a complex recognition of indigenous culture rooted in his own conception of “Irishness.” His defense of “savagery” underscored both his critique of “civilization” and the justification of his tragic revolutionary turn. From 1913, he began to connect the fate of the Amazindian with the lot of Connemara “islanders” suffering from an outbreak of typhus. Later, at his treason trial, his own call to transnational resistance is encoded within the logic: “If there be no right of rebellion against a state of things thatno savage tribe would endure without resistance, then I am sure that it is a better thing for men to fight and die without right than to live in such a state of things as this.” This article will reveal the identification with “indigeneity” and the configurations of power evident in the transnational discourse on “indigenous peoples” which was integral to the intellectual formation of anticolonialism in revolutionary Ireland. Through the investigations of Casement, and the establishment of the African Society by the historian Alice Stopford Green, this identification expanded into an explicit recognition of indigenous rights and knowledge and the advocating of a responsibility to defend such rights and knowledge, once independence had been achieved

Unframing the Black Diaries of Roger Casement

For a century now, the disputed frontier region of the upper Amazon– bordering Brazil, Peru, Colombia and Bolivia – has been the subject for one of the most persistent controversies in Irish history. In 1910 and 1911 the British Consul, Roger Casement (1864-1916) undertook two separate voyages up the Amazon to investigate crimes against humanity: the decimation of people and environment resulting from the extractive rubber industry. These investigations ultimately helped the South American rubber boom go bust and persuaded international investors to switch interests to the new Anglo-Dutch rubber plantation economy of Southeast Asia. But since Casement’s execution in 1916 for his part in the Easter rising, a bitter controversy has raged over his reputationand the authenticity of the so-called Black Diaries. Three of these contested records configure with his Amazon voyages and are sources for analysing an important socio-economic tipping point in Latin American history. In 1997 & 2003 I edited two volumes of documents relevant to his Amazon investigations which formed part of an on-going methodological inquiry enabling a new and alternative textual reading of the Black Diaries and the re-evaluation of Casement as a critical voice in Irish and World history.1 The publication of these edited volumes reawakened a long-standing argument suggesting that the diaries areforgeries. In 2008 a comprehensive new biography was published on Roger Casement, which went to some length to discredit my nascent argument. This article is the first part of my response to the biographer, Séamas Ó Síocháin’s Roger Casement: Imperialist, Rebel, Revolutionary

Histories of ‘Red Rubber’ Revisited: Roger Casement’s Critique of Empire

The Irish literary critic Declan Kiberd has commented how the generation of Irish women and men who rebelled in 1916 against British authority in Ireland were more concerned with the future than they were with the past. Understanding the intellectual complexity of their radical critique is still work in progress. In the case of Roger Casement, it has taken a century to pass for a dialogue on human rights law and crimes against humanity to develop and prosper in order for his own achievement to be recognised. Casement’s name will be forever linked with the exposé of desperate atrocities committed in the three decades before the outbreak of the first world war. The insatiable commercial demand for extractive rubber by the industrial world to nourish the next generation of transport and electrification led to an atrocity that defiesmeasurement in terms of human suffering and environmental damage. This trans-Atlantic tragedy has in many ways defined the modern emergence of both sub-Saharan Africa and the Amazon. Retrieving the history of the rubber resource wars remains a challenge for those who contest the self-justifying narratives of western progress. At the picentre of Casement’s investigations was his nuanced critique of empire rooted in his scrutiny of racial and genderbased violence. His methods of investigation and his deeper critique of the imperial order is as relevant today – in this faltering age of globalization – as it was a century ago, when Casement faced his accusers and was executed for his challenge to imperial systems on a scaffold in central London.Keywords: Roger Casement, rubber, human rights, Putumayo

Roger Casement in Argentina

Roger Casement made two journeys to Argentina: the first was in 1907 and the second was in 1910. Little is known about either trip beyond a few fragmentary references in letters and some encrypted entries in the contested Black Diaries. Nonetheless, these traces would suggest that Casement was connected into a vibrant Irish-Argentinian network that played a vital role in the independence struggle before and after 1916. Through reconstructing evidence of these visits and locating his friendships within Ireland’s broader transnational struggle, this essay excavates a dimension of informal diplomacy that prepared the ground for the  emergence of Irish foreign policy after 1919

PEST sequences in the malaria parasite Plasmodium falciparum: a genomic study

BACKGROUND: Inhibitors of the protease calpain are known to have selectively toxic effects on Plasmodium falciparum. The enzyme has a natural inhibitor calpastatin and in eukaryotes is responsible for turnover of proteins containing short sequences enriched in certain amino acids (PEST sequences). The genome of P. falciparum was searched for this protease, its natural inhibitor and putative substrates. METHODS: The publicly available P. falciparum genome was found to have too many errors to permit reliable analysis. An earlier annotation of chromosome 2 was instead examined. PEST scores were determined for all annotated proteins. The published genome was searched for calpain and calpastatin homologs. RESULTS: Typical PEST sequences were found in 13% of the proteins on chromosome 2, including a surprising number of cell-surface proteins. The annotated calpain gene has a non-biological "intron" that appears to have been created to avoid an unrecognized frameshift. Only the catalytic domain has significant similarity with the vertebrate calpains. No calpastatin homologs were found in the published annotation. CONCLUSION: A calpain gene is present in the genome and many putative substrates of this enzyme have been found. Calpastatin homologs may be found once the re-annotation is completed. Given the selective toxicity of calpain inhibitors, this enzyme may be worth exploring further as a potential drug target

Quantifying submarine channel morphology and kinematics on structurally complex slopes: examples from the Niger Delta

Submarine channels form pronounced morphological features on the seafloor and play an important role in shaping the stratigraphic record. Over the last two decades, their morphology and architectural evolution have been studied in detail using a range of modern and ancient examples. While structural deformation is recognised as a major control, the temporal and spatial complexity associated with these systems means aspects of submarine channel dynamics and how their geomorphic expression translates into time-integrated sedimentary architecture, remain poorly understood. For example, structurally driven changes in slope morphology may locally enhance or diminish a channel’s ability to incise, aggrade and migrate laterally. In this thesis, I explore the sensitivity of submarine channel morphology to structural deformation and evaluate how channel-structure interactions are recorded in seismic stratigraphic architecture. I use novel seismic attribute analysis alongside concepts from landscape dynamics to provide quantitative insights into how the growth of structure on the southern Niger Delta slope has influenced submarine channel morphology and time-integrated stratigraphic architecture. From a 3D, time-migrated seismic reflection volume, I quantify a range of morphometric parameters including, channel gradient, width, depth, sinuosity, curvature, and stratigraphic mobility, on a number of modern and ancient submarine channel systems as they interact with structure. My results show that submarine channel morphology and longitudinal profile are unambiguously linked to the underlying structural template. The modern seafloor expression of submarine channels can be up to an order of magnitude higher aspect ratio and markedly more variable than their ancient, stratigraphic counterpart. Their depositional architectures are composite stratigraphic features that record the morphological response to spatial and temporal variations in structural growth rate. Based on this, three end-member styles of submarine channel architecture are recognised on structured slopes: pre-channel structural bathymetry, coeval positive relief, and coeval negative relief. This thesis quantifies how submarine channel systems integrate kinematic processes at the scale of the fundamental architectural unit, a channel element, and documents the systematic change in channel element kinematics on structured segments of the slope. My observations demonstrate the sensitivity of submarine channels to structural deformation and help us to constrain some of the most important sediment transport systems on planet Earth.Open Acces

Ocean Acidification and Seasonal Temperatures Counter Positive Novel Species Interaction and Warming Effects on Tropicalising Temperate Fish Communities

Anthropogenic warming has facilitated the redistribution of species globally. Many tropical species have shifted their ranges poleward either to escape thermally unsuitable conditions or to invade previously inaccessible temperate environments. Climate-driven species redistributions have facilitated range-shifting and local species to interact for available resources. These novel species interactions can modify the pace of species range extensions. In Australia, over 150 tropical fish species have been observed moving poleward into temperate marine ecosystems but often fail to establish due to hostile conditions (winter temperatures and environmental novelty). However, ocean warming could minimise lethal winter effects on range-extending tropical fishes, allowing them to establish at temperate latitudes in the near future. This thesis provides empirical and experimental evidence that current and future climatic conditions (ocean acidification and warming) and novel species interactions can modify the pace of tropicalisation in temperate marine ecosystems and highlights the capacity of local temperate fish communities to respond to tropical fish range extensions. By using a climate-manipulated laboratory experiment, I reveal that ocean acidification might slow tropicalisation through degradation of the shoaling performance of novel tropical-temperate fish shoals (Chapter 2). In addition, I show that future winter conditions negatively affect tropical fish behavioural repertoire and physiological function in temperate ecosystems (Chapters 3 and 4). In contrast, I demonstrate that the temperate fish behaviour remained unchanged but experienced increased growth and physiological performance under future winter conditions compared to current and future summer conditions (Chapters 3 and 4), which could seasonally modify tropical-temperate interactions. I further reveal that tropical fish entering novel temperate environments trade off foraging efficiency for predator vigilance, independent of novel shoaling interactions (mixed-species shoaling). However, novel species interactions can enhance tropical fish foraging, which may allow them to perform better at their cold-temperate range edges (Chapter 5). While present-day lethal winter temperatures and novel temperate environmental conditions slow tropicalisation, the overall effect of ocean warming and positive species interactions will facilitate the tropicalisation of temperate waters in a future ocean. However, future winter temperatures and ocean acidification could limit tropical fish performance at temperate latitudes.Thesis (Ph.D.) -- University of Adelaide, School of Biological Sciences, 202

Electrocortical components of anticipation and consumption in a monetary incentive delay task

In order to improve our understanding of the components that reflect functionally important processes during reward anticipation and consumption, we used principle components analyses (PCA) to separate and quantify averaged ERP data obtained from each stage of a modified monetary incentive delay (MID) task. Although a small number of recent ERP studies have reported that reward and loss cues potentiate ERPs during anticipation, action preparation, and consummatory stages of reward processing, these findings are inconsistent due to temporal and spatial overlap between the relevant electrophysiological components. Our results show three components following cue presentation are sensitive to incentive cues (N1, P3a, P3b). In contrast to previous research, reward‐related enhancement occurred only in the P3b, with earlier components more sensitive to break‐even and loss cues. During feedback anticipation, we observed a lateralized centroparietal negativity that was sensitive to response hand but not cue type. We also show that use of PCA on ERPs reflecting reward consumption successfully separates the reward positivity from the independently modulated feedback‐P3. Last, we observe for the first time a new reward consumption component: a late negativity distributed over the left frontal pole. This component appears to be sensitive to response hand, especially in the context of monetary gain. These results illustrate that the time course and sensitivities of electrophysiological activity that follows incentive cues do not follow a simple heuristic in which reward incentive cues produce enhanced activity at all stages and substages