Coral reefs are a critical resource to developing and developed nations world wide. Providing shelter, food, monetary value, and a vast resource of ecological wealth, the corals of the reefs underpin an entire ecosystem. Climate change, driven by increased greenhouse gases, is raising the temperature of Earth’s waters and atmosphere, while making the planet’s oceans increasingly acidic. Brightly lit and increasingly warm tropical waters present a potentially challenging environment in which scleractinian corals grow. In attempting to cope with the competing stresses of intense photon flux density (PFD) and anomalously high sea surface temperatures, corals and dinoflagellates exhibit myriad biochemical and physiological adaptations. Pocilloporins, a diverse group of non-fluorescent green fluorescent protein (GFP) homologs found across Cnidaria and beyond, are one such adaptation within the tissues of heavily pigmented scleractinian corals. Chemically unique amongst pigments, GFP-like pigments exist as pure protein chromophores and exhibit little to no cytotoxicity when naturally occurring. This non-fluorescent class of GFP-like pigments has found popularity in biochemical and biotechnological applications, though an ecological and evolutionary explanation for the heavy conservation of pocilloporins across a broad range of scleractinian corals and related cnidaria is still a subject of scientific research and debate. This thesis supports the hypothesis that pocilloporins act as a naturally occurring photoprotective pigment in reef-building corals, specifically acting to filter and regulate the light environment within coral polyps. In examining the role of pocilloporins in Scleractinia, the need to examine environmental sources of pigment production induction and suppression, the localization of pigments within coral tissues and cells, and the ability of coral colonies to direct resource allocation with regards to pocilloporin production were identified as lines of inquiry. Briefly, for experiments examining either pocilloporin induction or suppression, the following aspects were studied: holobiont responses in the form of mRNA signal expression, host pigment isolation and analysis, dinoflagellate density and pigmentation sampling, and chlorophyll fluorescence of live corals. Blue morph Acropora aspera, common to the reef flat of Heron Island (Great Barrier Reef, Australia), were subjected to 99% shade and thermal bleaching threshold temperatures in separate attempts to suppress pocilloporin expression, while red morph Montipora monasteriata was transplanted at equivalent depth from their natural cave environments to exposed portions of the spur and groove formations of the northern face of Wistari Reef (Great Barrier Reef, Australia). Both ambient temperature and heat-stressed A. aspera were concurrently collected during the thermal stress experiment and placed in preservatives for immuno-histochemical localization of pocilloporins with their tissues. Finally, radio-labelled glycine, a very common amino acid in the primary sequence of pocilloporin, was injected into artificially injured tan morph Montipora monasteriata, also on the northern face of Wistrai Reef to study the uptake of dissolved organic materials (DOM) and incorporation of metabolic resources into newly generated pigments. Pocilloporins proved easier to induce in this work than suppress, and the location of these pigments in A. aspera tissues suggests a potential mechanism. The data demonstrated the presence of pocilloporins in the most directly exposed epidermal and gastrodermal tissues of the coral polyp, specifically the outermost layers of epidermis and gastrodermal layers bordering directly upon the gastrovascular cavity. Closer inspection through anti-pocilloporin-gold stained TEM images was highly suggestive of pocilloporin secretion in coral mucus, a theory separately supported by observations of coral mucus in collected live corals. Neither suppression experiment induced heavy mucus sloughing in A. aspera, so despite multi-fold reductions in pocilloporin mRNA as a result of applied stimuli, the continued presence of pocilloporin aaCP592 in blue morph A. aspera is not surprising. Conversely, pocilloporin msCP576 in plating Montipora monasteriata was induced in response to both general increases in PFD and specific increases of PFD at the sites of physical injury. Additionally, tan morph Montipora monasteriata demonstrated the capacity to collect and allocate DOM from the environment to assist in the production of new pigments and tissues, an energetically expensive process. The reduction of the orange-red spectrum in favour of the blue light ranges is generally beneficial to the photosynthetic systems of both higher plants and the resident dinoflagellates of corals. msCP576 and aa592, both positively identified as pocilloporins within this work, absorb within the orange-red region and apparently act as a photoprotective filter in all exposed surfaces of heavily pigmented corals, enhancing the blue spectrum of incident and reflected PFD and generally regulating the internal light environment.

Thesis (Ph. D.)--Cornell University, May, 2007. / Vita. Includes bibliographical references (leaves 101-107).

The human gammaherpesviruses EBV and KSHV realize their oncogenic potential during latent infection. The species specificity of the human gammaherpesviruses has hindered the study of latency in animal models. Murine gammaherpesvirus MHV-68 (MHV-68) may be used as a representative gammaherpesvirus for the study of latency. The goal was to establish an in vitro model of MHV-68 latency using replication defective MHV-68. ORF50 has been identified as the major viral trans-activator essential for entry into the lytic replication cycle and necessary and sufficient for reactivation of MHV-68 virus from latency. ORF50 null mutants (A50) can theoretically be used to infect cells in vitro to facilitate an analysis of virus gene expression and episome maintenance during latency. In this project A50 mutants containing the luciferase or green fluorescence protein (GFP) under OW50 promoter control were used to infect a variety of cell types. 3T3 fibroblasts are a permissive cell line and were used for an initial characterization of the ability of A50 MHV-68 to establish latency. B lymphocytes and macrophages are the major reservoirs of persistence in vivo thus the ability of A50 mutants to establish latency in NSO B and RAW macrophage cell lines was explored. Latency was readily established and maintained in 3T3 and RAW cells. The low infectability of NSO B- cells restricted the utility of this cell line in studies of latency. Examination of patterns of lytic and latent transcription in 3T3 and RAW cells coordinately infected with A50 MHV-68 revealed reactivation efficiencies of 40-60%. Following long-term passage A50 exhibited stable transcription of two latency related genes M2 and ORF73, with episomal maintenance of the viral genome, in the absence of contaminating lytic infection. The results demonstrate the utility of A50 mutants for studies of gammaherpesvirus latency in vivo.

Uveal melanoma is the most common primary malignant intraocular tumour in adults and despite advances in treatment of the primary tumour, the 10-year survival rate remains unchanged. The most frequent cause of death for patients of this disease is liver metastases. Removal of the primary tumour before clinical presentation of metastases, however, has no effect on patient outcome. / In order to understand the interactions between single malignant cells or sub-clinical metastases and affected organs, we have successfully developed a novel animal model of uveal melanoma. We utilized the unique properties of green fluorescent protein, a skin-flap in vivo imaging technique, and nude mice to accomplish this goal. The precision of green fluorescent protein imaging has allowed us to observe single cells interacting with organ tissues and reveal that these malignant cells are only capable of surviving in the liver.

Colleotrichum graminicola is the causal agent of anthracnose stalk rot, and is one of the most common and aggressive pathogens of maize. The goal of my Ph.D. project was to contribute to a better understanding of the biology of the interaction between C. graminicola and its host. C. graminicola produces two type of asexual spores: one is produced on the surface of infected tissues and is thought to be involved in the spread of the disease in the field. The second type of spore, oval in shape, is produced inside the infected plant tissues, and was believed to be involved in the movement of the pathogen inside the plant tissues via the vascular system. I tested this hypothesis with both cytological and molecular approaches. I used strains of C. graminicola expressing green fluorescent proteins (GFP) to inoculate wounded plants, and followed the development of the pathogen over time. This study revealed that C. graminicola is not a vascular pathogen. C. graminicola primarily moved through the rind and vascular fibers. Oval spores were produced in colonized parenchyma cells and remained dormant, and did not appear to be involved in the movement of the pathogen, at least during the early stages of the disease development. I also studied pathogen ingress in the absence of a wound. I inoculated unwounded plants with the GFP expressing strains. C. graminicola efficiently colonized the epidermis and, given enough time, penetrated and colonized the deeper parenchyma tissues, after first moving through the fibers. To further test the role of sporulation in colonization of maize tissues, I used targeted mutagenesis to disrupt a major gene known to regulate sporulation and vegetative growth in several other fungi. The gene Cgg1, orthologue of the A. nidulans fadA, was disrupted using the split marker method. The Cgg1 mutants were less pathogenic than the wildtype to wounded plants. This was associated with an apparent increase in production of spores and primary infection hyphae. This suggests that Cgg1 signaling pathway plays a role in maximizing colonization of host tissues, and that this involves negative regulation of sporulation and primary hyphae production in planta.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

No description available.

Thesis (Ph.D. in Cell Biology, Stem Cells, & Development) -- University of Colorado Denver, 2008. / Typescript. Includes bibliographical references (leaves 138-155). Free to UCD Anschutz Medical Campus. Online version available via ProQuest Digital Dissertations;

Orientador: Selma Giorgio / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-17T13:17:36Z (GMT). No. of bitstreams: 1 Costa_SolangedosSantos_M.pdf: 4660323 bytes, checksum: 5aef15cb049a82091dd076c48c1f6f2b (MD5) Previous issue date: 2010 / Mestrado / Parasitologia / Mestre em Parasitologia

The endoplasmic reticulum stress response, also known as the unfolded protein response (UPR), has been implicated in the normal physiology of immune defense and in several disorders, including diabetes, cancer, and neurodegenerative disease. Here, we show that the apoptotic receptor CED-1 and a network of PQN/ABU proteins involved in a noncanonical UPR response are required for proper defense to pathogen infection in Caenorhabditis elegans. A full-genome microarray analysis indicates that CED-1 functions to activate the expression of pqn/abu genes. We also show that ced-1 and pqn/abu genes are required for the survival of C. elegans exposed to live Salmonella enterica, and that overexpression of pqn/abu genes confers protection against pathogen-mediated killing. The results indicate that unfolded protein response genes, regulated in a CED-1-dependent manner, are involved in the C. elegans immune response to live bacteria. / Dissertation