1988 — 1990 |
Ray, Thomas L |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Role of Candida Acid Proteinase in Pathogenesis
The aim of this proposal is to elucidate the extracellular acid proteinase of Candida spp. (CAP) as a constitutive pathogenic factor in Candida infections by demonstrating: 1) CAP participation in invasion of the skin by Candida in experimental rodent models of cutaneous candidiasis; 2) CAP participation in protecting Candida blastospores from uptake and killing by phagocytic cells; 3) the prevalence of CAP both phenotypically and genomically, in pathogenic and commensal isolates of Candida species, and its correlation with pathogenic and virulent behavior. The role of CAP in cutaneous infections will be performed by studying CAP producing and non-producing isogenic isolates and strains of Candida in experimental rodent models of cutaneous candidiasis. Their ability to invade the epidermis, dermis and fat layers of skin will be assessed by light and electron microscopy for disruption or dissolution of the major proteins of skin, keratin and collagen, which are CAP substrates. CAP inhibition by pepstatin and neutralizing antibody, as well as supplementation with purified CAP, will be studied in these infections. The enzyme will be localized in infected tissue by immunofluorescent microscopy. The role of CAP protecting blastospores from phagocyte uptake and killing will be assessed by standard phagocytosis and killing assays of CAP-producing and non-producing isogenic isolates and species of Candida, in the presence and absence of pepstatin or neutralizing antibody, or supplemental active purified CAP. Direct cytotoxicity of CAP will be assessed by 51Cr-release assays of labelled monocyte, macrophages, and neutrophils. The prevalence of CAP in pathogenic and commensal isolates of Candida will be determined phenotypically by enzyme production in restrictive cultures, and genomically by Southern blot hybridization of restriction endonuclease digests of Candida DNA with a cDNA probe for the CAP encoding gene. Virulent behavior of the isolates will be confirmed in the experimental rodent model of cutaneous candidiasis. This study will characterize the participation of CAP in cutaneous invasion and phagocyte interactions of Candida organisms, demonstrating facilitation of tissue invasion and protection against host inflammatory response. This will be the first study to characterize a virulence factor in Candida species at the genetic level through molecular biology. Data may allow discrimination of commensal and pathogenic isolates for diagnostic testing while revealing critical steps in pathogenesis amenable to therapeutic intervention.
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0.934 |
1989 — 1990 |
Ray, Thomas |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Morphometric and Phylogenetic Studies of Shoot Development in the Araceae
Members of the genus Araceae include morphologically and ecologically diverse tropical plants. In some genera, shoot development is altered allowing the plant to climb toward the forest canopy. Dr. Thomas Ray proposes to use state-of-the-art approaches to studying shoot and leaf development in various genera of aroids, in order to learn how different patterns of plant development have evolved. A microcomputer-based image analysis system will be used to measure shape and size of leaves and shoot organs, and these new data will be studied against the framework of ancestor-descendant relationships. The proposed research will reveal the evolutionary pathways that different developmental types have traversed. The proposed research has implications beyond the study of Araceae taxonomy and evolution. Biologists are keenly interested in how development is altered during evolution, and how development constrains the path that evolution may take. Dr. Ray's work will also broaden the application of computer-aided research in botany, and will provide new computer software to the community of evolutionary systematists.
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0.966 |
1992 — 1993 |
Ray, Thomas |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Computer Architectures For the Natural Evolution of Machine Code
The theme of this project is designing a computer architecture and operating system that will support the natural evolution of machine code. The primary computational objective is to experiment with a large number of variations on the successful architecture in order to find the optimal balance of computational power and evolvability.
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0.966 |
1993 — 1995 |
Ray, Thomas L |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Candida Acid Proteinase and Pathogenesis
Success of Candida as a pathogen may depend partly on high frequency switching between general phenotypes and their associated expression of hypothetical sets of virulence genes that in the composite (but not singularly) facilitate and constitute a strain's pathogenic behavior. One putative virulence factor, Candida acid proteinase (CAP), is differentially expressed by switch phenotypes, facilitates pathogenic behavior, and is a prime candidate for membership in the hypothetical set of Candida virulence genes. We ask: 1) Do specific switch phenotypes and their CAP secretion correlate with commensal or pathogenic behavior? 2) Do patient titers of CAP antibody or antigen correlate with infection, phenotypes and CAP secretion? 3) Do switch phenotypes and CAP secretion relate to observed and experimental pathogenic behavior? The project will determine if switch phenotypes and CAP discriminate between commensal and pathogenic Candida isolates, and correlate with human and experimental animal infections. 1. Quantitation of CAP Secretion by Commensal and Pathogenic Candida Isolates and Phenotypes. Commensal and pathogenic isolates and their phenotypes from normals and patients with candidiasis, will be obtained. CAP secretion of each phenotype will be assessed and correlated with 1) commensal or pathogenic behavior of isolates and switch phenotypes in patients and 2) the pathogenicity of phenotypes in experimental candidiasis. 2. CAP Antibody Response and Antigenic Presence in Mucocutaneous and Systemic Candidiasis. Sera of patients at risk to or with systemic candidiasis, or with mucocutaneous candidiasis and those with Candida colonization, will be obtained. CAP antibody and antigen will be measured by ELISA and latex agglutination. Tissue of infections will be tested for CAP deposits by immunofluorescent methods. CAP antigen in sera and tissue and CAP antibody titers will be correlated with clinical manifestations, the patient's isolate and switch phenotypes and their CAP secretion. Predictive values of CAP antibody and antigen titers in sera for infections will be determined. The secretion and presence of CAP in vivo with be correlated with infecting strains and switch phenotypes. 3. Pathogenicity of Candida Isolates and Their Switch Phenotypes in Experimental Candidiasis. Virulence of commensal and pathogenic isolates and switch phenotypes from Candida infections will be tested in murine models of candidiasis. Virulence will be correlated with isolate behavior in the patient of, origin, the switch phenotype used, and CAP secretion. This will demonstrate the role of switch phenotypes and CAP secretion in experimental infections to compare with clinical infections. Transitions from commensal to pathogenic phenotypes through switching and CAP secretion may be elucidated.
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0.934 |
1993 — 1996 |
Ray, Thomas |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Evolotion of Digital Organisms
This award will support the purchase of a computer workstation for the investigator, so that he may extend the complexity as well as the length of his studies. The investigator will study processes of population change and ecological patterns via computer simulations. The simulations are produced by machine code algorithms. In the process of these studies, the investigator will also be investigating means of developing (evolving) software for massively parallel machines.
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0.966 |
2016 — 2018 |
Ray, Thomas |
F32Activity Code Description: To provide postdoctoral research training to individuals to broaden their scientific background and extend their potential for research in specified health-related areas. |
Molecular & Cellular Cues For Circuit Assembly in Mouse Retina
SUMMARY The retina contains ~100 neuronal cell types, each of which contribute to visual processing by wiring together in distinct parallel circuits. The point of convergence for circuit determination resides in the inner plexiform layer (IPL) of the retina, where axons and dendrites from ganglion cells, bipolar cells, and amacrine cells coalesce to form a synaptic neuropil containing 10 distinct sublayers. Neurons belonging to the same circuit stratify distinct sublayers of the IPL to make circuit specific synaptic connections. The cellular and molecular cues that direct development of these layers are largely unknown but crucial to determining which neurons wire together. The objective of this application is to determine the developmental mechanisms that enable the formation of one specific circuit, the direction selective (DS) circuit. My central hypothesis is that starburst amacrine cells (SACs) create and organize the DS circuit, through interactions among themselves as well as with the arbors of other DS circuit cell types. The rationale for this work is that the DS circuit is not only of great importance to understanding organization of the IPL, but understanding how the DS circuit forms will elucidate the mechanisms used by circuits throughout the CNS. I have formulated two specific aims that will directly test my central hypothesis. Aim 1) Determine the mechanisms that initially create the DS circuit IPL sublayers. Our preliminary data suggests that SAC-SAC homotypic contact prompts stratification of the IPL. When MEGF10, a cell-surface molecule known to mediate SAC homotypic recognition, is removed, assembly of the circuit is delayed. Aim 2) Determine the mechanisms that recruit DS ganglion and bipolar cells to the DS layers of the IPL. We have discovered a mouse line that has SAC IPL projection errors. This unique tool enables me to determine if SACs recruit their synaptic partners, DS-circuit ganglion and bipolar cells, to the DS IPL sublayers. Together, these two aims will reveal the cellular and molecular mechanisms SACs use to initially stratify the IPL and direct assembly of the other DS cell types. The knowledge we gain from this study will contribute to our understanding of the mechanisms neurons in the CNS use to form cell type specific connections and will further our understanding of how the IPL develops. A thorough understanding of these processes will be required to eventually repair neural circuits after disease or injury.
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0.97 |