Honors Projects for Microbiology

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    Intrauterine Growth Restriction in Babies Born to Cameroonian HIV-Positive Women: Identification of Possible Mechanisms Responsible for Low Birth Weight
    (University of Hawaii at Manoa, 2015-08) Rasay, Shayne Janne Jossef Dumalanta ; Taylor, Diane W. ; Microbiology
    HIV increases the risk of intrauterine growth restriction (IUGR), which results in the delivery of low birth weight (LBW) babies, who are 40 times more likely to die during their first year of life. However, the mechanism(s) for IUGR among HIV-exposed newborns remain unknown. In addition to socioeconomic and cultural factors, several hypotheses have been proposed to explain the biological component of IUGR. These include reduced 1) placental angiogenesis and vasculogenesis, 2) production of fetal growth hormones, and 3) transportation of nutrients. The first two hypotheses were examined in this investigation. To evaluate altered vessel formation, placental plasma levels of angiopoietins, ANG-1 and ANG-2, and galectin-13 were measured. Levels of insulin-like growth factor-1 (IGF-1) and one of its binding proteins, IGFBP-1, were measured to evaluate growth hormone dysregulation. In this case-control study, 21 HIV-positive and 30 HIV-negative pregnant mothers were recruited at delivery in the Central Hospital of Yaoundé, Cameroon, Africa. Results showed that biomarker levels in HIV-negative women were similar to literature values for healthy adults; but no significant differences were observed among the different groups. However a statistically significant (p=0.028) declining pattern of galectin-13 levels was noted as the severity of HIV infection increased. Overall, our results suggest that decreased angiogenesis and reduced production of growth factors may not cause LBW, but the dysregulation of maternal vascular development may play a role. Further studies using additional biomarkers are needed to identify the combination of social, economic and biological risk factors that increase the risk of HIV-associated LBW babies.
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    Enhancing the immunogenicity of a P. falciparum MSP1-19 malaria vaccine using a putative MSP1-33 T helper epitope
    (University of Hawaii at Manoa, 2015-05) Hokama, Acasia ; Hui, George ; Microbiology
    Developing an efficacious vaccine for the vector-borne infectious disease, Malaria, remains a top priority for disease control. The P. falciparum Merozoite Surface Protein 1(MSP1) is a leading blood-stage malaria vaccine candidate, and anti-MSP1 antibodies have been found to be important in providing protection against blood infections. MSP1 (195 kDa) goes through a number of proteolytic cleavage events to produce a 42-kDa fragment, which is further cleaved into 33-kDa (MSP1-33) and 19-kDa (MSP1-19) fragments. Although antibodies against MSP1-19 are protective, the MSP1-19 molecule alone cannot induce broad immune responsiveness due to lack of T helper epitopes on this protein fragment. We have recently identified four putative T epitopes on MSP1-33 that may enhance the quantity and quality of antibody responses to MSP1-19. We hypothesize that selective inclusion of one or more of these epitopes will have a measurable effect on the immunogenicity of MSP1-19. As proof of principle, we chose one of these epitopes to construct a new MSP1 vaccine by linking it to MSP1-19 via recombinant protein expression approach. The ability of this epitope to enhance the immunogenicity of MSP1-19 was examined in outbred mice in terms of production of high antibody titer, parasite growth inhibitory antibodies, and broad vaccine responsiveness. The recombinant protein tested produced a higher percentage of antibody responders than the native protein. The levels of Il-4 produced by antigen stimulation inferred that a TH2 response was also stimulated. These studies will hopefully lead to a rational approach to develop a more effective human malaria MSP1-42 vaccine.
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    Visualization of the tissue-specific promoter activity of the genes encoding protein disulfide isomerase-7, -12 and -13 in Arabidopsis thaliana
    (University of Hawaii at Manoa, 2014-09-26) Wong, Katharine ; Christopher, David ; Microbiology
    For proteins to properly carry out their functions, they must be folded correctly. Protein disulfide isomerases (PDIs) assist protein folding by catalyzing the formation and/or rearrangement of disulfide bonds between cysteine residues in newly- synthesized polypeptides. The goal of the project is to characterize the expression patterns of three PDI genes in the model plant, Arabidopsis thaliana. The Arabidopsis PDI (AtPDI) family consists of 13 members, the majority of which are found in the endoplasmic reticulum (ER), possess two catalytic domains, but lack transmembrane domains. In contrast, AtPDI7, AtPDI12 and AtPDI13 are unusual PDIs because they are primarily located at the Golgi apparatus, and possess two transmembrane domains and only one catalytic domain. Using the β-glucuronidase (GUS) reporter system, these three PDI genes were determined to have distinct tissue-regulated expression patterns. The AtPDI7 promoter was primarily active in developing tissues, while the AtPDI12 promoter was active in pollen, stipules, developing seeds, and the vasculature of roots. The AtPDI13 promoter activity was restricted to pollen and stipules. Interestingly, the AtPDI12 promoter was also inducible at the root tip by the plant hormone, auxin. The variable GUS staining patterns imply that there may be partial functional specificity between AtPDI7, AtPDI12, and AtPDI13. Further characterization of the tissue-specific expression of these PDIs would contribute in the understanding of how the different members of the PDI family each contribute to the process of protein folding in organisms.
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    Vibrio coralliilyticus strain OCN014 is the Etiological Agent of Acropora White Syndrome at Palmyra Atoll
    (University of Hawaii at Manoa, 2014-09-26) Poscablo, Donna ; Callahan, Sean ; Microbiology
    Corals play an important role in marine ecosystems by providing a habitat for many members of the reef community. Threats such as coral disease have pushed many reefs past the point of recovery and are lost forever. Investigation of coral disease outbreaks at Palmyra Atoll in 2010 and 2011 resulted in the isolation of Vibrio sp. OCN014 from diseased Acropora cytherea. OCN014 was proposed as the pathogen responsible for the disease Acropora white syndrome (AWS), which affects Acropora spp. throughout the atoll. In this study, Koch’s postulates were applied to demonstrate OCN014 as the etiological agent of AWS. OCN014 was determined to be a strain of Vibrio coralliilyticus, a species of bacteria previously shown to cause disease in coral. Under laboratory conditions, infections by OCN014 were found to be temperature dependent, with infections observed at 29 °C and none at 25 °C. The genome of OCN014 was sequenced and compared to a previously published genome of the V. coralliilyticus strain type strain BAA-450, which has also been shown to be temperature sensitive. A genetic system was developed to screen for genes which are differently expressed at 25 and 29 °C to identify potential regulators of OCN014 virulence.
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    Investigating the Role of Epigenetics on the Anti-Cancer Activity of Noni (Morinda citrifolia)
    (University of Hawaii at Manoa, 2014-09-26) Avilez, Kekaihalai ; Maunakea, Alika ; Microbiology
    Inherent in the traditional native Hawaiian concept of health is the understanding that environmental factors, including nutrition and diet, trans-generationally impact health outcomes. Epigenetic mechanisms now explain the molecular links between these environmental factors and health outcomes. Noni (Morinda citrifolia) has been employed for centuries by Kahuna lāʻau lapaʻau (medical practioners) to address many health ailments, including cancer. Modern studies abound validate the efficacy of noni for cancer treatment. Consistent with the traditional concept, we hypothesize that epigenetic mechanisms underlie the well-established anti-cancer effects of noni. Thus, we propose to examine the global and genome-wide epigenomic patterns of the colon cancer cell line HCT-116 before and after treatment with noni. Using Western blotting techniques, we will measure global levels of DNA methylation and histone modifications in treated and untreated cells. We will next employ state of the art technologies to identify, characterize, and integrate genome-wide DNA methylation and gene expression alterations in HCT- 116 cells in response to noni. We anticipate that epigenetically labile sites, in particular hyper-methylated tumor-suppressor gene promoters, will be responsive to noni treatment, which could lead to changes in gene expression. We will confirm cases of noni-induced DNA demethylation by comparing these data with that of HCT-116 cells genetically deficient for DNA methylation. Results from this study will establish, for the first time, a link between the anti-tumor effects of noni and epigenetic gene regulation, demonstrating that the traditional native Hawaiian concept of health included a mechanistic rationale for the role of the environment on physical health.