Mastergradsoppgaver i biologi (Helsefak)
DSpace/Manakin Repository
Mastergradsoppgaver i biologi (Helsefak)
Recent additions
-
Paunas, Teodora Ioana (Master thesis; Mastergradsoppgave, Sep-2011)[+][-]
Abstract: Coronary heart disease is the leading cause of death worldwide. Infarct size can be limited by interventions used after the ischemic event like the use of thrombolytic therapy or primary percutaneous coronary intervention. Paradoxically, however, the return of blood flow can also result in additional cardiac damage and complications, referred to as reperfusion injury. It has been shown that reperfusion injuries can be decreased by postconditioning- rapid intermittent interruptions of blood flow in the early phase of reperfusion, or post-treatment using various drug therapies which applied during reperfusion can reduce infarct size. H2S, a gas that is synthesized in mammalian tissue, has been reported to be cardioprotective during ischemia-reperfusion injury. The means by which H2S is cardioprotective during I/R are believed to be: the opening of the sarcolemmal KATP channel, the generation of antiapoptotic effects inside the cells as well as a direct antioxidant effect. Low levels of reactive oxygen species (ROS) are constantly produce within cells and play important roles in cell signaling, cellular homeostasis, differentiation and apoptosis. However an excessive increase in the level of ROS can be harmful and has been proposed to play crucial roles or contribute in the development of various diseases. The aim of our study was to investigate the effects of H2S in an acute ischemia-reperfusion model and to determine whether exogenous administration of H2S in both healthy rats and rats exposed to experimental models of cardiac disease influenced the production of ROS. In order to do this we established a method trough which we were able to measure the presence of ROS in heart tissue samples harvested from normal rats and rats with heart hypertrophy and ischemic heart disease. URI: http://hdl.handle.net/10037/3726 File(s) in this item: 1
thesis.pdf (1.535Mb) -
Adou, Koman Mireille Sophie Chinan (Master thesis; Mastergradsoppgave, Aug-2011)[+][-]
Abstract: Human polyomavirus BK (BKV) is a non enveloped virus with a double-stranded, circular DNA genome. BKV infects >70% of the human population world-wide. Infection occurs predominantly during childhood and the virus remains in a latent state throughout life in the immune competent individuals. In the context of immunosuppression, however, reactivation occurs and can lead to renal stenosis and interstitial nephritis in kidney transplant patients, and hemorrhagic cystitis in bone narrow transplant patients. Moreover, BKV has been associated with several human cancers, but its causal role remains disputed. One of BKV’s protein known as agnoprotein may play a role in these pathogenic processes. To develop antiviral therapy it is required to elucidate the exact biological function of this protein. One way to examine the function of agnoprotein is by identifying possible cellular interaction partners. Another way is to understand agnoprotein’s role in the viral life cycle. Thereto, we examined the interaction of agnoprotein with another viral protein, large T-antigen (LT-ag) and the functional implication of this interaction. First, we investigated the effect of agnoprotein on the transcriptional activity of LT-ag on the BKV early promoter by transient transfection studies in HEK293. Our results revealed that LT-ag affects BKV early promoter in a concentration-dependent manner with low concentrations of LT-ag inhibiting, while high concentrations stimulated BKV early promoter activity. Co-expression of agnoprotein repressed LT-ag-induced activation of the BKV early promoter, suggesting that agnoprotein may exert a negative regulatory effect on transactivation by LT-ag. To test whether agnoprotein mediates its effect through direct interaction with LT-ag, we studied a possible association between these proteins. GST pulldown, co-immunoprecipitation (in vivo and in vitro), and mammalian two hybrid studies confirmed an interaction between LT-ag and agnoprotein. URI: http://hdl.handle.net/10037/3568 File(s) in this item: 1
thesis.pdf (2.113Mb) -
Bohra, Pallavi (Master thesis; Mastergradsoppgave, 16-May-2011)[+][-]
Abstract: Starting with LacZ of Escherichia coli, coding for β-galactosidase, the aim of the thesis project is to apply in vitro directed evolution techniques to help create other glycosidic bond hydrolysis activities. This was done using the main β-galactosidase backbone with limited amino acid sequence change. Any altered glycosyl hydrolase activity would lead to changed substrate specificity. Moreover, genetic changes leading to improved beta-galactosidase activity was also investigated. Error-prone PCR was applied to the LacZ gene (β-galactosidase) to achieve the desired aims. The technique used to introduce random mutagenesis was based on modifications of method developed by Xu et al., 1999.Optimization was performed with DNA polymerase selection, PCR conditions and various Mn and dITP concentrations to obtain best amplified PCR product for random mutagenesis library construction. Plasmid pTZ1 containing the entire coding sequence of LacZ was used a whole plasmid random Mutagenesis library construction strategy. The complete pTZ1 plasmid sequence had to be done in order to help establish a framework for primer design and establish a complete restriction map of the plasmid including the lacZ gene. The sequence analysis of the plasmid revealed that it has 5,502bp. Screening of random mutagenesis libraries was based on the colour development resulting from the glycosidic hydrolysis of chromogenic substrate to identify any glycosidic activity towards particular glycosyl hydrolase on LB plates or M9 plates. We have screened random mutagenesis libraries for any possible activity for β-glucosidase, β-xylosidase or for an improved β-galactosidase activity. Colonies that showed colour development on substrate even after retransformation of plasmid DNA for β-xylosidase activity were selected and its mutated plasmid DNA was sequenced. Two of the variants in which one has mutation at K552E position and another at N959Y were isolated, from two different clear blue colonies on β-xylosidase substrate. However, to the issue of change in substrate specificity (colour development on plates) was not clear. The direct evolution method applied here is seems simpler and promising in creating random mutagenesis libraries in order to select variants with useful novel properties. URI: http://hdl.handle.net/10037/3567 File(s) in this item: 1
thesis.pdf (2.624Mb) -
Svenning, Steingrim (Master thesis; Mastergradsoppgave, 15-May-2009)[+][-]
Abstract: It is now well established that p62 and NBR1 are selectively degraded by autophagy and can act as cargo receptors or adaptors for the autophagic degradation of ubiquitinated substrates. Research on autophagy in plants is also well under way, but the mechanism by which target substrates are sequestered for autophagic degradation has not been elucidated. The uncharacterized plant protein Q9SB64 shares several important functional properties with p62 and NBR1, which indicates that it could act as a cargo receptor for the autophagic degradation of ubiquitinated substrates in plants. Results from this study show that Q9SB64 polymerize via an N-terminal PB1 domain, binds ubiquitin through a C-terminal UBA domain and interacts with the Arabidopsis family of ATG8 proteins. Based on sequence similarity Q9SB64 can be viewed as the Arabidopsis orthologue of vertebrate NBR1 and named AtNBR1. Plants do not seem to have a p62 orthologue. However, with regard to the functional properties studied here AtNBR1 behaves more similar to mammalian p62 than to NBR1. URI: http://hdl.handle.net/10037/3484 File(s) in this item: 1
thesis.pdf (11.82Mb) -
Lægreid, Kari Jenssen (Master thesis; Mastergradsoppgave, 02-May-2011)[+][-]
Abstract: The mitogen activated protein kinases (MAPK) are a large and diverse family of protein kinases, contributing to the cells ability to respond to external stimuli by relaying messages in a well orchestrated way until they reach their final destinations. This is achieved through successive phosphorylation events. One member of this large family is mitogen activated protein kinase activated protein kinase 5 (MAPKAPK5/MK5), which is activated by the upstream atypical MAPKs extracellular signal-regulated kinases 3 and 4 (ERK3 and ERK4), and possibly also the conventional MAPK p38MAPK. MK5 has been shown to be implicated in F-actin rearrangement through phosphorylation of heat shock protein 27 (HSP27), tumor suppression through at least two different pathways and cell cycle arrest in response to energy depletion. There has been done relatively little research on this protein, and few bona fide substrates for MK5 are known, although knowledge is emerging. One possible interaction partner for MK5 is DNAJB1, which has been shown to be phosphorylated by MK5 in vitro. DNAJB1 is a member of the heat shock protein 40 (HSP40) family/DNAJ family, which is a subunit of the much larger heat shock protein superfamily. Heat shock proteins mostly function as chaperones and co-chaperones in the cell, assisting in the maintenance of protein homeostasis, by refolding or degrading misfolded proteins. Conditions of stress in the cell can lead to increased levels of misfolded proteins, which in turn are thought to initiate the increased transcription of heat shock proteins observed in stressed cells. DNAJB1 mainly serves as a co-chaperone for heat shock protein 70, and has been implicated to play a role in various types of cancer and neurodegenerative disorders. In this study we demonstrated that MK5 phosphorylates DNAJB1 in vitro, and that Tyrosine residue 6 and Serine residues 149, 151 and 171 in DNAJB1 are in vitro phosphorylation sites for MK5. Our results also indicate that other phosphorylation sites may be present. Further experiments are needed to elucidate the in vivo potential of these phosphoacceptor sites. We also found that MK5 and DNAJB1 exist in complexes. This interaction proved hard to reproduce, indicating that it might be of a transient nature, or perhaps a product of non-physiological conditions. We also showed that both proteins localize mainly to the nucleus in resting cells, when ectopically expressed, and that DNAJB1 seems to downregulate the level or the transcriptional activity of MK5 when both proteins are ectopically expressed in the cell. URI: http://hdl.handle.net/10037/3427 File(s) in this item: 1
thesis.pdf (1.677Mb)
Search Munin
Browse
-
All of Munin
-
This Collection
Help
Munin is powered by DSpace 1.6.2
The University Library of Tromsø, N-9037 Tromsø
Tel: +47 77 64 40 00, E-mail: munin@ub.uit.no