http://hdl.handle.net/1956/921 Search the Channel search http://bora.uib.no/simple-search http://hdl.handle.net/1956/2326 Title: Effects of alkylphenols (C4-C7) on the reproductive system of Atlantic cod (Gadus morhua) <br/> <br/>Authors: Meier, Sonnich <br/> <br/>Abstract: The work in this thesis is a part of a strategic work at the Institute of Marine Research, which aims to develop a variety of methods to be used in investigating potential endocrine disruption in Atlantic cod (Gadus morhua). Produced water, a by-product of offshore oil production, contains significant amounts of alkylphenols (APs). Many studies have shown that long-chain para-substituated APs cause endocrine disruption in freshwater fish, but relatively little is currently known about their long-term effects on the biology of marine fish. Here we describe the results from two experiments studing in detail the effects of some APs present in produced water on the reproductive potential of first-time spawning Atlantic cod. Groups of cod were fed pastes containing four APs (4-tert-butylphenol, 4-npentylphenol, 4-n-hexylphenol and 4-n-heptylphenol), at different concentrations for either 4 months (experiment 1) or 5 weeks (experiment 2). AP-exposed fish were compared to unexposed fish and to fish fed paste containing natural estrogen (17 β- estradiol). The results of the present study suggest that multiple mechanisms underlie the responses in the AP treated cod. The exposure to APs influences the plasma concentration of several male and female sex hormones and the egg yolk precursor protein, vitellogenin, in Atlantic cod. This study also shows that AP-exposure down to 20 μg/kg body burden interferes with the maturation of the sex organs, and that this effect is likely caused by disruption of the sex hormone system. There were also found effects of the AP treatment on the hepatic P450 systems (CYP1A and CYP3A) as well as glutathione, glutathione-related enzymes and changes in the lipid composition in liver and brain membranes. Even though the concentrations used in our experiments are higher than may be reasonably expected as the result of oil production alone, measurements of actual AP levels in the sea indicate that APs may still be a significant risk factor in the marine environment. Thu, 14 Jun 2007 22:58:59 GMT http://hdl.handle.net/1956/2138 Title: Expression of biomarkers (p53, transforming growth factor alpha, epidermal growth factor receptor, c-erbB-2/neu and the proliferative cell nuclear antigen) in oropharyngeal squamous cell carcinomas <br/> <br/>Authors: Ibrahim, Salah Osman; Lillehaug, Johan R.; Johannessen, Anne Christine; Liavaag, P. G.; Nilsen, Rune; Vasstrand, Endre N. <br/> <br/>Abstract: Using immunohistochemistry, expression of p53, transforming growth factor-alpha (TGF-α), epidermal growth factor receptor (EGFR), c-erbB-2/neu and proliferating cell nuclear antigen (PCNA) was examined in 26 fresh frozen tissue specimens of oropharyngeal squamous cell carcinomas (SCCs). p53 gene mutations were examined by polymerase chain reaction (PCR)/DNA sequencing methods in 22 carcinomas. The findings were examined for correlations with patients’ clinicopathological parameters. Expressions of p53 and PCNA were also examined in 21 formalin-fixed corresponding tissues. Of the fresh frozen tissue specimens, 77% (20/26) showed expression and 68% (15/22) showed mutations (substitutions) of the p53, with significant clustering of the mutations in exons 5 (8/22; 36%), 7 (4/22; 18%) and 8 (5/22; 23%). No mutations were found in exon 6. There was a discordance between expression of p53 protein and mutations of the gene. Parallel to expression and mutations of the p53 found in most of the specimens, expression of TGF-α, EGFR, c-erbB-2/neu and PCNA was found in 88% (22/25), 92% (23/25), 58% (14/24) and 91% (21/23) of the specimens, respectively. For the formalin-fixed tissue specimens, 62% (13/21) and 90% (19/21) expressed p53 and PCNA, respectively. Examining for correlations with patients’ clinicopathological parameters, expression of p53, TGF-α, EGFR and c-erbB-2/neu seemed to negatively correlate with the increase of the tumour grade. The present work suggests that: (1) lack of negative growth regulation due to inactivation of the p53 gene together with activation of other proto-oncogenes are necessary genetic events in the carcinogenesis of oropharyngeal SCCs; (2) in oropharyngeal SCCs, p53 gene mutations were clustered in exons 5 (codons 130–186), 7 (codons 230–248) and 8 (codons 271–282) which perhaps suggests that tobacco carcinogens probably affect the mutational hot spots of the p53 gene at codons 157, 175, 186, 248, 273 and 282; and (3) fresh frozen and formalin-fixed tissue specimens give similar results when an immunohistochemical method is applied. The importance of p53, TGF-α, EGFR, c-erbB-2/neu and PCNA as biomarkers in oropharyngeal SCCs deserves particular attention because it might offer further understanding of the development of these carcinomas. Thu, 29 Oct 1998 22:58:59 GMT http://hdl.handle.net/1956/2087 Title: Characterization of Nuclear Respiratory Factor 1 using transgenic zebrafish <br/> <br/>Authors: Kyrkjebø, Vibeke <br/> <br/>Abstract: Nuclear respiratory factor 1 (NRF1) is a transcription factor essential for the embryonic development of vertebrates. The zebrafish mutant nrf is characterized by apoptotic photoreceptor death during embryogenesis followed by late larval lethality. In zebrafish nrf1 is initially expressed throughout the CNS at a high level at days 1 and 2 and later fades to levels undetectable by in situ hybridization. This study shows that the initial phase of expression is crucial for photoreceptor maintenance, but not for their initial development, as homozygous mutant cells can form normal photoreceptors in a wild type background. By utilizing reporter expression of a marker insertion near the wild type allele of nrf1 combined with transgenic rescue, I show that a single heat shock induced pulse of nrf1 expression at any time between 24 and 54 hours post fertilization is sufficient to rescue the mutant phenotype and delay photoreceptor degeneration until larval stages. Moreover, no ectopic defects are detected after ubiquitous expression of the gene, suggesting that Nrf1 serves no detectable instructive role during embryogenesis. These results suggest that Nrf1 plays a permissive role in zebrafish photoreceptor maintenance and is crucial for the formation and survival of the outer nuclear layer, but is not strictly necessary for the initial development of individual photoreceptors. Gene expression comparison analysis identifies several up and downregulated genes in the nrf mutant, suggesting that the intraflagellar transport machinery of the photoreceptor connecting cilium might be defect. Thu, 30 Nov 2006 22:58:59 GMT http://hdl.handle.net/1956/1911 Title: Characterization of hARD2, a processed hARD1 gene duplicate, encoding a human protein N-α-acetyltransferase <br/> <br/>Authors: Arnesen, Thomas; Betts, Matthew J.; Pendino, Frédéric; Liberles, David A.; Anderson, Dave; Caro, Jaime; Kong, Xianguo; Varhaug, Jan E.; Lillehaug, Johan R. <br/> <br/>Abstract: Background: Protein acetylation is increasingly recognized as an important mechanism regulating a variety of cellular functions. Several human protein acetyltransferases have been characterized, most of them catalyzing ε-acetylation of histones and transcription factors. We recently described the human protein acetyltransferase hARD1 (human Arrest Defective 1). hARD1 interacts with NATH (N-Acetyl Transferase Human) forming a complex expressing protein N-terminal α-acetylation activity. Results: We here describe a human protein, hARD2, with 81 % sequence identity to hARD1. The gene encoding hARD2 most likely originates from a eutherian mammal specific retrotransposition event. hARD2 mRNA and protein are expressed in several human cell lines. Immunoprecipitation experiments show that hARD2 protein potentially interacts with NATH, suggesting that hARD2-NATH complexes may be responsible for protein N-α-acetylation in human cells. In NB4 cells undergoing retinoic acid mediated differentiation, the level of endogenous hARD1 and NATH protein decreases while the level of hARD2 protein is stable. Conclusion: A human protein N-α-acetyltransferase is herein described. ARD2 potentially complements the functions of ARD1, adding more flexibility and complexity to protein N-α-acetylation in human cells as compared to lower organisms which only have one ARD. Mon, 24 Apr 2006 22:58:59 GMT http://hdl.handle.net/1956/1793 Title: Application of in vitro transcribed and translated HIV-1 reverse transcriptase and integrase in protein-protein interaction studies <br/> <br/>Authors: Wergeland, Line <br/> <br/>Abstract: Replication of the human immunodeficiency virus (HIV) necessitates the two viral enzymes reverse transcriptase (RT) and integrase (IN). These two proteins are found to associate in a large nucleoprotein complex called the preintegration complex (PIC) together with viral nucleic acids and other viral and host proteins. Since the two proteins are localised together in the host cell, a direct interaction between them can exist, although it has been difficult to demonstrate such interaction. In this study, RT and IN were produced by in vitro transcription and translation and the proteins were used to study possible RT-IN interactions by ELISA. The RT and IN coding regions were amplified by PCR from a full length HIV-1 HxB2 clone and ligated in-frame into the in vitro translation vector pCITE-5b(+). The two plasmids generated, pCITE-RT and pCITE-IN were constructed and verified by sequencing and restriction enzyme analysis. A coupled in vitro transcription and translation kit based on rabbit reticulocyte lysate was utilised together with the two plasmids in order to obtain RT and IN. The proteins were produced unmarked since marked amino acids possibly could obscure an eventual interaction. Verification of the protein products was done by Western blotting having specific monoclonal antibodies. The proteins produced were not purified from the reticulocyte lysate but used directly in an ELISA-format to try to detect any interactions between RT and IN. With the ELISA-format, no interactions could be demonstrated. The signal was the same for all dilutions of the coating protein, as well as for the negative control. The most likely explanation for this is that there are some proteins in the reticulocyte lysate that interacts with both RT and IN. If in vitro translated proteins are going to be used to investigate protein-protein interactions by this ELISA method they need to be purified first. An other possibility is to cotranslate the two proteins in vitro. It is not sure that an eventual direct interaction between RT and IN can be detected by ELISA. Other components of the PIC may need to be present for a direct interaction to occur. Fri, 29 Oct 1999 22:58:59 GMT http://hdl.handle.net/1956/1792 Title: Binding of substrate and pterin cofactor analogue to human phenylalanine hydroxylase studied by NMR spectorscopy and molecular modeling <br/> <br/>Authors: Teigen, Knut Fri, 29 Oct 1999 22:58:59 GMT http://hdl.handle.net/1956/1589 Title: Trifluoperazine : Effects on polyphosphoniositide metabolism in neuroblastoma cells on glycerophospholipid monolayers <br/> <br/>Authors: Ølmheim, Anne Berit Tue, 29 Oct 2002 22:58:59 GMT http://hdl.handle.net/1956/1588 Title: Functional studies of two wild type variants of HIV-1 Tat <br/> <br/>Authors: Henriksen, Håvard Nyhagen Tue, 29 Oct 2002 22:58:59 GMT