Este trabalho descreve a produção dos FGFs básico bovino e ácido humano (há) em E. coli utilizando o vetor pET. Para expressar o haFGF utilizamos o cDNA nativo com pequenas modificações, obtendo cerca de 40 mg da proteína por litro de cultura induzida. No caso do bbFGF, cerca de 60 pares de bases da extremidade 5 do cDNA nativo foram substituídos por oligonucleotídeos sintéticos contendo condons frequentemente usados em genes bacterianos altamente expressos e apresentando menor conteúdo de C+G do que a sequência nativa. Com este cDNA modificado, obteve-se cerca de 10mg 1-1 de bbFGF. Os FGFs intracelulares solúveis foram purificados a partir do extrato bacteriano por chromatografia de afinidade em Heparina-Sepharose atingindo um grau de pureza da ordem de 95%. O haFGF sozinho é ativo sobre fibroblastos 3T3 em cultura na concentração de ng ml-1; na presença de heparina, a atividade desloca-se para a faixa de pg ml-1. O bbFGF é ativo na concentração de pg ml-1 e sua atividade não é significantemente potenciada pela heparina. O sequenciamento da extremidade N-terminal e a análise de aminoácidos mostraram somente uma forma de haFGF recombinante correspondente à proteína autêntica de 154 aminoácidos. Foram encontradas duas formas de bbFGF recombinante, uma correspondente à proteína autêntica de 154 resíduos e outra contendo 153, onde os dois primeiros foram removidos. / Here we describe the use of the pET expression system to produce the 154 amino acid bovine basic (bb) and human acidic (ha) FGFs. To express haFGF we have used the native cDNA sequencewith minor modifications, obtaining about 40 mg of growth factor per liter of bacterial culture. In the case of bbFGF, about 60 base pairs form the 5-end of the native cDND were replaced with synthetic oligonucleotides containing codons frequently used in highly expressed bacterial genes and having a lower G+C content than the native sequence. By using this modified cDNA about 10 mg 1-1 of bbFGF was obtained. The intracellular, soluble FGFs were partially purified from bacterial extracts by heparin-affinity chromatography and shown to be more than 95% pure. The haFGF alone is active upon 3T3 fibroblasts in culture at the level of ng ml-1 or in the range of pg ml-1 when heparin is added to the incubation medium. The bbFGF is active in the range of pg ml-1 and its activity is not significantly potentiated by heparin. Only one form of recombinant haFGF corresponding to the authentic protein of 154 amino acids was found by N-terminal protein sequencing and amino acid analysis. Two forms of recombinant bbFGF were found, one corresponding to the authentic protein of 154 amino acids (about 75%) and another containing 153 amino acids where the first two residues were removed (about 25%>).

The synthesis of proteins bearing unnatural amino acids has the potential to enhance and elucidate many processes in biochemistry and molecular biology. There are two primary methods for site specific unnatural amino acid incorporation, both of which use the cell’s native protein translating machinery: in vitro chemical acylation of suppressor tRNAs and the use of orthogonal amino acyl tRNA synthetases. Total chemical synthesis is theoretically possible, but current methods severely limit the maximum size of the product protein. In vivo orthogonal synthetase methods suffer from the high cost of the unnatural amino acid. In this thesis I sought to address this limitation by increasing cell density, first in shake flasks and then in a bioreactor in order to increase the yield of protein per amount of unnatural amino acid used. In a parallel project, I used the in vitro chemical acylation system to incorporate several unnatural amino acids, key among them the fluorophore BODIPYFL, with the aim of producing site specifically fluorescently labeled protein for single molecule FRET studies. I demonstrated successful incorporation of these amino acids into the trial protein GFP, although incorporation was not demonstrated in the final target, FEN1. This also served to confirm the effectiveness of a new procedure developed for chemical acylation.

Doctor Scientiae / An esterase and lipase producing Burkholderia multivorans strain was isolated by culture enrichment strategies. A shotgun library of Burkholderia multivorans genomic DNA (prepared in E. coli/pUC18) was screened for lipase and esterase activities. Three positive recombinant clones, pTEND5, pHOLA6 and pRASHI4, conferring esterolytic and lipolytic phenotypes respectively, were identified. Full-length sequencing of DNA inserts was performed using subeloning and "primer-walking" strategies. Nucleotide sequence analysis revealed that the pRASH14 plasmid DNA consisted of two open reading frames (ORPI and ORP2) encoding 356 and 350 amino acids, respectively. Database searches revealed that ORPI and ORP2 were homologous to lipases and chaperones from subfamily I.2. In the pTEND5 sequence, an open reading frame consisting of 978 bp, encoding 326 amino acids, was identified. Database searches revealed that this open reading frame was homologous to family Vesterases. Nucleotide sequence analysis revealed that pHOLA6, plasmid DNA consisted of 1194 bp encoding 398 amino acids and showed homology to family VIII esterases. The primary structures of LipA, EstEFH5 and EstBL from pRASHI4, pTEND5 and pHOLA6, respectively, showed a classical GxSxG motif, which is conserved in many serine hydrolases. In addition, EstBL also showed a consensus SxxK motif, the serine of which acts as a catalytic nucleophile in class C B-lactames and some peptidases.

Diabetes mellitus type I is severe autoimmune disease which is caused by destruction of insulin-producing β-cells in pancreas. Diabetic patients are dependent on external usage of insulin during their whole life. Nowadays the only treatment of diabetes type I is transplantation of entire pancreas or isolated Langerhans islets. Due to the fact that this kind of treatment is very demanding and limited availability of suitable donors, the researchers are intensively working on development of new alternative ways how to produce the insulin-producing cells. One of the possible approaches on producing insulin-positive cells is transdifferentiation of pancreatic exocrine cells via transcription factors. In this diploma thesis, the transdifferentiation of exocrine cells AR42J was carried out with in vitro synthesized mRNA encoding transcription factors Pdx1, Ngn3 and MafA. The primary mRNA structure was optimized in order to prepare highly stable mRNA which is correctly translated into the protein. The main stabilizing elements in mRNA structure include 3' and 5' untranslated region derived from highly stable β-globin mRNA. In order to verify the function of synthetic mRNA the immunofluorescence staining of transcription factors has been investigated. Synthetic mRNAs encoding transcription factors Pdx1,...

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Insect-derived baculoviruses have been used extensively as a safe and versatile research model for transgenic protein expression. Preclinical studies have revealed the promising potential of Baculoviruses as a delivery vector for a variety of therapeutic applications, including vaccination, tissue engineering and cancer treatments. Coronaviruses are enveloped viruses containing linear, non-segmented ribonucleic acid. Human coronavirus NL63 was first discovered in the Netherlands in January 2004, where a 7-month-old girl presented with an acute respiratory tract infection that was later established to predominantly infect infants, the elderly and immunocompromised individuals.

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Malaria is a fatal tropical disease affecting billions of people in impoverished countries world-wide. An alarming fact is that a child in Africa dies of malaria every 30 seconds that amounts to 2500 children per day (www.who.int/features/factfiles). Malaria is caused by the intraerythrocytic forms of Plasmodium species, notably P. falciparum, P. vivax, P. ovale and P. malariae (Hyde 2007). The spread of drug-resistant strains, failure of vector control programs, rapid growth rate of the parasite, and lack of a vaccine have further exacerbated the effects of malaria on economic development and human health. It is therefore imperative that novel drug targets are developed or current antimalarial drugs optimized (Foley and Tilley 1998). One such target is folate biosynthesis, given that folates and their derivatives are required for the survival of organisms (Muller et al. 2009). DHFR and DHPS are currently the only folate targets exploited however, their antifolate drugs are almost useless against parasite resistant strains. As such, guanosine-5’triphosphate cyclohydrolase I (GTPCHl) among other antifolate candidates are considered for intervention (Lee et al. 2001). Knock-out studies (of P. falciparum gtpchI) resulted in the suppression of DHPS activity (Nzila et al. 2005). Additionally, gtpchI amplified 11-fold in P. falciparum strains resistant to antifolates due to mutations in dhps and dhfr and this may be a mechanism for the compensation of reduced flux of folate intermediates (Kidgell et al. 2006; Nair et al. 2008). Over-expression of P. falciparum proteins in E. coli remains a challenge mainly due to the A+T rich Plasmodium genome resulting in a codon bias. This results in the expression of recombinant proteins as insoluble proteins sequestered in inclusion bodies (Carrio and Villaverde 2002; Mehlin et al. 2006; Birkholtz et al. 2008a). Comparative expression studies were conducted of native GTPCHI (nGTPCHI), codon optimized GTPCHI (oGTPCHI) and codon harmonized (hGTPCHI) in various E. coli cell lines, using alternative media compositions and co-expression with Pfhsp70. The nGTPCHI protein did not express because the gene consisted of codons rarely used by E. coli (codon bias). The expression levels of purified hGTPCHI were a greater in comparison to oGTPCHI using the different expression conditions. This is because codon-harmonization involves substituting codons to replicate the codon frequency preference of the target gene in P. falciparum, as such the translation machinery matches that of Plasmodium (Angov et al. 2008). Furthermore, greater expression levels of GTPCHI were achieved in the absence of Pfhsp70 due to expression of a possible Nterminal deletion product or E. coli protein. Purification conditions could be improved to obtain homogenous GTPCHI and further analysis (mass spectrometry and enzyme activity assays) would be required to determine the nature of soluble GTPCHI obtained. To improve the expression of soluble proteins the wheat germ expression system was used as an alternate host. However, GTPCHI expression was not effective, possibly due to degradation of mRNA template or the absence of translation enhancer elements. / Dissertation (MSc)--University of Pretoria, 2010. / Biochemistry / unrestricted

Cells that cover the body’s inner and outer surfaces are called epithelial cells. Endothelial cells are specialised epithelial cells which, among other things, line the inside of blood vessels. The endothelium is anchored to the basement membrane through molecules called laminins. In an acute inflammation laminins can bind to leukocytes so that they can reach the inflamed tissue. Chemokines are molecules that attract leukocytes and can be synthesized by endothelial cells. This report will investigate what impact stimulation with laminin-332 on endothelial cells has on their gene expression for the chemokines CCL7, CCL8, CCL20, CXCL6 and CXCL10. A previously performed analysis for protein expression which had been performed under the same conditions revealed an upregulation of all chemokines except for CCL8, which was downregulated. The analysis for protein expression was executed with Olink’s Proximity Extension Assay and analysis of gene expression was carried out with qRT-PCR. The results revealed that gene expression for CCL8, CXCL6 and CXCL10 was under the detection limit for the chosen method. Gene expression for CCL7 and CCL20 was detectable and revealed an upregulation of gene expression for both genes, which was consistent with the results from the study that analysed protein expression. This led to the conclusion that stimulus with laminin-332 upregulates mRNA expression, protein production and protein secretion in human umbilical vein endothelial cells for chemokines CCL7 and CCL20. Lastly, the involvement of the chemokines CCL7 and CCL20 in inflammation and cancer diseases is explored as well as their potential role as a biomarker for clinical treatment. / Celler som täcker kroppens inre och yttre ytor kallas för epitelceller. Endotelceller är specialiserade epitelceller som bland annat bekläder insidan av blodkärlen. Endotelet är förankrat till basalmembranet via molekyler kallade lamininer. Vid en akut inflammation kan lamininer binda till leukocyter för att de ska kunna ta sig ut till den inflammerade vävnaden. Kemokiner är molekyler som attraherar leukocyter och som kan produceras av endotelcellerna. I denna rapport utforskas vilken påverkan som laminin-332 har på endotelcellers genuttryck för kemokinerna CCL7, CCL8, CCL20, CXCL6 och CXCL10. En tidigare utförd analys för proteinuttryck som gjorts under samma förhållanden visade en uppreglering av samtliga kemokiner, med undantag för CCL8 som blev nedreglerad. Analysen för proteinuttryck var utförd med Olinks Proximity Extension Assay och analys för genuttryck utfördes med qRT-PCR. Resultaten visade att genuttrycket för CCL8, CXCL6 och CXCL10 var för lågt för att detekteras med den valda metoden. Genuttryck för CCL7 och CCL20 var detekterbart och visade båda en uppreglering av genuttryck vilket överensstämde med resultatet från studien som analyserat proteinuttrycket. Detta ledde till slutsatsen att stimulans med laminin-332 uppreglerar uttryck av mRNA, proteinproduktion och proteinsekretion i humana venösa endotelceller från navelsträng för kemokinerna CCL7 och CCL20. Slutligen, utforskas involveringen av kemokinerna CCL7 och CCL20 vid inflammation och cancerassocierade sjukdomar samt vilken roll de kan spela som biomarkörer vid behandling.

The Human Protein Atlas is an open-source database containing information about protein expression and location in the human cells,tissues and organs. The aim is to map all the proteins in humans using various biotechnology techniques such as antibody-based imaging, andRNA sequencing etc. Based on previous transcriptome analysis, 173 genes were shown to have an elevated expression in ovary compared to all other major tissue types in the human body. There is however no information regarding the expression in ovary during the reproductive years versus the post-menopausal years. In this thesis, the gene expression in ovaries of women in reproductive age was compared with women in post-menopausal age. 509 genes were found to have an at least 2-fold higher mean value RNA expression in the reproductive age group. 14 of these genes were analyzed further with antibody staining and multiplex immunofluorescence staining to localize the corresponding proteins. The results show that these genes are expressed in a variety of structures in the ovarian tissue, such as the oocyte, the granulosa cells and the corpus luteum. This thesis has demonstrated how data analysis can be used to find genes important for the ovary of women in reproductive age and in the future, this could aid research in female fertility.

The chairperson of the candidate's dissertation committee is responsible for securing the signature of each committee member and the grade, which she/he wishes to assign, to be entered in the appropriate spaces below. Most dissertations are graded on a pass (P) or no credit (NC) basis. The grades assigned need not be the same for all committee members. The exact title of the dissertation must appear in the space indicated for that purpose. The undersigned confirm that we have reviewed this document and examined the student regarding its content. We agree that this document conforms to acceptable standards of scholarly presentation in scope and quality and that the attainments of this student are such that we recommend the conferral of