Duplications and changes made on code segments by developers form code clones. Cloned code segments are exactly the same or have a particular similarity. A set of cloned code segments that have the same similarity with each other become a clone group. A clone genealogy contains several clone groups in different revisions and time periods. Based on different textual similarities, there are three clone types, i.e., Type-1, Type-2, and Type-3. Clone mutation contains the changes of clone types in the clone evolutions. Clone migration is known as moving cloned code segment to another location in the software system. In this thesis, we build clone genealogies by clone groups in two empirical studies. We conduct two studies on clone migration and clone mutation in clone genealogies. We use three large open source software systems in both studies. In the first study, we investigate if the fault-proneness of clone genealogies is affected by different patterns of clone mutation and different evolution patterns of distances among clones in clone groups. We conclude that clone groups mutated between Type-1 and Type-2 and between Type-1 and Type-3 clones have higher risk for faults. We find that modifying the location of a clone increases its risk for faults. In the second study, we study if the fault-proneness of migrated clones is affected by clone mutation with different changes on clone types. We examine if the length of time interval between clone migration and the last change of the cloned code has an impact on the faultiness of migrated clones. Our results show that the clone migration associated with clone mutation is more fault-prone than the clone migration without clone mutation. We find that a longer time interval between clone migration and the last change makes the migrated clones more fault-prone. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2013-09-01 22:10:47.925

Inherited retinal and corneal dystrophies represent a group of disorders with great genetic heterogeneity. Over 250 genes are associated with retinal diseases and 16 genes are causative of corneal dystrophies. This thesis is focused on finding the genetic causes of corneal dystrophy, Leber congenital amaurosis (LCA), Stargardt disease and retinitis pigmentosa in families from northern Sweden.  By whole exome sequencing a novel mutation, c.2816C>T, p.Thr939Ile, in Collagen Type XVII, Alpha 1 chain, COL17A1, gene was identified in several families with epithelial recurrent erosion dystrophy (ERED). We showed that the COL17A1 protein is expressed in the basement membrane of the cornea, explaining the mutation involvement in the corneal symptoms. We could link all the families in this study to a couple born in the late 1700s confirming a founder mutation in northern Sweden. Our finding highlights role of COL17A1 in ERED and suggests screening of this gene in patients with similar phenotype worldwide. Furthermore the genetic causes in several retinal degenerations were identified. In one family with two recessive disorders, LCA and Stargardt disease, a novel stop mutation, c.2557C>T, p.Gln853Stop, was detected in all LCA patients. In the Stargardt patients two intronic variants, the novel c.4773+3A>G and c.5461-10T>C, were detected in the ABCA4 gene. One individual was homozygous for the known variant c.5461-10T>C and the other one was compound heterozygote with both variants present. Both variants, c.4773+3A>G and c.5461-10T>C caused exon skipping in HEK293T cells demonstrated by in vitro splice assay, proving their pathogenicity in Stargardt disease. Finally, in recessive retinitis pigmentosa, Bothnia Dystrophy (BD), we identified a second mutation in the RLBP1 gene, c.677T>A, p.Met226Lys. Thus, BD is caused not only by common c.700C>T variant but also by homozygosity of c.677T>A or compound heterozygosity. Notably, known variant, c.40C>T, p.R14W in the CAIV gene associated with a dominant retinal dystrophy RP17 was detected in one of the compound BD heterozygote and his unaffected mother. This variant appears to be a benign variant in the population of northern Sweden. In conclusion, novel genetic causes of retinal dystrophies in northern Sweden were found demonstrating the heterogeneity and complexity of retinal diseases. Identification of the genetic defect in COL17A1 in the corneal dystrophy contributes to understanding ERED pathogenesis and encourages refinement of IC3D classification. Our results provide valuable information for future molecular testing and genetic counselling of the families.

Ovarian cancer accounts for more deaths than all other gynaecological cancers taken together. The 5 year survival rate can be as high as 80% for cases diagnosed early, but the asymptomatic nature of the disease means that it is most frequently detected in the later stages. By this time, disease has invariably spread beyond the ovaries and the survival rate drops to around 30%. Treatment of ovarian cancer often fails due to a high rate of chemoresistance and novel methods of treatment and detection are required to increase the survival chances of patients. This study sought to determine whether gene therapy for sporadic ovarian cancer could offer a novel and more successful treatment option for the disease. Mutation or abnormal expression of the p53 gene has already been shown to be the most common genetic even in ovarian cancer, being involved in up to 70% of cases. Wild-type p53 was delivered, using liposomes, into p53 mutant ovarian cancer cell lines and this resulted in a restoration of the wild-type functions of the gene, namely cell cycle arrest and apoptosis. The results from the cell line studies suggested that restoration of the wild-type p53 function limit or reduce tumour progression and increase the sensitivity of the tumour to chemotherapy. A mouse model of human peritoneal ovarian cancer was then constructed and the wild-type p53 gene was administered in liposomes into the peritoneum. The results suggested that p53 gene therapy prevents tumours from growing in the mice, when compared to a control gene. It is now known that p53 gene therapy for humans is being clinically assessed. There are a proportion of tumours that do not harbour an abnormal p53 gene, raising the possibility that other tumour suppressor gene mutations may play a role in the molecular genetic control of growth arrest and apoptosis. P53-dependent, apoptosis-regulating family members bcl-2 and bax were analysed immunohistochemically to determine their involvement in ovarian cancer. Both proteins were significantly associated with malignancy and also with overall length of survival, but not associated with the various prognostic factors such as stage and differentiation of tumour. It is unlikely that these genes will become targets for gene therapy in ovarian cancer. Mutation, deletion and hypermethylation of the p53-independent pi6 gene, alter its function, resulting in loss of G1 cell cycle arrest control. The status of methylation of the pi 6 promoter in ovarian tumours was determined and combined with mutation data, resulting in the conclusion that abnormal pi 6 was not a common event in ovarian cancer and is therefore not a likely candidate for gene therapy. This study has contributed to the evergrowing wealth of knowledge on the molecular genetic events of ovarian cancer, and has shown that gene therapy for sporadic ovarian cancer as a clinical application is feasible.

Zur SLC22-Genfamilie von Karnitin- und organischen Ionentransportern gehören u. a. auch die organischen Kationentransporter der Ratte rOCT1 und rOCT2 sowie deren humane Analoga. Diese funtionell bereits gut charakterisierten Proteine werden in verschiedenen Geweben exprimiert und transportieren endogene und pharmakologisch relevante Substanzen. Die Aufklärung des Transportmechanismus und der Regulation sind Gegenstand intensiver Forschungsbemühungen. In dieser Arbeit wurde durch elekrophysiologische Methoden, die modifiziert auch zur Messung von Membrankapazitäten und des Strom-Teilchen-Aufnahmeverhältnisses (CFR) eingesetzt wurden, der Effekt des ungeladenen, membranpermeablen SH-Gruppenregenz MMTS auf den in Xenopus laevis-Oozyten exprimierten rOCT1 untersucht. Durch MMTS kam es zu einer Aktivierung von substratinduzierten Strömen und Kapazitätsänderungen, einer unterschiedlichen Veränderung von Substrat- und Inhibitoraffinitäten sowie einer Zunahme der absoluten Oozytenmembrankapazität. Die CFR und die Spannungsabhängigkeit änderten sich nicht. An rOCT2 konnten teils gleich-, teils gegensinnige Veränderungen nach MMTS-Exposition gezeigt werden. Diese Phänomene können am ehesten durch eine Konformationsänderung der polyvalenten Substratbindungsregion, einen verstärken Membraneinbau der Transportermoleküle und eine gesteigerte Transportrate des Einzeltransporters erklärt werden. Durch die Untersuchung von Mutanten konnten die Cysteine 322 und 451 als essentiell für den MMTS-Effekt identifiziert werden. Die Daten deuten darauf hin, dass die Modifikation dieser Cysteine für die Effekte zwingend erforderlich ist. Möglicherweise ist aber ein Xenopus-eigenes Regulatorprotein an der Entstehung der Effekte beteiligt, welches in die entsprechenden Proteinregionen des rOCT1 eingreift. Mit der Identifikation von Cystein 451 konnte ein weiterer Beweis für die wichtige Bedeutung der 10. Transmembrandomäne erbracht werden. Mit dem Cystein 322 wurde eine weitere wichtige Aminosäure für die Funktion und möglicherweise auch die Regulation von rOCT1 identifiziert. / rOCT1 and rOCT2 are functionally well characterised members of the SLC22-transporter family. It includes carnitine and organic cation and anion transporters. OCTs are expressed in a variety of tissues and transport a number of drugs and endogenous substrates. Their transport mechanism and regulation are currently intensively being investigated. MMTS is an uncharged and membrane-permeable SH-reactive substance. Using electrophysiological methods the effect of MMTS on rOCT1 expressed in X. laevis-oocytes was investigated. These methods were modified to measure membrane capacitance and current-flux-ratios. MMTS-exposure induced an activation of substrate-induced currents and capacitance changes, a differing alteration of substrate and inhibitor affinities and an increase in the absolute oocyte membrane capacitance. The transport stoechiometry and voltage dependence were not influenced by MMTS exposure. Properties of rOCT2 were partially altered in the same and partially in the opposite way. The effects can most likely be explained by a conformational change of the polyvalent substrate binding region, an increased membrane insertion of OCT molecules and an increased substrate turnover number of the single transporter. Investigating mutants the cysteines 322 and 451 could be identified to be essential for the MMTS-effect. The data suggest that the modification of both cysteines is absolutely necessary to create the seen effects. However the participation of a Xenopus regulatory protein for the induction of the MMTS-effect interfering with the mentioned OCT regions must be taken into account. The identification of cysteine 451 proves once more the importance of the 10th TMD within the OCT family. Cyteins 322 might be another important amino acid for functional properties and the regulation of organic cation transporters.

Ziel dieser Arbeit war es, NF-AT1-Gen-defiziente Mauslinien zu erzeugen und die Folgen dieser genetischen Manipulation in vivo zu untersuchen. Die Untersuchung sollte die durch die Gendefizienz erwarteten Mängel während der Entwicklung (Embryogenese) und, im Besonderen, die Auswirkungen auf das Immunsytem und die Entwicklung und Differenzierung der T-Zellen aufzeigen. Zur Untersuchung der genomischen Organisation des Maus-NF-AT1-Gens wurde eine genomische l-Phagen-DNA-Bibliothek "gescreent" (durchgeführt von Dr. E. Jankevics, Universität von Riga, Lettland), die entsprechenden l-Phagen, die das NF-AT1-Gen enthielten, isoliert und die DNA präpariert. Nach Analyse der klonierten Phagen (Subklonierung und Sequenzierung) wurde eine Restriktionskarte der entsprechenden Bereiche erstellt und der "targeting-vector" erstellt. Der "targeting-vector" wurde durch Elektroporation in embryonale Stammzellen (ES-Zellen) eingebracht und die Integration in das Genom ("Homologe Rekombination") durch Southern Blotting- bzw. PCR-Analyse untersucht. Manipulierte ES-Zellklone wurden in C57Bl/6-Blastozysten injiziert, diese in scheinschwangere Ammentiere transferiert und die Nachkommen nach Geburt anhand der Fellfarben klassifiziert. Nachkommen mit einem hohen Anteil hellen Fells wurden mit C57 Bl/6-Tieren verpaart und die Integration des manipulierten Zellklons in die Keimbahn wurde anhand der wildtypischen Fellfarbe und Genotypisierung nachgewiesen. Bezüglich des manipulierten NF-ATp-Gens heterozygote F1-Tiere wurden miteinander verpaart, um eine homozygote NF-ATp-defiziente Mäuse zu erhalten. Die Deletion des NF-ATp-Proteins wurde durch in Western-Blotting-Experimenten und EMSAs ("electrophoretic mobility shift assays") nachgewiesen. Die NF-ATp-/--Tiere zeigten keine augenscheinlichen Veränderungen während der Entwicklung und, bei jungen Tieren, keine offensichtlichen Veränderungen bei der Entwicklung des Immunsystems. In älteren Tieren (> 6 Wochen) war eine Hyperproliferation der Zellen des Immunsystems zu beobachten, was mit einer Splenomegalie, einer verstärkten Bildung von Keimzentren in lymphatischen Organen, vergrößerten Lymphknoten und einer verlangsamten Involution des Thymus einherging. Weitergehende Untersuchungen der Ursache dieser hyperproliferativen Erkrankung offenbarten eine verminderte klonale Deletion nach Aktivierung. Die Ursachen dieses überraschenden Effekts sind wahrscheinlich vielfältig, da NF-AT-Faktoren an der Regulation der Expression vieler Gene beteiligt sind, u.a. des Apoptose-assoziierten CD95-Liganden. Da sich bezüglich der IL-2-Expression keine Unterschiede zwischen NF-ATp-defizienten Tieren und Kontrollen zeigten, jedoch eine erhöhte IL-2-Konzentration im Medium kultivierter NF-ATp-defizienter T-Zellen beobachtet wurde, wurde die Bindung von NF-ATp an putative NF-AT-Bindungssequenzen des CD25-Promotors, die transkriptionelle Aktivierung des Promotors mittels Luciferase-Assays und die Expression der IL-2R-alpha-Kette (CD25) untersucht. Es konnte gezeigt werden, daß (1.) NF-ATp an zwei Regionen des CD25-Promotors bindet, (2.) der CD25-Promotor durch NF-ATp transkriptionell stark stimuliert wird und (3.) T-Zellen NF-ATp-defizienter Tiere nach Stimulation eine verminderte CD25-Expression zeigen. In NF-ATp-defizienten Tieren war die Expression von CD25 moderat reduziert, was eine Erklärung für den abgeschwächten Phänotyp dieser Tiere - im Vergleich zu IL-2- oder CD25-defizienten Tieren - sein kann. Die hyperproliferativen Erkrankungen dieser verschiedenen Mauslinien weisen auf eine Beteiligung der NF-AT-/IL-2-/IL-2R-Signalwege nicht nur während der T-Zell-Aktivierung hin, sondern auch auf eine Beteiligung an Signalwegen, die zur anschließenden Inaktivierung und Apoptose der T-Lymphozyten nötig sind. / Aim of this work was the generation of NF-ATp-deficient mice and to investigate the effects of this genetic manipulation in vivo. The investigation included observation of defects during embryogenesis and, in particular, effects on development and differentiation of T cells of the immune system. To characterize the genomic organisation of the NF-ATp gene, a genomic DNA library was screened (done by E. Jankevics, PhD, University of Riga, Latvia), the NF-ATp gene containing phages isolated and analyzed (subcloning and sequencing). A restriction map was made, necessary for construction of the targeting vector. The targeting vector was brought into E14.1 embryonic stem cells by electroporation and integration through "homologous recombination" was confirmed by Southern blotting and PCR analysis. Successfully manipulated ES cell clones were injected in C57 Bl/6 blastocystes, injected blastocystes transferred into pseudo-pregnant foster mice, and the offsprings classified according to coat colour. Offsprings showing a high level of fair coat colour were mated to C57Bl/6 inbreed animals, integration of the manipulated cell clone into germline was verified by wild-type coat colour and genotyping. Heterozygous animals were crossbred to obtain homozygous NF-ATp-deficient animals. Loss of NF-ATp protein was confirmed in Western blotting assays and EMSAs. NF-ATp-deficient mice showed no obvious changes in embryogenesis and no differences in the development of the immune system. Older Animals (> 6 weeks) developed a hyperproliverative disorder of lymphatic cells going along with splenomegalie, enlarged lymph nodes and retarted involution of the thymus. Further investigations revealed a normal activation but reduced clonal deletion of T cells after activation. This may be due to different causes, since NF-AT factors are involved in the regulation of many genes, e.g. the apoptosis-associated CD95 ligand. Phenotypical similarities with interleukin 2- (IL-2) or IL-2 receptor- (IL-2R) deficient mice and, in contrast, the observation of elevated IL-2 levels in supernatants of cultivated NF-ATp-deficient T cells, suggested a role of NF-ATp in the regulation of the IL-2/IL-2R system. Since no difference in IL-2 expression between NF-ATp-/--mice and controls was observed, binding of NF-ATp to putative NF-AT concensus sequences of the CD25 (IL-2R alpha chain) promoter, transcriptional activation by NF-ATp, and expression of CD25 were investigated. It was demonstrated that (1) NF-ATp binds to two regions of the CD25 promoter, (2) that NF-ATp is a stimulator of the CD25 promoter, and (3) T cells of NF-ATp-deficient mice display a decreased expression of CD25 after stimulation, compared to wild-type controls. The expression of CD25 is moderately decreased in NF-ATp-deficient mice, proposing an explanation for the "weak phenotype" of NF-ATp-/--mice, compared to IL-2- or IL2R-deficient mice. The hyperprolifertive disorders of these different mouse lines are pointing towards a participation of NF-AT-/IL-2-/IL-2R signaling not only in activation of T cells, but also in pathways necessary for subsequent inactivation.

Masernvirus (MV) ist ein negativ-strängiges RNA-Virus, das im Menschen und im Nagermodell zu akuten und subakuten Enzephalitiden führen kann. Es wurde beschrieben, dass bestimmte Antikörperescape-Mutanten des MV neurovirulent, andere nicht neurovirulent sind (Liebert et al., 1994). Mit Hilfe von rekombinanten Masernviren, konnte ich diejenigen Aminosäuren charakterisieren, die einerseits für die Bindung monoklonaler, neutralisierender anti-MV-H-Antikörper (K29, K71, Nc32 und L77) und andererseits für die Neurovirulenz verantwortlich sind. Bei den rekombinanten MV wurde das von Duprex et al. (1999) als Neurovirulenz vermittelnd beschriebene H-Gen des nagerhirnadaptierten neurovirulenten CAM/RB-Stammes in das Grundgerüst des nicht neurovirulenten Edtag (molekularer Klon des Vakzinestammes Edm) kloniert. Über gerichtete Mutagenese wurden die jeweiligen Mutationen in dieses CAM/RB H-Gen eingefügt. Mittels der FACS-Analyse konnten die Aminosäureänderungen identifiziert werden, die für die Bindung der jeweiligen Antikörper verantwortlich sind. Sie befinden sich nach einem Strukturmodell der H-Proteine (Langedijk et al., 1997) im Membran-distalen Teil, den so genannten Propellern. Im Einzelnen sind folgende Aminosäureänderungen im Hämagglutinin-Protein für den Escape verantwortlich: L77 – 377 Arg -> Gln und 378 Met -> Lys; Nc32 – 388 Gly -> Ser; K71 – 492 Glu -> Lys und 550 Ser -> Pro; K29 – 535 Glu -> Gly. Es konnte ferner gezeigt werden, dass die beiden Aminosäureveränderungen an den Positionen 195 und 200 gemeinsam für die Neurovirulenz verantwortlich sind und nicht assoziiert sind mit den Mutationen für den Antikörperescape. Der Aminosäureaustausch an Position 200 bei neurovirulenten Viren führt zum Verlust einer benutzten Glykosylierungsstelle. Diese Mutation ist jedoch nicht alleine für das unterschiedliche Neurovirulenzverhalten der Viren verantwortlich, sondern es muss gleichzeitig der Austausch an Position 195 vorhanden sein, der eine positive Ladung im H-Molekül entfernt. Diese beiden Mutationen sind nach dem Strukturmodell nach Langedijk im Stamm2-Bereich angesiedelt. Sind im H-Protein an Stelle 195 und 200 die Aminosäuren Gly und Ser vorhanden, so findet im Gehirn neugeborener Lewis-Ratten eine verstärkte Virusvermehrung und Ausbreitung statt, die die akute Enzephalitis mit Expression typischer proinflammatorischer Zytokine zur Folge hat. Werden an Stelle 195 und 200 die Aminosäuren Arg und Asn exprimiert, so ist der Verlauf der Infektion inapparent. In dieser Arbeit wurde auch ein Zellkultursystem gemischter Hirnzellen neugeborener Lewis-Ratten etabliert, das die Unterschiede der Virusausbreitung in vivo reflektiert und mit dem weitere Untersuchungen zum Mechanismus der Neurovirulenz durchgeführt werden könnten. Anhand der durchgeführten Untersuchungen mit Ratten des CD46 transgenen Lewis-Modells konnte gezeigt werden, dass die Anwesenheit des Rezeptors CD46 das Virulenzverhalten der getesteten Viren nicht beeinflusst. Weder mit dem Vakzinestamm Edm noch mit einem nicht an Nager adaptierten Wildtypstamm, konnte nach intracerebraler Injektion eine akute Enzephalitis induziert werden. Die Untersuchungen zeigen, dass die Neurovirulenz des an Nager-adaptierte MV-Stammes CAM/RB essentiell von den Aminosäuren Gly und Ser an Position 195 und 200 im H-Protein abhängt und nicht durch die transgene Expression zellulärer Rezeptoren für MV vermittelt werden kann. / Measles virus (MV) is a negative stranded RNA-virus, which may lead to acute and subacute encephalitis in men and experimentally also in rodents. It has been described that certain antibody escape mutants of MV are neurovirulent, whereas others are non-virulent (Liebert et al., 1994). Here I determined with the help of recombinant MV the amino acids which are responsible for the binding of neutralizing monoclonal anti MV-H-antibodies (K29, K71, Nc32 and L77) or for neurovirulence of MV. The H-gene of the rodent brain adapted strain CAM/RB which was described for determining neurovirulence by Duprex et al. (1999) was introduced into the non-neurovirulent backbone of Edtag, which is the molecular clone of the vaccine strain Edm. The respective mutations were introduced by site directed mutagenesis. In FACS-analysis I could determine the amino acid changes which are responsible for the binding of the anti H-antibodies. In a structural model for MV-H (Langedijk et al., 1997) this amino acids reside in the membrane distal part of the molecule - the so called propeller. The following amino acid changes in the hemagglutinin protein are responsible for the antibody escape: L77 – 377 Arg -> Gln und 378 Met -> Lys; Nc32 – 388 Gly -> Ser; K71 – 492 Glu -> Lys und 550 Ser -> Pro; K29 – 535 Glu -> Gly. In addition I found that the combined amino acid changes at positions 195 and 200 are responsible for neurovirulence but are not associated with the antibody escape. The amino acid change at position 200 leads to the loss of a used glycosylation site in neurovirulent strains. The mutation at position 200 is not alone responsible for the neurovirulence but requires the second associated mutation at position 195, which deletes an additional positive charge in the H-protein. These two mutations which are responsible for the neurovirulence reside in the stem2 region of the structural model according to Langedijk. If in the H-protein the amino acids at position 195 and 200 are Gly and Ser, the virus multiplication and spread is enhanced in the brain of newborn Lewis-rats and causes an acute encephalitis with expression of typical proinflammatory cytokines. If at position 195 and 200 the amino acids Arg and Asn are present, the infection stays inapparent. I could also establish a cell culture system of mixed primary rat brain cells, which reflects the difference in the viral spread in vivo and which may be to used further to investigate the mechanisms responsible for neurovirulence. Results obtained with CD46 transgenic Lewis-rats showed that the presence of the MV receptor CD46 does not influence the virulence of the tested strains. Neither the vaccine strain nor a wildtype strain not adapted to rodents could induce acute encephalitis after intracerebral injection. These findings suggest that the neurovirulence of the rodent-brain adapted MV-strain CAM/RB depends essentially on amino acids Gly and Ser at positions 195 and 200 in the H-protein, and cannot be mediated by the transgenic expression of cellular receptors for MV.

Geok-yen Yeo. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 225-233). / Title page --- p.i / Members of Thesis Advisory Committee --- p.ii / Abstract --- p.iii -iv / Acknowledgments --- p.v / Dedication --- p.vi / Table of Contents --- p.vii -xi / Chapter CHAPTER 1 --- INTRODUCTION --- p.1-31 / Chapter 1.1 --- General Introduction --- p.1 / Chapter 1.2 --- Fermentation --- p.1 / Chapter 1.3 --- Growth in Escherichia coli --- p.3 / Chapter 1.3.1 --- Aerobic growth in Escherichia coli --- p.3 / Chapter 1.3.2 --- The regulation of enzyme synthesis during cell metabolism --- p.7 / Chapter 1.3.3 --- Anaerobic growth in E. coli --- p.8 / Chapter 1.3.4 --- Anaerobic regulation by the transcriptional regulator Fnr --- p.12 / Chapter 1.3.5 --- "The case for ""Pasteur Control Proteins"" (PCP)" --- p.13 / Chapter 1.4 --- The family of alcohol dehydrogenases : An overview --- p.15 / Chapter 1.4.1 --- Molecular characteristics of alcohol dehydrogenases --- p.17 / Chapter 1.4.2 --- Residue conservation in alcohol dehydrogenases --- p.24 / Chapter 1.4.3 --- The effect of amino acid substitution on substrate specificity --- p.25 / Chapter 1.5 --- Alcohol dehydrogenases in bacteria --- p.28 / Chapter 1.5.1 --- Alcohol dehydrogenase in E. coli --- p.28 / Chapter 1.6 --- Aims of this study --- p.30 / Chapter CHAPTER 2 --- MATERIALS & METHODS --- p.32 -90 / Chapter 2.1 --- Bacterial strains --- p.32 / Chapter 2.2 --- Plasmids --- p.32 / Chapter 2.2.1 --- "Low copy number plasmid, pTJS75Km" --- p.32 / Chapter 2.2.2 --- "High copy number plasmid, pUC18" --- p.33 / Chapter 2.3 --- Bacterial culture media and solutions --- p.39 / Chapter 2.3.1 --- Luria Bertani (LB) medium --- p.39 / Chapter 2.3.2 --- L-Broth + MOPS --- p.39 / Chapter 2.3.3 --- "R medium, containing Triphenyltetrazolium chloride-ethanol (TTC-EtOH)" --- p.40 / Chapter 2.3.4 --- SOB and SOC media --- p.41 / Chapter 2.3.5 --- M9 Glucose medium --- p.42 / Chapter 2.3.6 --- Terrific Broth (TB) --- p.42 / Chapter 2.3.7 --- Rich Broth (RB) --- p.43 / Chapter 2.3.8 --- Antibiotic solutions --- p.43 / Chapter 2.4 --- Restriction endonucleases and other enzymes --- p.44 / Chapter 2.5 --- Isolation of chromosomal DNA --- p.45 / Chapter 2.5.1 --- Preparation of chromosomal DNA by spooling --- p.45 / Chapter 2.5.2 --- Preparation of chromosomal DNA by cesium chloride density gradient --- p.48 / Chapter 2.6 --- Isolation of plasmid DNA --- p.50 / Chapter 2.6.1 --- Large-scale preparation of plasmid by CsCl density gradient --- p.50 / Chapter 2.6.2 --- Small-scale preparation of plasmid DNA --- p.54 / Chapter 2.6.2. --- A Boiling method --- p.54 / Chapter 2.6.2. --- B Alkaline Lysis method --- p.55 / Chapter 2.6.3 --- Preparation of plasmid DNA by Qiagen columns --- p.56 / Chapter 2.7 --- Purification of DNA --- p.59 / Chapter 2.7.1 --- Ethanol precipitation --- p.59 / Chapter 2.7.2 --- Concentration and desalting using Centricon columns --- p.59 / Chapter 2.7.3 --- Purification of DNA by Geneclean procedure --- p.61 / Chapter 2.8 --- DNA cloning techniques --- p.63 / Chapter 2.8.1 --- Restriction endonuclease digestion --- p.63 / Chapter 2.8.2 --- Agarose-ethidium bromide gel electrophoresis --- p.65 / Chapter 2.8.2. --- A Gel loading buffer --- p.66 / Chapter 2.8.2. --- B Electro-elution of DNA --- p.67 / Chapter 2.8.3 --- Size fractionation --- p.68 / Chapter 2.8.3. --- A Salt gradient fractionation --- p.68 / Chapter 2.8.3. --- B Sucrose gradient --- p.70 / Chapter 2.8.4 --- Dephosphorylation of restriction-enzyme digested vector plasmid using calf intestinal phosphatase (CIP) --- p.71 / Chapter 2.8.5 --- Ligation of vector and insert --- p.72 / Chapter 2.8.6 --- Preparation of competent cells --- p.73 / Chapter 2.8.7 --- DNA transformation --- p.75 / Chapter 2.8.7.A --- By heat shock --- p.75 / Chapter 2.8.7.B --- By electroporation --- p.75 / Chapter 2.9 --- Screening for adhC transformants --- p.78 / Chapter 2.9.1 --- Screening for adhC clones --- p.78 / Chapter 2.9.2 --- Screening for pUC18 transformants --- p.79 / Chapter 2.10 --- Confirmation of adhC clones --- p.80 / Chapter 2.10.1 --- Reproduction of red colonies on R plates and antibiotic resistance --- p.80 / Chapter 2.10.2 --- T7 phage test for E. coli strains --- p.80 / Chapter 2.10.3 --- Plasmid size determination --- p.82 / Chapter 2.10.4 --- Re-transformation into E. coli host strains --- p.82 / Chapter 2.10.5 --- Physiological study of adhC clones --- p.83 / Chapter 2.10.6 --- Alcohol dehydrogenase assay --- p.84 / Chapter 2.11 --- The dye-binding method of protein determination --- p.87 / Chapter 2.12 --- Special procedures --- p.88 / Chapter 2.12.1 --- Generation of adh clones with deletions --- p.88 / Chapter 2.12.2 --- Sequencing reactions --- p.89 / Chapter CHAPTER 3 --- RESULTS: PART I Cloning and Restriction Mapping of the adhC mutation in a low copy number plasmid vector --- p.91 -122 / Chapter 3.1 --- Introduction: Cloning strategy --- p.91 / Chapter 3.2 --- Cloning of the adh mutation from strain CC2807B (an ADH overproducing mutant strain) in pTJS75Km --- p.93 / Chapter 3.2.1 --- Construction of the 'HK' clones --- p.93 / Chapter 3.3 --- Restriction mapping of the adh clones --- p.101 / Chapter 3.4 --- Subcloning the adhC insert --- p.110 / Chapter 3.4.1 --- Construction of plasmid pHK14 --- p.110 / Chapter 3.4.2 --- Construction of plasmid pHK15 --- p.115 / Chapter 3.4.3 --- Construction of plasmid pSS22 --- p.121 / Chapter 3.5 --- Remarks concerning the clones --- p.121 / Chapter CHAPTER 4 --- RESULTS:PART II Cloning and Sequencing of the adhC mutation in a high copy number plasmid vector --- p.123 -148 / Chapter 4.1 --- Introduction --- p.123 / Chapter 4.1.1 --- Choice of sequencing strategy --- p.123 / Chapter 4.1.2 --- An attempt to eliminate clone instability --- p.124 / Chapter 4.2 --- Subcloning of adh insert in pUC18 --- p.125 / Chapter 4.2.1 --- Study of adh clone EPR --- p.125 / Chapter 4.2.2 --- Re-construction of plasmid pEPR ( = pEE5) --- p.126 / Chapter 4.2.3 --- Construction of plasmids pEH2 and pEH3 --- p.127 / Chapter 4.2.4 --- Construction of a nested deletion library --- p.138 / Chapter CHAPTER 5 --- RESULTS : PART III Sequencing of the Mutation --- p.149 -177 / Chapter 5.1 --- Nucleotide sequencing --- p.149 / Chapter 5.2 --- Sequencing of the cloned adhC gene insert --- p.150 / Chapter 5.3 --- Analysis of the sequenced DNA by DNASIS computer software --- p.151 / Chapter 5.3.1 --- Search for codons associated with initiation and termination of transcription using the open reading frame (ORF) search --- p.151 / Chapter 5.3.2 --- Translation of the nucleotide sequence at the open reading frame (start 223 - end 2896) --- p.152 / Chapter 5.4 --- Search for DNA sequence homology with known DNA sequences --- p.152 / Chapter 5.4.1 --- Sequence homology of the structural gene (nucleotide # 223- #28%) : Two nucleotide changes revealed in DNA sequence of the structural gene adhE of Escherichia coli --- p.153 / Chapter 5.4.2 --- adhC mutation is due to changes in two amino acids --- p.153 / Chapter 5.4.3 --- The DNA sequence 5' of the mutated structural gene (upstream sequence) --- p.155 / Chapter 5.4.4 --- The DNA sequence 3' of the mutated structural gene (downstream sequence) --- p.156 / Chapter 5.5 --- Comparisons between the computer-predicted properties of the mutant and wild-type protein --- p.156 / Chapter 5.5.1 --- Prediction of the alcohol dehydrogenase protein secondary structure by the Robson Method --- p.156 / Chapter 5.5.2 --- Isoelectric point prediction --- p.156 / Chapter CHAPTER 6 --- RESULTS : PART IV Comparative Studies of Alcohol Dehydrogenase Expressionin adhC Strains and Clones --- p.178 -203 / Chapter 6.1 --- Introduction --- p.178 / Chapter 6.1.1 --- Basis for the alcohol dehydrogenase assay --- p.178 / Chapter 6.1.2 --- Choice of assay method --- p.179 / Chapter 6.1.3 --- Points to consider for ADH assay --- p.179 / Chapter 6.2 --- General growth characteristics of bacterial strains --- p.181 / Chapter 6.2.1 --- Plate cultures --- p.181 / Chapter 6.2.2 --- Overnight liquid cultures --- p.183 / Chapter 6.2.3 --- Batch liquid cultures --- p.183 / Chapter 6.2.4 --- ADH activity of strain CC2807B --- p.190 / Chapter 6.2.5 --- Comparison of ADH activity --- p.192 / Chapter 6.3 --- Investigating the mutated ADH enzyme --- p.197 / Chapter 6.3.1 --- Oxygen inactivation of the mutated enzyme --- p.197 / Chapter 6.3.2 --- Thermostability of the mutated enzyme --- p.201 / Chapter CHAPTER 7 --- DISCUSSION --- p.204 -220 / Chapter 7.1 --- Cloning of the adhC mutation --- p.204 / Chapter 7.1.1 --- Instability of clones in plasmid vector pUC18 --- p.204 / Chapter 7.1.2 --- Eliminating 'toxic' genes adjacent to adh locus --- p.207 / Chapter 7.1.3 --- Cloning in pTJS75Km low copy number vector --- p.208 / Chapter 7.2 --- DNA sequence of the adhC clones --- p.211 / Chapter 7.2.1 --- The basis for sequencing pUC 18-derived clones --- p.211 / Chapter 7.2.2 --- Homology to known alcohol dehydrogenases (ADH) sequences --- p.213 / Chapter 7.3 --- Findings concerning the adhC mutation --- p.217 / Chapter 7.3.1 --- How amino acid substitutions may affect an enzyme --- p.217 / Chapter 7.3.2 --- Physiological aspects of the bacterial cell due to the mutated enzyme --- p.218 / Chapter 7.4 --- Conclusions --- p.220 / APPENDICES --- p.221 -224 / REFERENCES --- p.225 -233

Regulation of pre-mRNA splicing is a key process for most if not all eukaryotes. The process can, in the abstract, be considered as a series of trans-acting factors that interact with cis-motifs in the RNA to enable the removal of introns and joining of exons. As the cis factors need not only be the splice sites themselves, but also motifs in the exons, the splicing process has the potential to impose selective constraint on exonic sequence in addition to the normal selection on the amino acid content of the protein. To understand this more clearly, in this thesis, I mainly focus on a type of important and widely investigated cis-motifs, exonic splicing enhancers (ESEs), which bind with SR proteins to re-enforce the splice sites and so ensure splicing correctly. First, I explore splice-related cis-motif usage of the Ectocarpus genome, which is a species phylogenetically very distant from vertebrates but, like vertebrates in having abundant large introns. A deep phylogenetic conservation of exonic splice-related constraints is observed (Chapter II). Then I extend the analysis across taxa in a phylogenetically explicit framework. In this section stronger selection on exon end synonymous sites can be detected within humans when the exons are flanked by larger introns. Additionally I report evidence that reduced Ne might lead to larger introns and weakened splice sites. Thus I suggest an unusual circumstance in which selection (for cis-motifs to control error-prone splicing) might be stronger when population sizes are smaller; this is unexpected and would be a necessary complement to nearly-neutral theory (Chapter III). Third, I ask whether what we know about biases in the usage of ESEs and splicing control elements allows us to understand where in human genes pathogenic mutations tend to occur (Chapter IV). By examining the relationship between determinants of the usage of splice-associated cis-motifs and the distribution of human pathogenic SNPs, I found certain exons are vulnerable to splice disruption owing to low ESE density and a “fragile” exon model we proposed could describe and explain this phenomenon (Chapter IV). Finally I perform preliminary analysis, with a view to biotechnological optimization of transgenes, to address whether there might be such a thing as a tissue specific ESE. To this end I examine ESE usage in tissue specific genes. I find some preliminary evidence for tissue specific biased usage of certain ESEs.

The past fifteen years have seen a revolution in human population genetics. We have gone from anecdotal genetic data from a few individuals at a few genetic loci to an avalanche of genome-wide sequencing data, from many individuals in many different human populations. These new data have opened up many new directions of research in human population genetics. In this work, I explore two such directions. Genomic data have uncovered that recent changes in human population size have had dramatic effects of on the genomes of different human populations. These effects have raised the question of whether historic changes in population size have led to differences in the burden of deleterious mutations, or mutation load, between different human populations. In Chapter 1 of this thesis, I show that despite earlier arguments to the contrary only minor differences in load are expected and indeed observed between Africans and Europeans. Over the past decade, genome-wide association studies (GWAS) have begun to systematically identify the genetic variants underlying heritable variation in quantitative traits. The number, frequencies and effect sizes of these variants reflect the selection, and other evolutionary processes, acting on traits. In Chapter 2, I develop a model for traits under pleiotropic, stabilizing selection, relate the model’s predictions to GWAS findings, and show that GWAS findings for height and BMI indeed follow model predictions. In Chapter 3, I develop a method to infer the distribution of selection coefficients acting on genome-wide significant associations made by GWAS.

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