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1
Oyola, Valdez Daniela Isabel. « Las polémicas sobre el Inca Garcilaso : textualidad, contra-escritura y novela en Poderes Secretos de Miguel Gutiérrez ». Bachelor's thesis, Pontificia Universidad Católica del Perú, 2019. http://hdl.handle.net/20.500.12404/14572.
Texte intégralRésumé :
En la presente investigación, analizo las construcciones ficcionales que en Poderes secretos
(2009) de Miguel Gutiérrez se realizan de figuras y eventos de gran centralidad que
pertenecen o tratan sobre el contexto temprano de la conquista y colonización de los Andes.
Sostengo que el narrador de la trama, escritor de una novela en proceso de creación,
construye una ficción de las denominadas “polémicas sobre la posesión de las Indias” a partir
de la polémica en torno a la biografía del Inca Garcilaso de la Vega y la autoría de sus
Comentarios reales, para demostrar la actualidad del ejercicio textual de la violencia colonial.
La cuestión del mestizaje, tema central de la discusión contemporánea sobre la identidad
nacional peruana, es concebida por la voz narradora como la continuación del problema del
indio originado en el contexto de la colonización americana, cuyo tratamiento se caracterizó
por ser polémico y textual. Mediante la construcción o, como concretamente entiendo, la
novelización de este fenómeno discursivo colonial, la novela, en tanto género literario, es
propuesta en la obra como el único espacio discursivo capaz de hacer resistencia a la
violencia de la Historia oficial, esto es, como un discurso textual constitutivamente político.Tesis
2
Spiewak, H. L. « Identifying novel secreted effectors of the type VI protein secretion system in Burkholderia cenocepacia ». Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/11777/.
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Port, Gary C. « Exploring the Listeria monocytogenes secretome : identification and functional characterization of novel virulence factors and secretion systems / ». Thesis, Connect to this title online ; UW restricted, 2007. http://hdl.handle.net/1773/4981.
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Herrera, Manzo Víctor. « Del repliegue al reflejo : El hipogeo secreto de Salvador Elizondo ». Tesis, Universidad de Chile, 2014. http://www.repositorio.uchile.cl/handle/2250/116122.
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Lefebvre, Karen. « Identification of novel PTEN-regulated secreted factors ». Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97210.
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PTEN, the most frequently mutated gene in human prostate cancer, is atumour suppressor that inhibits angiogenesis by regulating the expression ofseveral pro- and anti-angiogenic factors. The goal of this project was to identifynovel angiogenic factors and other secreted proteins that are regulated by PTEN.Proteomics techniques were employed to identify proteins that were differentiallyexpressed in the conditioned media of PTEN-null and PTEN-expressing humanprostate cancer cells. 16 proteins were identified, 4 of which were up-regulatedby PTEN and 12 of which were down-regulated by PTEN. Gene expressionanalysis and polysome profiling revealed that 2 proteins were transcriptionallyregulated by PTEN and 5 proteins were regulated at the level of translation.Three of the PTEN-regulated factors identified in this study, spondin 2 (SPO2),Zn-alpha-2-glycoprotein (ZAG), and cystatin C (CST3) are up-regulated invarious cancers and could be useful serum biomarkers for the diagnosis ofprostate cancer.PTEN est un gène supresseur de tumeur. Il est fréquemment muté chez leshumains ayant un cancer de la prostate. Un de ses rôles est d'inhiberl'angiogénèse en régulant l'expression de plusieurs facteurs pro- et antiangiogéniques.L'objectif de cette étude était d'identifier de nouveaux facteursangiogéniques et de nouvelles protéines secretées qui sont régulés par cetteprotéine. L'utilisation de différentes techniques protéomiques, sur le milieu deculture de cellules prostatiques cancéreuses, nous a permis d'identifier 16protéines ayant des niveaux d'expression différents selon que la protéine al'étude, PTEN, était ou non exprimée. Parmi elles, 4 ont un niveau d'expressionmoindre en présence de la protéine PTEN alors que les 12 autres présentent unniveau d'expression plus élevé. L'analyse du profil de polysomes et del'expression génique pour 7 d'entre elles montrent que la protéine PTEN enrégule deux au niveau transcriptionnel et cinq au niveau traductionnel. La forteexpression de trois protéines identifiées dans cette étude, spondin 2 (SPO2), Znalpha-2-glycoprotein (ZAG), et cystatin C (CST3), dans plusieurs cancers pourraitles qualifier comme nouveaux biomarqueurs dans le diagnostique du cancer de laprostate.
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McClenaghan, Neville Hugo. « Studies of novel insulin-secreting cell lines ». Thesis, University of Ulster, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284850.
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Trauth, Erin. « Tumbleweed Road : A Novel ». Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1794.
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Tumbleweed Road is a novel that began as a short story in a fiction workshop many years ago. The novel is set in the contemporary American South and traces one tumultuous summer in the life of a 14-year-old girl named Carolina Wells. The plot of the story is as follows: Carolina, a 14-year-old girl from Crow, Florida, does not understand her mother and remembers little about her past. In the story, we meet Carolina, her mother, "Mama," and two brothers, Johnny and Austin. Carolina does not understand her mother and her wild nature. At home, Carolina is forced to care for her two younger brothers. Carolina's father is long gone out of the picture, and Carolina was always told by her mother that she has no father - no one worth speaking of, anyway. Carolina can't remember why her father is gone, but remembers the fight that caused him to leave, and she blames her mother entirely for his leaving when she was just a toddler. Carolina questions her Mama about the disappearance of her father, but she refuses to even speak his name. Carolina desperately wants normalcy, family, and love - through a series of life-changing events involving a range of characters, including a spiritual woman across Tumbleweed Road, a mysterious girl named West and an old friend named Cade, this novel is about Carolina's quest to find her place in this world.
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Trezza, Alfonso. « A novel computational way to unlock drug targets deep and transient secretes ». Doctoral thesis, Università di Siena, 2019. http://hdl.handle.net/11365/1072788.
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Sargsyan, Ernest. « Characterization of ERp29, a novel secretion factor of endoplasmic reticulum / ». Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-337-X/.
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Ribeiro, Furtado Ana Rita. « A novel Chlamydia pneumoniae secreted protein with putative deubiquitinating activity ». Paris 7, 2010. http://www.theses.fr/2010PA077085.
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Chlamydia pneumoniae est une bactérie pathogène pour l'Homme. Cette espèce est un des principaux agents bactériens responsables de pneumopathies atypiques communautaires. Elle est également associée à des maladies chroniques comme l'athérosclérose. La multiplication des bactéries a lieu dans un compartiment délimité par une membrane, l'inclusion. Elles sont également capables de déjouer des défense; de l'hôte, et de détourner certaines des fonctions cellulaires à leur profit. L'appareil de sécrétion, dit de type trois (STT) joue à ce niveau un rôle prépondérant. Ce travail constitue la première étude de la protéine hypothétique de C. Pneumoniae, CPn0483. Cette protéine est un nouvel effecteur de la sécrétion de type III, conservée chez les Chlamydophila et absente des Chlamydia. CPn0483 présente le domaine OTU, qui peut conférer une activité de protéase à cystéine Bien que nous n'ayons pas démontré cette même activité contre des substrats d'ubiquitine, l'interaction de CPn0483 avec des sondes d'ubiquitine suggère fortement que CPn0483 puisse posséder l'activité de désubiquitination. Également, nous avons confirmé l'interaction entre CPn0483 et NDP52. À l'heure actuelle, nous testons la signification biologique de cette interaction au cours de l'infection de cellules eucaryotes par C. Pneumoniae. CPn0483 pourrait donc jouer un rôle important dans l'adaptation des Chlamydophila à leurs hôtesChlamydia pneumoniae is an obligate intracellular bacterial pathogen that is a causative agent for several human respiratory diseases and is also associated with chronic diseases, such as atherosclerosis. These bacteria survive within a membrane compartment, the inclusion, from where they are capable of diverting host cellular mechanisms for their own benefit. As other Gram-negative pathogenic bacteria, C. Pneumoniae possess genes coding for a type III secretion (TTS) System that allows translocation of bacterial proteins into their host. These proteins are of great interest because of their possible role in virulence and persistence within the host. We have identified the chlamydial protein CPn0483 as a type III secretion substrate. The séquence analysis of CPn0483 and its orthologs in chlamydiae led to the identification of an ovarian tumor (OTU) protease motif in their amino termini. Members of the OTU family of proteases that are found in eukaryotes and viruses, have been shown to have deubiquitinase activity. CPn0483 reacts with activity-based probes directed against deubiquitinases, further supporting the hypothesis that this bacterial protein has deubiquitinase activity. A yeast two-hybrid screen identified NDP52 (nuclear dot protein 52) as a protein capable of interacting with CPn0483. We were able to validate a NDP52 as protein partner of CPN0483 by immunoprecipitation and GST-pulldown. Thus, we have identified a novel type III effector protein of Chlamydia pneumoniae and one of its cellular targets, the protein NDP52. Considering its kinetics of expression, CPnQ483 could play a role late in the infectious cycle, or very early during the next round of infection
11
Iglesias, Marisa C. « Secret Servants : Household Domestics and Courtship in Eliza Haywood’s Fiction ». Scholar Commons, 2008. https://scholarcommons.usf.edu/etd/310.
Texte intégralRésumé :
In Eliza Haywood's fiction, as in eighteenth-century Britain, social restrictions repress the sexual desires of upper class women and men. Therefore, the secret desires of this social class often rely on a different group: domestic servants. Sometimes acting as confidants and other times as active players in the scheming, these servants are privy to the inner secrets of the households in which they live. In Haywood's Love in Excess (1719), Lasselia (1723), Fantomina (1725), and The History of Miss Betsy Thoughtless (1751), the servant class plays significant roles in the narratives.
Since the role of the servant is the central issue in my interpretation of Haywood's works, the historical background of the relationship between master and servant in the eighteenth-century is significant to my investigation. Conduct books, a popular genre of the times, were written to offer practical instruction to domestic servants. Haywood's A Present for A Servant Maid; or the Sure Means of gaining Love and Esteem (1743), offers a view of Haywood's own attitude toward the servant class.
In addition to her career as a writer of amorous intrigue, Haywood worked as both actress and playwright, and, because of her experience, elements of the stage can be seen in her works. I explore the influence of the theatre in Haywood's fiction and connect it to the prominent role of servants in her work.
Though Haywood demonstrates that the servants' loyalty can be bought for the highest price, they are not ruled by the same sexual passion as are their employers. This area is of particular interest to my study. I explore whether the motive of financial gain is greater than sexual desire, or whether it is an awareness that aristocrats are not truly available to the servant class that accounts for the differences in erotic responses. Additionally, I explore how servants affect Haywood's narrative by acting as agents of change and argue that the social restrictions placed on the upper class and the awareness of the sexual freedoms the servant class bring master and servant closer together.
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Green, Mike. « Social critique in the major novels of John Wyndham, civilization's secrets and nature's truths ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ47760.pdf.
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Moon, Hai-Sle. « Novel grooved substrata stimulate macrophage fusion, CCL2 and MMP-9 secretion ». Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/56295.
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Monocyte-derived macrophages arrive early at a newly implanted device and affect the performance of implants by regulating immune responses. Macrophages are “plastic” cells that exhibit a spectrum of functions between two quintessential phenotypes: (1) the classically activated (M1) phenotype associated with classical inflammatory responses and (2) the alternatively activated (M2) phenotype involved in wound healing or immunoregulatory behavior. Rough surface topographies on implants attract macrophages but the influence of topography on macrophage fusion to produce multinucleated giant cells (MGCs) and foreign body giant cells (FBGCs) is unclear. Previous studies have shown topography induced macrophage polarization and changes in cell shape as well as differential activation of cell signaling pathways. In this study, the effects of novel grooved substrata, G1 and G2, on changes in cell shape, gene expression, cyto/chemokine secretion and cell fusion were studied. G1 and G2 surfaces were fabricated by anisotropic etching of silicon <110> crystals, without the use of photolithographic patterning, and extensively characterized by optical profilometry to determine the roughness parameter Ra and isotropy parameters Str and Sal (G1: Ra 0.10 μm, Str 0.03, Sal 2.1 μm; G2: Ra 1.2 μm, Str 0.08, Sal 5.8 μm). RAW 264.7 macrophages were cultured on G1, G2, and smooth control (Pol) epoxy substrata for one and five days. Cells on the grooved surfaces exhibited cell morphology similar to M2 macrophages that were produced by IL-4 treatment. Cell alignment with the grooves increased with surface directionality and roughness as well as time in culture. Expression of macrophage chemoattractants CCL2 and CCL4 increased at the gene and protein level and the secretion of fusion mediators CCL2 and MMP-9 increased with time on the grooved surfaces. Relative to the Pol surface, an increased proportion of multinucleated cells was observed on the grooved surfaces at Day 5. Collectively, these in vitro results demonstrated that topography dependent macrophage responses resulted in differential secretion of macrophage attractant chemokines and soluble mediators involved in cell fusion that may explain the observed accumulation of macrophages and MGCs on rough surfaced implants in vivo.Dentistry, Faculty of
Graduate
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Wu, Yue. « Novel bioactive peptides from the defensive skin secretions of selected frogs ». Thesis, Queen's University Belfast, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.728833.
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In the course of this research, skin secretions from three species of frogs, Gunther's frog, Hylarana guentheri, the edible frog, Pelophylax kl. esculentus and the Hejiang odorous frog, Odorrana hejiangensis, were analysed by a range of molecular techniques. Three novel peptides, QUB2495 from the brevinin-1 family, QUB2950 from the brevinin-2 family and a bradykinin-related peptide, QUB1400, were discovered and confirmed in the skin secretion by use of MS/MS fragment sequencing. After this, peptides were synthesised, purified and used in a series of bioactivity assays, such as antimicrobial assays, a haemolysis assay, anticancer cell assays and smooth muscle assays. QUB2495 from Gunther's frog, Hylarana guentheri, display high potency and broad-spectrum of activity against bacterial and cancer cells, however, with high toxicity. QUB2950, from the skin secretion of the edible frog, Pelophylax kl. esculentus, was expected to present broad-spectrum antimicrobial activities and high selectivity, displayed little of these effects. Synthetic analogues, K2991 in which negative amino acids were replaced by Lys showed greatly increased charge, and L3180, in which charge and hydrophobicity are both enhanced by amino acids replacement. Both K2991 and L3180 showed increases in antimicrobial activity and L3180 displayed increased potency against bacterium, cancer cell line and normal cell. QUB1400, which was obtained from the skin secretion of Odorrana hejiangensis, displayed the ability to weakly contract the smooth muscles of rat bladder and uterus.
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Chim, Shek Man. « Identification and characterization of novel secreted factors involved in bone remodeling ». University of Western Australia. School of Surgery, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0110.
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[Truncated abstract] Bone remodeling is an important process to maintain mechanical integrity. It is accomplished by two important steps, bone resorption followed by new bone formation. Osteoclasts and osteoblasts are the principal cells in bone resorption and bone formation, respectively. A multitude of local and systemic factors regulates this process by controlling the cellular activities in bone remodeling compartments (BRC). An imbalance of osteoblastic bone formation and osteoclastic bone destruction will result in the development of skeletal diseases. Recent studies suggested that angiogenesis is closely associated with bone remodeling. The vasculature in bone is important for skeletal development, growth and repair. During endochondral ossification, cartilage is invaded by blood vessels which bring in osteoblast and osteoclast precursor cells, nutrients, growth factors and differentiation factors. During fracture repair, it has been demonstrated that mature osteoclasts produce heparanase which can degrade heparin sulfate proteoglycans, a major component in extracellular matrix (ECM). The process leads to the release of heparin-binding growth factors including vascular endothelial growth factor (VEGF), a potent angiogenic factor which contributes largely to local angiogenesis. In recent studies, endothelial cells have been found to produce bone morphogenetic protein (BMP)-2 and BMP-4 when they are subjected to mechanical stimuli, or a hypoxia environment. Conversely, inhibition of angiogenesis has been shown to prevent fracture healing. In a distraction osteogenesis model, either inhibition of angiogenesis or disruption of the mechanical environment prevents normal osteogenesis and results in fibrous nonunion. .... A total of 42 mice from F1 and F2 generations were genotyped as transgene positive. Preliminary analysis using radiography did not reveal any difference between the gross structures of transgenic and wild type mice. Interestingly, the preliminary histology revealed a decrease in trabecular bone and an increase of lipid space in metaphysis of transgenic mice overexpressing EGFL6. However, further studies will need to be carried out to investigate the role of EGFL6 in angiogenesis and adipogenesis using a transgenic mice model. This will be a prime focus of future work. Collectively, the results presented in this thesis have identified EGFL6, a member of the EGF-like family, as a potential angiogenic factor which may play an important role in bone remodeling. EGFL6 has been found to be expressed highly in calvarial osteoblasts and upregulated during primary murine osteoblast differentiation. EGFL6 has been 8 characterized to be a secreted homomeric complex. More importantly, EGFL6 has been shown to induce angiogenic activity in endothelial cell migration, tube formation and in vivo chick embryo chorioallantoic membrane assay. Furthermore, conditioned medium containing the EGFL6 recombinant protein was shown to induce phosphorylation of ERK in endothelial cells. Inhibition of ERK impaired EGFL6-induced ERK activation and endothelial cell migration. Taken together these studies raise the possibility that EGFL6 has a potential role in angiogenesis, and mediates a paracrine mechanism of cross-talk between vascular endothelial cells and osteoblasts during osteogenesis. An understanding of this process offers the potential to facilitate the development of therapeutic treatments for bone disease.
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Ng, Aylwin Chun Yeen. « The vaccinia virus A41L gene encodes a novel secreted immunomodulatory factor ». Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299018.
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Kupzig, Sabine. « Identification and characterisation of two novel proteins of the secretory pathway ». Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245577.
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Long, Qilin. « Biological activities and antidiabetic potential of novel peptides from frog secretions ». Thesis, Queen's University Belfast, 2018. https://pure.qub.ac.uk/portal/en/theses/biological-activities-and-antidiabetic-potential-of-novel-peptides-from-frog-secretions(032f6f90-8903-46fe-b26b-ac5b4dfaed78).html.
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The utilisation of natural products as drugs for the treatment of diseases and injuries has developed for thousands of years, but the current pharmaceutical system is predominately occupied by chemical-based drugs, while natural products are rarely applied. Since the widespread of antibiotic resistance and prevalence of chronic and malignant diseases (such as diabetes and cancers), there has been a significant rise of interest in discovering novel drug candidates with potent efficiency in treating these diseases. The amphibian skin, a special morphological and physiological organ, acts as the first line of defence against physical stimuli and lethal invasions. It is a rich source of pharmacological alternatives, some of which possess the potential to be developed in medical applications. In this study, both genomics and proteomics techniques have been used to study the frog skin secretions from the Burmeister’s leaf frog, Phyllomedusa burmeisteri; the hylid frog, Phyllomedusa sauvagei and the Chinese tiger frog, Hoplobatrachus rugulosus. More specifically, the molecular cloning strategy was performed to isolate target mRNAs, establish corresponding cDNA libraries and eventually clone unique peptide precursor-encoding cDNA sequences. Also, the mature peptides were analysed and confirmed via RP-HPLC, MALDI-TOF mass spectrometry and MS/MS fragmentation sequencing. After the peptide primary structure characterisation, synthetic replicates of each peptide were purified before applied for further secondary structural analysis and biofunctional assessments. The secondary structure conformations were determined by circular dichroism, and the functional analysis in this study includes the antimicrobial assay, MTT assay, haemolysis assay, insulinotropic assay and GLP-1 releasing assay. This study reports the isolation, identification and characterisation of one phylloseptin peptide Phylloseptin-PBu, one dermaseptin peptide Dermaseptin-PS1 and four tigerinin peptides (Tigerinin-HR1 to Tigerinin-HR4), they exhibited distinct biological activities. In Chapter 3, the detailed function and correlative mechanisms of novel phylloseptin peptide Phylloseptin-PBu were described. We showed that Phylloseptin-PBu could induce a dose-dependent insulinotropic activity in BRIN-BD11 cells, which is regulated by ATP-sensitive potassium channel depolarisation triggered extracellular calcium influx and GLP-1 receptor-initiated PKA signalling activation. In Chapter 4, the novel Dermaseptin-PS1 was demonstrated to possess anticancer capability in U251MG cells through the induction of intrinsic apoptosis at low concentrations (10-6M), but disrupting the cell membranes at high concentrations (≥10-5 M). In Chapter 5, GLP-1 release activity was observed after the treatment of peptide concentration gradient of four novel tigerinin peptides (Tigerinin-HR1 to Tigerinin-HR4) in STC-1 cells. These discoveries enriched the foundational knowledge of biological peptides from these three-frog species and might contribute to future drug development. This thesis includes six chapters, the Chapter 1 and Chapter 2 are general introduction and general materials and methods, respectively; the Chapter 3 to Chapter 5 are specific experimental chapters; and the Chapter 6 is general discussion chapter.
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Wasmeier, Christina. « Molecular cloning of phogrin, a novel insulin secretory granule membrane protein ». Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627383.
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Pan, Hao. « Studies on novel bioactive peptides from the skin secretion of amphibians ». Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709692.
Texte intégralRésumé :
Over many decades, naturally-occurring substances have been considered as an integral part of the treatment of human diseases. Skin secretions from amphibians play an important role for sourcing such agents with therapeutic potential. Amongst all types of substances discovered from amphibian skin secretion, peptides represent a large family of bioactive molecules with distinctive biological functions. To date, more than 2000 host defence peptides have been studied and many of them possess antimicrobial, antifungal or anticancer properties. In the present study, bioactive peptides have been isolated from skin secretions of four amphibians, the green tree frog Litoria caerulea, the white-lipped tree frog Litoria infrafrenata, the green and golden bell frog Litoria aurea and the European edible frog Rana esculenta. Amongst three bioactive peptides, three belong to the neuromedin U family and the other is a brevinin analogue. By using genomic and proteomic techniques, biosynthetic precursor-encoding cDNAs from each species were selectively cloned. The chemical structures of mature peptides was confirmed by MS/MS fragmentation sequencing and reverse phase HPLC. Biological functions of their synthetic replicates were screened in functional assays, including smooth muscle preparations and minimum inhibitory concentration assays for determining effects on microorganism growth.
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Laux, Adam Gabor. « MD* : A novel Molecular Dynamics approach to reveal the Target/small-molecule interaction secrets ». Doctoral thesis, Università di Siena, 2022. http://hdl.handle.net/11365/1203816.
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Abstract
In 1957, John Kendrew determined successfully the atomic structure of the myoglobin. Since, the scientific community increased the interest towards the knowledge of how the macromolecular structures are able to fold, move and interact inside the biological environment. To know the molecular basis of how a biological system works is a key step to reveal the secrets of the life. Molecular dynamics (MD) simulation, first developed in the late 60s, has advanced from simulating gases as elastic collisions between hard spheres to complex biological systems formed by thousands of atoms. However, several limits occur, such as: computational time, resource usage, non-feasibility etc. Automation, algorithm research and standardizations are crucial in order to curb cost of resources and achievement of results. In particular, accelerated search methods in the phase-space are increasingly studied to overcome the present barriers of IT capabilities.
In this thesis, we expose a novel and innovative approach of MD, named, Molecular dynamics-star (MD*), MD* is an accelerated binding/unbinding path finding MD algorithm based on the semantics from Artificial Intelligence (AI) Astar (A*) informed-search algorithm. MD* is implemented in GROMACS with control and evaluation cycles written in python for the accelerated simulation. The viability of MD* was evaluated simulating the binding/unbinding process of the LUSH protein/Ethanol co-crystal. The MD* simulation showed an accurate overlapping of the ethanol binding pose compared with the crystal, revealing its reliability. Our work, could be open novel frontiers in computational biochemistry field, providing the molecular basis of biological system interactions.
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Chadha, Marcus J. « Novel techniques for the characterisation of exopolysaccharides secreted by lactic acid bacteria ». Thesis, University of Huddersfield, 2009. http://eprints.hud.ac.uk/id/eprint/8749/.
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This project investigated the structures and physical characteristics of exopolysaccharides (EPSs) secreted by lactic acid bacteria. The structure of a novel exopolysaccharide (EPS) produced by Lactobacillus acidophilus 5e2 has been characterised. Analysis of the anomeric region of the H-NMR showed that the repeating oligosaccharide contained seven monosaccharides. GC-MS showed the structure to consist of D-glucose, D-galactose and D-N-acetyl-glucosamine in a molar ratio of 3:3:1. The linkage analysis showed that there were two terminal, three di-linked and two tri-linked monosaccharides, and in collaboration with data generated from a series of D-NMR experiments, an overall structure was determined. The weight-average molecular weight (Mw) of the EPS secreted by Lactobacillus acidophilus 5e2 when grown in skimmed milk was monitored during extended fermentation times. During the exponential growth phase, the increase in Mw closely followed the increase in yield of EPS. Under the fermentation conditions applied in this study, few if any new polysaccharide chains were formed during this growth phase despite a twenty five-fold increase in the cell count; almost the entire increase in yield can be accounted for by an increase in chain length. These results suggested that synthesis of new EPS chains is switched off during the exponential and stationary phase of fermentation. The increase in yield observed in this period is a consequence of the bacteria's ability to extend existing chains right up to the mid-stationary phase. These results raise questions about the factors that control EPS production and chain length. Depolymerisation techniques have been shown to reduce the Mw of the polysaccharide in a controlled manner. The H-NMR results have shown that the physical methods, constant pressure and ultrasonic disruption break the EPS randomly through the repeating oligosaccharide unit; polydispersity data suggests that the breakages were occurring midchain. A change to the peaks in the anomeric region of the H-NMR spectrum showed that depolymerisation, by acid hydrolysis, was chemically modifying the EPS structure. The approximate intrinsic viscosities of the EPS produced by Lactobacillus acidophilus 5e2 were determined to range between 0.6–2.0 dL g-1 for the Mw range of 1.59x105 – 4.78x105 g mol-1. A capillary zone electrophoresis method was developed to determine the monosaccharide composition of two EPS samples. The method successfully determined D-glucose and Dgalactose, but a peak for D-N-acetyl-glucosamine was not seen. The method was sensitive compared to current techniques, but not as low as using a HP-AEC-PAD. A novel method using LC-MS was developed for the linkage analysis of EPSs. Methylation, hydrolysis and reductive amination were used to derivatise the polysaccharide, and the fragmentation patterns were examined to determine the different linkage positions. Due to undesirable further fragmentation the method could not unequivocally differentiate between the different linkage positions, but the method was capable of resolving the monosaccharides residues with different linkage positions, at approximately the correct relative ratio.
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Ge, Beier. « Novel peptides from the defensive skin secretion of Asian and American frogs ». Thesis, Queen's University Belfast, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.726353.
Texte intégralRésumé :
Anurans have lived on earth for more than 300 million years. During this long period of time, they learned how to adapt to the environment and defend against microorganisms. Amphibian skin secretions generally contain complex peptidomes. These skin peptides constitute the first line of defence of amphibians against bacteria and fungi. Until now, more than 600 antimicrobial peptides (AMPs) from amphibians have been authenticated. AMPs selectively retard bacterial growth and kill bacteria. Compared with conventional antibiotics, AMPs have a number of clinical application advantages. Chapter 3 describes the study of two AMPs from Phyllomedusa sauvageiand Phyllomedusa hypochondrialis, named QUB2897 and QUB2869.These two peptides were synthesised by a solid phase peptide synthesis method and were purified by HPLC. A Q-TOF mass spectrometer was used to determine the peptides purity. Staphylococcus aureus (S.aureus), Escherichia coli (E.coli) and Candida albicans (C.albicans) were used to test the antimicrobial activities of QUB2897 and QUB2869 and horse blood was used to test their haemolytic activities. Both peptides were found to possess antimicrobial and haemolytic activities and they also had anti-cancer cell proliferation activity. Chapter 4 describes three novel peptides identified as QUB2897 and QUB2869 metabolism products from rat urinary bladder and ileum smooth muscle. The novel peptides, named QUB 2208 and QUB2179, were found as products of QUB2897 and QUB2869 metabolism of rat bladder smooth muscle, respectively. The novel peptide, named QUB501,was identified as a metabolite of both QUB2897 and QUB2869 by rat ileum smooth muscle. Using solid phase peptide synthesis (SPPS), these three novel peptides were successfully synthesised. QUB2208 and QUB2179 displayed more potent antimicrobial activities than their parent peptides, QUB2897 and QUB2869, respectively. The bioactivity of QUB501, however, was lower than that of the parent peptides. Chapter 5 describes the isolation and identification of two novel peptides, named QUB2582 and QUB1889, from the defensive skin secretion of the toad, Bombina maxima. The two peptides were synthesised by solid phase peptide synthesis and were purified by HPLC. The Q-TOF mass spectrometer was used to determine the peptides purity. Both peptides were found to possess anti-cancer cell proliferation activities.
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Sanders, Kelly Louise. « Molecular mechanisms of insulin secretion : identification of a novel glucose regulated protein ». Thesis, University of the West of England, Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.585489.
Texte intégralRésumé :
Diabetes mellitus has reached epidemic proportions and affects more than 200 million people world-wide. It is a heterogenous metabolic disorder, defined by the presence of hyperglycaemia. This study sought to use the application of proteomics to elucidate the mechanisms involved in glucose stimulated insulin secretion in MIN6 pancreatic p--cells, by determining and identifying differential expression of proteins in response to glucose stimulation (i) in a global context, and (ii) at the insulin-containing vesicle level. Optimisation of 2-dimensional gel electrophoresis (2DGE) resulted in the determination of the MIN6 p-cell proteome and the identification of 84 different proteins. Many proteins were found to be differentially expressed as a result of glucose stimulation, reflecting the enhancement of insulin exocytosis. These include the up-regulation of molecular chaperones involved in protein biosynthesis, such as T complex protein, which mediates folding of actin and tubulin, and heat shock cognate protein 70, which is involved in uncoating of clathrin coated vesicles. Proteins known to be involved in the transport of insulin- containing vesicles from the storage pool to the readily releasable pool, such as actin, tubulin B5 and tubulin alpha were also identified to be up regulated. For an increase in insulin biosynthesis to manifest itself as a rise in glucose-stimulated insulin secretion, translocation of insulin-containing vesicles from the Golgi region to the plasma membrane, and maturation of vesicles are required. Proteomic analysis of the insulin-containing vesicle was undertaken to obtain a better understanding of vesicle regulation. To date 24 proteins have been identified including the heat shock cognate protein - involved in uncoating of clathrin- coated vesicles; vacuolar ATP synthase subunits, which maintain a low intravesicular pH, important for proinsulin conversion and storage of zinc-insulin hexamers, and glucose-regulated proteins 54, 78 and 94. Several proteins not directly attached to vesicles, but involved in vesicle cycle regulation co purified with vesicles for example actin and tubulin. Both actin and tubulin form core complex with synapsin proteins, synaptotagmin and SNAP-25 during vesicle docking thus explaining their presence on insulin vesicles. Proteomic analysis of the MIN6 pancreatic p-cell also identified translationally controlled tumour protein (TCTP) to be significantly up-regulated in response to glucose stimulation, leading to further investigation into its role and function. This is the first study (i) to identify the presence of TCTP in the p-cell by proteomic analysis and (ii) to investigate the regulation and function of TCTP in the pancreatic p-cell. From the data presented TCTP has been identified as a novel glucose-regulated protein, whose regulation involves post-translational modification by both phosphorylation and glycosylation. These post-translational modifications are regulated and induced by glucose, and have been demonstrated to affect its cellular localisation, with an increase in the nuclear localisation of TCTP in response to glucose stimulation, as well as increased localisation with the cytoskeletal protein actin. Additionally, reducing TCTP protein expression using siRNA resulted in enhanced p-cell death. Preliminary studies also suggest that TCTP may be involved in the process of insulin secretion, with a significant decrease in insulin secretion observed as a result of reduced TCTP protein expression. Data presented in this study illustrate that TCTP is not only vital to p-cell survival, but potentially is a key player in GSIS, at multiple levels; from the regulation of gene transcription, to the trafficking and release of the insulin-containing vesicles.
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Tse, Lai-yin. « Identification of a novel PHI receptor in goldfish Carassius Auratus : implications of conservation of PHI structure in vertebrates / ». Click to view the E-thesis via HKUTO, 1999. http://sunzi.lib.hku.hk/hkuto/record/B42575357.
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Rudomanova, Valeriia. « Unraveling the Secrets of Kidney Disease : Novel Molecular Mechanisms of Acute and Chronic Kidney Injury ». University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1623250686588821.
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Popescu, Andrei-Alin. « Novel algorithms and methodology to help unravel secrets that next generation sequencing data can tell ». Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/58571/.
Texte intégralRésumé :
The genome of an organism is its complete set of DNA nucleotides, spanning all of its genes and also of its non-coding regions. It contains most of the information necessary to build and maintain an organism. It is therefore no surprise that sequencing the genome provides an invaluable tool for the scientific study of an organism. Via the inference of an evolutionary (phylogenetic) tree, DNA sequences can be used to reconstruct the evolutionary history of a set of species. DNA sequences, or genotype data, has also proven useful for predicting an organisms’ phenotype (i. e. observed traits) from its genotype. This is the objective of association studies. While methods for finding the DNA sequence of an organism have existed for decades, the recent advent of Next Generation Sequencing (NGS) has meant that the availability of such data has increased to such an extent that the computational challenges that now form an integral part of biological studies can no longer be ignored. By focusing on phylogenetics and Genome-Wide Association Studies (GWAS), this thesis aims to help address some of these challenges. As a consequence this thesis is in two parts with the first one centring on phylogenetics and the second one on GWAS. In the first part, we present theoretical insights for reconstructing phylogenetic trees from incomplete distances. This problem is important in the context of NGS data as incomplete pairwise distances between organisms occur frequently with such input and ignoring taxa for which information is missing can introduce undesirable bias. In the second part we focus on the problem of inferring population stratification between individuals in a dataset due to reproductive isolation. While powerful methods for doing this have been proposed in the literature, they tend to struggle when faced with the sheer volume of data that comes with NGS. To help address this problem we introduce the novel PSIKO software and show that it scales very well when dealing with large NGS datasets.
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謝禮賢 et Lai-yin Tse. « Identification of a novel PHI receptor in goldfish Carassius Auratus : implications of conservation of PHIstructure in vertebrates ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B42575357.
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Williams, Michael. « Secretin-Modulated Potassium Channel Trafficking as a Novel Mechanism for Regulating Cerebellar Synapses ». ScholarWorks @ UVM, 2013. http://scholarworks.uvm.edu/graddis/241.
Texte intégralRésumé :
The voltage-gated potassium channel Kv1.2 is a critical modulator of neuronal physiology, including dendritic excitability, action potential propagation, and neurotransmitter release. However, mechanisms by which Kv1.2 may be regulated in the brain are poorly understood. In heterologous expression systems Kv1.2 is regulated by endocytosis of the channel from the plasma membrane, and this trafficking can be modulated by adenylate cyclase (AC). The goal of this dissertation was to determine whether AC modulated endocytic trafficking of endogenous Kv1.2 occurred in the mammalian nervous system. Within the brain, Kv1.2 is expressed at its highest levels in the cerebellar cortex. Specifically, Kv1.2 is expressed in dendrites of Purkinje cells (PC), the sole efferent neurons of the cerebellar cortex; Kv1.2 is also expressed in axon terminals of Basket cells (BC), which make inhibitory synapses to Purkinje cells. The loss of functional Kv1.2 in PC dendrites or BC axon terminals causes profound changes in the neurophysiology of Purkinje cells, and aberrant loss of Kv1.2 produces cerebellar ataxia. Therefore, the cerebellum offers a brain structure where Kv1.2 is abundant and has known and important roles in synaptic physiology. A candidate regulator of Kv1.2 trafficking in cerebellar synapses is the secretin peptide receptor: the receptor is also located in both PC dendrites and BC axon terminals, and ligand binding to the secretin receptor stimulates AC. Although secretin affects cerebellar neurophysiology and cerebellar dependent behavior, the mechanisms are not well resolved. By cell-surface protein biotinylation and subsequent immunoblot quantitation of secretin treated rat cerebellar slice lysates, secretin was found to decrease cell-surface Kv1.2. This effect could be mimicked by stimulating AC with forskolin, and could be occluded by inhibition of the secretin receptor, AC, or protein kinase A. The secretin receptor stimulated loss of surface Kv1.2 was not accompanied by decreased total Kv1.2 protein levels, but did involve enhanced channel endocytosis. Microscopy studies using two novel independent techniques provided evidence that both BC axon terminals and PC dendrites are sites of AC-stimulated Kv1.2 endocytosis. The physiological significance of secretin mediated suppression of Kv1.2 was supported by collaborative studies which found infusions into the cerebellar cortex of either a toxin that inhibits Kv1.2, or of secretin, enhanced eyeblink conditioning, a form of cerebellar dependent learning, in rats. These studies provided the first evidence that Kv1.2 is regulated by endocytic trafficking in the brain. However, to address the role of that trafficking in synaptic physiology requires knowledge about the determinants of Kv1.2’s endocytic potential, and non-destructive assays to measure Kv1.2 endocytosis in neural circuits. This dissertation therefore concludes with preliminary studies that explore an ancient motif regulating Kv1.2 trafficking, and that discuss a novel dual fluorescent fusion protein reporter of Kv1.2’s subcellular localization.
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Vega, Arancibia Andrea. « La adaptación de los elementos estructurales de la novela policial : enigma e investigador en Ceremonia Secreta ». Tesis, Universidad de Chile, 2005. http://www.repositorio.uchile.cl/handle/2250/110288.
Texte intégralRésumé :
Informe de Seminario para optar al grado de Licenciado en Lengua y Literatura Hispánica mención Literatura.El objeto que se pretende trabajar en el proyecto final es la nouvelle de Marco Denevi Ceremonia secreta. Esta obra recibió el Primer Premio en el concurso de cuentos realizado por la revista Life en 1960. La obra será trabajada usando el tema “La adaptación de los elementos estructurales de la novela policial: enigma e investigador, en Ceremonia Secreta”.
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Chen, Chen. « Studies on Selective Protein Loading onto Extracellular Membrane Vesicles of a Novel Cold-Adapted Bacterium, Shewanella vesiculosa HM13 ». Kyoto University, 2020. http://hdl.handle.net/2433/253331.
Texte intégralRésumé :
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第22495号
農博第2399号
新制||農||1076(附属図書館)
学位論文||R2||N5275(農学部図書室)
京都大学大学院農学研究科応用生命科学専攻
(主査)教授 栗原 達夫, 教授 小川 順, 教授 木岡 紀幸
学位規則第4条第1項該当
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Silverman, Judith Maxwell. « Identification of a novel secretion system in Leishmania : composition, mechanisms, and immune modulating properties ». Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/23492.
Texte intégralRésumé :
Human infection with protozoa of the genus Leishmania results in a spectrum of disease manifestations collectively termed the leishmaniases. These diseases involve a chronic infection of macrophages which display a deactivated phenotype. Various proteins secreted by leishmania are known to interact with host signaling molecules, bringing about activation of negative feedback loops. Some of these have been shown to block interferon-γ signaling and to inhibit macrophage microbicidal functions. Unlike the well characterized secretion mechanisms used by bacterial pathogens, the mechanism(s) by which leishmania and other eukaryotic pathogens secrete proteins into host cells has remained elusive. The overall aim of this project was to gain a more thorough understanding of host immune-modulation by leishmania, based on the hypothesis that much of these effects are mediated by secreted proteins. The project goals were to: 1) comprehensively identify the proteins secreted by leishmania, 2) determine the mechanism by which proteins are secreted from leishmania into host cells, and 3) determine the functional properties of leishmania secreted compounds. To achieve these goals, a global proteomic analysis of leishmania secreted proteins was carried out using quantitative mass spectrometry. This identified 358 bona fide leishmania secreted proteins many of which were orthologs of proteins considered to be markers of mammalian exosomes. Subsequent experiments confirmed that leishmania secrete exosomes into conditioned media. Comparative proteomics showed that exosomes account for at least 50% of protein secretion by leishmania. Furthermore, the results showed that the cargo profile of leishmania exosomes is influenced by changes in temperature and pH, similar to those experienced by promastigotes after host invasion. Microscopy of leishmania infected cells confirmed the novel finding that leishmania use exosomes to deliver proteins into host cells. Additional studies demonstrated that leishmania exosomes have immunosuppressive properties which, in a cargo dependent manner, modulate the responses of monocytes, dendritic cells, and T lymphocytes. These findings suggest that leishmania utilize exosomes in long-range cellular communication and immune-modulation. In conclusion, this research has significantly advanced the current knowledge of leishmania biology, through the identification of novel secreted molecules, discovery of a secretion system, and description of the immune-modulating effects of leishmania exosomes.
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Kenny, Brendan. « Analysis of the novel C-terminal secretion signal of the Escherichia coli haemolysin protein ». Thesis, University of Leicester, 1990. http://hdl.handle.net/2381/34435.
Texte intégralRésumé :
The release of a haemolytic toxin from some urinopathogenic strains of E. coli is unique in that it is the only reported polypeptide to be truly secreted from this Gram-negative organism. This secretion system comprises four genes on a contiguous, approximately 7.5Kb DNA fragment, encoding the toxin itself (HlyA, 107KD), two membrane localised export proteins (HlyB,D) and the cytoplasmic HlyC protein, whose only apparent function is to post-translationally activate the toxin. Recently, another unlinked gene, tolC, encoding a minor outer membrane protein has also been reported to be required for the export process together with HlyB,D. A novel feature of this system is the presence of a C-terminal targeting signal to direct HlyA from the cell. In this study I show that the HlyA C-terminal targeting signal can be harnessed to secrete the majority of both the mammalian prochymosin and the E. coli cytoplasmic, LacZ, proteins in an HlyB,D dependent manner. I have also shown that the efficiency of secretion dramatically decreases when either the C-terminal domain is reduced in size, from 23KD to 4KD, or as the "passenger" domain increases in size. These results suggest that the HlyA signal domain is composed of sequences required for both efficiency of secretion and targeting and that the secretion process is inhibited by heterologous passenger domains, the effect increasing with size presumably due to the adoption of more stable folded conformations. This study has also been concerned with the investigation into the nature of the novel hlyA targeting signal by deploying a series of in vitro mutagenesis methods (hydroxylamine, site directed and "saturation"), to introduce point mutations. This work has generated a bank of mutants, the analysis of which, has highlighted several residues essential for efficient secretion and also indicated a minimal region containing the signal motif. However, this information together with comparisons with other molecules carrying similar targeting signals have not yet identified a common signal motif.
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Dong, Yanjing. « Identification, molecular cloning and functional characterization of novel bioactive peptides from amphibian skin secretion ». Thesis, Queen's University Belfast, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.766285.
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Milwid, Jack Miles. « Discovery of novel anti-inflammatory proteins inspired by bone marrow mesenchymal stem cell secretions ». Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68517.
Texte intégralRésumé :
Thesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 114-133).
Bone marrow mesenchymal stem cells (MSCs) may soon become the first FDA-approved stem cell therapy for autoimmune and inflammatory disease. Our lab originally hypothesized that much of the therapeutic activity of MSCs may be attributed to molecules secreted by these cells. This thesis will test this hypothesis, with an emphasis on translational steps towards clinical product development, including the identification of novel proteins secreted by MSCs. The first part of the thesis consists of studies we performed to test whether MSC conditioned medium (MSC-CM) can treat rats undergoing cisplatin-induced acute kidney injury (AKI). When AKI rats were treated with MSC-CM, we observed a survival benefit and significant protection of renal function compared to controls. The second part of the thesis will describe the development of a device designed for sustained delivery of MSC secreted factors to dialysis-dependent AKI subjects. We tested these devices for cell function, stability and viability when subjected to conditions that model future clinical operation. Finally, inspired by the therapeutic capacity of MSC secreted factors, this thesis will conclude with the introduction of a new method that we developed to uncover novel anti-inflammatory proteins from MSCs. This method revealed four previously unidentified cytokine modulators, two of which we found significantly promote IL-1 0 and suppress TNF-a in mice challenged with endotoxin. When leveraged as novel therapeutics for lethal endotoxemic shock, these two most potent modulators protected mice and provided for a significant survival benefit compared to vehicle controls. Together, these results demonstrate the power of MSC secreted factors in the context of inflammatory disease, and propose new tactics for elucidating potent secreted products from cells.
by Jack Miles Milwid.
Ph.D.
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Wang, Yu. « Sphingosine kinase 1-interacting protein is a novel regulator of glucose-stimulated insulin secretion ». Kyoto University, 2017. http://hdl.handle.net/2433/226770.
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Tsang, Shun-Wa. « A novel secretory molecule, MAB-7, is required in ray morphogenesis of caenorhabditis elegans / ». View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?BIOL%202002%20TSANG.
Texte intégralRésumé :
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.Includes bibliographical references (leaves 116-121). Also available in electronic version. Access restricted to campus users.
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Lin, Hsuan-Yu. « Design, synthesis and testing of novel anti-cancer agents targeting secretory pathway calcium ATPase ». Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/12267.
Texte intégralRésumé :
Secretory pathway calcium ATPase (SPCA) 1 was found to be associated with basal-like breast cancers, which had the poorest prognosis with minimal therapeutic agents available. Increased expression of insulin-like growth factor receptor was identified in a study to possess a strong involvement in cancer initiation, proliferation and resistance to anti-cancer therapy. This finding had provided a window of opportunity to place SPCA1 as a new therapeutic target for basal-like breast cancer. The main aims were to fully understand the role of SPCA1 in basal-like breast cancer and to design, synthesise and test chemical compounds that would inhibit the growth of basal-like breast cancer cells in vitro. Additional focus was also placed on discovering sarcoplasmic-endoplasmic reticulum calcium ATPase (SERCA) inhibitors to streamline the drug discovery process. The use of molecular modelling, virtual screening, chemical synthesis and biological assays had assisted with the decision of selecting potential compounds. At least three out of seven tested compounds had an effect on the intracellular calcium signals. However, the potency and selectivity of these compounds would need to be improved to become better SERCA inhibitors. Therefore more future work is warranted to further refine the potency and selectivity of these compounds on the target receptors.
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Jin, Jinshan. « Characterization of SecA1 and SecA2 from Gram-positive pathogens and discovery of novel SecA inhibitors ». Digital Archive @ GSU, 2011. http://digitalarchive.gsu.edu/biology_diss/105.
Texte intégralRésumé :
Due to the emergence and dissemination of multidrug resistance, bacterial pathogens have been causing a serious public health problem in recent years. To address the existing drug resistant problem, there is an urgent need to find new antimicrobials, especially those against drug-resistant bacteria. SecA is the central component of Sec-dependent secretion pathway, which is responsible for the secretion of many essential proteins as well as many toxins and virulence factors. Two SecA homologues are indentified in some important Gram-positive pathogens. SecA1 is involved in general secretion pathway and essential for viability, whereas SecA2 contribute to secretion of specific virulence factors. The high conservation among a wide range of bacteria and no human counterpart make SecA homologues attractive targets for exploring novel antimicrobials. We hypothesize that inhibition of these SecA homologues could reduce virulence, inhibit bacteria growth, and kill bacteria. SecA1 and SecA2 from four different species were cloned, purified, and characterized. All these SecA homologues show ATPase activities, thus screening ATPase inhibitors might help to develop new antimicrobials. In this study, three structurally different classes of SecA inhibitors were developed and optimized: 1) Rose Bengal (RB) and RB analogs derived from systematical dissection RB and Structure-Activity relationship (SAR) study; 2) pyrimidine analogs derived from virtual screening based on the ATP binding pocket of EcSecA and SAR study; and 3) bistriazole analogs derived from random screening and SAR study. Several potent SecA inhibitors show promising enzymatic inhibition against SecA homologues as well as bacteriostatic and bactericidal effects. Two major efflux pumps of S. aureus, NorA and MepA, have little negative effect on the antimicrobial activities of SecA inhibitors, suggesting that targeting SecA could by-pass efflux pumps. Moreover, these inhibitors impair the secretion of important toxins of S. aureus and B. anthracis, indicating the inhibition of in vivo SecA function could reduce virulence. Target identification assays confirm that these inhibitors could directly bind to SecA homologues, and specifically identify SecA from whole cell lysate of E. coli and S. aureus, suggesting that these inhibitors are really targeting on SecA. These studies validate that SecA is a good target for development antimicrobials.
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Daniele, Joseph. « A Novel Proteolytic Event Controls Hedgehog Intracellular Sorting and Transport ». Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10294.
Texte intégralRésumé :
The protein Hedgehog (Hh) is a highly conserved, secreted ligand (and morphogen) capable of patterning many different tissues during development. Recently, Sonic Hedgehog (SHH) a human homolog of Drosophila Hh was found to be a causative agent in certain cancers. While several drugs are being developed to combat the binding of SHH to its receptor Patched or the Patched-target Smoothened, very little is known about how SHH is secreted from the producing cell, another site for therapeutic targeting. We report here the characterization of a novel proteolytic event and genetic pathway that controls Hh intracellular sorting and axon transport using the Drosophila eye imaginal disc as our model system. In fly larval photoreceptor neurons the developmental signal Hh is guided to the apical (retina) and basal (growth cone, GC) ends where secretion of the morphogen is an inductive factor in photoreceptor differentiation and establishment of eye/brain neural connections. The Hh secreted from the basal side induces lamina development while Hh secreted at the retina induces ommatidial development. Hedgehog processing consists of autocleavage from its 46 kDa form (HhU) to become a lipid-modified N-terminal signaling molecule (HhN; 19kDa) and a C-terminal molecule (HhC24; 24 kDa). Following autocleavage, a fraction of the C-terminal auto-cleavage product then undergoes a second cleavage event leading to 16 kDa (HhC16) and 9 kDa products. Nothing is known about the significance of the C-terminal “2nd cleavage” other than its occurrence in both fly and human tissue. In an effort to identify regulators of Hh sorting, we discovered that the HhC “2nd cleavage” is a determining factor in the sorting of the HhN signaling domain. That is, if a cell induces more cleavage (more HhC16) we observe more HhN in the apical domain. Likewise, if a cell inhibits 2nd cleavage (less HhC16) we see more basal HhN. Creation of a “2nd cleavage mutant” shows that this process has developmental significance. Further, biochemical characterization of the 2nd cleavage suggests it occurs in the ER after autocleavage and that HhC24 can exit the cell in a Golgi independent manner (via lipid droplets) while HhC16 remains intracellular. The ER exit of HhC24 appears to be controlled by a conserved PP2A (Mts) /PKB (Akt) kinase pathway which potentially regulates the size and number of lipid droplets produced. These findings are an important first step in understanding the intracellular sorting and transport of Hh and highlight new targets for the treatment of SHH-related cancers. The discovery of divergent modes of Hh secretion and the “2nd cleavage” open novel avenues for Hh research by offering an alternative, and very direct, line of attack in the treatment of Hh-related cancer.
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Wang, Pengwei. « KMS, a group of novel plant endoplasmic reticulum proteins involved in the early secretory pathway ». Thesis, Oxford Brookes University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515239.
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O'Brien, Graham James. « Molecular analysis of microcin 24 : Genetics, secretion and mode of action of a novel microcin ». Thesis, University of Canterbury. Plant and Microbial Sciences, 1996. http://hdl.handle.net/10092/6808.
Texte intégralRésumé :
Colicins and microcins are proteinaceous antimicrobial agents produced by members of the Enterobacteriaceae which are active against other members of this family. Colicin24 is a novel bacteriocin produced by a uropathogenic strain of Escherichia coli isolated at Christchurch Hospital. Through detailed genetic analysis of the DNA encoding this toxin and assaying the toxic activity, colicin 24 was re-classified as microcin 24 and has been shown to have a similar genetic organisation to that of colicin V and a novel mode of activity.
The region of DNA encoding microcin 24 was subcloned from pGOB34 into pBR322 generating pGOB18 (5.44kb). Mutagenesis, DNA sequencing and transcomplementation identified two regions with high sequence similarity and functional homology to the ColV transporters CvaA and CvaB. The insert DNA of pGOB18 was sequenced in both directions and has been found to contain 5267bp encoding five open reading frames, mdbA, mtft, mtfS, mtfA and mtfB, forming three operons mdbA, mtfI/mtfS and mtfA/mtfB all of which were transcribed in the same direction. The predicted protein products of all the open reading frames except mtfB were confirmed by expressing the genes in minicells. Further mutagenesis and trans-complementation has identified mdbA as a cis acting positive regulatory gene with sequence similarity to the histone-like proteins. The mtfI and mtfS genes were confirmed as the Mcc24 immunity gene and the Mcc24 structural gene respectively. The genes mtfA and mtfB were found to encode the transport proteins homologous to CvaA and CvaB respectively, with mtfB encoding a protein which is a member of the ABC family of bacterial transporters. Transport also requires the TolC outer membrane protein. Analysis of the mtfS DNA sequence has identified a double glycine leader sequence, making MtfS the second microcin after ColV to belong to this class of peptide antibiotics. Experimental evidence suggested that unlike ColV, Mcc24 is inactive within the producing cell, however both toxins require the ABC transporter for post-translational modification of the pre-peptide.
The regulation of Mcc24 synthesis is controlled by the interaction between σs, Fur, and MdbA, encoded by the mdbA gene. Analysis of the promoter sequences has identified putative regions of DNA bending which might facilitate the binding of σs and MdbA. A Fur-box with good sequence similarity to the consensus Fur-box has been identified in the mtfI/mtfS promoter and is the proposed site for Fur binding.
The activity spectrum of Mcc24 is restricted to enteric bacteria and SernA, the MccE492 receptor, is also required as the receptor for Mcc24. Extracts of Mcc24 have been found to degrade both linearised and covalently closed circular DNA in vitro. The activity is absent in extracts from mtfS - strains, suggesting that Mcc24 inhibits the growth of sensitive cells by degrading DNA. The effect of Mcc24 expression on the virulence of E. coli was tested using the embryo lethality assay, however unlike ColV which increases the virulence of strains, the expression of Mcc24 did not appear to have a significant effect on E. coli virulence in this system.
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Li, Long. « Study on novel peptides in the skin secretions of Chinese frogs of the genus, Odorrana ». Thesis, University of Ulster, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398973.
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Chen, Dong. « Identification, molecular cloning and functional characterisation of novel bioactive peptide drugs from amphibian skin secretions ». Thesis, Queen's University Belfast, 2017. https://pure.qub.ac.uk/portal/en/theses/identification-molecular-cloning-and-functional-characterisation-of-novel-bioactive-peptide-drugs-from-amphibian-skin-secretions(a5d6ffd1-1440-4528-af7a-4f6d9e244f76).html.
Texte intégralRésumé :
Skin secretions of amphibians, which contain a large amount of bioactive compounds, play an essential role in their survival. For instance, some toxic or irritant secretions can protect them against predators. Due to the pharmacological and bioactive characteristics of the components in amphibian skin secretion, these secretions have been considered as one of the world’s richest source of such agents. In this study, the skin secretions of the frogs Odorrana livida, Hylarana latouchii and Phyllomedusa sauvagii were collected from the dorsal surface and immediately frozen in liquid nitrogen. Afterwards, a series of molecular techniques, including mRNA isolation, cDNA library construction, PCR, agarose gel analysis and DNA sequencing were applied. The novel peptide sequences were deduced from cloned cDNAs and then confirmed by using MALDI-TOF mass spectrometry and MS/MS fragmentation sequencing. Finally, three novel peptides were chemically-synthesised. The determination of the therapeutic bioactivities of the three novel peptides was carried out by a series of assays. QUB-1384, exhibited BK-receptor agonist-like functions which induced the contraction of rat bladder and uterus tissues. QUB-1906 is a Bowman-Birk inhibitor which could efficiently inhibit the activity of trypsin. The novel dermaseptin peptide, QUB-2949, had broad-spectrum anticancer activities against human cancer cell lines including PC-3 (ATCC-CRL-1435), U251MG (ecacc-09063001), H157 (ATCC-CRL-5802), MCF-7 (ATCC-HTB-22) and MDA-MB-435S (ATCC-HTB-129). Meanwhile, like other dermaseptin peptides, QUB-2949 showed effective growth inhibitory activity against the standard Gram-negative bacterium Escherichia coli (NCTC 10418), the standard Gram-positive bacterium Staphylococcus aureus (NCTC 10788), the pathogenic yeast Candida albicans (NCPF 1467), the drug-resistant bacterium Enterococcus faecalis (ATCC 29212), Methicillin-resistant Staphylococcus aureus (MRSA) (ATCC BAA-2094) and Pseudomonas aeruginosa (NCTC 13437). In addition, according to the results of haemolysis assay and HMEC-1 MTT assay, all the peptides exhibited low cytotoxicity. In conclusion, three novel peptides were found and assessed in this project. The multifunction and low cytotoxicity of these bioactive peptides make them promising candidates for natural drug discovery and provide new prospect for clinical treatments.
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Asada, Masanori. « Identification of a novel autoantibody against pancreatic secretory trypsin inhibitor in patients with autoimmune pancreatitis ». Kyoto University, 2008. http://hdl.handle.net/2433/135788.
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Taylor, Carolyn Valerie Livsey. « The endogenous cleavage sites, secretion, and activity of catestatin, a novel catecholamine release-inhibitory peptide / ». Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2001. http://wwwlib.umi.com/cr/ucsd/fullcit?p3025946.
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Koerner, Hannah Claire. « Defining a Micro-genre : Insular Friend Groups in Contemporary Literature, and What We Saw There : A Novel ». Ohio University Honors Tutorial College / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1492741467006626.
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Pan, Nan. « Studies on novel bioactive peptides and their precursors from the skin secretions of Australian Pelodryadinae frogs ». Thesis, Queen's University Belfast, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.557641.
Texte intégralRésumé :
The research presented in this thesis is centred on the transcriptomic, peptidomic and pharmacological analysis of bioactive peptides which have been isolated and characterised from Australian Pe/odryadinae Frogs. In this thesis, the lyophilised skin secretions from species of the Litoria genus of Australian Pe/odryadinae Frogs, L. caeru/ea, L. aurea and L. infrafrenata, have been studied using a rapid 3' - and 5' - RACE 'Shot-gun' cloning strategy for procurement of bioactive peptide precursor-encoding cDNAs, without causing any detrimental effects to the donor specimens. Two novel cDNAs encoding biosynthetic precursors of the neuropeptide analogue, caerulein, and several cDNAs encoding precursors of novel antimicrobial peptides, were identified for the first time. NCBI-BLAST searches revealed a unique pattern of strikingly-conserved (prepro-) regions within precursors in contrast to the sequences of obviously hypervariable mature peptide-encoding domains. This phenomenon does not only occur in species of the Australian hylid sub-family, Pe/odryadinae, but has also been.observed in Asian, European and North American ranids (sub-family Raninae) and South American hylids (sub family PhyIJomedusinae), indicating their probable origins from multiple duplications of an ancestral gene presumably before the fragmentation of Gondwana (ca. 150 million years ago). Surprisingly, there was only a limited degree of sequence identity between the caerulein precursors from two distantly-related frog lineages, Litoria and Xenopus,indicating a high degree of divergence of general gene product during natural selection but with a high degree of conservation of active mature peptide sequence-encoding domains. Synthetic replicates of bioactive peptides were accessed by pharmacological screening of several bioassays including antimicrobial, biofilm bactericidal, anticancer and erythrocyte cytotoxic potency analysis. The novel caerin peptide, which possessed two amino acid residue substitutions when compared with caerin 1.12, exhibited a high degree of efficacy in antimicrobial, biofilm eradication, time-kill kinetic and anticancer assays with a high degree of selectivity for prokaryotic over eukaryotic cells. Less effective, but still active aurem peptides would be restricted for use by their inherent cytotoxicity. Frenatin peptides, as predicted, displayed relatively poor functionality. Iris hoped that the novel data generated from studies described in this thesis will, in the future, provide a modicum of support for predictions of fundamental peptide function and the evolutionary relationships of peptides discovered in amphibian skins. Peptides from Australian Pelodryadinae frogs described here, may require additional modifications prior to consideration as therapeutic agents, primarily to help eliminate side-effects through reducing cytotoxicity.
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Power, Gavin Jude. « Isolation, structural characterisation and mechanisms of action of novel insulin-releasing peptides from amphibian skin secretions ». Thesis, University of Ulster, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.554281.
Texte intégralRésumé :
Amphibian skin secretions are considered to be one of the richest resources of bioactive molecules in the animal kingdom for pharmaceutical prospecting. This thesis has investigated amphibian skin peptides of eight different species of anurans (frogs and toads) for insulin-releasing and anti-diabetic properties. The skins of Pseudis paradoxa, Hylarana guntheri, Hylomantis lemur and Leptodactylus laticeps, were tested for the presence of peptides with stimulatory effects on insulin-release from the clonal BRIN-BDll cell line. Upon purification of the skin secretions/extract, multiple insulin-releasing peptides were isolated and fully characterised by mass spectrometry along with N-terminal amino acid sequencing by Edman degradation. A number of synthetic peptides demonstrated potent in vitro biological activities, possessing the ability to stimulate insulin release up to a concentration of 3 flM without any association of cellular toxicity. For example, brevinin-2GUb isolated from the skin extract of H. guntheri stimulated insulin release 3.7 fold compared to 5.6 mmol/l glucose control (P
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Layne, Joseph D. Jr. « Novel insights into the function and regulation of group X secretory phospholipase A2 ». UKnowledge, 2013. http://uknowledge.uky.edu/nutrisci_etds/10.
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Group X secretory phospholipase A2 (GX sPLA2) hydrolyzes membrane phospholipids producing free fatty acids and lysophospholipids. Previous studies from our lab suggest that mice with targeted deletion of GX sPLA2 (GX KO) have increased age-related weight gain due to an increase in overall adiposity. Paradoxically, this increased adiposity is associated with improved age-related glucose intolerance. GX KO mice also demonstrate a reduced inflammatory response to lipopolysaccharide injection. In vitro studies indicate this phenotype may be attributable to blunted macrophage mediated inflammatory responses. Given the role of macrophages in promoting adipose tissue (AT) inflammation and metabolic dysfunction in response to diet-induced obesity, we hypothesized that GX KO mice would be protected from the obesity related metabolic derangements associated with overfeeding. Unexpectedly, GX KO mice were only partially protected from high fat (HFD) diet-induced glucose intolerance and showed no improvement in HFD-induced insulin resistance. Moreover, GX KO mice were not protected against HFD-induced AT inflammation.
GX sPLA2 is produced as a proenzyme (pro-GX sPLA2), and propeptide cleavage is required for enzymatic activity. Furin-like proprotein convertases (PCs) have recently been implicated in the proteolytic activation of pro-GX sPLA2; however the identity of individual PCs involved is unclear. Previous findings from our lab have shown that GX sPLA2 is expressed in the adrenals where it regulates glucocorticoid production. GX KO mice have increased plasma corticosterone levels under both basal and ACTH-induced stress conditions. However, how GX sPLA2 is regulated in the adrenals is still uncertain. We hypothesized that PCs may be involved in the proteolytic activation of pro-GX sPLA2 in the adrenals. Here we report the novel findings that the PCs, furin and PCSK6, proteolytically activate pro-GX sPLA2 in Y1 adrenal cells. Furthermore, we demonstrate that PC dependent processing of pro-GX sPLA2 is necessary for GX sPLA2 dependent suppression of steroidogenesis. Finally, we provide evidence that pro-GX sPLA2 processing by PCs is enhanced in response to adrenocorticotropic hormone (ACTH), suggesting a novel mechanism for negatively regulating adrenal steroidogenesis. Cumulatively, these studies provide valuable insight into the function and regulation of GX sPLA2.