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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Analys av DNA-metylering i genen CREBBP och dess koppling till autism / Analysis of DNA-methylation in the Gene CREBBP and its Connection to Autism

Söderberg, Karolina, Fröjdman, Sofie January 2023 (has links)
Autism är en neuropsykiatrisk funktionsnedsättning som i olika utsträckning påverkar individens sätt att tänka, vara och kommunicera. Arv har visat sig vara en betydande faktor till varför vissa får autism, och forskning tyder på att det finns ett samband mellan autism och en obalans i metyleringsmönstret i vissa gener. Målet med arbetet var därav att för tre olika promotorer i genen CREBBP undersöka huruvida ett gemensamt metyleringsmönster för personer med autism kunde urskiljas. Därefter jämföra detta med metyleringsmönster i samma promotorregioner hos individer utan autism för att kunna dra slutsatser om ett tydligt samband mellan metyleringsmönster och autism finns. Avdelningen för sällsynta diagnoser på SciLifeLab försedde arbetet med helgenomsekvenseringsdata där flertalet individer hade avvikelser i gener som tros kan kopplas till autism. För att kartlägga metyleringsmönster utvecklades två Matlab-program. Det ena för att visualisera metyleringen i en gens promotorregion och den andra för att numeriskt jämföra två individers metyleringsmönster med varandra. Resultatet påvisade inget tydligt samband mellan autism och metyleringsmönster i de tre aktuella promotorerna i CREBBP och om ett liknande projekt skulle genomföras i framtiden finns det möjlighet för vidare utveckling. / Autism is a neuropsychiatric disability which in various extent affects the individual's way of thinking, being and communicate. It has been shown that heritage contributes to the development of autism, and science suggests there is a connection between autism and an imbalance in the methylation-pattern in specific genes in the DNA. The purpose of this study was to examine if a methylation pattern could be distinguished for individuals who had abnormalities in genes that are believed to be correlated with autism. This was examined in three promoter regions in the gene CREBBP. The result was then compared with the methylation pattern in the same region for individuals without autism to assess whether there is a difference between the two groups.  The department of rare diseases on SciLifeLab provided this project with sequencing data from the individuals. To find a methylation pattern, two Matlab programs were developed. One to visualize the methylation in a gene’s promotor region and the other to numerically compare two individuals' methylation patterns. The result did not show any clear connection between autism and the methylation in the different promotor regions. If a similar project would be carried out in the future, there is a possibility of further development.
2

Analysis of DNA methylation changes and behavioural outcomes in adulthood induced by prenatal exposure to a mixture of endocrine disrupting chemicals

Kamil, Shane January 2022 (has links)
Endocrine disrupting chemicals, or EDCs, are some of the most prevalent toxic chemicals found in the environment because of human activity and they have a variety of adverse effects on both humans and wildlife. A proposed mechanism through which EDCs can negatively affect an organism is via an epigenetic mechanism known as DNA methylation, which can affect the development of the organism with negative outcomes later in life. The aim of this project was to investigate the effect of a prenatal exposure to mixture of EDCs, called Mixture N1, and its adverse effects. Mixture N1 has in a previous study been detected in the first semester of mothers, and linked to language delay in the offspring in the SELMA cohort study. We investigated relationships with DNA methylation pattern changes in key genes with exposure, gene expression and behaviour in the adult brains of the exposed mice.  Our results showed correlative as well as linear relationships between methylation and different behavioural outcomes for target genes. One gene in particular - Nr3c1 - stood out among the results, having links to both stress and sociability. Specifically, DNA methylation of this gene correlates to active stress coping behaviours as well as sociability, but with no mediation component in these relationships. These results are promising for the use of methylation analysis as a biomarker of EDC mixture exposure, but more so as a predictor of negative behavioural outcomes later in life. More research could strengthen this use, and uncover the mechanism through which methylation alone might affect changes in behaviour.
3

Charge transfer states at polymer solar cell interfaces : Insights from atomic-scale modeling / Laddningsöverföringstillstånd vid polymersolcellsgränssnitt : Inblick från modellering i atomskala

Svensson, Rickard January 2022 (has links)
Organic solar cells (OSCs) based on non-fullerene acceptors (NFAs) have attracted a great deal of attention in recent years due to their rapidly increasing efficiency and enormous potential. In this work, the optical and electronic properties of systems containing the very promising non-fullerene acceptor PYT have been thoroughly studied with the use of the density functional theory (DFT) and the time-dependent density functional theory (TDDFT). By changing the electron linker from thiophene to furan and selenophene, respectively, the PYT was divided into three variants, each of which was studied independently. In addition, these three systems were combined with the donor PBDB-T to generate two distinct interface conformations. The properties studied in this work include the optimized geometries, HOMO-LUMO levels, UV-Vis spectra, frontier molecular orbitals (FMOs), natural transition orbitals (NTOs), density of states (DOS), dipole moments, open-circuit voltages, exciton binding energies, and local exciton (LE) and charge transfer (CT) energies. The calculations were performed in chlorobenzene solution utilizing the polarizable continuum model (PCM). It was discovered that PBDB-T/PY-Se exhibited remarkable flatness employing the π-π stacking conformation which corresponds well with the excellent D/A compatibility observed experimentally. All interfaces displayed appropriate positioning of the HOMO-LUMO levels, with the acceptor dominating the LUMO and the donor dominating the HOMO, with HOMO-LUMO gaps ranging between 1.34 and 1.38 eV. The differences in the interchanging of the electron linker were not that significant, and neither was the change in interface conformation in terms of the HOMO-LUMO levels. This may indicate that the system can be effective even without the presence of a π-π stacking conformation. The first excited states for all interface systems were shown to be pure CT transitions, and on average, 80% of the states exhibit CT character. The remaining contributions consisted of transitions within the pure materials, with a larger contribution within the acceptor. The theoretical results of this study indicate that systems containing the novel polymer acceptor PYT and its variants PY-O and PY-Se exhibit very intriguing properties, and further development of OSCs containing these polymers might further aid in the development of high-performance OSCs. / Organiska solceller (OSC) baserade på icke-fullerenacceptorer (NFA) har väckt stor uppmärksamhet de senaste åren på grund av dess snabbt ökande effektivitet och enorma potential. I detta arbete har de optiska och elektroniska egenskaperna hos system innehållande den mycket lovande icke-fullerenacceptorn PYT studerats grundligt med användning av täthetsfunktionalteorin (DFT) och den tidsberoende täthetsfunktionalteorin (TDDFT). Genom att ändra elektronförbindelsen från tiofen till furan respektive selenofen så delades PYT upp i tre varianter som var och en studerades oberoende av varandra. Dessutom kombinerades dessa tre system med donatorn PBDB-T för att generera två distinkta gränssnittskonformationer. Egenskaperna som studeras i detta arbete inkluderar optimerade geometrier, HOMO-LUMO-nivåer, UV-vis spektra, gränsmolekylära orbitaler (FMO), naturliga övergångsorbitaler (NTO), tillståndstäthet (DOS), dipolmoment, tomgångsspänning, excitonbindningsenergi samt lokal exciton (LE) och laddningsöverförings (CT) energier. Beräkningarna utfördes i klorbensenlösning med användning av den polariserbara kontinuummodellen (PCM). I resultatet uppvisade PBDB-T/PY-Se en anmärkningsvärd planhet med användning av π-π staplingskonformationen som överensstämmer väl med den utmärkta D/A-kompatibiliteten som observerats experimentellt. Alla gränssnitt visade lämplig positionering av HOMO-LUMO-nivåerna, med acceptorn som dominerade LUMO och donatorn som dominerade HOMO, med HOMO-LUMO-gap mellan 1.34 och 1.38 eV. Skillnaderna i utbytet av elektronförbindelsen visade sig inte vara signifikanta och inte heller skillnaden i gränssnittskonformation när det gäller HOMO-LUMO-nivåerna. Detta kan indikera att systemet kan vara effektivt även utan förekomst av π-π staplingskonformation. De första exciterade tillstånden för alla gränssnittssystem visade sig vara rena CT-övergångar och i genomsnitt uppvisade 80% av tillstånden CT-karaktär. Resterande andel bestod av övergångar inom de rena materialen med en större andel inom acceptorn. De teoretiska resultaten av denna studie indikerar att system innehållande den nya polymeracceptorn PYT och dess varianter PY-O och PY-Se uppvisar mycket spännande egenskaper samt att vidareutveckling av OSC:er som innehåller dessa polymerer ytterligare kan hjälpa till i utvecklingen av högpresterande OSC:er.

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