Dokument: Evolution in the shadows of genome reduction - resolving molecular mechanisms and early branches in polyextremophilic Red Algae
| Titel: | Evolution in the shadows of genome reduction - resolving molecular mechanisms and early branches in polyextremophilic Red Algae | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=52549 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20200313-134749-2 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Rossoni, Alessandro [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Weber, Andreas [Gutachter] Prof. Dr. Feldbrügge, Michael [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 570 Biowissenschaften; Biologie | |||||||
| Beschreibung: | Molecular neofunctionalization through genome/gene duplication and expansion, exemplified by plants and animals, has long been believed to be the main driver of environmental adaptation. This notion is recently being challenged by free-living organisms with highly reduced genomes which exhibit a surprising adaptational capacity. But how can organisms with miniature genomes successfully adapt to changing environments? Here, we chose the Cyanidiales, a group of unicellular and polyextremophile red algae, as model organisms for studying the above-mentioned question due to their broad ecological boundaries in spite of highly streamlined genomes and miniature gene inventories.
An RNA expression analysis on cold stressed Galdieria sulphuraria provided evidence that spliceosomal complexity and intron richness constitute a potential mechanism to counteract the consequences of genome reduction and for generating functional diversity. Another boost to the adaptational ability may be through the acquisition of foreign genes via horizontal gene transfer (HGT). Through sequencing 10 novel Cyanidiales genomes we determined that 1% of their gene inventory is HGT-derived. Further, we provide the first explanation for the absence of a pangenome and cumulative effects in eukaryotes: HGT in eukaryotes is very rare and HGT genes have a stronger propensity to gene erosion. The presumption that eukaryotic HGT unfolds in the eukaryotic kingdom in the same manner that prokaryotic HGT unfolds in the prokaryotic kingdom is incorrect. Also, we characterized the – thus far – hypothesized involvement of HGT genes in stress adaptation through multiple experiments. Gene expression was measured using RNA-Sequencing in cold-stressed Galdieria sulphuraria 074W and “CO2-stressed” Cyanidioschyzon merolae 10D. In both cases, strong transcription of HGT genes was measured, providing evidence for the successful integration of HGT genes into the transcriptional machinery of the host. Furthermore, some interesting and unexpected acclimation strategies under cold stress were found and characterized, such as the upregulation of C1 metabolism, especially the S-adenosylmethionine cycle and folate cycle in Galdieria. Finally, we analyzed the effects of prolonged exposure to cold temperature upon the genetics and growth phenotype of Galdieria sulphuraria RT22 for a period spanning >100 generations. Long term selection towards temperature tolerance does not have a “master switch”. Rather, it constitutes a systems biology problem which requires the gradual orchestration of an intricate gene network and deeply nested regulators at a genetic and epigenetic level equally affecting native and HGT genes. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Biologie » Biochemie der Pflanzen | |||||||
| Dokument erstellt am: | 13.03.2020 | |||||||
| Dateien geändert am: | 13.03.2020 | |||||||
| Promotionsantrag am: | 25.07.2019 | |||||||
| Datum der Promotion: | 08.11.2019 |
