Microorganisms are a goidmine for evolutionary genetics as their genomes can
evolve at an extraordinary rate which results in some of the most extravagant adaptations
in terms of genome structure and function as well as survival in the most unusual
environments. One trend observed in several evolutionary scenarios is genome
degeneration. It is most prominent in endosymbionts and obligate intracellular parasites
and is a consequence of many constraints encountered in the intracellular environment.
The process involves loss of many protein-coding genes, resulting in greater dependence
on the host, and loss of non-coding DNA such as intergenic regions, which has a direct
impact on regulation of genome function. I have chosen two evolutionarily distinct
systems to analyze the stages and functional consequences of genome degeneration,
namely the impact of genome compression on transcription in an obligate parasite
Antonospora locustae (genus Microsporidia), and gene content in the mitochondrion of a
diatom endosymbiont found in the dinoflagellate Durinskia baltica. I have successfully
mapped transcriptional start and termination sites from 14 loci in Antonospora locustae,
and cloned fragments of two genes that are part of the electron transport chain from the
mitochondrion of the diatom endosymbiont in Durinskia baltica. My analysis reveals
that transcription in A. locustae is always initiated immediately upstream of the open
reading frame at a single point for every locus, whereas transcriptional termination can
occur at several points for a single gene and, in some instances overlaps with a
downstream reading frame. The identification ofNADH5 and ATPase9 from the
mitochondrion of the endosymbiont in D. baltica is further evidence for the preservation
of function in this enigmatic organelle.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU./4086 |
| Date | 11 1900 |
| Creators | Gangaeva, Anna Evgenyevna |
| Publisher | University of British Columbia |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | 1081030 bytes, application/pdf |
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