• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • No language data
  • Tagged with
  • 1
  • 1
  • 1
  • 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

Evolutionary analysis of animal microRNAs

Guerra Martins dos Santos Assunção, José Afonso January 2013 (has links)
In recent years, microRNAs (miRNAs) have been recognised as important genetic regulators of gene expression in Animals and Plants. They can potentially target a large fraction of the cellular transcriptome, having been shown to be important for diverse biological processes such as development, cell differentiation, proliferation and metabolism. The publication of the Human genome in 2001 marked the start of a great community effort to sequence a variety of other species. These data have great potential for comparative genomics, that can lead to better biological understanding. Some miRNA families are known to be highly conserved, across long evolutionary distances, many found in co-transcribed clusters across the genome. While these phenomena have been previously reported, a large-scale analysis of evolutionary patterns was still lacking. Furthermore, the rate at which new relevant data is being made available makes it challenging to keep up and many of the evolutionary studies performed before are now significantly out of date. This thesis describes a number of approaches taken to analyse miRNA datasets, harnessing the full potential of currently available data for comparative genomics. These were used, not only to revisit many of the notions in the field with a larger and updated dataset, but also to develop novel strategies that enable a coherent view of miRNA evolution at different evolutionary time-scales. A new tool, described within this thesis, was developed for large-scale, species independent miRNA mapping. An assessment of the evolution of the miRNA reper- toire across species was performed, together with detailed sequence conservation analysis and miRNA family clustering. Phylogenetic profile analysis uncovered in- teresting co-evolution between miRNAs and protein coding genes. The genomic organisation of miRNAs and their conservation across species was also studied, pro- viding detailed conserved synteny maps for miRNAs and proteins across more than 80 species. Finally, at the intra-specific level, I analysed the occurrence of single nucleotide polymorphisms affecting miRNA loci or their predicted target sites. All the tools built and integrated in this research were made available to the community and designed to be easily updated, making it easier to keep up with the data that is constantly being made available. Many aspects of miRNA biology are still being uncovered, and the ability to easily put these findings into an evolutionary context will potentially be useful for the community.

Page generated in 0.0913 seconds