RESEARCH INTERESTS

Genome Evolution

A major mechanism that has shaped the genome of many organisms is gene duplications. As the number of completely sequenced genomes increases, the impact of gene duplications on their structure becomes obvious.

We are interested in the extend of gene duplications in a variety of organisms, the mechanisms that create gene duplicates as well as in the dynamics that lead to their preservation within genomes.

A major duplication event affecting the entire genome of the early vertebrates is one of the most discussed hypothesis.

Genome duplications at the origin of vertebrates

According to the 2R hypothesis, a large proportion of gene duplicates in vertebrate genomes are the result of at least one complete genome duplication event that occurred at the origin of vertebrates.

Most studies published so far testing the validity of the 2R hypothesis included a limited number of genes from organisms phylogenetically close to the point of the hypothesised genome duplications. In a recent publication (Panopoulou et al. (2003) New evidence for genome-wide duplications at the origin of vertebrates using an amphioxus (Branchiostoma floridae) gene set and completed animal genomes. Genome Research, 13 (6a), 1056-1065.) we evaluate the validity of the 2R hypothesis through an amphioxus gene catalogue. Our study is based on the comparison of the copy rates of amphioxus genes to their vertebrate (human-mouse) orthologs.

We have chosen amphioxus (Branchiostoma floridae species) for this comparison since amphioxus represents the closest chordate phylum to vertebrates, the cephalochordates. Therefore it is central for investigating the extent of gene duplications at the origin of vertebrates.

To be able to decide on the nature of the duplication event at the origin of vertebrates we have also assessed in the above publication, the arrangement of duplicated genes in the human genome in duplicated segments. Besides restricting our analysis on genes for which we can be fairly confident that were duplicated at the origin of vertebrates, we have imposed the additional criterion of these segments being also duplicated in the mouse genome before we decide which ones are the result of the duplication event at the origin of vertebrates rather than due to recent segmental duplications.

Gene Duplications across phyla

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