Numerous data indicated that families of mobile elements have gradually accumulated in time to constitute a large fraction of the vertebrate DNA, shaping either genes or the whole genome. Rolling-circle eukaryotic trasposons, known as Helitrons, are widely distributed, from protist to mammal species. Autonomous Helitrons show a peculiar open reading frame, encoding for a polypeptide that contains typical domains for the rolling circle replication: the Rep (rolling-circle replication initiatior) and the DNA helicase domains. These elements are believed to have an important role in the evolution of the host genomes, owing to their frequent capture of host genes, some of which can evolve into novel genes or become essential for Helitron transposition. Actually, Teleost fishes are receiving an increasing attention as models for studying the evolutionary impact of the mobile DNA in vertebrates, since their genomes contain many families of mobile elements perhaps involved in the high biological diversity of these species. In this work, we performed a molecular analysis on the suborder of the Notothenioidei, a Perciformes group of species that nowadays dominate the Antarctic waters, due to their remarkable ability in achieving cold-adaptation. We isolated and characterized a strongly conserved Helitron element, that we named HeliNoto (8.9 kb), from the genome of the icefish species Chionodraco hamatus, belonging to the Channichthyidae, the most derived family of the Notothenioids. The unique open reading frame obtained was analysed and compared to homologous sequences present in the genome of different species. The distribution of these elements among Notothenioids was finally discussed.
Helitron transposons in the genome of Antarctic fish.
E Cocca;
2009
Abstract
Numerous data indicated that families of mobile elements have gradually accumulated in time to constitute a large fraction of the vertebrate DNA, shaping either genes or the whole genome. Rolling-circle eukaryotic trasposons, known as Helitrons, are widely distributed, from protist to mammal species. Autonomous Helitrons show a peculiar open reading frame, encoding for a polypeptide that contains typical domains for the rolling circle replication: the Rep (rolling-circle replication initiatior) and the DNA helicase domains. These elements are believed to have an important role in the evolution of the host genomes, owing to their frequent capture of host genes, some of which can evolve into novel genes or become essential for Helitron transposition. Actually, Teleost fishes are receiving an increasing attention as models for studying the evolutionary impact of the mobile DNA in vertebrates, since their genomes contain many families of mobile elements perhaps involved in the high biological diversity of these species. In this work, we performed a molecular analysis on the suborder of the Notothenioidei, a Perciformes group of species that nowadays dominate the Antarctic waters, due to their remarkable ability in achieving cold-adaptation. We isolated and characterized a strongly conserved Helitron element, that we named HeliNoto (8.9 kb), from the genome of the icefish species Chionodraco hamatus, belonging to the Channichthyidae, the most derived family of the Notothenioids. The unique open reading frame obtained was analysed and compared to homologous sequences present in the genome of different species. The distribution of these elements among Notothenioids was finally discussed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
