An international team of researchers have decoded the genetic sequence of the African clawed frog, an important model system for cell and developmental biology, and immunology.
The study, published in the journal Nature, shows the peculiar animal arose from an ancient hybridisation event that combined the genomes of two different frog species 18 million years.
The researchers were able to investigate the hybridisation event by looking at special “jumping” genes, called transposons, which are located within the genomes. The study revealed that the frog, arose from interspecific hybridization – the mating of two species from within the same genus. The result is a “duplicated” genome, whereby the frog carries genetic material from two species.
Interestingly, certain portions of the “duplicated” genome appear to be evolving at different rates.
Australian researchers Dr Ozren Bogdanovic and Professor Ryan Lister from The University of Western Australia, the ARC Centre of Excellence in Plant Energy Biology and the Harry Perkins Institute of Medical Research collaborated on the international project.
“Genome duplication is a really important event in evolution, because it generates extra copies of all the genes and control sequences in the genome.” Professor Lister said.
“Through mutation of these extra copies, new molecular activities or patterns of gene use in the organism can arise, creating new functions that are important for evolutionary diversification”.
The two Australian researchers contributed to the project by mapping the frog’s epigenome.
“We mapped the precise genomic locations of an important biochemical signal, called DNA methylation, in the frog genome” said Dr. Bogdanovic.
“DNA methylation can be thought of as tiny chemical signposts that cells add to their genome. It has the ability to switch genes “on” and “off” during embryo development and disease formation.”
The study shows that DNA methylation played one of the most important roles in fine-tuning the levels of gene products making sure that proteins are produced at the correct levels despite the duplication of the genome sequence.
“This is a very important step towards our understanding of how genomes evolve and how genetics and epigenetics shape life on earth.” Dr. Bogdanovic said.
“The work also emphasises the importance of international collaboration and basic research on more “exotic” model organisms such as frogs or fish, as compared to mice and rats.”
The international collaboration included researchers from the United States, Japan, Korea, the Netherlands, Australia, and Switzerland, and was led by Daniel Rokhsar and Richard Harland of the University of California, Berkeley, and Masanori Taira of the University of Tokyo.