African clawed frog genome contains 2 full sets of chromosomes from 2 extinct ancestors
Millions of years ago, one species of frog diverged into two species. Millions of years later, the two frogs became one again, but with a few extra chromosomes due to whole genome duplication. Such is the curious case of the African clawed frog, Xenopus laevis, a frog whose genome contains nearly double the number of chromosomes as the related Western clawed frog, Xenopus tropicalis.
|Though similar in appearance, the tetraploid Xenopus laevis adult female is noticeably larger than its counterpart |
in the related diploid species Xenopus tropicalis [Credit: 2016 Shuji Takahashi]
Prof. Daniel Rokhsar, Professor of Genetics, Genomics and Development at the University of California, Berkeley and head of the Molecular Genetics Unit at the Okinawa Institute of Science and Technology Graduate University (OIST), Prof. Masanori Taira from the University of Tokyo and Prof. Richard M. Harland from the University of California at Berkeley led groups of researchers in examining the genome evolution of the African clawed frog. This large, collaborative project included scientists from a variety of universities and institutions across the globe. The study, published in Nature and featured on the cover, revealed that the X. laevis genome is composed of two different sets of chromosomes from two extinct ancestors.
Dr. Yuuri Yasuoka of the Marine Genomics Unit at OIST helped to manually correct the gene annotation. His graduate studies at the University of Tokyo under the guidance of Prof. Masanori Taira allowed him to develop the skills necessary for his role in this project. "Taking advantage of my experiences on the field of developmental biology, I examined genes involved in developmental processes," he clarified.
This large collaborative project resulted in new knowledge of genome duplication that can be applied to evolutionary studies of other organisms. "Because X. laevis is a well-studied model system for cell and developmental biology, it is ideal for to studying the effect of polyploidy on evolution," Dr. Simakov explains.
Source: Okinawa Institute of Science and Technology (OIST) Graduate University [October 19, 2016]