A team of scientists led by the Department of Energy's Joint Genome Institute (JGI) and the University of California, Berkeley, is publishing this week the first genome sequence of an amphibian, the African clawed frog Xenopus tropicalis, filling in a major gap among the vertebrates sequenced to date.
"A lot of furry animals have been sequenced, but far fewer other vertebrates," said co-author Richard Harland, UC Berkeley professor of molecular and cell biology. "Having a complete catalog of the genes in Xenopus, along with those of humans, rats, mice and chickens, will help us reassemble the full complement of ancestral vertebrate genes."
The high-quality draft sequence of the genome of X. tropicalis, often called the Western clawed frog, will also aid researchers who now use the frog's more popular cousin, Xenopus laevis (zen'-uh-pus lay'-uh-vus), to study embryo development and cell biology. X. laevis, with its large and easily manipulated eggs, has told scientists a lot about how a fertilized egg develops into an embryo, including how embryos set up front-back and head-tail axes. The genome of tropicalis will help scientists connect genetic changes with developmental milestones in both species, Harland said.
"Xenopus has been among the last model organisms to be sequenced," after the mouse, chicken, nematode, zebrafish and fruit fly, he said. "It will be tremendous to have a high quality sequence of X. tropicalis upon which to build the X. laevis sequence."
"The availability of the Xenopus genome also opens up the possibility of studying the effect of endocrine disruptors at the molecular and genomic level," added first author Uffe Hellsten, a bioinformaticist at the JGI. These chemicals mimic frogs' own hormones, and their presence in lakes and streams may be partly responsible for the decline of frog populations worldwide.
"Hopefully," he added, "understanding t
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University of California - Berkeley