SEE-THROUGH SALIENTIA

NEWS RELEASE
The Center for North American Herpetology
Lawrence, Kansas
http://www.cnah.org
4 October 2007

SEE-THROUGH SALIENTIA

Miwa Suzuki
27 September 2007

TOKYO (AFP) - Japanese researchers have succeeded in producing see-through frogs,
letting them observe organs, blood vessels and eggs under the skin without performing
dissections.

"You can see through the skin how organs grow, how cancer starts and develops," said the
lead researcher Masayuki Sumida, professor at the Institute for Amphibian Biology of
state-run Hiroshima University.

"You can watch organs of the same frog over its entire life as you don't have to dissect it.
The researcher can also observe how toxins affect bones, livers and other organs at lower
costs," he told AFP.

Dissections have become increasingly controversial in much of the world, particularly in
schools where animal rights activists have pressed for humane alternatives such as using
computer simulations. Sumida said his team, which announced the research last week at
an academic conference, had created the first transparent four-legged creature, although
some small fish are also see-through. The researchers produced the creature from rare
mutants of the Japanese brown frog (Rana japonica), whose backs are usually ochre or
brown. Two kinds of recessive genes have been known to cause the frog to be pale.

Sumida's team crossed two frogs with recessive genes through artificial insemination and
the offspring looked normal due to the presence of more powerful genes. But crossing the
offspring led to a frog whose skin is transparent from the tadpole stage.

"You can see dramatic changes of organs when tadpoles mutate into frogs," said Sumida,
whose team is seeking a patent.

Such frogs could theoretically exist in the wild but it is "virtually impossible" they would
naturally inherit so many recessive genes, Sumida said. The transparent frogs can also
reproduce, with their offspring inheriting their parents' traits, but their grandchildren die
shortly after birth.

"As they have two sets of recessive genes, something wrong must kick in and kill them,"
Sumida said.

While the researchers relied on artificial insemination, they said that genetic engineering
could also produce transparent and even illuminating frogs. Sumida said researchers could
also inject into the transparent frogs an illuminating protein attached to a gene, which
would light up the gene once it manifests -- for example, showing at what stage cancer
starts. Sumida said it would be unrealistic to apply the same method to mammals such as
mice as their skin structure is different.