by Miwa Suzuki
Thu Sep 27, 2:54 PM ET
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, or Rena 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.
