( A large clawed frog is helping Oregon ...)Clawed frog helps Fanconi anemia research make leaps

Scientists in the OHSU School of Medicine's Department of Biochemistry and Molecular Biology are the first to report a new approach using eggs of the African clawed frog, which goes by the Latin name Xenopus laevis, to understand how the Fanconi anemia proteins ensure that DNA is replicated properly, according to a study published this month in the journal Molecular and Cellular Biology.

The international team is led by the OHSU laboratory of Maureen Hoatlin, Ph.D. Using extracts from Xenopus eggs and chemically triggering DNA copying, the team showed that the Fanconi proteins function to prevent accumulation of breaks in DNA strands that arise even during normal replication. Fanconi anemia is thought to be the result of a defect in the Fanconi genes' ability to repair DNA damage.

Hoatlin said there are many advantages to using the frogs' eggs, instead of human cells, to study Fanconi anemia.

"In human cells, most of the Fanconi proteins are hard to detect, so you have to grow millions of cells over long periods of time to collect enough to study," she said. "The other problem is that cultured human cells are at all different stages of the cell cycle. The bulk of the cells are not rapidly dividing, and it's only when cells are dividing that the Fanconi proteins are usually at their highest expression and activity."

In Xenopus eggs, however, Fanconi proteins are stockpiled in preparation for the rapid divisions that occur after fertilization. Plus, the divisions occur at the same time, or synchronously, allowing naturally regulated stages of division to be studied simultaneously.

"It's very hard to synchronize mammalian cells," Hoatlin added. "Also, unfortunately for Fanconi researchers, methods used to synchronize cells are usually
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Source:Oregon Health & Science University