"Genetic map created of tiny crustacean"

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By Steve Hinnefeld / from the Herald Times

Scientists from around the world gathered at Indiana University recently for a historic occasion: the completion of the first sequencing of the genome of a crustacean.

They’ve posted on Web sites the genetic map of the water flea, scientific name Daphnia pulex, making it available for other researchers to study. They plan to publish their findings near the end of this year.

“This is a huge endeavor,” said John Colbourne, the Daphnia project director at IU’s Center for Genomics and Bioinformatics. “It’s so far removed from anything else that’s been sequenced.”

But the true goal of the effort is even more far-reaching. The Daphnia Genomics Consortium hopes to use the crustacean to understand how organisms respond genetically to changes in their environment.

Colbourne envisions a future in which scientists can measure the biological effects of toxic chemicals, laying the groundwork for more effective regulations to protect human health and the environment...

...It brought together researchers from disparate branches of biology and beyond: not just genetics and genomics experts but ecologists, toxicologists, crustacean specialists and evolutionary biologists along with biochemists and bioinformaticists.

Daphnia makes sense for such work for a number of reasons, Colbourne said. The tiny creatures, less than a quarter-inch in length, have been studied by scientists since the 1600s. They are present in all sorts of freshwater ecosystems, from acidic and polluted ponds to pristine streams and lakes.

They occupy a pivotal position in food webs, feeding on algae, bacteria and protozoa while serving as forage for fish. And most importantly, they are known for genetically adapting to environmental stress.

“You’ll find Daphnia in the most saline lakes on the planet,” Colbourne said. “You’ll find Daphnia in alpine ponds and lakes that are bombarded with UV radiation. It can rapidly change with the changing environment.”

Finally, Daphnia, which reproduce both asexually and sexually, sometimes produce eggs that don’t hatch, go dormant and are preserved for up to 100 years in dried lake or river beds. Scientists can trace changes in the genotype and tie it to historic changes in the aquatic environment.

“It’s kind of like a time machine,” Colbourne said.