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Pritham helps map DNA code of crustacean for first time

Ellen Pritham
Ellen Pritham

Assistant biology professor Ellen Pritham and her team have helped precisely map the DNA code of the water flea, Daphnia pulex, the first crustacean genome to be sequenced.

Daphnia emerges as a model organism for a new field - environmental genomics. Researchers in the field aim to better understand how genes and the environment interact. Their work includes building research tools for investigating the molecular underpinnings of key ecological and evolutionary problems.

Pritham said the genome holds some big surprises. More genes were found in the Daphnia pulex genome than any other animal ever sequenced. The Daphnia genome has about 31,000 genes compared to about 20,000 in humans.

Pritham's work with an international team is reported this month's edition of Sciencemagazine in an article called "The Ecoresponsive Genome of Daphnia pulex." Researchers hypothesized that many of the new genes are involved in Daphnia's intimate relationship with its environment and allow the organism to respond to a changing environment.

"The genome is the recipe book for building an organism," Pritham said. "Decoding the genome of a species is the first step to understanding what it takes to build that species and to see what components are the same and which are different... Interestingly, despite Daphnia being more closely related to insects, it shares more genes in common with humans." Pritham's lab was part of the transposable element annotation team. Transposable elements are genomic parasites. They are mobile pieces of DNA in the genome that do no benefit to the organism.

"The organism can't get rid of them," Pritham said. "Transposable elements frequently make up the largest proportion of an organism's genome. Therefore, once a genome has been sequenced it is critical that the transposable elements are annotated. The precise mapping of the transposable elements allows the genes to be annotated properly."

Pamela Jansma, dean of UT Arlington's College of Science, described Pritham's work as groundbreaking.

"It exemplifies the type of research that we do in the College of Science," Jansma said. "Exciting discoveries occur at the boundaries of disciplines where new fields, such as environmental genomics, are created. Understanding how organisms evolve and adapt to environmental change is a fundamental challenge."

The research also has been featured in Nature magazine.