Scientists have studied Daphnia for centuries because of its importance in aquatic food webs and for its transformational responses to environmental stress.
Like the virgin nymph of Greek mythology that shares its name, Daphnia thrives in the absence of males--by clonal reproduction, until harsh environmental conditions favor the benefits of sex.
"More than one-third of Daphnia's genes are undocumented in any other organism--in other words, they are completely new to science," says Don Gilbert, paper co-author and scientist at IU Bloomington.
Sequenced genomes often contain some fraction of genes with unknown functions, even among the most well-studied genetic model species for biomedical research, such as the fruit fly Drosophila.
By using microarrays (containing millions of DNA strands affixed to microscope slides), experiments that subjected Daphnia to environmental stressors point to these unknown genes having ecologically significant functions.
"If such large fractions of genomes evolved to cope with environmental challenges, information from traditional model species used only in laboratory studies may be insufficient to discover the roles for a considerable number of animal genes," Colbourne said.
Daphnia is emerging as a model organism for a new field of science--environmental genomics--that aims to better understand how the environment and genes interact.
This includes a practical need to apply scientific developments from this field to managing our water resources and protecting human health from chemical pollutants in the environment.
James Klaunig, a scientist at IU Bloomington, predicts that the work will yield a more realistic and scientifically-based risk evaluation.
"Genome research on the responses of animals to stress has important implications for assessing environ
|Contact: Cheryl Dybas|
National Science Foundation