In a paper appearing on line this week ahead of regular publication in the Proceedings of the National Academy of Sciences, researchers report the sequencing and analysis of 27,161 expressed sequence tags (ESTs) of the sexually reproducing strain of the planarian Schmidtea mediterranea.

Not only were 66 percent of them similar to sequences already in public databases, the researchers found 142 of 287 genes associated with human diseases. Because the ESTs they studied represent only about one-half of the total, "it seems likely that the vast majority of human disease genes will have homologues in planarians," the scientists wrote.

"One of the striking things we found is that when we look at planarian genes, we see a group that is conserved between planarians and mammals that is not found in Drosophila or C. elegans," said Phillip A. Newmark, a professor of cell and developmental biology at Illinois. "We speculate that these conserved sequences may play roles in processes such as long-term tissue maintenance and cell turnover that are likely less important for short-lived organisms like nematodes and insects," wrote Newmark and colleagues.

Drosophila melanogaster and C. elegans (Caenorhabditis elegans) are standard model invertebrates used in biology. "The fact that they don't have some of the genes that planarians share with mammals says that planarians will be an important, complementary model for studying gene function," Newmark said.

On a more basic level, the work by Newmark and colleagues will aid the planarian genome-sequencing project being done at Washington University in St. Louis.

ESTs are short sequences of DNA pro
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Contact: Jim Barlow, Life Sciences Editor
jebarlow@uiuc.edu
217-333-5802
University of Illinois at Urbana-Champaign
13-Dec-2005