Bryn Mawr Biologist Looks at Genetic Redundancy in Nature Article

Posted June 16th, 2010 at 3:18 pm.

greg-davisAssistant Professor of Biology Greg Davis is among the authors of the article "Phenotypic Robustness Conferred by Apparently Redundant Transcriptional Enhancers," which was recently published by the journal Nature.

Davis and the other researchers looked to see if changes in temperature had any effect on apparently redundant transcriptional enhancers involved in the embryonic development of fruit flies.

"Redundancy is something biologists have found a lot of as they better understand genetics," explains Davis. "Often times there will be more than one gene involved in the same process and then there are apparently redundant transcriptional enhancers, which are pieces of DNA that regulate a gene's expression.

"If you think of an organism as a building, you can think of development as the process of constructing that building.  At the construction site, the genes are like the cranes and other machinery. If one crane goes bad or is defective, it's good to have backup. The transcription enhancers would be like start buttons on each crane. Again, if one start button doesn't work, it's good to have another. This is the sort of redundancy we see in nature."

In looking at the development of fruit flies, the researchers found that under normal laboratory conditions at 25 degrees Celsius they could remove one of the apparently redundant enhancers from a fruit fly embryo and it would develop properly.

But once the researchers changed the temperature, making it either significantly hotter or colder, the removal of the apparently redundant enhancer would result in malformation, revealing that the enhancers were not, in fact, completely redundant.

"To go back to our metaphor, we found that if it gets really hot or really cold, you have to press both buttons to get that crane to do what it has to do," says Davis.

The researchers also looked at the role the redundant enhancers play in buffering the organism against genetic abnormalities.

"As long as all the other genes are perfectly fine, removing the enhancer doesn't appear to have any effect. But, if you mess around with some of the other genes, it turns out you do need both buttons," says Davis.

Princeton Biologists David Stern and Nicolas Frankel are the corresponding and lead authors on the paper, respectively. Davis worked with both as a research fellow prior to coming to Bryn Mawr in 2008.

Davis is currently studying the genetics of tiny insects called aphids, which can quickly adapt to their environments by altering their development.

"It's sort of the opposite of what this research was looking at," says Davis. "Redundancy is about guaranteeing the same traits get passed along in spite of environmental factors. Aphids exhibit phenotypic plasticity, which allows them to have these discrete differences in developmental outcomes. So aphids come in different forms—winged and wingless, for instance—depending on the environmental circumstances."

In the fall of 2010, Davis will be teaching "The Historical Role of Women in Genetics and Embryology" as part of the "Changing Education" group of courses tied to Bryn Mawr's 125th-anniversary celebration.

The course will examine the role that women scientists and technicians played in the development of genetics and embryology from the late-19th to the mid-20th century. The course will look at the work and lives of well-known and lesser-known individuals, asking how factors such as their educational experiences and mentor relationships played a role in their contributions. One facet of the course will focus on the Bryn Mawr biology department from the founding of the College into the mid-20th century.

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