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U. graduate student discovers method to detect developmental disorders in embryos


Alenna Patel, a graduate student in the chemical and biological engineering department, was the first author of this paper. 

Photo Credit: Department of Chemical and Biological Engineering 

University researchers proposed a new tool for researching cell signaling and regulation in developing embryos in a study published on Dec. 3 in Proceedings of the National Academy of Sciences.

Aleena Patel, a chemical and biological engineering graduate student, was the paper’s first author. In an experiment co-led by University professors Stanislav Shvartsman GS ’99 and Rebecca Burdine, Patel discovered a way to harness the power of cancer-related mutations to amplify the activation of light-sensitive enzymes during embryonic development. This technique could allow scientists to more precisely understand developmental regulation and its associated defects.


Embryonic growth is controlled by a network of highly regulated interactions between proteins. These interactions dictate which parts of an embryo will develop into which structures in the adult organism. The exact process by which this communication occurs is a central object of study in current molecular biology research.

“We, as developmental biologists, are interested in understanding how something that is as simple as a single cell can, in a relatively short amount of time, become something as complicated as a fully developed organism,” Patel explained.

The researchers chose to study one piece of this network that is common to almost all organisms: the extracellular receptor kinase (ERK) pathway. If protein interactions do not occur in the right pattern during development, the ERK pathway can cause mutations throughout the embryo that are associated with a whole class of developmental defects.

“There’s a lot of work we’re doing to try to understand where these mutations are coming from,” Patel said.

To study the role of the ERK pathway during development, the researchers used light to activate an enzyme unique to this pathway at different times and for different time intervals. This light-activation technique has been used in other studies and produced significant results, but Patel encountered a problem when applying it to the zebrafish embryo: the activation effect was not strong enough to study.

Patel’s novel response to this issue was to use mutated forms of this enzyme that can cause very prominent effects, even cancer, in zebrafish. These mutations made the light-sensitive molecule more powerful and its light-based activation more effective.


“You can think of it in two ways,” Patel clarified. “You can think of it as ‘We used the cancer mutation to optimize this tool’ … or you can think of it as ‘We used a new technology to harness the effects of a very misbehaved molecule.’” 

Patel’s method was successful not only in zebrafish, but in fruit flies as well. This suggests that the technique can be applied to study both invertebrate and vertebrate systems.

According to Burdine, using mutations to control light-sensitive enzyme activity is “a new concept” in the field of developmental biology. Patel’s technique will allow scientists to map ERK pathway signals and their effects during early and late stages of development, even down to the minute. This mapping may provide significant insight into the causes of developmental diseases and defects.

“We can think of everything that’s happening in embryogenesis as a domino effect,” Patel described. “Having the ability to tip those dominoes with light gives us much better, precise control over this whole entire network.”

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Patel emphasized that two undergraduates, Andrew Wu ’21 and Sarah McGuire ’18, worked in the lab as well, the latter using the research for her senior thesis. She also praised the experiment as “a nice example of collaboration between departments” that is possible at Princeton, as it drew researchers and resources from both molecular biology and chemical engineering. In fact, although the study is a contribution to developmental biology, Patel admitted that this was not her original field of study.

“I feel like I’ve done important things in developmental biology, even though I knew very little about it when I first came,” she remarked. “It’s nice to know that you can start at humble beginnings.”