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The personal and professional collide in a scientist’s story of early human development

The Dance of Life: The New Science of How a Single Cell Becomes a Human Being

Magdalena Zernicka-Goetz and Roger Highfield
Basic Books
2020
304 pp.
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With one phone call, Magdalena Zernicka-Goetz’s life as a scientist collided with her personal life in the most dramatic way. As Zernicka-Goetz stood at her desk at the University of Cambridge, a genetic counselor explained that some cells derived from the placenta supporting her fetus carried a serious chromosomal anomaly. But her knowledge of how embryos develop suggested that the fetus might be able to exclude the cells with the genetic abnormality or that it may not contain the damaged DNA at all. Further testing confirmed that the fetus was genetically normal, and her son was born in perfect health. “At the time,” however, she writes, “I couldn’t possibly be sure.”

In The Dance of Life, Zernicka-Goetz and science writer Roger Highfield weave Zernicka-Goetz’s personal memoir together with an accessible introduction to contemporary mouse and human embryonic research and with a discussion of the clinical, ethical, and societal implications of this research and related areas. This is a lofty goal for a relatively slim volume, and it succeeds better in some parts than in others.

Developmental biologists have studied the progression of the fertilized mammalian egg through its early cleavage divisions to the formation of the 100-cell blastocyst for many years. Such studies have suggested that there is a gradual segregation of cell fate influenced by cell polarity, cell position (inside or outside), and mechanical signals and that the embryo is able to regulate for loss, gain, or rearrangement of cells right up to the blastocyst stage. However, none of these studies really addressed the question of whether there might be asymmetries in the egg or early embryo that could bias later cell fate.

Zernicka-Goetz, who has long been fascinated with patterning in the early embryo, took on this challenge when she began her own research lab at the University of Cambridge. She describes her work on defining early asymmetries in the mouse embryo and their role in informing later development in careful detail, recounting how she used tools such as cell marking, live imaging, and gene manipulation to determine that early blastomeres show a bias toward different regions and cell types of the blastocyst. However, other researchers—using different techniques—found less evidence for early differences, leading to some vigorous debates, as described in the book.

This controversy compelled researchers who had set aside work on the early embryo to reenter the fray, bringing new tools and ideas. And, although it is still not clear what initiates asymmetries after fertilization, it is increasingly clear that by the four-cell stage, there are differences in chromatin modification and transcription factor activity among the cells that, while not permanently specifying cell fate, may bias their future lineage contributions.

The book does not shy away from discussing the moral and ethical implications inherent in such research, tackling prenatal testing, the ongoing quest to create synthetic embryos, and the question of whether human embryos should be used in research. “Although an early embryo is not a person, I believe that it deserves protection, and I fully appreciate that balancing that protection with scientific research is not easy,” writes Zernicka-Goetz of the latter issue. Her attitude has been to tread carefully, weighing potential concerns against potential value to humanity. “I believe in taking a measured approach to enable research that is fully consistent with our values.”

The authors do their best to describe experiments on the early embryo and stem cell–based embryo models in simple terms, but the book would have been greatly enhanced by the inclusion of some illustrations. The early embryo is truly beautiful, especially when the complexity of gene expression patterns is revealed by fluorescent imaging. Also, some of the science may be hard for the uninitiated to follow. In the fifth chapter, for example, the embryonic cleavage divisions from one cell to four cells are described using a two-tone soccer ball analogy. This takes two full paragraphs to explain a concept that could have been easily conveyed with a simple diagram.

The most engaging parts of The Dance of Life are the personal stories about the trials and tribulations Zernicka-Goetz has faced during her life in science. Scientific disagreements occur, papers get rejected, grants are not funded, and balancing family and work is never easy. Those of us who, like Zernicka-Goetz, are developmental biologists are in the fortunate position of being in a field where many leading scientists are women (no all-male panels for us!), but female scientists still struggle to overcome the persistent biases and societal and institutional barriers that block their progress. At the end of the day however—as Zernicka-Goetz and Highfield so ably show—the thrill of scientific discovery is what keeps us coming back to the bench.

About the author

The reviewer is president and scientific director of the Gairdner Foundation, Toronto, ON M5G 1L7, Canada, and a senior scientist at the Hospital for Sick Children, University of Toronto, Toronto, ON M5G 0A4, Canada.