The Language of Life: How Cells Communicate in Health and Disease. Debra Niehoff. Joseph Henry Press, Washington, DC, 2005. 309 pp., illus. $27.95 (ISBN 0309089891 cloth).
The purpose of The Language of Life is to summarize knowledge and present the most recent findings on cellular signaling mechanisms at the cellular and organ levels. Clearly, Debra Niehoff has read a great deal and talked to scientists who work on the subjects she covers, and her qualifications for writing about cellular communication would seem impressive: She trained as a neurobiologist at the Johns Hopkins University School of Medicine, and worked as a research scientist in both academic and industrial settings. Niehoff has also written several publications about the life sciences. However, she didn't perform any of the research she describes.
The Language of Life covers a vast amount of material. A brief description of the chapter topics alone conveys the book's wide scope.
The first chapter, about chemotaxis, starts with an account of the reactions involved in the movement of the E. coli flagellum, and details how it changes direction in the presence of a toxic stimulus or, alternatively, goes straight ahead toward a source of food. Three-dimensional drawings, here and throughout the book, nicely complement the text. (Also helpful throughout the book is the thorough index, which includes textbooks and other research literature on the topics Neihoff describes, up to 2002.)
Chapter 2 gives an account of the discovery of hormones. Niehoff explains how a signal such as adrenaline becomes bound to its receptor, ß-adrenergic receptor, which is a most complicated process that was unraveled by a number of scientists who were eventually able to combine their different findings to make a coherent story.
Chapter 3 moves to embryology, where the reader is introduced to the three requirements of a developing embryo: (1) a sense of direction, or polarity, illustrated by the fruit fly embryo; (2) the separation of inside from outside, with the hydra embryo and the frog egg as an example of a metazoan; and (3) compartmentalization, wherein compartments subdivide again and again in processes controlled by “hedgehog,” a signaling protein, and other complementary signalers. Readers also learn about gene expression in different locations—how genes controlling eye formation, for example, are switched on in the right place and at the right time—and about the development of the nervous system and how a cell may, or may not, develop into a neuron.
Chapter 4 covers homeostasis in health and in disease. Again readers encounter the hedgehog signaling protein: Lambs feeding on the corn lily are born with a single monstrous eye because a toxin in the plant interferes with the cells' ability to respond to hedgehog, which is suppressed. The same chapter includes a description of the genetic basis of cancer, diabetes, and obesity, all examples of diseases in which the body's homeostatic mechanisms have gone wrong.
Chapter 5 tackles the nervous system, beginning with Ramón y Cajal and his histological studies of the brain and moving on to the transmission of messages across synapses and an explanation of how a growing axon meets its target sense organ. This chapter contains a fascinating account of the neurobiology of learning and memory both in Aplysia and in the mammalian brain. Even in the former there is short-term and long-term memory; in mammals, the major memory organ appears to be the hippocampus, with another body, the amygdala, situated on top and acting to associate emotions with the memory tracks from the hippocampus.
Also of note in this chapter is an account of the immune system, which turns out to comprise three systems: One is innate, one adaptive, and the third dependent on dendrites (cells with a number of outgrowths). Adaptive immunity is dependent on lymphocytes covered with antigen receptors possessing the ability to distinguish between millions of bacterial and viral features. Dendrites and T-lymphocytes communicate through an “immunological synapse” comparable in important ways with the neural synapse, which may be the rationale for including the nervous and immunological systems in the same chapter.
The concluding chapter is an account of an annual meeting of the Alliance for Cellular Signaling, “a consortium of investigators with a common interest in the language of life.”
Interwoven with this copious material are anecdotes from Niehoff's family life. Jenny and Haley, her teenage daughters, are apparently quite a handful to manage. I was trying to learn about cell signaling, however, and I found the family lore distracting. Eventually, when her daughters' witticisms or comments on their appetite for Pop-Tarts interrupted rather dense scientific arguments, well loaded with acronyms, I became fully exasperated. Nonetheless, Niehoff uses two examples from her life to good effect. In the first, she describes the physiological results of a near car crash she suffered, which is entirely relevant to an explanation of the homeostatic mechanisms the body uses to overcome shock. The second useful example deals with the terrifying experience of riding a runaway horse, and explains why she was unable to overcome her fear: Unpleasant memories are hard to eliminate. On the whole, though, the personal anecdote as literary device fails to captivate.
Unfortunately, Niehoff does not appear to understand the properties of metaphors, the other device she employs throughout the book. She equates cell signaling with a language, and in the widest sense, perhaps it is. But it is not a language in the sense that English and French are languages. Language is simply a metaphor in this case, one that she stretches too far, claiming to find equivalents for words and sentences among the chains of chemical reactions. The two major features of human language are its syntax, and the fact that young children can use the rules of syntax to create new sentences, without having been specifically taught those rules. Woe to the biologist who uses the rules of biology to create new facts!
According to Niehoff, cells inform, wheedle, exhort, reassure, nurture, criticize, and instruct. Elsewhere, platelets shout “You there!” at fibroblasts (p. 144); cells “coo” and “bellow.” I find such expressions merely distracting, not elucidative. What am I to infer from them?
Architecture is the other metaphor Niehoff uses for cell design and structure, with more success. This analogy works better than the one with language because both cells and buildings have to deal with the effects of mass and force.
Students preparing for their doctoral exams will find the book useful for its breadth of coverage. The layman interested in cell signaling is advised to persevere. Harassed women scientists with unruly teenage daughters may well sympathize with the author, who, I think, should decide whether she intends to write novels or write about science and medicine.
