Arabidopsis to Zebrafish: A Commentary on "Rosetta Stone" Model Systems in the Biological Sciences

ARABIDOPSIS TO ZEBRAFISH: A COMMENTARY ON "ROSETTA STONE" MODEL SYSTEMS IN THE BIOLOGICAL SCIENCES HOWARD GEST* The Rosetta Stone was discovered by a French Officer of Engineers in July 1799, near the town of Rashid, also known as Rosetta, Egypt. Inscribed on the slab of black basalt were three scripts of the same text, in Egyptian hieroglyphics, Egyptian popular script, and Greek. The importance of the stone for understanding Egyptian hieroglyphics was immediately apparent. Through comparisons of the scripts, which turned out to have many complexities, the hieroglyphics were eventually deciphered, primarily through the efforts of the English polymath physician -physicist-natural philosopher Thomas Young (1773-1829) and the French scholar Jean François Champollion (1790-1832). The Rosetta Stone, now in the British Museum, is physically a dramatic object and was the key to decoding the ancient hieroglyphics. By the end of the 20th century, the term "Rosetta Stone" came into popular use to mean something, essentially anything, that acts as a "key" to "some previously unattainable understanding." A recent advertisement in a scientific journal shows a photograph of the Rosetta stone and proclaims that "Company X" sells a computer package that "provides you with the key to discovering information in a language even older than hieroglyphics: DNA, the language of life." Out understanding of cell growth and multiplication increased enormously during the first half of this century, but many basic aspects are still wrapped in mystery. During the past two decades, a new phenomenon has appeared in the pursuit of explaining biological mechanisms: namely, the proliferation of groups of investigators that have found it profitable to promote a particular biological species as a "Rosetta Stone"—that is, a species purported to be the experimental key for *Department of Biology and Department of History and Philosophy of Science, Indiana University, Bloomington, Indiana 47405.© 1995 by The University of Chicago. All rights reserved. 003 1 -5982/95/3804-0924$0 1 .00 Perspectives in Biology andMedicine, 39, 1 ¦ Autumn 1995 | 77 elucidating the details of a basic process used by all animals, plants, or microorganisms. Comparative Biochemistry The idea that the chemical activities of cells of different kinds show both common as well as grossly divergent features is old, and was emphasized by Pasteur in his pioneering research on the causes of fermentations . Ruminations on this theme permeated early investigations on the enzymatic steps of glycolysis and on alcoholic fermentation, and from Meyerhof's monograph of 1924, one can recapture the unexpected first realizations that glucose catabolism by muscle and yeast cells occurs through an almost identical series of reactions [I]. Attempts to formalize comparative biochemical principles during the late 1920s led to a psychological "pandemic" of "overly comparative biochemistry." This affected biologists and biochemists in several ways. Some became biochemically blurred and unable to clearly perceive the significance of interesting differences in the overall metabolic patterns of very different physiological types of organisms. An extreme symptom of the "disease" was the view that most metabolic processes are intrinsically similar, consisting of series of reactions which could be generally represented by the equation: AH2 + B^ BH2 + A This was a basic "philosophy" presented by C. B. van Niel in his famous summer course on microbiology, which I took as a graduate student in 1947. At the time, some investigators saw metabolic differences in somewhat sharper focus, while others, with "mild infections," vacillated somewhere in-between. It has been evident for some time that biological scientists interested in comparative biochemistry fall into two philosophical groups roughly comparable to the "lumpers" and "splitters" in polemical arguments on taxonomy. Krebs and Romberg put it this way: Discussions have taken place from time to time about the "unity" or "disunity" of the biochemical organization of different types of organism. Some authors consider it as more profitable to emphasise different rather than common features . Thus [S. S.] Cohen suggests that comparative biochemistry should concern itself with "the study of the origin, nature and control ofbiochemical variability." On the other hand, Stanier, following Kluyver and van Niel, defines the task of the comparative biochemists as "to seek for the common biochemical principles which are expressed in all forms of life." These differences merely reflect different attitudes...