Perspectives in Biology and Medicine

HOW EMBRYOLOGISTS BECAME DEVELOPMENTAL BIOLOGISTS ANDOTHER MATTERS DONALD D. BROWN* If the Hominunculus was the seventeenth century's concept of a sperm, then the phage was surely the twentieth century's version. Much of the last 20 years has been devoted to disproving this model. At the first embryology meeting I attended, a molecular biologist describing fertilization said that the sperm attached itself to the egg by its tail. In the ensuing years, one of the most exciting discoveries has been that gene organization and the regulation of gene expression in eukaryotes differ from those in prokaryotes. The history of embryology and its change into developmental biology are instructive for anyone who cares about scientific progress. Embryology is a problem, a set of questions, not a discipline. It is like cancer or cystic fibrosis and unlike mathematics, physics, chemistry, genetics, and biochemistry. The problems yield and the field evolves each time a new method or principle is discovered in one of the allied disciplines. The progression is so obvious that it is possible to advise a young scientist to study the disciplines and then apply these new principles and methods to important but ignored questions in biology. Such new applications, as well as scientific collaboration across national boundaries, are essential to the advancement of science. The earliest embryologists, such as Morgan and Boveri, were great geneticists. Boveri rediscovered Mendel and showed that each chromosome is different; he discovered the first true mechanism of eukaryotic gene expression, chromosome diminution. The next generation of embryologists were called "experimental embryologists ." They studied animals unsuited for traditional genetics because of their long life cycle and complexity. Experimental embryology did not, however, flourish, because it was treated as a discipline rather than as a set of questions. Next came biochemical embryology, in which *Director, Department of Embryology, Carnegie Institution of Washington, 115 West University Parkway, Baltimore, Maryland 21210.© 1986 by The University of Chicago. All rights reserved. 0031-5982/86/2932/$01 .00 Perspectives in Biology and Medicine, 29, 3, Part 2 ¦ Spring 1986 \ S149 the rise and fall of biochemicals, especially proteins in embryos, were documented. Embryology was in a cul-de-sac awaiting recognition and experiencing the ingrown sterility of isolation that has affected other fields. Eventual recognition and application to other areas of science made embryologists into developmental biologists. A wide range of disciplines is now used to explore developmental problems. Although formal programs that enhance sharing of information might be welcome, my own experience has been that an informal approach works best. Even international collaboration is best carried out by consenting adults. Official agencies assist in collaborative efforts more by removing impediments than by establishing programs. Several important laboratories in the field of embryology have played significant international roles in research and training. I immediately think of Ernest Hadorn's lab in Zurich, which kept Drosophila developmental biology alive until it could be fully resurrected by modern molecular genetics. Hadorn and his disciples helped train the modern Drosophila geneticists. Jean Brachet's lab in Brussels was central to the training of biochemists entering this field in the 1950s and 1960s. The international laboratories, such as the Naples Zoological Station, Utrecht Embryology Lab, and the Marine Biological Laboratory, also have played a role. My own scientific life has benefited enormously from international training and collaborations, all very informally started and finished. My perspectives were drastically changed by spending a year at the Pasteur Institute. In 1959-1960, some of the most exciting collaborative research ever accomplished was in progress there. Arthur Pardee had joined Monod andJacob in 1958 and had demonstrated the repressor of the ß-galactosidase gene [I]. The concepts of the operator and the promoter came during the year I was at the Pasteur Institute. Allostery was being discovered by Monod and Changeux in collaboration withJeffries Wyman in Italy [2]. Francois Gros and FrancoisJacob, with international collaborators, independently presented the first evidence for messenger RNA that year [3, 4]. There was a stream of international visitors through the laboratory, and great excitement. I spent my year in a 37° room working with one of Monod's primitive chemostats, studying what we called at the time the "glucose effect." To put it...