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Return to Science

"You can't go home again" was never truer. It had been ten years since I had, in any sense, been a practicing scientist, ten years of revolution in my very own field of molecular biology. The advent of recombinant DNA and cloning, combined with DNA sequencing, polynucleotide synthesis, and genetic engineering, had broken a long-standing research barrier by permitting the isolation and identification and modification of individual genes from higher organisms. Whole fields of study—some long stagnant, some brand-new—had opened up in developmental biology, cell biology, virology and microbiology, neurobiology, and nearly every aspect of medicine.

In 1977, just prior to becoming chancellor, I had written a review for Annual Reviews of Biochemistry on the then new topic of recombinant DNA. After ten years of sophisticated genetic engineering of recombinant DNA vectors and the development of advanced techniques and instrumentation, that review was wholly obsolete. I had read occasional semi-popular articles in Science or Scientific American, but I had not kept up at all with the technical advances—which, in any case, would be meaningless without actual experience in their application.

Even more profound than the advances in technique were the enlarged perspectives and the deeper insights now available. Biologists have long marveled at the variety of living forms in the world of nature around us. We are now learning that the variety of biochemical mechanisms and processes within these organisms, built on a base of ancient, common strategies and structures, is even more exuberant, even more

extraordinary. Over billions of years, in myriads of species, nature the experimenter has explored and exploited all the changes, the combinations, the cyclic sequences of events to produce programs—cellular dramas—with common themes but of dazzling intricacy and variety.

If I were to reenter science, I needed to travel the usual entry track—as, in effect, a postdoctoral fellow. Caltech seemed the obvious place to do this. I knew most of the people; I knew the structures, physical and organizational; I knew the invaluable ambience. After ten years at UC, I was entitled to a year of sabbatical leave, so I would not need a salary. Caltech was willing to provide me with a small basement office and, most important, access for the year.

However, where would I go after Caltech? My faculty appointment was at Santa Cruz. In light of my own experience with a former chancellor on campus, I felt it would be much preferable not to be a faculty member at the same institution where I had been chancellor. It is awkward for the new chancellor to find a predecessor "popping up," in a sense looking over his or her shoulder. It would be difficult to avoid becoming involved in campus issues in which I had invested so much thought and energy, and I would indeed be pressured to do so by one faction or another. But I definitely should not. They are now the new chancellor's problems, opportunities, and responsibilities.

UC Santa Barbara appealed. It was a young and developing campus, with a growing reputation in the sciences, especially physical science. It had some distinguished biologists whom I knew. The climate was benign. And I had a house there, which I had built in the mid-1970s to use for vacations and which had been rented out all of the Santa Cruz years. The Santa Barbara biologists seemed pleased to have me join them. My appointment would remain at Santa Cruz; I would be on "temporary" assignment to Santa Barbara until my retirement as a faculty member, which would be mandatory in three years.

We rented an older house in Pasadena, near Caltech, and arrived in the midst of a heat wave, just in time for the jolting aftershock of the Whittier earthquake. But Pasadena was still familiar.

Returning to science after an enforced abstinence was a joyous journey. I could savor anew even the process as well as the content: the familiar rhythms and flow of a scientific meeting, the large general lectures and the smaller specialized sessions, the little knots of people, some old friends, some new acolytes, discussing a presentation—or where best to go for dinner—and above all the pervasive sense of progress, of advance, since the prior meeting.

Even the easy rituals of the late afternoon seminars were fresh and pleasing: the faculty largely in the first few rows, the students scattered behind them; the introduction of the speaker, the standard acknowledgments to coworkers and students before launching into substance, the background, the recent results, the future plans; then the discussion period, sometimes respectful, sometimes probing, sometimes brash, sometimes almost harsh, but impersonal. All the familiar and heuristic patterns, time-tested and leading erratically but surely to truth, once again shone and refreshed.

Much of the fall quarter was spent reading, talking to everyone in biology, attending numerous seminars, and catching up on the state of the science. But I clearly needed to get into the laboratory. With recombinant DNA, developmental biology had emerged from a fifty-year slumber. Finally, one could begin to study the genetic and biochemical components, the hierarchy of controls that underlay the intricate processes leading from a single fertilized egg cell to a mature organism. Eric Davidson's laboratory was most active in this field, so I signed on with him as an apprentice postdoctoral fellow.

The postdoctoral fellow in science has in many ways an idyllic existence. He or she has no responsibility other than to come in and perform research. The professor provides the laboratory, the facilities, the funds for supplies. Undistracted by teaching, committees, or fund-raising and with such recent training, the fellow is ideally positioned to concentrate for a few years on problems at the most advanced edge of the field. Of course, I had one advantage over the other postdoctoral fellows—I did not have to worry about finding a permanent position in two or three years.

Getting back to the laboratory bench, doing experiments with my own hands, coming in in the morning to see how an overnight experiment had worked out, reviewing results, and exchanging ideas with others in the laboratory was sheer pleasure. Initially, I was quite ignorant of the new techniques, but other fellows and students were most helpful. Once past the early blunders, most of the techniques are actually rather simple to use, save for the occasional total failure due to a mental lapse or, more often, a bad batch of reagents or an equipment malfunction.

Development implies a programmed pattern of controlled differential gene expression in the varied cells of the developing embryo. The research in Davidson's laboratory used embryos of sea urchins—a classical object of embryonic research—which can be obtained in large

numbers and accurately synchronized. The object of the research at that time was to isolate and identify factors—proteins—responsible for turning on and off specific genes at specific stages of development, and then locate the genes responsible for these factors. Ultimately, we hoped to arrange all of these in an hierarchical structure, beginning with the fertilized egg, that could explain the appearance of different functions and organs at the different stages of development. Some genes controlling analogous factors in drosophila had been isolated and sequenced. It was plausible that similar genes existed in sea urchins. If so, techniques existed to identify, and then isolate, these by their homology to the drosophila genes. I set out to do this.

In the laboratory, I was immediately struck by the ready commercial availability of sophisticated biological reagents. A whole ancillary industry had sprung up to provide the many enzymes, polynucleotides, engineered plasmids, viruses, cell lines, and highly purified reagents needed for modern molecular biology. I recalled the era when one had to go to the stockyards to obtain intestines to prepare alkaline phosphatase and thymus glands for DNA. As recently as the 1970s, we had had to prepare our own restriction enzymes. Now a hundred different varieties could be purchased at quite reasonable cost. This development greatly accelerates the pace of research.

Still, as always, the research went more slowly than I hoped, but by summer I had had some success. Now it was time to move to Santa Barbara, where it would be difficult for me to continue this project on my own. But I had mastered a variety of essential techniques.

The biology program at Santa Barbara, because of leaves of absence and pending retirements, needed me to perform some of their essential teaching for a few years. I welcomed the challenge. And it really was a challenge.

The third quarter—thirty lectures—of the required biochemistry course concerned nucleic acids and protein synthesis. This had been my field of interest and research for decades and I had taught varied aspects of this subject at Caltech.

As I prepared to teach this course after a ten-year hiatus, I was astonished and thrilled by the progress made in the past decade. In every sector, the advances had been simply extraordinary: in the intricacies and nuances of DNA structure (no longer the simple rigid double helix); in the still deepening complexities of DNA replication (initiation, strand elongation, termination); in the much expanded understanding of DNA transcription and its control; in the knowledge of the process-

ing of RNA transcripts (capping, splicing, tailing); in the comprehension of amino acid activation and ribosomal structure and the many facets of protein synthesis (initiation, elongation, termination); in the variety and importance of DNA repair processes; in the growing knowledge of chromosomal structure and the enzymology of genetic recombination; and, of course, in the whole world of recombinant DNA with its skillfully designed vectors, the elegant methods of oligonucleotide synthesis and DNA sequencing, the wealth of restriction enzymes, the new polymerase chain reaction, and so on—a true biological engineering.

Practically, I had difficulty in planning the time required to treat each topic, and in the end I estimated that over half of the material I taught in the course had simply not been known ten years earlier.

Between organizing the lectures, preparing transparencies for projection and Xeroxed handouts for eighty students, meeting with students who had questions, planning the discussion sections with the teaching assistant who would lead them, and giving and grading midterm and final examinations, the course was a ten-week marathon occupying nearly every. waking hour. I learned a lot, and it was truly enjoyable to be able to talk about science and once again interact with students in a nonconfrontational mode.

A series of ten lectures on the cell nucleus in a graduate course in cell biology was a similar, but briefer experience. Quite different, however, was a series of lectures on genetics to a beginning biology course for students who did not plan to major in biology. A popular way to satisfy the science portion of the general education requirement, the course was limited to 475 students only because of the size of the lecture room. The room was actually a concert hall with no blackboard and a sea of faces. In such a course there can be very little direct interaction with students. The presentation must be very largely visual. I used slides, transparencies, films, videotapes (e.g., Nova programs)—whatever I could find that was appropriate. Today's TV-habituated students seem better able to learn from visual presentation than from textbooks. But as they are accustomed to the high technical standards of commercial television, the visual material has to be of a similar quality.

Soon after I arrived at Santa Barbara, I learned of the research of Professor Paul Hansma in the physics department. Hansma had developed an "atomic force microscope" with which he had been able, with favorable substrates, to obtain atomic resolution on surfaces. It occurred to me that this instrument might, just might, be able to resolve the

individual bases in DNA and if so permit one to achieve the direct sequencing of a DNA chain. Such an accomplishment would, of course, greatly advance the Human Genome Project. This was and is a "long shot," a "high-risk" experiment with the possibility of a dramatic result. It was not an experiment that one would give to a graduate student who must complete a thesis and write some papers for his career, but I could take the chance.

Paul Hansma was intrigued with this possibility and together with his wife Helen, who is a biologist, we set out. We have been looking at simple polynucleotides of known sequence. In such research there are always many possible approaches (Should the nucleic acid be dry, under water, under a nonaqueous solvent?) and technical difficulties (What supporting surface should be used? How can we keep the nucleic acid from moving about? Is temperature important? Can we minimize possible damage to the nucleic acid or is that not a problem?) To date we have had modest success. Our resolution has been such that, under favorable conditions, we can detect the presence of the individual nucleotides in a chain but cannot differentiate them. Could we modify them to make them more distinctive? Would other modes of mounting the DNA be more productive?

The research continues, and it is fun. And the reports of progress in each new journal, the new discoveries presented in the weekly seminars, and the new insights that come from reflecting on these all stir the same excitement, the same pleasure and wonder, as always. Science is a glory of the human mind and these are glorious times in which to be a biologist.