Maclyn McCarty (1911–2005)

One of the joys of staying with other people is the discoveries you make on their shelves of books you might otherwise not have noticed. I found this on our daughter-in-law’s shelf; it was part of her welcome packet when she was accepted to grad school. I don’t often read about science, but this book interested me. And with my laptop nearby, I could look up enough of the technical terms to understand the lab work descriptions. (This book was the first of a series, the Commonwealth Fund Book Program; its editor Lewis Thomas writes in the introduction that the series is aimed at interested laymen. If you get through this book without looking up any terms, you’re more scientifically literate than I).
This book is a first-person account of the discovery that DNA is the carrier of genetic information. It’s quite something to realise that there was a time, not too long ago, when scientists thought nucleic acid was the same in all living things and therefore not worthy of close study. The lab work by Oswald Avery, Colin MacLeod, and the author was the game-changer, yet, like many great discoveries, was the by-product of another project. As McCarty notes, this was a case in which research directed against a specific medical problem resulted in a contribution to fundamental biological knowledge. In public perception, it is often felt that only the reverse happens (p. 51). Avery and his colleagues were molecular biologists, working at the Rockefeller Institute in New York on the problem of treatment of bacterial pneumonia, which, at the beginning of the 20th century, was the leading killer, ahead of heart disease and cancer.
In the early 1930s, sulphonamide drugs seemed to offer hope. But why? How did they work? This was the first focus of their investigation. In the course of it, they observed that cultures of pneumococci that had been neutralised by the drugs were visibly different than their pretreatment counterparts. Virulent pneumococci were sugar-coated, that is, covered with capsular polysaccharides, a shiny coat that protected them. The inhibited bacteria lacked this coating and had a rough surface. Their curiosity was piqued by the work of another researcher who found that adding what he called an antigen from a different type of pneumococci to the rough bacteria resulted in production of a lively strain of that different type. Avery and his colleagues resolved the various antigens and identified the deoxyribonucleic acid (DNA) as the indispensable carrier. They did further experiments to rule out other potential factors and stood by their findings, although they did not feel in the position to follow up on their suspicion that their findings had implications for larger organisms. The compartmentalisation of science had already reached the point where the fact that they were molecular biologists, not geneticists, precluded this.
Nevertheless, their work did influence the course of discovery. Although Watson and Crick never conceded it in writing, McCarty is convinced that it was the work in Avery’s lab that led those researchers to focus their attention from the start on DNA and not on protein as the carrier of hereditary information, leading to their better-known discovery of the double helix.
This touches on one of the more interesting aspects of this book from the perspective of this interested layman. The bulk of the book recounts the work of Avery’s lab; it is preceded by McCarty’s memoir of his childhood, youth and studies (this, too, was interesting, giving me insight into how one becomes a scientist). But the final chapter, entitled Aftermath, deals with the reception of their work. In a way, it is a setting the record straight, or to put it more baldly, a settling of scores. There are clearly a few things that rankled McCarty. One was that their work came to be cited as a classic example of a “premature” discovery. I found the very term amusing; how can something be discovered before its time? McCarty however was not amused, and shows how, despite the year of their publication of their results (1944, when people had other things on their minds), and its appearance in a journal seldom read by geneticists, there were some who immediately saw the import. More painful was the baneful influence of another researcher at the Rockefeller Institute. At one point in their research, they approached him for a joint experiment involving an area of his expertise. In later years, this researcher felt he had been given insufficient credit and should be known as one of the co-discoverers of the genetic role of DNA. But for years before that, he had been the chief critic of their work, charging that sloppy lab work failed to rule out some other agent, such as undetectable protein. McCarty is at pains to demonstrate that sloppiness was not a failing of any lab run by Avery. McCarty also suspects that it was this researcher’s scepticism that influenced the Nobel academy to withhold recognition of their work. My takeaway from all this is that scientists are no less human than the rest of us. In addition to being seekers after truth, they also like recognition for the discoveries they make. All in all, a good read.… (mehr)