Lady Professor

by Switzer, Robert L. ;

  A couple of days after the lecture, he said to Emma, “Well, I may have a hell of a time getting promoted to tenure. Old Köhler was really upset by your lecture. Said you were attacking the German people.”

  “That’s nonsense. I was attacking the misuse of genetics by the Nazis.”

  “That’s what I told him, but I don’t think he objects that much to the Nazi government.”

  “Ugh. Well, even so, your promotion shouldn’t be affected by your wife’s opinions.”

  “No, but you know it is dependent on Köhler’s recommendation.”

  “Joe, you are an excellent teacher and carry a heavy load of classes. You’ve published research, and we’ll have more by then. You come up in forty, right?”

  “Yeah, two years from now.”

  “Maybe Köhler will have retired by then. It’s like me and Dean Woodrow. You just have to wait for the dinosaurs to die off.”

  CHAPTER 18

  1938 - 1939

  EMMA’S PREDICTION THAT the colored pigments accumulated by her mutant strains were intermediates on a step-wise pathway leading to the final product, Pigment A, was an insight that greatly speeded Joe’s elucidation of their chemical structures.

  Once he had figured out Pigment D, he quickly found that it was chemically closely related to Pigments B and C. Pigment B gave him the most trouble until he realized that it was an aldehyde that was readily oxidized during handling, a problem he solved by converting it into a stable phenylhydrazone derivative. Now, as he sat down at the kitchen table with the structures of all four pigments drawn on a sheet of paper, he saw how logically Emma’s postulated pathway was arranged. His sunny spirits mirrored the warm weather and fresh green of the June Saturday morning. Enrico sat on the floor near him, humming to himself as he constructed a tall, narrow tower of wooden blocks. Emma came into the kitchen and draped her arm fondly over Joe’s shoulder.

  “You’ve been so happy ever since you worked out the structure of Pigment B.”

  “Yes, because it all clicks together. Look at this. Your fungus cells are little chemists, Emma. Each intermediate pigment is converted into the next one by a chemical reaction that we might use in the lab. The first one, Pigment D, is an alpha, beta unsaturated primary alcohol. You predicted that it is converted into Pigment B, and all that takes is a simple one-step oxidation to an aldehyde—not so easy in the lab, but chemically simple. And the next step is another simple oxidation of the aldehyde to a carboxylic acid to make Pigment C.”

  “Oh, that fits perfectly with some things I’ve been reading in a biochemistry review,” she replied. “People have reported enzymes catalyzing those kinds of oxidation reactions in yeast and muscle.”

  “Remind me,” Joe asked. “What’s an enzyme?”

  “It’s a substance that catalyzes a very specific chemical reaction inside of cells. They make the reactions go much, much faster than they would otherwise. It’s pretty clear now that they are proteins. My old Cornell professor, James Sumner, has proven that. So why couldn’t the same kinds of oxidizing enzymes catalyze these oxidation steps: D to B and B to C?”

  “Makes sense to me.”

  “Don’t you see?” Emma said in a mixture of thoughtfulness and excitement. “I’ve been toying with this idea for a while now. Each gene is somehow responsible for one step in the pathway. And we think each step is a chemical reaction catalyzed by an enzyme. Ergo: the function of genes is to make enzymes. Not only in our fungus, but maybe in all living cells. Either the genes themselves are enzymes or they somehow instruct the cell how to make enzymes.”

  “Like little workers on an assembly line. Each one doing his little chemical job. Only they also teach their descendants how to do the same thing. Because genes are inherited, right? My God, Emma, you’re saying that’s how genes work—they make enzymes. That’s a big discovery, isn’t it?”

  “If it’s right, it sure is. One thing bothers me, though. What about the last step, C to A? That’s a funny looking reaction. The tail of the molecule curls around and forms that strange methylcyclohexene ring at the end of the chain.”

  “Yeah, that’s not such simple chemistry. It explains why Pigment A has a dark orange color, though, because it adds two more conjugated double bonds to a whole string of them.”

  “I’ve never heard of an enzyme that catalyzes any reaction like that.”

  “Me neither, but I don’t know anything about enzymes. Maybe no one ever looked for it. Besides, it’s a step that requires two genes, remember? pigC1 and pigC2. Maybe there are two steps and we never found the intermediate.”

  “Well, I think we’re on to something, something important. Why don’t you submit your structures to the Journal of the American Chemical Society? We have to wait until that’s published first, because our genes to enzymes hypothesis depends on the structures. Then I’m going to try to write this up for the American Journal of Genetics. That’s a really good journal. If it’s published there, people will take it seriously. After all, we’re not from one of the big universities.”

  They were interrupted by the clatter of wooden blocks onto the kitchen floor and a wail of distress from Enrico.

  “It doesn’t stable!” he cried. “It doesn’t stable!”

  Emma knelt beside her son. “No, ’Rico, a tower isn’t very stable when you make it so tall. But look. Let’s build another one. If we start with the biggest blocks on the bottom and put the littlest ones on top, it will be more stable.”

  “Mommy’s right, ’Rico,” Joe added, joining them on the floor. “And if you are careful to put each block squarely on top of the one below it, they won’t be so likely to tip over.”

  Smiling, but with tears still wet on his cheeks, Enrico returned to building his towers.

  Emma and Joe sat back.

  Emma caressed Joe’s hand. “Just like building a scientific hypothesis, huh? Block by block.”

  “Yeah.” Joe laughed. “And, like ’Rico says, it better stable.”

  EMMA HAD NEVER worked harder on the writing of a manuscript. She marshaled tables and a figure to present her genetic data and maps clearly and convincingly. Joe helped her create a figure that showed the chemical structures of the pigments and emphasized the simple steps in their conversion to the final Neurospora pigment.

  Emma concluded that the pigment was formed in a linear pathway in which each step was catalyzed by an enzyme. She cited examples of enzymes that catalyzed similar oxidation reactions, but had to concede that the final ring closing reaction was without a known precedent. She emphasized that each step corresponded to a specific gene and that mutations in those genes caused the step associated with it to be interrupted.

  She then reached the generalization that she knew had consequences far beyond the details of this study: “We propose that each of the pig genes specifies an enzyme that catalyzes a chemical step in pigment formation. It seems likely that the albino genes function in a similar fashion, but proof of that conjecture must await the isolation of the earlier intermediates in pigment formation, determination of their chemical structures, and correlation of defects in their formation with specific albino genes.”

  Then, as Joe would later put it, she reached for the moon. “We wish to suggest that our findings on the role of pig genes in determining pigmentation phenotypes in N. crassa may well be generalized to the mechanism of genetic expression in many, if not all, species. That is, we propose that, in general, genes exert their effects by, in as yet unknown ways, determining or causing the formation of specific enzymes, which in turn by virtue of their catalytic capabilities lead to the expression of phenotypes. Mutations, then, represent heritable alterations in the structures of genes that alter or obliterate the enzymes that execute the expression of those genes. Furthermore, since enzymes are now known from the work of Sumner, Northrup, Kunitz, and their colleagues to be comprised of proteins, we venture to suggest that some genes may specify proteins other than enzymes, proteins that confer structure or other properties on
the cells that contain them.”

  Emma admitted that it was not known by what detailed mechanism genes might “specify” proteins, but commented “since genes must be capable of undergoing precise duplication during cell division, perhaps their method of dictating or causing protein formation is related to the process of gene duplication.”

  She was privately inclined toward the idea that genes were actually self-duplicating proteins, but decided that such an idea was too speculative to include in a paper that already reached well beyond its data.

  Joe’s enthusiasm grew each time he read Emma’s latest revision of their paper. “This is really exciting. Imagine, a lady professor at little Harrington College explaining to the whole world how genes work.” He pushed his chair back and pulled Emma onto his lap. “Did you ever expect to come up with anything this big?”

  “No. I always wondered how genes work, but I thought that problem was too hard for me to solve. All I was trying to do was develop a fungus system that was simple and cheap enough to do genetics with here at Harrington. The pigment mutants were just a handy phenotype. We just kind of stumbled into it. I say we. It’s not just me, Joe. This paper is going to be by Hansen and Bellafiori. I couldn’t have put this together without your chemistry.”

  “Yeah, but you were smart enough to see that you needed a chemist.”

  “I needed this chemist. I didn’t even realize how much I needed you until I found you.”

  THEN CAME A period of waiting. The editor of the Journal of the American Chemical Society paper on the determination of the structure of the pigments required some revisions before it was accepted and could be cited as in the press, so three months elapsed before Emma finally submitted the paper by Hansen and Bellafiori entitled “Genetic Determination of Biochemical Steps in Carotenoid Pigment Formation in Neurospora crassa” to the American Journal of Genetics. More waiting: two months passed without a word from the journal, then three. Emma and Joe busied themselves with their usual obligations, but their anxiety grew as the period of silence lengthened. Should Emma contact the editor to ask about the review?

  Finally in February 1939 a thick brown envelop arrived in Emma’s campus mailbox. The large envelope meant that the mailing included a copy of the manuscript along with the editor’s decision letter. That was to be expected; editors almost always required revisions and returned the manuscript for that purpose. Emma nervously tore open the envelope, pulled out the letter, and hastily read it. Then read it again.

  The concluding line slapped her face. “I therefore regret to inform you that your submitted manuscript is not acceptable for publication and is being returned to you herewith.”

  CHAPTER 19

  1939

  “LISTEN TO THIS!” Joe shouted to Emma, waving the letter around as he stalked their kitchen. “‘The referee finds that the central conclusion of the manuscript, namely, that the genes of pigment formation act by specifying enzymes that catalyze reactions of pigment biosynthesis, is not logically compelling, because the authors have failed to demonstrate that the reactions they postulate are in fact catalyzed by enzymes. The mere isolation of putative intermediates in pigment formation that might be converted from one to the other by enzymes is not sufficient to establish that fact.’ That’s ridiculous. How else would those reactions occur? They’d be too slow and nonspecific without enzymes.”

  “Joe, I’ve read the letter a dozen times.” Emma replied wearily.

  “And all this hogwash. ‘The authors have extrapolated a modest study of an incompletely characterized pathway for pigment formation in a minor fungal species into a grandiose general hypothesis for the mode of action of all genes in all species. Such sweeping generalizations reflect an ignorance of the complexities of genetic expression and cannot be supported without further evidence. Particularly troubling is the authors’ failure to provide an explanation for precisely how genes could act to “specify” enzymes.’ Emma, that’s impossible. This guy has set the bar so high that no one could overcome it.”

  “Well, we won’t give up. I still believe that we’re really on to something. Let me think about it for a while.”

  After a few days Joe was still fuming, but Emma had shaken off enough of her anger and disappointment to begin thinking about how to respond to the rejection of their paper.

  “I guess we’ll have to do some enzymology,” she told Joe. “The referee is right. We didn’t prove that enzymes catalyze the steps we identified, but if we do that, I think we can re-submit the paper. I might have to tone down some of the discussion, but still get our basic new idea in.”

  “I don’t know anything about enzymes,” Joe grumbled. “How do we do that?”

  “It would be a lot easier if we could work with a biochemist. Is there anyone in the chemistry department?”

  “No. I told Köhler we should hire a biochemist, but he wouldn’t hear of it. Said it is a specialty for medical schools and it was sloppy science anyway. Stubborn old duck.”

  “Well, we’ll have to do it ourselves.”

  “What do we have to do?”

  “We’ll have to make cell-free extracts of the fungal cells and show that they catalyze the conversion of Pigment D into Pigment B, Pigment B into Pigment C and so on. The activities should be missing from extracts of the mutants. And they should be destroyed by treatments that are known to inactivate proteins, such as heat and enzymes that degrade proteins. That should be enough to convince any skeptic.”

  “That is a lot of work. And we don’t have any experience with it.”

  “I know it. But what choice to do we have? When you come up with a really new scientific idea, I guess you have to expect a lot of doubt. You need a lot more proof than for a paper that doesn’t challenge current ideas.”

  So they set to work. Progress was slow. Emma had to figure out how to make extracts of fungal cells that she harvested during the phase when they produced pigment actively. She had to remove all the remaining cells from the cell juice she prepared, because she knew that if she did not, a critic would say that the whole cells, not the cell extracts, were responsible for the reactions. She also knew from her reading that she would have to use gentle methods because enzymes are usually not stable in cell extracts. Joe had to devise ways of measuring the activity of the enzymes they were trying to study. That required separating one pigment from another. The column methods he had used to purify the pigments required far too much material be practical for measurements of enzyme activity. He needed a new, more sensitive separation method.

  Before Enrico was born, Emma and Joe had done most of their research work in the evenings and on weekends, but now they wanted to spend those times with their son, because they were away from him most weekdays teaching classes, meeting students and grading quizzes and exams. Enrico was a very bright, lively, and cheerful little boy. Emma and Joe took so much pleasure in their time with him that they willingly pushed their frustrating research to the side. They read children’s books—Mother Goose’s rhymes and The Little Engine That Could were favorites—to him over and over. Recently while chanting, “I thought I could. I thought I could,” with him, Joe playfully asked Enrico to point to the words. He did so correctly, tracing with his finger and repeating, “I . . . thought . . . I . . . could.”

  “Emma,” Joe called out. “Look, ’Rico can read these words.”

  Enrico glowed in his parents’ excitement.

  “Teach me more.”

  Thus began a game of writing words from his books on scraps of paper and asking Enrico to identify them, which he learned to do quickly.

  Emma took him on nature walks pointing out birds and flowers. Enrico was delighted when a robin built a nest on a tree branch where it could be observed from his upstairs bedroom window. He and Emma checked daily on the progress of its construction, the mother’s incubation of the eggs and the parents’ tireless feeding of their babies.

  “Are you trying to turn him into a biologist?” Joe teased.

  �
��You can take him to the lab and teach him chemistry when he’s older.” she replied.

  During the summer of 1939 Harrington College taught no classes, so Emma and Joe had more time to work on their attempts to study their enzymes. Emma found that she could grind fungal material with fine sand in a mortar and pestle and filter the extracted cell juice through diatomaceous earth to prepare solutions that were free of intact fungal cells on microscopic examination. Joe was stumped in his attempts to devise a sensitive assay for the enzyme activities they wanted to study until he stumbled across a report from two English biochemists who were using paper sheets to separate small quantities of materials in a way that was similar to how he had used columns of powdered cellulose.

  Paper strips could be hung from a tough of solvent—the same solvents he had used before—and mixtures spotted on the paper near the top were separated into colored bands of different pigments as the solvent slowly soaked its way down the paper. The strips had to be hung in glass tanks to keep the solvent from evaporating. Joe improvised this setup by using large glass pickle jars he got from a local grocery store. They were ready to start testing for enzyme activity.

  Joe’s work was interrupted by his six weeks of military summer camp, however, and after his return in August, they agreed to take a short vacation, which they had never done before. They would travel by train to Chicago and Stanton Mills to visit their families, whom they guiltily agreed they had neglected. Since the death of her mother, Emma had exchanged letters only infrequently with her sister-in-law Susan; her father and brother never wrote.

  “My father is getting old,” she said. “We should go see him and my brother and his family. Maybe my sister Kirsten too, if she decides she’s speaking to me. Enrico will love the farm. His cousins are quite lot older, but maybe they will get on.”

  “Fine. It’s way past time that they met your husband and our boy. And, if you can stand the racket, we’ll stay with my family in Chicago. Enrico’s got a whole lot of aunts and uncles and cousins to meet. Mama is always complaining that she hasn’t seen us since Christmas ’36, when Enrico was only one. I’m embarrassed that we haven’t been there in three years.”