R. Clinton Fuller

Photosynthesis Research62: 1–29, 1999.© 1999Kluwer Academic Publishers. Printed in the Netherlands.

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Personal perspective

Forty years of microbial photosynthesis research: Where it came from andwhat it led to ∗

R. Clinton FullerDepartment of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA

Received 14 May 1999; accepted in revised form 15 August 1999

Key words: chloroplast, chlorosome, chromatophore, granules, inositol,Neurospora, path of carbon, pho-tosynthesis, polythdroxyalkanoate (PHA), prokaryote cellular inclusions, protozoan biochemistry, ribulose1,5-bis-phosphate,Tetrahymena

Abstract

What follows is a very personal account of my professional life and the early years that preceded it. I have describedthe social and economic conditions in America and how the nineteen twenties and thirties nurtured our scientificfuture. The description of the early part of post-World War II research covers my experience in the areas ofnutritional biochemistry, biochemical genetics and proceeds to photosynthesis. The latter era lasted around 35years. For me the most memorable research accomplishments in which I was a participant during this period wasthe first demonstration of the primary carboxylation enzyme in anin vitro system in algal and higher plants as wellto show that it was structurally associated with the chloroplast.Our group while at Oak Ridge and the Universityof Massachusetts assembled data that described the complete macromolecular assembly of the photosyntheticapparatus of the unusual photosynthetic green bacteriumChloroflexus aurantiacusand created a model of thatsystem which differed greatly from the chomatophore system for the purple bacteria. For the last decade, myscientific journey, with numerous new colleagues has turned to the exciting area of biomaterials.We characterizedand modeled the completely new bacterial intracellular inclusions responsible for the synthesis and degredation ofbiosynthetic, biodegradable and biocompatible bacterial polyesters in the cytoplasm ofPseudomonads.

Abbreviations:ATP – adenosine 5′triphosphate; NAD and NADP (formerly DPN and TPN) – nicotinamide adeninedinucleotide and nicotinamide adenine dinucleotide phosphate, respectively; RUBP – (formerly abbreviated asRUDP) ribulose 1,5 bis-phosphate

Introduction

When Govindjee asked me to write my personal per-spective article for the ‘Historical Corner’, I hesitatedover how to compile a readable paper about my half-century involvement in science. Reading a dozen or soprevious perspectives concerning photosynthesis re-search that had been written for the ‘Historical Corner’showed me a wide variety of approaches. All of thearticles were excellent pieces of scholarship. How-ever, I was impressed particularly by the approaches

∗ Written at the invitation of Govindjee, Editor of the HistoricalCorner.

taken by my former colleagues David Walker (1997),Howard Gest (1994), George Feher (1998) and Ger-hart Drews (1996); their papers seemed to fit so wellwith their personalities. Encouraged, I decided to letmyself be driven by my own personality – come whatmay! I have been very fortunate in my colleagues overthe years. The prolific, scholarly writings of HowardGest (1992) on the role of serendipity in both the gen-eral area of science and, specifically, in photosynthesisas well as Royston Robert’sSerendipity– AccidentalDiscoveries in Science: A Micro-history of the Phe-nomenon(Roberts 1989), have greatly influenced mein writing this personal perspective. These authors em-

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phasize that chance happenings play a tremendous rolein the advances of science and in scientific careers.They also profess that the scientist must be able tograsp the event created by a serendipitous situationand proceed accordingly. With the above in mind,I believe that unexpected events in science lead toeventual progress. Taking advantage of chance cir-cumstances requires not only solid training in the areaof endeavor, but also the selection of people with theinherent instinct to take advantage of these unplannedhappenings. Roberts quotes two famous nineteenthcentury scientists, Louis Pasteur and Joseph Henry,both of whom became famous for their discoveriesin chemistry and physics respectivly due to a seriesof unexpected events. Pasteur was originally trainedas a chemist, but also influenced the world throughhis work in both microbiology and immunology. Evenmore importantly, he discovered chirality or isomersin organic molecules. His discovery occurred througha series of chance observations: when crystals of tar-taric acid and ‘racemic’ acid (identical molecules butthe former a synthetic product) were examined un-der a microscope, they formed crystals that formed‘left hand’ and ‘right hand’ structures. These exper-iments confirmed their observations using polarizedlight analysis. Pasteur summarized the importance oftraining: “In the field of observation, chance favorsonly the carefully prepared mind.” Joseph Henry, thedistinguished American physicist, expressed the sameprinciple: “The seeds of great discoveries are con-stantly floating around us but only take root in mindswell-prepared to receive them.” Success in science is atruly Darwinian process.

The beginnings: March 5, 1925 and December 7,1941: Two days that will live in infamy

My birth coincided with the giddy excesses of the mid1920s when jazz and bootlegged liquor numbed oursociety to social and economic reality. From 1925–1932, laissez-faire government maintained a sharpsplit between the wealthy and the disadvantaged. Awildly rising stock market masked conditions thatwere becoming increasingly depressed. Banks folded.Agriculture and industries from mining to textiles col-lapsed. Cities teemed with unassimilated immigrants.Our culture largely stagnated with some exceptions inliterature. F. Scott Fitzgerald described the desperateself-indulgences of the wealthy in a spiritually vapidtime. The most important literary contributions, how-

ever, probably emerged from writers fueled by a newrealism. Theodore Dreiser, Sinclair Lewis and JohnSteinbeck all pitted the gritty realities of poverty andinjustices of the social structure against the AmericanDream. It would take the devastating turmoil of theGreat Depression and World War II to redirect our so-cial, intellectual and, particularly, scientific priorities.Refugees from the persecutions in Europe flooded ourcountry; many of these or their children became thedistinguished scholars of the next few decades. Gradu-ates from US colleges, unable to find jobs, turned tograduate studies. For instance, City College of NewYork requiring no tuition, sent their students on to thebest institutions for a PhD education even while 25%of our population lacked work. My generation of sci-entists found some of its greatest teachers among thesegraduate students.

My own initiation into science was interwovenwith the progressive post-Depression federal programsthat funded our public health and natural resources aswell as the arts and humanities. One such program wasthe Public Health Service, the embryonic source of theNational Institutes of Health. Agendas for forestry, aswell as natural resource preservation, were set up bythe Department of the Interior. The Department of Ag-riculture not only boosted agricultural research for ourown nation by strengthening the United States Depart-ment of Agriculture Research Laboratories, but alsodeepened our commitment to other countries by in-cluding world food production in its agenda. PresidentFranklin Delano Roosevelt, with the urging and parti-cipation of his wife, Eleanor, also funded the arts andhumanities under the Works Progress Administration.Science, during this period, received most of its sup-port from the private foundations such as Rockefeller,Carnegie and Ford.

An introduction to science: 1943–1952

When the Japanese bombed Pearl Harbor on Decem-ber 7, 1941, I was a 16-year-old high school junior.My age group had little choice about the future sincethe draft only exempted those under the age of 18 orthose with physical disabilities (including flat feet!).Under the Roosevelt administration policy, inductioninto the armed forces was delayed until an 18-year-old had graduated from high school; at that pointhe either would be drafted into the Army or couldvolunteer for the Navy or the Marines. War veter-ans were able to enter college and receive 4 years ofgovernment-supported education as a result of another

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forward-looking policy of the Roosevelt and the HarryS. Truman administrations.

Choosing the Navy turned out to be a lucky eventaffecting my career in science. The Navy had set upthe so-called V-12 Program which could be entered ifa highly competitive exam were passed. The program,much broader in terms of professional choice than asimilar one set up by the Army, allowed all enlistedpersonnel with high school diplomas to be sent onactive duty to a university for the training to becomea lawyer, doctor, engineer, teacher, scientist or otherprofessional. I was accepted into the V-12 Programand assigned to Brown University in July of 1943.

Since I had expressed interest in the life sciences,my assignment was to major as a pre-med student. Iremember my mother exclaiming with joy, “Eureka,my son the doctor!” I simply groaned over having totake a lot of chemistry that I nearly had flunked inhigh school. With less than impressive motivation, Istarted the very demanding Navy program. For everysingle month of the year, we students took six coursesa semester in order to attain the Bachelor’s degree intwo years. Courses in ‘Leadership’ diluted our intel-lectual pursuits (reminiscent of our current ones in‘Cultural Diversity’?). Two miles of formation run-ning, marching to meals, various military formationsand drills punctuated each day. Many of us becamedisciplined and healthy despite ourselves. Nonethe-less, we all looked for ways to reduce the heat of thisrigorous schedule.

Just as with the students of today, we tried to fit oneor two ‘gut courses’ into our schedules. I chose Music101 that looked like a breeze to me as classical musichad filled my upbringing. In this class I met the womanwho was to become my wife and wonderful, lifelongpartner. Music 101, taught by a great musician, in-spired us beyond the marching drill beats to the highlyskilled but delicate rhythms of Mozart and to the headyjazz rhythms of Benny Goodman, Tommy Dorsey andGlenn Miller. Carol, my future wife, sat next to me.Soon we were comparing notes on English, her major,and science that left her cold. However, we overcamethe barriers before long and exchanged our interests.While I enrolled in a Restoration Drama class, Caroltook Biology 101 taught by Professor George Kidderwho had inspired me in a biochemistry course and,later, would launch my career. In more ways than one,Music 101 and Biology 101 were fortuitous events inour lives.

Soon circumstances beyond anyone’s control againtransformed my life. Due to graduate in Septem-

ber1945, I had expected to be off to the Far Eastand the invasion of Japan. Instead, the Allies bombedHiroshima and Nagasaki. With the sudden end ofWorld War II in August, I found myself dischargedinto civilian life as an unemployed college graduate.However, I would be able to continue research withGeorge Kidder at his invitation. I had taken several ofhis courses and spent time (mostly washing dishes) inhis lab. More importantly, I had become involved indiscussions about biochemistry. Indeed, I had becomevery interested in his research.

At this time George was studying the comparat-ive biochemistry of nutrition in the Protozoan ciliateTetrahymena geleii. His contention was that all anim-als not only had the same nutritional requirements foramino acids as well as various vitamins, but also thesame precursors and pathways for synthesizing pro-teins, nucleic acids and carbohydrates. It was indeeda perfect model system for studying animal biochem-istry. His first contribution was the successful growingof Tetrahymenaon a defined media of the 18 essen-tial amino acids, glucose and cofactors from yeastextract or liver. In a liver extract, an element that wasnot present in yeast was identified as being requiredfor growth; it was designated ‘liver factor II’. Whenpurified and characterized, this factor turned out tobe folic acid. This discovery confirmed for Georgethat Tetrahymena, like all animals, required this vit-amin. My first scientific paper, published 53 yearsago, concerned this work (Kidder and Fuller 1946). In1947, George presented this material at a symposiumof the American Society of Biological Chemistry inAtlantic City, New Jersey. An enthusiastic lecturer,he had emphasized his belief that the ProtozoanTet-rahymenawas a “nutritional and biochemical animal”.André Lwoff of the Institute Pasteur opened the ensu-ing discussion with, as I recall, the following question:“George, in your examination of this animal, have youdiscovered any other characteristics that might suggestan even more highly evolved animal? Have you, forinstance, ever observed thatT. geleiihas hair or mam-mary glands?” George quickly replied, “Hair, yes, it is,of course, a protozoan ciliate. But mammary glands?Not yet. But we’re looking!”

Besides being a superb teacher and world-recognized biochemist, George was ambitious for hisstudents. Soon after I had started to work for him as aPhD student at Brown, Amherst College offered him aposition. So my new wife, the converted English ma-jor, and I began to anticipate a move. George warnedme that Amherst College did not give a PhD. However,

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I could obtain an MA degree through a cooperative ef-fort among Amherst, Mt. Holyoke and Smith Collegesas well as the newly named University of Massachu-setts. Then he would see that I entered a first class PhDprogram elsewhere.

So, in the fall of 1946, Carol and I – newly married– trekked north to Amherst where time passed rapidly.When my MS was in hand, George again helped byurging me to involve one of two eminent scientistsfor my PhD work. He suggested either E.L.Tatum,then at Yale or George Beadle at Cal Tech. (that bothof these scientists would win Nobel prizes was obvi-ous to George). Applying to both places, I receivedimmediate acceptance by Yale but not by Cal Tech!California, however, was not out of the picture sinceanother serendipitous event cropped up. George re-turned from a meeting around Christmas, 1945, andexclaimed, “Clint, you’re in trouble. Ed Tatum is leav-ing Yale and going to Stanford. You better go down toNew Haven and talk to him.” By the end of the day, Ihad the option of staying with David Bonner at Yaleor joining Tatum at Stanford with full support and atuition waiver. It was a tough decision for me. JoshuaLederberg, one of Tatum’s senior students, indeed didfinish at Yale; eventually sharing the 1960 Nobel Prizewith Beadle and Tatum; he later became the presidentof Rockefeller University. For me, however, the Westwon out. I joined ranks with Tatum, his associates andstudents. Carol and I stuffed all of our belongings intoa used 1938 Ford and headed for Palo Alto in the latespring of 1948.

The first task for the Tatum team was to build acouple of constant temperature rooms and 200 hand-made test tube racks; we hoped that our stipends forthis work would be handsome. For the next 2 months,one-inch turkey wire, cutters and pliers bloodied ourfingers as we formed the racks. At the end of the sum-mer, Ed presented each graduate student with $100.Overwhelmed by the enormity of our reward, we de-cided to head for Yosemite National Park for a weekof camping before school started. Together with ourfamilies, we rapidly blew our stipends on steaks andgood California wine ($1.00 a gallon for Gallo’s best).We all got to know each other very well that summer!

Exciting and important, the years at Stanford(1948–1952) passed all too quickly. The era heral-ded the field of molecular genetics. James Watson andFrancis Crick had not yet appeared on the scene. Thework of George Beadle, a geneticist, and Ed Tatum,biochemist, held center stage in the gene expressionbeginnings. “One gene – one enzyme” was the cry of

the lab at Stanford. For the next 4 years, we all wereinvolved. My PhD thesis gave me a terrific backgroundin Neurosporagenetics. My research also introducedme to cell biology and to the biochemistry of cellu-lar structure and function at the macromolecular level.These research areas would be the ones that I wouldbe involved in for the rest of my career in both pho-tosynthesis and biomaterial sciences. My PhD thesisinvolved a mutant ofNeurospora crassathat requiredthe vitamin inositol for growth. When grown on limit-ing amounts of this vitamin requirement, the organismshowed a slow growth rate and small colonies onagar rather than fast-spreading mycelial growth. Ialso discovered that wild-typeNeurosporagrown onhexachlorocyclohexane (an inhibitor of inositol meta-bolism) induced the wild-type organism to behavesimilarly, in both growth rate and morphology, to theinositol requiring mutant. At this time the biochemicalrole of inositol was unknown. It was later shown thatit was incorporated as a phospholipid in mitochondrialmembranes and that its absence caused the cells tobe respiration deficient, which accounted for their re-tarded growth and morphological changes. My thesisresulted in two publications and a little bit of the in-tellectual glory of the Tatum, Beadle and LederbergNobel Prize in 1960 (Fuller et al. 1956; Fuller andTatum 1956)

By May of 1952, I was finishing my degree andfound myself short-listed for several academic jobsbut without any sure employment prospects. (In thosedays post-doc positions were not a requirement forstarting positions at universities.) A little desperationcrept into our family life, now supplemented by twoinfants. Again serendipity came to the rescue. EdTatum was the faculty head of the Sigma Xi HonorarySociety at Stanford. As such he had invited a chem-ist, Melvin Calvin from the University of Californiaat Berkeley, to give the annual Sigma Xi lecture, en-titled “The Path of Carbon in Photosynthesis”. Ed, asalways, involved his students in social events centeredupon distinguished visitors. So we all were invited tothe Tatum house for a barbecue and to meet Calvin.When I was introduced, he remarked, “Well, youngman, I understand that you’re just finishing up yourdegree – what do you plan to do with the rest ofyour life?” Undaunted, I quickly answered that I waslooking for a job. When he asked if I considered my-self a microbiologist, I immediately replied in theaffirmative. (At that point I would have said yes toanything!) Then he asked me if I could come up toBerkeley where they were having a lot of trouble with

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Figure 1. Picture of the Calvin photosynthetic group in 1954 outside of the Old Radiation Laboratory in Berkeley. Left to right: Ning Pon;J. A. Bassham; Jean Bourdon, Paris, France; R. C. Fuller; Rodney Quayle, later Vice-chancellor of Bath University, England; Hans Kornberg,Oxford, later Professor of Biochemistry, Cambridge University (now Commonwealth Professor Sir Hans Kornberg at Boston University); HansGriesbach, late Professor and Head of Botanical Institute, Albert Ludwig’s University, Freiburg; Alice Holtham, Department secretary andartist; Malcolm Thain, England; Melvin Calvin; Paul Hayes, Laboratory Manager; Jacques Mayoudon, post-doctoral student from Belgium;and late Professor Kazuo Shibata, Riken, Tokyo, Japan. This was a typical group during the 1940s, 1950s and 1960s. Missing in the pictureis Andrew A. Benson, who took the picture. Reprinted from Calvin (1961). Photograph is a courtesy of Lawrence Radiation Laboratory,University of California at Berkeley, California.

yeast growing in their algal cultures and needed a“microbiologist to clean up the situation”.

Thus I gained a position as Research Associate inMelvin Calvin’s laboratory. Showing the lab to me,he commented that he hoped I liked it as 60–70 hof my week would be spent there for the next fewyears. He was so right! With PhD in hand, I movedmy family to Berkeley on July 1, 1952. My salary wasa princely $6000 a year! Melvin introduced me aroundto the other staff, visitors and students associated withphotosynthesis. (Melvin had an equally large groupinvolved in animal cell biochemistry.) Figure 1 is aphotograph of the photosynthesis group, which wastaken in 1954 outside of the ‘Old Radiation Laborat-ory’ on the Berkeley campus. This picture was takenby A.A. Benson.

The Calvin years: 1952–1955

My research with the Calvin group at the Old Radi-ation Laboratory (ORL) was one of the most excitinglearning experiences in my career. For the next 35years, I was launched into the area of the cell biochem-istry and comparative structure related to function inmicrobial photosynthesis. Worldwide research in pho-tosynthesis concentrated in the following areas at thattime: the biophysics of solar energy capture; the con-version to chemical-reducing power in the form of re-duced pyridine nuceotide; the production of ATP; andthe path of carbon after CO2 fixation. This researchsurged tremendously during the 1950s and 1960s. Thediscovery and use of14C by Sam Ruben of the Chem-istry Department at Berkeley and Martin Kamen atthe Radiation Laboratory in the late thirties, opened

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the way for studying the new (for those days) radio-active tracer technology and the mechanism of photo-synthetic CO2 fixation. The giants of these areas ofphotosynthesis research included: Eugene Rabinow-itch, Otto Warburg, James Franck, Robert Emerson,William Arnold, Cornelis B. van Niel, Hans Gaffron,Daniel Arnon, Jack Myers, Melvin Calvin and histwo long-time associates, Andrew A. Benson and J.Alan Bassham, as well as many others. These scient-ists actively produced theories, probed and obtainedexperimental results that hopefully backed their pro-posals. I was fortunate to have had various interactionswith all of them. The conflicting ideas sometimesgenerated bitter arguments that polarized we youngerparticipants behind our leaders and their respectiveresearch philosophies and concepts. In the literaturethese sharp exchanges were subdued by the review-ers to far more civility than thought necessary at thepodiums or on the floors of many memorable meet-ing places. At Gattlinburg in the Tennessee SmokyMountains, Brookhaven National Laboratory and atseveral universities that hosted meetings of the Amer-ican Society of Plant Physiologists, the argumentscould flair up into brutal attacks. The depth of thepersonal enmity among the giants shocked us youngerparticipants (Seaborg and Benson 1997). With some-what less responsibility for our profession than ourtruly great mentors, we got to know each other’s re-search, different backgrounds and approaches and intime we appreciated how much healthy competition,education and stimulation actually resulted from ourleaders’ conflicts. Many of us became good friendsand colleagues over the years.

Two major scientific thrusts filled the early 1950s:one involved the path of carbon; the other involved theprimary photochemical act of energy capture and itsconversion from light to chemical energy. I entered theCalvin group when about 20 staff along with graduatestudents and post-docs were working on the photo-synthesis project. In addition many visitors, selectedcarefully on the basis of their abilities to enhance bothareas of photosynthesis research, also contributed im-portant work. Initially, Andy Benson used the newanionic and cationic resins from Dow Chemical Co.as a purification media for the isolation of14CO2 pho-tosynthetic fixation products. (Calvin was a long timeconsultant for Dow.) Subsequently, Bill Stepka, alsoat Berkeley, introduced the lab to paper chromato-graphy and radioautography as analytical techniquesat the ultrasensitive tracer level. Gaffron’s group made

many discoveries,particularly in energetics, that keptthe Calvin group on the right path (Gaffron 1960).

I cannot emphasize enough the importance ofthese technologies either utilized or designed by thosepeople involved in the Calvin years. The imaginat-ive staff together with intelligent students and visitorsdesigned new instrumentation and technology for theanalysis of the photosynthetic process. All of the ini-tial work used14CO2 and algae, as the plant of choice,to trace the path of carbon; this work depended upona simple piece of glassware invented by Andy Bensonand designated, for its obvious shape, as the ‘lollipop’(see Figure 2).

After turning on the lights, one simply held thelollipop with one hand and injected14C-labelled bi-carbonate solution into the vessel with the other hand.Then one opened the stopcock as rapidly as possiblein order to kill the algal suspension in boiling 95%ethanol. Proficiency with this process meant that the14CO2 fixation could be stopped after about 5 s in thelight. This type of procedure produced chromatogramswith many labeled sugar phosphates and phosphogy-eric acid (PGA). The latter was indicated as an earlyif not primary fixation product. The only difficult as-pects of the procedure were that the experiments hadto be carried out at room temperature and that, need-less to say, timing the formation of fixation productswas not reproducible. Further, we were not really ableto study the kinetics of the reactions, and the amountof material14C-labeled compounds was so small asto make analysis difficult. One instance of chemicalinstrumentation and engineering involved the ‘algalsteady-state apparatus’ designed by Alex Wilson (agraduate student from New Zealand) under the direc-tion of Al Bassham and Andy Benson. Experimentsin this apparatus could be carried out at low temperat-ures so that the enzymatic reactions were slowed down(Calvin et al. 1954). TheJournal of the AmericanChemical Societypublished, as part of Alex’s thesis,a detailed diagram of that apparatus together with itsfunction and capabilities for illuminating the path ofcarbon work.

Both the diagram and legend to Figure 3 evokehistorical interest since the drawing must be the mostcomplicated to ever pass reviewers and then be re-duced to one column of fine print. Several of us triedto talk Melvin out of publishing this unintelligiblemasterpiece without further simplification. We failed.However, just prior to submission of the manuscript,several staff members (who will remain unnamed)colluded with the departmental secretary and artist-in-

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Figure 2. All of the early experiments from 1947–1953 with14CO2 and algae were carried out with this apparatus, the ‘lollipop’ as describedin the text. Reprinted from Calvin (1991). Courtesy of Lawrence Radiation Laboratory, University of California at Berkeley, California.

residence, Alice (Holtham) Lauber, to add a simpli-fying entity to the figure. That entity, reproduced inFigure 3 between n and A in the center of the algalsuspension tank, shows a simpler way to fish for data.Melvin missed our addition to the drawing. The re-viewers and publishers also missed it. But theJournalof the American Chemical Societypublished our ad-ded simplification which still survives in the archivesections of most science libraries (Wilson and Calvin1955).

Visitors also made essential contributions to ourwork. Arnold Nordal, a Norwegian of worldwidestature in plant synthesis and storage of sugars as wellas sugar phosphates, together with Gerard Mihaud,from the Institute Pasteur, contributed vitally in theareas of biochemistry, metabolism and enzymology inmicroorganisms. Other visitors, some of them long-term, included Rod Quayle, a recent PhD graduatefrom London and later Vice-chancellor of Bath Uni-versity; Hans Kornberg, later Sir Hans and Professorand Chair of Biochemistry at Cambridge University;and Hans Griesbach, later Professor and Chair ofBotany at Albert Ludwig University in Freiburg, Ger-many. This wonderful group, under the daily supervi-

sion and mentorship of Andy Benson and Al Bassham,plunged into the path of carbon research. John Baltrop,a Professor of Chemistry at Balliol College, Oxford,was recruited to enhance the second major thrust ofthe lab, which was the primary photochemical act ofenergy capture and conversion from light to chemicalenergy. As a physical organic chemist, he interactedwell with Melvin’s creativity and intuition.

This young, vigorous group of associates, whichgathered under one scientific roof to work on a majorproject, formed an early example of the interdisciplin-ary approach to the life sciences. Similar approachesexisted in the Manhattan Project and at places likeChicago and Oak Ridge. But the focus on such a smallarea as photosynthesis with a great team of biologists,chemists and physicists was certainly Melvin’s cre-ation. Along with both Andy Benson and Al Bassham,who was with Melvin for his whole career, we allgreatly benefited from that interdisciplinary approachin our future careers.

I would like at this point to express a personal notethat represents my own feelings and the recollectionsof many of the scientists who with me experienced theresearch years at the ORL in Berkeley on photosyn-

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Figure 3. Diagram of the apparatus for measuring transient phenomena. The apparatus itself consists of an illumination vessel ‘A’ and three gassystems. One is a recycling system for high partial pressure of CO2; one is a non-recycling system for12CO2, and the third is a non-recyclingsystem for14CO2. It is possible to switch between the recycling system and either of the non-recycling systems by turning three stopcocks onthe control panel ‘B’, and also to switch between the non-recycling systems by turning stopcock ‘a’. The gas is continuously monitored for CO2partial pressure and radioactivity by an infrared gas analyzer and an ionization chamber, respectively, ‘C’. The data are recorded continuouslyand automatically on chart recorders, ‘D’. The monitors may be placed ‘before’ and ‘after’ the illumination vessel by turning two stopcocks ona control panel (‘E’ shows how the stopcocks located below should be turned). When the ‘high’ recycling system is in operation the gas passesthrough a large reservoir ‘E’ (5 l). This reservoir can be bypassed by turning stopcock ‘b’, leaving only a very small volume recycling. Underthese conditions the rate of photosynthesis or respiration can be read directly from the recorders. This feature is invaluable for obtaining thenecessary data for designing experiments where certain optimum conditions are required. Trap ‘c’ is used to introduce the14CO2 at the end ofa run. The constant head device in ‘F’ and ‘G’ enabled one setting of the screw clamp ‘f’ to maintain the flow constant throughout a run. Theballoon ‘K’ is filled through stopcock ‘.’ The tube from ‘F’ to ‘G’ is clamped off and the water is run out of ‘G’ pulling air from ‘J’ into ‘G’which pulls the balloon open sucking CO2-free air into ‘K.’ The14CO2 is added via trap ‘m’. Since 0.003% CO2 was being handled, and sinceit was important that its specific activity be maintained, a soda-lime absorber was placed between ‘G’ and ‘J’. This absorber was considerednecessary in the light of the solubility of CO2 in rubber. At first much trouble was encountered with the balloon bursting while it was beingevacuated, but this problem was solved by means of device ‘L’ which is a small perforated glass bulb through which the gases are removedfrom the balloon. The many holes and irregular shape of this glass bulb prevent the outlet from being blocked by the collapsed balloon beforethe balloon is completely empty. Samples representative of the algal suspension can be taken by turning the stopcock on the illumination vesselin a clockwise direction. The figure and the legend are essentially reprinted from Wilson and Calvin (1955), by the permission of the AmericanChemical Society.

thesis. Calvin’s autobiography,Following the Trail ofLight (Calvin 1992), represents an extremely singularview of the research carried on in the laboratory par-ticularly in the area of the path of carbon for whichhe received the Nobel Prize. In all the 175 pages ofhis autobiography there is not one sign of Andy Ben-son or a mention of him. There is not one picture ofAndy in a book that contains 51 photographs rangingfrom graduate students to the King of Sweden. Thereis not the citation of a single paper with Benson as

an author or co-author in an extensive bibliography ofover 150 references. Benson’s name appears nowherein the text and consequently is absent in the 12-pageindex. This appears to be an undeserved slight to agreat scientist both personally and professionally whohad contributed in a major way to all of Calvin’s re-search and technology in the field of photosynthesis.Andy was a real leader in the laboratory both intel-lectually and experimentally. He should have been apartner in The Nobel Prize. Al Bassham’s contribu-

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tions are also understated, although he is pictured andcited through the text. I know that all of us who werecolleagues at Berkeley agree that it was Andy andAl who contributed greatly to our own success in fu-ture endeavors. I have no idea what may have causedthis unfortunate event, but I think that history shouldrecord that the contribution of Andy Benson is notproperly recognized in Calvin’s autobiography.

My immediate task upon arriving in Berkeley, be-sides cleaning up algal cultures, plunged me intothe path of carbon experiments; these included theexamination of other photosynthetic microorganisms(besides algae). Working closely with Al Bassham andAndy Benson, I learned the14C labeling, chroma-tography and radioautograhy technology. By the lateforties, Andy and Melvin (Calvin and Benson 1948)had pretty well established that 3-phosphoglycericacid (PGA) was an early (<5 s) CO2 fixation product.In addition the four-carbon acids of the Krebs cyclewere labeled heavily with14C when algal cells werepre-illuminated and then exposed to14CO2 in the dark.Benson suggested that during pre-illumination exper-iments inChlorella, light produced reducing powerin the form of NADPH or NADH accounting for theformation of malate, succinate, and citrate after thelight was turned off. PGA was also formed, but its syn-thesis greatly increased with continuous exposure tolight during14CO2 fixation (Benson and Calvin 1947).In 1939 Robin Hill at Cambridge University demon-strated the light-dependent evolution of O2 from isol-ated chloroplasts, now known as the Hill reaction (Hill1939). So, by the late forties O2 evolution and NADPreduction were known to be involved in carboxyla-tions in both oxidation reactions and photosynthesis.Andy Benson had always strongly stressed the im-portance of the synthesis of sugar monophosphatesand diphosphates during the photosynthetic reductionof CO2. Professor Arnold Nordal, an expert on se-doheptulose (C-7) and related sugars had arrived atthe lab from Norway. Severo Ochoa (1948), HarlandWood (1946) and others worked on respiratory reduc-tive carboxylations. Transkelotase and transaldolaseenzyme reactions had been clarified in the synthesismechanisms of C-5 and C-7 sugar phosphates. MartinGibbs and colleagues at Brookhaven National Labor-atories observed the asymmetric labeling of the sugarphosphates in short-term photosynthesis (Horecker etal. 1954; Gibbs 1996). As a result of these elegant butpuzzling results, Calvin suggested the following: thatβ-carboxylation of RUBP could yield an unstable six-carbonβ-keto acid as an intermediate; and that this

acid, when hydrolyzed, spontaneously split into twomolecules of PGA with the primary14CO2 labelingtheβ position of the six-carbon unstable intermediate.His chemical deductions were simply brilliant. Thiscarboxylation at theβ position of ribulose formed thebasis of the asymmetric14C labeling in the formationof the sugar phosphates. The missing link – of theelusive two-carbon acceptor – proved to be the toptwo carbons of RUBP. In other words Calvin’s newcarboxylation turned out to be C1+ C5 = C6÷2 = 2three-carbon PGAs as shown in Figure 4.

From that point on, the reductive pentose phos-phate or Calvin Cycle fell together. The path of carbonwas solved thanks to the interdisciplinary staff, vis-itors, and students, led by both Andy and Al and ofcourse Melvin’s leadership (Calvin et al. 1954).

Melvin received the 1961 Nobel Prize in Chem-istry for the above work. Later he received an invita-tion to the White House. As a gesture of recognitionto Nobel Prize winners, President John F. Kennedy,and his wife Jackie, wined and dined the current aswell as past American Laureates including Ed Tatumand Melvin together with his wife, Genevieve. Thisevent inspired Kennedy’s now famous quote: “this isthe most extraordinary collection of talent and humanknowledge gathered at the White House, with the pos-sible exception of when Thomas Jefferson dined herealone.”

J. Rodney Quayle (Rod) had joined Melvin’s labin 1953 as a visiting scientist. Rod and the restof us collaborated with Andy on the firstin vitrodemonstration of RUBP carboxylase enzyme in a cell-free system (Quayle et al. 1954). This system wascrude. No source of ribulose 1,5-bisphosphate for asubstrate existed, only having been characterized asa ‘radioactive spot’ on paper chromatograms. How-ever, by eluting enough of these spots from paperchromatograms, we did isolate enough of the pro-posed substrate to carry out a cell-free enzyme assaywith 14CO2. The radioautograph of that experimentshowed one major compound,14C-labeled PGA. Thedata demonstrated the first evidence of anin vitroenzymatic reaction of the ribulose 1,5-bisphosphatecarboxylase. In all fairness, Weisbach, Smyrniotis andHorecker substantiated our conclusion. In their pa-per published in the same issue of theJournal of theAmerican Chemical Society, Weisbach et al. (1954)showed a carboxylation using ribose-5-PO4(R5P) asa substrate and demonstrated that a soluble extract ofspinach leaves carried out a carboxylation that formeda carboxy14C-labeled PGA. This preparation, how-

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ever, was a ‘multienzyme’ system. The reaction alsorequired energy and reducing-power in the form ofATP and NADPH. In retrospect we know that theseauthors had missed the CO2 fixation reaction mechan-ism by two enzymatic steps – a phosphorylation andan epimerase reaction that yielded RUBP from ribose5-phosphate, then followed by the carboxylation.

However, a few less than impressive events alsooccurred during my stay at Melvin’s lab. Andy Bensonchronicled one such event in 1995. Since his note sowonderfully describes life in that lab and involved me,I quote it at length (Benson 1995):

Saga of a great theory of photosynthesis

“The most exciting idea which I and many ofmy colleagues experienced was Melvin Calvin’s‘Thioctic acid Mechanism of Photosynthesis’, asuperb concatenation of information, ideas and ex-perimental evidence which appeared to fit with allwe knew of photochemical energy conversion inthe chloroplast. It developed at the time thiocticacid (lipoic acid) and its function had just been dis-covered. It is a yellow compound, with the properabsorption at 330 mµ to accept the energy froman excited chlorophyll molecule. Melvin Calvinand G.N. Lewis were highly respected in photo-chemical circles and the absorption of energy bythioctic acid seemed logical. The product, a dithiylradical [R–S...S–R] was consistent with the pleth-ora of sulfur radicals detected in photosynthetictissues with the then-novel paramagnetic reson-ance spectrometers. John Barltrop, who had comefrom Oxford University’s chemistry department,proceeded to develop experimental support for thetheory. He and Calvin collected convincing evid-ence for the reaction of such radicals with water oralcohols. Thus photolysis of the strained disulfidering could yield both R-SH and R-SOH, a sulf-enic acid, on the same thioctic molecule. One, areducing agent, and the other, a sulfur analog ofan alkyl hydroperoxide capable of yielding oxy-gen. Thus the energy of the quantum absorbed bychlorophyll could yield the chemical essentials ofphotosynthesis.

Finally, Balthrop and Calvin tested the hypo-thesis in Scenedesmus treated with added thiocticacid; oxygen production increased 50%. Theplausibility of the theory was elegantly developedin over forty pages of ensuing publications doc-umenting the experimental evidence. Had Nature

overlooked this opportunity it would have made amistake. The quality of the research was superb,as one can appreciate from the meticulous publica-tions. For a year the whole effort was exhilarating.It was truly a Nobel idea.

The high point of this saga was Melvin’s lecturein a 1954 national meeting in San Francisco. Be-ginning with his usual hesitant manner and leadingto a magnificent crescendo of convincing evid-ence for the mechanism of the quantum conversionof photosynthesis, the audience was totally im-pressed. The great C.B. van Neil jumped from hisseat in the front row with tears in his eyes to con-gratulate Melvin. It seemed a consummation ofhis own decades of thought and effort dedicatedto understanding photosynthesis.

Final proof lay in identification of thioctic acidin the chloroplast; but the assay was tedious andrequired microbiological experience. Clint Fuller,with a new PhD from the Stanford laboratoryof Beadle and Tatum, was recruited to assaythioctic acid. I grew someChlorella in sulfate-S35, chromatographed the extract and prepared theradioautograph of my paper chromatogram. WithMelvin and the others standing around the greatwhite table, I laid the film on the paper. There, wasa huge black spot, right in the position we expec-ted. Melvin’s eyes just about dropped out onto thefilm. It was a breathtaking moment.

The S35 radioactivity had to be proved to bethioctic acid. Try as he would, Clint Fuller andhis Streptococcus fecaelisbacterial assay couldn’tfind a trace of thioctic acid that coincided withthe radioactive35S spot. One by one, the evid-ence for the several critical steps weakened andthe thioctic theory quietly evaporated. The massiveeffort, the elegant chemistry and photochemistryproduced impressive publications which no longerattract attention. Yes, the theory was in ashes butwe must see a ‘take home lesson’ in this saga. Onecan survive a failed effort; even one which hadinvolved man-years of work and excitement.”

We all learned.At this time Andre O.M. Stoppani, a visitor from

Argentina, joined Calvin’s lab. Andre was a micro-biologist who later became President of the Argen-tinian Academy of Science. His presence gave usall the opportunity to begin working on the path ofcarbon in prokaryotic photosynthetic bacteria. Thepresence of Roger Stanier and Mike Doudoroff, previ-

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ous PhD students of van Niel at Stanford and membersof the Microbiology Department at Berkeley, furtherreinforced our interest. How the prokaryotic organ-ism managed and coordinated energy capture, ATPproduction, pyridine nucleotide reduction and CO2fixation in the unstructured, non-compartmentalizedprokaryotic cell was not known.

Daniel I. Arnon and his collaborators had demon-strated that all of these processes took place in theeukaryotic chloroplast, structurally segregated fromrespiratory and other biosynthetic activities of the cell.We wanted to investigate the organization of theseprocesses in prokaryotic systems and determine thestructures that exist for the separation of the com-peting respiratory as well as synthetic metabolism.We published several papers, referred to in the nextsection, on our findings. Although we gathered inter-esting information on the cellular biochemistry in bothRhodopseudomonasandChromatium(Stoppani et al.1955), it had become clear that this research would notremain part of the Calvin mission in the long run.

In running his lab, Melvin had a not particularlysubtle, yet gentle, way for separating personnel fromthe group. For instance, he would call me into hisoffice and tell me that he had recommended me topresent a seminar at ‘x’ or ‘y’ academic institutionsince he was unable to go. I gave several of theseseminars in 1954 and even received job offers at someless than exciting places. With no forewarning, I heardabout the job possibilities only after my arrivals at thevarious institutions. In the fall of that year, I again re-sponded to a call from Melvin’s office, expecting moreof the same. But he inadvertently presented me with areal opportunity this time. Melvin had been invited byThe American Society of Plant Physiologists to givea symposium paper at their annual meeting to be heldin Gainesville, Florida. Due to what he called ‘previ-ous commitments’, Melvin now could not attend themeeting. However, he already had submitted an ab-stract, co-authored collectively by me, Andy and RodQuayle, to be presented at the meeting. Well, none ofus had been aware of such a submission! Pointing outthe ‘good exposure’ for me, he asked if I could go inhis place! Clearly, pressure for my independence wasgrowing; I jumped at the chance. Then the very humanside of Melvin emerged. “Clint”, he asked, “doesn’tyour family live back East, and wouldn’t you like tovisit them on the way home?” I suggested that de-touring to Providence, Rhode Island on my way fromFlorida to Berkeley would be a pretty expensive di-vergence. Reflecting, he suggested sending me, with

all expenses paid, to Brookhaven National Laboratory(BNL) on Long Island; after my stay as a consultantthere, I could visit my parents on my way home. Afterwe remembered that Martin (Marty) Gibbs who wasworking on asymmetric14C labeling and degredationof sugars in photosynthetic14CO2 fixation was there,Melvin said that he could arrange everything.

So I attended the meeting of the American Societyof Plant Physiologists in Gainesville and continued onto BNL. I gave my seminar there and met with MartinGibbs for a lengthy conversation about the path of car-bon. On that evening some of the staff joined me for aterrific Atlantic seafood dinner; this social event wouldinfluence my future plans. On the next morning, Martyinformed me that the Chair of the Biology Divisionwanted to talk with me about an available position fora plant biochemist. Howard Curtis, the Chair, and Ihad a long, very memorable talk. I also recall longdiscussions with Dan and Marian Koshland as well asones with several other plant scientists including Sey-mour Shapiro and Otto Stein whom I eventually wouldfollow to the University of Massachusetts. In differentways at different times in my career each one of theseBNL scientists had a tremendous influence on my ca-reer both at Brookhaven and at future institutions. Allconvinced me that Brookhaven, on both personal andprofessional levels, would be a great place to be in the1950s.

Thanks to the intervention and enthusiasm ofMarty Gibbs, my stay at Brookhaven culminated in ajob offer on the spot. The mid-1950s coincided withexplosive advances in science and wonderful finan-cial support for photosynthesis research. The positionoffered to me was that of plant physiologist on thestaff in the Biology Division of BNL. The job wouldinclude a generous operating budget, equipment asneeded, the salaries for a technician as well as post-doctoral positions and travel expenses. There was noexcuse for not succeeding! Those were the days! Uponreturning to Berkeley, I announced my new job toMelvin who, along with me, had not known that theposition was available. Serendipity again! The fortu-itous job opening certainly coincided with Melvin’sgenerosity in providing a way for me to visit my fam-ily in Rhode Island. His thoughtfulness and Marty’ssupport combined to move me into the next stage ofmy career during an era that would enthusiasticallysupport photosynthesis through government agenciesfor another quarter of a century.

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On my own: Brookhaven National Laboratory,1955–1960

My family increased to five, and still growing, movedback East in March 1955. I set up my lab, andthe facilities were superb. I developed my own re-search program on microbial photosynthesis. WithMarty Gibbs, I started a collaborative project thatresulted in several published papers about the reg-ulation of RUBP carboxylase synthesis in dark andlight-grown Englena. We demonstrated that the en-zyme was synthesized only in the chloroplast oflight-grown chlorophyll-containing cells (Fuller andGibbs 1956, 1959). Specifically, our work showedthe in vivo regulation of enzyme synthesis correlatedwith the structural development of the chloroplast.During the previous summers, Marty had collabor-ated with several visiting scientists including BernieHorecker, Irwin Gunsalus and others who had studiedboth the enzymes of sugar biosynthesis and the assy-metric 14CO2 label of sugars (Gibbs 1996). JoiningMarty’s group for a year, Otto Kandler, the well-known microbiologist from Munich, expanded uponthe degredation studies of14CO2 fixation products.Our lab work taught us all a great deal about mi-crobiology and enzymology. Post-docs and visitingscientists also began to appear in my own lab. StuartTannenbaum, with a PhD directed by David Sheminat Columbia and a post-doc with Tatum while I was atStanford, spent several summers with me. Bob Smil-lie, from Canada and Australia, Irwin Anderson, JohnBergeron and Sam Conti were among the outstand-ing post-docs who worked with me at BNL. I wasfortunate enough not only to start in-depth studies onthe comparative biochemistry of the carboxylase sys-tem (Smillie and Fuller 1959) but also research on thestructure of the photochemical apparatus of a varietyof photosynthetic microbes.

At this time the consortium of universities whichoperated Brookhaven National Laboratory allowedsabbatical leaves. Thanks to Rod Quayle and HansKornberg, associates from my days in Calvin’s lab, Ireceived an invitation from Professor Sir Hans Krebsto spend a year in Oxford. The National ScienceFoundation awarded me a Senior Research Fellow-ship. (Five years beyond the PhD turned one into a‘Senior.’) Thus I and my family, now increased to sixmembers, arrived in Oxford during the fall of 1960.Our new home belonged to Oriel College and was builtin the 13th century. Serving as a hospital for lepersat one time, the house stood just outside the walls of

Oxford. It was absolutely charming even though thelack of central heat guaranteed some chilly days andnights.

At Oxford I worked closely with Hans Kornberg,studying photosynthetic CO2 fixation in the obligateanaerobic bacteriumChromatium vinosum(Fuller etal. 1961). My own work with Stoppani at Berkeley andBrookhaven had shown that Krebs cycle intermediates(Stoppani 1955), particularly malate and succinate,were labeled heavily by14CO2 in bothRhodopseudo-monasand Chromatiumat very short times. BothKrebs and Kornberg suggested that we examine theenzymes of this obligate anaerobe to see if these en-zymes might be involved only in the protein and/orfatty acid synthesis rather than the energy-generatingcitric acid cycle. That the RUBP carboxylase was theinitial photosynthetic CO2 fixation enzyme in sev-eral species of purple photosynthetic bacteria hadbeen demonstrated earlier by us (as referenced above).Early experiments at Oxford had indicated an appar-ent absence of both malic acid dehydrogenase andα-ketoglutaric acid dehydrogenase. By the time ofmy sabbatical at Oxford, Krebs had described the cit-ric acid cycle as the major source of ATP, throughoxidative phosphorylation. He mostly worked with pi-geon heart miochondria. Krebs thought that all cellsmust contain these two enzymes for their roles inbiosynthesis as well as oxidative energy production.

Krebs simply did not believe that my data showedthat the purple bacteria, even being obligate anaerobesdependent on photophosphorylation, could synthesizethe necessary bacteriochlorophyll without these en-zymes. Wanting to watch me do the experiment, Krebspronounced, “Clint, there must be some error in yourtechniques.” The assays for these two enzymes werecarried out spectrophotometrically on the then newCary model 11 spectrophotometer. I made up cell-free preparations ofChromatiumandRhodospirillumrubrum. The latter, capable of growing aerobically inthe dark through the use of an intact citric acid cycle,functioned as a positive control for these two missingenzymes. Using a cuvette with oxaloacetate as the sub-strate, NADH and buffer provided the assay for malicacid dehydrogenase. WithR. rubrumas the control,the malic dehydrogenase source would reduce the ox-alic acid to malate with the concurrent oxidation ofNADH to NAD and the loss of its absorption in the ul-traviolet. With Krebs and Kornberg watching over myshoulder, I added a drop of the cell-freeChromatiumextract to the cuvette. No change occurred in opticaldensity. Nothing happened to indicate the presence of

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malic dehydrogenase activity. Then I added a similaramount of identically prepared extract of theR. rub-rum (containing the identical amount of protein) to thesame cuvette. In 10 s the NADH was oxidized. In thisway Krebs and Kornberg became reluctant believersof my data.

However, Howard Gest and J.T. Beatty laterdemonstrated that the missing two enzymes actuallydid exist in Chromatium (Beatty and Gest 1981).Because of their tight binding to the cytoplasmicmembrane particles, both enzymes in my Oxford ex-periments, apparently, had been spun out in the cent-rifugation of the enzyme preparation. So much forpremature speculation lacking the proper controls suchas looking for activity in all the cell factions. My onlyexcuse might be that photosynthetic prokaryotes, interms of cell biology as well as membrane-bound en-zyme activity in both photosynthesis and respiration,involved a relatively unknown area of science in 1960.Today we know that the difference betweenChroma-tium andR. rubrumcould well be a simple variationin the density of the two cytoplasmic membranes. Inmy case, failed efforts become paths of learning. I waspushed onto newer and even more exciting areas.

A diversion to medical education: 1961–1968

Ending my Oxford sabbatical, I accepted a position atDartmouth Medical School as Chair of a new Depart-ment of Microbiology. Marsh Tenney, the Dean anda distinguished mammalian physiologist, hired me.Primarily, I accepted the position because of the out-standing cast of characters hired by him to rebuild theMedical School. Shinya Inoue, a cell biologist fromPrinceton, headed cytology and anatomy. Inoue hadhired Kenneth Cooper and Andrew Szent-Gyorgi. Bio-chemistry, originally headed by Manuel Morales, hadhired Melvin Simpson, Peter von Hippel, Ed West-head, Lucille Smith, Walter Englander and LafayetteNoda. Kurt Benirschke, a distinguished cytogeneticist,headed the Pathology Department. From The Mas-sachusetts Institute of Technology, Walter Stockmeyerhad just arrived to chair the Chemistry Department inthe college. As of yet the Microbiology Departmenthad not been developed. During the decision-makingtime, I was concerned that I neither had much aca-demic or administrative experience nor was working ina research area directly related to medical education. Iasked Marsh if he had any reservations about an inex-perienced 35-year-old, who worked in photosynthesis.

After all no one ever died of photosynthesis! Glaringat me, he replied, “How old do you think I am?” (Hewas 39!). Marsh was interested in hiring outstandingbasic scientists who were oriented towards researchand capable of interacting with the college sciencefaculties at the undergraduate level to develop a med-ical and premedical program of distinction. He wantedme to do the same for the Microbiology Department,and I did. I hired S.F. Conti, a real microbiologistfrom Cornell who also had been a post-doc with me atBNL. I also recruited Lawrence Kilham, a senior med-ical virologist from the National Institutes of Health(NIH). Already at Dartmouth, Philip O. Nice, whohad real experience in medical microbiology, togetherwith several younger associates completed the team.These scholars well complemented the undergraduatebiology department as well as the medical school’s de-partments of Biochemistry and Cytology. Our work onphotosynthetic prokaryotes flourished.

Visitors to my lab included David Hughes ini-tially from Oxford and then from Cardiff Universityin Wales where he was Professor of Microbiology(Hughes et al. 1963). Rod Clayton arrived to take askiing and science sabbatical with us. From my laband that of Sam Conti, post-docs initiated our jointwork onR. rubrumand the green photosynthetic bac-teria; they included Louise Anderson (Anderson andFuller 1967a–d; Anderson et al. 1968), Stanley Holt(Holt et al. 1966; Holt and Fuller 1966), ElisabethGantt and Sam Conti (Gantt and Conti 1965, 1966).While we studied photosynthetic prokaryotes, those inSam’s lab worked on the structure of the photosyn-thetic apparatus of the eukaryotic red algae as well asthe prokaryote cyanobacteria.

During the period I was at Dartmouth importantresearch carried out by Jessup Shively at ClemsonUniversity had a major impact on our knowledge ofthe structure, assembly and function of the RUBPcarboxylase enzyme in photosynthetic prokaryotes.Started in the 1960s, this research was pursued duringthe decade, and led to the discovery of the carboxy-some – a prokaryotic cellular inclusion consisting ofthe enzyme and six other proteins. The photochemicalapparatus and photochemical electron transport sys-tem were organized inside the cell on the lipoproteinbilayered cytoplasmic membrane. The carboxysomewas organized as a paracrystaline array of the enzymeand six glycoproteins and attached to the cytoplas-mic membrane by the small subunit peptide of theRUBP carboxylase. This protein assembly in proka-ryotes allows for rapid mobilization and regulation for

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photosynthetic carbon dioxide fixation and subsequentcarbon metabolism (Shively et al. 1988).

Interactions with Otto Warburg

During my stay at Dartmouth, another historically in-teresting event took place in photosynthetic research.The event involved Otto Warburg, the physician andgiant of German biochemistry who had won a No-bel Prize in Physiology and Medicine in 1931. Healso won a second Nobel Prize in 1944; however anorder from Hitler intervened which forbade the accept-ance by Germans of the Prize. Warburg belonged toa Jewish family, that had attained wealth and famein the field of banking and the support of art as wellas distinction in the fields of medicine and science.His father (Emil Warburg) was a famous physicistwho was a Professor at Freiburg and Berlin. Althoughmost of his family escaped from the Nazis during the1930s and established their banking empire in Lon-don, Otto Warburg remained in Germany as head ofthe Kaiser Wilhelm Institute (changed after the war tothe Max Planck Institute at Berlin-Dahlem). It is ofhistorical interest to note that Warburg was not har-assed personally or professionally by the Nazis. Onereason was that his mother’s family was not Jewishwhich made him only one half Jewish. Another reasonwas that Reichsmarshall Goering had made a declar-ation that “I decide who is a Jew” and arranged fora reexamination of Warburg’s ancestry and ruled thathe was only a quarter-Jew. During the war years an-other highly placed Nazi Reichsleiter Bouhler, Chiefof Hitler’s chancellery, personally protected Warburgwhen he was indeed critical of the regime. Warburg’swillingness to let his Jewish blood be diluted and thusmake a pact with the Nazis incensed both his familyin England and his colleagues outside Germany. It isalso worthy to note that both Hitler and Goering werehypochondriacs and terrified of cancer. Warburg wassure that his oxidation-reduction research was goingto lead to a cure for cancer, a thought that he promotedwidely. The above information, including the involve-ment of the Nazi hierarchy in Warburg’s safety, is welldocumented by Professor Sir Hans Krebs in his bio-graphy of Warburg (Krebs 1981). Krebs spent 4 yearsas an associate of Warburg in Berlin before escapingto England (he was 100% Jewish). Krebs passed thisinformation on to me personally as well as to others,prior to his publication of the biography while I wasspending a year’s sabbatical with him at Oxford.

After World War II, Warburg visited the UnitedStates, at the invitation of Robert Emerson and EugeneRabinowitch at the University of Illinois (see Figure5). Warburg was disputing the quantum requirementof photosynthetic O2 evolution as observed by RobertEmerson and Carleton Lewis (1943a,b) and WilliamArnold (1949). In essence their disagreement boileddown to whether photosynthetic O2 evolution requiredonly three to four quanta of light or the eight to 12quanta clearly demonstrated by Emerson, Arnold andothers. Lasting for years, this difference in opinionnever became completely resolved. Govindjee (1999)has reviewed this controversy and its background inan article for the Historical Corner in PhotosynthesisResearch; he explained the dilemma with a fascinat-ing analysis of the Emerson and Arnold experimentsversus the ones by Warburg. The dream of photo-synthesis being perfect in nature and 100% energy-efficient drove Warburg. Of course, like everythingelse in nature, photosynthesis neither was nor is per-fect.

That Warburg had a brilliant mind and intellect andwas experimentally creative no one can deny. It washis conclusions not his experiments that created thegreat controversy. The distinguished biochemist Eph-raim Racker (Racker 1972) stated this contradiction inWarburg’s research. “Few will challenge the statementthat Warburg was one of the great biochemists. His ex-perimental approach was monumental and ingenious.Yet Warburg’s views on two vital areas of his researchinterests, cancer and photosynthesis, are now almostuniversally dismissed as erroneous and naive.”

I became involved with a Warburg controversy inphotosynthesis research in the area of CO2 fixationand the RUBP carboxylasein vitro and in vivo en-zymatic experiments carried out by myself, MartyGibbs, Andy Benson and our associates from 1954 to1964. Warburg’s interpretation of his results involveda hypothetical chemical reaction of carbonic acid withchlorophyll to form a complex that he referred to as‘phytolyte’. This complex required the oxidation ofreduced carbohydate from respiration to form carbonicacid and the subsequent ‘carboxylation’ of chlorophyllto yield O2 and reduced carbon; this process only re-quired a low quantum requirementof 3 according tohis results and calculations. This, of course did notagree with all the path of carbon research from thelaboratories of Calvin and his associates on both theRUBP carboxylase system and the formation of PGAas the primary reduced fixation product from carbondioxide.

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Figure 4. The reaction mechanism for the primary carboxylation and the formation of phosphoglyceric acid (see text).

In 1965 Andy Benson and I each received a let-ter from the Max Planck Institute in Berlin. (While Iwas educating Dartmouth medical students about en-ergetics, Andy had gone to the University of CaliforniaMarine Biology Laboratory in La Jolla.) My letter sa-luted me as ‘Dear Professor Benson’ and invited Andyto be a discussant of Warburg’s symposium paper at ajoint meeting among the Swiss, French and GermanBiochemical Societies to be held in Strasbourg. ButWarburg’s enclosed personal check for 4000 Deutch-marks was written out tome. When I got on the phoneto Andy, he told me that his letter had accompanied acheck for him, but the invitation had greeted ProfessorFuller. In any case Warburg seemed to mix up a lotof things in addition to quantum requirements for O2evolution and CO2 fixation in photosynthesis. I stillhave a photocopy of that check in fond memory ofa great man who could be so very wrong. We sub-sequently found out that a third American scientist,Harlan Wood at Western Reserve University also hadbeen invited. When we discussed the situation amongourselves, all of us expressed puzzlement over beingchosen and some discomfort with what ‘discussing’Warburg’s presentation might mean. Nonetheless, weaccepted, hoping that the Biochemical Societies wouldknow what was going on.

Since 4000 Deutsch marks equaled about $1000 inthose days, I was able to take my wife and enjoy a

vacation with her after the Warburg symposium. WhenAndy, Harlan Wood and I arrived in Strasbourg, wereceived a note to us from Professor Helmut Holzer, awell-known biochemist from Freiburg who would bechairing the meeting on the following morning. Hisnote directed us each to speak for 30 min after War-burg had made a presentation for an hour. We werestill in the dark. Assuming that Warburg knew verywell that all of our data and ideas completely con-tradicted his own, we had no idea what he expected.So we asked Professor Holzer what was going on. Heexplained that the symposium was to be a “HangingParty, as you Americans say.” In July of 1962 War-burg had attended a meeting in Gif-sur-Yvette, France,where he had expounded on his ‘photolyte’ hypo-thesis. (Warburg 1963). At the meeting, Calvin hadresponded to Warburg’s talk with unusual restraint bysimply sitting on his hands – in silence. Warburg hadinterpreted this reaction as an act of submission! Asfollowers of the Calvin CO2 fixation cycle, we threewere to surrender publicly (I assumed) to Warburg inour discussions of his paper. Professor Holzer knew, ofcourse, what we actually would do. Returning homethat night, we all were very glad that we had cashedthose checks!

The Warburg symposium was quite an event. Onthe following morning, most of the attendees waitedon the steps of the convention hall to greet Warburg

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Figure 5. Photograph of the Nobel laureate Otto Warburg in RobertEmerson’s Laboratory at the University of Illinois taken in 1948.Standing with him is the then Assistant Professor of Botany atIllinois, Dr. Oswald Tippo who later became Chancellor of the Uni-versity of Massachusetts at Amherst. In 1971 he hired the author ofthis Perspective as the Head of the Biochemistry Department at thatinstitution.

upon his arrival. His long, black Mercedes-Benz witha license plate reading MP-B1 (Max Planck–BerlinOne!) pulled up, and a liveried chauffeur openedthe passenger door. Warburg stepped out wearing asuit, tie and 10-gallon Cowboy hat (perhaps from hisIllinois days in the 1940s?). Jacob Heiss, his constantcompanion since World War I, scientific associate,laboratory manager and cook (Krebs 1981) followedhim. The three of us discussants each were introduced.Looking me up and down, he shook my hand and ex-claimed, “Herr Fuller, you are much too young!” Acomplement, I assumed!

His paper presented nothing new, simply the pho-tolyte story with three to four quantum requirement,carbonic acid from respiration and O2 evolution, allresulting from the ‘carboxylation’ of chlorophyll. Asfirst discussant, Andy followed Warburg, giving a

scholarly and elegant presentation of the whole pathof carbon story from PGA through the Calvin cycleusing radioactive14CO2 tracer. Warburg had rejectedall the work that used isotopes as artifacts. FollowingAndy, I presented my work on the RUBP carboxylaseenzyme including the regulation of its synthesis inprokaryotes and eukaryotic chloroplasts along with itsabsence in organisms containing none of the structuralcomponents of the phtosynthetic or the autrotrophicbacteria. Both Andy and I simply ignored Warburg’spresentation. Harland Wood, however, did not. He wasthe world expert in the biochemistry and chemistryof carboxylation reaction mechanisms. Later Harlandwould discover the role of biotin in these types of reac-tions in mammalian and microbial systems. Presentingconvincing descriptions of the biochemical and chem-ical mechanisms, Harland ended his talk with the fol-lowing remark:“Professor Warburg, I have presenteda review of carboxylation mechanisms. From studyingall such reactions known in biochemistry, and manypossible ones in chemistry, I know of no known mech-anism that would support your photolyte hypothesis.”Then he sat down. This was no hanging party forus Americans! After the symposium not a word wasspoken about the path of carbon. Warburg and themayor of Strasbourg hosted an elaborate dinner andreception. In fact Warburg invited the three of us tohis Institute in Berlin. Although my wife and I tookoff for a short holiday in Switzerland, Andy did visitthe Institute. I assume that he became educated onthe necessity of growingChlorella in the light froma North-facing window in the lab and on the use ofangle-held centrifuges to spin out the cells in order torepeat Warburg’s experiments. Warburg, as Govindjee(1999) has pointed out, never did surrender. He died in1970.

A transition

In 1966 I, along with three other department headsand many of the basic science faculty, left Dartmouth.The mass departures resulted from academic and, in-evitably, political reasons. Since the story is long andcomplicated, I will not go into many details here.In short we molecular biologists not only had raiseda lot of grant money but also had started a vigor-ous PhD program. We also were proceeding rapidly(too rapidly for the college administration) towardsestablishing a basic science medical program whichwas right on the cutting edge and should have metMarsh Tenny’s early expectations. Our work, I believe,

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played an important role in how Dartmouth MedicalSchool evolved into the 4-year top-notch medical, re-search and teaching center for central New Englandthat distinguishes it today. The event leading to ourdeparture is a rather poignant, and somewhat amus-ing, example of academic disagreement. Sixteen ofus (all full Professors) had written a proposal for thedevelopment of graduate programs that would form agraduate school, or its equivalent, for our Molecularand Cellular Biology PhD program; our proposal alsoincluded the appointment of a graduate Dean, insteadof the Medical School Dean, for this program. Aftersending our proposal to the President, John Dickey,we asked for a meeting with him. Our meeting tookplace just before Christmas in 1965. We had del-egated Andrew Szent-Georgyi as our advocate sincehe presented himself as being soft-spoken and cool-headed. I, on the other hand, had been ordered tokeep my mouth shut despite my position as PrincipalInvestigator of a large NIH Training Grant that hadbeen awarded to run our proposed program. But Iagreed happily and let Andrew do the talking. Pres-ident Dickey told us that he, indeed, had read ourproposal, which he called the ‘Fuller document’. Icringed but didn’t say a word. After some discussion,the exasperated-looking President gave us our answer.“Lady and Gentlemen”, he began referring to Pro-fessor Lucille Smith and the rest of us, “Dartmouthis about to enter its third century. It has gotten alongvery well for the past 200 years without Molecularand Cellular Biology, and I perceive it doing verywell in its third century with or without Molecular andCell Biology. Good evening and Merry Christmas.”On the way out, Shinya Inuoe quietly remarked thatwe really hadn’t expected any presents this Christmas.Despite this last instance, my Dartmouth years werea positive personal and professional time. Microbialphotosynthesis flourished.

An event that occurred in Calvin’s scientific travelshappened a number of years after I had left Berkeleyand was on the faculty of Dartmouth Medical School.It was so typical of Melvin’s quick mind and wit,topped with his inevitable dash of arrogance, that itis worth repeating here as it was heard by hundredsbut as far as I can determine was never noted in print.

The year was 1963 and Melvin had been asked togive a Sigma Xi lecture at my old Alma Mater Am-herst College. George Kidder my mentor at Amherstasked me down from Hanover to Amherst for the lec-ture and associated festivities. The lecture was titled‘Chemical Evolution and the Origin of Life’ an area

of interest to Calvin for a long time and lately a sub-ject of research in the laboratory. The talk was to begiven in Johnson Chapel a late 18th century churchon the campus that was also used as a lecture hall fordistinguished visitors. It was a convincing exposition.He described his work and that of others in the field,that organic acids, amino acids as well as pyrimidinesand purines could be formed when an artificial en-vironment of methane, nitrogen, ammonia and waterwere exposed to an electric discharge. There was aquestion period and a gentleman dressed in clericalcloth stood up and congratulated Melvin for his su-perb and convincing lecture. He continued: “ProfessorCalvin you have told us how living processes and lifeitself could start from these simple chemicals on theprimitive Earth but please tell us what have you leftfor God to do?” Without a moments hesitation Calvinreplied “God sent me here to tell you about it.” A trueProphet! It brought down the house.

Oak Ridge National Laboratory (ORNL):1967–1971

Later becoming the Department of Energy, the USAtomic Energy Commission (AEC) was the governingbody of the USAEC National Laboratories in the mid1960s. I had worked at two of these institutions: theBerkeley Radiation Lab at the University of Californiaand Brookhaven National Laboratory. In 1967 I wasoffered a position as the director of a new enterprisethat would become the University of Tennessee-OakRidge Graduate School of Biomedical Sciences. Thisnew and unique educational development happenedafter an annual scientific review meeting hosted bythe AEC. The US Atomic Energy Commissioners, theheads of various Divisions of the ORNL and senior ad-ministrators from the University of Tennessee (UT) allgathered socially. Dr Dixie Lee Ray, a plant scientistand marine ecologist was the chairperson of the AEC.She later became governor of Washington. In a con-versation with Dr Alvin Weinburg, Director of ORNL,she called all of us working at the National Labs ‘theeunuchs of science’. She meant that we carried out allsorts of research in physics, chemistry and the bio-medical sciences without reproducing ourselves! DrAlex Hollander, Chairman of the Biology Divisionat ORNL, and Dr Andy Holt, President of the UTat Knoxville, also took part in this conversation, thatwould result in the idea of a new graduate school. Inorder to reproduce our knowledge, they came up with

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the concept of the University of Tennessee-Oak RidgeGraduate School of Biomedical Sciences. Using theresearch laboratories and scientific staff of the BiologyDivision ORNL, the school would train PhD graduatestudents for careers in the biomedical or life sciences.Students would be awarded degrees from the Univer-sity of Tennessee at Knoxville. (Though only 20 milesfrom Knoxville, Oak Ridge was hidden away in thefoothills of the Cumberland Mountains for securitypurposes during the war.) In 1967 I was appointedDirector of the new school. We received handsomeappropriation from the Tennessee legislature, gifts ofold military housing in Oak Ridge for the studentsand the funding for several new academic appoint-ments from outside of the Biology Division. I offeredthese positions to Drs Don and Ada Olin, cell biolo-gists from Dartmouth Medical School as well as toDr Frank Hamilton, a microbiologist-geneticist fromPurdue University and the first African-American pro-fessor to have a tenure-track position at UT Knoxville.The four of us were full-time tenured professors at UT.Adjunct professorial positions from the Biology Divi-sion made up the rest of the faculty. Placing a nationallaboratory within the education business at a state uni-versity was a wonderful idea and has been copied atother institutions since then.

Following several distinguished colleagues in pho-tosynthesis research to Oak Ridge also delighted me.The late Ed Tolbert had preceded me at both Berke-ley and Oak Ridge. Bill Arnold, of course, was atOak Ridge when I arrived. He contributed to studieson the concept of the ‘photosynthetic unit’; the max-imum quantum yield of oxygen evolution by calor-imitry; solid state model of photosynthesis; primaryphotochemical reactions at extremely low temper-atures; excitation energy transfer in photosynthesisand emission of light by plants (delayed fluorescenceand thermoluminescence) (see e.g., a special issue ofPhotosynthesis Research honoring his achievements(Govindjee et al. 1996)).

Early on in my stay at ORNL, a memorable mo-ment occurred with Bill Arnold. I was discussing mylove for the simplicity of working with the primitiveGreen Bacteria. Bill paced around his office, clutteredwith years of unopened mail, and ended up at theblackboard. He drew the perfect model for the mech-anism of solar energy conversion to chemical energyas visualized by Bill and remembered by me (seeFigure 6).

Then he exclaimed that I, as a biochemist, onlyneeded to discover how the electron is made available.

I have used his scheme in my teaching for years. Al-though Bill would have been a magnificent teacher,his love for science drove him to pursue a researchcareer. His career enhanced the field of photosynthesisin many ways (Duysens 1996).

Our research lab at Oak Ridge was everything youcould expect at an AEC National Laboratory. Twocolleagues in the Division, Stan Carson and Fred Hart-man, were particularly great as staff members whosupported photosynthesis. While Stan was a formervan Niel student, Fred was a protein biochemist whohelped to unravel the primary and secondary molecu-lar structure of the RUBP carboxylase enzyme. Post-doctoral students and visitors advanced our studies onthe structure and function of the Green PhotosyntheticBacteria. During those years I spent too much time onadministrative duties.

Amherst again: The University of Massachusetts,1971–present

In the spring of 1971, I received an offer from theUniversity of Massachusetts at Amherst to developand chair a new Department of Biochemistry. Bio-chemistry had been sequestered in the Chemistry De-partment of the university since the 1950s; only twoor three professors taught a few courses. No under-graduate major and no graduate program had exis-ted. The biochemists had not flourished there. Thenewly appointed Dean of Science offered a positionto Professor Ed Westhead so that the area of modernbiochemistry at the University would be strengthened.An enzymologist, Ed had trained as a physical pro-tein chemist. He was young but developing a nationalreputation in his area of research. He also was a fellowrefugee of mine from Dartmouth. Before taking theposition, Ed set down the condition that the Universityestablish a new Department of Biochemistry. Whenthe university agreed, he accepted, traveling down theConnecticut River from Hanover, New Hampshire toAmherst Massachusetts. His mission was to recruita new head from outside of the University. Ed likedmy work in microbiology at Dartmouth and wantedme to do the same in biochemistry at Amherst. Fortu-nately the timing was right as I wanted to step downfrom my Deanship at Oak Ridge to a job requiringless administrative duties. Heading a small departmentwith only four to six new positions to fill and havingmore time for research seemed very attractive. As itturned out, I could do more research but could not

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Figure 6. A rendition from a blackboard sketch by William Arnold at the Oak Ridge National Laboratory, given to the author to demonstratethe simplicity of photosynthesis.

leave the administrative functions behind. Serendip-ity again had come into play. Who knows where I,or our research, would have been if Ed had not leftDartmouth for Amherst in 1968. In any case, in thefall of 1971, I again moved to Amherst where 28 yearswould be filled with research, mentoring and teachingin two apparently unrelated fields of research: micro-bial photosynthesis and biomaterials together, creatingfor me an exciting future in microbial biochemistryand polymer chemistry. This perspective will concludeby describing the research carried out by myself andmy colleagues at the University of Massachusetts onthe green photosynthetic bacteria and in the area ofbiomaterials.

The photosynthetic green bacteria

At both Dartmouth and Oak Ridge, I had initiatedwork on the anaerobic green sulphur bacteria, sev-eral species ofChlorobiumand Chloropseudomonasethylicum,a new organism discovered by Elena Kon-dratieva at Moscow State University (Shaposhnikovet al. 1960). Since John Olson (1994) has written indetail about the history and science of this latter organ-ism I will not repeat the information here. Brian Gray,one of my students at Oak Ridge, had demonstratedthat Choropseudomonas ethyliciumwas a symbioticconsortium of a sulfate-reducing anaerobe (Desulfo-vibrio) and Chrobium thiosulfitophilum(Gray et al.1973).

We also had obtained a culture of the newly dis-covered facultative non-sulfur filamentous green bac-teria Chloroflexus aurantiacus. This wonderful new

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discovery gave rise to a whole new family of facultat-ive green bacteria, the Chloroflexiaceae. I feel thatBeverley Pierson, Dick Castenholz and Bill Sistrom,all from Oregon State University at Eugene, derservethe credit for finding this organism. As I interpretBeverley’s elegant description of their work, serendip-ity played a great role in their discovery that actuallystarted in Yellowstone National Park (Pierson andCastenholz 1974; Pierson 1994). On a field trip to thatpark, she found a moderate thermophilic, filament-ous organism which was nicknamed ‘Orange Tuffy’(OT) by her. It was an orange, almost golden-brownorganism. In love with this bug, Beverley proposedto Dick Castenholz that her thesis research be on it.He refused because the project would be too risky anddifficult for her as a graduate student. However, sheprepared a research plan and worked closely with BillSistrom to prove that OT really might be a photosyn-thetic green bacterium. The rest is history. Bill insistedthat Beverley prove that OT had bacteriochlorophyllaas well asc. She did. Dick, as thesis director, enthusi-astically jumped on board. This triumvirate had madehistory by isolating, culturing and characterizing thepigment systems ofChloroflexus. I believe that Bever-ley’s enthusiasm, careful work and creative sciencecombined in her to fit the definition by Louis Pas-teur and Joseph Henry of ‘a carefully prepared mind’capable of receiving and putting together serendipit-ous scientific events (Roberts 1989). That she choseto spend a 1981–1982 sabbatical year in Philip Thorn-ber’s laboratory at the University of California at LosAngeles was no accident. She and Thornber describedin detail the reaction center ofChloroflexus(Piersonand Thornber 1983).

Our research in Amherst onChloroflexusresul-ted in part from Bob Blankenship (Chief Editor ofthis Journal until December 1999), arriving in 1979at the Chemistry Department of Amherst College,our neighboring institution. Across town from eachother, both of our labs shared post-doctoral, gradu-ate and undergraduate students who all worked at firston Chloroflexusand later onHeliobacterium chlorum(Gest and Flavinger 1983). The latter organism weobtained from Howard Gest. He has reviewed the re-search on this organism elsewhere (Gest 1994). Ourconsiderable work with electron microscopy has beenreviewed several times over the years (Sprague andFuller 1990). We also described and characterized indetail the isolated purified photosynthetic apparatus ofChloroflexus aurantiacus. The OT thermophile indeed

Figure 7. The green bacterial chlorosome as described in text. Re-printed from Feick and Fuller (1984), by permission of the authors.© American Chemical Society.

turned out to be a facultative green photosyntheticbacterium.

Our Amherst research covered the spectrum of thephotosynthetic activities of this organism: energy cap-ture; electron transport; carbon metabolism; moleculargenetics; and macromolecular modeling. The joint re-search resulted in over 30 publications; I will note onlya few that depended upon both the North Americanand European laboratories with which we collabor-ated: Blakenship and Fuller 1982; Bruce et al. 1982;Feick et al. 1982; Fuller 1989; Oelze and Fuller 1987;Redlinger et al. 1990; Sprague et al. 1981; Staehlin etal. 1978; Zannoni and Fuller 1988. This work in mylaboratory involved students, post-docs and visitingscientists as well as collaborations with David Knaffin Texas and Davide Zannoni in Bologna, Italy. Twosabbatical leaves from the University of Massachusettsproved that one, indeed, could be intellectually revivedat any age. My visits to the Institut für Mikrobiologieat Freiburg with Gerhart Drews for the year of 1977–1978 and to the Institute für Molecular Biologie atthe Federal Technical University in Zurich with Her-bert Zuber in 1985–1986 opened new avenues for meduring my ‘Chloroflexus years’ (Wechsler et al. 1985).

My research with Reiner Feick, a former PhD stu-dent from the laboratory of Gerhart Drews, and whodid post-doctoral work with me in Amherst, best sum-marizes the above work. Feick’s work culminated withthe development of a macromolecular model of theChloroflexuscellular photosynthetic system shown inFigure 7 (Feick and Fuller 1984).

The importance of this model is that it demon-strates the separation of the antenna bacteriochloro-

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phyll c (Bchl c) structure, the chlorosome, fromthe energy-producing cytoplasmic membrane. All thegreen bacteria contain the chlorosome as a light-harvesting, cellular inclusion. The chlorosome doesnot have the classical membrane structure of a lipopro-tein bilayer as found in all electron transport energy-producing systems that either oxidatively or photo-chemically produce ATP. The lipoprotein bilayer is anessential structure for these latter activities in all euk-aryotes (chloroplasts and mitochondria). In all photo-synthetic prokaryote electron transport, ATP produc-tion occurs either within or across the cytoplasmicmembrane, or on intracellular lipoprotein derivativesfrom them, such as the ‘chromatophore’ membranesystem of the purple bacteria. With a few excep-tions, all non-oxygenic photosynthetic prokaryotesuse bacteriochlophylla as both antenna and reactioncenter pigments. Only the green bacteria have de-veloped the intracellular inclusion containing Bchlcas a primary antenna, shuttling the exited state to theenergy-producing cytoplasmic membrane as depictedby the model presented in Figure 7.

Biomaterials: A new adventure in research –serendipity at its best

Along with the Chemistry and Polymer Science andEngineering Departments, our department had movedinto a new research tower on the campus in 1973.Four elevators, designed to service the laboratories,were controlled by a computer program which musthave been designed in the Neanderthal era. Perhapsmembers of the Mathematics Department, one of thelargest undergraduate departments, suffered the mostsince their department occupied the sixteenth floor.One member, while waiting in the lobby, had enoughtime to calculate that close to 3 months out of the next25 years in his career would be spent waiting for anelevator. The only advantage to cooling our heels inthe lobby was that faculties of different departmentscould get to know each other, both professionally andpersonally.

One of my acquaintances from waiting was Pro-fessor R.W. (Bob) Lenz, a distinguished organic poly-mer chemist. We exchanged information on our areasof research interest; I described microbial and cel-lular photosynthesis while he explained the organicchemistry of polymerization. One day while waitingin the lobby, he told me that the Office of Naval Re-search (ONR) in Washington, DC, had just phonedhim. The ONR, which had supported his research for

years through its Chemistry Division, described to hima new program jointly funded with the Chemistry andMolecular Biology Program. The ensuing conversa-tion between Bob and and myself would prove fateful.“Clint”, he asked rhetorically, “you work with thosecrazy bugs that make polyesters, don’t you?” Doing adouble-take, I replied that out of all the ‘crazy bugs’that had been involved in my research, I knew of notone that could make a polyester, or “material like thischeap shirt I’m wearing”, as I put it. So much formy chemistry! We both laughed. But I was curious.When I asked what kind of polyesters he was workingon, he answered compounds like polyhydroxybutyrate(PHB). I was astonished since I had thought of PHBas a lipid that had been messing up my cell fraction-ation studies inRhodosprillum rubrumfor years. Bobasked me, “What was aRhodospillum rubrum?” Somuch for his microbiology. Bob referred me to theexcellent review by John Anderson and Eddie Dawesfron which I learned both the basics and a great dealabout biopolymers (Anderson and Dawes 1990). Thuswe were launched into a decade of wonderful, excitingand productive collaborative research. On the spot wecomposed a reply to the ONR. We missed the elevatorbut got the grant. The ONR had a long history of sup-porting cutting edge basic research. Kenneth Wynneof the Chemistry program and Michael Marron of theMolecular Biology program deserve credit for sup-porting several groups around the country includingBob Lenz and myself in this new interdisciplinary areaof biomaterials. In 1990, The North Atlantic TreatyOrganization supported the first International Sym-posium on Microbial Polymers which attracted about40 scientists from around the world. The symposiumtakes place every 2 years, and the last one in 1998attracted over 300 participants to its meeting in Japan(Fuller 1999). This new field of endeavor is still on aroll! Serendipity enhanced the science and careers oftwo scientists blessed with open, well trained mindsand slow elevators!

In 1925 at the Institute Pasteur, Lemoigne dis-covered lipid-like inclusions in cells ofBacillus. Inthe following year, he identified these inclusions aspoly-β-hydroxybutyric acid, PHB (Lemoigne 1925,1926) Although only a few successors of Lemoignecarried out research on these PHB inclusions over thenext three decades, Mike Doudoroff and Roger Stanierat Berkeley rediscovered this work in the late fifties(Doudoroff and Stanier 1959). The first biochemical,intracellular studies on these isolated ‘granules’, nowcorrectly referred to as PHA inclusions (Fuller 1990),

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has been reviewed by Joe Merrick (1978). At the Mas-sachusetts Institute of Technology Anthony Sinskyand Oliver Peoples as well as Alex Steinbuchel andHans Schlgel at Göettingen had initiated research onthe molecular genetics and physiology ofAlcaligeneseutrophus(People and Sinsky 1989; Steinbucheel andSchlegel 1991). Bernard Witholt and his associatesinitiated ultrastructural, biosynthetic and moleculargenetic studies usingPseudomonas oleovoransas theexperimental system (Huisman et al. 1992; Lageveenet al. l988). In a most important contribution, thelaboratory group of Douglas Dennis at James MadisonUniversity was the first to demonstrate gene transferand expression of the PHA synthesis genes fromA.eutrophusinto E.coli (Kidwell et al. 1995; Slater et al.1982, 1983).

Over the years research on the biochemistry ofthe PHA synthesis and degredation in a wide varietyof prokaryotes including the photosynthetic bacteriahas slowly emerged. These advances have been re-viewed by Yoshiharu Doi at RIKEN in Japan (Doi1990, 1995). Our own work, starting in 1987, concen-trated primarily on Pseudomonads (Brandl et al. 1988;Foster et al. 1999; Fritzsche et al. 1990a–c; Lenz etal. 1992) as well as on several photosynthetic bacteria:R. rubrum, to Rhodobacter spheroidesandChroma-tium vinosum(Brandl et al. 1988, 1989, 1991). Ourresearch group consisting of up to 30 associates at anyone time, ranging from undergraduates and graduatestudents to post-docs and visiting scientists, completedstudies on both the intra- and extra-enzymatic degred-ation of polyesters (Foster et al 1994, 1996, 1999;Gilmore et al. 1992). With the information gatheredin the last decade or so, we can conclude that PHAsare found in a wide variety of free-living bacteria –never in eukaryotic cells or organisms. These polyes-ters are formed as copolymers with a variety of chainlength repeating units (Doi et al. 1987, 1988). Thepolymers can be ‘functionalized’ by feeding the or-ganisms on carbon substrates containing unsaturateddouble bonds, phenyl groups, etc. (Curley et al. 1996,1997; Hazer et al. 1995; Kim et al. 1991, 1992). Insummary microbial polyesters are biosynthetic, biode-gradable and biocompatible thermoplastic elestomersof great potential for industrial, environmental andmedical use.

My own most recent interest (Griebel et al. 1968)harks back to the studies by Merrick and Doudoroff(1961, 1964). These scientists first showed that isol-ated PHA inclusions were associated with enzymeactivity for the synthesis and degredation of the poly-

Figure 8. The polyhydroxyalkanoate cellular inclusion in Pseudo-monads as described in the text. Reprinted by permission of theauthors (Stuart et al. 1995), and the Canadian Society of Micro-biology.

mer. In our laboratories, the research usingP. oleo-vorans grown on octanoic acid as a substrate hasestablished protein association with the polyester in-clusion. In this system the PHA is a random copolymerof C-6, C-8, C-10 repeating monomer units. In addi-tion the purified inclusion contains four major proteinsthat have been purified and identified as the poly-merase and depolymase enzymes and two structuralproteins. Using the immunogold antibody label ofthese proteins and electron microscopic examination,we could construct a macromolecular model of thePHA inclusion that is shown in Figure 8 (Fuller 1995,1999).

The organization of this prokaryote inclusion re-sembles that of the chlorosome in the green pho-tosynthetic bacteria. Both are partitioned from thecytoplasm by a lipoprotein monolayer boundary, andboth are organized as independent structures in thecell. Neither the PHA prokaryote inclusion nor thechlorosome in the green bacteria is structured as a clas-sical membrane lipoprotein bilayer, which separatestwo water-containing compartments as in eukaryotes.Rather, both separate a water-based cytoplasm from alipid-containing area. Although cost may prevent thesebiomaterials from being commonly used for awhile,we have made great strides in our knowledge of the

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Figure 9. Down in the dumps? Not a bit of it. Clint Fuller and Bob Lenz, Professors Emeriti, in their most recent laboratory. Photograph fromthe University of Massachusetts, Amherst.

prokaryotic structure and function, as well as in awhole new era of material science in the last 10 years.

Bob Lenz and I now are retired Professors Emer-iti who both stay active in the field. Our laboratoriesare closing down as the dollars rightfully flow to ouryounger colleagues, many of whom we have trained.As shown in Figure 9, we occasionally visit our fieldstation in Amherst so that we remind ourselves of thehorrible world of non- degradable plastic waste in the20th century and dream of a future in biodegradableplastics in the 21st century.

This wonderful 50-year journey in science rangesfrom Protozoan nutrition via biochemical genetics andphotosynthetic carbon metabolism, cell structure andfunction in photosynthetic prokaryotes to microbialbiomaterials. This research has produced 225 publica-tions and many honors. Of the latter, I most treasuredthe Chancellor’s Medal from the University of Mas-sachusetts in 1988, given to a faculty member fordistinguished research and scholarship, for my workon photosynthesis. The award included an invitation

to give a university-wide lecture; mine I entitled ‘Lightand Life’. It’s nice to be so honored at home! In 1997I received an honorary ScD, from Moscow State Uni-versity in Russia. Very honored, I dedicated my awardlecture to the late Professor Elena Kondratieva (Olsonet al. 1996), a distinguished microbiologist who wasmy friend and colleague. She had trained many youngstudents and had collaborated with many of us in workon microbial photosynthesis.

Ending this perspective, I would like to reflect alittle more on the people who have traveled this roadwith me. I have cited many of my mentors, associatesand students. My aging memory alone is responsiblefor any persons who may have been omitted inad-vertently. Special recognition goes to those scientificcolleagues who have been with me from the begin-nings in the 1950s and are still be with me today. Mythanks for being there at the right time go to AndyBenson, Martin Gibbs, Howard Gest, Sam Conti, Ger-hard Drews, Herbert Zuber and, of course, Bob Lenz,my current colleague and partner. Serendipity and suc-

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cess couldn’t have happened if you all hadn’t beenthere at the right moment. Clearly I owe a debt ofgratitude to two administrators, along the path of thiscareer: namley Marsh Tenney at Dartmouth, who hireda young and rather inexperienced person to help re-build a school where I learned a lot and hope thatI added some; and Oswald Tippo, Chancellor at theUniversity of Massachusetts, who hired me in 1971and was a valued colleague and friend until his death at87 in the summer of 1999. He is pictured in 1948 withOtto Warburg at the University of Illinois in Figure 5of this paper.

On a personal level, I am forever grateful to mywife and life-long partner Carol, who along with mynow grown children, David, Kathy, Lynn and Jon, alljoined my peripatetic career from 1946–1971. Livingin California, Long Island, England and Europe wasterrific. Being at Dartmouth, Oak Ridge and the Uni-versity of Massachusetts, Amherst, where my careerbegan and will end, were joyous times. My family hadwonderful travels, camping trips, and expeditions tomuseums and concerts. Now my four children with ournine grandchildren are off on their own journeys.

Acknowledgements

I owe a great deal of gratitude to the governmentalagencies and private industries that supported our re-search over the years. These institutions include: TheNational Institutes of Health; the National ScienceFoundation (from 1961–1998); The Atomic EnergyCommission (Dept. of Energy); The Office of NavalResearch; E.I. Dupont; Proctor and Gamble; John-son and Johnson (Focused Giving Award); Rhome andHas and the University of Massachusetts. I want tothank the reviewers for their helpful and constructivesuggestions that improved this manuscript greatly.

This manuscript was edited by Govindjee. He notonly patiently, and somtimes painfully I am sure, in-troduced me to electronic correcting and editing, butmade the manuscript both literate and readable.

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