Relics, replicas and commemorations

Download Relics, replicas and commemorations

Post on 15-Sep-2016

220 views

Category:

Documents

2 download

Embed Size (px)

TRANSCRIPT

<ul><li><p>Relics, replicas and commemorationsSoraya de Chadarevian</p><p>Department of History and Philosophy of Science, University of Cambridge, Free School Lane, Cambridge, CB2 3RH, UK</p><p>Several replicas of Watson and Cricks demonstrationmodel of DNA built at the Cavendish Laboratory inCambridge in 1953 exist, but where is the original?Once the object of intense discussion but soon super-seded by more refined models built at Kings CollegeLondon, it slowly fell to pieces and was eventually dis-assembled. Twenty years after it was first constructed,some of its pieces resurfaced at Bristol. By that time,the value attached to the original incarnation of thedouble helix had changed substantially, and the ScienceMuseum in London commissioned a replica of themodel, with some of the original parts built into it. Themodel was hailed as the nearest there is to the original.It has since served as prototype for further replicas.Meanwhile the spidery model of DNA has become theultimate icon of 20th-century life sciences, and morepieces supposedly belonging to the original continueto appear at auction.</p><p>In 1971, Arthur Arnone, one of many young Americanresearchers spending a three-year postdoctoral stint at the</p><p>world-famous Medical Research Council (MRC) Laboratoryof Molecular Biology (LMB) in Cambridge, detected a fewmetal plates among other jigs on a dusty bench in themodel-building room [1]. Arnone picked up what herecognized as an adenine base, one of the four basespresent in nucleic acids. In that moment, Francis Crickwalked by the door. Cheerfully he confirmed that hethought it was one of the bases he and James Watson hadused to build their DNA model in 1953, almost 20 yearsearlier when the laboratory was still housed in thephysics department. Arnone got him to sign the basewith an ink marker. When Watson visited thelaboratory a year later, he managed to make him addhis signature on the back.</p><p>Arnone has remained the fond custodian of the originalbase for over 30 years. Once a year, when he gave hislectures on DNA structure at the University of Iowa, hewould bring the base along for the students to see, but nottouch. Invariably he earned their spontaneous applause.He has now returned the base to the Cambridge laboratoryfor the 50th anniversary of the double helix (Fig. 1).</p><p>Fig. 1. Base plate (with central hole) collected by Arthur Arnone in Cambridge in 1971 and signed by Francis Crick and (on the other side) by James Watson. The function of</p><p>the red color mark is unknown. The plate is currently on display in the exhibition Representations of the Double Helix at the Whipple Museum of the History of Science in</p><p>Cambridge. Photograph by Leslie McKeany. Courtesy of the Medical Research Council Laboratory of Molecular Biology, Cambridge.</p><p>Corresponding author: Soraya de Chadarevian (sd10016@cam.ac.uk).</p><p>Review Endeavour Vol.27 No.2 June 2003 75</p><p>http://ende.trends.com 0160-9327/03/$ - see front matter q 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0160-9327(03)00060-7</p></li><li><p>If, in this anniversary year, we want to pay a visit to thecelebrated structure, a good bet is the Science Museum inLondon, which boasts not one, but two DNA models withmetal plates and spidery backbone that are, on first sight,almost indistinguishable from each other. Yet anothermodel has recently been built in the workshop of the LMBin Cambridge for display in the Whipple Museum of theHistory of Science. However, Watson and Cricks originalmodel no longer exists, and Arnones base plate is only oneof a confusing number of such plates held in private handor by museums.</p><p>Despite the importance attributed to the model in theaccounts of Watson and Cricks discovery of the DNAdouble helix, little is known about its actual fate. This is allthe more surprising given the value attached to physicalartefacts of the event. Tracing the busy career of Watsonand Cricks model provides unique insights into themaking of a 20th-century icon.</p><p>A model six-feet tallWhat then happened to the model Watson and Crick builtin 1953? First, we need to clarify which model we speak of.Model building was Watson and Cricks main approach intheir attempt to interpret available data, much of itproduced by Rosalind Franklin and her research studentRaymond Gosling at Kings College London, and thus todeduce the three-dimensional structure of DNA. Caltechscientist Linus Paulings success in determining thestructure of the polypeptide chain in proteins throughmodel building had convinced the two researchers of thepower of the method. Watson and Crick built many modelsthat were quickly dismantled because the suggestedstructures did not lead to any satisfactory solution. Fortheir various attempts they used the brass skeletal modelbuilding parts that were in the Cambridge laboratory forprotein modeling. Whilst playing with cardboard models ofthe bases, drawn according to Jerry Donohues suggestionof the prevalent forms in which the bases occurred in thecell, Watson fell upon the mechanism of base pairing theactual novel feature of their structure. The schematic 2D(rather than 3D) representation of the bases certainlyfacilitated Watsons work, just as the paper model of thepolypeptide chain had helped Pauling, although this is apoint often lost in anecdotal details. Watson had orderedmetal cut-outs of the bases from the Cavendish workshop[2]. These took several days to produce. Getting impatient,he and Crick started building models with the usualskeletal building parts for the backbone and just aconstraint for the bases, at this point confidently placedat the inside of the two helical chains. Probably severalsuch models were built, although no photographic or otherrecord of these working structures survives [3]. Thismeans that the model we know from the famous picture,taken in May 1953 by Cambridge freelance photographerAntony Barrington Brown, was not Watson and Cricksactual working model but a later model, built fordemonstration [4]. Indeed, when a photograph of themodel first appeared in print in Watsons best-selling TheDouble Helix, the caption read: the original demonstrationmodel of the double helix [5] (Fig. 2).</p><p>This photograph, probably taken at a Cavendish open</p><p>day in July 1953, and Barrington Browns photograph originally taken to accompany a report on Watson andCricks discovery in Time magazine (but not published atthe time) are, to my knowledge, the only extant picturesof the model. None of them appeared in the scientificpublications on the structure. Rather, Watson and Cricksfirst publication in Nature, drafted before the demon-stration model was completed, included only a diagram-matic sketch of the structure, drawn by Cricks wife Odile,whilst a later paper giving a fuller description of thestructure featured photographs of a rough scale modelbuilt in the Cavendish workshop for use in the lectureroom [68]. Nevertheless, the two casual photographsplayed a pivotal role in the subsequent history of themodel.</p><p>There was no press conference following Watson andCricks conclusion of their work on the structure. This wasnot part of British academic culture at the time [9]. Inaddition, the proposed structure was not more than ahypothetical model and still awaited to be tested againstmore accurate experimental data. The six-feet tall modelstanding in Watson and Cricks office in the Cavendishnonetheless served to convince fellow scientists andimpress foundation officers. Visitors came to see themodel in the flesh.</p><p>Fig. 2. The original demonstration model of the double helix (probably July</p><p>1953). Photographer unknown. Courtesy of the James D. Watson Collection, Cold</p><p>Spring Harbor Laboratory Archives.</p><p>Review Endeavour Vol.27 No.2 June 200376</p><p>http://ende.trends.com</p></li><li><p>Yet the fragile construction was not built to last. In oneof Barrington Browns discarded photographs, we seeCrick repairing the structure when it was not more than afew weeks old. Soon, it also emerged that the structure wasnot correct in all detail. Pauling for one showed that thetwo bases guanine and cytosine were held together bythree rather than by two hydrogen bridges as had beensuggested by Watson and Crick. The bases were alsomoved too far from the central axis of the structure. Moreprecise measurements of various parameters soon led tothe construction of more accurate models at Kings CollegeLondon [10]. Watson and Cricks model neverthelesssurvived in the Cavendish until the early 1960s, whenthe group moved to the newly built LMB on the outskirts ofCambridge. In the autumn of 1962, the same year as themove, Watson and Crick, together with Maurice Wilkins,were awarded the Nobel Prize for their work on thestructure of DNA.</p><p>In the new laboratory, the model found a place in thecommunal model room, but soon became neglected. Moreand more pieces broke away. Nobody seemed to bothermuch. Eventually, the dilapidated model was dismantledand as was usual practice, its parts were mixed up withother modeling material to be used for new model buildingprojects.</p><p>From Bristol to LondonArnone may well have been the first to turn a remnantfrom Watson and Cricks model into a relic, a historicalitem worth collecting. The autographed piece also servedas a memento or souvenir of his time at the prestigiousLMB, where he crossed paths with Crick, Watson andothers who had become leading figures in the field.</p><p>Nonetheless, Arnone was lucky to come across someforgotten plates in a dusty corner of the model room.Shortly before he came to the laboratory, several metalplates had been packed up apparently inadvertently so with other model-building material for protein crystal-lographer Herman Watson when he moved fromCambridge to take up a position in Bristol. It wascustomary for scientists to take their model materialwith them when moving. Packing was done by techniciansin the laboratory. As a token, the parting scientist left acontribution to the tea fund.</p><p>In the mid-1970s, Ann Newmark, research assistant ofthe chemical collection at the Science Museum in London,travelled to Bristol to discuss with Herman Watson thereconstruction of the forest of rods model of myoglobin, animpressive structure, pieces of which she had discovered inthe museum store. It had been the first ever atomic modelof a protein, built by John Kendrew at the LMB. HermanWatson had been involved in the later stages of the workand was the nearest at hand to help. At Bristol, Newmarkdiscovered the flat metal plates, some of which werereconstructed in a makeshift DNA model for the students.Watson agreed to let the Science Museum have the originalpieces if replacement plates were provided. Newmark gotthe Science Museum workshops to cut some metal platesand duly received the set of original plates from Bristol,except for a single plate that remained incorporated in theBristol model [11]. It appears that the set acquired by the</p><p>Museum consisted of eight base pairs (i.e. sixteen bases)[12].</p><p>Farooq Hussain, a research student at Kings CollegeLondon, was engaged in reconstructing the three-strandedmodel of DNA that Pauling had proposed shortly beforeWatson and Crick published their double-stranded one.Hussains aim was to photograph the model for inclusion ina biography of Pauling he was writing. He was equallykeen to try his hand at the Watson and Crick model andhappily agreed to build a facsimile for the Science Museumusing the plates acquired from Bristol. Crick offered tohelp as much as he could, although according to Hussainhis memory seems to be a bit vague as to exactly what themodel looked like [13]. A photograph of the original model probably one or the other of those mentioned above offered useful guidance.</p><p>The replica was completed in time for the opening of therefurbished chemistry gallery in March 1977 (Fig. 3), andhas been on show in the Science Museum ever since. In themid-1980s, it became part of the Living Moleculesexhibition celebrating 40 years of molecular biologyresearch in Britain. From there, it was moved to theHealth Matters gallery in the museum, and more recentlyto the Making the Modern World gallery. In its newlocation, the model is dwarfed by a Lockhead Airlinerhanging over it and other big artefacts of the erasurrounding it, among them a V2 rocket, a Rolls-RoyceMerlin Engine, and a vertical tower of 1950s automobiles.</p><p>Fig. 3. Replica of Watson and Cricks 1953 model of DNA with some original base</p><p>plates built by Farooq Hussain from Kings College London in 1977. The model is</p><p>on display in the Making the Modern World gallery at the Science Museum,</p><p>London. Source: Science Museum/Science &amp; Society Picture Library. Slide no.</p><p>SCM/BIO/C1000271.</p><p>Review Endeavour Vol.27 No.2 June 2003 77</p><p>http://ende.trends.com</p></li><li><p>The original label faithfully stated: the nearest there is tothe original model. More recently this caution has beenbrushed aside and the model is now simply presented asCrick and Watsons DNA model 1953. Only when readingthe small print will the visitor understand that this is areplica with some original base plates. The model hasserved as prototype for further replicas produced in themuseum. The first one of these, adjusted in height to whatretrospectively seemed the more correct size, is also ondisplay. A more recent one was built to order and sold toJapan. The first replica has meanwhile undergonerestoration, sealing its status as a museum object.</p><p>Memories and re-enactmentsWhat had triggered the transition of the base plates theonly distinguishable parts of Watson and Cricks modelbecause they had been purpose-built from neglectedlaboratory items to collectibles some 20 years after theiroriginal use? And what, besides the chance discovery of thebase plates in Bristol, motivated the Science Museum toinvest resources in rebuilding Watson and Cricks 1953model? On one level of course, it is often only time thatchanges the value of objects. Only once their use is notobvious anymore or their existence threatened, do thingsseem worth preserving. However, in the case of the doublehelix, more was at stake.</p><p>From the late 1960s, scientists started to celebrateWatson and Cricks determination of the double-helicalstructure of DNA as the origin of a new science of lifebased on a molecular understanding of genes and theirfunctions. This origin account of the new science was hotlycontested, but the development of recombinant DNAtechnologies in the mid-1970s heightened the interest inDNA and gave the origin account new leverage. Even moreimportant for the public perception was Watsons book TheDouble Helix, which came onto the market in 1968 [14].This brash account of the race to discover the structure ofthe genetic material was as much criticized as it becamesuccessful. The book did not only establish the dramaticstory of the discovery, but also introduced the talldemonstration model of DNA as a central figure alongsideWatson and Crick, the other two heroes of the story. Thetwo photographs of the model, published here for the firsttime, underlined this fact. Confirming its hero status, the21st birthday o...</p></li></ul>