Unravelling the Double Helix

by Gareth Williams

  At the end of February 1869, Miescher wrote an excited letter to his parents. Forget those proteins; he had discovered the first compound in the cell nucleus and it did ‘not belong to any type of protein’. On 21 August, he sent them an update: ‘nuclein’ was completely novel and might be an acid. He speculated that it was important in normal cells, and perhaps in cancer. Hindsight makes his words look uncannily prophetic, but this was just the flight of fancy of a novice research student.

  Miescher’s apprenticeship in Hoppe-Seyler’s lab had gone well, but it was already time to move on for an ambitious young man who wanted to keep up the family tradition of being a professor at the University of Basel. His next destination was Carl Ludwig’s celebrated laboratory in Leipzig, to study the nerve pathways that carry pain impulses to the brain. Miescher rounded off his spell in Tübingen by writing up his findings. On 23 December 1869, the day before leaving for Leipzig, he wrote to tell his parents that he was sending his paper on nuclein to the world’s best journal for ‘medicinal chemical investigation’. He thought that it should be accepted but wisely added, ‘as long as Hoppe-Seyler does not refuse it’. This was because the journal in question was edited by its founder, whose name graced its cover: ‘Hoppe-Seylers Medizin-Chemische Untersuchungen’.

  Publish or perish

  Neurology in Leipzig made a stark contrast with the kitchen chemistry of Tübingen: a cosmopolitan free-for-all, with students and visitors jostling to watch Carl Ludwig’s masterly dissections of the central nervous system. ‘Italians, Frenchmen, Swedes, Norwegians, Russians, Americans, Muhammadans were crowded around the experimentation tables,’ wrote Miescher. However, he soon had other distractions. Basel University advertised a lectureship, the first rung on the ladder leading to the hoped-for Chair – and thanks to Felix Hoppe-Seyler, Miescher stood little chance of being appointed.

  Hoppe-Seyler took months to let Miescher know that he was rejecting the paper on nuclein; it was too exciting to be believable, and had to be verified by someone more experienced. Miescher must have been devastated, but replied by return to say he was prepared to wait. That took another year, during which Hoppe-Seyler ignored Miescher’s increasingly desperate letters. The lectureship in Basel depended on this paper, Miescher pleaded, and someone else might stumble across nuclein in the meantime. Finally, in early 1871, Hoppe-Seyler wrote to tell Miescher that his paper would soon appear in the Untersuchungen. He had repeated all of Miescher’s experiments to satisfy himself that his apprentice had not made a dreadful mistake and had assigned Miescher’s successor, a Hungarian student called Pal Plósz, to look for nuclein in the blood cells of birds and snakes.

  The three papers by F. Miescher, F. Hoppe-Seyler and P. Plósz were published together in the Untersuchungen in spring 1871, almost eighteen months after Miescher had sent in his manuscript. Plósz’s paper read as though he, not Miescher, had invented the extraction method, but Miescher’s claim to the discovery was rock-solid. Hoppe-Seyler himself had ‘fully confirmed’ Miescher’s ‘unexpected’ finding which was ‘of great importance’, because it laid bare for the first time ‘the chemical composition of the nucleus’.

  This ringing endorsement from the most powerful man in physiological chemistry was perfectly timed. Shortly after, the discoverer of nuclein was appointed Lecturer in Physiology at the University of Basel.

  The hungry testes and other mysteries

  Miescher’s welcome-home package was not that generous – makeshift laboratory space in a corridor and 0.25 of a technician – but his rapid ascent of the slippery pole of academia proved that it can be difficult to keep a good man down. In the summer of 1872, Wilhelm His was poached for the Chair of Anatomy in Leipzig, creating an ideal opportunity to keep things in the family. On 1 November 1872, at the indecently young age of twenty-eight, Friedrich Miescher was appointed Professor of Physiology at Basel.

  This allowed him to concentrate again on nuclein, and in material that was nicer than pus. Basel is bisected by the mighty Rhine, one of Europe’s great salmon rivers. Every autumn, its waters are full of fish on a mission, returning to their birthplace to ensure the survival of the species. During their 800-kilometre pilgrimage from the North Sea, the salmon are resculpted to make them fit for the sole purpose of reproduction. Muscles not used for swimming wither away, while the ovaries or testes expand massively and fill up with eggs or sperm. A male salmon as far upstream as Basel is a gift from nature for someone wanting industrial quantities of nuclei. Its testes are six times their normal size and stuffed full of spermatozoa – each of which is a nuclear warhead stuck on a propulsion unit made of proteins that helpfully fall apart in weak acid.

  Miescher’s working day now began before dawn, when he and his technician would meet on the bank of the Rhine, nets in hand. The basic recipe was simple: take a bucketful of fresh salmon testes; press through cheesecloth; wash with water; add acetic acid; then leave to stand until the fine grey dust of decapitated sperm heads settles out. Thanks to the salmon, Miescher’s research quickly pushed ahead. He confirmed that nuclein was acidic and showed that it could not diffuse out of a parchment bag, which meant that it was a large molecule. When he had enough to analyse in detail, he had a stab at working out its chemical formula: he estimated this to be C29H49N9O22P3, giving a molecular weight of 968.*

  As well as nuclein, Miescher found novel proteins in salmon sperm heads. One was rich in amine groups which made it basic (alkaline), and it could be coaxed into forming ‘beautiful prismatic crystals’ by adding a platinum salt. He christened this nuclear protein ‘protamine’, and suggested that it was tightly associated with the acidic nuclein.

  At first, Miescher’s research proceeded swimmingly. It spawned a major lecture that impressed the prestigious Basel National History Society (1873), followed by papers on protamine and nuclein in sperm from frogs, carp and chickens (1874). But at that point, Miescher’s glittering career, which had ignited in such a blaze of energy and success, began to fizzle out.

  Various misfortunes caught up with the young professor, some of which were of his own making. Miescher was a workaholic who believed that sleep was a waste of time, and unlike his father and uncle, he was forever being tripped up by the baggage that comes with a professorship. He made especially heavy weather of teaching; a few bright students found him inspirational, but the consensus was uncharitable: ‘hard of hearing, myopic, in his own world’. Later, he wrote to a friend: ‘If I could instil into my students the idea that physiology is interesting and easily acquired, I would have great success as a teacher.’ Unfortunately, he made it boring and difficult.

  The world into which he retreated – research – also turned hostile. His downward slide began when he investigated the wasting – he called it ‘liquidation’ – of salmon returning to the Rhine to breed. Miescher showed that the muscles not needed for the swim home are emptied of protein, which is shunted into the testes or ovaries to fuel the growth of sperm or eggs. These studies demanded meticulous dissections of thousands of fish and took years, but produced just one paper. Even worse, this work caught the eye of bureaucrats who asked him to study the nutritional status of Basel’s least migratory citizens – the inmates of the city’s prison. Miescher produced such an excellent report that he was quickly swamped by requests for nutritional surveys from across Switzerland. He realised too late that he had to say no in order to survive.

  By then, the thread of continuity with the laboratory bench had frayed, and the passion that used to drag him into a freezing river before dawn had all but died. Miescher fell into a vicious circle of working even harder and even less productively, and the pile of half-finished experiments and papers started to grow. A portrait at this time shows a balding, tense man who was clearly preoccupied by bigger things than having his photograph taken (Figure 2.1).

  Magic Mountain

  The last third of Miescher’s life was marked by three milestones. The most conspicuous, in 1883, was the grand opening of his pet project, th
e university’s new Anatomy-Physiology Institute. Miescher christened this the ‘Vesalianum’ to honour the sixteenth-century Basel anatomist, Andreas Vesalius, whose De Humani Corporis Fabrica laid the foundations for the scientific study of the human body.

  Another milestone had already been planted, but was buried in the tangled undergrowth of Miescher’s working life. On the morning of 21 March 1878, his lab routine was interrupted when a group of friends turned up and took him away. Their destination was a church in the city centre, where those waiting included a quiet dark-haired girl called Maria-Anne Riisch. Friedrich had proposed to her three months earlier. Now that the groom had turned up, their wedding continued more or less on schedule, and three children duly followed. The Miescher family eventually moved to an imposing house near the Cathedral Square, which backed conveniently on to the Rhine and its mission-focused, emaciated salmon.

  The third milestone, in 1890, was the onset of a dry cough. The diagnosis – tuberculosis – was devastating. Tuberculosis killed more people than plague or cholera and there was no effective treatment; the only hope was in the statistic that ‘mountainous countries such as Switzerland have a very low death-rate from tuberculosis’. Davos, on the German-Swiss border (‘where the air is like champagne’), had become a world-famous centre for the Luftliegekur method, in which tuberculosis patients lay outside in the open.

  Figure 2.1 Friedrich Miescher.

  In 1890, Miescher began visiting a sanatorium in Davos for several weeks at a stretch; four years later, he abandoned the mists of Basel and moved in permanently. The man who had been too busy to get married finally realised what time was all about. He was not one of those heroic souls who make the most of the life left to them while staring their own mortality in the face. The ‘passion of the hunter and soldier’, which had driven him so hard as a young scientist, now deserted him. Paralysed by his own lethal cocktail of indecision and perfectionism, he made no headway on his unfinished work.

  This was a grim time for Miescher. His wife stayed in the family home in Basel, although precious little of the family now remained. Their first two children had died young, and the surviving daughter was locked away in an asylum. In June 1895, Miescher reached a psychological point of no return and wrote to the university to resign from his beloved Chair of Physiology; in response, the university increased his pension and the City of Basel sent a note of thanks for all that he had done.

  Shortly after, he received a letter from Carl Ludwig, his former mentor at the Neurological Institute in Leipzig, which would have brought some solace: ‘Sad as it is, there remains for you the satisfaction of having completed immortal studies on the nucleus . . . As men work on the cell in centuries to come, your name will be gratefully remembered as the pioneer in this field.’

  Compare with the following: ‘Friedrich Miescher was a well-known and able scholar . . . If he did not reach the highest peaks of achievement, this was due solely to certain weakening and obstructing factors in his organisation.’ This was the best that the University of Basel could offer just a few weeks later, at the memorial service for their late Professor of Physiology.

  Leftovers

  Friedrich Miescher was three weeks past his fifty-first birthday when tuberculosis carried him off on 26 August 1895. This was two weeks after more bad news reached him from Lake Constance, just 80 kilometres to the north of Davos. A friend and colleague had died suddenly at his summer residence while measuring the gases dissolved in lake water. Everyone was shaken, because the seventy-year-old Felix Hoppe-Seyler still had ‘a youthful and elastic step’ and ‘appeared to have many years of life ahead of him’.

  Miescher’s passing left few ripples on the smooth surface of Basel society, let alone the wider world of science. The university felt that their ‘able scholar’ was adequately commemorated in his splendid Vesalianum. His personal legacy was not that great: a poor teacher, and only nine papers from three decades of research (less than one-tenth of Hoppe-Seyler’s output). There was no point in speculating about ‘what if’, because those ‘weakening and obstructing factors’ – workaholism, pathological perfectionism and the inability to finish things off – were hard-wired into his constitution.

  Miescher left it to others to salvage his reputation. The main responsibility was shouldered by Wilhelm His, as a labour of love for his favourite nephew. He and friends worked through the heaps of Miescher’s laboratory notes, unfinished manuscripts and letters, polishing rough-cut gems and filling in gaps to show how he would have advanced knowledge – if only he had done what every scientist is expected to do, and published his research. It took them well over a year. The Histochemical and Physiological Works of Friedrich Miescher came out in two volumes in 1897, two years after his death. A subtitle explains that the works were ‘gathered and edited by his friends’. The book reads like a Festschrift to celebrate a successful career; it is also the story of a fascinating life, told more eloquently than Miescher himself could ever have done. The frontispiece is the brooding portrait of the old Miescher, apparently contemplating failure rather than success.

  There are some painful revelations in the eighty-plus letters which Miescher wrote to fellow scientists, family and friends: the birth, maturation and death of ideas; the emotional switchback of a life in research; his excitement at discovering nuclein; and the crushing disappointment when Hoppe-Seyler rejected his first paper. Miescher gives glimpses of the inner conflicts which made him what he was, and which prevented him from becoming what he could have been. ‘As long as I have not paid my old debts, I cannot go on to new tasks . . . If I had as much time as material, I would advance very quickly.’ Unfortunately, time was never on his side, whether as the professor in Basel struggling with his teaching, or the invalid in Davos whose lungs were being chewed away by tuberculosis.

  There is a poignant flash of insight in one of his last letters: ‘Only when I come across a half-formed fragment of something I discovered, published by someone else, do I realise what could have been achieved.’ One of his students gave a terser assessment of all that Miescher failed to do: ‘A ship loaded with precious treasures, which sinks just as it enters port.’

  Full circle

  During his last months in Davos, with the pile of unfinished manuscripts untouched at his side, Miescher continued to theorise about the chemistry of life – but only in letters that he expected would remain unpublished.

  He was fascinated by how characteristics are passed down from one generation to the next, and especially the identity of the ‘large, complex’ molecules in which the instructions for life must be written. Some of his thinking seems strikingly modern – notably his belief that these instructions could be conveyed by a small repertoire of characters, ‘just as all the words and concepts of all the languages can be expressed in between 24 and 30 letters of the alphabet’.

  This looks like a premonition of the genetic code which was postulated during the 1950s and cracked in the late 1960s. However, nuclein had nothing to do with it. Writing to Wilhelm His in late 1893, Miescher argued that only proteins were sufficiently large and variable to transmit heredity. He calculated that subtle tweaks in the structure of a large protein could produce over a billion different variants – easily enough to carry millions of detailed instructions. Nuclein was too small and too simple to do the job. Its molecular weight of under 1,000 was dwarfed by big proteins, which exceeded 10,000. Although its structure was still unknown, it could never compete with the diversity of proteins.

  Then what did nuclein do? Miescher thought that it might store phosphorus, a key element in the cell, or act as a kind of scaffold that supported the essential components – proteins – inside the nucleus. He refused to be excited by his brainchild even when it was claimed, a couple of years before he died, that nuclein was identical to ‘chromatin’, recently identified as the material from which chromosomes were made. And when August Weismann, the celebrated German geneticist, suggested that nuclein could be the substance of heredit
y, Miescher dismissed Weismann’s ‘speculations’ as ‘unclear and outmoded’.

  By the time that Miescher made his last trip from Davos to Basel, he had done his best to bury nuclein, the molecule that could have made him famous in his own lifetime. And he had established the tradition of assuming that only proteins could be the stuff of genes – a prejudice that persisted right up to the discovery of the double helix.

  Too little, too late

  Shortly before Miescher died, reports of a dramatic new drug surfaced in America. US Patent Application No. 587, 278, filed by John Carnrick of New York on 4 January 1895, was a unique tissue preparation which stimulated the nucleus, overpowered ‘toxic germs’ and was set to revolutionise medicine. In a dazzling presentation given on 7 May 1895 to the American Medical Association in Baltimore, Dr T.O. Summers of St Louis described how this new drug induced ‘molecular vibration’ in the nucleus. Unlike the ‘useless rubbish’ which doctors usually dished out, it had ‘a most wonderful power’ in life-threatening illnesses, including cancers, blood-poisoning – and tuberculosis.

  Summers’s talk was printed in the Journal of the American Medical Association a few weeks later. Miescher would have been intrigued to read about the new wonder drug which, if Summers was right, could have saved his life. Sadly, he died before the journal reached Switzerland.

  What was it? Prepared from the thymus and other tissues of calves, the wonder drug had a high phosphorus content and was called ‘Protonuclein’, because it incorporated the best possible sources of that miraculous molecule, nuclein. And scepticism was suspended while doctors waited to see whether Protonuclein really was a remarkable gift from the frontiers of research – or just another quack medicine from a charlatan trying to make a quick buck.