Science for Health
02 April 2013
Michael Sargent was born in 1943. He was educated at the Royal Hospital School in Suffolk, a school for the children and grandchildren of seafarers. His father was in the Royal Marines and Michael was very proud of his school and its naval traditions, and of the Royal Navy in general. He would always remind his friends when it was Trafalgar Day. He took a degree at Nottingham University, choosing to study botany because microbial genetics was taught chiefly in botany departments at that time. He stayed on to complete his PhD at Nottingham then spent three years as a postdoc with J. Oliver Lampen, Director of the Waksman Institute of Microbiology at Rutgers University in New Jersey, working on penicillinase secretion in Bacillus sp. He joined NIMR in 1969, working in two distinct research areas at different stages of his career at the Institute.
Recruited by Howard Rogers to the Division of Microbiology, Michael studied mechanisms of cell growth and division in the gram-positive bacterium Bacillus subtilis. Rod-shaped bacilli grow mainly in length and it had been surmised that surface extension of the cell wall and membrane might be coupled to chromosome replication and segregation. Using synchronous cultures of B. subtilis, involving the selection of essentially new-born cells by a method he devised, Michael investigated bulk patterns of synthesis of membrane proteins during the cell cycle. Further studies were directed towards examining the growth kinetics of individual cells by means of thymine starvation or nutritional shifts to richer media. Michael’s results, published in Nature, showed evidence for a doubling in the number of surface growth zones at nuclear segregation and an absolute requirement for DNA synthesis. Using restriction endonucleases, Michael also showed that the bulk of the circular chromosome could be liberated from the membrane but a small fraction that contained DNA-associated membrane fragments could be sedimented at higher centrifugal speed. Later work involved the isolation of the chromosome terminus.
After Howard Rogers retired in 1984, the MRC closed the Division of Microbiology for strategic reasons. Michael moved away from bacteria and joined the Laboratory of Embryogenesis headed by Jonathan Cooke. Leaving one's initially chosen field of research to begin in another field in mid-career is one of the toughest professional challenges that can face an institute staff scientist, but Michael's response to the challenge was characteristically strong and positive. He assiduously read the embryology literature and was soon making very valuable contributions. Indeed his contrasting background knowledge, particularly on the biochemical side, was an asset.
In the very early 1990's Michael transferred to the newly formed division of Developmental Biology headed by Jim Smith. Working with Xenopus and chick cDNA libraries, Michael succeeded in cloning and characterising two vertebrate homologues of the Drosophila gene Snail - a gene that is required for mesoderm formation. Roberto Mayor, working in Michael's lab using Xenopus embryos, characterised the expression of the Slug gene in Xenopus, though it was difficult at that time to explore its function in that organism. Michael then worked in collaboration with Angela Nieto (from David Wilkinson's lab in the Division of Developmental Neurobiology) and Jonathan Cooke. They showed that it was possible to interfere functionally with each gene in turn in chick (bird) development, establishing respective roles in the origin of the neural crest and of left-right asymmetry. This work led to Michael's co-authorship of two highly-cited papers in Science. Michael was happy to allow Roberto and Angela to continue working with Slug in Xenopus and Chick, respectively, after they left NIMR. Slug became a very important gene, not only because it controls key steps in embryo development, but also because vertebrate Snail-like genes are currently strong candidates for involvement in the cell-behavioural changes associated with metastasis in cancer.
From 1999 until his retirement in 2007, Michael worked with Tim Mohun in the Division of Developmental Biology, studying heart development in vertebrate embryos. Though a new area for him, he joined this work with characteristic enthusiasm, contributing the breadth and diversity of his scientific knowledge. A focus of the Division's work at that time was an attempt to develop the use of genetic studies using species of the amphibian, Xenopus. One major challenge was how to deal with the logistics of maintaining many different lines of frogs for this work and the animal husbandry costs this would entail. Michael worked on a method to obviate these problems by using cryopreservation as a way to store lines without husbandry costs. He devised a reliable protocol for cryopreservation of sperm from both Xenopus laevis and its cousin, Xenopus tropicalis, a method that rapidly gained widespread use.
Michael was always interested in schools and outreach activities, with expert help from his wife Jean who is a science teacher. In the early 1990s he organised the first Schools Day at NIMR, inviting local schools to send groups of Year 12 students to the Institute for an afternoon to learn about research. He ran the Schools Programme at NIMR for many years - arranging every year the Schools Days, the Research Summer School and the School Essay Competition. For the past ten years he also organised an annual meeting at the Institute for the University of the Third Age.
Towards the end of his career at NIMR, Michael was awarded a Winston Churchill Travelling Fellowship to visit Ethiopia, India and Canada in order to study the effect in later life of nutritional and other physiological stress on the developing foetus.
Michael read widely and had a very broad interest in biomedicine, stretching from biomolecular sciences through to public health. His ideas about how the prospects for human life might improve, together with an examination of the ethical checkpoints to biomedical intervention, were discussed in his book Biomedicine and the Human Condition which was published in 2005. He wrote several essays for the Institute’s annual Mill Hill Essays, and latterly had become a prolific book reviewer.
As a colleague he was of characteristic, almost constant positive mood and attitude, and the - for a biological scientist - unusual breadth of his social concerns and his reading made for lively discussions other than the work-related. Since our respective retirements these discussions had continued and greatly developed, due to Michael's emerging interests in global biomedical problems and in outreach/ public engagement with biomedical science.
Michael was the most stimulating of colleagues. He always had some new information to impart and had a fund of stories to tell. There was never a dull moment when Michael was around and his laugh could often be heard reverberating along the corridor. He was one of the most fearless of scientists; nothing daunted him, either theoretical or experimental. For example, when restriction enzymes were first used for molecular cloning they were extremely expensive. Michael set about extracting and purifying his own and soon had a stock which, characteristically, he shared with others. His advice and opinion on a wide range of ideas and techniques were valued by many people.
Michael was unbelievably kind and helpful to me when I was postdoc at ICRF, next door to NIMR. Later, as a colleague at NIMR, I appreciated his enthusiasm, his great expertise in things molecular, and his general bonhomie. Michael was always a pleasure to be with, and he was unfailingly energetic, kind, cheerful, and positive. Everyone at NIMR will miss him enormously.
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