Taxonomic Technology: Electrophoresis & Classification in Agricultural Botany (Part 1)

My second ever work-in-progress seminar at the University of Leeds introduced attendees to the second chapter of my PhD, which examines the use of laboratory machinery and biochemical methods to identify and analyse crop varieties at the National Institute of Agricultural Botany (NIAB) during the 1980s. By the late-twentieth century, classifying agricultural plants was a difficult task. More and more varieties were submitted to NIAB by plant breeders, while the distinguishing characteristics of varieties grew smaller and smaller. Identifying and classifying varieties had traditionally relied upon botanically-trained observers. Yet visual scrutiny of plants’ morphological characteristics was problematic, requiring both considerable expertise and grown specimens.

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The problem of classifying of agricultural plants is demonstrated by these images of celery varieties. Each column here represents a distinct variety: the correct classification of these samples by eye would be a near-impossible task for the untrained observer. From G.W. Horgan, M. Talbot and J.C. Davey, ‘Plant variety colour assessment using a still video camera’, Plant Varieties and Seeds (1995) 8: 161-169.

An escape route was provided to NIAB via a form of protein fingerprinting developed in biochemistry: electrophoresis. For historians of biology, electrophoresis is best known for its use by Lewontin and Hubby to break an impasse in population genetics during the 1960s. Electrophoresis was trialed at NIAB during the same period, to little avail. Matters changed during the early years of the 1980s, when staff at NIAB’s Chemistry and Quality Assessment Branch were able to apply electrophoresis to cereal varieties. Electrophoresis works by running an electric current through a gel in which a sample sits. As different proteins carry different charges, they separate into distinct “bands” (see below).

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An early image of a completed electrophoresis sample. The darker protein “bands” can be seen once the gel is chemically dyed. From R.P Ellis, ‘The identification of wheat varieties by the electrophoresis of grain proteins’, Journal of the National Institute of Agricultural Botany (1971) 12: 223-235.

Electrophoresis provided a new means of classifying agricultural plants and was promoted in NIAB’s publications as an efficient and modern technique of variety identification. The experience of the Institute during the 1980s chimes with what historians of science have termed the “molecularisation movement” in the life sciences. This movement is usually associated with genetics and the role of DNA and nucleic acids. Yet historians have called for broader studies under the theme of molecularisation, not least because of the broad use of terms such as “molecular biology” by scientists themselves. Financial gain and prestige came from NIAB’s research into electrophoresis; the technique still appears in guidelines issued by international agricultural bodies today, despite the rise of DNA sequencing. Yet electrophoresis was not the only method of classification investigated by NIAB during the 1980s, as future posts will explore…

 

 

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Molecular Biology and Evolution at ISHPSSB 2015, Université du Québec à Montréal

The Blog is Back! Following a few hectic weeks of international travel, including the International Society for the History, Philosophy and Social Studies of Biology (ISHPSSB) 2015 conference in Montreal, normal service can resume. ISHPSSB was the first international conference I had ever attended. With hundreds of attendees, it was also the largest! Nominally I was there to present a paper on a facet of my PhD research – the history of a largely ignored form of biotechnology know as somatic hybridisation (http://leeds.academia.edu/MatthewHolmes). But with multiple panels and sessions, ISHPSSB’s speakers were delving into everything from Darwin to embryology, ecology to agriculture. One of the most intriguing (and popular) panels discussed aspects of molecular biology and the modern synthesis in biology. As always, a few textual snapshots are provided below:

But first, some Montreal landmarks…

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Vassiliki Betty: The modern evolutionary synthesis brought together botanists, geneticists and paleontologists under a single conceptual framework – one which combined evolutionary ideas and Mendelian genetics – during the mid-twentieth century. By the end of 1950s, advocates of the synthesis was arguing for evolution as the unifying theory of biology. Links between chemistry, physics and biology also grew as biologists jumped on the ‘DNA bandwagon’. Yet all was not well in the new world of biology, as rifts between the new molecular biologists and traditional organism-focused biologists occurred in American Ivy League institutions. One well-known example is found in E.O Wilson’s memoirs, which described his Harvard colleague James Watson (co-discover of the structure of DNA) as the ‘Caligula of biology’, who aggressively drove the molecularisation of biology and even blocked the appointment of ecologists to the department.

Yet other noted figures felt no such clash. Botanist George Ledyard Stebbins Jr. embraced the techniques of molecular biology by the mid-1950s, despite his training in taxonomy and museum work. Chair of Genetics at UC-Davis during the 1950s and ’60s, Stebbins encompassed developmental genetics (which challenged Mendelian genetics) and postulated new mutation processes, including the easier formation of inter-specific hybrids in plants. In a 1968 paper he stated that modern synthetic theory was based upon multiple disciplines and acknowledged there were different answers to how characteristics – for example the neck of a giraffe – developed, given by field naturalists, Darwinians, developmental genetics and molecular biologists. None were wrong. All were correct, but incomplete.

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ISHPSSB President Michel Morange speaks to a packed room at the molecular biology session.

Michel Morange: Jumping to the mid-1980s, molecular biologists had accepted evolutionary synthesis, as the Luria-Delbrück experiments chased Lamarckianism out of microbiology. Molecular biologists used Darwinism in their work, isolating mutations to demonstrate the creative power of variation and selection. François Jacob (1982) stated that embryonic development had been ignored. But various molecular biologists continued to have ideas about the molecular mechanisms of evolution. Research was not always straightforward. The T-complex model, proposed by Dorothea Bennett in 1975, was supposed to demonstrate how embryonic development of mice was disrupted. Unfortunately the T-complex turned out not to exist. Yet other models, including gene regulation and  heterochronic mutation were successfully integrated. It is now acknowledged that there are different forms of evolution and progress in evolution occurs independently of the environment. The molecular biologists were largely Darwinian but did not follow the evolutionary synthesis to the letter.