Author: Ibon Cancio, UPV/EHU Associated Professor in Cell Biology; researcher in the ‘Cell Biology & Environmental Toxicology’ (CBET) research group of the Plentzia Marine Station (PiE-UPV/EHU); Spanish scientific representative in the EMBRC Committee of Nodes

George and Milana Manton gave birth to two daughters: Sidnie Manton, zoologist (entomologist) and Irene Manton, botanist. Sidnie was the 8th woman to become a fellow of the Royal Society in 1948 and Irene was the 18th. This was a distinction that made the Manton sisters co-fellows of scientists of the grandeur of Newton, Darwin, Faraday or Einstein, to name a few.

Irene Manton (born 17 April 1904, died 13 May 1988) studied biology in Cambridge and Stockholm, obtaining a lecturer position at the University of Manchester. She received her PhD on Crucifera (in plain English, the cabbage family) in 1920. Her academic career was based at the University of Leeds, where she was Professor of Botany from 1946 (first woman professor and head of a Department at Leeds) until 1969. 

She focused her research first on ferns but after 1950 she turned her attention to algae, always algae. In ferns, she studied hybridisation, polyploidy and apomixes, analysing their morphological structure using the ultraviolet microscope. This was like a preparatory transit for her later plunge into electron microscopy and the investigation of the ultrastructure of cells (=algae). The electron microscope (EM) was introduced into biological research rapidly after the Second World War and quickly became the ‘Ferrari’ of the moment, the kind of instrument that allowed the analysis of subcellular structures and organelles. This revolution arrived in Manton’s life in 1950 when, together with more senior professors that supported her proposal, she received the funds to purchase a brand new Philips EM not yet on the market. In collaboration with Bryan Clarke, who would develop a leading technical approach to manipulate and prepare swimming cells for visualisation both under the light microscope and the EM, she published the first photographs of the spermatozoids of a macroalgae, Fucus serratus. Here she revealed one of its main characteristic features, the flagellum. 

Irene was now able to study the sperm cells that she could not analyse under the UV microscope, and six papers came out in two years demonstrating the cytoskeletal structure of the axoneme, the core structure of cilia and flagella. Manton and Clarke produced a diagrammatic reconstruction of the ‘9+2’ microtubular structure of the flagellum from their micrographs in 1952. This was the first time that a reconstruction of an intracellular structure had been attempted. Manton found herself in the vanguard of biological electron microscopy and apparently, when she showed her beautiful micrographs at international meetings, the audience would cheer and break into applause. She was also a brilliant speaker not devoid of a sense of humour.

Portrait photo of Irene Manton
Portrait of Irene Manton (source: Wikipedia Commons)

It was at that moment that she visited the Marine Biological Association (MBA, current-day EMBRC partner) at Plymouth. There, two female characters met and joined forces: Irene Manton and Mary Parke. One had the technical skills to study the hipertiny and the need of cells for her studies (she was looking for sperm cells of algae), the other one had the biological resources and the urge to characterise them. Instead of sperm, Mary Parke had microalgae that she had just began to isolate, cultivate and describe through light microscopy. Many of these algae were flagellates, unicellular organisms with flagella. Their description was difficult because of the lack of distinctive characteristics which could be observed by a light microscope. Besides, marine phytoplankton is formed by different taxonomic groups that were mostly unknown at the time, and the literature on the topic was in ‘disarray’. Descriptions were in French, German, Russian and Scandinavian languages. Manton’s linguistic skills and her contacts with major libraries helped in opening the golden arc of the algae. Such skills had the remarkable ‘company’ of an increase of two orders of magnitude in the resolution power of the EM!

The first flagellates the two women studied were described as golden-brown, presenting three long finger-like appendages. Two of them were flagella and the other one they called the haptonema (apparently a structure that allows attachment to the substrate). These algae also showed plate-like scales, coccoliths, revealing distinctive patterns, characteristic of each species, that cover the cell surface. Details of the morphology of these scales became the major features for taxonomic identification as Parke needed. Visualisation of such patterning only required shadowcast whole mounts, but other secrets of their ultrastructure required the development of new approaches in cell processing and ultrathin sectioning.

Cell biology, and the use of the EM for the visualisation of the cell fine structure, began in New York at the Rockefeller institute with Porter, Claude, de Duve and Palade. The Nobel prize in medicine awarded to Claude, de Duve and Palade would recognise those developments in 1974. In 1952, Fawcett (Harvard Medical School) and Porter published photographs from ultrathin sections of ciliated epithelia of different animals corroborating the 9+2 reconstruction published by Irene Manton. In 1954, she visited the Rockefeller Institute to learn how to produce such ultrathin sections, necessary to see the cell ultrastructure under transmission EM (TEM). She produced her first sections of the green alga Pandorina, obtaining photographs of the 9+2 flagella that were published in the proceedings of the London EM Congress of 1954. Manton got one of the ultramicrotomes developed at Rockefeller to initiate the analysis of the fine structure of unicellular algae in the UK. As a consequence, the ubiquity of the 9+2 structure allowing a flagellum to beat in any eukaryotic cell was generalised. Now, it is generally the first structure that biomedicine science students are trained to recognise in TEM images.

Ciliated epithelium
Ciliated epithelium in a marine mollusc through TEM. The photograph on the left shows sections through six cilia in the lumen of a gland surrounded by microvilli and the photograph on the right shows a higher magnification image and the 9 + 2 structure of the axonemal of a flagellum. Photographs from the image record of the Plentzia Marine Station (PiE-UPV/EHU).

In the process of working with ultrathin section analysis fixation, embedding, sectioning and counterstaining, the ABCs of sample processing for TEM were developed. Manton returned to the Rockefeller Institute various times, something she used to do taking advantage of the Christmas holidays. During one such visit in 1956, while viewing sections of Chrysochromulina chiton, she saw for the first time the fine structure of the haptonema. It is unique and consists of three membranes surrounding a group of seven microtubules.

Another major breakthrough came from the EM analysis of the Golgi apparatus of most haptophytes, algae whose surface is covered by coccoliths. Were these massive plates of calcium carbonate produced internally? The Golgi apparatus was suspected to be the main secretory compartment of the eukaryotic cell but no proof had been obtained yet. In a series of papers with wonderful micrographs of the Golgi apparatus Manton and Parke demonstrated in the 1960s that indeed the coccoliths were produced internally in the Golgi cisternae, and secreted to cover the cell membrane surface. That was the proof that was lacking. First evidence came from Micromonas squamata, a species that is now called Mantoniella squamata. The small plates that cover the flagella in the class Prasinophyceae were also proven to originate in the Golgi apparatus.

Plaque Irene Manton University of Leeds
A plaque marking the work of Irene Manton on the Botany House at the University of Leeds (source: Wikipedia Commons)

In 1969, Manton was forced to retire from her professorship at Leeds. She was 65 and room had to be made for younger staff. However, Manton was not the kind of person that retires from life, and life for her was research. She subsequently published the then- unpublished papers she had written with Parke in 1970 and 1971. This initiated a sampling pilgrimage to apply her technical expertise with the EM to the analysis of phytoplankton obtained in situ from the environment. She had been a frequent visitor to the marine laboratory at Menai Bridge in North Wales, part of the University of Bangor. Now she toured the planet. She visited the Danish Arctic Station in Disko Island (Greenland) and Cape Town in South Africa in 1972, different places on the east coast of Canada in 1973, Alaska in 1975, and the Galapagos island in 1977. Samples were analysed under the EM during short visits to colleagues at different universities in Britain. Furthermore, she incorporated X-ray microanalysis into the study of their elemental composition. Working as a ‘freelance’ researcher, Manton published 29 papers based on these experiences. She revealed that there are many commonalities everywhere with ubiquitous species irrespective of the environment and she understood that there were myriads of unknown new species.

Manton received many distinctions and awards, besides becoming fellow of the Royal Society, among them the Linnean Medal (she was the first female President of the Linnean Society of London, 1973 to 1976) and the Schleiden Medal of the Leopoldina (Academy of Sciences of Germany). She was elected a Foreign Honorary Member of the American Academy of Arts and Sciences and was awarded honorary membership of the Danish Academy of Sciences and Letters. She received honorary doctorates at the Universities of McGill (1959), Oslo (1961) and Durham (1966). That means full recognition, but we shall always remember her as the scientist that made microalgae reference model organisms in cell biology.

Gold palladium image
Gold-palladium shadowing of Imantonia rotunda (now Dicrateria rotunda) and her scales observed though electron microscopy. Photographs by Sergio Seoane, Basque Microalgae Culture Collection.

 

Sabrina Gaber
Communication Officer

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