Mary Frances Lyon (1925–2014) was an English geneticist
Lyon is best known for her discovery of X-chromosome inactivation. Lyon proposed her hypothesis on the behaviour of X chromosomes in XX females in 1961, originally to explain her findings on the coat colour of mice carrying sex-linked colour genes.
Lyon also made significant contributions to understanding environmental mutagenesis.
- Born on May 15, 1925 in Norwich, England
- 1946 – BA, Cambridge University
- 1948 – ScD, Cambridge University
- 1950 – Doctorate
- 1962 – Head of the Genetics section of the Radiobiology unit
- 1973 – Fellow of the Royal Society, FRS
- US National Academy of Sciences Royal Medal (1984), the Wolf Prize for Medicine (1997) and the Pearl Meister Greengard Prize (2006)
- Died on Dec 25, 2014 in Drayton, England aged 89 years
Lyon hypothesis (1961)
Through her mutagenesis experiments on mottled mice and building on recent discoveries that only one X chromosome is required and that sex chromatin consists of highly a condensed X chromosome (Susumo Ohno), Lyon came to build her hypothesis: that only one X chromosome in a cell is active, due to random inactivation of one of the two X chromosomes, early in embryological development and that the inactivation is permanent and mitotically stable. The inactivated X chromosome is condensed down and seen as sex chromatin (Barr body).
It is here suggested that this mosaic phenotype is due to the inactivation of one or other X-chromosome early in embryonic development. If this is true, pigment cells descended from cells in which the chromosome carrying the mutant gene was inactivated will give rise to a normal-coloured patch and those in which the chromosome carrying the normal gene was inactivated will give rise to a mutant-coloured patchLyon 1961
Lyonisation (Miller and Boscoe, 1963)
The inactivation of an X chromosome as first hypothesized by Mary Lyon. We now know X-inactivation involves a number of different mechanisms including DNA methylation, RNA-mediated gene silencing, and changes in chromatin modification/organization.
Mary Lyon medal of the UK Genetics Society (2014)
Established in 2015 to reward outstanding research in genetics to scientists who are in the middle of their research career
- Lyon MF. Gene action in the X-chromosome of the mouse (Mus musculus L.). Nature. 1961;190:372-373.
- Lyon MF. Lyonisation of the X-chromosome. Lancet. 1963;2(7317):1120-1121
- Watts G. Mary Frances Lyon. Lancet. 2015;385(9970):768
- Fisher EM, Peters J. Mary Frances Lyon (1925–2014). Cell. 2015;160(4):577-578.
- Bibliography. Lyon, Mary F. WorldCat Identities
- Millar RA, Biscoe TJ. Lyonisation of the X-chromosome. Lancet. 1963;2(7311):769-770.
- Cooper, D.N. Lionizing lyonization 50 years on. Hum Genet 130, 167–168 (2011).
the person behind the name