Professor J. R. S. Fincham

Biochemical geneticist specialising in fungi

J. R. S. Fincham was distinguished for his pioneering contributions to biochemical genetics and microbial genetics. In the 1940s and early 1950s, George Beadle, Edward Tatum and Joshua Lederberg launched the new field of microbial genetics (for which they were awarded the Nobel Prize in 1958). It was discovered that single gene mutations blocked single metabolic steps and this led to the "one gene-one enzyme" hypothesis. This powerful prediction was not supported by experiment for some years, and it was John Fincham who first obtained direct evidence that it was correct, using am mutants in the fungus Neurospora crassa that were deficient in a specific enzyme (glutamate dehydrogenase). He exploited these mutants and the gene product in many biochemical and genetic studies for much of the rest of his career.

John Robert Stanley Fincham, geneticist: born Southgate, Middlesex 11 August 1926; Bye-Fellow, Peterhouse, Cambridge 1949-50, Professorial Fellow 1984-91 (Emeritus Fellow); Lecturer in Botany, University College, Leicester (from 1957 Leicester University) 1950-54, Reader in Genetics 1954-60; Head of Department of Genetics, John Innes Institute 1960-66; Professor of Genetics, Leeds University 1966-76; FRS 1969; Editor, Heredity 1971-78; Buchanan Professor of Genetics, Edinburgh University 1976-84, Honorary Fellow, Division of Biology 1992-2005; FRSE 1978; President, Genetical Society 1978-81; Arthur Balfour Professor of Genetics, Cambridge University 1984-91 (Emeritus); married 1950 Ann Emerson (one son, three daughters); died Edinburgh 9 February 2005.

J. R. S. Fincham was distinguished for his pioneering contributions to biochemical genetics and microbial genetics. In the 1940s and early 1950s, George Beadle, Edward Tatum and Joshua Lederberg launched the new field of microbial genetics (for which they were awarded the Nobel Prize in 1958). It was discovered that single gene mutations blocked single metabolic steps and this led to the "one gene-one enzyme" hypothesis. This powerful prediction was not supported by experiment for some years, and it was John Fincham who first obtained direct evidence that it was correct, using am mutants in the fungus Neurospora crassa that were deficient in a specific enzyme (glutamate dehydrogenase). He exploited these mutants and the gene product in many biochemical and genetic studies for much of the rest of his career.

John Robert Stanley Fincham was born in 1926, the son of a nurseryman father and schoolteacher mother, and educated at Hertford Grammar School and Peterhouse, Cambridge, where he read Natural Sciences. After his first degree he studied for a PhD under the supervision of D.G. Catcheside in the Botany School, Cambridge, a laboratory that produced several influential geneticists. During his postgraduate research he worked for one year at the California Institute of Technology with Sterling Emerson, in a laboratory that was the stronghold of Neurospora genetics. In 1950, the year he married Emerson's daughter Ann, he became a Lecturer and, from 1954, Reader at University College, Leicester (granted its Royal Charter as Leicester University in 1957), moving in 1960 to head the Genetics Department of the John Innes Institute. He went to Leeds University in 1966, as the first Professor of Genetics. Ten years later he was appointed to the Buchanan Chair of Genetics at Edinburgh University, and then, in 1984, to the Balfour Chair of Genetics at Cambridge University - he was the only geneticist to have held both these prestigious professorships.

He was elected a Fellow of the Royal Society in 1969, and a Fellow of the Royal Society of Edinburgh in 1978. He was awarded the Emil Christian Hansen Medal in 1977. He retired in 1991, returned to Edinburgh and remained active in teaching and research.

In the late 1950s, an unexpected discovery was made in several laboratories. This was that the fact that some mutations in the very same gene complemented each other to produce enzyme activity, whereas it was previously thought that only mutations in different genes should complement each other. Fincham exploited his am mutant system to demonstrate for the first time that this complementation was due to the formation of enzymes with at least two protein sub-units (in his case six sub-units), where different mutations in separate sub-units corrected each others' deficiency to produce enzyme activity. Fincham reviewed all this work, and much else, in his book Genetic Complementation (1966).

Microbial genetics gave rise to modern molecular genetics, and Fincham was quick to exploit these new techniques to gain many new insights into gene structure and function. The am gene was cloned and sequenced, which resulted in the discovery of a non-coding DNA sequence or intron, one of the first to be identified in fungi. He exploited the surprising discovery that duplicated regions of DNA in Neurospora have their sequences altered at one point in the life cycle, and this could be used to isolate new am mutations.

Fincham had a voluminous knowledge of genetics, and was a fluent author. In 1963 he produced with P.R. Day the highly successful Fungal Genetics, which was expanded in subsequent editions (with A. Radford as co-author of the last, 1979, edition). He also wrote other textbooks on genetics, and several influential reviews.

At the John Innes Institute, B.J. Harrison was studying the genetics of Antirrhinum, and was particularly interested in the properties of certain unstable genes. These had earlier been studied in great detail in maize by Barbara McClintock (Nobel prizewinner in 1983), but most geneticists found it difficult to understand either her experiments or the great significance of the results. Fincham was one of the few who did so, and (with G.R. Sastry) wrote an important review of the subject.

He had embarked on a successful collaboration with Harrison on the genetics of unstable or mutable alleles. These studies were continued at the John Innes at its new location at the University of East Anglia, and Antirrhinum was later launched as a model system for the study of the molecular and developmental genetics of plants. Another of his strong interests was genetic recombination, namely, the way chromosomes with slightly different DNA sequences interact with each other to produce new sequences.

Fincham's interests outside science included mountaineering and music, and he played rugby, cricket and squash.

Robin Holliday