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Brenner, Sydney

system nervous codons code

(1927– ) South African–British molecular biologist: co-discoverer of triplet nature of genetic codons.

Brenner’s parents had emigrated to South Africa from Russia and Lithuania. He qualified in medicine and medical biology at Johannesburg and then became a research student with at Oxford, working on bacteriophage. In 1957 he joined the Medical Research Council’s Molecular Biology Laboratory at Cambridge, becoming its director 1979–86.

In the 1950s Brenner did notable work in showing that the triplets (codons) of bases in DNA chains, each of which were believed to code for a specific amino acid destined for protein synthesis, do not form an ‘overlapping’ code. Thus in a sequence … ATCGCATAG … the codons could be ATC, GCA, TAG … but not ATC, TCG, CGC . . . . By 1961 Brenner, and others had confirmed that codons are triplets (and not, for example, quadruplets) and that neither overlapping nor ‘punctuation marks’ appeared to exist in the code. In the same year Brenner and others also demonstrated that the ribosomes, which require an instructional code to carry out their task of protein synthesis, receive it in the form of a special type of RNA, messenger RNA (mRNA).

In the 1970s he began intensive studies of the nervous system of a type of nematode worm. Although less than 1 mm long, its nervous system is complex and roughly 100 genes contribute to the make-up of its nervous system, which has about 300 neurones and so is usefully intermediate between Escherichia coli (1 neurone) and man (10 10 neurones). Most mutants of the worm show variations in the nervous system which can be informative, and Brenner’s work involved slicing a worm into up to 20 000 serial sections for electron microscopy in order to define the anatomy of the system and ultimately to relate molecular biology to its visible structure and development.

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