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Chapter 25 : Adventures with Mutation and Selection in Beehive and Cow Country
This chapter presents some personal memories and reflections from Diarmaid Hughes (D.H.) and Dan Andersson (D.I.A.) based on three decades of knowing John Roth. The thesis provided some new insights into the translation process, identifying several mutant tRNAs that could suppress a −1 frameshift mutation by reading a base doublet as a codon, and mutants of EF-Tu that increased frameshifting and nonsense suppression by normal tRNAs. Coming to the John's lab, everything was the same but all the people had been turned over. At this time John had become interested in the controversial area of adaptive mutations. In an article in Nature in 1988, Cairns and coworkers suggested that some mutations are induced in response to selection rather than being formed randomly irrespective of selective conditions as proposed by the early work of Luria, Delbruck, and Lederberg. This work established a collaboration that has been and is still ongoing regarding the role of gene amplification in the Cairns system and, more important, the significance of gene amplification during adaptation and evolution of new genes. After Dan Andersson returned to Uppsala from his first postdoc stint in John’s lab, there was a period when D.H. and Dan were both looking for something new to do in bacterial genetics and met for a discussion. The simple experiments with Salmonella demonstrated convincingly that carbon starvation did not cause any increase in the frequency of mutations (in contrast to what was generally assumed or claimed in that field).