Two discoveries undermined these convictions. In 1965, Zuckerkandl and Pauling were working on the evolution of protein sequences. At a meeting on evolving genes and proteins, they put forward the principle of the ‘evolutionary clock’, stating that amino-acid replacements in proteins accumulate between species according to a Poisson process [35]. The following year, Harris [36] and Hubby and Lewontin [37] used protein electrophoresis and showed that polymorphism could be recorded at a number of enzyme loci without a priori knowledge of differences between alleles. They reported very high levels of heterozygosity (12 % in Drosophila) allowing Lewontin and Hubby [38] to conclude that available models of natural selection could not explain protein polymorphisms. The number of genetic deaths was greater than the reproductive excess of even the most prolific species. In 1968, Kimura [22] put forward the neutral theory of molecular evolution as a solution to this paradox. He did not reject the existence of selection, but claimed that it contributed relatively little to observed molecular changes. “The neutral theory is not antagonistic to the cherished view that the evolution of form and function is guided by Darwinian selection, but it brings out another facet of the evolutionary process by emphasizing the much greater role of mutation pressure and random drift at the molecular level” ([39] p. IX, my emphasis). TÉcnica princiapal Protein electrophoresis Analyzing protein structure and function using ancestral gene reconstruction Current Opinion in Structural Biology Volume 20, Issue 3, June 2010, Pages 360–366 Nucleic acids / Sequences and topology Michael J Harms <img src="http://origin-cdn.els-cdn.com/sd/entities/REemail.gif" alt="E-mail the corresponding author">, Joseph W Thornton <img src="http://origin-cdn.els-cdn.com/sd/entities/REemail.gif" alt="E- mail the corresponding author"> Howard Hughes Medical Institute, Center for Ecology and Evolutionary Biology, 335 Pacific Hall, 5289 University of Oregon, Eugene, OR 97403, United States Protein electrophoresis is a method for analysing the proteins in a fluid or an extract. The electrophoresis may be performed with a small volume of sample in a number of alternative ways with or without a supporting medium: SDS polyacrylamide gel electrophoresis (in short gel electrophoresis, PAGE, or SDS-electrophoresis, free flow electrophoresis, electrofocusing,isotachophoresis, affinity electrophoresis, immunoelectrophoresis, counterelectrophoresis, and capillary electrophoresis). http://dx.doi.org/10.1016/j.sbi.2010.03.005, How to Cite or Link Using DOI
