The nonidentity of invariable positions in the cytochromescof different species

✍ Scribed by Walter M. Fitch

• Book ID: 104784915
• Publisher: Springer
• Year: 1971
• Tongue: English
• Weight: 623 KB
• Volume: 5
• Category: Article
• ISSN: 0006-2928
• DOI: 10.1007/bf00485794

✦ Synopsis

Th& study answers the question: Are the variable and invariable codons of cytochrome c largely the same in all species ? A method is presented for estimating the number of invariable (as opposed to unvaried) eodons common to two taxa. The two taxa in this study were comprised o f four fungi and four metazoans. Given the number of mutations fixed in each taxon, one calculates the number of eodons that wouM be expected to have fixed mutations in both taxa, in one taxon only, in the other taxon only, and in neither taxon. This expectation depends upon the number of invariable codons that are assumed to be common to both taxa. In the present example, the assumption of 41 invariable codons in common leads to estimates that deviate by less than 2% from the values actually observed. This leads to the conclusion that there are 46 positions that are variable in one taxon but invariable in the other, thereby demonstrating that the invariable codons are not largely the same between the fungi and the metazoans.

This project received support from NSF grant (GB-7486). The University of Wisconsin Computing Center, whose facilities were employed, also received support from NSF and other United States government agencies.