Current Genetics

, Volume 32, Issue 4, pp 296–299

A deviant mitochondrial genetic code in prymnesiophytes (yellow-algae): UGA codon for tryptophan

  • Y. Hayashi-Ishimaru
  • Megumi Ehara
  • Yuji Inagaki
  • T. Ohama
ORIGINAL PAPER

DOI: 10.1007/s002940050280

Cite this article as:
Hayashi-Ishimaru, Y., Ehara, M., Inagaki, Y. et al. Curr Genet (1997) 32: 296. doi:10.1007/s002940050280

Abstract

The sequence of a representative mitochondrial gene COXI, encoding cytochrome c oxidase subunit I, was determined in five species that cover all the orders of the Prymnesiophyta with the exception of the Pavlovales. Through this analysis, we noticed that the `stop' codon UGA appears frequently and, specifically, at conserved tryptophan (Trp) sites of the gene. We showed these sites were not edited in the corresponding mRNA in one of these species, Isochrysis galbana. Therefore, it is most likely that the UGA codon is used for Trp, and not as a stop codon, in prymnesiophytes. All the analyzed prymnesiophytes made a tight cluster on the COXI phylogenetic tree which includes representative species of green-algae, land plants, yellow-green algae, eustigmatophytes and a red-alga. This suggests a monophyletic origin for the prymnesiophytes. The same deviant genetic code, i.e. UGA for Trp, has also been found in the red-alga, Chondrus crispus. In spite of the fact that this red-alga and the prymnesiophytes, share the same deviant genetic code for Trp, close affinity between the two groups was not statistically supported by the phylogenetic analysis of COXI sequences.

Key words PrymnesiophytaDeviant genetic codeCytochrome c oxidase subunit IThe codon-capture theory

Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • Y. Hayashi-Ishimaru
    • 1
  • Megumi Ehara
    • 2
  • Yuji Inagaki
    • 1
  • T. Ohama
    • 1
  1. 1.Biohistory Research Hall, 1-1 Murasaki-cho, Takatsuki, Osaka 569-11, JapanJP
  2. 2.Department of Biology, Faculty of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560, JapanJP