Comparative analysis of gene expression for convergent evolution of camera eye between octopus and human.
Although the camera eye of the octopus is very similar to that of humans, phylogenetic and embryological analyses have suggested that their camera eyes have been acquired independently. It has been known as a typical example of convergent evolution. To study the molecular basis of convergent evolution of camera eyes, we conducted a comparative analysis of gene expression in octopus and human camera eyes. We sequenced 16,432 ESTs of the octopus eye, leading to 1052 nonredundant genes that have matches in the protein database. Comparing these 1052 genes with 13,303 already-known ESTs of the human eye, 729 (69.3%) genes were commonly expressed between the human and octopus eyes. On the contrary, when we compared octopus eye ESTs with human connective tissue ESTs, the expression similarity was quite low. To trace the evolutionary changes that are potentially responsible for camera eye formation, we also compared octopus-eye ESTs with the completed genome sequences of other organisms. We found that 1019 out of the 1052 genes had already existed at the common ancestor of bilateria, and 875 genes were conserved between humans and octopuses. It suggests that a larger number of conserved genes and their similar gene expression may be responsible for the convergent evolution of the camera eye.
Center for Information Biology and DNA Data Bank of Japan, National Institute of Genetics, Mishima, 411-8540, Japan.
Atsushi
A
Ogura
Kazuho
K
Ikeo
Takashi
T
Gojobori
D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D019143:Evolution, Molecular; D020224:Expressed Sequence Tags; D005123:Eye / Q000378:metabolism; D015870:Gene Expression; D020869:Gene Expression Profiling; D015723:Gene Library; D006801:Humans; D049831:Octopodiformes / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D012689:Sequence Homology, Nucleic Acid