T. Kusakabe et al., Ci-opsin1, a vertebrate-type opsin gene, expressed in the larval ocellus of the ascidian Ciona intestinalis, FEBS LETTER, 506(1), 2001, pp. 69-72
A novel gene encoding visual pigment, Ci-opsin1, was identified in a primit
ive chordate, the ascidian, Ciona intestinalis. Molecular phylogenetic anal
ysis and the exon-intron organization suggest that Ci-opsin1 is closely rel
ated to the retinal and pineal opsins of vertebrates. During embryogenesis,
Ci-opsin1 transcripts were first detected in part of the brain of mid tail
bud embryos; its expression was confined to photoreceptor cells of the ocel
lus (eye spot) in the larval brain as development proceeded. These results
suggest a common descent of the ascidian ocellus and the vertebrate eyes. T
he ocellus of ascidian larvae may represent an ancestral state of the verte
brate eye. (C) 2001 Federation of European Biochemical Societies, Published
by Elsevier Science B.V. All rights reserved.