Gene expression profiles in Ciona intestinalis cleavage-stage embryos.

A total of 1612 expression sequence tags derived from Ciona intestinalis cleavage-stage embryos were examined to explore detailed gene expression profiles. The 3' sequences indicate that the 1612 clones can be categorized into 1066 independent clusters. DDBJ database search suggested that 496 of them showed significant matches to reported proteins with distinct functions. Among them 69 are associated with cell-cell communications and 41 with transcription factors. In situ hybridization of all 1066 clusters showed that 84 clusters exhibited blastomere-specific pattern of expression, and many of these genes seem to encode for novel proteins. One of the interesting findings is that most of them were expressed in the precursor cells of multiple tissues. Among them 28 genes were expressed in the marginal zone of the 32-cell embryo. The blastomeres in this region are thought to receive an inductive signal from the vegetal blastomeres. Many of the blastomere-specific genes did not show similarity to known proteins. The present analysis therefore provides new information for further analyses on the cell fate specification in the Ciona embryo.