The evolutionary emergence of cell type-specific genes inferred from the gene expression analysis of Hydra

Shan Hwang Jung, Hajime Ohyanagi, Shiho Hayakawa, Naoki Osato, Chiemi Nishimiya-Fujisawa, Kazuho Ikeo, Charles N. David, Toshitaka Fujisawa, Takashi Gojobori

Research output: Contribution to journalArticlepeer-review

61 Citations (Scopus)

Abstract

Cell lineages of cnidarians including Hydra represent the fundamental cell types of metazoans and provides us a unique opportunity to study the evolutionary diversification of cell type in the animal kingdom. Hydra contains epithelial cells as well as a multipotent interstitial cell (I-cell) that gives rise to nematocytes, nerve cells, gland cells, and germ-line cells. We used cDNA microarrays to identify cell type-specific genes by comparing gene expression in normal Hydra with animals lacking the I-cell lineage, so-called epithelial Hydra. We then performed in situ hybridization to localize expression to specific cell types. Eighty-six genes were shown to be expressed in specific cell types of the I-cell lineage. An additional 29 genes were expressed in epithelial cells and were down-regulated in epithelial animals lacking I-cells. Based on the above information, we constructed a database (http://hydra.lab.nig. ac.jp/hydra/), which describes the expression patterns of cell type-specific genes in Hydra. Most genes expressed specifically in either I-cells or epithelial cells have homologues in higher metazoans. By comparison, most nematocyte-specific genes and approximately half of the gland cell- and nerve cell-specific genes are unique to the cnidarian lineage. Because nematocytes, gland cells, and nerve cells appeared along with the emergence of cnidarians, this suggests that lineage-specific genes arose in cnidarians in conjunction with the evolution of new cell types required by the cnidarians.

Original languageEnglish
Pages (from-to)14735-14740
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume104
Issue number37
DOIs
Publication statusPublished - 2007 Sep 11
Externally publishedYes

Keywords

  • Cnidarian
  • Database
  • Epithelial hydra
  • Microarray
  • Nematocyte

ASJC Scopus subject areas

  • General

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