, but not , is required for cnidocyte development in the sea anemone .

BACKGROUND

genes are a family of conserved transcription factors that regulate many aspects of developmental morphogenesis, notably the development of ectodermal sensory structures including eyes. , the starlet sea anemone, has numerous orthologs, many of which are expressed early during embryogenesis. The function of genes in this eyeless cnidarian is unknown.

RESULTS

Here, we show that , but not , plays a critical role in the development of cnidocytes in . Knockdown of results in a loss of developing cnidocytes and downregulation of numerous cnidocyte-specific genes, including a variant of the transcription factor . We also demonstrate that the co-expression of in a subset of the -expressing cells is associated with the development with a second lineage of cnidocytes and show that knockdown of the neural progenitor gene results in downregulation of expression of , , and several cnidocyte-specific genes. Because is not co-expressed with at any time during cnidocyte development, we propose a simple model for cnidogenesis whereby a -expressing progenitor cell population undergoes division to give rise to -expressing cnidocytes, some of which also express .

DISCUSSION

The role of in cnidocyte development among hydrozoans has not been studied, but the conserved role of in regulating the fate of a progenitor cell that gives rise to neurons and cnidocytes in and suggests that this / pathway may well be conserved across cnidarians.