nanos function is essential for development and regeneration of planarian germ cells

Yuying Wang, Ricardo M. Zayas, Tingxia Guo, Phillip A. Newmark

Research output: Contribution to journalArticlepeer-review


Germ cells are required for the successful propagation of sexually reproducing species. Understanding the mechanisms by which these cells are specified and how their totipotency is established and maintained has important biomedical and evolutionary implications. Freshwater planarians serve as fascinating models for studying these questions. They can regenerate germ cells from fragments of adult tissues that lack reproductive structures, suggesting that inductive signaling is involved in planarian germ cell specification. To study the development and regeneration of planarian germ cells, we have functionally characterized an ortholog of nanos, a gene required for germ cell development in diverse organisms, from Schmidtea mediterranea. In the hermaphroditic strain of this species, Smed-nanos mRNA is detected in developing, regenerating, and mature ovaries and testes. However, it is not detected in the vast majority of newly hatched planarians or in small tissue fragments that will ultimately regenerate germ cells, consistent with an epigenetic origin of germ cells. We show that Smed-nanos RNA interference (RNAi) results in failure to develop, regenerate, or maintain gonads in sexual planarians. Unexpectedly, Smed-nanos mRNA is also detected in presumptive testes primordia of asexual individuals that reproduce strictly by fission. These presumptive germ cells are lost after Smed-nanos RNAi, suggesting that asexual planarians specify germ cells, but their differentiation is blocked downstream of Smed-nanos function. Our results reveal a conserved function of nanos in germ cell development in planarians and suggest that these animals will serve as useful models for dissecting the molecular basis of epigenetic germ cell specification.

Original languageEnglish (US)
Pages (from-to)5901-5906
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number14
StatePublished - Apr 3 2007


  • Epigenesis
  • Germ cell specification
  • Platyhelminthes
  • RNA interference
  • Schmidtea mediterranea

ASJC Scopus subject areas

  • General

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