vasa and nanos expression patterns in a sea anemone and the evolution of bilaterian germ cell specification mechanisms

Evol Dev. May-Jun 2005;7(3):201-15. doi: 10.1111/j.1525-142X.2005.05023.x.

Abstract

Most bilaterians specify primordial germ cells (PGCs) during early embryogenesis using either inherited cytoplasmic germ line determinants (preformation) or induction of germ cell fate through signaling pathways (epigenesis). However, data from nonbilaterian animals suggest that ancestral metazoans may have specified germ cells very differently from most extant bilaterians. Cnidarians and sponges have been reported to generate germ cells continuously throughout reproductive life, but previous studies on members of these basal phyla have not examined embryonic germ cell origin. To try to define the embryonic origin of PGCs in the sea anemone Nematostella vectensis, we examined the expression of members of the vasa and nanos gene families, which are critical genes in bilaterian germ cell specification and development. We found that vasa and nanos family genes are expressed not only in presumptive PGCs late in embryonic development, but also in multiple somatic cell types during early embryogenesis. These results suggest one way in which preformation in germ cell development might have evolved from the ancestral epigenetic mechanism that was probably used by a metazoan ancestor.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Biological Evolution*
  • Body Patterning
  • Cloning, Molecular
  • Evolution, Molecular
  • Female
  • Gene Expression Regulation, Developmental*
  • Germ Cells / cytology*
  • Germ Cells / metabolism*
  • Mesentery / cytology
  • Mesentery / embryology
  • Molecular Sequence Data
  • Phylogeny
  • RNA Helicases / chemistry
  • RNA Helicases / genetics
  • Reproduction
  • Sea Anemones / embryology*
  • Sea Anemones / genetics*
  • Sea Anemones / growth & development
  • Sequence Alignment

Substances

  • RNA Helicases