Germ cell specification and early embryonic patterning in Bombyx mori as revealed by nanos orthologues
Article first published online: 1 SEP 2008
© 2008 The Author(s). Journal compilation © 2008 Wiley Periodicals, Inc.
Evolution & Development
Volume 10, Issue 5, pages 546–554, September/October 2008
How to Cite
Nakao, H., Matsumoto, T., Oba, Y., Niimi, T. and Yaginuma, T. (2008), Germ cell specification and early embryonic patterning in Bombyx mori as revealed by nanos orthologues. Evolution & Development, 10: 546–554. doi: 10.1111/j.1525-142X.2008.00270.x
- Issue published online: 1 SEP 2008
- Article first published online: 1 SEP 2008
SUMMARY In the silkmoth Bombyx mori, the germ cells first appear from the posterior ventral side of the egg (from within the mesodermal primordium) after blastoderm formation. This is in contrast to Drosophila, where germ cells appear at the posterior pole before cellular blastoderm formation. To date, germ plasm has not been found in B. mori. In this study, we describe the identification and expression pattern of nanos from B. mori, in which we recovered four nanos orthologues. One orthologue showed strong expression in embryonic germ cells, which was traced back to periplasmic granules dispersed on the ventral midline of the egg from the posterior–ventral focus of preblastoderm embryos. This suggests that, in B. mori, as in dipterans, germ cell formation depends on a localized determinant in the egg. The expression of another orthologue was observed in the posterior of the germ band. We speculate that nanos has dual functions; one in germ cell formation and the other in posterior body patterning, which is conferred by one nanos gene in Drosophila, but is assigned to different genes in B. mori.