Evolutionary crossroads in developmental biology: annelids.

Evolutionary crossroads in developmental biology.

Variation in spiralian development: insights from polychaetes.

Spiralian development is characterized by the conservation of spindle orientation and cell geometry during early cleavage stages, as well as features of the ultimate fates of identified cells. This complex set of characters is shared by a number of animal lineages including nemerteans, polyclad platyhelminthes, annelids and mollusks. How a similar, highly stereotypical cleavage program can give...

Evolutionary crossroads in developmental biology: Dictyostelium discoideum.

Dictyostelium discoideum belongs to a group of multicellular life forms that can also exist for long periods as single cells. This ability to shift between uni- and multicellularity makes the group ideal for studying the genetic changes that occurred at the crossroads between uni- and multicellular life. In this Primer, I discuss the mechanisms that control multicellular development in Dictyost...

Annelids in evolutionary developmental biology and comparative genomics.

Annelids have had a long history in comparative embryology and morphology, which has helped to establish them in zoology textbooks as an ideal system to understand the evolution of the typical triploblastic, coelomate, protostome condition. In recent years there has been a relative upsurge in embryological data, particularly with regard to the expression and function of developmental control ge...

Arthropod-like Expression Patterns of engrailed and wingless in the Annelid Platynereis dumerilii Suggest a Role in Segment Formation

The origin of animal segmentation, the periodic repetition of anatomical structures along the anteroposterior axis, is a long-standing issue that has been recently revived by comparative developmental genetics. In particular, a similar extensive morphological segmentation (or metamerism) is commonly recognized in annelids and arthropods. Mostly based on this supposedly homologous segmentation, ...