Matthias Stanke, Chi Vinh Duong, Manuela Pape, Markus Geissen, Guido Burbach, Thomas Deller, Hugues Gascan, Rosanna Parlato, Günther Schütz and Hermann RohrerDevelopment133, 141-150.

Owing to an oversight, the co-authorship of Christiane Otto was not acknowledged in the print and final online versions of this paper.

The correct author list is Matthias Stanke, Chi Vinh Duong, Manuela Pape,Markus Geissen, Guido Burbach, Thomas Deller, Hugues Gascan, Christiane Otto,Rosanna Parlato, Günther Schütz and Hermann Rohrer.

The authors apologise to readers for this mistake.