The striped pattern of the zebrafish skin offers an excellent model system in which to study biological pattern formation. Previous studies have shown that the interactions between melanophores and xanthophores are crucial for pattern formation, but little is known regarding the molecular mechanisms that regulate this phenomenon. Now, on , Shigeru Kondo, Masakatsu Watanabe and colleagues uncover a role for long-range Delta/Notch signalling between the melanophore and xanthophore pigmented cell types that is crucial for proper stripe formation. The authors show that Delta/Notch signalling is required for melanophore survival, since disruption of the pathway by DAPT treatment results in loss of melanophores, while constitutive Notch activation in transgenic fish rescues this effect. The authors use targeted laser ablation to show that the source of this survival signal is the xanthophore. Interestingly, the authors observe long protrusions that originate from the melanophores and extend to the xanthophores, which might serve as a means to mediate the Delta/Notch signalling over long distances.
