Abstract
Interactions between all three pigment cell types are required to form the stripe pattern of adult zebrafish (Danio rerio), but their molecular nature is poorly understood. Mutations in leopard (leo), encoding Connexin 41.8 (Cx41.8), a gap junction subunit, cause a phenotypic series of spotted patterns. A new dominant allele, leo(tK3), leads to a complete loss of the pattern, suggesting a dominant negative impact on another component of gap junctions. In a genetic screen, we identified this component as Cx39.4 (luchs). Loss-of-function alleles demonstrate that luchs is required for stripe formation in zebrafish; however, the fins are almost not affected. Double mutants and chimeras, which show that leo and luchs are only required in xanthophores and melanophores, but not in iridophores, suggest that both connexins form heteromeric gap junctions. The phenotypes indicate that these promote homotypic interactions between melanophores and xanthophores, respectively, and those cells instruct the patterning of the iridophores.
Highlights
Adult zebrafish (Danio rerio) display a characteristic pattern of horizontal dark and light stripes on their bodies as well as on their anal fins and tailfins (Figure 1A)
As in wildtype (Figure 1A–A′), the dark stripe regions of melanophores are covered with loose blue iridophores
Instead of dark and light stripe regions, they display variable numbers of small groups of melanophores in islands of blue iridophores, or even single melanophores distributed in an almost even background of dense iridophores covered by xanthophores characteristic for the light stripe regions (Figure 1D′,E′)
Summary
Adult zebrafish (Danio rerio) display a characteristic pattern of horizontal dark and light stripes on their bodies as well as on their anal fins and tailfins (Figure 1A). In the dark stripes of the trunk, a net of loose or blue iridophores and pale, stellate xanthophores cover the melanophores, the light stripes are composed of dense silvery iridophores covered by compact orange xanthophores (Hirata et al, 2003, 2005; Frohnhofer et al, 2013; Mahalwar et al, 2014; Singh et al, 2014). At the onset of metamorphosis, iridophores appear in the skin at the region of the horizontal myoseptum that provides a morphological pre-pattern (Frohnhofer et al, 2013). They proliferate and spread as densely connected cells to form the first light stripe. Stripe formation does not require iridophores, suggesting that the patterning mechanisms in the body and fins are different
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
