Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2017 Jan 20:8:ncomms14139.
doi: 10.1038/ncomms14139.

Diverse feather shape evolution enabled by coupling anisotropic signalling modules with self-organizing branching programme

Ang Li  1 , Seth Figueroa  2 , Ting-Xin Jiang  1 , Ping Wu  1 , Randall Widelitz  1 , Qing Nie  2   3 , Cheng-Ming Chuong  1   4   5   6
Affiliations

Diverse feather shape evolution enabled by coupling anisotropic signalling modules with self-organizing branching programme

Ang Li et al. Nat Commun. .

Abstract

Adaptation of feathered dinosaurs and Mesozoic birds to new ecological niches was potentiated by rapid diversification of feather vane shapes. The molecular mechanism driving this spectacular process remains unclear. Here, through morphology analysis, transcriptome profiling, functional perturbations and mathematical simulations, we find that mesenchyme-derived GDF10 and GREM1 are major controllers for the topologies of rachidial and barb generative zones (setting vane boundaries), respectively, by tuning the periodic-branching programme of epithelial progenitors. Their interactions with the anterior-posterior WNT gradient establish the bilateral-symmetric vane configuration. Additionally, combinatory effects of CYP26B1, CRABP1 and RALDH3 establish dynamic retinoic acid (RA) landscapes in feather mesenchyme, which modulate GREM1 expression and epithelial cell shapes. Incremental changes of RA gradient slopes establish a continuum of asymmetric flight feathers along the wing, while switch-like modulation of RA signalling confers distinct vane shapes between feather tracts. Therefore, the co-option of anisotropic signalling modules introduced new dimensions of feather shape diversification.

PubMed Disclaimer

Figures

Figure 1
Figure 1. Feather vane shapes vary with differential BGZ topology and barb-rachis angles.
(a) Schematic drawing of feather before and after maturation. The barb-rachis angle is a combination of the helical growth angle (θ) during branching morphogenesis and the expansion angle (β) after maturation. (b) Comparing morphologies of two types of chicken remiges with different asymmetry levels and two types of body plumes with different vane widths before and after maturation. Feather epithelial cylinder (before maturation) was cut open at the rachis side and SHH in situ hybridization was used to highlight vanes. Boxes indicate the regions magnified on the right. Vane widths and barb-rachis angles are highlighted by bars and angle symbols, respectively. Scale bars, 500 μm. (c) Quantification of the ratio of different feather epithelial regions before maturation (n=4); vane widths, barb-rachis angles and barb lengths after maturation (n=30). Error bars denote s.d. **P<0.01. (d) Emarginated primary remiges demonstrate abrupt change of vane width. Feathers growing to a point ∼1 cm distal to the emarginated notch position were collected and compared with those ∼1 cm proximal to the notch. A significant shrinkage of the BGZ was observed in those proximal to the notch. Scale bars, 500 μm. (e) Comparisons of vane widths (n=10), barb-rachis angles (n=16) and barb lengths (n=16) at positions ∼1 cm distal and proximal to the notch in mature feathers. Error bars denote s.d. **P<0.01.
Figure 2
Figure 2. Identifying key molecular regulators of feather vane shapes.
(a) Scatter plots depicting the transcriptomic comparisons between lateral and medial primary remige pulp, dorsal and breast plume pulp, respectively. Among the differentially expressed genes we picked out crucial signalling molecules (red) for further characterization. The linear correlation coefficient (r) is very close to 1, indicating highly similar transcriptome profile between samples. (b) The highlighted genes are clustered in two groups, one associated with narrower vanes and the other associated with wider vanes (L and M are the lateral side and medial side of primary remige; D, dorsal plume; B, breast plume, respectively. Two biological replicates are shown). (c) Candidate genes highlighted by RNA-seq analysis demonstrated differential localization in the pulp of growing feathers with different vane shapes (arrows). KRT75 is highly expressed in the rachis epithelium and hence was used as a marker for position alignment between samples. Scale bars, 500 μm. (d) qPCR for CYP26B1 and CRABP1 in the pulp of primary remiges along the wing (lateral-to-medial: X, IX, VII, V, III, n=3 for each position) demonstrates gradually decreased CYP26B1 expression and increased CRABP1 expression. While dorsal plumes have more strikingly elevated CYP26B1 and downregulated CRABP1 expression compared with the breast plumes (n=3). Error bars denote s.d. **P<0.01, NS, not significant.
Figure 3
Figure 3. GDF10 is a crucial modulator of rachis topology.
(a) Compared with the RCAS-GFP (control) infected neonatal primary remiges, GDF10 and BMP2 mis-expressing feathers developed enlarged rachises as shown by Hematoxylin & Eosin (H&E) staining and KRT75 in situ hybridization. Nuclear pSMAD1/5/8 positive cells also increased in the rachis region. Dotted red lines highlight the rachis. Scale bar, 100 μm. (b) RCAS-β-Catenin infected neonatal remiges developed expanded rachis without notable upregulation of GDF10 expression. Dotted red lines highlight the rachis. (c) RCAS-GDF10 infection increased nuclear β-Catenin positive cells in the pulp adjacent to the rachis. Scale bar, 100 μm.
Figure 4
Figure 4. GREM1 is a key regulator of BGZ topology.
(a) Compared with the controls, GREM1 mis-expressed adult chicken primary remiges have reduced vane width and increased BGZ width. Boxes indicate the vane boundaries between BGZ and vanes magnified below. Scale bars: 5 mm for the leftmost panel, 500 μm for the right two panels. (b) Comparing vane widths (n=4), barb-rachis angles and barb lengths (n=10) in control and GREM1 mis-expressed feathers. Error bars denote s.d. **P<0.01, *P<0.05, NS, not significant. (c) RCAS-GREM1 infected neonatal remiges not only had an expanded BGZ but also a branched rachis. Boxed regions are magnified on the right. Dotted red lines highlight the rachis. Scale bar, 100 μm. (d) GREM1 soaked beads reduced nuclear pSMAD1/5/8 staining in the neighbouring epithelial cells. Boxed regions are magnified on the top-left corner. Dashed lines highlight the beads. Scale bar, 100 μm.
Figure 5
Figure 5. RA signalling modulates vane morphology and epithelial cell shapes.
(a) Compared with the controls, RCAS-DNRARβ infected adult chicken primary remiges have significantly reduced vane width and barb-rachis angles, while BGZ width is increased. Boxes highlight vane boundaries. Scale bars: leftmost panel: 5 mm, right three panels: 500 μm. (b) Quantification of feather vane widths (n=4), barb-rachis angles and barb lengths (n=10) in control and DNRARβ infected remiges. Error bars denote s.d. **P<0.01, *P<0.05, NS, not significant. (c) BGZ epithelial cells have more elongated shape at epithelial regions exposed to lower RA levels. Phalloidin labels F-Actin that is mainly localized along epithelial cell boundaries. Scale bar, 50 μm. White lines highlight cell shape differences. (d) Quantification of cell aspect ratio and cell area in BGZ epithelial cells (n=30). Error bars denote s.d. **P<0.01, *P<0.05, NS, not significant.
Figure 6
Figure 6. RA signalling can directly inhibit GREM1 expression.
(a) Insertion of AG1x8 beads soaked in 1 mg ml−1 RA into dorsal plumes' BGZ pulp significantly decreased GREM1 expression compared with the DMSO treated controls. Dashed lines highlight the bead. Scale bar, 100 μm. (b) qPCR for GREM1 in pulp cells from four types of feathers treated with different doses of RA (n=3). Error bars denote s.d. (c) Two conserved (chicken, turkey, zebra finch) DR1 type RAREs were identified close to the GREM1 genomic locus. DR1-1 (highlighted in red) is in the active promoter region (H3K4me3 peak). The peak regions called by MACS are highlighted by blue bars. (d) DR1-1 downregulated its downstream gene expression upon RA treatment while a DR5 trimer had the opposite effect in dual luciferase assays (n=4). Error bars denote s.d. **P<0.01, NS, not significant.
Figure 7
Figure 7. A multi-module regulatory model of feather diversification.
(a) Schematic representation of the infrastructure of the multi-module regulatory feather (MRF) model and the corresponding transformative events of feather shapes in evolution. Dashed lines denote crosstalk relationships not fully confirmed. The differential equations for quantifying the crosstalk relationships are listed in the Methods. (b) Representative simulations of vane shape variations using the MRF model either without RA module, with high RA (CRABP1 level set at 1.1, CYP26B1 at 0.02, artificial unit), or with low RA (CRABP1 at 0.005, CYP26B1 at 0.2). (c) Representative simulations of feathers with different levels of vane asymmetry by changing the slope of RA gradient (CRABP1 at 0.006, CYP26B1 at 5 for the steeper RA gradient, CRABP1 at 0.03, CYP26B1 at 0.5 for the intermediate RA gradient, CRABP1 at 0.06, CYP26B1 at 0.3 for the shallower RA gradient), (d) Simulations of RCAS-GREM1 and RCAS-DNRARb infected feathers in which the BGZ expands without significantly shortening of barbs.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Prum R. O. & Brush A. H. The evolutionary origin and diversification of feathers. Q. Rev. Biol. 77, 261–295 (2002). - PubMed
    1. Xu X. et al.. An integrative approach to understanding bird origins. Science 346, 1253293 (2014). - PubMed
    1. Chuong C. M. et al.. Adaptation to the sky: defining the feather with integument fossils from mesozoic China and experimental evidence from molecular laboratories. J. Exp. Zool. B Mol. Dev. Evol. 298, 42–56 (2003). - PMC - PubMed
    1. Xu X., Zheng X. & You H. Exceptional dinosaur fossils show ontogenetic development of early feathers. Nature 464, 1338–1341 (2010). - PubMed
    1. Chiappe L. M. in Glorified Dinosaurs: The Origin and Early Evolution of Birds 263, John Wiley (2007).

Publication types