as a feather develops, the feather bud

Control (A) and -catenin virus-infected embryos (B) were harvested at day 13 of incubation to examine feather morphology. Activation of the -catenin pathway is more uniformly distributed within a region of developing epidermis in the transgenic mouse, while in our experiments the pathway is activated in small groups of cells. Thus we conclude that forced activation of the -catenin pathway in the ectoderm induces expression of a battery of placodal genes directly and circumvents the requirement for dense dermis to generate the signal that normally activates this pathway in the epidermis. J Exp Zool (Mol Dev Evol) 298B:7390, Prum RO, Williamson S (2001) Theory of the growth and evolution of feather shape. However, concomitant with the first hair cycle, new hair follicles were induced in interfollicular skin. Expression of activated -catenin in the ectoderm induces both BMP-2 and Shh expression. Chick feather buds develop sequentially in a hexagonal array. Alteration of the pattern of -catenin signaling leads to abnormally oriented buds as well as growths on the feather filaments. J Ornithol 78:328376, Doucet SM, Shawkey MD, Hill GE, Montgomerie R (2006) Iridescent plumage in satin bowerbirds: structure, mechanisms and nanostructural predictors of individual variation in colour. While both lack the N-terminal domain of -catenin, ours also lacked the C-terminal domain which is retained in the mouse experiment. Loss of function experiments required to resolve this issue have not been performed in chick skin. Thirteen years on from its launch, the Node continues to be a place to share research stories, opinions, job adverts and event listings. Activation of placodal and dermal condensation markers. Since the same response is observed when stabilized -catenin is expressed in the ectoderm of normally apteric regions, activation of this pathway is sufficient for placode induction and does not require the cooperation of some other signal normally expressed specifically in the forming tracts. 2.3d), after which the symmetric short buds will develop into asymmetric elongated buds (Chen et al. Sections through the anterior (F) and posterior (G) of a bud along the mediolateral axis reveal strong nuclear staining in the ectoderm and dermis respectively, while the pathway is inactive in immediately adjacent cells in the dermis (F) and ectoderm (G). A. M., unpublished data). Molecular evidence for an activator-inhibitor mechanism in - PNAS Annu Rev Earth Planet Sci 33:277299, Prin F, Dhouailly D (2004) How and when the regional competence of chick epidermis is established: feathers vs. scutate and reticualte scales, a problem en route to a solution. Control of the sequence of pattern formation, Dermo-epidermal interactions between birds and mammals: differentiation of cutaneous appendages, Formation of cutaneous appendages in dermo-epidermal recombinationsbetween reptiles, birds and mammals, Regional specification and cross-species signals, Embryonic axis induction by the armadillo repeat domain of beta-catenin: evidence for intracellular signaling, Reconstruction of skin in the chorioallantoic membrane from suspensions of chick and mouse skin cells, Aggregation in vivo of dissociated cells. In early stages of infection, the expression of these two genes appears co-extensive. It is noteworthy that when induced and maintained by forced activation of the -catenin pathway, an ectodermal placode can recruit dermal cells in apteric regions to form a bud. J Exp Zool (Mol Dev Evol) 322B:240255, Foth C (2009) Die Morphologie des Erstlingsgefieders ausgewhlter Vogeltaxa unter Bercksichtigung der Phylogenie. However, a significant difference between these experiments was the fact that no effects were observed in embryonic mouse skin and ectopic hair follicles were not induced in interfollicular skin until the first hair cycle. Forced expression of Shh in the ectoderm can also promote the formation of feather buds (Ting-Berreth and Chuong, 1996; Morgan et al., 1998). Fig. Ectopic buds were also formed in the interfollicular regions of the feather tracts as well. The pattern of endogenous -catenin staining is consistent with roles in both bud initiation and subsequent bud outgrowth. An alternative explanation of this co-localization is that TCF-1 expression is induced by -catenin signaling. However, preferential infection of the ectoderm of the feather bud primordia compared to interfollicular skin is observed after the dermal condensation has formed and the bud rudiment has begun to protrude from the ectoderm. However, as anterior/posterior distinctions arise in the bud, the sharp boundary between cells with strong nuclear -catenin staining in the anterior placode and those with cell surface staining in the posterior of the placode is unlikely to be caused by local expression of ligand. 8C), but this lag suggests that this induction is an indirect effect of infection. Representative samples were also sectioned to confirm the localization of induced gene expression to the ectoderm or dermis. The dorsal feathers develop in a posterior to anterior and medial to lateral sequence. Physical manipulations which alter bud polarity lead to corresponding changes in Delta and Serrate gene expression and confirm their utility as markers of polarity (Chen et al., 1997). Analogous constructs with or without the C-terminal domain behave in a similar fashion in forced expression assays in Xenopus and Drosophila (Funayama, et al., 1995; Orsulic and Peifer, 1996). Note the accumulation of -catenin in the cytoplasm in the anterior dermal condensation (E red arrow) and nuclear accumulation of -catenin in the posterior dermal condensation (E, underlying the vertical red arrows). Proc Natl Acad Sci U S A 100:1257612578. This nuclear staining in the dermis is transient and is largely absent from a corresponding region a day later in development (B). John Murray, London, Davies HR (1889) Die Entwicklung der Feder und ihre Beziehungen zu anderen Integumentgebilden. This expression is initially evenly distributed between presumptive follicular and interfollicular regions during the earliest stages of tract formation and becomes localized to the bud ectoderm (Notch-1) and dermis (Delta-1) or interbud (Notch-2) as they are formed. BMP-2 is expressed in both the epidermal placode and the dermal condensation as they form and is an inhibitor of bud formation that contributes to the spacing between initiating buds as well as the subsequent patterning within each individual feather (Jung et al., 1998; Noramly and Morgan, 1998). We thank C. Tabin, R. Johnson and H. Clevers for reagents and P. Goetinck and D. Fekete for comments on the manuscript. As shown in Fig. The feathers in the femoral tract of a control embryo (E) are long and thin compared to a similar region in an injected embryo (F). The John Hopkins University Press, Baltimore, Chuong C, Edelman GM (1985) Expression of cell-adhesion molecules in embryonic induction. A Feather's Tale From tube to plane and back again - TDL This response is observed both within the tracts and in the normally apteric regions. The embryonic development of feathers starts with the formation of feather tracks in particular body regions, the pterylae, which usually develop down-like feathers, so-called neoptile or natal downs, as first feather generation (Lucas and Stettenheim 1972; Foth 2011).In these areas, the skin forms parallel rows of placodes, which are local thickening of dermis and epidermis (Lucas and . The development of the feather, showing absence of cruelty in clipping and quilling. These chickens develop long feathers as seen in roosters . Endogenous -catenin was detected with a monoclonal antibody (15b8, Sigma) diluted 1:500 in PBST followed by secondary detection with fluorescein-conjugated anti-mouse IgG. In the apteric regions, ectopic placodal gene expression and morphological changes are observed in the absence of detectable changes in either -catenin localization or cell density in the dermis (Fig. At the tip of the developing limb bud is a ridge of thick-ened epithelium, known as the apical ectodermal ridge, which plays a key role. PubMed Regulated activation of BMP-2 and Shh transcripts in -catenin-infected embryos. The localization and spread of the virus during patterning of the feather field was determined by detecting viral transcripts in embryos at day 6 to day 9 of incubation (Fig. ch 21 Flashcards | Quizlet Front Zool 4:23, Barrett PM, Evans DC, Campione NE (2015) Evolution of dinosaur epidermal structures. Assessing Risk of Bias and Confounding in Observational Studies of Interventions or Exposures: Further Development of the RTI Item Bank. Reciprocal interactions between these two signaling centers cause the subsequent outgrowth and patterning of the bud. Nuclear stain (red) and endogenous -catenin (green) are shown in H and J, while infection is revealed in blue on the same sections (I,K) during an early response (H,I) and as a dermal condensation is forming (J,K). Mice lacking Lef-1 have fewer hair follicles and lack whiskers (van Genderen et al., 1994). Among extant vertebrates, the feathers of modern birds are morphologically the most complex integumentary structure with enormous shape diversity resulting from a hierarchical organization of repetitive morphological and developmental modules. This signal integration must occur downstream of -catenin stabilization in the pathway. synonyms. 2018b ). This temporal and spatial correlation is consistent with a role for the -catenin pathway in mediating the primary inductive signal from the dermis which initiates patterning in the ectoderm. (E) BMP-2 transcripts are seen throughout the induced epidermal placode and are upregulated along the anterior border of the bud (the region to the left of the arrowhead). (B) Subsequent analysis of the embryo for BMP-2 transcripts showed them to be more extensive than the ectopic Shh expression and upregulated in the anterior of induced bud-like areas. Then, due to the de novo expression of Notch ligand (Delta-1, Serrate-1) and Notch-1 on the posterior and central region of the outgrowing feather bud, an A-P molecular asymmetry emerges (Fig. (A) At day 10 of incubation, feather buds point in a posterior direction revealed by the stripes of Shh expression which run along the proximal/distal axis of the feather bud. BMP-2 is among the genes induced by the activation of the -catenin pathway in the ectoderm and we assume a secondary activator of bud development, possibly an FGF, is induced as well. The -catenin virus-infected embryos show ectopic cutaneous appendages in the apteria (D). The segregation of -catenin signaling to the anterior of the placode and the posterior of the dermal condensation suggests roles in the oriented outgrowth of the bud at later stages as well. This led the authors to conclude that a second factor, in conjunction with stabilized -catenin, was required for the induction of hair follicles. Condor 99:4757, Duerden JE (1913) Experiments with ostriches. continue to refine. Exogenous FGF can also promote feather bud formation in wild-type skin (Widelitz et al., 1996). Circles of Wnt7a expression are induced by ectopic -catenin expression in the developing chick skin (arrowheads). It is down-regulated at the posterior side of the epidermis in the elongated feather buds (arrows in Figs. The fact that forced stabilization of -catenin can override lateral inhibition and elicit a placodal response in interfollicular ectoderm further suggests that lateral inhibition acts upstream of this step. continue to strengthen. Of these, 13 were harvested at day 6 of incubation, 9 at day 7, 6 at day 8 and 3 at day 9. Proc R Soc B 278:20982104, Storch V, Welsch U (1997) Systematische Zoologie. However, we have postulated that the initial inductive signal from the dermis is only generally localized in a broad band, and that patterning in the ectoderm limits the response to this signal and specifies the position and extent of the nascent placodes (Noramly and Morgan, 1998). Philos Trans R Soc Lond Ser B 226:143188, Hudon J (2005) Considerations in the conservation of feathers and hair, particularly their pigments. open access ABSTRACT -Catenin signaling has been reported to initiate feather bud development. Physiol Zol 14:103133, Livezey BC (2003) Evolution of flightlessness in rails (Gruiformes: Rallidae): phylogenetic, ecomorphological, and ontogenetic perspectives. BMP-4, BMP-7, and Serrate-1 are expressed in the forming dermal condensation but not in uninduced or interfollicular dermis (Chen et al., 1997; Crowe et al., 1998; Morgan et al., 1998; Noramly and Morgan, 1998). It appears that the integration of signaling to modulate responsiveness acts upstream of -catenin since most activities of the stabilized construct do not appear restricted within the bud. In: Currie PJ, Koppelhus EB, Shugur MA, Wright JL (eds) Feathered dragons. Here, the feathers are misshappen and are oriented randomly. 1C). These observations demonstrate that the -catenin signaling pathway can have potent effects on the development of post-natal skin, but they also indicate that widespread activation of this pathway in the epidermis has little effect on the morphogenesis of skin in the mouse embryo. From (i) to (iii), there is a gradual increase in morphological complexity, reflecting the order of appearance during development. Effect of state of differentiation of cells on feather development in hybrid aggregates of embryonic mouse and chick skin cells, A common ancestor of the mammalian transcription factors TCF-1 and TCF-1/Lef-1 expressed in chicken T cells, De Novo hair follicle morphogenesis and hair tumors in mice expressing a truncated -catenin in skin, Tissue interaction in the scaleless mutant and the use of scaleless as an ectodermal marker in studies of normal limb differentiation, Propagation and localization of Wnt signaling, Modulation of transcriptional regulation by LEF-1 in response to Wnt-1 signaling and association with -catenin, Dorsal-ventral signaling in limb development, Complementary and mutually exclusive activities of decapentaplegic and wingless organize axial patterning during Drosophila leg development, Local inhibitory action of BMPs and their relationships with activators in feather formation:Implications for periodic patterning, Lef1 expression is activated by BMP-4 and regulates inductive tissue interactions in tooth and hair development, Neural crest induction in Xenopus: evidence for a two-signal model, Expression of Radical fringe in limb-bud ectoderm regulates apical ectodermal ridge formation, The role of somitic mesoderm in the development of dorsal plumage in chick embryos. At E10, ADAM12 is in the anterior and posterior mesenchyme of midline dorsal tract feathers. 2C-F. -catenin virus-infected embryos showed areas of ectopic Shh expression both in the normally apteric region (B, arrowhead) and within the tract. 1D). Springer, Berlin, Stavenga DG, Leertouwe HL, Marshall NJ, Osorio D (2011) Dramatic colour changes in a bird of paradise caused by uniquely structured breast feather barbules. FGFs can activate feather formation in cultured explants of skin from the scaleless mutant chick (Song et al., 1996). The review was supported by the Swiss National Science Foundation grant PZ00P2_174040. The expression of Shh in control (A) and -catenin virus-infected (B) femoral tracts at day 9 of incubation. Although FGF-2 and -4 are expressed in the epidermal placode (Nohno et al., 1995; Song et al., 1996; Jung et al., 1998), their expression has not been detected prior to placode formation. 1996, Jiang . Widespread ectopic expression of Shh in the tract can be seen. (B) In -catenin-infected embryos of a similar age, many buds are abnormally oriented. . Morphology and proliferation during early feather development Differential activation between placodal cells and their neighbors may be required to allow further development along the placodal fate. 2 M-O and 3 Y, A'). Nuclear and cytoplasmic -catenin is observed in a broad swath through the lateral ectoderm and no discernible difference in -catenin levels distinguishes between presumptive placode and interfollicular fates (Fig. Cytoplasmic -catenin then accumulates and translocates to the nucleus, where it can bind to transcription factors of the T-cell factor/lymphoid enhancer binding factor-1 (TCF/Lef-1) family and modulate gene expression (reviewed by Clevers and van de Wetering, 1997). The domains of Wnt7a and -catenin nuclear localization are complementary at this stage (Fig. homologous structures vestigial structures hemiologous structures homologous structures Evolving a Protofeather and Feather Diversity - JSTOR Visit our virtual forest to learn more. Although stabilized -catenin is expressed throughout the induced placode, BMP-2 and Shh are differentially expressed across its extent at later stages of development. The detected changes in gene expression in the dermis (e.g. Molecular Biology of Feather Morphogenesis: A Testable Model for Evo Localized infection of the ectoderm was employed to alter -catenin signaling in this layer at the onset of feather development. Staining is brightest in cells immediately adjacent to the epidermis and decreases rapidly over the distance of several cell diameters from the surface, while loose mesenchyme beneath this layer does not exhibit nuclear -catenin accumulation (Fig. In the embryonic chicken skin, feather buds and the intervening interbud tissue form in a reiterated and sequential pattern that is dependent on interactions between the epidermis and dermis. Int J Dev Biol 48:137148, Prum RO (1999) Development and evolutionary origin of feathers. 6E). Z Morphol Anthropol 4:149178, Xu X, Guo Y (2009) The origin and early evolution of feathers: insights from recent paleontological and neontological data. The disorganized appearance of the feather tracts in infected embryos suggests that either the normal sequential addition of buds was perturbed, that growth rates within individual buds were altered, or both. During normal feather bud development, Shh is expressed initially in a subset of the BMP-2-expressing cells (Morgan et al., 1998 and data not shown). Generation of bioengineered feather buds on a reconstructed chick skin We are now accepting proposals for our 2025 Biologists Workshops programme. However, since the inductive signals which initiate cutaneous appendage formation are conserved between birds and mammals (Garber and Moscona, 1964; Garber et al., 1968; Dhouailly, 1973; Dhouailly et al., 1998), the fact that hair follicle morphogenesis initiates normally in the skin of mouse embryos lacking Shh supports the conclusion that Shh is only required at later stages of cutaneous appendage development (St.-Jacques et al., 1999; Chiang et al., 1999). Altmetric, Part of the Fascinating Life Sciences book series (FLS). The localization of -catenin to the nucleus of cells adjacent to the ectoderm as dense dermis forms suggests a role for the pathway in stimulating this step. Evolution 57:397405, CrossRef As the dermal condensation forms, cytoplasmic staining of -catenin is observed but no nuclear accumulation is detected (Fig. The . We find that, in most feather buds, Shh is not expressed until after both the dermal condensation and ectodermal placode have formed and conclude that it is not required for the initial specification of feather placodes although it does serve as a secondary inducer within the bud by signaling to both the ectodermal and dermal components (Morgan et al., 1998). This pattern of nuclear -catenin localization suggests a role for the pathway in several steps of tract morphogenesis. (C) The first section was analysed for the presence of the truncated -catenin construct with an antibody to the HA epitope tag (green) while nuclei were counterstained with TOPRO3 (red). 2J). 3F) and/or had abnormal growths on the filaments themselves (Fig. 1997). The Resident shall not be entitled to make any objection or claim . TCF-1 expression in the developing feather tract. In addition, many of the buds that formed in apparently normal positions in the tracts of the injected embryos were thicker than normal, had defects in polarity (Fig. Pflugers Arch 61:427449, Exner S (1896) Ueber die elektrischen Eigenschaften der Haare und Federn. Small patches of viral transcripts are first detected in the chick ectoderm at day 6 of incubation, several days after infection. Within each tract, a single row of buds is formed first and sequential rows of buds are added subsequently as the inductive signal propagates through the tract. [609] As the dimple descends, 1B). By day 9, ectopic expression of TCF-1 is observed (Fig. Wnt7a is expressed in the epidermal placodes and Wnt11 transcripts are localized to the dermis (Tanda et al., 1995; Chuong et al., 1996; Morgan et al., 1998; Noramly and Morgan, 1998). -catenin accumulates in the cytoplasm of the periderm but is not observed in the nucleus (arrow). Patterning of the dorsal and femoral tracts is largely complete by day 13 of incubation although additional development of the buds continues. PubMed Although other factors may activate the pathway (Papkoff and Aikawa, 1998), a member of the Wnt family is a strong candidate for this signal. 1B). CAS Experiments manipulating BMP activity in the skin suggest that in addition to the primary inductive signal from the dermis, a secondary inductive signal is generated in the nascent placode itself and contributes to the specification of this structure (Noramly and Morgan, 1998). Development have published a recent Editorial showcasing some of our most popular features, as well as introducing some new initiatives. Localized growth zones (LoGZ) are located at the tip of the feather during early development, but become . At this stage, -catenin staining is prominent at the ectodermal cell surface but is not observed in the cytoplasm or nucleus of cells in either layer (data not shown). Even in an early stage of feather bud formation when dermal condensates appear, the mesenchymal cells in the developing feather bud or interbud dermis are still plastic and can grow into either new dermal condensates or interbud dermal fibroblasts after they are dissociated and reconstituted with embryonic epidermis (Chuong et al. At this time, Delta-1 is expressed in a complementary fashion within the boundaries of the Notch-1 expression domain. Int J Dev Biol 48:181191, Zi J, Yu X, Li Y, Hu X, Xu C, Wang X, Liu X, Fu R (2003) Coloration strategies in peacock feathers. To characterize the effect of exogenous activated -catenin on endogenous gene expression, whole-mount in situ analysis was performed on a total of 123 embryos. In addition, ectopic follicles were induced by activation of the -catenin pathway in both cases. All rights reserved. Univ Calif Publ Zool 13:243446, Chatterjee S (1997) The rise of birds: 225 million years of evolution. 32. Bird flight and behavior Flashcards | Quizlet When the cells of the placode have adopted a columnar morphology, nuclear -catenin staining is bright in this region and absent in interfollicular ectoderm (Fig. Induced placodes are also capable of recruiting dermis in interfollicular skin. 5B), while others were curled (Fig. 7C-E). During the earlier steps of bud specification, we cannot distinguish whether the localization of -catenin signaling reflects local expression of activating ligands or restriction in responsiveness of cells to more broadly expressed ligands. To compare the extent of the expression of ectopic Shh with induced BMP-2 expression, sequential detections of BMP-2 and Shh were performed. Introduction to the Morphology, Development, and Ecology of Feathers. The border of Delta and Serrate gene expression is often abnormally oriented or curved in infected buds as well (data not shown). Expression of BMP-2 in the nascent placode could regulate formation of adjacent placodes by inhibiting the response to a broadly expressed inducer in surrounding cells. Indiana University Press, Bloomington, pp 234250, Hosker A (1936) Studies on the epidermal structures of birds. The two constructs employed to express stabilized -catenin are also not identical. The nuclear localization of -catenin throughout the dense dermis is transient and fades rapidly as development proceeds. One change in dermal cells that participate in the condensation which could promote the nuclear accumulation of -catenin is increased expression of TCF. This pattern persists through intermediate bud stages (Fig. These areas of ectopic Shh expression coincide with the presence of viral infection as evidenced by subsequent detection of viral transcripts (C). Birds with constitutively active aromatase activity convert androgen to estrogen in the skin and have female feathering . This construct is sufficient to induce bud formation since it does so both within presumptive feather tracts and in normally featherless regions where tract-specific signals are absent. Canadian Association for Conservation of Cultural Property, Ottawa, pp 127147, Lillie FR, Wang H (1941) Physiology of development of the feather. A day later in development, dense dermis formation has progressed through the tract and bud formation has begun in more medial regions. Dev Biol 106:406413, Harris MP, Fallon JF, Prum RO (2002) Shh-Bmp2 signaling module and the evolutionary origin and diversification of feathers. 1E,G). Pflugers Arch 63:305316, Feo TJ, Prum RO (2014) Theoretical morphology and development of flight feather vane asymmetry with experimental tests in parrots. The expression of the Notch receptors and their ligands Delta and Serrate are also early indicators of anterior-posterior patterning during bud development (Chen et al., 1997). The bars below this diagram indicate the binding domains for -catenin (blue), TCF (purple), cadherin (green) and APC (red). At this stage, development of the feather tracts has not yet begun. J R Soc Interface 9:22792289, CrossRef Find out more and apply to Developments 2023 Journal Meeting here.

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