The Crest Phenotype in Chicken Is Associated with Ectopic Expression of HOXC8 in Cranial Skin

Variation in regional identity, patterning, and structure of epidermal appendages contributes to skin diversity among many vertebrate groups, and is perhaps most striking in birds. In pioneering work on epidermal appendage patterning, John Saunders and his contemporaries took advantage of epidermal appendage diversity within and among domestic chicken breeds to establish the importance of mesoderm-ectoderm signaling in determining skin patterning. Diversity in chickens and other domestic birds, including pigeons, is driving a new wave of research to dissect the molecular genetic basis of epidermal appendage patterning. Domestic birds are not only outstanding models for embryonic manipulations, as Saunders recognized, but they are also ideal genetic models for discovering the specific genes that control normal development and the mutations that contribute to skin diversity. Here, we review recent genetic and genomic approaches to uncover the basis of epidermal macropatterning, micropatterning, and structural variation. We also present new results that confirm expression changes in two limb identity genes in feather-footed pigeons, a case of variation in appendage structure and identity.

Section: Variation In Epidermal Appendage Structurementioning

confidence: 99%

Section: Variation In Epidermal Appendage Structurementioning

confidence: 99%

See 1 more Smart Citation

Genomic determinants of epidermal appendage patterning and structure in domestic birds

Boer

Hollebeke

Shapiro

2017

“…Developmentally, head crests in domestic pigeons originate as a reversal of feather placodes on the head and neck (Shapiro et al, 2013). Head crest development in domestic chickens, in contrast, comprises elongation of head feathers but not a change in the direction of growth, and is not associated with EPHB2 , but instead with ectopic expression of HOXC8 (Wang et al, 2012). …”

Section: The Molecular Basis Of Phenotypic Variation In Pigeonsmentioning

confidence: 99%

Pigeonetics takes flight: Evolution, development, and genetics of intraspecific variation

Domyan

Shapiro

2017

Intensive artificial selection over thousands of years has produced hundreds of varieties of domestic pigeon. As Charles Darwin observed, the morphological differences among breeds can rise to the magnitude of variation typically observed among different species. Nevertheless, different pigeon varieties are interfertile, thereby enabling forward genetic and genomic approaches to identify genes that underlie derived traits. Building on classical genetic studies of pigeon variation, recent molecular investigations find a spectrum of coding and regulatory alleles controlling derived traits, including plumage color, feather growth polarity, and limb identity. Developmental and genetic analyses of pigeons are revealing the molecular basis of variation in a classic example of extreme intraspecific diversity, and have the potential to nominate genes that control variation among other birds and vertebrates in general.

“…Mutants with craniofacial association in chick are typified by the talpid strains, two of which are now known to be ciliopathies (Buxton et al, 2004; Chang et al, 2014), as well as other mutants that are associated with feather patterning (e.g. crested) (Wang et al, 2012), and in quail by hereditary multiple malformation (Tsudzuki et al, 1998). Second, the natural variation of beak morphology in Darwin’s finches, coupled with the relatively rapid evolution of these species, provides a means to make predictions from the available genomic data with respect to the genetic control of beak shape and size that can then be tested by experimental manipulation (Abzhanov et al, 2006; Abzhanov et al, 2004; Lamichhaney et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

The old and new face of craniofacial research: How animal models inform human craniofacial genetic and clinical data

Otterloo

Williams

Artinger

2016

The craniofacial skeletal structures that comprise the human head develop from multiple tissues that converge to form the bones and cartilage of the face. Because of their complex development and morphogenesis, many human birth defects arise due to disruptions in these cellular populations. Thus, determining how these structures normally develop is vital if we are to gain a deeper understanding of craniofacial birth defects and devise treatment and prevention options. In this review, we will focus on how animal model systems have been used historically and in an ongoing context to enhance our understanding of human craniofacial development. We do this by first highlighting “animal to man” approaches: that is, how animal models are being utilized to understand fundamental mechanisms of craniofacial development. We discuss emerging technologies, including high throughput sequencing and genome editing, and new animal repository resources, and how their application can revolutionize the future of animal models in craniofacial research. Secondly, we highlight “man to animal” approaches, including the current use of animal models to test the function of candidate human disease variants. Specifically, we outline a common workflow deployed after discovery of a potentially disease causing variant based on a select set of recent examples in which human mutations are investigated in vivo using animal models. Collectively, these topics will provide a pipeline for the use of animal models in understanding human craniofacial development and disease for clinical geneticist and basic researchers alike.