Sonic hedgehog specifies flight feather positional information in avian wings

Busby, Lara; Aceituno, Cristina; McQueen, Caitlin; Rich, Constance A; Ros, María A.; Towers, Matthew

doi:10.1242/dev.188821

Cited by 14 publications

(13 citation statements)

References 38 publications

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“…Molecular pathways involved in feather induction and morphogenesis have been extensively investigated in the past 20 years 4,8 . But little is known about how skin regional differences across‐the body are specified and how the formation of different types of feathers are controlled 9‐11 . This issue can be analyzed from the perspective of dermal control or epidermal differentiation 7,12 …”

Section: Introductionmentioning

confidence: 99%

Regional specific differentiation of integumentary organs: SATB2 is involved in α‐ and β‐keratin gene cluster switching in the chicken

Lin

Liang

et al. 2021

Developmental Dynamics

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Background: Animals develop skin regional specificities to best adapt to their environments. Birds are excellent models in which to study the epigenetic mechanisms that facilitate these adaptions. Patients suffering from SATB2 mutations exhibit multiple defects including ectodermal dysplasia-like changes. The preferential expression of SATB2, a chromatin regulator, in feather-forming compared to scale-forming regions, suggests it functions in regional specification of chicken skin appendages by acting on either differentiation or morphogenesis.Results: Retrovirus mediated SATB2 misexpression in developing feathers, beaks, and claws causes epidermal differentiation abnormalities (e.g. knobs, plaques) with few organ morphology alterations. Chicken β-keratins are encoded in 5 sub-clusters (Claw, Feather, Feather-like, Scale, and Keratinocyte) on Chromosome 25 and a large Feather keratin cluster on Chromosome 27.Type I and II α-keratin clusters are located on Chromosomes 27 and 33, respectively. Transcriptome analyses showed these keratins (1) are often tuned up or down collectively as a sub-cluster, and (2) these changes occur in a temporospatial specific manner.Conclusions: These results suggest an organizing role of SATB2 in clusterlevel gene co-regulation during skin regional specification.

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Section: Introductionmentioning

confidence: 99%

Regional specific differentiation of integumentary organs: SATB2 is involved in α‐ and β‐keratin gene cluster switching in the chicken

Lin

Liang

et al. 2021

Developmental Dynamics

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“…Furthermore, it should be taken into consideration that different types of regulatory innovations and their distinct co‐option mechanism can inform about the phylogenetic history of a structure (Tarchini & Duboule, 2006). For example, the Shh signalling pathway also contributes to positional information in the formation of adult flight feathers, involving the co‐option of a pre‐existing digit patterning mechanism (Busby et al, 2020). In the Emu's forelimb, a cardiac transcription factor ( NKX2.5 ) plays a role in outgrowth and wing patterning by inhibiting early limb bud expansion and subsequent muscle growth (Farlie et al, 2017; Newton & Smith, 2021).…”

Section: Discussionmentioning

confidence: 99%

The forelimbs of Alvarezsauroidea (Dinosauria: Theropoda): Insight from evolutionary teratology

Guinard¹

2022

Journal of Morphology

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Alvarezsauroidea (Tetanurae) are nonavian theropod dinosaurs whose forelimb evolution is characterised by the overdevelopment of digit I, at the expense of the other two digits, complemented by a drastic forelimb shortening in derived species (Parvicursorinae). These variations are recognised as evolutionary developmental anomalies. Evolutionary teratology hence leads to a double diagnosis with (1) macrodactyly of digit I and microdactyly of digits II and III, plus (2) anterior micromelia. The teratological macrodactyly/microdactyly coupling evolved first.Developmental mechanisms disturbing limb proportion are thought to be convergent with those of other Tetanurae (Tyrannosauridae, Carcharodontosauridae). As for the manual anomalies, both are specific to Alvarezsauroidea (macrodactyly/ microdactyly) and inherited (digit loss/reduction). While considering the frame-shift theory, posterior digits develop before the most anterior ones. There would therefore be a decrease in the area devoted to digits II (condensation 3) and III (condensation 4), in connection with the Shh signalling pathway, interacting with other molecular players such as the GLI3 protein and the Hox system. Developmental independence of digit I (condensation 2) would contribute to generating a particular morphology. Macrodactyly would be linked to a variation in Hoxd-13, impacting Gli3 activity, and increasing cell proliferation. The loss/reduction of digital ray/phalanges (digits II and III), would be associated with Shh activity, a mechanism inherited from the theropodan ancestry. The macrodactyly/microdactyly coupling, and then anterior micromelia, fundamentally changed the forelimb mechanical function, compared to the 'classical' grasping structure of basal representatives and other theropods. The distal ossification of the macrodactylian digit has been identified as physiological, implying the use of the structure. However, the debate on a particular 'adaptive' use is pointless as the ecology of an organism is interactively complex, being both at the scale of the individual and dependent on circumstances. Other anatomical features also allow for compensation and different predation (cursorial hindlimbs).

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“…Here we use GWAS to identify significant associations between genetic variation and the molt-migratory phenotype and find the strongest association with a SNP located within an intronic region on the GLI2 gene. GLI2 is a clear candidate for involvement in feather molt, as studies have shown it is a transcription regulator of the Sonic Hedgehog (Shh) signaling pathway that specifies positional information required for the formation of adult flight feathers 84 . Moreover, GLI2 activates and is co-expressed with Follistatin 85 , a gene that is linked to the development of hair follicles in mammals and feathers in birds as demonstrated by gene knockout experiments in Mus musculus 86 and ectopic induction of feather growth in Gallus gallus 87,88 .…”

Section: Discussionmentioning

confidence: 99%

Genetic and ecological drivers of molt in a migratory bird

Contina

Bossu

Allen

et al. 2022

Preprint

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The ability of animals to sync the timing and location of molting (the replacement of hair, skin, exoskeletons or feathers) with peaks in resource availability has important implications for their ecology and evolution. In migratory birds, the timing and location of pre-migratory feather molting, a period when feathers are shed and replaced with newer, more aerodynamic feathers, can vary within and between species. While hypotheses to explain the evolution of intraspecific variation in the timing and location of molt have been proposed, little is known about the genetic basis of this trait or the specific environmental drivers that may result in natural selection for distinct molting phenotypes. Here we take advantage of intraspecific variation in the timing and location of molt in the iconic songbird, the Painted Bunting (Passerina ciris) to investigate the genetic and ecological drivers of distinct molting phenotypes. Specifically, we use genome-wide genetic sequencing in combination with stable isotope analysis to determine population genetic structure and molting phenotype across thirteen breeding sites. We then use genome-wide association analysis (GWAS) to identify a suite of genes associated with molting and pair this with gene-environment association analysis (GEA) to investigate potential environmental drivers of genetic variation in this trait. Associations between genetic variation in molt-linked genes and the environment are further tested via targeted SNP genotyping in 25 additional breeding populations across the range. Together, our integrative analysis suggests that molting is in part regulated by genes linked to feather development and structure (GLI2 and CSPG4) and that genetic variation in these genes is associated with seasonal variation in precipitation and aridity. Overall, this work provides important insights into the genetic basis and potential selective forces behind phenotypic variation in what is arguably one of the most important fitness-linked traits in a migratory bird.

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Sonic hedgehog specifies flight feather positional information in avian wings

Cited by 14 publications

References 38 publications

Regional specific differentiation of integumentary organs: SATB2 is involved in α‐ and β‐keratin gene cluster switching in the chicken

Regional specific differentiation of integumentary organs: SATB2 is involved in α‐ and β‐keratin gene cluster switching in the chicken

The forelimbs of Alvarezsauroidea (Dinosauria: Theropoda): Insight from evolutionary teratology

Genetic and ecological drivers of molt in a migratory bird

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