Dynamic evolution of the alpha (α) and beta (β) keratins has accompanied integument diversification and the adaptation of birds into novel lifestyles.
Abstract
BACKGROUND: Vertebrate skin appendages are constructed of keratins produced by multigene
families. Alpha (α) keratins are found in all vertebrates, while beta (β) keratins
are found exclusively in reptiles and birds. We have studied the molecular evolution
of these gene families in the genomes of 48 phylogenetically diverse birds and their
expression in the scales and feathers of the chicken. RESULTS: We found that the total
number of α-keratins is lower in birds than mammals and non-avian reptiles, yet two
α-keratin genes (KRT42 and KRT75) have expanded in birds. The β-keratins, however,
demonstrate a dynamic evolution associated with avian lifestyle. The avian specific
feather β-keratins comprise a large majority of the total number of β-keratins, but
independently derived lineages of aquatic and predatory birds have smaller proportions
of feather β-keratin genes and larger proportions of keratinocyte β-keratin genes.
Additionally, birds of prey have a larger proportion of claw β-keratins. Analysis
of α- and β-keratin expression during development of chicken scales and feathers demonstrates
that while α-keratins are expressed in these tissues, the number and magnitude of
expressed β-keratin genes far exceeds that of α-keratins. CONCLUSIONS: These results
support the view that the number of α- and β-keratin genes expressed, the proportion
of the β-keratin subfamily genes expressed and the diversification of the β-keratin
genes have been important for the evolution of the feather and the adaptation of birds
into multiple ecological niches.
Type
Journal articleSubject
AnimalsAvian Proteins
Birds
Evolution, Molecular
Feathers
Humans
Keratins
Mammals
Multigene Family
Phylogeny
beta-Keratins
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https://hdl.handle.net/10161/9318Published Version (Please cite this version)
10.1186/s12862-014-0249-1Publication Info
Greenwold, Matthew J; Bao, Weier; Jarvis, Erich D; Hu, Haofu; Li, Cai; Gilbert, M
Thomas P; ... Sawyer, Roger H (2014). Dynamic evolution of the alpha (α) and beta (β) keratins has accompanied integument
diversification and the adaptation of birds into novel lifestyles. BMC Evol Biol, 14. pp. 249. 10.1186/s12862-014-0249-1. Retrieved from https://hdl.handle.net/10161/9318.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Erich David Jarvis
Adjunct Professor in the Deptartment of Neurobiology
Dr. Jarvis' laboratory studies the neurobiology of vocal communication. Emphasis is
placed on the molecular pathways involved in the perception and production of learned
vocalizations. They use an integrative approach that combines behavioral, anatomical,
electrophysiological and molecular biological techniques. The main animal model used
is songbirds, one of the few vertebrate groups that evolved the ability to learn vocalizations.
The generality of the discoveries is tested in other vocal lear

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