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Alibardi L, Eckhart L. Immunolocalization of epidermal differentiation complex proteins reveals distinct molecular compositions of cells that control structure and mechanical properties of avian skin appendages. J Morphol 2021; 282:917-933. [PMID: 33830534 DOI: 10.1002/jmor.21357] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 04/02/2021] [Accepted: 04/07/2021] [Indexed: 11/09/2022]
Abstract
The epidermal differentiation complex (EDC) is a cluster of genes that encode structural proteins of skin derivatives with variable mechanical performances, from the scales of reptiles and birds to the hard claws and beaks, and to the flexible but resistant corneous material of feathers. Corneous proteins with or without extended beta-regions are produced from avian genomes, and include the largely prevalent corneous beta proteins (CβPs, formerly indicated as beta-keratins), and minor contribution from histidine-rich proteins, trichohyalin-like proteins (scaffoldin), loricrin, and other proteins rich in cysteine or other types of amino acids. The light-microscopic and ultrastructural immunolocalization of major and minor EDC-proteins in avian skin (feather CβPs, EDKM, EDWM, EDMTFH, EDDM, and scaffoldin) suggests that each specific appendage consists of a particular mix of these proteins in addition to the main proteins containing a peculiar beta-region of 34 amino acids, indicated as feather/scale/claw/beak CβPs (fCβPs, sCβPs, cCβPs, bCβPs). This indicates that numerous proteins of the EDC are added to the variable meshwork of intermediate filament keratins to produce avian epidermis with different mechanical and functional properties. Although the specific roles for these proteins are not known they likely make an important contribution to the final material properties of the different skin appendages of birds. The highest number of sauropsid CβPs is found in birds, suggesting a relation to the evolution of feathers, and additional epidermal differentiation proteins have contributed to the evolutionary adaptations of avian skin.
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Affiliation(s)
- Lorenzo Alibardi
- Comparative Histolab Padova and Department of Biology, University of Bologna, Bologna, Italy
| | - Leopold Eckhart
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
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Immunohistochemical detection of sulfhydryl oxidase in chick skin appendages and feathers suggests that the enzyme contributes to maturation of the corneous material. ZOOMORPHOLOGY 2020. [DOI: 10.1007/s00435-020-00498-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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3
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Holthaus KB, Eckhart L, Dalla Valle L, Alibardi L. Review: Evolution and diversification of corneous beta‐proteins, the characteristic epidermal proteins of reptiles and birds. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2019; 330:438-453. [DOI: 10.1002/jez.b.22840] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 11/28/2018] [Accepted: 12/23/2018] [Indexed: 02/04/2023]
Affiliation(s)
- Karin Brigit Holthaus
- Department of DermatologyMedical University of ViennaWien Austria
- Dipartimento di Scienze Biologiche, Geologiche ed Ambientali (BiGeA)University of BolognaBologna Italy
| | - Leopold Eckhart
- Department of DermatologyMedical University of ViennaWien Austria
| | | | - Lorenzo Alibardi
- Dipartimento di Scienze Biologiche, Geologiche ed Ambientali (BiGeA)University of BolognaBologna Italy
- Comparative Histolab PadovaPadova Italy
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Alibardi L. Review: mapping epidermal beta-protein distribution in the lizard Anolis carolinensis shows a specific localization for the formation of scales, pads, and claws. PROTOPLASMA 2016; 253:1405-1420. [PMID: 26597267 DOI: 10.1007/s00709-015-0909-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 11/09/2015] [Indexed: 06/05/2023]
Abstract
The epidermis of lizards is made of multiple alpha- and beta-layers with different characteristics comprising alpha-keratins and corneous beta-proteins (formerly beta-keratins). Three main modifications of body scales are present in the lizard Anolis carolinensis: gular scales, adhesive pad lamellae, and claws. The 40 corneous beta-proteins present in this specie comprise glycine-rich and glycine-cysteine-rich subfamilies, while the 41 alpha-keratins comprise cysteine-poor and cysteine-rich subfamilies, the latter showing homology to hair keratins. Other genes for corneous proteins are present in the epidermal differentiation complex, the locus where corneous protein genes are located. The review summarizes the main sites of immunolocalization of beta-proteins in different scales and their derivatives producing a unique map of body distribution for these structural proteins. Small glycine-rich beta-proteins participate in the formation of the mechanically resistant beta-layer of most scales. Small glycine-cysteine beta-proteins have a more varied localization in different scales and are also present in the pliable alpha-layer. In claws, cysteine-rich alpha-keratins prevail over cysteine-poor alpha-keratins and mix to glycine-cysteine-rich beta-proteins. The larger beta-proteins with a molecular mass similar to that of alpha-keratins participate in the formation of the fibrous meshwork present in differentiating beta-cells and likely interact with alpha-keratins. The diverse localization of alpha-keratins, beta-proteins, and other proteins of the epidermal differentiation complex gives rise to variably pliable, elastic, or hard corneous layers in different body scales. The corneous layers formed in the softer or harder scales, in the elastic pad lamellae, or in the resistant claws possess peculiar properties depending on the ratio of specific corneous proteins.
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Affiliation(s)
- Lorenzo Alibardi
- Comparative Histolab and Department of Biology, Geology and Environmental Sciences, University of Bologna, via Selmi 3, 40126, Bologna, Italy.
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ALIBARDI LORENZO. Sauropsids Cornification is Based on Corneous Beta-Proteins, a Special Type of Keratin-Associated Corneous Proteins of the Epidermis. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2016; 326:338-351. [DOI: 10.1002/jez.b.22689] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Revised: 06/22/2016] [Accepted: 07/05/2016] [Indexed: 12/13/2022]
Affiliation(s)
- LORENZO ALIBARDI
- Comparative Histolab and Department of Bigea; University of Bologna; Italy
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Calvaresi M, Eckhart L, Alibardi L. The molecular organization of the beta-sheet region in Corneous beta-proteins (beta-keratins) of sauropsids explains its stability and polymerization into filaments. J Struct Biol 2016; 194:282-91. [DOI: 10.1016/j.jsb.2016.03.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 02/29/2016] [Accepted: 03/05/2016] [Indexed: 11/17/2022]
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Alibardi L. The Process of Cornification Evolved From the Initial Keratinization in the Epidermis and Epidermal Derivatives of Vertebrates: A New Synthesis and the Case of Sauropsids. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 327:263-319. [DOI: 10.1016/bs.ircmb.2016.06.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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8
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Alibardi L. Immunolocalization of large corneous beta-proteins in the green anole lizard (Anolis carolinensis) suggests that they form filaments that associate to the smaller beta-proteins in the beta-layer of the epidermis. J Morphol 2015. [DOI: 10.1002/jmor.20415] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Lorenzo Alibardi
- Comparative Histolab and Department of Bigea; University of Bologna; Bologna Italy
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Immunoreactivity to the pre-core box antibody shows that most glycine-rich beta-proteins accumulate in lepidosaurian beta-layer and in the corneous layer of crocodilian and turtle epidermis. Micron 2014; 57:31-40. [DOI: 10.1016/j.micron.2013.10.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 10/04/2013] [Accepted: 10/04/2013] [Indexed: 11/18/2022]
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Ultrastructural immunocytochemistry for the central region of keratin associated-beta-proteins (beta-keratins) shows the epitope is constantly expressed in reptilian epidermis. Tissue Cell 2013; 45:241-52. [DOI: 10.1016/j.tice.2013.01.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 01/22/2013] [Accepted: 01/28/2013] [Indexed: 11/21/2022]
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Clark CJ, Elias DO, Prum RO. Hummingbird feather sounds are produced by aeroelastic flutter, not vortex-induced vibration. ACTA ACUST UNITED AC 2013; 216:3395-403. [PMID: 23737562 DOI: 10.1242/jeb.080317] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Males in the 'bee' hummingbird clade produce distinctive, species-specific sounds with fluttering tail feathers during courtship displays. Flutter may be the result of vortex shedding or aeroelastic interactions. We investigated the underlying mechanics of flutter and sound production of a series of different feathers in a wind tunnel. All feathers tested were capable of fluttering at frequencies varying from 0.3 to 10 kHz. At low airspeeds (Uair) feather flutter was highly damped, but at a threshold airspeed (U*) the feathers abruptly entered a limit-cycle vibration and produced sound. Loudness increased with airspeed in most but not all feathers. Reduced frequency of flutter varied by an order of magnitude, and declined with increasing Uair in all feathers. This, along with the presence of strong harmonics, multiple modes of flutter and several other non-linear effects indicates that flutter is not simply a vortex-induced vibration, and that the accompanying sounds are not vortex whistles. Flutter is instead aeroelastic, in which structural (inertial/elastic) properties of the feather interact variably with aerodynamic forces, producing diverse acoustic results.
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Affiliation(s)
- Christopher J Clark
- Peabody Museum of Natural History, Yale University, PO Box 208106, New Haven, CT 06511, USA.
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Alibardi L. Immunolocalization of alpha-keratins and feather beta-proteins in feather cells and comparison with the general process of cornification in the skin of mammals. Ann Anat 2013; 195:189-98. [DOI: 10.1016/j.aanat.2012.08.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 07/31/2012] [Accepted: 08/14/2012] [Indexed: 10/27/2022]
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Alibardi L. Comparative immunolocalization of keratin-associated beta-proteins (beta-keratins) supports a new explanation for the cyclical process of keratinocyte differentiation in lizard epidermis. ACTA ZOOL-STOCKHOLM 2012. [DOI: 10.1111/azo.12003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Lorenzo Alibardi
- Comparative Histolab and Department of Biology University of Bologna Bologna Italy
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Alibardi L. Cornification in reptilian epidermis occurs through the deposition of keratin-associated beta-proteins (beta-keratins) onto a scaffold of intermediate filament keratins. J Morphol 2012; 274:175-93. [DOI: 10.1002/jmor.20086] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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15
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ALIBARDI L, SEGALLA A, DALLA VALLE L. Distribution of Specific Keratin-Associated Beta-Proteins (Beta-Keratins) in the Epidermis of the Lizard Anolis carolinensis Helps to Clarify the Process of Cornification in Lepidosaurians. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2012; 318:388-403. [DOI: 10.1002/jez.b.22454] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- L. ALIBARDI
- Comparative Histolab and Department of Biology; University of Bologna; Bologna; Italy
| | - A. SEGALLA
- Department of Biology; University of Padova; Padova; Italy
| | - L. DALLA VALLE
- Department of Biology; University of Padova; Padova; Italy
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Maia R, Macedo RHF, Shawkey MD. Nanostructural self-assembly of iridescent feather barbules through depletion attraction of melanosomes during keratinization. J R Soc Interface 2011; 9:734-43. [PMID: 21865251 DOI: 10.1098/rsif.2011.0456] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Avian plumage colours are model traits in understanding the evolution of sexually selected ornamental traits. Paradoxically, iridescent structural colours, probably the most dazzling of these traits, remain the most poorly understood. Though some data suggest that expression of bright iridescent plumage colours produced by highly ordered arrays of melanosomes and keratin is condition-dependent, almost nothing is known of their ontogeny and thus of any developmental mechanisms that may be susceptible to perturbation. Here, we use light and electron microscopy to compare the ontogeny of iridescent male and non-iridescent female feathers in blue-black grassquits. Feather barbules of males contain a single layer of melanosomes bounded by a thin layer of keratin-producing blue iridescent colour, while those of females contain disorganized melanosomes and no outer layer. We found that nanostructural organization of male barbules occurs late in development, following death of the barbule cell, and is thus unlikely to be under direct cellular control, contrary to previous suggestions. Rather, organization appears to be caused by entropically driven self-assembly through depletion attraction forces that pin melanosomes to the edge of barbule cells and to one another. These forces are probably stronger in developing barbules of males than of females because their melanosomes are (i) larger, (ii) more densely packed, and (iii) more homogeneously distributed owing to the more consistent shape of barbules during keratinization. These data provide the first proposed developmental pathway for iridescent plumage colours, and suggest that any condition dependence of iridescent barbules is likely driven by factors other than direct metabolic cost.
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Affiliation(s)
- Rafael Maia
- Department of Biology, Integrated Bioscience Program, University of Akron, Akron, OH 44325-3908, USA.
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Peters A, Kurvers RHJM, Roberts ML, Delhey K. No evidence for general condition-dependence of structural plumage colour in blue tits: an experiment. J Evol Biol 2011; 24:976-87. [PMID: 21306464 DOI: 10.1111/j.1420-9101.2011.02229.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Condition-dependence is a central but contentious tenet of evolutionary theories on the maintenance of ornamental traits, and this is particularly true for structural plumage colour. By providing diets of different nutritional quality to moulting male and female blue tits, we experimentally manipulated general condition within the natural range, avoiding deprivation or stressful treatments. We measured reflectance of the structural-coloured UV/blue crown, a sexually selected trait in males, and the white cheek, a nonpigmented structural colour, directly after moult and again during the following spring mating season. We employed a variety of colour indices, based on spectral shape and avian visual models but, despite significant variation in condition and coloration, found no evidence for condition-dependence of UV/blue or white plumage colour during either season. These and previously published results suggest that structural colour might be sensitive to stress, rather than reduced body condition, during moult.
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Affiliation(s)
- A Peters
- Sexual Signals Group, Max Planck Institute for Ornithology, Vogelwarte Radolfzell, Radolfzell, Germany.
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Noh H, Liew SF, Saranathan V, Prum RO, Mochrie SGJ, Dufresne ER, Cao H. Contribution of double scattering to structural coloration in quasiordered nanostructures of bird feathers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:051923. [PMID: 20866277 DOI: 10.1103/physreve.81.051923] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Revised: 04/02/2010] [Indexed: 05/29/2023]
Abstract
We measured the polarization- and angle-resolved optical scattering and reflection spectra of the quasiordered nanostructures in the bird feather barbs. In addition to the primary peak that originates from single scattering, we observed a secondary peak which exhibits depolarization and distinct angular dispersion. We explained the secondary peak in terms of double scattering, i.e., light is scattered successively twice by the structure. The two sequential single-scattering events are considered uncorrelated. Using the Fourier power spectra of the nanostructures obtained from the small-angle x-ray scattering experiment, we calculated the double scattering of light in various directions. The double-scattering spectrum is broader than the single-scattering spectrum, and it splits into two subpeaks at larger scattering angle. The good agreement between the simulation results and the experimental data confirms that double scattering of light makes a significant contribution to the structural color.
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Affiliation(s)
- Heeso Noh
- Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA
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Alibardi L, Dalla Valle L, Nardi A, Toni M. Evolution of hard proteins in the sauropsid integument in relation to the cornification of skin derivatives in amniotes. J Anat 2010; 214:560-86. [PMID: 19422429 DOI: 10.1111/j.1469-7580.2009.01045.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Hard skin appendages in amniotes comprise scales, feathers and hairs. The cell organization of these appendages probably derived from the localization of specialized areas of dermal-epidermal interaction in the integument. The horny scales and the other derivatives were formed from large areas of dermal-epidermal interaction. The evolution of these skin appendages was characterized by the production of specific coiled-coil keratins and associated proteins in the inter-filament matrix. Unlike mammalian keratin-associated proteins, those of sauropsids contain a double beta-folded sequence of about 20 amino acids, known as the core-box. The core-box shows 60%-95% sequence identity with known reptilian and avian proteins. The core-box determines the polymerization of these proteins into filaments indicated as beta-keratin filaments. The nucleotide and derived amino acid sequences for these sauropsid keratin-associated proteins are presented in conjunction with a hypothesis about their evolution in reptiles-birds compared to mammalian keratin-associated proteins. It is suggested that genes coding for ancestral glycine-serine-rich sequences of alpha-keratins produced a new class of small matrix proteins. In sauropsids, matrix proteins may have originated after mutation and enrichment in proline, probably in a central region of the ancestral protein. This mutation gave rise to the core-box, and other regions of the original protein evolved differently in the various reptilians orders. In lepidosaurians, two main groups, the high glycine proline and the high cysteine proline proteins, were formed. In archosaurians and chelonians two main groups later diversified into the high glycine proline tyrosine, non-feather proteins, and into the glycine-tyrosine-poor group of feather proteins, which evolved in birds. The latter proteins were particularly suited for making the elongated barb/barbule cells of feathers. In therapsids-mammals, mutations of the ancestral proteins formed the high glycine-tyrosine or the high cysteine proteins but no core-box was produced in the matrix proteins of the hard corneous material of mammalian derivatives.
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Affiliation(s)
- Lorenzo Alibardi
- Dipartimento di Biologia evoluzionistica sperimentale, University of Bologna, Italy.
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Dalla Valle L, Nardi A, Bonazza G, Zuccal C, Emera D, Alibardi L. Forty keratin-associated β-proteins (β-keratins) form the hard layers of scales, claws, and adhesive pads in the green anole lizard, Anolis carolinensis. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2010; 314:11-32. [DOI: 10.1002/jez.b.21306] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Dalla Valle L, Nardi A, Alibardi L. Isolation of a new class of cysteine-glycine-proline-rich beta-proteins (beta-keratins) and their expression in snake epidermis. J Anat 2010; 216:356-67. [PMID: 20070430 DOI: 10.1111/j.1469-7580.2009.01192.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Scales of snakes contain hard proteins (beta-keratins), now referred to as keratin-associated beta-proteins. In the present study we report the isolation, sequencing, and expression of a new group of these proteins from snake epidermis, designated cysteine-glycine-proline-rich proteins. One deduced protein from expressed mRNAs contains 128 amino acids (12.5 kDa) with a theoretical pI at 7.95, containing 10.2% cysteine and 15.6% glycine. The sequences of two more snake cysteine-proline-rich proteins have been identified from genomic DNA. In situ hybridization shows that the messengers for these proteins are present in the suprabasal and early differentiating beta-cells of the renewing scale epidermis. The present study shows that snake scales, as previously seen in scales of lizards, contain cysteine-rich beta-proteins in addition to glycine-rich beta-proteins. These keratin-associated beta-proteins mix with intermediate filament keratins (alpha-keratins) to produce the resistant corneous layer of snake scales. The specific proportion of these two subfamilies of proteins in different scales can determine various degrees of hardness in scales.
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Dalla Valle L, Nardi A, Toni M, Emera D, Alibardi L. Beta-keratins of turtle shell are glycine-proline-tyrosine rich proteins similar to those of crocodilians and birds. J Anat 2009; 214:284-300. [PMID: 19207990 DOI: 10.1111/j.1469-7580.2008.01030.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
This study presents, for the first time, sequences of five beta-keratin cDNAs from turtle epidermis obtained by means of 5'- and 3'-rapid amplification of cDNA ends (RACE) analyses. The deduced amino acid sequences correspond to distinct glycine-proline-serine-tyrosine rich proteins containing 122-174 amino acids. In situ hybridization shows that beta-keratin mRNAs are expressed in cells of the differentiating beta-layers of the shell scutes. Southern blotting analysis reveals that turtle beta-keratins belong to a well-conserved multigene family. This result was confirmed by the amplification and sequencing of 13 genomic fragments corresponding to beta-keratin genes. Like snake, crocodile and avian beta-keratin genes, turtle beta-keratins contain an intron that interrupts the 5'-untranslated region. The length of the intron is variable, ranging from 0.35 to 1.00 kb. One of the sequences obtained from genomic amplifications corresponds to one of the five sequences obtained from cDNA cloning; thus, sequences of a total of 17 turtle beta-keratins were determined in the present study. The predicted molecular weight of the 17 different deduced proteins range from 11.9 to 17.0 kDa with a predicted isoelectric point of 6.8-8.4; therefore, they are neutral to basic proteins. A central region rich in proline and with beta-strand conformation shows high conservation with other reptilian and avian beta-keratins, and it is likely involved in their polymerization. Glycine repeat regions, often containing tyrosine, are localized toward the C-terminus. Phylogenetic analysis shows that turtle beta-keratins are more similar to crocodilian and avian beta-keratins than to those of lizards and snakes.
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Prum RO, Dufresne ER, Quinn T, Waters K. Development of colour-producing beta-keratin nanostructures in avian feather barbs. J R Soc Interface 2009; 6 Suppl 2:S253-65. [PMID: 19336345 DOI: 10.1098/rsif.2008.0466.focus] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The non-iridescent structural colours of avian feather barbs are produced by coherent light scattering from amorphous (i.e. quasi-ordered) nanostructures of beta-keratin and air in the medullary cells of feather barb rami. Known barb nanostructures belong to two distinct morphological classes. 'Channel' nanostructures consist of beta-keratin bars and air channels of elongate, tortuous and twisting forms. 'Spherical' nanostructures consist of highly spherical air cavities that are surrounded by thin beta-keratin bars and sometimes interconnected by tiny passages. Using transmission electron microscopy, we observe that the colour-producing channel-type nanostructures of medullary beta-keratin in feathers of the blue-and-yellow macaw (Ara ararauna, Psittacidae) develop by intracellular self-assembly; the process proceeds in the absence of any biological prepattern created by the cell membrane, endoplasmic reticulum or cellular intermediate filaments. We examine the hypothesis that the shape and size of these self-assembled, intracellular nanostructures are determined by phase separation of beta-keratin protein from the cytoplasm of the cell. The shapes of a broad sample of colour-producing channel-type nanostructures from nine avian species are very similar to those self-assembled during the phase separation of an unstable mixture, a process called spinodal decomposition (SD). In contrast, the shapes of a sample of spherical-type nanostructures from feather barbs of six species show a poor match to SD. However, spherical nanostructures show a strong morphological similarity to morphologies produced by phase separation of a metastable mixture, called nucleation and growth. We propose that colour-producing, intracellular, spongy medullary beta-keratin nanostructures develop their characteristic sizes and shapes by phase separation during protein polymerization. We discuss the possible role of capillary flow through drying of medullary cells in the development of the hollow morphology of typical and spongy feather medullary cells.
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Affiliation(s)
- Richard O Prum
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06511, USA.
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Hallahan DL, Keiper-Hrynko NM, Shang TQ, Ganzke TS, Toni M, Dalla Valle L, Alibardi L. Analysis of gene expression in gecko digital adhesive pads indicates significant production of cysteine- and glycine-rich beta-keratins. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2009; 312:58-73. [DOI: 10.1002/jez.b.21242] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Alibardi L, Toni M. Cytochemical and molecular characteristics of the process of cornification during feather morphogenesis. ACTA ACUST UNITED AC 2008; 43:1-69. [DOI: 10.1016/j.proghi.2008.01.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2008] [Accepted: 01/21/2008] [Indexed: 10/22/2022]
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Peters A, Delhey K, Johnsen A, Kempenaers B. The Condition‐Dependent Development of Carotenoid‐Based and Structural Plumage in Nestling Blue Tits: Males and Females Differ. Am Nat 2007. [DOI: 10.1086/510139] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Schrooyen PM, Dijkstra PJ, Oberthür RC, Bantjes A, Feijen J. Partially carboxymethylated feather keratins. 2. Thermal and mechanical properties of films. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2001; 49:221-230. [PMID: 11170581 DOI: 10.1021/jf0004154] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Free cysteine thiol groups of keratin extracted from chicken feathers were partially carboxymethylated with iodoacetic acid (25-76% cysteine modification). Stable dispersions were used for the preparation of films by solution casting. Glycerol was used as a plasticizer (0.05-0.47 g/g of keratin), and films were stored at a constant relative humidity (20, 30, 50, 70, or 90%). The degree of crystallinity in the films was higher when more cysteine residues were carboxymethylated. The films displayed an optimum in mechanical properties at approximately 50% cysteine carboxymethylation. The tensile strength at this optimum was 25 MPa, the E modulus, 350 MPa, and the elongation at break, 50%. Probably, this optimum was the result of both a decreasing amount of disulfide bonds and an increasing degree of crystallinity for higher degrees of cysteine modification. The influences of a higher amount of glycerol and of different storage conditions on the mechanical properties of films from keratin with a defined degree of cysteine modification were also investigated.
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Affiliation(s)
- P M Schrooyen
- Department of Chemical Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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Functional-morphological and biochemical correlations of the keratinized structures in the African Grey Parrot, Psittacus erithacus (Aves). ZOOMORPHOLOGY 1986. [DOI: 10.1007/bf00312112] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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CHENG K, BRUSH A. Feather Morphology of Four Different Mutations in the Japanese Quail. Poult Sci 1984. [DOI: 10.3382/ps.0630391] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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