1
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Corthésy N, Saleh F, Thomas C, Antcliffe JB, Daley AC. The effects of clays on bacterial community composition during arthropod decay. SWISS JOURNAL OF PALAEONTOLOGY 2024; 143:26. [PMID: 39006952 PMCID: PMC11236854 DOI: 10.1186/s13358-024-00324-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 06/18/2024] [Indexed: 07/16/2024]
Abstract
Fossilization, or the transition of an organism from the biosphere to the geosphere, is a complex mechanism involving numerous biological and geological variables. Bacteria are one of the most significant biotic players to decompose organic matter in natural environments, early on during fossilization. However, bacterial processes are difficult to characterize as many different abiotic conditions can influence bacterial efficiency in degrading tissues. One potentially important variable is the composition and nature of the sediment on which a carcass is deposited after death. We experimentally examined this by decaying the marine shrimp Palaemon varians underwater on three different clay sediments. Samples were then analyzed using 16S ribosomal RNA sequencing to identify the bacterial communities associated with each clay system. Results show that samples decaying on the surface of kaolinite have a lower bacterial diversity than those decaying on the surface of bentonite and montmorillonite, which could explain the limited decay of carcasses deposited on this clay. However, this is not the only role played by kaolinite, as a greater proportion of gram-negative over gram-positive bacteria is observed in this system. Gram-positive bacteria are generally thought to be more efficient at recycling complex polysaccharides such as those forming the body walls of arthropods. This is the first experimental evidence of sediments shaping an entire bacterial community. Such interaction between sediments and bacteria might have contributed to arthropods' exquisite preservation and prevalence in kaolinite-rich Lagerstätten of the Cambrian Explosion. Supplementary Information The online version contains supplementary material available at 10.1186/s13358-024-00324-7.
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Affiliation(s)
- Nora Corthésy
- Institute of Earth Sciences, University of Lausanne, Géopolis, 1015 Lausanne, Switzerland
| | - Farid Saleh
- Institute of Earth Sciences, University of Lausanne, Géopolis, 1015 Lausanne, Switzerland
| | - Camille Thomas
- Institute of Geological Sciences, Oeschger Centre for Climate Research, University of Bern, Baltzerstrasse 1+3, 3012 Bern, Switzerland
- Department of Earth Sciences, University of Geneva, rue des Maraichers 13, 1205 Geneva, Switzerland
| | - Jonathan B Antcliffe
- Institute of Earth Sciences, University of Lausanne, Géopolis, 1015 Lausanne, Switzerland
| | - Allison C Daley
- Institute of Earth Sciences, University of Lausanne, Géopolis, 1015 Lausanne, Switzerland
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2
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Yang Z, Jiang B, Xu J, McNamara ME. Cellular structure of dinosaur scales reveals retention of reptile-type skin during the evolutionary transition to feathers. Nat Commun 2024; 15:4063. [PMID: 38773066 PMCID: PMC11109146 DOI: 10.1038/s41467-024-48400-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 04/30/2024] [Indexed: 05/23/2024] Open
Abstract
Fossil feathers have transformed our understanding of integumentary evolution in vertebrates. The evolution of feathers is associated with novel skin ultrastructures, but the fossil record of these changes is poor and thus the critical transition from scaled to feathered skin is poorly understood. Here we shed light on this issue using preserved skin in the non-avian feathered dinosaur Psittacosaurus. Skin in the non-feathered, scaled torso is three-dimensionally replicated in silica and preserves epidermal layers, corneocytes and melanosomes. The morphology of the preserved stratum corneum is consistent with an original composition rich in corneous beta proteins, rather than (alpha-) keratins as in the feathered skin of birds. The stratum corneum is relatively thin in the ventral torso compared to extant quadrupedal reptiles, reflecting a reduced demand for mechanical protection in an elevated bipedal stance. The distribution of the melanosomes in the fossil skin is consistent with melanin-based colouration in extant crocodilians. Collectively, the fossil evidence supports partitioning of skin development in Psittacosaurus: a reptile-type condition in non-feathered regions and an avian-like condition in feathered regions. Retention of reptile-type skin in non-feathered regions would have ensured essential skin functions during the early, experimental stages of feather evolution.
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Affiliation(s)
- Zixiao Yang
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland.
- Environmental Research Institute, University College Cork, Cork, Ireland.
| | - Baoyu Jiang
- State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering and Frontiers Science Center for Critical Earth Material Cycling, Nanjing University, Nanjing, China
| | - Jiaxin Xu
- State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering and Frontiers Science Center for Critical Earth Material Cycling, Nanjing University, Nanjing, China
| | - Maria E McNamara
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
- Environmental Research Institute, University College Cork, Cork, Ireland
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3
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Falk D, Wings O, Unitt R, Wade J, McNamara ME. Fossilized anuran soft tissues reveal a new taphonomic model for the Eocene Geiseltal Konservat-Lagerstätte, Germany. Sci Rep 2024; 14:7876. [PMID: 38654038 DOI: 10.1038/s41598-024-55822-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 02/28/2024] [Indexed: 04/25/2024] Open
Abstract
The Eocene Geiseltal Konservat-Lagerstätte (Germany) is famous for reports of three dimensionally preserved soft tissues with sub-cellular detail. The proposed mode of preservation, direct replication in silica, is not known in other fossils and has not been verified using modern approaches. Here, we investigated the taphonomy of the Geiseltal anurans using diverse microbeam imaging and chemical analytical techniques. Our analyses confirm the preservation of soft tissues in all body regions but fail to yield evidence for silicified soft tissues. Instead, the anuran soft tissues are preserved as two layers that differ in microstructure and composition. Layer 1 comprises sulfur-rich carbonaceous microbodies interpreted as melanosomes. Layer 2 comprises the mid-dermal Eberth-Katschenko layer, preserved in calcium phosphate. In addition, patches of original aragonite crystals define the former position of the endolymphatic sac. The primary modes of soft tissue preservation are therefore sulfurization of melanosomes and phosphatization of more labile soft tissues, i.e., skin. This is consistent with the taphonomy of vertebrates in many other Konservat-Lagerstätten. These findings emphasize an emerging model for pervasive preservation of vertebrate soft tissues via melanosome films, particularly in stagnation-type deposits, with phosphatization of more labile tissues where tissue biochemistry is favorable.
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Affiliation(s)
- Daniel Falk
- School of Biological, Earth and Environmental Sciences, University College Cork, Distillery Fields, North Mall, Cork, T23 TK30, Ireland.
- Environmental Research Institute, University College Cork, Lee Rd, Cork, T23 XE10, Ireland.
| | - Oliver Wings
- Natural History Museum Bamberg, Staatliche Naturwissenschaftliche Sammlungen Bayerns, Fleischstraße 2, 96047, Bamberg, Germany
| | - Richard Unitt
- School of Biological, Earth and Environmental Sciences, University College Cork, Distillery Fields, North Mall, Cork, T23 TK30, Ireland
- Environmental Research Institute, University College Cork, Lee Rd, Cork, T23 XE10, Ireland
- Copper Coast UNESCO Global Geopark, Knockmahon, Bunmahon, X42 T923, Ireland
| | - Jon Wade
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, UK
| | - Maria E McNamara
- School of Biological, Earth and Environmental Sciences, University College Cork, Distillery Fields, North Mall, Cork, T23 TK30, Ireland
- Environmental Research Institute, University College Cork, Lee Rd, Cork, T23 XE10, Ireland
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4
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Slater TS, McNamara ME, Orr PJ, Foley TB, Ito S, Wakamatsu K. Taphonomic experiments resolve controls on the preservation of melanosomes and keratinous tissues in feathers. PALAEONTOLOGY 2020; 63:103-115. [PMID: 32025055 PMCID: PMC6988486 DOI: 10.1111/pala.12445] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/15/2019] [Indexed: 06/10/2023]
Abstract
Fossils are a key source of data on the evolution of feather structure and function through deep time, but their ability to resolve macroevolutionary questions is compromised by an incomplete understanding of their taphonomy. Critically, the relative preservation potential of two key feather components, melanosomes and keratinous tissue, is not fully resolved. Recent studies suggesting that melanosomes are preferentially preserved conflict with observations that melanosomes preserve in fossil feathers as external moulds in an organic matrix. To date, there is no model to explain the latter mode of melanosome preservation. We addressed these issues by degrading feathers in systematic taphonomic experiments incorporating decay, maturation and oxidation in isolation and combination. Our results reveal that the production of mouldic melanosomes requires interactions with an oxidant and is most likely to occur prior to substantial maturation. This constrains the taphonomic conditions under which melanosomes are likely to be fossilized. Critically, our experiments also confirm that keratinous feather structures have a higher preservation potential than melanosomes under a range of diagenetic conditions, supporting hitherto controversial hypotheses that fossil feathers can retain degraded keratinous structures.
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Affiliation(s)
- Tiffany S. Slater
- School of Biological, Earth & Environmental SciencesUniversity College CorkCorkIreland
| | - Maria E. McNamara
- School of Biological, Earth & Environmental SciencesUniversity College CorkCorkIreland
| | - Patrick J. Orr
- UCDSchool of Earth SciencesUniversity College DublinDublinIreland
| | - Tara B. Foley
- Department of Anatomy & NeuroscienceUniversity College CorkCorkIreland
| | - Shosuke Ito
- Department of ChemistryFujita Health University School of Health SciencesToyoakeAichiJapan
| | - Kazumasa Wakamatsu
- Department of ChemistryFujita Health University School of Health SciencesToyoakeAichiJapan
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5
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Pinheiro FL, Prado G, Ito S, Simon JD, Wakamatsu K, Anelli LE, Andrade JAF, Glass K. Chemical characterization of pterosaur melanin challenges color inferences in extinct animals. Sci Rep 2019; 9:15947. [PMID: 31685890 PMCID: PMC6828676 DOI: 10.1038/s41598-019-52318-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 10/11/2019] [Indexed: 12/18/2022] Open
Abstract
Melanosomes (melanin-bearing organelles) are common in the fossil record occurring as dense packs of globular microbodies. The organic component comprising the melanosome, melanin, is often preserved in fossils, allowing identification of the chemical nature of the constituent pigment. In present-day vertebrates, melanosome morphology correlates with their pigment content in selected melanin-containing structures, and this interdependency is employed in the color reconstruction of extinct animals. The lack of analyses integrating the morphology of fossil melanosomes with the chemical identification of pigments, however, makes these inferences tentative. Here, we chemically characterize the melanin content of the soft tissue headcrest of the pterosaur Tupandactylus imperator by alkaline hydrogen peroxide oxidation followed by high-performance liquid chromatography. Our results demonstrate the unequivocal presence of eumelanin in T. imperator headcrest. Scanning electron microscopy followed by statistical analyses, however, reveal that preserved melanosomes containing eumelanin are undistinguishable to pheomelanin-bearing organelles of extant vertebrates. Based on these new findings, straightforward color inferences based on melanosome morphology may not be valid for all fossil vertebrates, and color reconstructions based on ultrastructure alone should be regarded with caution.
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Affiliation(s)
- Felipe L Pinheiro
- Laboratório de Paleobiologia, Universidade Federal do Pampa, São Gabriel, 97300-162, Brazil.
| | - Gustavo Prado
- Instituto de Geociências, Universidade de São Paulo, São Paulo, Brazil.
| | - Shosuke Ito
- Department of Chemistry, Fujita Health University School of Medical Sciences, Toyoake, Aichi, 470-1192, Japan
| | | | - Kazumasa Wakamatsu
- Department of Chemistry, Fujita Health University School of Medical Sciences, Toyoake, Aichi, 470-1192, Japan
| | - Luiz E Anelli
- Instituto de Geociências, Universidade de São Paulo, São Paulo, Brazil
| | - José A F Andrade
- Centro de Pesquisas Paleontológicas da Chapada do Araripe, Departamento Nacional de Produção Mineral, 63100-440, Crato, Brazil
| | - Keely Glass
- Department of Chemistry, Duke University, Durham, NC, 27708, USA
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6
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Combined microscopy and spectroscopy techniques to characterize a fossilized feather with minimal damage to the specimen. Micron 2019; 120:17-24. [DOI: 10.1016/j.micron.2019.01.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 01/28/2019] [Accepted: 01/30/2019] [Indexed: 11/20/2022]
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7
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Gabbott SE, Donoghue PCJ, Sansom RS, Vinther J, Dolocan A, Purnell MA. Pigmented anatomy in Carboniferous cyclostomes and the evolution of the vertebrate eye. Proc Biol Sci 2017; 283:rspb.2016.1151. [PMID: 27488650 PMCID: PMC5013770 DOI: 10.1098/rspb.2016.1151] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 07/11/2016] [Indexed: 12/03/2022] Open
Abstract
The success of vertebrates is linked to the evolution of a camera-style eye and sophisticated visual system. In the absence of useful data from fossils, scenarios for evolutionary assembly of the vertebrate eye have been based necessarily on evidence from development, molecular genetics and comparative anatomy in living vertebrates. Unfortunately, steps in the transition from a light-sensitive ‘eye spot’ in invertebrate chordates to an image-forming camera-style eye in jawed vertebrates are constrained only by hagfish and lampreys (cyclostomes), which are interpreted to reflect either an intermediate or degenerate condition. Here, we report—based on evidence of size, shape, preservation mode and localized occurrence—the presence of melanosomes (pigment-bearing organelles) in fossil cyclostome eyes. Time of flight secondary ion mass spectrometry analyses reveal secondary ions with a relative intensity characteristic of melanin as revealed through principal components analyses. Our data support the hypotheses that extant hagfish eyes are degenerate, not rudimentary, that cyclostomes are monophyletic, and that the ancestral vertebrate had a functional visual system. We also demonstrate integument pigmentation in fossil lampreys, opening up the exciting possibility of investigating colour patterning in Palaeozoic vertebrates. The examples we report add to the record of melanosome preservation in Carboniferous fossils and attest to surprising durability of melanosomes and biomolecular melanin.
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Affiliation(s)
- Sarah E Gabbott
- Department of Geology, University of Leicester, Leicester LE1 7RH, UK
| | | | - Robert S Sansom
- Faculty of Life Sciences, University of Manchester, Manchester M20 6RT, UK
| | - Jakob Vinther
- Department of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK
| | - Andrei Dolocan
- Texas Materials Institute, The University of Texas at Austin, Austin, TX 78712, USA
| | - Mark A Purnell
- Department of Geology, University of Leicester, Leicester LE1 7RH, UK
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8
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Devault AM, Mortimer TD, Kitchen A, Kiesewetter H, Enk JM, Golding GB, Southon J, Kuch M, Duggan AT, Aylward W, Gardner SN, Allen JE, King AM, Wright G, Kuroda M, Kato K, Briggs DE, Fornaciari G, Holmes EC, Poinar HN, Pepperell CS. A molecular portrait of maternal sepsis from Byzantine Troy. eLife 2017; 6. [PMID: 28072390 PMCID: PMC5224923 DOI: 10.7554/elife.20983] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 11/24/2016] [Indexed: 12/14/2022] Open
Abstract
Pregnancy complications are poorly represented in the archeological record, despite their importance in contemporary and ancient societies. While excavating a Byzantine cemetery in Troy, we discovered calcified abscesses among a woman’s remains. Scanning electron microscopy of the tissue revealed ‘ghost cells’, resulting from dystrophic calcification, which preserved ancient maternal, fetal and bacterial DNA of a severe infection, likely chorioamnionitis. Gardnerella vaginalis and Staphylococcus saprophyticus dominated the abscesses. Phylogenomic analyses of ancient, historical, and contemporary data showed that G. vaginalis Troy fell within contemporary genetic diversity, whereas S. saprophyticus Troy belongs to a lineage that does not appear to be commonly associated with human disease today. We speculate that the ecology of S. saprophyticus infection may have differed in the ancient world as a result of close contacts between humans and domesticated animals. These results highlight the complex and dynamic interactions with our microbial milieu that underlie severe maternal infections. DOI:http://dx.doi.org/10.7554/eLife.20983.001 Why and how have some bacteria evolved to cause illness in humans? One way to study bacterial evolution is to search for ancient samples of bacteria and use DNA sequencing technology to investigate how modern bacteria have changed from their ancestors. Understanding the evolution process may help researchers to understand how some bacteria become resistant to the antibiotics designed to kill them. Complications that occur during pregnancy, including bacterial infections, have long been a major cause of death for women. Now, Devault, Mortimer et al. have been able to sequence the DNA of bacteria found in tissue collected from a woman buried 800 years ago in a cemetery in Troy. Some of the woman’s tissues had been well preserved because they had calcified (probably as the result of infection), which preserved their structure in a mineralized layer. Two mineralized “nodules” in the body appear to be the remains of abscesses. Some of the human DNA in the nodules came from a male, suggesting that the woman was pregnant with a boy and that the abscesses formed in placental tissue. Sequencing the DNA of the bacteria in the abscess allowed Devault, Mortimer et al. to diagnose the woman’s infection, which was caused by two types of bacteria. One species, called Gardnerella vaginalis, is found in modern pregnancy-related infections. The DNA of the ancient samples was similar to that of modern bacteria. The other bacteria species was an ancient form of Staphylococcus saprophyticus, a type of bacteria that causes urinary tract infections. However, the DNA of the ancient S. saprophyticus bacteria is quite different to that of the bacteria found in modern humans. Instead, their DNA sequence appears more similar to forms of the bacteria that infect currently livestock. As humans lived closely with their livestock at the time the woman lived, her infection may be due to a type of bacteria that passed easily between humans and animals. Overall, the results suggest that the disease-causing properties of bacteria can arise from a wide range of sources. In addition, Devault, Mortimer et al. have demonstrated that certain types of tissue found in archeological remains are a potential gold mine of information about the evolution of bacteria and other microbes found in the human body. DOI:http://dx.doi.org/10.7554/eLife.20983.002
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Affiliation(s)
- Alison M Devault
- McMaster Ancient DNA Centre, Department of Anthropology, McMaster University, Hamilton, Canada.,MYcroarray, Ann Arbor, United States
| | - Tatum D Mortimer
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, United States.,Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, United States
| | - Andrew Kitchen
- Department of Anthropology, University of Iowa, Iowa City, United States
| | - Henrike Kiesewetter
- Project Troia, Institute of Prehistory, Early History, and Medieval Archaeology, Tübingen University, Tübingen, Germany
| | - Jacob M Enk
- McMaster Ancient DNA Centre, Department of Anthropology, McMaster University, Hamilton, Canada.,MYcroarray, Ann Arbor, United States
| | - G Brian Golding
- Department of Biology, McMaster University, Hamilton, Canada
| | - John Southon
- Keck Carbon Cycle Accelerator Mass Spectrometer, Earth Systems Science Department, University of California, Irvine, United States
| | - Melanie Kuch
- McMaster Ancient DNA Centre, Department of Anthropology, McMaster University, Hamilton, Canada
| | - Ana T Duggan
- McMaster Ancient DNA Centre, Department of Anthropology, McMaster University, Hamilton, Canada
| | - William Aylward
- Molecular Archaeology Laboratory, Biotechnology Center, University of Wisconsin-Madison, Madison, United States.,Department of Classics and Ancient Near Eastern Studies, University of Wisconsin-Madison, Madison, United States
| | - Shea N Gardner
- Lawrence Livermore National Laboratory, Livermore, United States
| | - Jonathan E Allen
- Lawrence Livermore National Laboratory, Livermore, United States
| | - Andrew M King
- Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Canada
| | - Gerard Wright
- Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Canada
| | - Makoto Kuroda
- Laboratory of Bacterial Genomics, Pathogen Genomics Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kengo Kato
- Laboratory of Bacterial Genomics, Pathogen Genomics Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Derek Eg Briggs
- Department of Geology and Geophysics, Yale University, New Haven, United States
| | - Gino Fornaciari
- Division of Paleopathology, Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Edward C Holmes
- Marie Bashir Institute for Infectious Diseases and Biosecurity, Charles Perkins Centre, School of Life and Environmental Sciences and Sydney Medical School, The University of Sydney, Sydney, Australia
| | - Hendrik N Poinar
- McMaster Ancient DNA Centre, Department of Anthropology, McMaster University, Hamilton, Canada.,Department of Biology, McMaster University, Hamilton, Canada.,Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Canada.,Humans and the Microbiome Program, Canadian Institute for Advanced Research, Toronto, Canada
| | - Caitlin S Pepperell
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, United States.,Molecular Archaeology Laboratory, Biotechnology Center, University of Wisconsin-Madison, Madison, United States.,Department of Medicine (Infectious Diseases), School of Medicine and Public Health, University of Wisconsin-Madison, Madison, United States
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9
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Galván I, Solano F. Bird Integumentary Melanins: Biosynthesis, Forms, Function and Evolution. Int J Mol Sci 2016; 17:520. [PMID: 27070583 PMCID: PMC4848976 DOI: 10.3390/ijms17040520] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 03/27/2016] [Accepted: 03/30/2016] [Indexed: 11/16/2022] Open
Abstract
Melanins are the ubiquitous pigments distributed in nature. They are one of the main pigments responsible for colors in living cells. Birds are among the most diverse animals regarding melanin-based coloration, especially in the plumage, although they also pigment bare parts of the integument. This review is devoted to the main characteristics of bird melanins, including updated views of the formation and nature of melanin granules, whose interest has been raised in the last years for inferring the color of extinct birds and non-avian theropod dinosaurs using resistant fossil feathers. The molecular structure of the two main types of melanin, eumelanin and pheomelanin, and the environmental and genetic factors that regulate avian melanogenesis are also presented, establishing the main relationship between them. Finally, the special functions of melanin in bird feathers are also discussed, emphasizing the aspects more closely related to these animals, such as honest signaling, and the factors that may drive the evolution of pheomelanin and pheomelanin-based color traits, an issue for which birds have been pioneer study models.
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Affiliation(s)
- Ismael Galván
- Department of Evolutionary Ecology, Doñana Biological Station-CSIC, 41092 Sevilla, Spain.
| | - Francisco Solano
- Department of Biochemistry and Molecular Biology B & Immunology, School of Medicine and IMIB, University of Murcia, 30100 Murcia, Spain.
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