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Chen J, Wang H, Wu S, Zhang A, Qiu Z, Huang P, Qu JY, Xu J. col1a2+ fibroblasts/muscle progenitors finetune xanthophore countershading by differentially expressing csf1a/1b in embryonic zebrafish. SCIENCE ADVANCES 2024; 10:eadj9637. [PMID: 38578990 PMCID: PMC10997200 DOI: 10.1126/sciadv.adj9637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 02/29/2024] [Indexed: 04/07/2024]
Abstract
Animals evolve diverse pigment patterns to adapt to the natural environment. Countershading, characterized by a dark-colored dorsum and a light-colored ventrum, is one of the most prevalent pigment patterns observed in vertebrates. In this study, we reveal a mechanism regulating xanthophore countershading in zebrafish embryos. We found that csf1a and csf1b mutants altered xanthophore countershading differently: csf1a mutants lack ventral xanthophores, while csf1b mutants have reduced dorsal xanthophores. Further study revealed that csf1a is expressed throughout the trunk, whereas csf1b is expressed dorsally. Ectopic expression of csf1a or csf1b in neurons attracted xanthophores into the spinal cord. Blocking csf1 signaling by csf1ra mutants disrupts spinal cord distribution and normal xanthophores countershading. Single-cell RNA sequencing identified two col1a2+ populations: csf1ahighcsf1bhigh muscle progenitors and csf1ahighcsf1blow fibroblast progenitors. Ablation of col1a2+ fibroblast and muscle progenitors abolished xanthophore patterns. Our study suggests that fibroblast and muscle progenitors differentially express csf1a and csf1b to modulate xanthophore patterning, providing insights into the mechanism of countershading.
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Affiliation(s)
- Jiahao Chen
- Department of Neurology, the Second Affiliated Hospital, School of Medicine, South China University of Technology, Guangzhou 510006, China
- Innovation Centre of Ministry of Education for Development and Diseases, School of Medicine, South China University of Technology, Guangzhou 510006, China
| | - Honggao Wang
- Innovation Centre of Ministry of Education for Development and Diseases, School of Medicine, South China University of Technology, Guangzhou 510006, China
| | - Shuting Wu
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Ao Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PRC
| | - Zhongkai Qiu
- Innovation Centre of Ministry of Education for Development and Diseases, School of Medicine, South China University of Technology, Guangzhou 510006, China
| | - Peng Huang
- Department of Biochemistry and Molecular Biology, Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Jianan Y Qu
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Kowloon, China
| | - Jin Xu
- Department of Neurology, the Second Affiliated Hospital, School of Medicine, South China University of Technology, Guangzhou 510006, China
- Innovation Centre of Ministry of Education for Development and Diseases, School of Medicine, South China University of Technology, Guangzhou 510006, China
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2
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Steel R, Hamed M, Haugom JT, Ho T, Kenner N, Malfavon-Borja J, Morgans S, Salek SA, Seylani A, Jancovich JK. Age- and dose-dependent susceptibility of axolotls (Ambystoma mexicanum) by bath exposure to Ambystoma tigrinum virus (ATV). Virology 2023; 588:109909. [PMID: 37879268 DOI: 10.1016/j.virol.2023.109909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 10/04/2023] [Accepted: 10/09/2023] [Indexed: 10/27/2023]
Abstract
Ranaviruses are large, dsDNA viruses that have significant ecological and economic impact on cold-blooded vertebrates. However, our understanding of the viral proteins and subsequent host immune response(s) that impact susceptibility to infection and disease is not clear. The ranavirus Ambystoma tigrinum virus (ATV), originally isolated from the Sonoran tiger salamander (Ambystoma mavortium stebbinsi), is highly pathogenic at low doses of ATV at all tiger salamander life stages and this model has been used to explore the host-pathogen interactions of ATV infection. However, inconsistencies in the availability of laboratory reared larval tiger salamanders required us to look at the well characterized axolotl (A. mexicanum) as a model for ATV infection. Data obtained from five infection experiments over different developmental timepoints suggest that axolotls are susceptible to ATV in an age- and dose-dependent manner. These data support the use of the ATV-axolotl model to further explore the host-pathogen interactions of ranavirus infections.
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Affiliation(s)
- Riley Steel
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, 92078, USA
| | - Michelle Hamed
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, 92078, USA
| | - Josefine T Haugom
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, 92078, USA
| | - Trang Ho
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, 92078, USA
| | - Nathaniel Kenner
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, 92078, USA
| | - Joanna Malfavon-Borja
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, 92078, USA
| | - Scott Morgans
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, 92078, USA
| | - Savannah A Salek
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, 92078, USA
| | - Allen Seylani
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, 92078, USA
| | - James K Jancovich
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, 92078, USA.
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3
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Elkin J, Martin A, Courtier-Orgogozo V, Santos ME. Analysis of the genetic loci of pigment pattern evolution in vertebrates. Biol Rev Camb Philos Soc 2023; 98:1250-1277. [PMID: 37017088 DOI: 10.1111/brv.12952] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/08/2023] [Accepted: 03/14/2023] [Indexed: 04/06/2023]
Abstract
Vertebrate pigmentation patterns are amongst the best characterised model systems for studying the genetic basis of adaptive evolution. The wealth of available data on the genetic basis for pigmentation evolution allows for analysis of trends and quantitative testing of evolutionary hypotheses. We employed Gephebase, a database of genetic variants associated with natural and domesticated trait variation, to examine trends in how cis-regulatory and coding mutations contribute to vertebrate pigmentation phenotypes, as well as factors that favour one mutation type over the other. We found that studies with lower ascertainment bias identified higher proportions of cis-regulatory mutations, and that cis-regulatory mutations were more common amongst animals harbouring a higher number of pigment cell classes. We classified pigmentation traits firstly according to their physiological basis and secondly according to whether they affect colour or pattern, and identified that carotenoid-based pigmentation and variation in pattern boundaries are preferentially associated with cis-regulatory change. We also classified genes according to their developmental, cellular, and molecular functions. We found a greater proportion of cis-regulatory mutations in genes implicated in upstream developmental processes compared to those involved in downstream cellular functions, and that ligands were associated with a higher proportion of cis-regulatory mutations than their respective receptors. Based on these trends, we discuss future directions for research in vertebrate pigmentation evolution.
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Affiliation(s)
- Joel Elkin
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
| | - Arnaud Martin
- Department of Biological Sciences, The George Washington University, 800 22nd St. NW, Suite 6000, Washington, DC, 20052, USA
| | | | - M Emília Santos
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
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Dao UM, Lederer I, Tabor RL, Shahid B, Graves CW, Seidel HS. Stripes and loss of color in ball pythons (Python regius) are associated with variants affecting endothelin signaling. G3 (BETHESDA, MD.) 2023; 13:jkad063. [PMID: 37191439 PMCID: PMC10320763 DOI: 10.1093/g3journal/jkad063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 03/10/2023] [Indexed: 05/17/2023]
Abstract
Color patterns in nonavian reptiles are beautifully diverse, but little is known about the genetics and development of these patterns. Here, we investigated color patterning in pet ball pythons (Python regius), which have been bred to show color phenotypes that differ dramatically from the wildtype form. We report that several color phenotypes in pet animals are associated with putative loss-of-function variants in the gene encoding endothelin receptor EDNRB1: (1) frameshift variants in EDNRB1 are associated with conversion of the normal mottled color pattern to skin that is almost fully white, (2) missense variants affecting conserved sites of the EDNRB1 protein are associated with dorsal, longitudinal stripes, and (3) substitutions at EDNRB1 splice donors are associated with subtle changes in patterning compared to wildtype. We propose that these phenotypes are caused by loss of specialized color cells (chromatophores), with loss ranging from severe (fully white) to moderate (dorsal striping) to mild (subtle changes in patterning). Our study is the first to describe variants affecting endothelin signaling in a nonavian reptile and suggests that reductions in endothelin signaling in ball pythons can produce a variety of color phenotypes, depending on the degree of color cell loss.
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Affiliation(s)
- Uyen M Dao
- Department of Biology, Eastern Michigan University, Ypsilanti, MI 48197, USA
| | - Izabella Lederer
- Department of Biology, Eastern Michigan University, Ypsilanti, MI 48197, USA
| | - Ray L Tabor
- Department of Biology, Eastern Michigan University, Ypsilanti, MI 48197, USA
| | - Basmah Shahid
- Department of Biology, Eastern Michigan University, Ypsilanti, MI 48197, USA
| | - Chiron W Graves
- Department of Biology, Eastern Michigan University, Ypsilanti, MI 48197, USA
| | - Hannah S Seidel
- Department of Biology, Eastern Michigan University, Ypsilanti, MI 48197, USA
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5
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Kabangu M, Cecil R, Strohl L, Timoshevskaya N, Smith JJ, Voss SR. Leukocyte Tyrosine Kinase ( Ltk) Is the Mendelian Determinant of the Axolotl Melanoid Color Variant. Genes (Basel) 2023; 14:904. [PMID: 37107662 PMCID: PMC10137446 DOI: 10.3390/genes14040904] [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: 02/23/2023] [Revised: 04/02/2023] [Accepted: 04/10/2023] [Indexed: 04/29/2023] Open
Abstract
The great diversity of color patterns observed among amphibians is largely explained by the differentiation of relatively few pigment cell types during development. Mexican axolotls present a variety of color phenotypes that span the continuum from leucistic to highly melanistic. The melanoid axolotl is a Mendelian variant characterized by large numbers of melanophores, proportionally fewer xanthophores, and no iridophores. Early studies of melanoid were influential in developing the single-origin hypothesis of pigment cell development, wherein it has been proposed that all three pigment cell types derive from a common progenitor cell, with pigment metabolites playing potential roles in directing the development of organelles that define different pigment cell types. Specifically, these studies identified xanthine dehydrogenase (XDH) activity as a mechanism for the permissive differentiation of melanophores at the expense of xanthophores and iridophores. We used bulked segregant RNA-Seq to screen the axolotl genome for melanoid candidate genes and identify the associated locus. Dissimilar frequencies of single-nucleotide polymorphisms were identified between pooled RNA samples of wild-type and melanoid siblings for a region on chromosome 14q. This region contains gephyrin (Gphn), an enzyme that catalyzes the synthesis of the molybdenum cofactor that is required for XDH activity, and leukocyte tyrosine kinase (Ltk), a cell surface signaling receptor that is required for iridophore differentiation in zebrafish. Wild-type Ltk crispants present similar pigment phenotypes to melanoid, strongly implicating Ltk as the melanoid locus. In concert with recent findings in zebrafish, our results support the idea of direct fate specification of pigment cells and, more generally, the single-origin hypothesis of pigment cell development.
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Affiliation(s)
- Mirindi Kabangu
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, and Ambystoma Genetic Stock Center, University of Kentucky, Lexington, KY 40536, USA
- Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Raissa Cecil
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, and Ambystoma Genetic Stock Center, University of Kentucky, Lexington, KY 40536, USA
| | | | | | - Jeramiah J. Smith
- Department of Biology, University of Kentucky, Lexington, KY 40506, USA
| | - Stephen R. Voss
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, and Ambystoma Genetic Stock Center, University of Kentucky, Lexington, KY 40536, USA
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6
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Lovely AM, Duerr TJ, Stein DF, Mun ET, Monaghan JR. Hybridization Chain Reaction Fluorescence In Situ Hybridization (HCR-FISH) in Ambystoma mexicanum Tissue. Methods Mol Biol 2023; 2562:109-122. [PMID: 36272070 PMCID: PMC10949069 DOI: 10.1007/978-1-0716-2659-7_6] [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] [Indexed: 02/12/2023]
Abstract
In situ hybridization is a standard procedure for visualizing mRNA transcripts in tissues. The recent adoption of fluorescent probes and new signal amplification methods have facilitated multiplexed RNA imaging in tissue sections and whole tissues. Here we present protocols for multiplexed hybridization chain reaction fluorescence in situ hybridization (HCR-FISH) staining, imaging, cell segmentation, and mRNA quantification in regenerating axolotl tissue sections. We also present a protocol for whole-mount staining and imaging of developing axolotl limbs.
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Affiliation(s)
- Alex M Lovely
- Department of Biology, Northeastern University, Boston, MA, USA
- Northeastern University, Institute for Chemical Imaging of Living Systems, Boston, MA, USA
| | - Timothy J Duerr
- Department of Biology, Northeastern University, Boston, MA, USA
| | - David F Stein
- Department of Biology, Northeastern University, Boston, MA, USA
| | - Evan T Mun
- Department of Biology, Northeastern University, Boston, MA, USA
| | - James R Monaghan
- Department of Biology, Northeastern University, Boston, MA, USA.
- Northeastern University, Institute for Chemical Imaging of Living Systems, Boston, MA, USA.
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7
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Keinath M, Timoshevskiy V. Fluorescence In Situ Hybridization of DNA Probes on Mitotic Chromosomes of the Mexican Axolotl. Methods Mol Biol 2023; 2562:165-173. [PMID: 36272074 DOI: 10.1007/978-1-0716-2659-7_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Fluorescence in situ hybridization (FISH) is used extensively for visual localization of specific DNA fragments (and RNA fragments) in broad applications on chromosomes or nuclei at any stage of the cell cycle: metaphase, anaphase, or interphase. The cytogenetic slides that serve as a target for the labeled DNA probe might be prepared using any approach suitable for obtaining cells with appropriate morphology for imaging and analysis. In this chapter, we focus on the application of molecular cytogenetic methods such as DNA labeling, slide preparation, and in situ hybridization related to cells from Mexican axolotl.
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Affiliation(s)
- Melissa Keinath
- Carnegie Institute of Science Department of Embryology (Lab 322), Baltimore, MD, USA
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8
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Paldi RL, Kalaswad M, Lu J, Barnard JP, Richter NA, Si M, Bhatt NA, Ye PD, Sarma R, Siddiqui A, Huang J, Zhang X, Wang H. ZnO-ferromagnetic metal vertically aligned nanocomposite thin films for magnetic, optical and acoustic metamaterials. NANOSCALE ADVANCES 2022; 5:247-254. [PMID: 36605792 PMCID: PMC9765661 DOI: 10.1039/d2na00444e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Accepted: 10/31/2022] [Indexed: 06/17/2023]
Abstract
Magnetoacoustic waves generated in piezoelectric and ferromagnetic coupled nanocomposite films through magnetically driven surface acoustic waves present great promise of loss-less data transmission. In this work, ferromagnetic metals of Ni, Co and Co x Ni1-x are coupled with a piezoelectric ZnO matrix in a vertically-aligned nanocomposite (VAN) thin film platform. Oxidation was found to occur in the cases of ZnO-Co, forming a ZnO-CoO VAN, while only very minor oxidation was found in the case of ZnO-Ni VAN. An alloy approach of Co x Ni1-x has been explored to overcome the oxidation during growth. Detailed microstructural analysis reveals limited oxidation of both metals and distinct phase separation between the ZnO and the metallic phases. Highly anisotropic properties including anisotropic ferromagnetic properties and hyperbolic dielectric functions are found in the ZnO-Ni and ZnO-Co x Ni1-x systems. The magnetic metal-ZnO-based hybrid metamaterials in this report present great potential in coupling of optical, magnetic, and piezoelectric properties towards future magnetoacoustic wave devices.
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Affiliation(s)
- Robynne L Paldi
- School of Materials Engineering, Purdue University West Lafayette Indiana 47907 USA
| | - Matias Kalaswad
- School of Electrical and Computer Engineering, Purdue University West Lafayette Indiana 47907 USA
| | - Juanjuan Lu
- School of Materials Engineering, Purdue University West Lafayette Indiana 47907 USA
| | - James P Barnard
- School of Materials Engineering, Purdue University West Lafayette Indiana 47907 USA
| | - Nicholas A Richter
- School of Materials Engineering, Purdue University West Lafayette Indiana 47907 USA
| | - Mengwei Si
- School of Electrical and Computer Engineering, Purdue University West Lafayette Indiana 47907 USA
- Birck Nanotechnology Center, Purdue University West Lafayette 47907 USA
| | - Nirali A Bhatt
- School of Materials Engineering, Purdue University West Lafayette Indiana 47907 USA
| | - Peide D Ye
- School of Electrical and Computer Engineering, Purdue University West Lafayette Indiana 47907 USA
- Birck Nanotechnology Center, Purdue University West Lafayette 47907 USA
| | | | | | - Jijie Huang
- School of Materials, Sun Yat-sen University Guangzhou Guangdong 510275 China
| | - Xinghang Zhang
- School of Materials Engineering, Purdue University West Lafayette Indiana 47907 USA
| | - Haiyan Wang
- School of Materials Engineering, Purdue University West Lafayette Indiana 47907 USA
- School of Electrical and Computer Engineering, Purdue University West Lafayette Indiana 47907 USA
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9
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Adaptive coding for DNA storage with high storage density and low coverage. NPJ Syst Biol Appl 2022; 8:23. [PMID: 35788589 PMCID: PMC9253015 DOI: 10.1038/s41540-022-00233-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 06/10/2022] [Indexed: 11/09/2022] Open
Abstract
The rapid development of information technology has generated substantial data, which urgently requires new storage media and storage methods. DNA, as a storage medium with high density, high durability, and ultra-long storage time characteristics, is promising as a potential solution. However, DNA storage is still in its infancy and suffers from low space utilization of DNA strands, high read coverage, and poor coding coupling. Therefore, in this work, an adaptive coding DNA storage system is proposed to use different coding schemes for different coding region locations, and the method of adaptively generating coding constraint thresholds is used to optimize at the system level to ensure the efficient operation of each link. Images, videos, and PDF files of size 698 KB were stored in DNA using adaptive coding algorithms. The data were sequenced and losslessly decoded into raw data. Compared with previous work, the DNA storage system implemented by adaptive coding proposed in this paper has high storage density and low read coverage, which promotes the development of carbon-based storage systems.
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Haynes EM, Ulland TK, Eliceiri KW. A Model of Discovery: The Role of Imaging Established and Emerging Non-mammalian Models in Neuroscience. Front Mol Neurosci 2022; 15:867010. [PMID: 35493325 PMCID: PMC9046975 DOI: 10.3389/fnmol.2022.867010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/18/2022] [Indexed: 11/24/2022] Open
Abstract
Rodents have been the dominant animal models in neurobiology and neurological disease research over the past 60 years. The prevalent use of rats and mice in neuroscience research has been driven by several key attributes including their organ physiology being more similar to humans, the availability of a broad variety of behavioral tests and genetic tools, and widely accessible reagents. However, despite the many advances in understanding neurobiology that have been achieved using rodent models, there remain key limitations in the questions that can be addressed in these and other mammalian models. In particular, in vivo imaging in mammals at the cell-resolution level remains technically difficult and demands large investments in time and cost. The simpler nervous systems of many non-mammalian models allow for precise mapping of circuits and even the whole brain with impressive subcellular resolution. The types of non-mammalian neuroscience models available spans vertebrates and non-vertebrates, so that an appropriate model for most cell biological questions in neurodegenerative disease likely exists. A push to diversify the models used in neuroscience research could help address current gaps in knowledge, complement existing rodent-based bodies of work, and bring new insight into our understanding of human disease. Moreover, there are inherent aspects of many non-mammalian models such as lifespan and tissue transparency that can make them specifically advantageous for neuroscience studies. Crispr/Cas9 gene editing and decreased cost of genome sequencing combined with advances in optical microscopy enhances the utility of new animal models to address specific questions. This review seeks to synthesize current knowledge of established and emerging non-mammalian model organisms with advances in cellular-resolution in vivo imaging techniques to suggest new approaches to understand neurodegeneration and neurobiological processes. We will summarize current tools and in vivo imaging approaches at the single cell scale that could help lead to increased consideration of non-mammalian models in neuroscience research.
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Affiliation(s)
- Elizabeth M. Haynes
- Morgridge Institute for Research, Madison, WI, United States
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI, United States
| | - Tyler K. Ulland
- Department of Pathology, University of Wisconsin-Madison, Madison, WI, United States
| | - Kevin W. Eliceiri
- Morgridge Institute for Research, Madison, WI, United States
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI, United States
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States
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11
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Chang L, Zhu W, Jiang J. Albinism in the largest extant amphibian: A metabolic, endocrine, or immune problem? Front Endocrinol (Lausanne) 2022; 13:1053732. [PMID: 36518250 PMCID: PMC9742363 DOI: 10.3389/fendo.2022.1053732] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 11/07/2022] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Pigment regression is an intriguing phenomenon that can be caused by disorders in melanin metabolism or endocrine regulation, or by autoimmune disorders. Albino animals serve as excellent models for the study of the genetic determination of morphology, particularly the evolution of and molecular mechanisms underlying chromatophore-related diseases in animals and humans. MATERIAL AND METHODS The artificial culture of Andrias davidianus, the largest extant amphibian, is flourishing in China due to the great ecological and economic value of this animal. Approximately 0.1% of individuals express an albino phenotype accompanied by delayed somatic growth and mortality at early developmental stages. In this study, brain and skin transcriptomics were conducted to study the underlying molecular basis of the phenotype. RESULTS The results indicated decreased transcription of genes of melanin synthesis. Interestingly, MHC I isotypes and immune-related pathways accounted for the primary transcriptional differences between groups, suggesting that the albino phenotype represents a systematic immune problem to a far greater extent than a pigmentation defect. Albino individuals exhibited shifted transcription of MHC I isotypes, and the albino-specific isotype was characterized by increased charges and decreased space in the antigen- binding pocket, implying a drastic change in antigen specificity and a potential risk of autoimmune disorders. CONCLUSION These results suggest an association between the albino phenotype and MHC I variants in A. davidianus, which could serve as a convenient model for vitiligo or other autoimmune diseases.
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12
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Cai X, Sun G, Xu Y, Ma J, Xu D. Effect of hydrogenation on the thermal conductivity of 2D gallium nitride. Phys Chem Chem Phys 2021; 23:22423-22429. [PMID: 34585691 DOI: 10.1039/d1cp02759j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The indirect bandgap of two-dimensional GaN hinders its application in the optical field. Hydrogenation can convert the bandgap type of the GaN monolayer from an indirect to a direct one and also tune the bandgap size. The thermal transport, an important property in the application of two-dimensional materials, is also influenced by hydrogenation. By performing first-principles calculations and solving the phonon Boltzmann equation, we investigate the effect of hydrogenation on the thermal conductivity of the GaN monolayer. The results show that hydrogenation will slightly increase the thermal conductivity of the GaN monolayer from 70.62 Wm-1 K-1 to 76.23 Wm-1 K-1 at 300 K. The little effect of hydrogenation on thermal conductivity is mainly dominated by two competing factors: (1) the reduction of ZA mode lifetime due to the breaking of reflection symmetry after hydrogenation and (2) the increased contribution from TA and LA modes due to the reduction of anharmonic scattering caused by the enlarged phonon bandgap after hydrogenation. The results are compared with other two-dimensional materials with hexagonal monolayer structures.
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Affiliation(s)
- Xueru Cai
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
| | - Guoqing Sun
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
| | - Yaxin Xu
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
| | - Jinlong Ma
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
| | - Dongwei Xu
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
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13
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Davis ES, Voss G, Miesfeld JB, Zarate-Sanchez J, Voss SR, Glaser T. The rax homeobox gene is mutated in the eyeless axolotl, Ambystoma mexicanum. Dev Dyn 2021; 250:807-821. [PMID: 32864847 PMCID: PMC8907009 DOI: 10.1002/dvdy.246] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 08/11/2020] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Vertebrate eye formation requires coordinated inductive interactions between different embryonic tissue layers, first described in amphibians. A network of transcription factors and signaling molecules controls these steps, with mutations causing severe ocular, neuronal, and craniofacial defects. In eyeless mutant axolotls, eye morphogenesis arrests at the optic vesicle stage, before lens induction, and development of ventral forebrain structures is disrupted. RESULTS We identified a 5-bp deletion in the rax (retina and anterior neural fold homeobox) gene, which was tightly linked to the recessive eyeless (e) axolotl locus in an F2 cross. This frameshift mutation, in exon 2, truncates RAX protein within the homeodomain (P154fs35X). Quantitative RNA analysis shows that mutant and wild-type rax transcripts are equally abundant in E/e embryos. Translation appears to initiate from dual start codons, via leaky ribosome scanning, a conserved feature among gnathostome RAX proteins. Previous data show rax is expressed in the optic vesicle and diencephalon, deeply conserved among metazoans, and required for eye formation in other species. CONCLUSION The eyeless axolotl mutation is a null allele in the rax homeobox gene, with primary defects in neural ectoderm, including the retinal and hypothalamic primordia.
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Affiliation(s)
- Erik S. Davis
- Department of Cell Biology and Human Anatomy, University of California Davis School of Medicine, Davis, California
| | - Gareth Voss
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, and Ambystoma Genetic Stock Center, University of Kentucky, Lexington, Kentucky
| | - Joel B. Miesfeld
- Department of Cell Biology and Human Anatomy, University of California Davis School of Medicine, Davis, California
| | - Juan Zarate-Sanchez
- Department of Cell Biology and Human Anatomy, University of California Davis School of Medicine, Davis, California
- Davis Senior High School, Davis, California
| | - S. Randal Voss
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, and Ambystoma Genetic Stock Center, University of Kentucky, Lexington, Kentucky
| | - Tom Glaser
- Department of Cell Biology and Human Anatomy, University of California Davis School of Medicine, Davis, California
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14
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Tilley L, Papadopoulos SC, Pende M, Fei JF, Murawala P. The use of transgenics in the laboratory axolotl. Dev Dyn 2021; 251:942-956. [PMID: 33949035 DOI: 10.1002/dvdy.357] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 03/10/2021] [Accepted: 04/29/2021] [Indexed: 11/09/2022] Open
Abstract
The ability to generate transgenic animals sparked a wave of research committed to implementing such technology in a wide variety of model organisms. Building a solid base of ubiquitous and tissue-specific reporter lines has set the stage for later interrogations of individual cells or genetic elements. Compared to other widely used model organisms such as mice, zebrafish and fruit flies, there are only a few transgenic lines available in the laboratory axolotl (Ambystoma mexicanum), although their number is steadily expanding. In this review, we discuss a brief history of the transgenic methodologies in axolotl and their advantages and disadvantages. Next, we discuss available transgenic lines and insights we have been able to glean from them. Finally, we list challenges when developing transgenic axolotl, and where further work is needed in order to improve their standing as both a developmental and regenerative model.
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Affiliation(s)
- Lydia Tilley
- Mount Desert Island Biological Laboratory (MDIBL), Salisbury Cove, Maine, USA
| | - Sofia-Christina Papadopoulos
- Mount Desert Island Biological Laboratory (MDIBL), Salisbury Cove, Maine, USA.,Clinic for Kidney and Hypertension Diseases, Hannover Medical School, Hannover, Germany
| | - Marko Pende
- Mount Desert Island Biological Laboratory (MDIBL), Salisbury Cove, Maine, USA
| | - Ji-Feng Fei
- Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China.,Institute for Brain Research and Rehabilitation, South China Normal University, Guangzhou, China
| | - Prayag Murawala
- Mount Desert Island Biological Laboratory (MDIBL), Salisbury Cove, Maine, USA.,Clinic for Kidney and Hypertension Diseases, Hannover Medical School, Hannover, Germany
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15
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A complex genetic architecture in zebrafish relatives Danio quagga and D. kyathit underlies development of stripes and spots. PLoS Genet 2021; 17:e1009364. [PMID: 33901178 PMCID: PMC8102007 DOI: 10.1371/journal.pgen.1009364] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 05/06/2021] [Accepted: 04/08/2021] [Indexed: 02/07/2023] Open
Abstract
Vertebrate pigmentation is a fundamentally important, multifaceted phenotype. Zebrafish, Danio rerio, has been a valuable model for understanding genetics and development of pigment pattern formation due to its genetic and experimental tractability, advantages that are shared across several Danio species having a striking array of pigment patterns. Here, we use the sister species D. quagga and D. kyathit, with stripes and spots, respectively, to understand how natural genetic variation impacts phenotypes at cellular and organismal levels. We first show that D. quagga and D. kyathit phenotypes resemble those of wild-type D. rerio and several single locus mutants of D. rerio, respectively, in a morphospace defined by pattern variation along dorsoventral and anteroposterior axes. We then identify differences in patterning at the cellular level between D. quagga and D. kyathit by repeated daily imaging during pattern development and quantitative comparisons of adult phenotypes, revealing that patterns are similar initially but diverge ontogenetically. To assess the genetic architecture of these differences, we employ reduced-representation sequencing of second-generation hybrids. Despite the similarity of D. quagga to D. rerio, and D. kyathit to some D. rerio mutants, our analyses reveal a complex genetic basis for differences between D. quagga and D. kyathit, with several quantitative trait loci contributing to variation in overall pattern and cellular phenotypes, epistatic interactions between loci, and abundant segregating variation within species. Our findings provide a window into the evolutionary genetics of pattern-forming mechanisms in Danio and highlight the complexity of differences that can arise even between sister species. Further studies of natural genetic diversity underlying pattern variation in D. quagga and D. kyathit should provide insights complementary to those from zebrafish mutant phenotypes and more distant species comparisons. Pigment patterns of fishes are diverse and function in a wide range of behaviors. Common pattern themes include stripes and spots, exemplified by the closely related minnows Danio quagga and D. kyathit, respectively. We show that these patterns arise late in development owing to alterations in the development and arrangements of pigment cells. In the closely related model organism zebrafish (D. rerio) single genes can switch the pattern from stripes to spots. Yet, we show that pattern differences between D. quagga and D. kyathit have a more complex genetic basis, depending on multiple genes and interactions between these genes. Our findings illustrate the importance of characterizing naturally occurring genetic variants, in addition to laboratory induced mutations, for a more complete understanding of pigment pattern development and evolution.
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16
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Nowoshilow S, Fei JF, Voss SR, Tanaka EM, Murawala P. Gene and transgenics nomenclature for the laboratory axolotl-Ambystoma mexicanum. Dev Dyn 2021; 251:913-921. [PMID: 33896069 DOI: 10.1002/dvdy.351] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 04/19/2021] [Accepted: 04/19/2021] [Indexed: 01/10/2023] Open
Abstract
The laboratory axolotl (Ambystoma mexicanum) is widely used in biological research. Recent advancements in genetic and molecular toolkits are greatly accelerating the work using axolotl, especially in the area of tissue regeneration. At this juncture, there is a critical need to establish gene and transgenic nomenclature to ensure uniformity in axolotl research. Here, we propose guidelines for genetic nomenclature when working with the axolotl.
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Affiliation(s)
- Sergej Nowoshilow
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Ji-Feng Fei
- Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China.,Institute for Brain Research and Rehabilitation, South China Normal University, Guangzhou, China
| | - S Randal Voss
- Department of Neuroscience, University of Kentucky, Lexington, Kentucky, USA.,Ambystoma Genetic Stock Center, University of Kentucky, Lexington, Kentucky, USA.,Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky, USA
| | - Elly M Tanaka
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Prayag Murawala
- Mount Desert Island Biological laboratory (MDIBL), Salisbury Cove, USA.,Clinic for Kidney and Hypertension Diseases, Hannover Medical School, Hannover, Germany
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17
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Jiang C, Zhang Y, Wang F, Liu H. Toward Smart Information Processing with Synthetic DNA Molecules. Macromol Rapid Commun 2021; 42:e2100084. [PMID: 33864315 DOI: 10.1002/marc.202100084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/13/2021] [Indexed: 11/07/2022]
Abstract
DNA, a biological macromolecule, is a naturally evolved information material. From the structural point of view, an individual DNA strand can be considered as a chain of data with its bases working as single units. For decades, due to the high biochemical stability, large information storage capacity, and high recognition specificity, DNA has been recognized as an attractive material for information processing. Especially, the chemical synthesis strategies and DNA sequencing techniques have been rapidly developed recently, further enabling encoding information with synthetic DNA molecules. Herein, recent progresses are summarized on information processing based on synthetic DNA molecules from three aspects including information storage, computation, and encryption, and proposed the challenges and future development directions.
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Affiliation(s)
- Chu Jiang
- School of Chemical Science and Engineering, Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, Shanghai Research Institute for Intelligent Autonomous Systems, Tongji University, Shanghai, 200092, China
| | - Yinan Zhang
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and National Center for Translational Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
- Center for Molecular Design and Biomimetics, School of Molecular Sciences, The Biodesign Institute, Arizona State University, Tempe, AZ, 85287, USA
| | - Fei Wang
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and National Center for Translational Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Huajie Liu
- School of Chemical Science and Engineering, Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, Shanghai Research Institute for Intelligent Autonomous Systems, Tongji University, Shanghai, 200092, China
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18
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The giant axolotl genome uncovers the evolution, scaling, and transcriptional control of complex gene loci. Proc Natl Acad Sci U S A 2021; 118:2017176118. [PMID: 33827918 PMCID: PMC8053990 DOI: 10.1073/pnas.2017176118] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The axolotl is an important model organism because it is a tetrapod with a similar body plan to humans. Unlike humans, the axolotl regenerates limbs and other complex tissues. Therefore, the axolotl contributes to understanding evolution, development, and regeneration. With sophisticated tools for gene modification and tissue labeling, a fully assembled genome sequence was a sorely missing resource. Assembly was difficult because the genome size is 10× that of humans. Here, we use a cross-linking strategy called Hi-C to link together fragmented genome sequences to chromosome scale. We show that gene regulation occurs over very large genomic distances and that mitotic chromosomes are packaged efficiently. Vertebrates harbor recognizably orthologous gene complements but vary 100-fold in genome size. How chromosomal organization scales with genome expansion is unclear, and how acute changes in gene regulation, as during axolotl limb regeneration, occur in the context of a vast genome has remained a riddle. Here, we describe the chromosome-scale assembly of the giant, 32 Gb axolotl genome. Hi-C contact data revealed the scaling properties of interphase and mitotic chromosome organization. Analysis of the assembly yielded understanding of the evolution of large, syntenic multigene clusters, including the Major Histocompatibility Complex (MHC) and the functional regulatory landscape of the Fibroblast Growth Factor 8 (Axfgf8) region. The axolotl serves as a primary model for studying successful regeneration.
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19
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Dwaraka VB, Voss SR. Towards comparative analyses of salamander limb regeneration. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2021; 336:129-144. [PMID: 31584252 PMCID: PMC8908358 DOI: 10.1002/jez.b.22902] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 08/13/2019] [Accepted: 08/31/2019] [Indexed: 08/29/2023]
Abstract
Among tetrapods, only salamanders can regenerate their limbs and tails throughout life. This amazing regenerative ability has attracted the attention of scientists for hundreds of years. Now that large, salamander genomes are beginning to be sequenced for the first time, omics tools and approaches can be used to integrate new perspectives into the study of tissue regeneration. Here we argue the need to move beyond the primary salamander models to investigate regeneration in other species. Salamanders at first glance come across as a phylogenetically conservative group that has not diverged greatly from their ancestors. While salamanders do present ancestral characteristics of basal tetrapods, including the ability to regenerate limbs, data from fossils and data from studies that have tested for species differences suggest there may be considerable variation in how salamanders develop and regenerate their limbs. We review the case for expanded studies of salamander tissue regeneration and identify questions and approaches that are most likely to reveal commonalities and differences in regeneration among species. We also address challenges that confront such an initiative, some of which are regulatory and not scientific. The time is right to gain evolutionary perspective about mechanisms of tissue regeneration from comparative studies of salamander species.
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Affiliation(s)
- Varun B. Dwaraka
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, and Ambystoma Genetic Stock Center, University of Kentucky, Lexington, Kentucky
- Department of Biology, University of Kentucky, Lexington, Kentucky
| | - S. Randal Voss
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, and Ambystoma Genetic Stock Center, University of Kentucky, Lexington, Kentucky
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20
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Ullate-Agote A, Tzika AC. Characterization of the Leucistic Texas Rat Snake Pantherophis obsoletus. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.583136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Albinism and leucism are phenotypes resulting from impaired melanin pigmentation in the skin and skin appendages. However, melanin pigmentation of eyes remains unaffected in leucism. Here, using transmission electron microscopy, we show that the leucistic morph of the Texas rat snake (Pantherophis obsoletus lindheimeri) lacks both melanophores and xanthophores in its skin and exhibits a uniform ivory white color generated by iridophores and collagen fibers. In addition, we sequenced the full genome of a leucistic individual and obtained a highly-contiguous near-chromosome quality assembly of 1.69 Gb with an N50 of 14.5 Mb and an L50 of 29 sequences. Using a candidate-gene approach, we then identify in the leucistic genome a single-nucleotide deletion that generates a frameshift and a premature termination codon in the melanocyte inducing transcription factor (MITF) gene. This mutation shortens the translated protein from 574 to 286 amino acids, removing the helix-loop-helix DNA-binding domain that is highly conserved among vertebrates. Genotyping leucistic animals of independent lineages showed that not all leucistic individuals carry this single-nucleotide deletion. Subsequent gene expression analyses reveal that all leucistic individuals that we analyzed exhibit a significantly decreased expression of MITF. We thus suggest that mutations affecting the regulation and, in some cases, the coding sequence of MITF, the former probably predating the latter, could be associated with the leucistic phenotype in Texas rat snakes. MITF is involved in the development and survival of melanophores in vertebrates. In zebrafish, a classical model species for pigmentation that undergoes metamorphosis, larvae and adults of homozygous mitfa mutants lack melanophores, show an excess of iridophores and exhibit reduced yellow pigmentation. On the contrary, in the leucistic Texas rat snake, a non-metamorphic species, only iridophores persist. Our results suggest that fate determination of neural-crest derived melanophores and xanthophores, but not of iridophores, could require the expression of MITF during snake embryonic development.
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21
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Masselink W, Tanaka EM. Toward whole tissue imaging of axolotl regeneration. Dev Dyn 2020; 250:800-806. [PMID: 33336514 PMCID: PMC8247021 DOI: 10.1002/dvdy.282] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/14/2020] [Accepted: 12/14/2020] [Indexed: 12/26/2022] Open
Abstract
The axolotl is a highly regenerative organism and has been studied in laboratories for over 150 years. Despite a long‐standing fascination with regeneration in general and axolotl specifically, we are still scratching the surface trying to visualize and understand the complex cellular behavior that underlies axolotl regeneration. In this review, we will discuss the progress that has been made in visualizing these processes focusing on four major aspects: cell labeling approaches, the removal of pigmentation, reductionist approaches to perform live cell imaging, and finally recent developments applying tissue clearing strategies to visualize the processes that underly regeneration. We also provide several suggestions that the community could consider exploring, notably the generation of novel alleles that further reduce pigmentation as well as improvements in tissue clearing strategies. Historical perspective on axolotl imaging and lineage tracing Description of tissue clearing approaches Refractive index matching strategies Strategies to further reduce pigmentation in axolotl
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Affiliation(s)
- Wouter Masselink
- Research Institute of Molecular Pathology (IMP), Vienna BiocCenter (VBC), Vienna, Austria
| | - Elly M Tanaka
- Research Institute of Molecular Pathology (IMP), Vienna BiocCenter (VBC), Vienna, Austria
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22
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Melander SL, Mueller RL. Comprehensive Analysis of Salamander Hybridization Suggests a Consistent Relationship between Genetic Distance and Reproductive Isolation across Tetrapods. COPEIA 2020. [DOI: 10.1643/ch-19-319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Scott Lucas Melander
- Department of Biology, Colorado State University, 251 W Pitkin Street, Fort Collins, Colorado 80523; (SLM) ; and (RLM) . Send reprint requests to SLM
| | - Rachel Lockridge Mueller
- Department of Biology, Colorado State University, 251 W Pitkin Street, Fort Collins, Colorado 80523; (SLM) ; and (RLM) . Send reprint requests to SLM
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23
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Torres-Sánchez M. Variation under domestication in animal models: the case of the Mexican axolotl. BMC Genomics 2020; 21:827. [PMID: 33228551 PMCID: PMC7685626 DOI: 10.1186/s12864-020-07248-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 11/18/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Species adaptation to laboratory conditions is a special case of domestication that has modified model organisms phenotypically and genetically. The characterisation of these changes is crucial to understand how this variation can affect the outcome of biological experiments. Yet despite the wide use of laboratory animals in biological research, knowledge of the genetic diversity within and between different strains and populations of some animal models is still scarce. This is particularly the case of the Mexican axolotl, which has been bred in captivity since 1864. RESULTS Using gene expression data from nine different projects, nucleotide sequence variants were characterised, and distinctive genetic background of the experimental specimens was uncovered. This study provides a catalogue of thousands of nucleotide variants along predicted protein-coding genes, while identifying genome-wide differences between pigment phenotypes in laboratory populations. CONCLUSIONS Awareness of the genetic variation could guide a better experimental design while helping to develop molecular tools for monitoring genetic diversity and studying gene functions in laboratory axolotls. Overall, this study highlights the cross-taxa utility that transcriptomic data might have to assess the genetic variation of the experimental specimens, which might help to shorten the journey towards reproducible research.
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Affiliation(s)
- María Torres-Sánchez
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center & Ambystoma Genetic Stock Center, University of Kentucky, Lexington, KY, 40536, USA.
- Present address: Department of Biology, University of Florida, Gainesville, FL, 32611-8525, USA.
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24
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Timoshevskaya N, Voss SR, Labianca CN, High CR, Smith JJ. Large-scale variation in single nucleotide polymorphism density within the laboratory axolotl (Ambystoma mexicanum). Dev Dyn 2020; 250:822-837. [PMID: 33001517 DOI: 10.1002/dvdy.257] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/14/2020] [Accepted: 09/24/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Recent efforts to assemble and analyze the Ambystoma mexicanum genome have dramatically improved the potential to develop molecular tools and pursue genome-wide analyses of genetic variation. RESULTS To better resolve the distribution and origins of genetic variation with A mexicanum, we compared DNA sequence data for two laboratory A mexicanum and one A tigrinum to identify 702 million high confidence polymorphisms distributed across the 32 Gb genome. While the wild-caught A tigrinum was generally more polymorphic in a genome-wide sense, several multi-megabase regions were identified from A mexicanum genomes that were actually more polymorphic than A tigrinum. Analysis of polymorphism and repeat content reveals that these regions likely originated from the intentional hybridization of A mexicanum and A tigrinum that was used to introduce the albino mutation into laboratory stocks. CONCLUSIONS Our findings show that axolotl genomes are variable with respect to introgressed DNA from a highly polymorphic species. It seems likely that other divergent regions will be discovered with additional sequencing of A mexicanum. This has practical implications for designing molecular probes and suggests a need to study A mexicanum phenotypic variation and genome evolution across the tiger salamander clade.
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Affiliation(s)
| | - S Randal Voss
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky, USA.,Department of Neuroscience, University of Kentucky, Lexington, Kentucky, USA.,Ambystoma Genetic Stock Center, University of Kentucky, Lexington, Kentucky, USA
| | - Caitlin N Labianca
- Paul Laurence Dunbar High School, Lexington, Kentucky, USA.,Current Affiliation: Department of Biology, University of Rochester, Rochester, New York, USA
| | - Cassity R High
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky, USA.,Department of Neuroscience, University of Kentucky, Lexington, Kentucky, USA
| | - Jeramiah J Smith
- Department of Biology, University of Kentucky, Lexington, Kentucky, USA
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25
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Rozenblit F, Gollisch T. What the salamander eye has been telling the vision scientist's brain. Semin Cell Dev Biol 2020; 106:61-71. [PMID: 32359891 PMCID: PMC7493835 DOI: 10.1016/j.semcdb.2020.04.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/16/2020] [Accepted: 04/16/2020] [Indexed: 12/30/2022]
Abstract
Salamanders have been habitual residents of research laboratories for more than a century, and their history in science is tightly interwoven with vision research. Nevertheless, many vision scientists - even those working with salamanders - may be unaware of how much our knowledge about vision, and particularly the retina, has been shaped by studying salamanders. In this review, we take a tour through the salamander history in vision science, highlighting the main contributions of salamanders to our understanding of the vertebrate retina. We further point out specificities of the salamander visual system and discuss the perspectives of this animal system for future vision research.
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Affiliation(s)
- Fernando Rozenblit
- Department of Ophthalmology, University Medical Center Göttingen, 37073, Göttingen, Germany; Bernstein Center for Computational Neuroscience Göttingen, 37077, Göttingen, Germany
| | - Tim Gollisch
- Department of Ophthalmology, University Medical Center Göttingen, 37073, Göttingen, Germany; Bernstein Center for Computational Neuroscience Göttingen, 37077, Göttingen, Germany.
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26
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Square TA, Jandzik D, Massey JL, Romášek M, Stein HP, Hansen AW, Purkayastha A, Cattell MV, Medeiros DM. Evolution of the endothelin pathway drove neural crest cell diversification. Nature 2020; 585:563-568. [PMID: 32939088 DOI: 10.1038/s41586-020-2720-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 06/24/2020] [Indexed: 12/13/2022]
Abstract
Neural crest cells (NCCs) are migratory, multipotent embryonic cells that are unique to vertebrates and form an array of clade-defining adult features. The evolution of NCCs has been linked to various genomic events, including the evolution of new gene-regulatory networks1,2, the de novo evolution of genes3 and the proliferation of paralogous genes during genome-wide duplication events4. However, conclusive functional evidence linking new and/or duplicated genes to NCC evolution is lacking. Endothelin ligands (Edns) and endothelin receptors (Ednrs) are unique to vertebrates3,5,6, and regulate multiple aspects of NCC development in jawed vertebrates7-10. Here, to test whether the evolution of Edn signalling was a driver of NCC evolution, we used CRISPR-Cas9 mutagenesis11 to disrupt edn, ednr and dlx genes in the sea lamprey, Petromyzon marinus. Lampreys are jawless fishes that last shared a common ancestor with modern jawed vertebrates around 500 million years ago12. Thus, comparisons between lampreys and gnathostomes can identify deeply conserved and evolutionarily flexible features of vertebrate development. Using the frog Xenopus laevis to expand gnathostome phylogenetic representation and facilitate side-by-side analyses, we identify ancient and lineage-specific roles for Edn signalling. These findings suggest that Edn signalling was activated in NCCs before duplication of the vertebrate genome. Then, after one or more genome-wide duplications in the vertebrate stem, paralogous Edn pathways functionally diverged, resulting in NCC subpopulations with different Edn signalling requirements. We posit that this new developmental modularity facilitated the independent evolution of NCC derivatives in stem vertebrates. Consistent with this, differences in Edn pathway targets are associated with differences in the oropharyngeal skeleton and autonomic nervous system of lampreys and modern gnathostomes. In summary, our work provides functional genetic evidence linking the origin and duplication of new vertebrate genes with the stepwise evolution of a defining vertebrate novelty.
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Affiliation(s)
- Tyler A Square
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA. .,Department of Molecular and Cellular Biology, University of California, Berkeley, CA, USA.
| | - David Jandzik
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA. .,Department of Zoology, Comenius University in Bratislava, Bratislava, Slovakia. .,Department of Zoology, Charles University in Prague, Prague, Czech Republic.
| | - James L Massey
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
| | - Marek Romášek
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA.,Gymnázium Jiřího Wolkera, Prostějov, Czech Republic
| | - Haley P Stein
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
| | - Andrew W Hansen
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
| | - Amrita Purkayastha
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
| | - Maria V Cattell
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA.,Department of Biology, Metropolitan State University, Denver, CO, USA
| | - Daniel M Medeiros
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA.
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27
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Nowoshilow S, Tanaka EM. Introducing www.axolotl-omics.org - an integrated -omics data portal for the axolotl research community. Exp Cell Res 2020; 394:112143. [PMID: 32540400 DOI: 10.1016/j.yexcr.2020.112143] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/01/2020] [Accepted: 06/07/2020] [Indexed: 12/31/2022]
Abstract
Genomic resources are indispensable for biological investigations in model organisms. In recent years, a number of genomic resources including a full genome assembly, extensive transcriptomic data, as well as genome editing has been developed for the axolotl, a classical model organism for developmental, neurobiological and regeneration studies, making the axolotl a highly versatile system. Here we describe the Axolotl-omics website that allows rapid ortholog searches, and access to genome and transcriptomic resources.
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Affiliation(s)
- Sergej Nowoshilow
- Institute of Molecular Pathology Vienna Biocenter, Campus Vienna Biocenter 1, 1030, Vienna, Austria
| | - Elly M Tanaka
- Institute of Molecular Pathology Vienna Biocenter, Campus Vienna Biocenter 1, 1030, Vienna, Austria.
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28
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Burgon JD, Vieites DR, Jacobs A, Weidt SK, Gunter HM, Steinfartz S, Burgess K, Mable BK, Elmer KR. Functional colour genes and signals of selection in colour-polymorphic salamanders. Mol Ecol 2020; 29:1284-1299. [PMID: 32159878 DOI: 10.1111/mec.15411] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 03/06/2020] [Accepted: 03/09/2020] [Indexed: 12/11/2022]
Abstract
Coloration has been associated with multiple biologically relevant traits that drive adaptation and diversification in many taxa. However, despite the great diversity of colour patterns present in amphibians the underlying molecular basis is largely unknown. Here, we use insight from a highly colour-variable lineage of the European fire salamander (Salamandra salamandra bernardezi) to identify functional associations with striking variation in colour morph and pattern. The three focal colour morphs-ancestral black-yellow striped, fully yellow and fully brown-differed in pattern, visible coloration and cellular composition. From population genomic analyses of up to 4,702 loci, we found no correlations of neutral population genetic structure with colour morph. However, we identified 21 loci with genotype-phenotype associations, several of which relate to known colour genes. Furthermore, we inferred response to selection at up to 142 loci between the colour morphs, again including several that relate to coloration genes. By transcriptomic analysis across all different combinations, we found 196 differentially expressed genes between yellow, brown and black skin, 63 of which are candidate genes involved in animal coloration. The concordance across different statistical approaches and 'omic data sets provide several lines of evidence for loci linked to functional differences between colour morphs, including TYR, CAMK1 and PMEL. We found little association between colour morph and the metabolomic profile of its toxic compounds from the skin secretions. Our research suggests that current ecological and evolutionary hypotheses for the origins and maintenance of these striking colour morphs may need to be revisited.
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Affiliation(s)
- James D Burgon
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - David R Vieites
- Museo Nacional de Ciencias Naturales (MNCN), Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Arne Jacobs
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Stefan K Weidt
- Glasgow Polyomics, Wolfson Wohl Cancer Research Centre, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Helen M Gunter
- Edinburgh Genomics, King's Buildings, University of Edinburgh, Edinburgh, UK
| | - Sebastian Steinfartz
- Department of Evolutionary Biology, Unit Molecular Ecology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
| | - Karl Burgess
- Glasgow Polyomics, Wolfson Wohl Cancer Research Centre, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Barbara K Mable
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Kathryn R Elmer
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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29
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Platinum-group elements link the end-Triassic mass extinction and the Central Atlantic Magmatic Province. Sci Rep 2020; 10:3482. [PMID: 32103087 PMCID: PMC7044291 DOI: 10.1038/s41598-020-60483-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 02/07/2020] [Indexed: 11/14/2022] Open
Abstract
Elevated concentrations of iridium (Ir) and other platinum-group elements (PGE) have been reported in both terrestrial and marine sediments associated with the end-Triassic mass extinction (ETE) c. 201.5 million years ago. The source of the PGEs has been attributed to condensed vapor and melt from an extraterrestrial impactor or to volcanism. Here we report new PGE data for volcanic rocks of the Central Atlantic Magmatic Province (CAMP) in Morocco and show that their Pd/Ir, Pt/Ir and Pt/Rh ratios are similar to marine and terrestrial sediments at the ETE, and very different from potential impactors. Hence, we propose the PGEs provide a new temporal correlation of CAMP volcanism to the ETE, corroborating the view that mass extinctions may be caused by volcanism.
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30
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Peppou-Chapman S, Hong JK, Waterhouse A, Neto C. Life and death of liquid-infused surfaces: a review on the choice, analysis and fate of the infused liquid layer. Chem Soc Rev 2020; 49:3688-3715. [DOI: 10.1039/d0cs00036a] [Citation(s) in RCA: 109] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We review the rational choice, the analysis, the depletion and the properties imparted by the liquid layer in liquid-infused surfaces – a new class of low-adhesion surface.
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Affiliation(s)
- Sam Peppou-Chapman
- School of Chemistry
- The University of Sydney
- Australia
- The University of Sydney Nano Institute
- The University of Sydney
| | - Jun Ki Hong
- School of Chemistry
- The University of Sydney
- Australia
- The University of Sydney Nano Institute
- The University of Sydney
| | - Anna Waterhouse
- The University of Sydney Nano Institute
- The University of Sydney
- Australia
- Central Clinical School
- Faculty of Medicine and Health
| | - Chiara Neto
- School of Chemistry
- The University of Sydney
- Australia
- The University of Sydney Nano Institute
- The University of Sydney
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31
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Sibai M, Parlayan C, Tuğlu P, Öztürk G, Demircan T. Integrative Analysis of Axolotl Gene Expression Data from Regenerative and Wound Healing Limb Tissues. Sci Rep 2019; 9:20280. [PMID: 31889169 PMCID: PMC6937273 DOI: 10.1038/s41598-019-56829-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 12/09/2019] [Indexed: 01/08/2023] Open
Abstract
Axolotl (Ambystoma mexicanum) is a urodele amphibian endowed with remarkable regenerative capacities manifested in scarless wound healing and restoration of amputated limbs, which makes it a powerful experimental model for regenerative biology and medicine. Previous studies have utilized microarrays and RNA-Seq technologies for detecting differentially expressed (DE) genes in different phases of the axolotl limb regeneration. However, sufficient consistency may be lacking due to statistical limitations arising from intra-laboratory analyses. This study aims to bridge such gaps by performing an integrative analysis of publicly available microarray and RNA-Seq data from axolotl limb samples having comparable study designs using the “merging” method. A total of 351 genes were found DE in regenerative samples compared to the control in data of both technologies, showing an adjusted p-value < 0.01 and log fold change magnitudes >1. Downstream analyses illustrated consistent correlations of the directionality of DE genes within and between data of both technologies, as well as concordance with the literature on regeneration related biological processes. qRT-PCR analysis validated the observed expression level differences of five of the top DE genes. Future studies may benefit from the utilized concept and approach for enhanced statistical power and robust discovery of biomarkers of regeneration.
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Affiliation(s)
- Mustafa Sibai
- Graduate School of Engineering and Natural Sciences, Istanbul Medipol University, Istanbul, Turkey
| | - Cüneyd Parlayan
- Regenerative and Restorative Medicine Research Center, REMER, Istanbul Medipol University, Istanbul, Turkey. .,Department of Biomedical Engineering, Faculty of Engineering, İstanbul Medipol University, Istanbul, Turkey.
| | - Pelin Tuğlu
- Regenerative and Restorative Medicine Research Center, REMER, Istanbul Medipol University, Istanbul, Turkey
| | - Gürkan Öztürk
- Regenerative and Restorative Medicine Research Center, REMER, Istanbul Medipol University, Istanbul, Turkey.,Department of Physiology, International School of Medicine, İstanbul Medipol University, Istanbul, Turkey
| | - Turan Demircan
- Regenerative and Restorative Medicine Research Center, REMER, Istanbul Medipol University, Istanbul, Turkey. .,Department of Medical Biology, School of Medicine, Mugla Sitki Kocman University, Mugla, Turkey.
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32
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Patterson LB, Parichy DM. Zebrafish Pigment Pattern Formation: Insights into the Development and Evolution of Adult Form. Annu Rev Genet 2019; 53:505-530. [DOI: 10.1146/annurev-genet-112618-043741] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Vertebrate pigment patterns are diverse and fascinating adult traits that allow animals to recognize conspecifics, attract mates, and avoid predators. Pigment patterns in fish are among the most amenable traits for studying the cellular basis of adult form, as the cells that produce diverse patterns are readily visible in the skin during development. The genetic basis of pigment pattern development has been most studied in the zebrafish, Danio rerio. Zebrafish adults have alternating dark and light horizontal stripes, resulting from the precise arrangement of three main classes of pigment cells: black melanophores, yellow xanthophores, and iridescent iridophores. The coordination of adult pigment cell lineage specification and differentiation with specific cellular interactions and morphogenetic behaviors is necessary for stripe development. Besides providing a nice example of pattern formation responsible for an adult trait of zebrafish, stripe-forming mechanisms also provide a conceptual framework for posing testable hypotheses about pattern diversification more broadly. Here, we summarize what is known about lineages and molecular interactions required for pattern formation in zebrafish, we review some of what is known about pattern diversification in Danio, and we speculate on how patterns in more distant teleosts may have evolved to produce a stunningly diverse array of patterns in nature.
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Affiliation(s)
| | - David M. Parichy
- Department of Biology and Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22903, USA
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33
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Walheim J, Dillinger H, Kozerke S. Multipoint 5D flow cardiovascular magnetic resonance - accelerated cardiac- and respiratory-motion resolved mapping of mean and turbulent velocities. J Cardiovasc Magn Reson 2019; 21:42. [PMID: 31331353 PMCID: PMC6647085 DOI: 10.1186/s12968-019-0549-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 06/05/2019] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Volumetric quantification of mean and fluctuating velocity components of transient and turbulent flows promises a comprehensive characterization of valvular and aortic flow characteristics. Data acquisition using standard navigator-gated 4D Flow cardiovascular magnetic resonance (CMR) is time-consuming and actual scan times depend on the breathing pattern of the subject, limiting the applicability of the method in a clinical setting. We sought to develop a 5D Flow CMR framework which combines undersampled data acquisition including multipoint velocity encoding with low-rank image reconstruction to provide cardiac- and respiratory-motion resolved assessment of velocity maps and turbulent kinetic energy in fixed scan times. METHODS Data acquisition and data-driven motion state detection was performed using an undersampled Cartesian tiny Golden angle approach. Locally low-rank (LLR) reconstruction was implemented to exploit correlations among heart phases and respiratory motion states. To ensure accurate quantification of mean and turbulent velocities, a multipoint encoding scheme with two velocity encodings per direction was incorporated. Velocity-vector fields and turbulent kinetic energy (TKE) were obtained using a Bayesian approach maximizing the posterior probability given the measured data. The scan time of 5D Flow CMR was set to 4 min. 5D Flow CMR with acceleration factors of 19 .0 ± 0.21 (mean ± std) and velocity encodings (VENC) of 0.5 m/s and 1.5 m/s per axis was compared to navigator-gated 2x SENSE accelerated 4D Flow CMR with VENC = 1.5 m/s in 9 subjects. Peak velocities and peak flow were compared and magnitude images, velocity and TKE maps were assessed. RESULTS While net scan time of 5D Flow CMR was 4 min independent of individual breathing patterns, the scan times of the standard 4D Flow CMR protocol varied depending on the actual navigator gating efficiency and were 17.8 ± 3.9 min on average. Velocity vector fields derived from 5D Flow CMR in the end-expiratory state agreed well with data obtained from the navigated 4D protocol (normalized root-mean-square error 8.9 ± 2.1%). On average, peak velocities assessed with 5D Flow CMR were higher than for the 4D protocol (3.1 ± 4.4%). CONCLUSIONS Respiratory-motion resolved multipoint 5D Flow CMR allows mapping of mean and turbulent velocities in the aorta in 4 min.
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Affiliation(s)
- Jonas Walheim
- Institute for Biomedical Engineering, University and ETH Zurich, Gloriastrasse 35 8092, Zurich, Switzerland
| | - Hannes Dillinger
- Institute for Biomedical Engineering, University and ETH Zurich, Gloriastrasse 35 8092, Zurich, Switzerland
| | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich, Gloriastrasse 35 8092, Zurich, Switzerland
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34
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Smith JJ, Timoshevskaya N, Timoshevskiy VA, Keinath MC, Hardy D, Voss SR. A chromosome-scale assembly of the axolotl genome. Genome Res 2019; 29:317-324. [PMID: 30679309 PMCID: PMC6360810 DOI: 10.1101/gr.241901.118] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 11/26/2018] [Indexed: 01/14/2023]
Abstract
The axolotl (Ambystoma mexicanum) provides critical models for studying regeneration, evolution, and development. However, its large genome (∼32 Gb) presents a formidable barrier to genetic analyses. Recent efforts have yielded genome assemblies consisting of thousands of unordered scaffolds that resolve gene structures, but do not yet permit large-scale analyses of genome structure and function. We adapted an established mapping approach to leverage dense SNP typing information and for the first time assemble the axolotl genome into 14 chromosomes. Moreover, we used fluorescence in situ hybridization to verify the structure of these 14 scaffolds and assign each to its corresponding physical chromosome. This new assembly covers 27.3 Gb and encompasses 94% of annotated gene models on chromosomal scaffolds. We show the assembly's utility by resolving genome-wide orthologies between the axolotl and other vertebrates, identifying the footprints of historical introgression events that occurred during the development of axolotl genetic stocks, and precisely mapping several phenotypes including a large deletion underlying the cardiac mutant. This chromosome-scale assembly will greatly facilitate studies of the axolotl in biological research.
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Affiliation(s)
- Jeramiah J Smith
- Department of Biology, University of Kentucky, Lexington, Kentucky 40506, USA
| | | | | | - Melissa C Keinath
- Department of Biology, University of Kentucky, Lexington, Kentucky 40506, USA.,Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland 21218, USA
| | - Drew Hardy
- Department of Neuroscience, University of Kentucky, Lexington, Kentucky 40506, USA.,Ambystoma Genetic Stock Center, University of Kentucky, Lexington, Kentucky 40506, USA
| | - S Randal Voss
- Department of Neuroscience, University of Kentucky, Lexington, Kentucky 40506, USA.,Ambystoma Genetic Stock Center, University of Kentucky, Lexington, Kentucky 40506, USA.,Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky 40506, USA
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35
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Miniscule differences between sex chromosomes in the giant genome of a salamander. Sci Rep 2018; 8:17882. [PMID: 30552368 PMCID: PMC6294749 DOI: 10.1038/s41598-018-36209-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 11/12/2018] [Indexed: 11/08/2022] Open
Abstract
In the Mexican axolotl (Ambystoma mexicanum), sex is determined by a single Mendelian factor, yet its sex chromosomes do not exhibit morphological differentiation typical of many vertebrate taxa that possess a single sex-determining locus. As sex chromosomes are theorized to differentiate rapidly, species with undifferentiated sex chromosomes provide the opportunity to reconstruct early events in sex chromosome evolution. Whole genome sequencing of 48 salamanders, targeted chromosome sequencing and in situ hybridization were used to identify the homomorphic sex chromosome that carries an A. mexicanum sex-determining factor and sequences that are present only on the W chromosome. Altogether, these sequences cover ~300 kb of validated female-specific (W chromosome) sequence, representing ~1/100,000th of the 32 Gb genome. Notably, a recent duplication of ATRX, a gene associated with mammalian sex-determining pathways, is one of few functional (non-repetitive) genes identified among these W-specific sequences. This duplicated gene (ATRW) was used to develop highly predictive markers for diagnosing sex and represents a strong candidate for a recently-acquired sex determining locus (or sexually antagonistic gene) in A. mexicanum.
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36
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Fei JF, Lou WPK, Knapp D, Murawala P, Gerber T, Taniguchi Y, Nowoshilow S, Khattak S, Tanaka EM. Application and optimization of CRISPR-Cas9-mediated genome engineering in axolotl (Ambystoma mexicanum). Nat Protoc 2018; 13:2908-2943. [PMID: 30429597 DOI: 10.1038/s41596-018-0071-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Genomic manipulation is essential to the use of model organisms to understand development, regeneration and adult physiology. The axolotl (Ambystoma mexicanum), a type of salamander, exhibits an unparalleled regenerative capability in a spectrum of complex tissues and organs, and therefore serves as a powerful animal model for dissecting mechanisms of regeneration. We describe here an optimized stepwise protocol to create genetically modified axolotls using the CRISPR-Cas9 system. The protocol, which takes 7-8 weeks to complete, describes generation of targeted gene knockouts and knock-ins and includes site-specific integration of large targeting constructs. The direct use of purified CAS9-NLS (CAS9 containing a C-terminal nuclear localization signal) protein allows the prompt formation of guide RNA (gRNA)-CAS9-NLS ribonucleoprotein (RNP) complexes, which accelerates the creation of double-strand breaks (DSBs) at targeted genomic loci in single-cell-stage axolotl eggs. With this protocol, a substantial number of F0 individuals harboring a homozygous-type frameshift mutation can be obtained, allowing phenotype analysis in this generation. In the presence of targeting constructs, insertions of exogenous genes into targeted axolotl genomic loci can be achieved at efficiencies of up to 15% in a non-homologous end joining (NHEJ) manner. Our protocol bypasses the long generation time of axolotls and allows direct functional analysis in F0 genetically manipulated axolotls. This protocol can be potentially applied to other animal models, especially to organisms with a well-characterized transcriptome but lacking a well-characterized genome.
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Affiliation(s)
- Ji-Feng Fei
- Institute for Brain Research and Rehabilitation (IBRR), Guangdong Key Laboratory of Mental Health and Cognitive Science, South China Normal University, Guangzhou, China.
| | - Wilson Pak-Kin Lou
- School of Life Sciences, South China Normal University, Guangzhou, China
- The Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Dunja Knapp
- DFG Center for Regenerative Therapies, Dresden (CRTD), Technische Universität Dresden, Dresden, Germany
| | - Prayag Murawala
- The Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Tobias Gerber
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Yuka Taniguchi
- The Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Sergej Nowoshilow
- The Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Shahryar Khattak
- DFG Center for Regenerative Therapies, Dresden (CRTD), Technische Universität Dresden, Dresden, Germany
| | - Elly M Tanaka
- The Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
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37
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Iwanishi S, Zaitsu S, Shibata H, Nitasaka E. An albino mutant of the Japanese rat snake (Elaphe climacophora) carries a nonsense mutation in the tyrosinase gene. Genes Genet Syst 2018; 93:163-167. [PMID: 30158334 DOI: 10.1266/ggs.18-00021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The Japanese rat snake (Elaphe climacophora) is a common species in Japan and is widely distributed across the Japanese islands. An albino mutant of the Japanese rat snake ("pet trade" albino) has been bred and traded by hobbyists for around two decades because of its remarkable light-yellowish coloration with red eyes, attributable to a lack of melanin. Another albino Japanese rat snake mutant found in a natural population of the Japanese rat snake at high frequency in Iwakuni City, Yamaguchi Prefecture is known as "Iwakuni no Shirohebi". It has been conserved by the government as a natural monument. The Iwakuni albino also lacks melanin, having light-yellowish body coloration and red eyes. Albino mutants of several organisms have been studied, and mutation of the tyrosinase gene (TYR) is responsible for this phenotype. By determining the sequence of the TYR coding region of the pet trade albino, we identified a nonsense mutation in the second exon. Furthermore, RT-PCR revealed that TYR transcripts were not detected in this snake. These findings suggest that mutation of TYR is responsible for the albino phenotype of the pet trade line of the Japanese rat snake. However, the Iwakuni albino did not share this TYR mutation; thus, these two albino lines differ in their origins.
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Affiliation(s)
- Shuzo Iwanishi
- Graduate School of Systems Life Sciences, Kyushu University
| | - Shohei Zaitsu
- Graduate School of Systems Life Sciences, Kyushu University
| | - Hiroki Shibata
- Division of Genomics, Medical Institute of Bioregulation, Kyushu University
| | - Eiji Nitasaka
- Department of Biological Science, Faculty of Science, Kyushu University
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38
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Evolution of Endothelin signaling and diversification of adult pigment pattern in Danio fishes. PLoS Genet 2018; 14:e1007538. [PMID: 30226839 PMCID: PMC6161917 DOI: 10.1371/journal.pgen.1007538] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 09/28/2018] [Accepted: 08/13/2018] [Indexed: 12/13/2022] Open
Abstract
Fishes of the genus Danio exhibit diverse pigment patterns that serve as useful models for understanding the genes and cell behaviors underlying the evolution of adult form. Among these species, zebrafish D. rerio exhibit several dark stripes of melanophores with sparse iridophores that alternate with light interstripes of dense iridophores and xanthophores. By contrast, the closely related species D. nigrofasciatus has an attenuated pattern with fewer melanophores, stripes and interstripes. Here we demonstrate species differences in iridophore development that presage the fully formed patterns. Using genetic and transgenic approaches we identify the secreted peptide Endothelin-3 (Edn3)—a known melanogenic factor of tetrapods—as contributing to reduced iridophore proliferation and fewer stripes and interstripes in D. nigrofasciatus. We further show the locus encoding this factor is expressed at lower levels in D. nigrofasciatus owing to cis-regulatory differences between species. Finally, we show that functions of two paralogous loci encoding Edn3 have been partitioned between skin and non-skin iridophores. Our findings reveal genetic and cellular mechanisms contributing to pattern differences between these species and suggest a model for evolutionary changes in Edn3 requirements for pigment patterning and its diversification across vertebrates. Neural crest derived pigment cells generate the spectacular variation in skin pigment patterns among vertebrates. Mammals and birds have just a single skin pigment cell, the melanocyte, whereas ectothermic vertebrates have several pigment cells including melanophores, iridophores and xanthophores, that together organize into a diverse array of patterns. In the teleost zebrafish, Danio rerio, an adult pattern of stripes depends on interactions between pigment cell classes and between pigment cells and their tissue environment. The close relative D. nigrofasciatus has fewer stripes and prior analyses suggested a difference between these species that lies extrinsic to the pigment cells themselves. A candidate for mediating this difference is Endothelin-3 (Edn3), essential for melanocyte development in warm-blooded animals, and required by all three classes of pigment cells in an amphibian. We show that Edn3 specifically promotes iridophore development in Danio, and that differences in Edn3 expression contribute to differences in iridophore complements, and striping, between D. rerio and D. nigrofasciatus. Our study reveals a novel function for Edn3 and provides new insights into how changes in gene expression yield morphogenetic outcomes to effect diversification of adult form.
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39
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Affiliation(s)
- Alessio Zuliani
- Departamento de Química Orgánica; Universidad de Córdoba; Edificio Marie-Curie (C-3), Ctra Nnal IV Km 396 Cordoba Spain
| | - Francisco Ivars
- Abteilung Chemische Physik; Fritz-Haber-Institut der Max-Planck-Gesellschaft; Faradayweg 4-6 14195 Berlin Germany
| | - Rafael Luque
- Departamento de Química Orgánica; Universidad de Córdoba; Edificio Marie-Curie (C-3), Ctra Nnal IV Km 396 Cordoba Spain
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40
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Abstract
Humans and other mammals are limited in their natural abilities to regenerate lost body parts. By contrast, many salamanders are highly regenerative and can spontaneously replace lost limbs even as adults. Because salamander limbs are anatomically similar to human limbs, knowing how they regenerate should provide important clues for regenerative medicine. Although interest in understanding the mechanics of this process has never wavered, until recently researchers have been vexed by seemingly impenetrable logistics of working with these creatures at a molecular level. Chief among the problems has been the very large size of salamander genomes, and not a single salamander genome has been fully sequenced to date. Recently the enormous gap in sequence information has been bridged by approaches that leverage mRNA as the starting point. Together with functional experimentation, these data are rapidly enabling researchers to finally uncover the molecular mechanisms underpinning the astonishing biological process of limb regeneration.
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Affiliation(s)
- Brian J Haas
- Broad Institute of Massachusetts Institute of Technology(MIT) and Harvard, Klarman Cell Observatory, 415 Main Street, Cambridge, MA 02142, USA.
| | - Jessica L Whited
- Harvard Medical School, Harvard Stem Cell Institute, and Brigham and Women's Hospital Department of Orthopedic Surgery, 60 Fenwood Road, Boston, MA 02115, USA.
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