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Xi L, De Falco P, Barbieri E, Karunaratne A, Bentley L, Esapa CT, Terrill NJ, Brown SDM, Cox RD, Davis GR, Pugno NM, Thakker RV, Gupta HS. Bone matrix development in steroid-induced osteoporosis is associated with a consistently reduced fibrillar stiffness linked to altered bone mineral quality. Acta Biomater 2018; 76:295-307. [PMID: 29902593 PMCID: PMC6084282 DOI: 10.1016/j.actbio.2018.05.053] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 05/14/2018] [Accepted: 05/31/2018] [Indexed: 01/24/2023]
Abstract
Glucocorticoid-induced osteoporosis (GIOP) is a major secondary form of osteoporosis, with the fracture risk significantly elevated - at similar levels of bone mineral density - in patients taking glucocorticoids compared with non-users. The adverse bone structural changes at multiple hierarchical levels in GIOP, and their mechanistic consequences leading to reduced load-bearing capacity, are not clearly understood. Here we combine experimental X-ray nanoscale mechanical imaging with analytical modelling of the bone matrix mechanics to determine mechanisms causing bone material quality deterioration during development of GIOP. In situ synchrotron small-angle X-ray diffraction combined with tensile testing was used to measure nanoscale deformation mechanisms in a murine model of GIOP, due to a corticotrophin-releasing hormone promoter mutation, at multiple ages (8-, 12-, 24- and 36 weeks), complemented by quantitative micro-computed tomography and backscattered electron imaging to determine mineral concentrations. We develop a two-level hierarchical model of the bone matrix (mineralized fibril and lamella) to predict fibrillar mechanical response as a function of architectural parameters of the mineralized matrix. The fibrillar elastic modulus of GIOP-bone is lower than healthy bone throughout development, and nearly constant in time, in contrast to the progressively increasing stiffness in healthy bone. The lower mineral platelet aspect ratio value for GIOP compared to healthy bone in the multiscale model can explain the fibrillar deformation. Consistent with this result, independent measurement of mineral platelet lengths from wide-angle X-ray diffraction finds a shorter mineral platelet length in GIOP. Our results show how lowered mineralization combined with altered mineral nanostructure in GIOP leads to lowered mechanical competence. SIGNIFICANCE STATEMENT Increased fragility in musculoskeletal disorders like osteoporosis are believed to arise due to alterations in bone structure at multiple length-scales from the organ down to the supramolecular-level, where collagen molecules and elongated mineral nanoparticles form stiff fibrils. However, the nature of these molecular-level alterations are not known. Here we used X-ray scattering to determine both how bone fibrils deform in secondary osteoporosis, as well as how the fibril orientation and mineral nanoparticle structure changes. We found that osteoporotic fibrils become less stiff both because the mineral nanoparticles became shorter and less efficient at transferring load from collagen, and because the fibrils are more randomly oriented. These results will help in the design of new composite musculoskeletal implants for bone repair.
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Affiliation(s)
- L Xi
- School of Engineering and Material Sciences, Queen Mary University of London, London E1 4NS, UK; Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27607, USA
| | - P De Falco
- School of Engineering and Material Sciences, Queen Mary University of London, London E1 4NS, UK; Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, D-14424 Potsdam-Golm, Germany.
| | - E Barbieri
- School of Engineering and Material Sciences, Queen Mary University of London, London E1 4NS, UK; Department of Mathematical Science and Advanced Technology (MAT), Yokohama Institute for Earth Sciences (YES) 3173-25, Showa-machi, Kanazawa-ku, Yokohama-city, Japan.
| | - A Karunaratne
- Department of Mechanical Engineering, University of Moratuwa, Sri Lanka
| | - L Bentley
- MRC Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, OX11 0RD, UK.
| | - C T Esapa
- MRC Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, OX11 0RD, UK; Academic Endocrine Unit, Nuffield Department of Clinical Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Churchill Hospital, Headington, Oxford OX3 7JL, UK.
| | - N J Terrill
- Beamline I22, Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Chilton, Didcot, Oxfordshire OX11 0DE, UK.
| | - S D M Brown
- MRC Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, OX11 0RD, UK.
| | - R D Cox
- MRC Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, OX11 0RD, UK.
| | - G R Davis
- Queen Mary University of London, Barts and the London School of Medicine and Dentistry, Institute of Dentistry, E1 2AD, UK.
| | - N M Pugno
- Laboratory of Bio-Inspired & Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano, 77, 38123 Trento, Italy; School of Engineering and Material Sciences, Queen Mary University of London, London E1 4NS, UK; Ket Lab, Edoardo Amaldi Foundation, Italian Space Agency, Via del Politecnico snc, 00133 Rome, Italy.
| | - R V Thakker
- MRC Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, OX11 0RD, UK; Academic Endocrine Unit, Nuffield Department of Clinical Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Churchill Hospital, Headington, Oxford OX3 7JL, UK.
| | - H S Gupta
- School of Engineering and Material Sciences, Queen Mary University of London, London E1 4NS, UK.
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Karunaratne A, Xi L, Bentley L, Sykes D, Boyde A, Esapa CT, Terrill NJ, Brown SDM, Cox RD, Thakker RV, Gupta HS. Multiscale alterations in bone matrix quality increased fragility in steroid induced osteoporosis. Bone 2016; 84:15-24. [PMID: 26657825 PMCID: PMC4764652 DOI: 10.1016/j.bone.2015.11.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 10/30/2015] [Accepted: 11/27/2015] [Indexed: 12/31/2022]
Abstract
A serious adverse clinical effect of glucocorticoid steroid treatment is secondary osteoporosis, enhancing fracture risk in bone. This rapid increase in bone fracture risk is largely independent of bone loss (quantity), and must therefore arise from degradation of the quality of the bone matrix at the micro- and nanoscale. However, we lack an understanding of both the specific alterations in bone quality n steroid-induced osteoporosis as well as the mechanistic effects of these changes. Here we demonstrate alterations in the nanostructural parameters of the mineralized fibrillar collagen matrix, which affect bone quality, and develop a model linking these to increased fracture risk in glucocorticoid induced osteoporosis. Using a mouse model with an N-ethyl-N-nitrosourea (ENU)-induced corticotrophin releasing hormone promoter mutation (Crh(-120/+)) that developed hypercorticosteronaemia and osteoporosis, we utilized in situ mechanical testing with small angle X-ray diffraction, synchrotron micro-computed tomography and quantitative backscattered electron imaging to link altered nano- and microscale deformation mechanisms in the bone matrix to abnormal macroscopic mechanics. We measure the deformation of the mineralized collagen fibrils, and the nano-mechanical parameters including effective fibril modulus and fibril to tissue strain ratio. A significant reduction (51%) of fibril modulus was found in Crh(-120/+) mice. We also find a much larger fibril strain/tissue strain ratio in Crh(-120/+) mice (~1.5) compared to the wild-type mice (~0.5), indicative of a lowered mechanical competence at the nanoscale. Synchrotron microCT show a disruption of intracortical architecture, possibly linked to osteocytic osteolysis. These findings provide a clear quantitative demonstration of how bone quality changes increase macroscopic fragility in secondary osteoporosis.
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Affiliation(s)
- A Karunaratne
- Queen Mary University of London, School of Engineering and Material Science, Mile End Road, London E1 4NS, UK.
| | - L Xi
- Queen Mary University of London, School of Engineering and Material Science, Mile End Road, London E1 4NS, UK.
| | - L Bentley
- MRC Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, OX11 0RD, UK.
| | - D Sykes
- Core Research Laboratories, The Natural History Museum, London SW7 5BD, UK.
| | - A Boyde
- Queen Mary University of London, Barts and the London School of Medicine and Dentistry, Institute of Dentistry, E1 2AD, UK.
| | - C T Esapa
- MRC Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, OX11 0RD, UK; Academic Endocrine Unit, Nuffield Department of Clinical Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Churchill Hospital, Headington, Oxford OX3 7JL, UK.
| | - N J Terrill
- Diamond Light Source Ltd., Beamline I22, Diamond House, Harwell Science and Innovation Campus, Chilton, Didcot, Oxfordshire, OX11 0DE, UK; Department of Chemistry, University of Sheffield, Dainton Building, Brookhill, Sheffield S3 7HF, UK.
| | - S D M Brown
- MRC Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, OX11 0RD, UK.
| | - R D Cox
- MRC Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, OX11 0RD, UK.
| | - R V Thakker
- Academic Endocrine Unit, Nuffield Department of Clinical Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Churchill Hospital, Headington, Oxford OX3 7JL, UK.
| | - H S Gupta
- Queen Mary University of London, School of Engineering and Material Science, Mile End Road, London E1 4NS, UK.
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Karunaratne A, Boyde A, Esapa CT, Hiller J, Terrill NJ, Brown SDM, Cox RD, Thakker RV, Gupta HS. Symmetrically reduced stiffness and increased extensibility in compression and tension at the mineralized fibrillar level in rachitic bone. Bone 2013; 52:689-98. [PMID: 23128355 DOI: 10.1016/j.bone.2012.10.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 10/12/2012] [Accepted: 10/24/2012] [Indexed: 10/27/2022]
Abstract
In metabolic bone diseases, the alterations in fibrillar level bone-material quality affecting macroscopic mechanical competence are not well-understood quantitatively. Here, we quantify the fibrillar level deformation in cantilever bending in a mouse model for hereditary rickets (Hpr). Microfocus in-situ synchrotron small-angle X-ray scattering (SAXS) combined with cantilever bending was used to resolve nanoscale fibril strain in tensile- and compressive tissue regions separately, with quantitative backscattered scanning electron microscopy used to measure microscale mineralization. Tissue-level flexural moduli for Hpr mice were significantly (p<0.01) smaller compared to wild-type (~5 to 10-fold reduction). At the fibrillar level, the fibril moduli within the tensile and compressive zones were significantly (p<0.05) lower by ~3- to 5-fold in Hpr mice compared to wild-type mice. Hpr mice have a lower mineral content (24.2±2.1Cawt.% versus 27.4±3.3Ca wt.%) and its distribution was more heterogeneous compared to wild-type animals. However, the average effective fibril modulus did not differ significantly (p>0.05) over ages (4, 7 and 10weeks) between tensile and compressive zones. Our results indicate that incompletely mineralized fibrils in Hpr mice have greater deformability and lower moduli in both compression and tension, and those compressive and tensile zones have similar moduli at the fibrillar level.
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Affiliation(s)
- A Karunaratne
- School of Engineering and Material Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
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Abstract
ABSTRACTSeveral approaches for achieving reversible hydrogen uptake by carbon are considered, including intercalation, adsorption by a graphite surface, hydrogenation of fullerenes, and the filling of carbon nanotubes. Most scenarios suggest that it is difficult to achieve an atomic uptake [H/C] ratio exceeding unity. Evidence for H2 uptake by various carbon materials is reviewed.
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Mackenzie FE, Parker A, Parkinson NJ, Oliver PL, Brooker D, Underhill P, Lukashkina VA, Lukashkin AN, Holmes C, Brown SDM. Analysis of the mouse mutant Cloth-ears shows a role for the voltage-gated sodium channel Scn8a in peripheral neural hearing loss. Genes Brain Behav 2009; 8:699-713. [PMID: 19737145 PMCID: PMC2784214 DOI: 10.1111/j.1601-183x.2009.00514.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Deafness is the most common sensory disorder in humans and the aetiology of genetic deafness is complex. Mouse mutants have been crucial in identifying genes involved in hearing. However, many deafness genes remain unidentified. Using N-ethyl N−nitrosourea (ENU) mutagenesis to generate new mouse models of deafness, we identified a novel semi-dominant mouse mutant, Cloth-ears (Clth). Cloth-ears mice show reduced acoustic startle response and mild hearing loss from ∼30 days old. Auditory-evoked brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) analyses indicate that the peripheral neural auditory pathway is impaired in Cloth-ears mice, but that cochlear function is normal. In addition, both Clth/Clth and Clth/+ mice display paroxysmal tremor episodes with behavioural arrest. Clth/Clth mice also show a milder continuous tremor during movement and rest. Longitudinal phenotypic analysis showed that Clth/+ and Clth/Clth mice also have complex defects in behaviour, growth, neurological and motor function. Positional cloning of Cloth-ears identified a point mutation in the neuronal voltage-gated sodium channel α-subunit gene, Scn8a, causing an aspartic acid to valine (D981V) change six amino acids downstream of the sixth transmembrane segment of the second domain (D2S6). Complementation testing with a known Scn8a mouse mutant confirmed that this mutation is responsible for the Cloth-ears phenotype. Our findings suggest a novel role for Scn8a in peripheral neural hearing loss and paroxysmal motor dysfunction.
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Warren MV, Studley ML, Dubus P, Fiette L, Rozell B, Quintanilla-Martinez L, Raspa M, Breuer M, Song JY, Gates H, Brown SDM, Schofield PN. An impending crisis in the provision of histopathology expertise for mouse functional genomics. J Pathol 2009; 217:4-13. [DOI: 10.1002/path.2460] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abstract
The mouse is a key model organism for the study of mammalian genetics, development, physiology and biochemistry. The determination of the mouse genome sequence was therefore an early priority in the genome project. A draft sequence became available in 2002 and many chromosomes are now close to being finished. Comparative analysis of the mouse genome sequence with that of the human and other genomes has revealed a wealth of information on genome evolution in the mammalian lineage and assisted in the annotation of both genomes. With the availability of a well-annotated mouse genome sequence, mouse geneticists are now poised to undertake the challenge of generating mutations at every gene in the mouse genome. Systematic mutagenesis of the mouse genome will be an important step towards the first comprehensive functional annotation of a mammalian genome and the identification and characterisation of models for the study of human genetic disease.
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Kros CJ, Marcotti W, van Netten SM, Self TJ, Libby RT, Brown SDM, Richardson GP, Steel KP. Reduced climbing and increased slipping adaptation in cochlear hair cells of mice with Myo7a mutations. Nat Neurosci 2002; 5:41-7. [PMID: 11753415 DOI: 10.1038/nn784] [Citation(s) in RCA: 209] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mutations in Myo7a cause hereditary deafness in mice and humans. We describe the effects of two mutations, Myo7a(6J) and Myo7a(4626SB), on mechano-electrical transduction in cochlear hair cells. Both mutations result in two major functional abnormalities that would interfere with sound transduction. The hair bundles need to be displaced beyond their physiological operating range for mechanotransducer channels to open. Transducer currents also adapt more strongly than normal to excitatory stimuli. We conclude that myosin VIIA participates in anchoring and holding membrane-bound elements to the actin core of the stereocilium. Myosin VIIA is therefore required for the normal gating of transducer channels.
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MESH Headings
- Actins/metabolism
- Adaptation, Physiological
- Animals
- Cells, Cultured
- Cilia/physiology
- Cilia/ultrastructure
- Deafness/genetics
- Dihydrostreptomycin Sulfate/pharmacology
- Dyneins
- Electrophysiology
- Hair Cells, Auditory, Inner/drug effects
- Hair Cells, Auditory, Inner/physiology
- Hair Cells, Auditory, Inner/ultrastructure
- Hair Cells, Auditory, Outer/drug effects
- Hair Cells, Auditory, Outer/physiology
- Hair Cells, Auditory, Outer/ultrastructure
- Humans
- Ion Channel Gating
- Ion Channels/physiology
- Mice
- Molecular Motor Proteins/physiology
- Mutation
- Myosin VIIa
- Myosins/genetics
- Myosins/physiology
- Organ Culture Techniques
- Patch-Clamp Techniques
- Physical Stimulation
- Sound
- Vanadates/pharmacology
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Affiliation(s)
- C J Kros
- School of Biological Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK.
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Isaacs AM, Davies KE, Hunter AJ, Nolan PM, Vizor L, Peters J, Gale DG, Kelsell D, Latham ID, Chase JM, Fisher EMC, Bouzyk MM, Potter A, Masih M, Walsh FS, Sims MA, Doncaster KE, Parsons CA, Martin J, Brown SDM, Rastan S, Spurr NK, Gray IC. Identification Of Two New Pmp22 Mouse Mutants Using Large‐Scale Mutagenesis And A Novel Rapid Mapping Strategy. J Peripher Nerv Syst 2001. [DOI: 10.1046/j.1529-8027.2001.01008-19.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- AM Isaacs
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - KE Davies
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - AJ Hunter
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - PM Nolan
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - L Vizor
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - J Peters
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - DG Gale
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - Dp Kelsell
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - ID Latham
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - JM Chase
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - EMC Fisher
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - MM Bouzyk
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - A Potter
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - M Masih
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - FS Walsh
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - MA Sims
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - KE Doncaster
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - CA Parsons
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - J Martin
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - SDM Brown
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - S Rastan
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - NK Spurr
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
| | - IC Gray
- Human Molecular Genetics 9: 1865–1871, 2000. Reprinted with permission from Oxford University Press
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Brown SDM, Fisher E. EDITORIAL. Methods 1998; 14:105-6. [PMID: 9571069 DOI: 10.1006/meth.1997.0570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Copyright
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Silver LM, Nadeau JH, Brown SDM, Eppig JT, Peters J. Mammalian Genome, Incorporating Mouse Genome. Mamm Genome 1998; 9:1. [PMID: 9435276 DOI: 10.1007/s003359900669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Brown SDM. Towards an understanding of chromosome architecture Chromosome Banding(1990). By A. T. Sumner. Unwin Hyman, London. 434pp. £60. Bioessays 1992. [DOI: 10.1002/bies.950140514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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