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Martini A, Sahd L, Rücklin M, Huysseune A, Hall BK, Boglione C, Witten PE. Deformity or variation? Phenotypic diversity in the zebrafish vertebral column. J Anat 2023; 243:960-981. [PMID: 37424444 PMCID: PMC10641053 DOI: 10.1111/joa.13926] [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: 06/22/2022] [Revised: 06/14/2023] [Accepted: 06/23/2023] [Indexed: 07/11/2023] Open
Abstract
Vertebral bodies are composed of two types of metameric elements, centra and arches, each of which is considered as a developmental module. Most parts of the teleost vertebral column have a one-to-one relationship between centra and arches, although, in all teleosts, this one-to-one relationship is lost in the caudal fin endoskeleton. Deviation from the one-to-one relationship occurs in most vertebrates, related to changes in the number of vertebral centra or to a change in the number of arches. In zebrafish, deviations also occur predominantly in the caudal region of the vertebral column. In-depth phenotypic analysis of wild-type zebrafish was performed using whole-mount stained samples, histological analyses and synchrotron radiation X-ray tomographic microscopy 3D reconstructions. Three deviant centra phenotypes were observed: (i) fusion of two vertebral centra, (ii) wedge-shaped hemivertebrae and (iii) centra with reduced length. Neural and haemal arches and their spines displayed bilateral and unilateral variations that resemble vertebral column phenotypes of stem-ward actinopterygians or other gnathostomes as well as pathological conditions in extant species. Whether it is possible to distinguish variations from pathological alterations and whether alterations resemble ancestral conditions is discussed in the context of centra and arch variations in other vertebrate groups and basal actinopterygian species.
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Affiliation(s)
- Arianna Martini
- Laboratory of Experimental Ecology and Aquaculture, Department of Biology, University of Rome Tor Vergata, Rome, Italy
- Research Group Evolutionary Developmental Biology, Biology Department, Ghent University, Ghent, Belgium
- PhD Program in Evolutionary Biology and Ecology, Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - Lauren Sahd
- Research Group Evolutionary Developmental Biology, Biology Department, Ghent University, Ghent, Belgium
| | - Martin Rücklin
- Department of Vertebrate Evolution, Development and Ecology, Naturalis Biodiversity Center, Leiden, The Netherlands
| | - Ann Huysseune
- Research Group Evolutionary Developmental Biology, Biology Department, Ghent University, Ghent, Belgium
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Brian K Hall
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Clara Boglione
- Laboratory of Experimental Ecology and Aquaculture, Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - P Eckhard Witten
- Research Group Evolutionary Developmental Biology, Biology Department, Ghent University, Ghent, Belgium
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2
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Ben-Zvi I, Karasik D, Ackert-Bicknell CL. Zebrafish as a Model for Osteoporosis: Functional Validations of Genome-Wide Association Studies. Curr Osteoporos Rep 2023; 21:650-659. [PMID: 37971665 DOI: 10.1007/s11914-023-00831-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/02/2023] [Indexed: 11/19/2023]
Abstract
PURPOSE OF REVIEW GWAS, as a largely correlational analysis, requires in vitro or in vivo validation. Zebrafish (Danio rerio) have many advantages for studying the genetics of human diseases. Since gene editing in zebrafish has been highly valuable for studying embryonic skeletal developmental processes that are prenatally or perinatally lethal in mammalian models, we are reviewing pros and cons of this model. RECENT FINDINGS The true power for the use of zebrafish is the ease by which the genome can be edited, especially using the CRISPR/Cas9 system. Gene editing, followed by phenotyping, for complex traits such as BMD, is beneficial, but the major physiological differences between the fish and mammals must be considered. Like mammals, zebrafish do have main bone cells; thus, both in vivo stem cell analyses and in vivo imaging are doable. Yet, the "long" bones of fish are peculiar, and their bone cavities do not contain bone marrow. Partial duplication of the zebrafish genome should be taken into account. Overall, small fish toolkit can provide unmatched opportunities for genetic modifications and morphological investigation as a follow-up to human-first discovery.
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Affiliation(s)
- Inbar Ben-Zvi
- The Musculoskeletal Genetics Laboratory, The Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - David Karasik
- The Musculoskeletal Genetics Laboratory, The Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel.
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Adrião A, Mariano S, Mariano J, Gavaia PJ, Cancela ML, Vitorino M, Conceição N. mef2ca and mef2cb Double Mutant Zebrafish Show Altered Craniofacial Phenotype and Motor Behaviour. Biomolecules 2023; 13:biom13050805. [PMID: 37238675 DOI: 10.3390/biom13050805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 04/28/2023] [Accepted: 05/06/2023] [Indexed: 05/28/2023] Open
Abstract
The transcription factor MEF2C is crucial in neuronal, cardiac, bone and cartilage molecular processes, as well as for craniofacial development. MEF2C was associated with the human disease MRD20, whose patients show abnormal neuronal and craniofacial development. Zebrafish mef2ca;mef2cb double mutants were analysed for abnormalities in craniofacial and behaviour development through phenotypic analysis. Quantitative PCR was performed to investigate the expression levels of neuronal marker genes in mutant larvae. The motor behaviour was analysed by the swimming activity of 6 dpf larvae. We found that mef2ca;mef2cb double mutants display several abnormal phenotypes during early development, including those already described in zebrafish carrying mutations in each paralog, but also (i) a severe craniofacial phenotype (comprising both cartilaginous and dermal bone structures), (ii) developmental arrest due to the disruption of cardiac oedema and (iii) clear alterations in behaviour. We demonstrate that the defects observed in zebrafish mef2ca;mef2cb double mutants are similar to those previously described in MEF2C-null mice and MRD20 patients, confirming the usefulness of these mutant lines as a model for studies concerning MRD20 disease, the identification of new therapeutic targets and screening for possible rescue strategies.
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Affiliation(s)
- Andreia Adrião
- Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Sara Mariano
- Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - José Mariano
- Faculty of Sciences and Technology, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
- Center of Physics and Engineering of Advanced Materials (CeFEMA), IST, Universidade de Lisboa, Av. Rovisco Pais, 1096-001 Lisboa, Portugal
| | - Paulo J Gavaia
- Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
- Faculty of Medicine and Biomedical Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - M Leonor Cancela
- Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
- Faculty of Medicine and Biomedical Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
- Algarve Biomedical Center, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Marta Vitorino
- Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
- Faculty of Medicine and Biomedical Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
- Algarve Biomedical Center, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Natércia Conceição
- Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
- Faculty of Medicine and Biomedical Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
- Algarve Biomedical Center, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
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4
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Pleiotropic functions of chordin gene causing drastic morphological changes in ornamental goldfish. Sci Rep 2022; 12:19961. [PMID: 36402810 PMCID: PMC9675773 DOI: 10.1038/s41598-022-24444-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 11/15/2022] [Indexed: 11/21/2022] Open
Abstract
Breeders and fanciers have established many peculiar morphological phenotypes in ornamental goldfish. Among them, the twin-tail and dorsal-finless phenotypes have particularly intrigued early and recent researchers, as equivalent morphologies are extremely rare in nature. These two mutated phenotypes appeared almost simultaneously within a short time frame and were fixed in several strains. However, little is known about how these two different mutations could have co-occurred during such a short time period. Here, we demonstrate that the chordin gene, a key factor in dorsal-ventral patterning, is responsible not only for the twin-tail phenotype but also for the dorsal-finless phenotype. Our F2 backcrossing and functional analyses revealed that the penetrance/expressivity of the dorsal-finless phenotype can be suppressed by the wild-type allele of chdS. Based on these findings, we propose that chdSwt may have masked the expression of the dorsal-finless phenotype, acting as a capacitor buffering gene to allow accumulation of genetic mutations. Once this gene lost its original function in the twin-tail goldfish lineages, the dorsal-finless phenotype could be highly expressed. Thus, this study experimentally demonstrates that the rapid genetic fixation of morphological mutations during a short domestication time period may be related to the robustness of embryonic developmental mechanisms.
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Stenzel A, Mumme-Monheit A, Sucharov J, Walker M, Mitchell JM, Appel B, Nichols JT. Distinct and redundant roles for zebrafish her genes during mineralization and craniofacial patterning. Front Endocrinol (Lausanne) 2022; 13:1033843. [PMID: 36578958 PMCID: PMC9791542 DOI: 10.3389/fendo.2022.1033843] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/17/2022] [Indexed: 12/14/2022] Open
Abstract
The Notch pathway is a cell-cell communication system which is critical for many developmental processes, including craniofacial development. Notch receptor activation induces expression of several well-known canonical targets including those encoded by the hes and her genes in mammals and zebrafish, respectively. The function of these genes, individually and in combination, during craniofacial development is not well understood. Here, we used zebrafish genetics to investigate her9 and her6 gene function during craniofacial development. We found that her9 is required for osteoblasts to efficiently mineralize bone, while cartilage is largely unaffected. Strikingly, gene expression studies in her9 mutants indicate that although progenitor cells differentiate into osteoblasts at the appropriate time and place, they fail to efficiently lay down mineralized matrix. This mineralization role of her9 is likely independent of Notch activation. In contrast, her9 also functions redundantly with her6 downstream of Jagged1b-induced Notch activation during dorsoventral craniofacial patterning. These studies disentangle distinct and redundant her gene functions during craniofacial development, including an unexpected, Notch independent, requirement during bone mineralization.
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Affiliation(s)
- Amanda Stenzel
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Abigail Mumme-Monheit
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Juliana Sucharov
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Macie Walker
- Department of Pediatrics, Section of Developmental Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Jennyfer M. Mitchell
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Bruce Appel
- Department of Pediatrics, Section of Developmental Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - James T. Nichols
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
- *Correspondence: James T. Nichols,
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Kimmel CB, Wind AL, Oliva W, Ahlquist SD, Walker C, Dowd J, Blanco-Sánchez B, Titus TA, Batzel P, Talbot JC, Postlethwait JH, Nichols JT. Transgene-mediated skeletal phenotypic variation in zebrafish. JOURNAL OF FISH BIOLOGY 2021; 98:956-970. [PMID: 32112658 PMCID: PMC7483860 DOI: 10.1111/jfb.14300] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 01/13/2020] [Accepted: 02/25/2020] [Indexed: 05/03/2023]
Abstract
When considering relationships between genotype and phenotype we frequently ignore the fact that the genome of a typical animal, notably including that of a fish and a human, harbours a huge amount of foreign DNA. Such DNA, in the form of transposable elements, can affect genome function in a major way, and transgene biology needs to be included in our understanding of the genome. Here we examine an unexpected phenotypic effect of the chromosomally integrated transgene fli1a-F-hsp70l:Gal4VP16 that serves as a model for transgene function generally. We examine larval fras1 mutant zebrafish (Danio rerio). Gal4VP16 is a potent transcriptional activator that is already well known for toxicity and mediating unusual transcriptional effects. In the presence of the transgene, phenotypes in the neural crest-derived craniofacial skeleton, notably fusions and shape changes associated with loss of function fras1 mutations, are made more severe, as we quantify by scoring phenotypic penetrance, the fraction of mutants expressing the trait. A very interesting feature is that the enhancements are highly specific for fras1 mutant phenotypes, occurring in the apparent absence of more widespread changes. Except for the features due to the fras1 mutation, the transgene-bearing larvae appear generally healthy and to be developing normally. The transgene behaves as a genetic partial dominant: a single copy is sufficient for the enhancements, yet, for some traits, two copies may exert a stronger effect. We made new strains bearing independent insertions of the fli1a-F-hsp70l:Gal4VP16 transgene in new locations in the genome, and observed increased severities of the same phenotypes as observed for the original insertion. This finding suggests that sequences within the transgene, for example Gal4VP16, are responsible for the enhancements, rather than the effect on neighbouring host sequences (such as an insertional mutation). The specificity and biological action underlying the traits are subjects of considerable interest for further investigation, as we discuss. Our findings show that work with transgenes needs to be undertaken with caution and attention to detail.
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Affiliation(s)
| | | | - Whitney Oliva
- Institute of Neuroscience, University of Oregon, Eugene, OR, USA
| | | | - Charline Walker
- Institute of Neuroscience, University of Oregon, Eugene, OR, USA
| | - John Dowd
- Institute of Neuroscience, University of Oregon, Eugene, OR, USA
| | - Bernardo Blanco-Sánchez
- Institute of Neuroscience, University of Oregon, Eugene, OR, USA
- Current address: Laboratory of Embryology and Genetics of Congenital Malformations, INSERM UMR 1163, Institut Imagine, 75015 Paris, France
| | - Tom A. Titus
- Institute of Neuroscience, University of Oregon, Eugene, OR, USA
| | - Peter Batzel
- Institute of Neuroscience, University of Oregon, Eugene, OR, USA
| | - Jared C. Talbot
- School of Biology and Ecology, University of Maine, Orono, ME 04469, USA
| | | | - James T. Nichols
- Department of Craniofacial Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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7
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Mitchell JM, Sucharov J, Pulvino AT, Brooks EP, Gillen AE, Nichols JT. The alx3 gene shapes the zebrafish neurocranium by regulating frontonasal neural crest cell differentiation timing. Development 2021; 148:dev197483. [PMID: 33741714 PMCID: PMC8077506 DOI: 10.1242/dev.197483] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 03/12/2021] [Indexed: 12/30/2022]
Abstract
During craniofacial development, different populations of cartilage- and bone-forming cells develop in precise locations in the head. Most of these cells are derived from pluripotent cranial neural crest cells and differentiate with distinct developmental timing and cellular morphologies. The mechanisms that divide neural crest cells into discrete populations are not fully understood. Here, we use single-cell RNA sequencing to transcriptomically define different populations of cranial neural crest cells. We discovered that the gene family encoding the Alx transcription factors is enriched in the frontonasal population of neural crest cells. Genetic mutant analyses indicate that alx3 functions to regulate the distinct differentiation timing and cellular morphologies among frontonasal neural crest cell subpopulations. This study furthers our understanding of how genes controlling developmental timing shape craniofacial skeletal elements.
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Affiliation(s)
- Jennyfer M. Mitchell
- Department of Craniofacial Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Juliana Sucharov
- Department of Craniofacial Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Anthony T. Pulvino
- Department of Craniofacial Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Elliott P. Brooks
- Department of Craniofacial Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Austin E. Gillen
- RNA Bioscience Initiative, Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
- Department of Medicine, Division of Hematology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - James T. Nichols
- Department of Craniofacial Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- RNA Bioscience Initiative, Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
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8
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Mef2c factors are required for early but not late addition of cardiomyocytes to the ventricle. Dev Biol 2020; 470:95-107. [PMID: 33245870 PMCID: PMC7819464 DOI: 10.1016/j.ydbio.2020.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 11/15/2020] [Accepted: 11/20/2020] [Indexed: 12/15/2022]
Abstract
During heart formation, the heart grows and undergoes dramatic morphogenesis to achieve efficient embryonic function. Both in fish and amniotes, much of the growth occurring after initial heart tube formation arises from second heart field (SHF)-derived progenitor cell addition to the arterial pole, allowing chamber formation. In zebrafish, this process has been extensively studied during embryonic life, but it is unclear how larval cardiac growth occurs beyond 3 days post-fertilisation (dpf). By quantifying zebrafish myocardial growth using live imaging of GFP-labelled myocardium we show that the heart grows extensively between 3 and 5 dpf. Using methods to assess cell division, cellular development timing assay and Kaede photoconversion, we demonstrate that proliferation, CM addition, and hypertrophy contribute to ventricle growth. Mechanistically, we show that reduction in Mef2c activity (mef2ca+/-;mef2cb-/-), downstream or in parallel with Nkx2.5 and upstream of Ltbp3, prevents some CM addition and differentiation, resulting in a significantly smaller ventricle by 3 dpf. After 3 dpf, however, CM addition in mef2ca+/-;mef2cb-/- mutants recovers to a normal pace, and the heart size gap between mutants and their siblings diminishes into adulthood. Thus, as in mice, there is an early time window when SHF contribution to the myocardium is particularly sensitive to loss of Mef2c activity.
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9
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Tonelli F, Bek JW, Besio R, De Clercq A, Leoni L, Salmon P, Coucke PJ, Willaert A, Forlino A. Zebrafish: A Resourceful Vertebrate Model to Investigate Skeletal Disorders. Front Endocrinol (Lausanne) 2020; 11:489. [PMID: 32849280 PMCID: PMC7416647 DOI: 10.3389/fendo.2020.00489] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 06/22/2020] [Indexed: 12/11/2022] Open
Abstract
Animal models are essential tools for addressing fundamental scientific questions about skeletal diseases and for the development of new therapeutic approaches. Traditionally, mice have been the most common model organism in biomedical research, but their use is hampered by several limitations including complex generation, demanding investigation of early developmental stages, regulatory restrictions on breeding, and high maintenance cost. The zebrafish has been used as an efficient alternative vertebrate model for the study of human skeletal diseases, thanks to its easy genetic manipulation, high fecundity, external fertilization, transparency of rapidly developing embryos, and low maintenance cost. Furthermore, zebrafish share similar skeletal cells and ossification types with mammals. In the last decades, the use of both forward and new reverse genetics techniques has resulted in the generation of many mutant lines carrying skeletal phenotypes associated with human diseases. In addition, transgenic lines expressing fluorescent proteins under bone cell- or pathway- specific promoters enable in vivo imaging of differentiation and signaling at the cellular level. Despite the small size of the zebrafish, many traditional techniques for skeletal phenotyping, such as x-ray and microCT imaging and histological approaches, can be applied using the appropriate equipment and custom protocols. The ability of adult zebrafish to remodel skeletal tissues can be exploited as a unique tool to investigate bone formation and repair. Finally, the permeability of embryos to chemicals dissolved in water, together with the availability of large numbers of small-sized animals makes zebrafish a perfect model for high-throughput bone anabolic drug screening. This review aims to discuss the techniques that make zebrafish a powerful model to investigate the molecular and physiological basis of skeletal disorders.
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Affiliation(s)
- Francesca Tonelli
- Biochemistry Unit, Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Jan Willem Bek
- Department of Biomolecular Medicine, Center of Medical Genetics, Ghent University-University Hospital, Ghent, Belgium
| | - Roberta Besio
- Biochemistry Unit, Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Adelbert De Clercq
- Department of Biomolecular Medicine, Center of Medical Genetics, Ghent University-University Hospital, Ghent, Belgium
| | - Laura Leoni
- Biochemistry Unit, Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | | | - Paul J. Coucke
- Department of Biomolecular Medicine, Center of Medical Genetics, Ghent University-University Hospital, Ghent, Belgium
| | - Andy Willaert
- Department of Biomolecular Medicine, Center of Medical Genetics, Ghent University-University Hospital, Ghent, Belgium
| | - Antonella Forlino
- Biochemistry Unit, Department of Molecular Medicine, University of Pavia, Pavia, Italy
- *Correspondence: Antonella Forlino
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10
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Sucharov J, Ray K, Brooks EP, Nichols JT. Selective breeding modifies mef2ca mutant incomplete penetrance by tuning the opposing Notch pathway. PLoS Genet 2019; 15:e1008507. [PMID: 31790396 PMCID: PMC6907857 DOI: 10.1371/journal.pgen.1008507] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 12/12/2019] [Accepted: 11/04/2019] [Indexed: 02/07/2023] Open
Abstract
Deleterious genetic mutations allow developmental biologists to understand how genes control development. However, not all loss of function genetic mutants develop phenotypic changes. Many deleterious mutations only produce a phenotype in a subset of mutant individuals, a phenomenon known as incomplete penetrance. Incomplete penetrance can confound analyses of gene function and our understanding of this widespread phenomenon remains inadequate. To better understand what controls penetrance, we capitalized on the zebrafish mef2ca mutant which produces craniofacial phenotypes with variable penetrance. Starting with a characterized mef2ca loss of function mutant allele, we used classical selective breeding methods to generate zebrafish strains in which mutant-associated phenotypes consistently appear with low or high penetrance. Strikingly, our selective breeding for low penetrance converted the mef2ca mutant allele behavior from homozygous lethal to homozygous viable. Meanwhile, selective breeding for high penetrance converted the mef2ca mutant allele from fully recessive to partially dominant. Comparing the selectively-bred low- and high-penetrance strains revealed that the strains initially respond similarly to the mutation, but then gene expression differences between strains emerge during development. Thus, altered temporal genetic circuitry can manifest through selective pressure to modify mutant penetrance. Specifically, we demonstrate differences in Notch signaling between strains, and further show that experimental manipulation of the Notch pathway phenocopies penetrance changes occurring through selective breeding. This study provides evidence that penetrance is inherited as a liability-threshold trait. Our finding that vertebrate animals can overcome a deleterious mutation by tuning genetic circuitry complements other reported mechanisms of overcoming deleterious mutations such as transcriptional adaptation of compensatory genes, alternative mRNA splicing, and maternal deposition of wild-type transcripts, which are not observed in our system. The selective breeding approach and the resultant genetic circuitry change we uncovered advances and expands our current understanding of genetic and developmental resilience. Some deleterious gene mutations only affect a subset of genetically mutant animals. This widespread phenomenon, known as mutant incomplete penetrance, complicates discovery of causative gene mutations in both model organisms and human disease. This study utilized the zebrafish mef2ca transcription factor mutant that produces craniofacial skeleton defects with incomplete penetrance. Selectively breeding zebrafish families for low- or high-penetrance mutants for many generations created different zebrafish strains with consistently low or high penetrance. Comparing these strains allowed us to gain insight into the mechanisms that control penetrance. Specifically, genes under the control of mef2ca are initially similarly expressed between the two strains, but differences between strains emerge during development. We found that genetic manipulation of these downstream genes mimics the effects of our selective breeding. Thus, selective breeding for penetrance can change the genetic circuitry downstream of the mutated gene. We propose that small differences in gene circuitry between individuals is one mechanism underlying susceptibility or resilience to genetic mutations.
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Affiliation(s)
- Juliana Sucharov
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Kuval Ray
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Elliott P. Brooks
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - James T. Nichols
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- * E-mail:
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11
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Initiation and early growth of the skull vault in zebrafish. Mech Dev 2019; 160:103578. [PMID: 31644945 DOI: 10.1016/j.mod.2019.103578] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 09/24/2019] [Accepted: 10/03/2019] [Indexed: 02/06/2023]
Abstract
The zebrafish offers powerful advantages as a model system for examining the growth of the skull vault and the formation of cranial sutures. The zebrafish is well suited for large-scale genetic screens, available in large numbers, and continual advances in genetic engineering facilitate precise modeling of human genetic disorders. Most importantly, zebrafish are continuously accessible for imaging during critical periods of skull formation when both mouse and chick are physically inaccessible. To establish a foundation of information on the dynamics of skull formation, we performed a longitudinal study based on confocal microscopy of individual live transgenic zebrafish. Discrete events occur at stereotyped stages in overall growth, with little variation in timing among individuals. The frontal and parietal bones initiate as small clusters of cells closely associated with cartilage around the perimeter of the skull, prior to metamorphosis and the transition to juvenile fish. Over a period of ~30 days, the frontal and parietal bones grow towards the apex of the skull and meet to begin suture formation. To aid in visualization, we have generated interactive three-dimensional models based on the imaging data, with annotated cartilage and bone elements. We propose a framework to conceptualize development of bones of the skull vault in three phases: initiation in close association with cartilage; rapid planar growth towards the apex of the skull; and finally overlapping to form sutures. Our data provide an important framework for comparing the stages and timing of skull development across model organisms, and also a baseline for the examination of zebrafish mutants affecting skull development. To facilitate these comparative analyses, the raw imaging data and the models are available as an online atlas through the FaceBase consortium (facebase.org).
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12
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Feeley BE, Bhardwaj V, McLaughlin PT, Diggs S, Blaha GM, Higgs PI. An amino-terminal threonine/serine motif is necessary for activity of the Crp/Fnr homolog, MrpC and for Myxococcus xanthus developmental robustness. Mol Microbiol 2019; 112:1531-1551. [PMID: 31449700 DOI: 10.1111/mmi.14378] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2019] [Indexed: 11/30/2022]
Abstract
The Crp/Fnr family of transcriptional regulators play central roles in transcriptional control of diverse physiological responses, and are activated by a surprising diversity of mechanisms. MrpC is a Crp/Fnr homolog that controls the Myxococcus xanthus developmental program. A long-standing model proposed that MrpC activity is controlled by the Pkn8/Pkn14 serine/threonine kinase cascade, which phosphorylates MrpC on threonine residue(s) located in its extreme amino-terminus. In this study, we demonstrate that a stretch of consecutive threonine and serine residues, T21 T22 S23 S24, is necessary for MrpC activity by promoting efficient DNA binding. Mass spectrometry analysis indicated the TTSS motif is not directly phosphorylated by Pkn14 in vitro but is necessary for efficient Pkn14-dependent phosphorylation on several residues in the remainder of the protein. In an important correction to a long-standing model, we show Pkn8 and Pkn14 kinase activities do not play obvious roles in controlling MrpC activity in wild-type M. xanthus under laboratory conditions. Instead, we propose Pkn14 modulates MrpC DNA binding in response to unknown environmental conditions. Interestingly, substitutions in the TTSS motif caused developmental defects that varied between biological replicates, revealing that MrpC plays a role in promoting a robust developmental phenotype.
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Affiliation(s)
- Brooke E Feeley
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - Vidhi Bhardwaj
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Hesse, Germany
| | | | - Stephen Diggs
- Department of Biochemistry, University of California, Riverside, Riverside, CA, USA
| | - Gregor M Blaha
- Department of Biochemistry, University of California, Riverside, Riverside, CA, USA
| | - Penelope I Higgs
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
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13
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Bergen DJM, Kague E, Hammond CL. Zebrafish as an Emerging Model for Osteoporosis: A Primary Testing Platform for Screening New Osteo-Active Compounds. Front Endocrinol (Lausanne) 2019; 10:6. [PMID: 30761080 PMCID: PMC6361756 DOI: 10.3389/fendo.2019.00006] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 01/09/2019] [Indexed: 12/16/2022] Open
Abstract
Osteoporosis is metabolic bone disease caused by an altered balance between bone anabolism and catabolism. This dysregulated balance is responsible for fragile bones that fracture easily after minor falls. With an aging population, the incidence is rising and as yet pharmaceutical options to restore this imbalance is limited, especially stimulating osteoblast bone-building activity. Excitingly, output from large genetic studies on people with high bone mass (HBM) cases and genome wide association studies (GWAS) on the population, yielded new insights into pathways containing osteo-anabolic players that have potential for drug target development. However, a bottleneck in development of new treatments targeting these putative osteo-anabolic genes is the lack of animal models for rapid and affordable testing to generate functional data and that simultaneously can be used as a compound testing platform. Zebrafish, a small teleost fish, are increasingly used in functional genomics and drug screening assays which resulted in new treatments in the clinic for other diseases. In this review we outline the zebrafish as a powerful model for osteoporosis research to validate potential therapeutic candidates, describe the tools and assays that can be used to study bone homeostasis, and affordable (semi-)high-throughput compound testing.
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Affiliation(s)
- Dylan J. M. Bergen
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol, United Kingdom
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical School, Southmead Hospital, University of Bristol, Bristol, United Kingdom
| | - Erika Kague
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol, United Kingdom
| | - Chrissy L. Hammond
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol, United Kingdom
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14
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DeLaurier A. Evolution and development of the fish jaw skeleton. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2018; 8:e337. [PMID: 30378758 DOI: 10.1002/wdev.337] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 09/25/2018] [Accepted: 09/27/2018] [Indexed: 12/18/2022]
Abstract
The evolution of the jaw represents a key innovation in driving the diversification of vertebrate body plans and behavior. The pharyngeal apparatus originated as gill bars separated by slits in chordate ancestors to vertebrates. Later, with the acquisition of neural crest, pharyngeal arches gave rise to branchial basket cartilages in jawless vertebrates (agnathans), and later bone and cartilage of the jaw, jaw support, and gills of jawed vertebrates (gnathostomes). Major events in the evolution of jaw structure from agnathans to gnathostomes include axial regionalization of pharyngeal elements and formation of a jaw joint. Hox genes specify the anterior-posterior identity of arches, and edn1, dlx, hand2, Jag1b-Notch2 signaling, and Nr2f factors specify dorsal-ventral identity. The formation of a jaw joint, an important step in the transition from an un-jointed pharynx in agnathans to a hinged jaw in gnathostomes involves interaction between nkx3.2, hand2, and barx1 factors. Major events in jaw patterning between fishes and reptiles include changes to elements of the second pharyngeal arch, including a loss of opercular and branchiostegal ray bones and transformation of the hyomandibula into the stapes. Further changes occurred between reptiles and mammals, including the transformation of the articular and quadrate elements of the jaw joint into the malleus and incus of the middle ear. Fossils of transitional jaw phenotypes can be analyzed from a developmental perspective, and there exists potential to use genetic manipulation techniques in extant taxa to test hypotheses about the evolution of jaw patterning in ancient vertebrates. This article is categorized under: Comparative Development and Evolution > Evolutionary Novelties Early Embryonic Development > Development to the Basic Body Plan Comparative Development and Evolution > Body Plan Evolution.
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Affiliation(s)
- April DeLaurier
- Department of Biology and Geology, University of South Carolina Aiken, Aiken, South Carolina
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15
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Hallgrimsson B, Green RM, Katz DC, Fish JL, Bernier FP, Roseman CC, Young NM, Cheverud JM, Marcucio RS. The developmental-genetics of canalization. Semin Cell Dev Biol 2018; 88:67-79. [PMID: 29782925 DOI: 10.1016/j.semcdb.2018.05.019] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 05/16/2018] [Accepted: 05/17/2018] [Indexed: 10/16/2022]
Abstract
Canalization, or robustness to genetic or environmental perturbations, is fundamental to complex organisms. While there is strong evidence for canalization as an evolved property that varies among genotypes, the developmental and genetic mechanisms that produce this phenomenon are very poorly understood. For evolutionary biology, understanding how canalization arises is important because, by modulating the phenotypic variation that arises in response to genetic differences, canalization is a determinant of evolvability. For genetics of disease in humans and for economically important traits in agriculture, this subject is important because canalization is a potentially significant cause of missing heritability that confounds genomic prediction of phenotypes. We review the major lines of thought on the developmental-genetic basis for canalization. These fall into two groups. One proposes specific evolved molecular mechanisms while the other deals with robustness or canalization as a more general feature of development. These explanations for canalization are not mutually exclusive and they overlap in several ways. General explanations for canalization are more likely to involve emergent features of development than specific molecular mechanisms. Disentangling these explanations is also complicated by differences in perspectives between genetics and developmental biology. Understanding canalization at a mechanistic level will require conceptual and methodological approaches that integrate quantitative genetics and developmental biology.
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Affiliation(s)
- Benedikt Hallgrimsson
- Dept. of Cell Biology & Anatomy, Alberta Children's Hospital Research Institute and McCaig Bone and Joint Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada.
| | - Rebecca M Green
- Dept. of Cell Biology & Anatomy, Alberta Children's Hospital Research Institute and McCaig Bone and Joint Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - David C Katz
- Dept. of Cell Biology & Anatomy, Alberta Children's Hospital Research Institute and McCaig Bone and Joint Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Jennifer L Fish
- Dept. of Biological Sciences, University of Massachusetts Lowell, Lowell, MA, 01854, USA
| | - Francois P Bernier
- Dept of Medical Genetics, Alberta Children's Hospital Research Institute Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Charles C Roseman
- Dept. of Animal Biology, University of Illinois Urbana Champaign, Urbana, IL, 61801, USA
| | - Nathan M Young
- Dept. of Orthopaedic Surgery, School of Medicine, University of California San Francisco, San Francisco, CA, 94110, USA
| | - James M Cheverud
- Dept. of Biology, Loyola University Chicago, Chicago, IL, 60660, USA
| | - Ralph S Marcucio
- Dept. of Orthopaedic Surgery, School of Medicine, University of California San Francisco, San Francisco, CA, 94110, USA.
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16
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Kimmel CB, Small CM, Knope ML. A rich diversity of opercle bone shape among teleost fishes. PLoS One 2017; 12:e0188888. [PMID: 29281662 PMCID: PMC5744915 DOI: 10.1371/journal.pone.0188888] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 11/14/2017] [Indexed: 11/18/2022] Open
Abstract
The opercle is a prominent craniofacial bone supporting the gill cover in all bony fish and has been the subject of morphological, developmental, and genetic investigation. We surveyed the shapes of this bone among 110 families spanning the teleost tree and examined its pattern of occupancy in a principal component-based morphospace. Contrasting with expectations from the literature that suggest the local morphospace would be only sparsely occupied, we find primarily dense, broad filling of the morphological landscape, indicating rich diversity. Phylomorphospace plots suggest that dynamic evolution underlies the observed spatial patterning. Evolutionary transits through the morphospaces are sometimes long, and occur in a variety of directions. The trajectories seem to represent both evolutionary divergences and convergences, the latter supported by convevol analysis. We suggest that that this pattern of occupancy reflects the various adaptations of different groups of fishes, seemingly paralleling their diverse marine and freshwater ecologies and life histories. Opercle shape evolution within the acanthomorphs, spiny ray-finned fishes, appears to have been especially dynamic.
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Affiliation(s)
- Charles B. Kimmel
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, United States of America
| | - Clayton M. Small
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, United States of America
| | - Matthew L. Knope
- Department of Biology, University of Hawaii at Hilo, Hilo, Hawaii, United States of America
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17
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Lazić MM, Rödder D, Kaliontzopoulou A. The ontogeny of developmental buffering in lizard head shape. Evol Dev 2017; 19:244-252. [PMID: 28925092 DOI: 10.1111/ede.12238] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Canalization and developmental stability (DS) are important organismal properties involved in determining the level of phenotypic variation. Ontogenetic patterns of phenotypic variance components can shed light on the mechanistic basis of developmental buffering (DB). Here, we analyze how individual FA and among-individual variation in head shape change in ontogenetic series of three lizard species raised in laboratory. The degree of asymmetry increased slightly with size, suggesting that developmental mechanisms hypothesized to correct for deviations either do not exist, or that their efficiency is truncated with increasing size. Alternatively, they may need the disturbance as a trigger. The relationship between asymmetry and age was complex, with asymmetry being stable across the age range in two species but increased with age in the third. Lack of congruence in ontogenetic patterns of asymmetry might be due to intrinsic differences in buffering mechanisms or a result of species-specific growth patterns. Head shape was shown to be equally canalized across both size and age range in all species, probably as a result of a balance between the buffering mechanisms and mechanisms generating variance. The patterns of symmetric and asymmetric head shape variation were highly correlated across species meaning that DS and canalization may rely on similar mechanisms.
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Affiliation(s)
- Marko M Lazić
- Zoologisches Forschungsmuseum Alexander Koenig, Bonn, Germany
| | - Dennis Rödder
- Zoologisches Forschungsmuseum Alexander Koenig, Bonn, Germany
| | - Antigoni Kaliontzopoulou
- CIBIO Research Centre in Biodiversity and Genetic Resources, InBIO, University of Porto, Vairão, Portugal
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18
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Brooks EP, Nichols JT. Shifting Zebrafish Lethal Skeletal Mutant Penetrance by Progeny Testing. J Vis Exp 2017. [PMID: 28892034 DOI: 10.3791/56200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Zebrafish mutant phenotypes are often incompletely penetrant, only manifesting in some mutants. Interesting phenotypes that inconsistently appear can be difficult to study, and can lead to confounding results. The protocol described here is a straightforward breeding paradigm to increase and decrease penetrance in lethal zebrafish skeletal mutants. Because lethal mutants cannot be selectively bred directly, the classic selective breeding strategy of progeny testing is employed. This method also includes protocols for Kompetitive Allele Specific PCR (KASP) genotyping zebrafish and staining larval zebrafish cartilage and bone. Applying the husbandry strategy described here can increase the penetrance of an interesting skeletal phenotype enabling more reproducible results in downstream applications. In addition, decreasing the mutant penetrance through this selective breeding strategy can reveal the developmental processes that most crucially require the function of the mutated gene. While the skeleton is specifically considered here, we propose that this methodology will be useful for all zebrafish mutant lines.
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Affiliation(s)
- Elliott P Brooks
- Department of Craniofacial Biology, University of Colorado Anschutz Medical Campus
| | - James T Nichols
- Department of Craniofacial Biology, University of Colorado Anschutz Medical Campus;
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19
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Askary A, Xu P, Barske L, Bay M, Bump P, Balczerski B, Bonaguidi MA, Crump JG. Genome-wide analysis of facial skeletal regionalization in zebrafish. Development 2017; 144:2994-3005. [PMID: 28705894 DOI: 10.1242/dev.151712] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 07/10/2017] [Indexed: 12/16/2022]
Abstract
Patterning of the facial skeleton involves the precise deployment of thousands of genes in distinct regions of the pharyngeal arches. Despite the significance for craniofacial development, how genetic programs drive this regionalization remains incompletely understood. Here we use combinatorial labeling of zebrafish cranial neural crest-derived cells (CNCCs) to define global gene expression along the dorsoventral axis of the developing arches. Intersection of region-specific transcriptomes with expression changes in response to signaling perturbations demonstrates complex roles for Endothelin 1 (Edn1) signaling in the intermediate joint-forming region, yet a surprisingly minor role in ventralmost regions. Analysis of co-variance across multiple sequencing experiments further reveals clusters of co-regulated genes, with in situ hybridization confirming the domain-specific expression of novel genes. We then created loss-of-function alleles for 12 genes and uncovered antagonistic functions of two new Edn1 targets, follistatin a (fsta) and emx2, in regulating cartilaginous joints in the hyoid arch. Our unbiased discovery and functional analysis of genes with regional expression in zebrafish arch CNCCs reveals complex regulation by Edn1 and points to novel candidates for craniofacial disorders.
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Affiliation(s)
- Amjad Askary
- Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA 90033, USA
| | - Pengfei Xu
- Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA 90033, USA
| | - Lindsey Barske
- Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA 90033, USA
| | - Maxwell Bay
- Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA 90033, USA
| | - Paul Bump
- Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA 90033, USA
| | - Bartosz Balczerski
- Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA 90033, USA
| | - Michael A Bonaguidi
- Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA 90033, USA
| | - J Gage Crump
- Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA 90033, USA
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20
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Nichols JT, Blanco-Sánchez B, Brooks EP, Parthasarathy R, Dowd J, Subramanian A, Nachtrab G, Poss KD, Schilling TF, Kimmel CB. Ligament versus bone cell identity in the zebrafish hyoid skeleton is regulated by mef2ca. Development 2016; 143:4430-4440. [PMID: 27789622 PMCID: PMC5201047 DOI: 10.1242/dev.141036] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 10/18/2016] [Indexed: 12/11/2022]
Abstract
Heightened phenotypic variation among mutant animals is a well-known, but poorly understood phenomenon. One hypothetical mechanism accounting for mutant phenotypic variation is progenitor cells variably choosing between two alternative fates during development. Zebrafish mef2cab1086 mutants develop tremendously variable ectopic bone in their hyoid craniofacial skeleton. Here, we report evidence that a key component of this phenotype is variable fate switching from ligament to bone. We discover that a 'track' of tissue prone to become bone cells is a previously undescribed ligament. Fate-switch variability is heritable, and comparing mutant strains selectively bred to high and low penetrance revealed differential mef2ca mutant transcript expression between high and low penetrance strains. Consistent with this, experimental manipulation of mef2ca mutant transcripts modifies the penetrance of the fate switch. Furthermore, we discovered a transposable element that resides immediately upstream of the mef2ca locus and is differentially DNA methylated in the two strains, correlating with differential mef2ca expression. We propose that variable transposon epigenetic silencing underlies the variable mef2ca mutant bone phenotype, and could be a widespread mechanism of phenotypic variability in animals.
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Affiliation(s)
- James T Nichols
- Department of Biology, University of Oregon, Eugene, OR 97403, USA
| | | | - Elliott P Brooks
- Department of Biology, University of Oregon, Eugene, OR 97403, USA
| | | | - John Dowd
- Department of Biology, University of Oregon, Eugene, OR 97403, USA
| | - Arul Subramanian
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Gregory Nachtrab
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Kenneth D Poss
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Thomas F Schilling
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Charles B Kimmel
- Department of Biology, University of Oregon, Eugene, OR 97403, USA
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21
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Adrião A, Conceição N, Cancela ML. MEF2C orthologues from zebrafish: Evolution, expression and promoter regulation. Arch Biochem Biophys 2015; 591:43-56. [PMID: 26705761 DOI: 10.1016/j.abb.2015.12.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 11/24/2015] [Accepted: 12/13/2015] [Indexed: 12/26/2022]
Abstract
MEF2C is a crucial transcription factor for cranial neural crest cells development. An abnormal expression of this protein leads to severe abnormalities in craniofacial features. Recently, a human disease (MRD20) was described as a consequence of MEF2C haploinsufficiency. These patients show severe developmental delay, intellectual disability and dysmorphic features. Zebrafish presents two MEF2C orthologues, mef2ca and mef2cb. In this study we demonstrate a highly conserved pattern of chromosome localization for MEF2C between human and zebrafish, a similar protein sequence and tissue expression profile. We have focused our functional analysis on the zebrafish orthologue mef2cb. We identified three new exons through 5' RACE and described two new transcriptional start sites (TSS). These alternative TSS reflect the occurrence of two alternative promoters differentially regulated by nuclear factors related to craniofacial or neuronal development such as Sox9b, Sox10 and Runx2. We also predict that mef2cb gene may be post transcriptionally regulated by analysing the structure of its 5' UTR region, conserved throughout evolution. Our study provides new insights in MEF2C conservation and provides the first evidence of mef2cb regulation by both transcriptional and post transcriptional mechanisms, thus contributing to validate zebrafish as a good model for future studies concerning MEF2C dependent pathologies.
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Affiliation(s)
- Andreia Adrião
- Centre of Marine Sciences/CCMAR, University of Algarve, Portugal; PhD Program in Biomedical Sciences, University of Algarve, Portugal
| | - Natércia Conceição
- Centre of Marine Sciences/CCMAR, University of Algarve, Portugal; Dept of Biomedical Sciences and Medicine, University of Algarve, Portugal.
| | - M Leonor Cancela
- Centre of Marine Sciences/CCMAR, University of Algarve, Portugal; Dept of Biomedical Sciences and Medicine, University of Algarve, Portugal.
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22
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Analyzing Fluctuating Asymmetry with Geometric Morphometrics: Concepts, Methods, and Applications. Symmetry (Basel) 2015. [DOI: 10.3390/sym7020843] [Citation(s) in RCA: 208] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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