| 1. |
- Leyhr, Jake, et al.
(author)
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A novel cis-regulatory element drives early expression of Nkx3.2 in the gnathostome primary jaw joint
- 2022
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In: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 11
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Journal article (peer-reviewed)abstract
- The acquisition of movable jaws was a major event during vertebrate evolution. The role of NK3 homeobox 2 (Nkx3.2) transcription factor in patterning the primary jaw joint of gnathostomes (jawed vertebrates) is well known, however knowledge about its regulatory mechanism is lacking. In this study, we report a proximal enhancer element of Nkx3.2 that is deeply conserved in most gnathostomes but undetectable in the jawless hagfish and lamprey. This enhancer is active in the developing jaw joint region of the zebrafish Danio rerio, and was thus designated as jaw joint regulatory sequence 1 (JRS1). We further show that JRS1 enhancer sequences from a range of gnathostome species, including a chondrichthyan and mammals, have the same activity in the jaw joint as the native zebrafish enhancer, indicating a high degree of functional conservation despite the divergence of cartilaginous and bony fish lineages or the transition of the primary jaw joint into the middle ear of mammals. Finally, we show that deletion of JRS1 from the zebrafish genome using CRISPR/Cas9 results in a significant reduction of early gene expression of nkx3.2 and leads to a transient jaw joint deformation and partial fusion. Emergence of this Nkx3.2 enhancer in early gnathostomes may have contributed to the origin and shaping of the articulating surfaces of vertebrate jaws.
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| 2. |
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| 3. |
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| 4. |
- Waldmann, Laura, et al.
(author)
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The Broad Role of Nkx3.2 in the Development of the Zebrafish Axial Skeleton
- 2024
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Other publication (other academic/artistic)abstract
- The transcription factor Nkx3.2 (Bapx1) is an important chondrocyte maturation inhibitor. Previous Nkx3.2 knock-down and overexpression studies in non-mammalian gnathostomes have focused on its role in primary jaw joint development, while little is known about the function of this gene in broader skeletal development. We generated CRISPR/Cas9 knockout of nkx3.2 in zebrafish and applied a range of techniques to characterize skeletal phenotypes at developmental stages from larva to adult, revealing fusions in bones of the occiput, the loss or deformation of bony elements derived from basiventral cartilages of the vertebrae, and an increased length of the proximal radials of the dorsal and anal fins. These phenotypes are reminiscent of Nkx3.2 knockout phenotypes in mammals, suggesting that the function of this gene in axial skeletal development is ancestral to osteichthyans. Our results highlight the broad role of nkx3.2 in zebrafish skeletal development and its context-specific functions in different skeletal elements.
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| 5. |
- Waldmann, Laura, et al.
(author)
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The broad role of Nkx3.2 in the development of the zebrafish axial skeleton
- 2021
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 16:8
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Journal article (peer-reviewed)abstract
- The transcription factor Nkx3.2 (Bapx1) is an important chondrocyte maturation inhibitor. Previous Nkx3.2 knockdown and overexpression studies in non-mammalian gnathostomes have focused on its role in primary jaw joint development, while the function of this gene in broader skeletal development is not fully described. We generated a mutant allele of nkx3.2 in zebrafish with CRISPR/Cas9 and applied a range of techniques to characterize skeletal phenotypes at developmental stages from larva to adult, revealing loss of the jaw joint, fusions in bones of the occiput, morphological changes in the Weberian apparatus, and the loss or deformation of bony elements derived from basiventral cartilages of the vertebrae. Axial phenotypes are reminiscent of Nkx3.2 knockout in mammals, suggesting that the function of this gene in axial skeletal development is ancestral to osteichthyans. Our results highlight the broad role of nkx3.2 in zebrafish skeletal development and its context-specific functions in different skeletal elements.
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| 6. |
- Waldmann, Laura, et al.
(author)
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The Role of Gdf5 in the Development of the Zebrafish Fin Endoskeleton
- 2022
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In: Developmental Dynamics. - : John Wiley & Sons. - 1058-8388 .- 1097-0177. ; 251:9, s. 1535-1549
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Journal article (peer-reviewed)abstract
- The development of the vertebrate skeleton requires a complex interaction of multiple factors to facilitate correct shaping and positioning of bones and joints. Growth and differentiation factor 5 (Gdf5), a member of the transforming growth factor-beta family (TGF-beta) is involved in patterning appendicular skeletal elements including joints. Expression of gdf5 in zebrafish has been detected within the first pharyngeal arch jaw joint, fin mesenchyme condensations and segmentation zones in median fins, however little is known about the functional role of Gdf5 outside of Amniota. We generated CRISPR/Cas9 knockout of gdf5 in zebrafish and analysed the resulting phenotype at different developmental stages. Homozygous gdf5 mutant zebrafish display truncated median fin endoskeletal elements and loss of posterior radials in the pectoral fins. These findings are consistent with phenotypes observed in human and mouse appendicular skeleton in response to Gdf5 knockout, suggesting a broadly conserved role for Gdf5 in Osteichthyes.
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| 7. |
- Zhang, Hanqing, et al.
(author)
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zOPT: an open source optical projection tomography system and methods for rapid 3D zebrafish imaging
- 2020
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In: Biomedical Optics Express. - : The Optical Society. - 2156-7085. ; 11:8, s. 4290-4305
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Journal article (peer-reviewed)abstract
- Optical projection tomography (OPT) is a 3D imaging alternative to conventional microscopy which allows imaging of millimeter-sized object with isotropic micrometer resolution. The zebrafish is an established model organism and an important tool used in genetic and chemical screening. The size and optical transparency of the embryo and larva makes them well suited for imaging using OPT. Here, we present an open-source implementation of an OPT platform, built around a customized sample stage, 3D-printed parts and open source algorithms optimized for the system. We developed a versatile automated workflow including a two-step image processing approach for correcting the center of rotation and generating accurate 3D reconstructions. Our results demonstrate high-quality 3D reconstruction using synthetic data as well as real data of live and fixed zebrafish. The presented 3D-printable OPT platform represents a fully open design, low-cost and rapid loading and unloading of samples. Our system offers the opportunity for researchers with different backgrounds to setup and run OPT for large scale experiments, particularly in studies using zebrafish larvae as their key model organism.
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| 9. |
- Debiais-Thibaud, Melanie, et al.
(author)
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Skeletal Mineralization in Association with Type X Collagen Expression Is an Ancestral Feature for Jawed Vertebrates
- 2019
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In: Molecular biology and evolution. - : Oxford University Press (OUP). - 0737-4038 .- 1537-1719. ; 36:10, s. 2265-2276
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Journal article (peer-reviewed)abstract
- In order to characterize the molecular bases of mineralizing cell evolution, we targeted type X collagen, a nonfibrillar network forming collagen encoded by the Col10a1 gene. It is involved in the process of endochondral ossification in ray-finned fishes and tetrapods (Osteichthyes), but until now unknown in cartilaginous fishes (Chondrichthyes). We show that holocephalans and elasmobranchs have respectively five and six tandemly duplicated Col10a1 gene copies that display conserved genomic synteny with osteichthyan Col10a1 genes. All Col10a1 genes in the catshark Scyliorhinus canicula are expressed in ameloblasts and/or odontoblasts of teeth and scales, during the stages of extracellular matrix protein secretion and mineralization. Only one duplicate is expressed in the endoskeletal (vertebral) mineralizing tissues. We also show that the expression of type X collagen is present in teeth of two osteichthyans, the zebrafish Danio rerio and the western clawed frog Xenopus tropicalis, indicating an ancestral jawed vertebrate involvement of type X collagen in odontode formation. Our findings push the origin of Col10a1 gene prior to the divergence of osteichthyans and chondrichthyans, and demonstrate its ancestral association with mineralization of both the odontode skeleton and the endoskeleton.
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| 10. |
- Haitina, Tatjana, Docent, 1981-, et al.
(author)
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Evolutionary Genomics of Odontode Tissues
- 2023. - 1
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In: Odontodes. - Boca Raton : CRC Press. - 9781003439653 ; , s. 41-
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Book chapter (peer-reviewed)abstract
- Teeth, scales, fin spines, and other odontodes are hot topics in evolutionary biology due to their great variation in number, shape, and anatomical localization in vertebrates as a result of different types of adaptations. Structural adaptation arose through variations in the composition of the enamel/enameloid and dentin layers that build up the mineralized components of teeth and other odontodes. These variations are known from both fossil and extant groups of vertebrates and rely on differences in the proteins secreted by the specialized odontode cells, ameloblasts, and odontoblasts.In this chapter, we focus on recent genomic and gene expression data to better understand the evolution of gene families engaged in the processes of secretion, mineralization, and maturation of odontode matrices. Our focus will be structural matrix proteins (collagenous and non-collagenous), calcium-interacting proteins necessary for mineralization, and proteins regulating matrix degradation over the course of tissue maturation.
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