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Ran R, Li L, Xu T, Huang J, He H, Chen Y. Revealing mitf functions and visualizing allografted tumor metastasis in colorless and immunodeficient Xenopus tropicalis. Commun Biol 2024; 7:275. [PMID: 38443437 PMCID: PMC10915148 DOI: 10.1038/s42003-024-05967-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 02/23/2024] [Indexed: 03/07/2024] Open
Abstract
Transparent immunodeficient animal models not only enhance in vivo imaging investigations of visceral organ development but also facilitate in vivo tracking of transplanted tumor cells. However, at present, transparent and immunodeficient animal models are confined to zebrafish, presenting substantial challenges for real-time, in vivo imaging studies addressing specific biological inquiries. Here, we employed a mitf-/-/prkdc-/-/il2rg-/- triple-knockout strategy to establish a colorless and immunodeficient amphibian model of Xenopus tropicalis. By disrupting the mitf gene, we observed the loss of melanophores, xanthophores, and granular glands in Xenopus tropicalis. Through the endogenous mitf promoter to drive BRAFV600E expression, we confirmed mitf expression in melanophores, xanthophores and granular glands. Moreover, the reconstruction of the disrupted site effectively reinstated melanophores, xanthophores, and granular glands, further highlighting the crucial role of mitf as a regulator in their development. By crossing mitf-/- frogs with prkdc-/-/il2rg-/- frogs, we generated a mitf-/-/prkdc-/-/il2rg-/- Xenopus tropicalis line, providing a colorless and immunodeficient amphibian model. Utilizing this model, we successfully observed intravital metastases of allotransplanted xanthophoromas and migrations of allotransplanted melanomas. Overall, colorless and immunodeficient Xenopus tropicalis holds great promise as a valuable platform for tumorous and developmental biology research.
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Affiliation(s)
- Rensen Ran
- Department of Chemical Biology, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, China.
- Guangdong Provincial Engineering Research Center of Molecular Imaging, The Fifth Affiliated Hospital of Sun Yat-sen University, 519000, Zhuhai, China.
| | - Lanxin Li
- Department of Chemical Biology, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, China
| | - Tingting Xu
- Fujian Medical University Union Hospital, 350001, Fuzhou, China
| | - Jixuan Huang
- Department of Chemical Biology, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, China
| | - Huanhuan He
- Guangdong Provincial Engineering Research Center of Molecular Imaging, The Fifth Affiliated Hospital of Sun Yat-sen University, 519000, Zhuhai, China
| | - Yonglong Chen
- Department of Chemical Biology, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, China.
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Nakajima K, Tazawa I, Furuno N. Generation of translucent Xenopus tropicalis through triple knockout of pigmentation genes. Dev Growth Differ 2023; 65:591-598. [PMID: 37750430 DOI: 10.1111/dgd.12891] [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: 08/27/2023] [Revised: 09/13/2023] [Accepted: 09/19/2023] [Indexed: 09/27/2023]
Abstract
Amphibians generally have three types of pigment cells, namely, melanophores (black and brown), xanthophores (yellow and red), and iridophores (iridescent). Single knockout of the tyr, slc2a7, and hps6 genes in Xenopus tropicalis results in the absence of melanophores, xanthophores, and iridophores, respectively. The generation of triple- knockout (3KO) X. tropicalis for these three genes could allow for observation of internal organs without sacrificing the animals, which would be transparent due to the absence of pigments. In this study, we generated 3KO X. tropicalis, which is one of the most widely used model amphibians, through crossing of a slc2a7 single-knockout frog with a tyr and hps6 double-knockout frog, followed by intercrossing of their offspring. The 3KO tadpoles had transparent bodies like the nop mutant and the frogs had translucent bodies. This translucency allowed us to observe the heart, lungs, stomach, liver, and digestive tract through the ventral body skin without surgery. After intravital staining, 3KO X. tropicalis showed much clearer fluorescent signals of mineralized tissues compared with the wild type. These 3KO X. tropicalis provide a useful mutant line for continuous observation of internal organs and fluorescent signals in the body. In particular, such 3KO frogs would revolutionize fluorescence monitoring in transgenic tadpoles and frogs expressing fluorescent proteins.
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Affiliation(s)
- Keisuke Nakajima
- Division of Embryology, Amphibian Research Center, Hiroshima University, Higashihiroshima, Japan
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Japan
| | - Ichiro Tazawa
- Division of Embryology, Amphibian Research Center, Hiroshima University, Higashihiroshima, Japan
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Japan
| | - Nobuaki Furuno
- Division of Embryology, Amphibian Research Center, Hiroshima University, Higashihiroshima, Japan
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Japan
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Taboada C, Delia J, Chen M, Ma C, Peng X, Zhu X, Jiang L, Vu T, Zhou Q, Yao J, O’Connell L, Johnsen S. Glassfrogs conceal blood in their liver to maintain transparency. Science 2022; 378:1315-1320. [PMID: 36548427 PMCID: PMC9984244 DOI: 10.1126/science.abl6620] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Transparency in animals is a complex form of camouflage involving mechanisms that reduce light scattering and absorption throughout the organism. In vertebrates, attaining transparency is difficult because their circulatory system is full of red blood cells (RBCs) that strongly attenuate light. Here, we document how glassfrogs overcome this challenge by concealing these cells from view. Using photoacoustic imaging to track RBCs in vivo, we show that resting glassfrogs increase transparency two- to threefold by removing ~89% of their RBCs from circulation and packing them within their liver. Vertebrate transparency thus requires both see-through tissues and active mechanisms that "clear" respiratory pigments from these tissues. Furthermore, glassfrogs' ability to regulate the location, density, and packing of RBCs without clotting offers insight in metabolic, hemodynamic, and blood-clot research.
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Affiliation(s)
- Carlos Taboada
- Biology Department, Duke University, Durham, NC, USA,Department of Biomedical Engineering, Duke University, Durham, NC, USA,Corresponding author.(C.T.);(J.D.);(J.Y.)
| | - Jesse Delia
- Department of Biomedical Engineering, Duke University, Durham, NC, USA,Department of Biology, Stanford University, Stanford, CA, USA,Division of Vertebrate Zoology and Richard Gilder Graduate School, American Museum of Natural History, New York, NY, USA,Corresponding author.(C.T.);(J.D.);(J.Y.)
| | - Maomao Chen
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Chenshuo Ma
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Xiaorui Peng
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Xiaoyi Zhu
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Laiming Jiang
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Tri Vu
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Qifa Zhou
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA,Department of Ophthalmology, University of Southern California, Los Angeles, CA 90033, USA,USC Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA
| | - Junjie Yao
- Department of Biomedical Engineering, Duke University, Durham, NC, USA,Corresponding author.(C.T.);(J.D.);(J.Y.)
| | | | - Sönke Johnsen
- Biology Department, Duke University, Durham, NC, USA
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Intravital staining to detect mineralization in
Xenopus tropicalis
during and after metamorphosis. Dev Growth Differ 2022; 64:368-378. [DOI: 10.1111/dgd.12804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 05/15/2022] [Accepted: 06/05/2022] [Indexed: 11/26/2022]
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Haynes EM, Ulland TK, Eliceiri KW. A Model of Discovery: The Role of Imaging Established and Emerging Non-mammalian Models in Neuroscience. Front Mol Neurosci 2022; 15:867010. [PMID: 35493325 PMCID: PMC9046975 DOI: 10.3389/fnmol.2022.867010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/18/2022] [Indexed: 11/24/2022] Open
Abstract
Rodents have been the dominant animal models in neurobiology and neurological disease research over the past 60 years. The prevalent use of rats and mice in neuroscience research has been driven by several key attributes including their organ physiology being more similar to humans, the availability of a broad variety of behavioral tests and genetic tools, and widely accessible reagents. However, despite the many advances in understanding neurobiology that have been achieved using rodent models, there remain key limitations in the questions that can be addressed in these and other mammalian models. In particular, in vivo imaging in mammals at the cell-resolution level remains technically difficult and demands large investments in time and cost. The simpler nervous systems of many non-mammalian models allow for precise mapping of circuits and even the whole brain with impressive subcellular resolution. The types of non-mammalian neuroscience models available spans vertebrates and non-vertebrates, so that an appropriate model for most cell biological questions in neurodegenerative disease likely exists. A push to diversify the models used in neuroscience research could help address current gaps in knowledge, complement existing rodent-based bodies of work, and bring new insight into our understanding of human disease. Moreover, there are inherent aspects of many non-mammalian models such as lifespan and tissue transparency that can make them specifically advantageous for neuroscience studies. Crispr/Cas9 gene editing and decreased cost of genome sequencing combined with advances in optical microscopy enhances the utility of new animal models to address specific questions. This review seeks to synthesize current knowledge of established and emerging non-mammalian model organisms with advances in cellular-resolution in vivo imaging techniques to suggest new approaches to understand neurodegeneration and neurobiological processes. We will summarize current tools and in vivo imaging approaches at the single cell scale that could help lead to increased consideration of non-mammalian models in neuroscience research.
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Affiliation(s)
- Elizabeth M. Haynes
- Morgridge Institute for Research, Madison, WI, United States
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI, United States
| | - Tyler K. Ulland
- Department of Pathology, University of Wisconsin-Madison, Madison, WI, United States
| | - Kevin W. Eliceiri
- Morgridge Institute for Research, Madison, WI, United States
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI, United States
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States
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Bertolesi GE, Debnath N, Malik HR, Man LLH, McFarlane S. Type II Opsins in the Eye, the Pineal Complex and the Skin of Xenopus laevis: Using Changes in Skin Pigmentation as a Readout of Visual and Circadian Activity. Front Neuroanat 2022; 15:784478. [PMID: 35126061 PMCID: PMC8814574 DOI: 10.3389/fnana.2021.784478] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 12/13/2021] [Indexed: 01/17/2023] Open
Abstract
The eye, the pineal complex and the skin are important photosensitive organs. The African clawed frog, Xenopus laevis, senses light from the environment and adjusts skin color accordingly. For example, light reflected from the surface induces camouflage through background adaptation while light from above produces circadian variation in skin pigmentation. During embryogenesis, background adaptation, and circadian skin variation are segregated responses regulated by the secretion of α-melanocyte-stimulating hormone (α-MSH) and melatonin through the photosensitivity of the eye and pineal complex, respectively. Changes in the color of skin pigmentation have been used as a readout of biochemical and physiological processes since the initial purification of pineal melatonin from pigs, and more recently have been employed to better understand the neuroendocrine circuit that regulates background adaptation. The identification of 37 type II opsin genes in the genome of the allotetraploid X. laevis, combined with analysis of their expression in the eye, pineal complex and skin, is contributing to the elucidation of the role of opsins in the different photosensitive organs, but also brings new questions and challenges. In this review, we analyze new findings regarding the anatomical localization and functions of type II opsins in sensing light. The contribution of X. laevis in revealing the neuroendocrine circuits that regulate background adaptation and circadian light variation through changes in skin pigmentation is discussed. Finally, the presence of opsins in X. laevis skin melanophores is presented and compared with the secretory melanocytes of birds and mammals.
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Affiliation(s)
- Gabriel E. Bertolesi
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada
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