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Wen L, Man X, Luan J, Zhang S, Zhao C, Bao Y, Liu C, Feng X. Early-life exposure to five biodegradable plastics impairs eye development and visually-mediated behavior through disturbing hypothalamus-pituitary-thyroid (HPT) axis in zebrafish larvae. Comp Biochem Physiol C Toxicol Pharmacol 2024; 284:109981. [PMID: 39033795 DOI: 10.1016/j.cbpc.2024.109981] [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] [Received: 03/26/2024] [Revised: 07/09/2024] [Accepted: 07/18/2024] [Indexed: 07/23/2024]
Abstract
Biodegradable plastics have been commonly developed and applied as an alternative to traditional plastics, which cause environmental plastic pollution. However, biodegradable plastics still present limitations such as stringent degradation conditions and slow degradation rate, and may cause harm to the environment and organisms. Consequently, in this study, zebrafish was used to evaluate the effects of five biodegradable microplastics (MPs), polyglycolic acid (PGA), polylactic acid (PLA), polybutylene succinate (PBS), polyhydroxyalkanoate (PHA) and polybutylene adipate terephthalate (PBAT) exposure on the early development, retina morphology, visually-mediated behavior, and thyroid signaling at concentrations of 1 mg/L and 100 mg/L. The results indicated that all MPs induced decreased survival rate, reduced body length, smaller eyes, and smaller heads, affecting the early development of zebrafish larvae. Moreover, the thickness of retinal layers, including inner plexiform layer (IPL), outer nuclear layer (ONL), and retinal ganglion layer (RGL) was decreased, and the expression of key genes related to eye and retinal development was abnormally altered after all MPs exposure. Exposure to PBS and PBAT led to abnormal visually-mediated behavior, indicating likely affected the visual function. All MPs could also cause thyroid system disorders, among which alterations in the thyroid hormone receptors (TRs) genes could affect the retinal development of zebrafish larvae. In summary, biodegradable MPs exhibited eye developmental toxicity and likely impaired the visual function in zebrafish larvae. This provided new evidence for revealing the effects of biodegradable plastics on aquatic organism development and environmental risks to aquatic ecosystems.
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Affiliation(s)
- Liang Wen
- China Shenhua Coal to Liquid and Chemical CO., LTD. of China Energy, Beijing 100011, China
| | - Xiaoting Man
- College of Life Science, State Key Laboratory of Medicinal Chemical Biology, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin 300071, China
| | - Jialu Luan
- College of Life Science, State Key Laboratory of Medicinal Chemical Biology, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin 300071, China
| | - Shuhui Zhang
- College of Life Science, State Key Laboratory of Medicinal Chemical Biology, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin 300071, China
| | - Chengtian Zhao
- College of Life Science, State Key Laboratory of Medicinal Chemical Biology, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin 300071, China
| | - Yehua Bao
- College of Life Science, State Key Laboratory of Medicinal Chemical Biology, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin 300071, China
| | - Congzhi Liu
- China Shenhua Coal to Liquid and Chemical CO., LTD. of China Energy, Beijing 100011, China.
| | - Xizeng Feng
- College of Life Science, State Key Laboratory of Medicinal Chemical Biology, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin 300071, China.
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2
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Neil GJ, Kluttig KH, Allison WT. Determining Photoreceptor Cell Identity: Rod Versus Cone Fate Governed by tbx2b Opposing nrl. Invest Ophthalmol Vis Sci 2024; 65:39. [PMID: 38261312 PMCID: PMC10810017 DOI: 10.1167/iovs.65.1.39] [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: 09/22/2023] [Accepted: 12/28/2023] [Indexed: 01/24/2024] Open
Abstract
Purpose NRL is an influential transcription factor and central to animal modeling in ophthalmology. Disrupting NRL abrogates rod development and produces an excess of S-cones (also known as "UV cones" or "short-wavelength-sensitive1 [SWS1] cones"). Strikingly, mutations in zebrafish tbx2b produce the exact opposite phenotypes (excess rods and loss of SWS1 cones). We sought to define what genetic relationship exists, if any, between these transcription factors. We also infer whether these two phenotypes (altered rod abundance and altered SWS1 cone abundance) are independent versus inter-related. Methods Zebrafish mutants were bred to disrupt nrl and tbx2b in concert. Rods and SWS1 cones were quantified and characterized at ultrastructural and transcriptional levels. Results Considering single mutant zebrafish, we confirmed previously established phenotypes and noted that the number of rods lost in nrl-/- mutants is reflected by a concomitant increase in SWS1 cone abundance. The tbx2b-/- mutants present the opposite phenotype(s) but exhibit a similar trade-off in cell abundances, with lots of rods and a concomitant decrease in SWS1 cones. Double mutant nrl-/-;tbx2b-/- zebrafish recapitulate the nrl-/- mutant phenotype(s). Conclusions The tbx2b is thought to be required for producing SWS1 cones in zebrafish, but this can be over-ridden when nrl is absent. Regarding the altered cell abundances observed in either tbx2b-/- or nrl-/- mutants, the alterations in rod and SWS1 cones appear to not be two separate phenotypes but are instead a single intertwined outcome. The tbx2b and nrl are in an epistatic relationship, with nrl phenotypes dominating, implying that tbx2b is upstream of nrl in photoreceptor cell fate determination.
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Affiliation(s)
- Gavin J. Neil
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Kaitlyn H. Kluttig
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - W. Ted Allison
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
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3
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Shi Y, Qiu J, Li X, Lin Y, Li W, Hou J, Fu Y. Role of Thyroid Hormone in Dynamic Variation of gdf6a Gene during Metamorphosis of Paralichthys olivaceus. Int J Mol Sci 2023; 25:23. [PMID: 38203198 PMCID: PMC10779056 DOI: 10.3390/ijms25010023] [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: 11/12/2023] [Revised: 12/03/2023] [Accepted: 12/07/2023] [Indexed: 01/12/2024] Open
Abstract
The Japanese flounder (Paralichthys olivaceus) is a marine fish that undergoes a dramatic postembryonic metamorphosis, with the right eye shifting to the left and its lifestyle transitioning from planktonic to benthic. As the light environment of the habitat changes from bright to dim, its photoreceptor system also undergoes adaptive change. Growth differentiation factor 6a (Gdf6a) is a member of the BMP family, which plays a key role in regulating the dorsal-ventral pattern of the retina and photoreceptor fate, and the differentiation of different photoreceptors is also modulated by a thyroid hormone (TH) binding its receptor (TR). However, the relationship between gdf6a and TH and its role in the regulation of photoreceptors during flounder metamorphosis is still poorly understood. In this study, bioinformatics analysis showed that Gdf6a had a conserved TGFB structural domain and clusters with fishes. The expression analysis showed that the expression of gdf6a was highest in the eye tissue of adult flounder and tended to increase and then decrease during metamorphosis, reaching its highest levels at the peak of metamorphosis. Moreover, the expression of gdf6a increased in the early stages of metamorphosis after exogenous TH treatment, while it was inhibited after exogenous thiourea (a TH inhibitor, TU) treatment. To further investigate the targeting role of TH and gdf6a in the metamorphosis of flounder, the results of the Dual-Luciferase revealed that triiodothyronine (T3) may regulate the expression of gdf6a through TRβ. In conclusion, we speculate that TH influences the development of cone photoreceptors during the metamorphosis of the flounder by regulating the expression of gdf6a.
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Affiliation(s)
- Yaxin Shi
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China; (Y.S.); (J.Q.); (X.L.); (Y.L.); (W.L.)
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Junqiang Qiu
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China; (Y.S.); (J.Q.); (X.L.); (Y.L.); (W.L.)
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Xike Li
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China; (Y.S.); (J.Q.); (X.L.); (Y.L.); (W.L.)
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Yue Lin
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China; (Y.S.); (J.Q.); (X.L.); (Y.L.); (W.L.)
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Wenjuan Li
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China; (Y.S.); (J.Q.); (X.L.); (Y.L.); (W.L.)
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Jilun Hou
- Hebei Key Laboratory of the Bohai Sea Fish Germplasm Resources Conservation and Utilization, Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao 066100, China
| | - Yuanshuai Fu
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China; (Y.S.); (J.Q.); (X.L.); (Y.L.); (W.L.)
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
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4
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Chang J, Jiao M, Zhang Z, Liu W, Li W, Xu P, Wan B. Mechanistic insight into the adverse outcome of tire wear and road particle leachate exposure in zebrafish (Danio rerio) larvae. ENVIRONMENT INTERNATIONAL 2023; 178:108053. [PMID: 37356306 DOI: 10.1016/j.envint.2023.108053] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 05/15/2023] [Accepted: 06/17/2023] [Indexed: 06/27/2023]
Abstract
Tire wear particles (TWP) have become the major microplastic pollution in China. Road runoff containing TWP leachate can decrease the eye size and even induced mortality in the aquatic organisms. However, the toxic mechanism of TWP and road particles (RP) leachate on aquatic organisms is still unclear. In this study, the zebrafish embryos were exposed to TWP or RP leachate for 5 days at both environmental relevant and high concentrations. The adverse outcome pathways (AOPs) were screened from individual to molecular levels. The morphological and behavioral analysis demonstrated that the leachate exposure mainly impaired the eye development of zebrafish larvae and inhibited the larval swim behavior and phototactic response, which are the adverse outcomes. The phototransduction modulated by zebrafish retina was significantly down-regulated through transcriptomics and metabolomics analysis. The eye histopathological analysis showed that the decreased thickness of the retinal outer nuclear layer (ONL) and retinal pigmented epithelium (RPE) after leachate exposure were caused by the decreased photoreceptor cells. Moreover, the expression of NR2E3 and TPO genes showed concentration-dependent down-regulation after leachate exposure. The inhibition of photoreceptor cell proliferation was identified as the main reason for photoreceptor cell decrease in zebrafish larval eye. This study, for the first time, uncovered the underlying toxic mechanism of TWP and RP on zebrafish larval eyes.
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Affiliation(s)
- Jing Chang
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing RD 18, Beijing 100085, China
| | - Meng Jiao
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing RD 18, Beijing 100085, China; University of Chinese Academy of Sciences, Yuquan RD 19 a, Beijing 100049, China
| | - Zhaoguang Zhang
- Tongzhou Asphalt Factory, Beijing Municipal Road and Bridge Building Material Group Co. LTD, Beijing 101108, China
| | - Wentao Liu
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing RD 18, Beijing 100085, China; University of Chinese Academy of Sciences, Yuquan RD 19 a, Beijing 100049, China
| | - Wei Li
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing RD 18, Beijing 100085, China
| | - Peng Xu
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing RD 18, Beijing 100085, China
| | - Bin Wan
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing RD 18, Beijing 100085, China.
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5
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Kraft M, Gölz L, Rinderknecht M, Koegst J, Braunbeck T, Baumann L. Developmental exposure to triclosan and benzophenone-2 causes morphological alterations in zebrafish (Danio rerio) thyroid follicles and eyes. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:33711-33724. [PMID: 36495432 PMCID: PMC9736712 DOI: 10.1007/s11356-022-24531-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 11/28/2022] [Indexed: 05/31/2023]
Abstract
Thyroid hormones (THs) regulate a multitude of developmental and metabolic processes, which are responsible for vertebrate development, growth, and maintenance of homeostasis. THs also play a key role in neurogenesis of vertebrates and thus affect eye development, which is vital for foraging efficiency and for effective escape from predation. Currently, there are no validated test guidelines for the assessment of TH system-disrupting chemicals (THSDCs) in fish. Consequently, the present study was designed to demonstrate the suitability of novel thyroid-related endpoints in early life-stages of fish. Embryos of a transgenic zebrafish (Danio rerio) line expressing the reporter gene tg:mCherry in their thyrocytes were used to investigate the effects of the environmental THSDCs triclosan (TCS, antibacterial agent) and benzophenone-2 (BP-2, UV filter) on thyroid follicle and eye development. Both BP-2 and TCS caused thyroid follicle hyperplasia in transgenic zebrafish, thus confirming their role as THSDCs. The effect intensity on follicle size and fluorescence was comparable with a 1.7-fold increase for BP-2 and 1.6-fold for TCS. Alterations of the cellular structures of the retina indicate an impact of both substances on eye development, with a stronger impact of TCS. With respect to guideline development, results provide further evidence for the suitability of morphological changes in thyroid follicles and the eyes as novel endpoints for the sensitive assessment of THSD-related effects in fish.
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Affiliation(s)
- Maximilian Kraft
- Aquatic Toxicology and Ecology Section, Centre of Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 504, 69120, Heidelberg, Germany
| | - Lisa Gölz
- Aquatic Toxicology and Ecology Section, Centre of Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 504, 69120, Heidelberg, Germany
| | - Maximilian Rinderknecht
- Aquatic Toxicology and Ecology Section, Centre of Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 504, 69120, Heidelberg, Germany
| | - Johannes Koegst
- Aquatic Toxicology and Ecology Section, Centre of Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 504, 69120, Heidelberg, Germany
| | - Thomas Braunbeck
- Aquatic Toxicology and Ecology Section, Centre of Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 504, 69120, Heidelberg, Germany
| | - Lisa Baumann
- Aquatic Toxicology and Ecology Section, Centre of Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 504, 69120, Heidelberg, Germany.
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6
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Gölz L, Baumann L, Pannetier P, Braunbeck T, Knapen D, Vergauwen L. AOP Report: Thyroperoxidase Inhibition Leading to Altered Visual Function in Fish Via Altered Retinal Layer Structure. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2022; 41:2632-2648. [PMID: 35942927 DOI: 10.1002/etc.5452] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 07/29/2022] [Indexed: 06/15/2023]
Abstract
Thyroid hormones (THs) are involved in the regulation of many important physiological and developmental processes, including vertebrate eye development. Thyroid hormone system-disrupting chemicals (THSDCs) may have severe consequences, because proper functioning of the visual system is a key factor for survival in wildlife. However, the sequence of events leading from TH system disruption (THSD) to altered eye development in fish has not yet been fully described. The development of this adverse outcome pathway (AOP) was based on an intensive literature review of studies that focused on THSD and impacts on eye development, mainly in fish. In total, approximately 120 studies (up to the end of 2021) were used in the development of this AOP linking inhibition of the key enzyme for TH synthesis, thyroperoxidase (TPO), to effects on retinal layer structure and visual function in fish (AOP-Wiki, AOP 363). In a weight-of-evidence evaluation, the confidence levels were overall moderate, with ample studies showing the link between reduced TH levels and altered retinal layer structure. However, some uncertainties about the underlying mechanism(s) remain. Although the current weight-of-evidence evaluation is based on fish, the AOP is plausibly applicable to other vertebrate classes. Through the re-use of several building blocks, this AOP is connected to the AOPs leading from TPO and deiodinase inhibition to impaired swim bladder inflation in fish (AOPs 155-159), together forming an AOP network describing THSD in fish. This AOP network addresses the lack of thyroid-related endpoints in existing fish test guidelines for the evaluation of THSDCs. Environ Toxicol Chem 2022;41:2632-2648. © 2022 SETAC.
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Affiliation(s)
- Lisa Gölz
- Aquatic Ecology and Toxicology Research Group, Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
| | - Lisa Baumann
- Aquatic Ecology and Toxicology Research Group, Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
| | - Pauline Pannetier
- Aquatic Ecology and Toxicology Research Group, Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
| | - Thomas Braunbeck
- Aquatic Ecology and Toxicology Research Group, Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
| | - Dries Knapen
- Zebrafishlab, Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, Wilrijk, Belgium
| | - Lucia Vergauwen
- Zebrafishlab, Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, Wilrijk, Belgium
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7
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Folkerts EJ, Snihur KN, Zhang Y, Martin JW, Alessi DS, Goss GG. Embryonic cardio-respiratory impairments in rainbow trout (Oncorhynchus mykiss) following exposure to hydraulic fracturing flowback and produced water. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 310:119886. [PMID: 35934150 DOI: 10.1016/j.envpol.2022.119886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 07/29/2022] [Accepted: 07/31/2022] [Indexed: 06/15/2023]
Abstract
During hydraulic fracturing, wastewaters - termed flowback and produced water (FPW) - are created as a by-product during hydrocarbon extraction. Given the large volumes of FPW that a single well can produce, and the history of FPW release to surface water bodies, it is imperative to understand the hazards that hydraulic fracturing and FPW pose to aquatic biota. Using rainbow trout embryos as model organisms, we investigated impacts to cardio-respiratory system development and function following acute (48 h) and sub-chronic (28-day) FPW exposure by examining occurrences of developmental deformities, rates of embryonic respiration (MO2), and changes in expression of critical cardiac-specific genes. FPW-exposed embryos had significantly increased rates of pericardial edema, yolk-sac edema, and tail/trunk curvatures at hatch. Furthermore, when exposed at three days post-fertilization (dpf), acute 5% FPW exposures significantly increased embryonic MO2 through development until 15 dpf, where a switch to significantly reduced MO2 rates was subsequently recorded. A similar trend was observed during sub-chronic 1% FPW exposures. Interestingly, at certain specific developmental timepoints, previous salinity exposure seemed to affect embryonic MO2; a result not previously observed. Following acute FPW exposures, embryonic genes for cardiac development and function were significantly altered, although at termination of sub-chronic exposures, significant changes to these same genes were not found. Together, our evidence of induced developmental deformities, modified embryonic MO2, and altered cardiac transcript expression suggest that cardio-respiratory tissues are toxicologically targeted following FPW exposure in developing rainbow trout. These results may be helpful to regulatory bodies when developing hazard identification and risk management protocols concerning hydraulic fracturing activities.
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Affiliation(s)
- Erik J Folkerts
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada.
| | - Katherine N Snihur
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, T6G 2E3, Canada
| | - Yifeng Zhang
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, T6G 2G3, Alberta, Canada
| | - Jonathan W Martin
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, T6G 2G3, Alberta, Canada; Department of Environmental Science, Stockholm University, Stockholm, Sweden
| | - Daniel S Alessi
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, T6G 2E3, Canada
| | - Greg G Goss
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada; NRC- University of Alberta Nanotechnology Initiative, Edmonton, AB, T6G 2M9, Canada
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8
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Krueger LA, Morris AC. Eyes on CHARGE syndrome: Roles of CHD7 in ocular development. Front Cell Dev Biol 2022; 10:994412. [PMID: 36172288 PMCID: PMC9512043 DOI: 10.3389/fcell.2022.994412] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 08/19/2022] [Indexed: 11/13/2022] Open
Abstract
The development of the vertebrate visual system involves complex morphogenetic interactions of cells derived from multiple embryonic lineages. Disruptions in this process are associated with structural birth defects such as microphthalmia, anophthalmia, and coloboma (collectively referred to as MAC), and inherited retinal degenerative diseases such as retinitis pigmentosa and allied dystrophies. MAC and retinal degeneration are also observed in systemic congenital malformation syndromes. One important example is CHARGE syndrome, a genetic disorder characterized by coloboma, heart defects, choanal atresia, growth retardation, genital abnormalities, and ear abnormalities. Mutations in the gene encoding Chromodomain helicase DNA binding protein 7 (CHD7) cause the majority of CHARGE syndrome cases. However, the pathogenetic mechanisms that connect loss of CHD7 to the ocular complications observed in CHARGE syndrome have not been identified. In this review, we provide a general overview of ocular development and congenital disorders affecting the eye. This is followed by a comprehensive description of CHARGE syndrome, including discussion of the spectrum of ocular defects that have been described in this disorder. In addition, we discuss the current knowledge of CHD7 function and focus on its contributions to the development of ocular structures. Finally, we discuss outstanding gaps in our knowledge of the role of CHD7 in eye formation, and propose avenues of investigation to further our understanding of how CHD7 activity regulates ocular and retinal development.
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Affiliation(s)
| | - Ann C. Morris
- Department of Biology, University of Kentucky, Lexington, KY, United States
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9
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Carrington B, Bishop K, Sood R. A Comprehensive Review of Indel Detection Methods for Identification of Zebrafish Knockout Mutants Generated by Genome-Editing Nucleases. Genes (Basel) 2022; 13:857. [PMID: 35627242 PMCID: PMC9141975 DOI: 10.3390/genes13050857] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 05/06/2022] [Accepted: 05/10/2022] [Indexed: 11/16/2022] Open
Abstract
The use of zebrafish in functional genomics and disease modeling has become popular due to the ease of targeted mutagenesis with genome editing nucleases, i.e., zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats/Cas9 (CRISPR/Cas9). These nucleases, specifically CRISPR/Cas9, are routinely used to generate gene knockout mutants by causing a double stranded break at the desired site in the target gene and selecting for frameshift insertions or deletions (indels) caused by the errors during the repair process. Thus, a variety of methods have been developed to identify fish with indels during the process of mutant generation and phenotypic analysis. These methods range from PCR and gel-based low-throughput methods to high-throughput methods requiring specific reagents and/or equipment. Here, we provide a comprehensive review of currently used indel detection methods in zebrafish. By discussing the molecular basis for each method as well as their pros and cons, we hope that this review will serve as a comprehensive resource for zebrafish researchers, allowing them to choose the most appropriate method depending upon their budget, access to required equipment and the throughput needs of the projects.
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Affiliation(s)
| | | | - Raman Sood
- Zebrafish Core, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA; (B.C.); (K.B.)
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10
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Dhakal S, Rotem-Bamberger S, Sejd JR, Sebbagh M, Ronin N, Frey RA, Beitsch M, Batty M, Taler K, Blackerby JF, Inbal A, Stenkamp DL. Selective Requirements for Vascular Endothelial Cells and Circulating Factors in the Regulation of Retinal Neurogenesis. Front Cell Dev Biol 2021; 9:628737. [PMID: 33898420 PMCID: PMC8060465 DOI: 10.3389/fcell.2021.628737] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 03/17/2021] [Indexed: 01/01/2023] Open
Abstract
Development of the vertebrate eye requires signaling interactions between neural and non-neural tissues. Interactions between components of the vascular system and the developing neural retina have been difficult to decipher, however, due to the challenges of untangling these interactions from the roles of the vasculature in gas exchange. Here we use the embryonic zebrafish, which is not yet reliant upon hemoglobin-mediated oxygen transport, together with genetic strategies for (1) temporally-selective depletion of vascular endothelial cells, (2) elimination of blood flow through the circulation, and (3) elimination of cells of the erythroid lineage, including erythrocytes. The retinal phenotypes in these genetic systems were not identical, with endothelial cell-depleted retinas displaying laminar disorganization, cell death, reduced proliferation, and reduced cell differentiation. In contrast, the lack of blood flow resulted in a milder retinal phenotype showing reduced proliferation and reduced cell differentiation, indicating that an endothelial cell-derived factor(s) is/are required for laminar organization and cell survival. The lack of erythrocytes did not result in an obvious retinal phenotype, confirming that defects in retinal development that result from vascular manipulations are not due to poor gas exchange. These findings underscore the importance of the cardiovascular system supporting and controlling retinal development in ways other than supplying oxygen. In addition, these findings identify a key developmental window for these interactions and point to distinct functions for vascular endothelial cells vs. circulating factors.
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Affiliation(s)
- Susov Dhakal
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
| | - Shahar Rotem-Bamberger
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Josilyn R Sejd
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
| | - Meyrav Sebbagh
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Nathan Ronin
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Ruth A Frey
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
| | - Mya Beitsch
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Megan Batty
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States.,Department of Biology, Gonzaga University, Spokane, WA, United States
| | - Kineret Taler
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Jennifer F Blackerby
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States.,Department of Biology, Gonzaga University, Spokane, WA, United States
| | - Adi Inbal
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Deborah L Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
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Oel AP, Neil GJ, Dong EM, Balay SD, Collett K, Allison WT. Nrl Is Dispensable for Specification of Rod Photoreceptors in Adult Zebrafish Despite Its Deeply Conserved Requirement Earlier in Ontogeny. iScience 2020; 23:101805. [PMID: 33299975 PMCID: PMC7702016 DOI: 10.1016/j.isci.2020.101805] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 10/06/2020] [Accepted: 11/10/2020] [Indexed: 12/11/2022] Open
Abstract
The transcription factor NRL (neural retina leucine zipper) has been canonized as the master regulator of photoreceptor cell fate in the retina. NRL is necessary and sufficient to specify rod cell fate and to preclude cone cell fate in mice. By engineering zebrafish, we tested if NRL function has conserved roles beyond mammals or beyond nocturnal species, i.e., in a vertebrate possessing a greater and more typical diversity of cone sub-types. Transgenic expression of Nrl from zebrafish or mouse was sufficient to induce rod photoreceptor cells. Zebrafish nrl−/− mutants lacked rods (and had excess UV-sensitive cones) as young larvae; thus, the conservation of Nrl function between mice and zebrafish appears sound. Strikingly, however, rods were abundant in adult nrl−/− null mutant zebrafish. Rods developed in adults despite Nrl protein being undetectable. Therefore, a yet-to-be-revealed non-canonical pathway independent of Nrl is able to specify the fate of some rod photoreceptors. Nrl is conserved and sufficient to specify rod photoreceptors in the zebrafish retina Nrl is necessary for rod photoreceptors in early ontogeny of zebrafish larvae Zebrafish Nrl is functionally conserved with mouse and human NRL Remarkably, Nrl is dispensable for rod specification in adult zebrafish
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Affiliation(s)
- A Phillip Oel
- Department of Biological Sciences, University of Alberta, Edmonton AB, T7Y 1C4, Canada
| | - Gavin J Neil
- Department of Biological Sciences, University of Alberta, Edmonton AB, T7Y 1C4, Canada
| | - Emily M Dong
- Department of Biological Sciences, University of Alberta, Edmonton AB, T7Y 1C4, Canada
| | - Spencer D Balay
- Department of Biological Sciences, University of Alberta, Edmonton AB, T7Y 1C4, Canada
| | - Keon Collett
- Department of Biological Sciences, University of Alberta, Edmonton AB, T7Y 1C4, Canada
| | - W Ted Allison
- Department of Biological Sciences, University of Alberta, Edmonton AB, T7Y 1C4, Canada.,Department of Medical Genetics, University of Alberta, Edmonton AB, T6G 2R3, Canada
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Nadolski NJ, Balay SD, Wong CXL, Waskiewicz AJ, Hocking JC. Abnormal Cone and Rod Photoreceptor Morphogenesis in gdf6a Mutant Zebrafish. Invest Ophthalmol Vis Sci 2020; 61:9. [PMID: 32293666 PMCID: PMC7401959 DOI: 10.1167/iovs.61.4.9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Purpose Analysis of photoreceptor morphology and gene expression in mispatterned eyes of zebrafish growth differentiation factor 6a (gdf6a) mutants. Methods Rod and cone photoreceptors were compared between gdf6a mutant and control zebrafish from larval to late adult stages using transgenic labels, immunofluorescence, and confocal microscopy, as well as by transmission electron microscopy. To compare transcriptomes between larval gdf6a mutant and control zebrafish, RNA-Seq was performed on isolated eyes. Results Although rod and cone photoreceptors differentiate in gdf6a mutant zebrafish, the cells display aberrant growth and morphology. The cone outer segments, the light-detecting sensory endings, are reduced in size in the mutant larvae and fail to recover to control size at subsequent stages. In contrast, rods form temporarily expanded outer segments. The inner segments, which generate the required energy and proteins for the outer segments, are shortened in both rods and cones at all stages. RNA-Seq analysis provides a set of misregulated genes associated with the observed abnormal photoreceptor morphogenesis. Conclusions GDF6 mutations were previously identified in patients with Leber congenital amaurosis. Here, we reveal a unique photoreceptor phenotype in the gdf6a mutant zebrafish whereby rods and cones undergo abnormal maturation distinct for each cell type. Further, subsequent development shows partial recovery of cell morphology and maintenance of the photoreceptor layer. By conducting a transcriptomic analysis of the gdf6a larval eyes, we identified a collection of genes that are candidate regulators of photoreceptor size and morphology.
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Tsujimura T. Mechanistic insights into the evolution of the differential expression of tandemly arrayed cone opsin genes in zebrafish. Dev Growth Differ 2020; 62:465-475. [PMID: 32712957 DOI: 10.1111/dgd.12690] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/10/2020] [Accepted: 07/18/2020] [Indexed: 12/21/2022]
Abstract
The genome of many organisms contains several loci consisting of duplicated genes that are arrayed in tandem. The daughter genes produced by duplication typically exhibit differential expression patterns with each other or otherwise experience pseudogenization. Remarkably, opsin genes in fish are preserved after many duplications in different lineages. This fact indicates that fish opsin genes are characterized by a regulatory mechanism that could intrinsically facilitate the differentiation of the expression patterns. However, little is known about the mechanisms that underlie the differential expression patterns or how they were established during evolution. The loci of green (RH2)- and red (LWS)-sensitive cone opsin genes in zebrafish have been used as model systems to study the differential regulation of tandemly arrayed opsin genes. Over a decade of studies have uncovered several mechanistic features that might have assisted the differentiation and preservation of duplicated genes. Furthermore, recent progress in the understanding of the transcriptional process in general has added essential insights. In this article, the current understanding of the transcriptional regulation of differentially expressed tandemly arrayed cone opsin genes in zebrafish is summarized and a possible evolutionary scenario that could achieve this differentiation is discussed.
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Affiliation(s)
- Taro Tsujimura
- Institute for the Advanced Study of Human Biology (WPI-ASHBi), Kyoto University, Kyoto, Japan
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Deveau C, Jiao X, Suzuki SC, Krishnakumar A, Yoshimatsu T, Hejtmancik JF, Nelson RF. Thyroid hormone receptor beta mutations alter photoreceptor development and function in Danio rerio (zebrafish). PLoS Genet 2020; 16:e1008869. [PMID: 32569302 PMCID: PMC7332105 DOI: 10.1371/journal.pgen.1008869] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 07/02/2020] [Accepted: 05/18/2020] [Indexed: 01/16/2023] Open
Abstract
We investigate mutations in trβ2, a splice variant of thrb, identifying changes in function, structure, and behavior in larval and adult zebrafish retinas. Two N-terminus CRISPR mutants were identified. The first is a 6BP+1 insertion deletion frameshift resulting in a truncated protein. The second is a 3BP in frame deletion with intact binding domains. ERG recordings of isolated cone signals showed that the 6BP+1 mutants did not respond to red wavelengths of light while the 3BP mutants did respond. 6BP+1 mutants lacked optomotor and optokinetic responses to red/black and green/black contrasts. Both larval and adult 6BP+1 mutants exhibit a loss of red-cone contribution to the ERG and an increase in UV-cone contribution. Transgenic reporters show loss of cone trβ2 activation in the 6BP+1 mutant but increase in the density of cones with active blue, green, and UV opsin genes. Antibody reactivity for red-cone LWS1 and LWS2 opsin was absent in the 6BP+1 mutant, as was reactivity for arrestin3a. Our results confirm a critical role for trβ2 in long-wavelength cone development. There are four cone photoreceptors responsible for color vision in zebrafish: red, green, blue, and UV. The thyroid hormone receptor trβ2 is localized in the vertebrate retina. We know that it is necessary for the development of cones expressing long-wavelength-sensitive opsins (red cones), but here we investigate the functional alterations that accompany a loss of trβ2. Our work contributes to the ongoing investigations of retinal development and the involvement of thyroid hormone receptors. As suggested by previous morphological findings, fish became red colorblind when trβ2 was knocked out, and the contributions of the other three cone types shifted. Our work highlights the plasticity of photoreceptor patterning as we see changes in opsin peaks and cone sensitivity, increases in contributions of UV cones, and an attempt at a mosaic pattern in the adult retina, all in the absence of trβ2 and red cones. We now have an increased understanding of mechanisms underlying retinal development.
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Affiliation(s)
- Ciana Deveau
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Rockville, Maryland, United States of America
- * E-mail:
| | - Xiaodong Jiao
- National Eye Institute, National Institutes of Health, Rockville, Maryland, United States of America
| | - Sachihiro C. Suzuki
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Asha Krishnakumar
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Rockville, Maryland, United States of America
| | | | - J Fielding Hejtmancik
- National Eye Institute, National Institutes of Health, Rockville, Maryland, United States of America
| | - Ralph F. Nelson
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Rockville, Maryland, United States of America
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