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Liu H, Xie L, Xiao Y, Ran R, Fang Y, Yang B, Tan L, Xu J, Lu S, Dong Y, Cui L. Conversion of Retinoids along the Marine Food Chain Contributes to Adverse Impacts on the Spine, Liver, and Intestinal Health of the Marine Medaka ( Oryzias melastigma). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:12921-12932. [PMID: 38965053 PMCID: PMC11271003 DOI: 10.1021/acs.est.4c02634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 06/21/2024] [Accepted: 06/21/2024] [Indexed: 07/06/2024]
Abstract
Marine microalgae serve as an aquaculture bait. To enhance algal cell growth and breeding profits, high-intensity light conditions are standard for cultivating bait microalgae, potentially altering microalgal metabolite production. This research revealed that Thalassiosira pseudonana, when subjected to high-intensity light conditions, accumulated significant quantities of retinal (RAL) that transferred through the food chain and transformed into all-trans retinoic acid (atRA) in marine medaka. The study further explored the toxic effects on individual fish and specific tissues, as well as the mechanisms behind this toxicity. The accumulation of atRA in the liver, intestine, and spinal column resulted in structural damage and tissue inflammation, as well as oxidative stress. It also down-regulated the gene transcription levels of key pathways involved in immune function and growth. Furthermore, it disrupted the homeostasis of the intestinal microbial communities. The implications for wildlife and human health, which are influenced by the regulation of microalgal metabolite accumulation and their transfer via the food chain, require further investigation and could hold broader significance.
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Affiliation(s)
- Haisu Liu
- Research
Center of Harmful Algae and Marine Biology, Key Laboratory of Eutrophication
and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, PR China
| | - Lei Xie
- Research
Center of Harmful Algae and Marine Biology, Key Laboratory of Eutrophication
and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, PR China
| | - Yang Xiao
- Research
Center of Harmful Algae and Marine Biology, Key Laboratory of Eutrophication
and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, PR China
| | - Ruiwei Ran
- Guangzhou
Key Laboratory of Subtropical Biodiversity and Biomonitoring, College
of Life Science, South China Normal University, Guangzhou 510631, PR China
| | - Yuhang Fang
- Research
Center of Harmful Algae and Marine Biology, Key Laboratory of Eutrophication
and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, PR China
| | - Baoling Yang
- Research
Center of Harmful Algae and Marine Biology, Key Laboratory of Eutrophication
and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, PR China
| | - Liying Tan
- Research
Center of Harmful Algae and Marine Biology, Key Laboratory of Eutrophication
and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, PR China
| | - Juanchan Xu
- Research
Center of Harmful Algae and Marine Biology, Key Laboratory of Eutrophication
and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, PR China
| | - Songhui Lu
- Research
Center of Harmful Algae and Marine Biology, Key Laboratory of Eutrophication
and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, PR China
- Southern
Marine Science and Engineering Guangdong Laboratory, Zhuhai 519080, PR China
| | - Yuelei Dong
- Guangzhou
Key Laboratory of Subtropical Biodiversity and Biomonitoring, College
of Life Science, South China Normal University, Guangzhou 510631, PR China
| | - Lei Cui
- Research
Center of Harmful Algae and Marine Biology, Key Laboratory of Eutrophication
and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, PR China
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Wang X, Ma T, Wei C, Liu J, Yu T, Zou Y, Liu S, Yang Z, Xi J. Toxic effects of exogenous retinoic acid on the neurodevelopment of zebrafish (Danio rerio) embryos. Neurotoxicol Teratol 2023; 100:107291. [PMID: 37689270 DOI: 10.1016/j.ntt.2023.107291] [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: 05/07/2023] [Revised: 08/30/2023] [Accepted: 08/30/2023] [Indexed: 09/11/2023]
Abstract
Endogenous retinoic acid (RA) is essential for embryonic development and maintaining adult physiological processes. Human-caused RA residues in the environment threaten the survival of organisms in the environment. We employed zebrafish as a model to explore the developmental impacts of excess RA. We used exogenous RA to raise the amount of RA signal in the embryos and looked at the effects of excess RA on embryonic morphological development. Upregulation of the RA signal significantly reduced embryo hatching and increased embryo malformation. To further understand the neurotoxic impact of RA signaling on early neurodevelopment, we measured the expression of neurodevelopmental marker genes and cell death and proliferation markers in zebrafish embryos. Exogenous RA disrupted stem cell (SC) and neuron marker gene expression and exacerbated apoptosis in the embryos. Furthermore, we looked into the links between the transcriptional coactivator RBM14 and RA signaling to better understand the mechanism of RA neurotoxicity. There was a negative interaction between RA signaling and the transcription coactivator RBM14, and the morpholino-induced RBM14 down-regulation can partially block the effects of RAR antagonist BMS493-induced RA signaling inhibition on embryonic malformation and cell apoptosis. In conclusion, exogenous RA causes neurodevelopmental toxicity, and RBM14 may be involved in this neurotoxic process.
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Affiliation(s)
- Xiaoxuan Wang
- Institute of Pharmaceutical Innovation, Hubei Province Key Laboratory of Occupational Hazard Identification and Control, School of Medicine, Wuhan University of Science and Technology, Wuhan, China
| | - Ting Ma
- Institute of Pharmaceutical Innovation, Hubei Province Key Laboratory of Occupational Hazard Identification and Control, School of Medicine, Wuhan University of Science and Technology, Wuhan, China
| | - Cizhao Wei
- Demonstration Center for Experimental Basic Medicine Education, Wuhan University Taikang Medical School (School of Basic Medical Sciences), Wuhan, Hubei, China
| | - Juan Liu
- Institute of Pharmaceutical Innovation, Hubei Province Key Laboratory of Occupational Hazard Identification and Control, School of Medicine, Wuhan University of Science and Technology, Wuhan, China
| | - Ting Yu
- Institute of Pharmaceutical Innovation, Hubei Province Key Laboratory of Occupational Hazard Identification and Control, School of Medicine, Wuhan University of Science and Technology, Wuhan, China
| | - Yu Zou
- Institute of Pharmaceutical Innovation, Hubei Province Key Laboratory of Occupational Hazard Identification and Control, School of Medicine, Wuhan University of Science and Technology, Wuhan, China
| | - Song Liu
- Institute of Pharmaceutical Innovation, Hubei Province Key Laboratory of Occupational Hazard Identification and Control, School of Medicine, Wuhan University of Science and Technology, Wuhan, China
| | - Zheqiong Yang
- Demonstration Center for Experimental Basic Medicine Education, Wuhan University Taikang Medical School (School of Basic Medical Sciences), Wuhan, Hubei, China.
| | - Jinlei Xi
- Institute of Pharmaceutical Innovation, Hubei Province Key Laboratory of Occupational Hazard Identification and Control, School of Medicine, Wuhan University of Science and Technology, Wuhan, China.
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Sehnal L, Smutná M, Bláhová L, Babica P, Šplíchalová P, Hilscherová K. The Origin of Teratogenic Retinoids in Cyanobacteria. Toxins (Basel) 2022; 14:toxins14090636. [PMID: 36136574 PMCID: PMC9501733 DOI: 10.3390/toxins14090636] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/01/2022] [Accepted: 09/13/2022] [Indexed: 11/16/2022] Open
Abstract
Although information about the occurrence and distribution of retinoids in the environment is scarce, cyanobacterial water blooms have been identified as a significant source of these small molecules. Despite the confirmed presence of retinoids in the freshwater blooms dominated by cyanobacteria and their described teratogenic effects, reliable identification of retinoid producers and the mechanism of their biosynthesis is missing. In this study, the cultures of several taxonomically diverse species of axenic cyanobacteria were confirmed as significant producers of retinoid-like compounds. The consequent bioinformatic analysis suggested that the enzymatic background required for the biosynthesis of all-trans retinoic acid from retinal is not present across phylum Cyanobacteria. However, we demonstrated that retinal conversion into other retinoids can be mediated non-enzymatically by free radical oxidation, which leads to the production of retinoids widely detected in cyanobacteria and environmental water blooms, such as all-trans retinoic acid or all-trans 5,6epoxy retinoic acid. Importantly, the production of these metabolites by cyanobacteria in association with the mass development of water blooms can lead to adverse impacts in aquatic ecosystems regarding the described teratogenicity of retinoids. Moreover, our finding that retinal can be non-enzymatically converted into more bioactive retinoids, also in water, and out of the cells, increases the environmental significance of this process.
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Yeung KWY, Ho KKY, Zhou GJ, Ruan Y, Lam PKS, Leung KMY. Spatiotemporal variations of retinoic acids and their metabolites in the marine environment of Hong Kong. MARINE POLLUTION BULLETIN 2022; 181:113878. [PMID: 35779385 DOI: 10.1016/j.marpolbul.2022.113878] [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: 03/23/2022] [Revised: 06/20/2022] [Accepted: 06/21/2022] [Indexed: 06/15/2023]
Abstract
Excessive intake of retinoic acids (RAs) and the oxidative metabolites, 4-oxo-RAs, can lead to abnormal morphological development in animals. This study investigated spatiotemporal variations of concentrations and compositions of these compounds in Hong Kong's seawater and during algal blooms. Total concentrations of the studied compounds in seawater were up to 0.790 and 0.427 ng/L in dry and wet seasons, respectively, though no significant seasonal variation was observed. Spatially, the Deep Bay Water Control Zone was the most enriched area with the studied compounds owing to its semi-enclosed nature and influence from the Pearl River discharge. During algal blooms, the studied compounds were detected up to 4.74 ng/L. Based on calculated risk quotients, the ecological risk of the studied compounds to Hong Kong's marine ecosystems was low. Nevertheless, the occurrence and distribution of these chemicals in the marine environment should be closely monitored where algal blooms frequently occur.
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Affiliation(s)
- Katie Wan Yee Yeung
- State Key Laboratory of Marine Pollution and Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China; The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Kevin King Yan Ho
- The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Guang-Jie Zhou
- State Key Laboratory of Marine Pollution and Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China; The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China.
| | - Yuefei Ruan
- State Key Laboratory of Marine Pollution and Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China; Research Centre for the Oceans and Human Health, City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519080, China
| | - Paul Kwan Sing Lam
- State Key Laboratory of Marine Pollution and Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China; Research Centre for the Oceans and Human Health, City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519080, China; Office of the President, Hong Kong Metropolitan University, Hong Kong, China
| | - Kenneth Mei Yee Leung
- State Key Laboratory of Marine Pollution and Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519080, China.
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Study of ALDH from Thermus thermophilus-Expression, Purification and Characterisation of the Non-Substrate Specific, Thermophilic Enzyme Displaying Both Dehydrogenase and Esterase Activity. Cells 2021; 10:cells10123535. [PMID: 34944041 PMCID: PMC8699947 DOI: 10.3390/cells10123535] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/10/2021] [Accepted: 12/11/2021] [Indexed: 01/16/2023] Open
Abstract
Aldehyde dehydrogenases (ALDH), found in all kingdoms of life, form a superfamily of enzymes that primarily catalyse the oxidation of aldehydes to form carboxylic acid products, while utilising the cofactor NAD(P)+. Some superfamily members can also act as esterases using p-nitrophenyl esters as substrates. The ALDHTt from Thermus thermophilus was recombinantly expressed in E. coli and purified to obtain high yields (approximately 15–20 mg/L) and purity utilising an efficient heat treatment step coupled with IMAC and gel filtration chromatography. The use of the heat treatment step proved critical, in its absence decreased yield of 40% was observed. Characterisation of the thermophilic ALDHTt led to optimum enzymatic working conditions of 50 °C, and a pH of 8. ALDHTt possesses dual enzymatic activity, with the ability to act as a dehydrogenase and an esterase. ALDHTt possesses broad substrate specificity, displaying activity for a range of aldehydes, most notably hexanal and the synthetic dialdehyde, terephthalaldehyde. Interestingly, para-substituted benzaldehydes could be processed efficiently, but ortho-substitution resulted in no catalytic activity. Similarly, ALDHTt displayed activity for two different esterase substrates, p-nitrophenyl acetate and p-nitrophenyl butyrate, but with activities of 22.9% and 8.9%, respectively, compared to the activity towards hexanal.
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6
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Miles JA, Egan JL, Fowler JA, Machattou P, Millard AD, Perry CJ, Scanlan DJ, Taylor PC. The evolutionary origins of peroxynitrite signalling. Biochem Biophys Res Commun 2021; 580:107-112. [PMID: 34638028 DOI: 10.1016/j.bbrc.2021.09.071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/24/2021] [Accepted: 09/25/2021] [Indexed: 12/13/2022]
Abstract
Peroxynitrite is a reactive intermediate formed in vivo through uncatalysed reaction of superoxide and nitric oxide radicals. Despite significant interest in detecting peroxynitrite in vivo and understanding its production, little attention has been given to the evolutionary origins of peroxynitrite signalling. Herein we focus on two enzymes that are key to the biosynthesis of superoxide and nitric oxide, NADPH oxidase 5 (NOX5) and endothelial nitric oxide synthase (eNOS), respectively. Multiple sequence alignments of both enzymes including homologues from all domains of life, coupled with a phylogenetic analysis of NOX5, suggest eNOS and NOX5 are present in animals as the result of horizontal gene transfer from ancestral cyanobacteria to ancestral eukaryotes. Therefore, biochemical studies from other laboratories on a NOX5 homologue in Cylindrospermum stagnale and an eNOS homologue in Synechococcus sp. PCC 7335 are likely to be of relevance to human NOX5 and eNOS and to the production of superoxide, nitric oxide and peroxynitrite in humans.
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Affiliation(s)
- Jennifer A Miles
- School of Chemistry & Astbury Centre, University of Leeds, Leeds, LS2 9JT, UK
| | - Joseph L Egan
- School of Chemistry & Astbury Centre, University of Leeds, Leeds, LS2 9JT, UK
| | - Jake A Fowler
- School of Chemistry & Astbury Centre, University of Leeds, Leeds, LS2 9JT, UK
| | - Petrina Machattou
- School of Chemistry & Astbury Centre, University of Leeds, Leeds, LS2 9JT, UK
| | - Andrew D Millard
- Dept. of Genome Biology & Genetics, University of Leicester, Leicester, LE1 7RH, UK
| | | | - David J Scanlan
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Paul C Taylor
- School of Chemistry & Astbury Centre, University of Leeds, Leeds, LS2 9JT, UK.
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Miles JA, Davies TA, Hayman RD, Lorenzen G, Taylor J, Anjarwalla M, Allen SJR, Graham JWD, Taylor PC. A Case Study of Eukaryogenesis: The Evolution of Photoreception by Photolyase/Cryptochrome Proteins. J Mol Evol 2020; 88:662-673. [PMID: 32979052 PMCID: PMC7560933 DOI: 10.1007/s00239-020-09965-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 09/05/2020] [Indexed: 11/23/2022]
Abstract
Eukaryogenesis, the origin of the eukaryotes, is still poorly understood. Herein, we show how a detailed all-kingdom phylogenetic analysis overlaid with a map of key biochemical features can provide valuable clues. The photolyase/cryptochrome family of proteins are well known to repair DNA in response to potentially harmful effects of sunlight and to entrain circadian rhythms. Phylogenetic analysis of photolyase/cryptochrome protein sequences from a wide range of prokaryotes and eukaryotes points to a number of horizontal gene transfer events between ancestral bacteria and ancestral eukaryotes. Previous experimental research has characterised patterns of tryptophan residues in these proteins that are important for photoreception, specifically a tryptophan dyad, a canonical tryptophan triad, an alternative tryptophan triad, a tryptophan tetrad and an alternative tetrad. Our results suggest that the spread of the different triad and tetrad motifs across the kingdoms of life accompanied the putative horizontal gene transfers and is consistent with multiple bacterial contributions to eukaryogenesis.
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Affiliation(s)
- Jennifer A Miles
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Thomas A Davies
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Robert D Hayman
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Georgia Lorenzen
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Jamie Taylor
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Mubeena Anjarwalla
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Sammie J R Allen
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - John W D Graham
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Paul C Taylor
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.
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Yeung KWY, Zhou GJ, Hilscherová K, Giesy JP, Leung KMY. Current understanding of potential ecological risks of retinoic acids and their metabolites in aquatic environments. ENVIRONMENT INTERNATIONAL 2020; 136:105464. [PMID: 31926435 DOI: 10.1016/j.envint.2020.105464] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 12/13/2019] [Accepted: 01/02/2020] [Indexed: 06/10/2023]
Abstract
In animals, retinoic acids (RAs), one of the main derivatives of vitamin A, are crucial for a variety of physiological processes. RAs, including all-trans-RA, 9-cis-RA, 13-cis-RA, and their corresponding metabolites (i.e., all-trans-4-oxo-RA, 9-cis-4-oxo-RA and 13-cis-4-oxo-RA) can be excreted through urination from humans and animals. Sewage treatment plants (STPs) are a significant source of RAs and 4-oxo-RAs into aquatic environments. RAs and 4-oxo-RAs can be identified and quantified by use of liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). RAs and 4-oxo-RAs have been reported in various environmental matrices including rivers, lakes, reservoirs and coastal marine environments as well as in sewage effluents discharged from STPs. Greater concentrations of RAs and 4-oxo-RAs have been observed during blooms of cyanobacteria and microalgae, suggesting that cyanobacteria and microalgae are natural sources of RAs and 4-oxo-RAs in aquatic environments. These potential sources of RAs and 4-oxo-RAs raise concerns about their concentrations and risks in aquatic environments because excessive intake of these chemicals can result in abnormal morphological development in animals. Teratogenic effects were observed in amphibians, fish embryos, gastropods, mammals and birds when exposed to RAs. This review summarizes sources, concentrations, adverse effects and ecological risks of RAs and 4-oxo-RAs in aquatic environments. An interim, predicted no-effect concentration (PNEC) of RAs (in terms of at-RA) for freshwater environments was determined to be 3.93 ng/L at-RA equivalents. Based on limited data on concentrations of RAs in freshwater ecosystems, their hazard quotients were found to range from zero to 16.41, depending on the environmental conditions of receiving waters. Ecological risks of RAs in marine environments are yet to be explored due to the paucity of data related to both their concentrations in marine environment and toxic potencies to marine species. This review updates current knowledge of RAs and 4-oxo-RAs in aquatic environments and calls for more studies on their concentrations and fate in aquatic environments, especially estuarine and coastal marine environments with a view to enabling a comprehensive assessment of their ecological risks around the globe.
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Affiliation(s)
- Katie Wan Yee Yeung
- The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Guang-Jie Zhou
- The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China.
| | - Klára Hilscherová
- RECETOX, Faculty of Science, Masaryk University, Kamenice 753/5, Pavilion A29, 625 00 Brno, Czech Republic
| | - John P Giesy
- Department of Veterinary Biomedical Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada; Department of Environmental Science, Baylor University, Waco, TX, United States
| | - Kenneth Mei Yee Leung
- The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China; State Key Laboratory of Marine Pollution (City University of Hong Kong), Tat Chee Avenue, Kowloon, Hong Kong, China.
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Llewellyn CA, Airs RL, Farnham G, Greig C. Synthesis, Regulation and Degradation of Carotenoids Under Low Level UV-B Radiation in the Filamentous Cyanobacterium Chlorogloeopsis fritschii PCC 6912. Front Microbiol 2020; 11:163. [PMID: 32117174 PMCID: PMC7029182 DOI: 10.3389/fmicb.2020.00163] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 01/23/2020] [Indexed: 11/23/2022] Open
Abstract
Carotenoids in cyanobacteria play an important role in protecting against and in repairing damage against low level UV-B radiation. Here we use transcriptomics and metabolomic HPLC pigment analysis to compare carotenoid pathway regulation in the filamentous cyanobacterium Chlorogloeopsis fritschii PCC 6912 exposed to white light and to white light supplemented with low level UV-B. Under UV-B changes in carotenoid transcription regulation were found associated with carotenogenesis (carotenoid synthesis), photoprotection and carotenoid cleavage. Transcriptional regulation was reflected in corresponding pigment signatures. All carotenogenesis pathway genes from geranylgeranyl-diphosphate to lycopene were upregulated. There were significant increases in expression of gene homologs (crtW, crtR, cruF, and cruG) associated with routes to ketolation to produce significant increases in echinenone and canthaxanthin concentrations. There were gene homologs for four β-carotene-ketolases (crtO and crtW) present but only one crtW was upregulated. Putative genes encoding enzymes (CruF, CrtR, and CruG) for the conversion of γ-carotene to myxol 2'-methylpentoside were upregulated. The hydroxylation pathway to nostaxanthin via zeaxanthin and caloxanthin (gene homologs for CrtR and CrtG) were not upregulated, reflected in the unchanged corresponding pigment concentrations in zeaxanthin, caloxanthin and nostaxanthin, Transcripts for the non-photochemical quenching related Orange-Carotenoid-Protein (OCP) and associated Fluoresence-Recovery-Protein (FRP) associated with photoprotection were upregulated, and one carotenoid binding Helical-Carotenoid-Protein (HCP) gene homolog was downregulated. Multiple copies of genes encoding putative apocarotenoid related carotenoid oxygenases responsible for carotenoid cleavage were identified, including an upregulated apo-β-carotenal-oxygenase gene homologous to a retinal producing enzyme. Our study provides holistic insight into the photoregulatory processes that modulate the synthesis, photoprotection and cleavage of carotenoids in cyanobacterial cells exposed to low level UV-B. This is important to understanding how regulation of metabolism responds to a changing environment and how metabolism can be modulated for biotechnological purposes.
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Affiliation(s)
- Carole A. Llewellyn
- Department of Biosciences, College of Science, Swansea University, Swansea, United Kingdom
| | - Ruth L. Airs
- Plymouth Marine Laboratory, Plymouth, United Kingdom
| | - Garry Farnham
- Faculty of Medicine and Dentistry, University of Plymouth, Plymouth, United Kingdom
| | - Carolyn Greig
- Department of Biosciences, College of Science, Swansea University, Swansea, United Kingdom
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