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Ito-Harashima S, Tsubouchi Y, Takada E, Kawanishi M, Yagi T. Development of a yeast reporter gene assay to detect ligands of freshwater cladoceran Daphnia magna ultraspiracle, a homolog of vertebrate retinoid X receptors. J Appl Toxicol 2023; 43:1447-1461. [PMID: 37078133 DOI: 10.1002/jat.4476] [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: 10/01/2022] [Revised: 04/16/2023] [Accepted: 04/17/2023] [Indexed: 04/21/2023]
Abstract
Endocrine-disrupting chemicals (EDCs) often affect homeostatic regulation in living organisms by directly acting on nuclear receptors (NRs). Retinoid X receptors (RXRs), the most highly conserved members of the NR superfamily during evolution, function as partners to form heterodimers with other NRs, such as retinoic acid, thyroid hormone, and vitamin D3 receptors. RXRs also homodimerize and induce the expression of target genes upon binding with their natural ligand, 9-cis-retinoic acid (9cRA), and typical EDCs organotin compounds, such as tributyltin and triphenyltin. In the present study, we established a new yeast reporter gene assay (RGA) to detect the ligands of freshwater cladoceran Daphnia magna ultraspiracle (Dapma-USP), a homolog of vertebrate RXRs. D. magna has been used as a representative crustacean species for aquatic EDC assessments in the Organization for Economic Corporation and Development test guidelines. Dapma-USP was expressed along with the Drosophila melanogaster steroid receptor coactivator Taiman in yeast cells carrying the lacZ reporter plasmid. The RGA for detecting agonist activity of organotins and o-butylphenol was improved by use of mutant yeast strains lacking genes encoding cell wall mannoproteins and/or plasma membrane drug efflux pumps as hosts. We also showed that a number of other human RXR ligands, phenol and bisphenol A derivatives, and terpenoid compounds such as 9c-RA exhibited antagonist activity on Dapma-USP. Our newly established yeast-based RGA system is valuable as the first screening tool to detect ligand substances for Dapma-USP and for evaluating the evolutionary divergence of the ligand responses of RXR homologs between humans and D. magna.
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Affiliation(s)
- Sayoko Ito-Harashima
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
- Department of Applied Biological Chemistry, Graduate School of Agriculture, Osaka Metropolitan University, Sakai, Japan
| | - Yumiko Tsubouchi
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
| | - Eiji Takada
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
| | - Masanobu Kawanishi
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
- Department of Biological Chemistry, Graduate School of Science, Osaka Metropolitan University, Sakai, Japan
| | - Takashi Yagi
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
- Department of Biological Chemistry, Graduate School of Science, Osaka Metropolitan University, Sakai, Japan
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Feng Y, Cui J, Jin B, Li X, Zhang X, Liu L, Zhang L. In Vitro Binding Effects of the Ecdysone Receptor-Binding Domain and PonA in Plutella xylostella. Molecules 2023; 28:molecules28031426. [PMID: 36771090 PMCID: PMC9920912 DOI: 10.3390/molecules28031426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/27/2023] [Accepted: 01/30/2023] [Indexed: 02/05/2023] Open
Abstract
Both insect ecdysone receptors and ultraspiracle belong to the nuclear receptor family. They form a nanoscale self-assembling complex with ecdysteroids in cells, transit into the nucleus, bind with genes to initiate transcription, and perform specific biological functions to regulate the molting, metamorphosis, and growth processes of insects. Therefore, this complex is an important target for the development of eco-friendly insecticides. The diamondback moth (Plutella xylostella) is a devastating pest of cruciferous vegetable crops, wreaking havoc worldwide and causing severe economic losses, and this pest has developed resistance to most chemical insecticides. In this study, highly pure EcR and USP functional domains were obtained by constructing a prokaryotic expression system for the diamondback moth EcR and USP functional domain genes, and the differences between EcR and USP binding domain monomers and dimers were analyzed using transmission electron microscopy and zeta potential. Radioisotope experiments further confirmed that the binding affinity of PonA to the EcR/USP dimer was enhanced approximately 20-fold compared with the binding affinity to the PxGST-EcR monomer. The differences between PonA and tebufenozide in binding with EcR/USP were examined. Molecular simulations showed that the hydrogen bonding network formed by Glu307 and Arg382 on the EcR/USP dimer was a key factor in the affinity enhancement. This study provides a rapid and sensitive method for screening ecdysone agonists for ecdysone receptor studies in vitro.
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Affiliation(s)
- Yanjiao Feng
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China
| | - Jialin Cui
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China
| | - Binyan Jin
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China
| | - Xiuzhen Li
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China
| | - Xiaoming Zhang
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China
| | - Libing Liu
- Department of Nutrition and Health, China Agricultural University, Beijing 100193, China
- Correspondence: (L.L.); (L.Z.)
| | - Li Zhang
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China
- Correspondence: (L.L.); (L.Z.)
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Yokoi T, Nabe T, Ishizuka C, Hayashi K, Ito-Harashima S, Yagi T, Nakagawa Y, Miyagawa H. A luciferase reporter assay for ecdysone agonists using HEK293T cells. Biosci Biotechnol Biochem 2022; 86:1490-1496. [PMID: 35977393 DOI: 10.1093/bbb/zbac139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 08/10/2022] [Indexed: 11/12/2022]
Abstract
Ecdysone agonists are a class of insecticides that activate the ecdysone receptor (EcR) heterodimerized with the ultraspiracle (USP). Here, we report a new luciferase reporter assay for ecdysone agonists. The assay employs mammalian HEK293T cells transiently transfected with the EcR and USP genes of Chilo suppressalis, along with the taiman (Tai) gene of Drosophila melanogaster that encodes a steroid receptor coactivator. This assay system gave results consistent with those of radioligand binding assays and showed sensitivity superior to that of the existing in vitro methods. In addition, use of the heterologous host cells precludes perturbation from intrinsic players of the ecdysone signaling, which is a potential drawback of insect cell-based methods. This reporter system is suitable for detailed structure-activity analysis of ecdysone agonists and will serve as a valuable tool for the rational design of novel insect growth regulators.
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Affiliation(s)
- Taiyo Yokoi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, Japan
| | - Taku Nabe
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, Japan
| | - Chiharu Ishizuka
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, Japan
| | - Ken'ichiro Hayashi
- Department of RNA Biology and Neuroscience, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka, Japan.,Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi, Japan
| | - Sayoko Ito-Harashima
- Department of Applied Biological Chemistry, Graduate School of Agriculture, Osaka Metropolitan University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka, Japan
| | - Takashi Yagi
- Department of Biological Chemistry, Graduate School of Science, Osaka Metropolitan University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka, Japan
| | - Yoshiaki Nakagawa
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, Japan
| | - Hisashi Miyagawa
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, Japan
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Pandey AK, Sharma V, Ravi Ram K. Drosophila ecdysone receptor activity-based ex vivo assay to assess the endocrine disruption potential of environmental chemicals. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:56430-56441. [PMID: 35338461 DOI: 10.1007/s11356-022-19789-5] [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: 12/03/2021] [Accepted: 03/14/2022] [Indexed: 06/14/2023]
Abstract
Insect pollinators, critical for both agricultural output and the ecosystem, are declining at an alarming levels partly due to human-made chemicals. Majority of environmental chemicals hamper the endocrine function and studies on the same in insects remain neglected. Here, we report a Drosophila-based ex vivo assay system that employs a reproductive tissue from transgenic males carrying a reporter gene (lacZ) downstream of ecdysone receptor response element (EcRE) and permits the evaluation of chemical-mediated activity modulation of all three isoforms of ecdysone receptor, which are critical for male fertility. We show agonistic [plasticizers, cypermethrin, atrazine, methyl parathion, imidacloprid, cadmium chloride, mercuric chloride or 3-(4-methylbenzylidene) camphor] or antagonistic (apigenin, tributyltin chloride) effects or lack of effect thereof (rutin hydrate, dichlorvos, lead acetate, parabens) for seven different classes of environmental chemicals on ecdysone receptor activity reflecting the specificity and sensitivity of the developed ex vivo assay. Exposure to a few of these chemicals in vivo hampers the fertility of Drosophila males, thus linking the observed endocrine disruption to a quantifiable reproductive phenotype. The developed ex vivo assay offers a quick Drosophila-based screening tool for throughput monitoring of environmental chemicals for their ability to hamper the endocrine function of insect pollinators and other invertebrates.
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Affiliation(s)
- Anuj Kumar Pandey
- Embryotoxicology Laboratory, Environmental Toxicology Group, CSIR- Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhavan, 31, Mahatma Gandhi Marg, Lucknow, 226001, Uttar Pradesh, India
- Department of Respiratory Medicine, King George's Medical University, Lucknow, 226003, Uttar Pradesh, India
| | - Vandana Sharma
- Embryotoxicology Laboratory, Environmental Toxicology Group, CSIR- Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhavan, 31, Mahatma Gandhi Marg, Lucknow, 226001, Uttar Pradesh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad , 201002, India
| | - Kristipati Ravi Ram
- Embryotoxicology Laboratory, Environmental Toxicology Group, CSIR- Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhavan, 31, Mahatma Gandhi Marg, Lucknow, 226001, Uttar Pradesh, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad , 201002, India.
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Ito-Harashima S, Matsuura M, Takada E, Kawanishi M, Nakagawa Y, Yagi T. Detection of juvenile hormone agonists by a new reporter gene assay using yeast expressing Drosophila methoprene-tolerant. FEBS Open Bio 2021; 11:2774-2783. [PMID: 34407562 PMCID: PMC8487040 DOI: 10.1002/2211-5463.13277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 07/18/2021] [Accepted: 08/18/2021] [Indexed: 12/26/2022] Open
Abstract
Juvenile hormones (JHs) are sesquiterpenoids that play important roles in the regulation of growth, metamorphosis, and reproduction in insects. Synthetic JH agonists (JHAs) have been used as insecticides and are categorized as a class of insect growth regulators (IGRs). Natural JHs and synthetic JHAs bind to the JH receptor methoprene‐tolerant (Met), which forms a functional JH‐receptor complex with steroid receptor coactivators, such as Drosophila melanogaster Taiman (Tai). The ligand‐bound Met–Tai complex induces the transcription of JH response genes by binding to specific DNA elements referred to as JH response elements (JHREs). In the present study, we established a reporter gene assay (RGA) for detecting natural JHs and synthetic JHAs in a yeast strain expressing D. melanogaster Met and Tai. The yeast RGA system detected various juvenoid ligands in a dose‐dependent manner. The rank order of the ligand potencies of the juvenoids examined in the yeast RGA linearly correlated with those of RGAs for Met–Tai established in mammalian and insect cells. Our new yeast RGA is rapid, easy to handle, cost‐effective, and valuable for screening novel JHAs.
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Affiliation(s)
- Sayoko Ito-Harashima
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
| | - Mai Matsuura
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
| | - Eiji Takada
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
| | - Masanobu Kawanishi
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
| | - Yoshiaki Nakagawa
- Division of Applied Science, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Japan
| | - Takashi Yagi
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
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Ito-Harashima S, Yagi T. Reporter gene assays for screening and identification of novel molting hormone- and juvenile hormone-like chemicals. JOURNAL OF PESTICIDE SCIENCE 2021; 46:29-42. [PMID: 33746544 PMCID: PMC7953021 DOI: 10.1584/jpestics.d20-079] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 12/23/2020] [Indexed: 06/12/2023]
Abstract
A reporter gene assay (RGA) is used to investigate the activity of synthetic chemicals mimicking the molting hormones (MHs) and juvenile hormones (JHs) of insects, so-called insect growth regulators (IGRs). The MH receptor, a heterodimer of the ecdysone receptor (EcR) and ultraspiracle (USP), and the JH receptor Methoprene-tolerant (Met) are ligand-dependent transcription factors. Ligand-bound EcR-USP and Met bind to specific cis-acting DNA elements, referred to as the ecdysone-responsive element (EcRE) and the JH-responsive element (JHRE), respectively, in order to transactivate target genes. Insect hormone-induced transactivation systems have been reconstituted by the introduction of reporter genes under the control of EcRE and JHRE, or two-hybrid reporter genes, into insect, mammalian, and yeast cells expressing receptor proteins. RGA is easy to use and convenient for examining the MH- and JH-like activities of synthetic chemicals and is suitable for the high-throughput screening of novel structural classes of chemicals targeting EcR-USP and Met.
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Affiliation(s)
- Sayoko Ito-Harashima
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1–1 Gakuen-cho, Naka-ku, Sakai city, Osaka 599–8531, Japan
| | - Takashi Yagi
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1–1 Gakuen-cho, Naka-ku, Sakai city, Osaka 599–8531, Japan
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Yokoi T, Nabe T, Ishizuka C, Hayashi K, Ito-Harashima S, Yagi T, Nakagawa Y, Miyagawa H. Transcription-inducing activity of natural and synthetic juvenile hormone agonists through the Drosophila Methoprene-tolerant protein. PEST MANAGEMENT SCIENCE 2020; 76:2316-2323. [PMID: 32003111 DOI: 10.1002/ps.5766] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 01/15/2020] [Accepted: 01/30/2020] [Indexed: 06/10/2023]
Abstract
BACKGROUND Juvenile hormones (JHs) are a class of sesquiterpenoids that play a pivotal role in insect growth and reproduction. Synthetic JH agonists (JHAs), including pyriproxyfen, have been widely used as insecticides to control agricultural pests and disease vectors. The antimetamorphic action of JHAs is mediated by their intracellular receptor, the heterodimer of Methoprene-tolerant (Met) and Taiman (Tai) proteins. Although a range of bioassay systems has been developed to detect the activity of JHAs, each of these systems has its own drawback(s), such as poor reproducibility, the use of radioactive ligands or the effect of endogenous JH-signaling factors. RESULTS To address these issues, we constructed a new luciferase reporter assay for JHAs in mammalian HEK293T cells transiently transfected with the Drosophila Met and Tai genes. This reporter system gave highly reproducible results and showed nanomolar sensitivity to natural JHs. We then applied this reporter system to a structure-activity relationship (SAR) analysis of 14 natural and synthetic JHAs, leading to identification of the ligand structural factors important for the transcription-inducing activity. CONCLUSION Because this reporter system is not affected by the signaling cascade downstream of the JH receptors, it is suitable for evaluating the intrinsic activity of JHAs. The SAR results obtained in this study therefore provide invaluable information on the rational design of novel JHA insecticides.
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Affiliation(s)
- Taiyo Yokoi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Taku Nabe
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Chiharu Ishizuka
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Ken'ichiro Hayashi
- Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Sayoko Ito-Harashima
- Department of Biology, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
| | - Takashi Yagi
- Department of Biology, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
| | - Yoshiaki Nakagawa
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Hisashi Miyagawa
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
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Ito-Harashima S, Matano M, Onishi K, Nomura T, Nakajima S, Ebata S, Shiizaki K, Kawanishi M, Yagi T. Construction of reporter gene assays using CWP and PDR mutant yeasts for enhanced detection of various sex steroids. Genes Environ 2020; 42:20. [PMID: 32514322 PMCID: PMC7251871 DOI: 10.1186/s41021-020-00159-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 05/16/2020] [Indexed: 12/21/2022] Open
Abstract
Background Sex steroid hormone receptors are classified into three classes of receptors: estrogen receptors (ER) α and β, androgen receptor (AR), and progesterone receptor (PR). They belong to the nuclear receptor superfamily and activate their downstream genes in a ligand-dependent manner. Since sex steroid hormones are involved in a wide variety of physiological processes and cancer development, synthetic chemical substances that exhibit sex steroid hormone activities have been applied as pharmaceuticals and consumed in large amounts worldwide. They are potentially hazardous contaminants as endocrine disruptors in the environment because they may induce inappropriate gene expression mediated by sex steroid hormone receptors in vivo. Results To develop simple reporter gene assays with enhanced sensitivity for the detection of sex steroid hormones, we newly established mutant yeast strains lacking the CWP and PDR genes encoding cell wall mannoproteins and plasma membrane drug efflux pumps, respectively, and expressing human ERα, ERβ, AR, and PR. Reporter gene assays with mutant yeast strains responded to endogenous and synthetic ligands more strongly than those with wild-type strains. Sex steroid hormone activities in some pharmaceutical oral tablets and human urine were also detectable in these yeast assays. Conclusions Yeast reporter gene assay systems for all six steroid hormone receptors, including previously established glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) assay yeasts, are now available. Environmental endocrine disrupters with steroid hormone activity will be qualitatively detectable by simple and easy procedures. The yeast-based reporter gene assay will be valuable as a primary screening tool to detect and evaluate steroid hormone activities in various test samples. Our assay system will strongly support the detection of agonists, antagonists, and inverse agonists of steroid hormone receptors in the field of novel drug discovery and assessments of environmental pollutants.
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Affiliation(s)
- Sayoko Ito-Harashima
- Department of Biological Sciences, Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8570 Japan
| | - Mami Matano
- Department of Biological Sciences, Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8570 Japan
| | - Kana Onishi
- Department of Biological Sciences, Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8570 Japan
| | - Tomofumi Nomura
- Department of Biological Sciences, Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8570 Japan
| | - Saki Nakajima
- Department of Biological Sciences, Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8570 Japan
| | - Shingo Ebata
- Department of Biological Sciences, Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8570 Japan
| | - Kazuhiro Shiizaki
- Department of Biological Sciences, Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8570 Japan.,Present address: Department of Applied Biosciences, Graduate School of Life Sciences, Toyo University, 1-1-1 Izumino, Itakura-machi, Ora-gun, Gunma 374-0193 Japan
| | - Masanobu Kawanishi
- Department of Biological Sciences, Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8570 Japan
| | - Takashi Yagi
- Department of Biological Sciences, Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8570 Japan
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