1
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Lv JL, Lai WQ, Gong YQ, Zheng KY, Zhang XY, Wang XY, Dai LS, Li MW. Studying the role of Bombyx mori molybdenum cofactor sulfurase in Bombyx mori nucleopolyhedrovirus infection. INSECT MOLECULAR BIOLOGY 2024; 33:246-258. [PMID: 38323672 DOI: 10.1111/imb.12895] [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: 08/24/2023] [Accepted: 01/10/2024] [Indexed: 02/08/2024]
Abstract
Molybdenum cofactor sulfurase (MoCoS) is a key gene involved in the uric acid metabolic pathway that activates xanthine dehydrogenase to synthesise uric acid. Uric acid is harmful to mammals but plays crucial roles in insects, one of which is the immune responses. However, the function of Bombyx mori MoCoS in response to BmNPV remains unclear. In this study, BmMoCoS was found to be relatively highly expressed in embryonic development, gonads and the Malpighian tubules. In addition, the expression levels of BmMoCoS were significantly upregulated in three silkworm strains with different levels of resistance after virus infection, suggesting a close link between them. Furthermore, RNAi and overexpression studies showed that BmMoCoS was involved in resistance to BmNPV infection, and its antivirus effects were found to be related to the regulation of uric acid metabolism, which was uncovered by inosine- and febuxostat-coupled RNAi and overexpression. Finally, the BmMoCoS-mediated uric acid pathway was preliminarily confirmed to be a potential target to protect silkworms from BmNPV infection. Overall, this study provides new evidence for elucidating the molecular mechanism of silkworms in response to BmNPV infection and new strategies for the prevention of viral infections in sericulture.
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Affiliation(s)
- Jun-Li Lv
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
| | - Wen-Qing Lai
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
| | - Yu-Quan Gong
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
| | - Kai-Yi Zheng
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
| | - Xiao-Ying Zhang
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
| | - Xue-Yang Wang
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
- The Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture, Sericultural Research Institute, Chinese Academy of Agricultural Science, Zhenjiang, Jiangsu, China
| | - Li-Shang Dai
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Mu-Wang Li
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
- The Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture, Sericultural Research Institute, Chinese Academy of Agricultural Science, Zhenjiang, Jiangsu, China
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2
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Tang L, Chen D, Yang D, Liu Z, Yang X, Liu Y, Zhang L, Liu Z, Wang Y, Tang Z, Huang Y. Bmpali, Bmb1 and Bmcap are necessary for uric acid granule formation in Bombyx mori. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2024; 167:104075. [PMID: 38278280 DOI: 10.1016/j.ibmb.2024.104075] [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: 11/22/2023] [Revised: 01/15/2024] [Accepted: 01/15/2024] [Indexed: 01/28/2024]
Abstract
Uric acid is the end-product of nitrogen metabolism of the silkworm and other lepidopterans. The accumulation of uric acid particles in the epidermis causes the larval silkworm to appear white and opaque. However, the mechanism of uric acid granule formation is still unclear. Silkworm epidermis color is linked to the genes responsible for uric acid particle formation. We first identified two genes in the Bombyx mori genome that encode subunits of the Bloc-1 (Biogenesis of Lysosome-related Organelles Complex-1) by homology to these genes in other eukaryotes, Bmpali and Bmb1. Mutation in these genes caused a transparent phenotype in the silkworm larvae, and the loss of BmBloc-1 subunit gene Bmcap resulted in the same phenotype. These three genes are highly conserved between human and silkworm. We discovered that Bmpali, Bmcap, and Bmb1 localize in the cytoplasm of BmN cells. Yeast two-hybrid assays demonstrated that the Bmpali physically interacts with both Bmcap and Bmb1. Investigating the roles of Bmpali, Bmb1, and Bmcap is essential for uric acid granule formation understanding in Bombyx mori. These mutants present a valuable silkworm model for studying the biogenesis of lysosome-related organelles (LROs).
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Affiliation(s)
- Linmeng Tang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China; Central Research Institute, Shanghai Pharmaceuticals Holding Co., Ltd., Shanghai, China
| | - Dongbin Chen
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Dehong Yang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Zhiwei Liu
- Departments of Neonatology, International Peace Maternity and Child Health Hospital of China Welfare Institution, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xu Yang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Yujia Liu
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Liying Zhang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Zulian Liu
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Yaohui Wang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Zheng Tang
- Departments of Neonatology, International Peace Maternity and Child Health Hospital of China Welfare Institution, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
| | - Yongping Huang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China.
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3
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Tang L, Yang D, Liu Z, Wang Y, Yang X, Liu Y, Chen D, Tang Z, Huang Y. Functional characterization of Bmcap in uric acid metabolism in the silkworm. INSECT SCIENCE 2024; 31:147-156. [PMID: 37358054 DOI: 10.1111/1744-7917.13236] [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: 11/24/2022] [Revised: 04/13/2023] [Accepted: 05/13/2023] [Indexed: 06/27/2023]
Abstract
After a millennium of domestication, numerous silkworm mutants have emerged that exhibit transparent epidermis, which is caused by abnormally low levels of uric acid. We identified the Bombyx mori gene Bmcap (BMSK0003832) as the homolog of cappuccino, a subunit of the biogenesis of lysosome-related organelles complex-1 (BLOC-1) that has been extensively characterized in human, mouse, and insect species, by analyzing the amino acid sequences of putative purine metabolism genes. Using the clustered regularly interspaced palindromic repeats (CRISPR) / CRISPR-associated protein 9 system, we disrupted Bmcap, resulting in decreased uric acid levels in the silkworm epidermis and a translucent skin phenotype. In the Bmcap mutant, the purine metabolism, nitrogen metabolism, pyrimidine metabolism, and membrane system were altered compared to the wild type. Biogenesis of lysosome-related organelle complex genes play a role in the pigmentation and biogenesis of lysosome-related organelles (LROs) in platelets, melanocytes, and megakaryocytes. LROs exhibit unique morphologies and functions in various tissues and cells. Investigation of the Bmcap mutant will enhance our understanding of the uric acid metabolic pathway in silkworms, and this mutant offers a valuable silkworm model for LRO studies.
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Affiliation(s)
- Linmeng Tang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
- Central Research Institute, Shanghai Pharmaceuticals Holding Co., Ltd., Shanghai, China
| | - Dehong Yang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Zhiwei Liu
- Departments of Neonatology, International Peace Maternity and Child Health Hospital of China Welfare Institution, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yaohui Wang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Xu Yang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Yujia Liu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Dongbin Chen
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Zheng Tang
- Departments of Neonatology, International Peace Maternity and Child Health Hospital of China Welfare Institution, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yongping Huang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
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4
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Fu X, Chen M, Xia R, Li X, Li Q, Li Y, Cao H, Liu Y. Genome-Wide Identification and Transcriptome-Based Expression Profile of Cuticular Protein Genes in Antheraea pernyi. Int J Mol Sci 2023; 24:ijms24086991. [PMID: 37108155 PMCID: PMC10138643 DOI: 10.3390/ijms24086991] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 03/27/2023] [Accepted: 04/03/2023] [Indexed: 04/29/2023] Open
Abstract
Antheraea pernyi is one of the most famous edible and silk-producing wild silkworms of Saturniidae. Structural cuticular proteins (CPs) are the primary component of insect cuticle. In this paper, the CPs in the genome of A. pernyi were identified and compared with those of the lepidopteran model species Bombyx mori, and expression patterns were analyzed based on the transcriptomic data from the larval epidermis/integument (epidermis in the following) and some non-epidermis tissues/organs of two silkworm species. A total of 217 CPs was identified in the A. pernyi genome, a comparable number to B. mori (236 CPs), with CPLCP and CPG families being the main contribution to the number difference between two silkworm species. We found more RR-2 genes expressed in the larval epidermis of fifth instar of A. pernyi than B. mori, but less RR-2 genes expressed in the prothoracic gland of A. pernyi than B. mori, which suggests that the hardness difference in the larval epidermis and prothoracic gland between the two species may be caused by the number of RR-2 genes expressed. We also revealed that, in B. mori, the number of CP genes expressed in the corpus allatum and prothoracic gland of fifth instar was higher than that in the larval epidermis. Our work provided an overall framework for functional research into the CP genes of Saturniidae.
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Affiliation(s)
- Xin Fu
- College of Bioscience and Biotechnology, Shenyang Agricultural University, 120 Dongling Road, Shenyang 110866, China
| | - Miaomiao Chen
- Research Group of Silkworm Breeding, Sericultural Institute of Liaoning Province, Liaoning Academy of Agricultural Sciences, 108 Fengshan Road, Fengcheng 118100, China
| | - Runxi Xia
- College of Bioscience and Biotechnology, Shenyang Agricultural University, 120 Dongling Road, Shenyang 110866, China
| | - Xinyu Li
- College of Bioscience and Biotechnology, Shenyang Agricultural University, 120 Dongling Road, Shenyang 110866, China
| | - Qun Li
- College of Bioscience and Biotechnology, Shenyang Agricultural University, 120 Dongling Road, Shenyang 110866, China
| | - Yuping Li
- College of Bioscience and Biotechnology, Shenyang Agricultural University, 120 Dongling Road, Shenyang 110866, China
| | - Huiying Cao
- College of Bioscience and Biotechnology, Shenyang Agricultural University, 120 Dongling Road, Shenyang 110866, China
| | - Yanqun Liu
- College of Bioscience and Biotechnology, Shenyang Agricultural University, 120 Dongling Road, Shenyang 110866, China
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5
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Kawamoto M, Kiuchi T, Katsuma S. SilkBase: an integrated transcriptomic and genomic database for Bombyx mori and related species. Database (Oxford) 2022; 2022:6603636. [PMID: 35670730 PMCID: PMC9216573 DOI: 10.1093/database/baac040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/21/2022] [Accepted: 05/21/2022] [Indexed: 11/13/2022]
Abstract
We introduce SilkBase as an integrated database for transcriptomic and genomic resources of the domesticated silkworm Bombyx mori and related species. SilkBase is the oldest B. mori database that was originally established as the expressed sequence tag database since 1999. Here, we upgraded the database by including the datasets of the newly assembled B. mori complete genome sequence, predicted gene models, bacterial artificial chromosome (BAC)-end and fosmid-end sequences, complementary DNA (cDNA) reads from 69 libraries, RNA-seq data from 10 libraries, PIWI-interacting RNAs (piRNAs) from 13 libraries, ChIP-seq data of 9 histone modifications and HP1 proteins and transcriptome and/or genome data of four B. mori-related species, i.e. Bombyx mandarina, Trilocha varians, Ernolatia moorei and Samia ricini. Our new integrated genome browser easily provides a snapshot of tissue- and stage-specific gene expression, alternative splicing, production of piRNAs and histone modifications at the gene locus of interest. Moreover, SilkBase is useful for performing comparative studies among five closely related lepidopteran insects. Database URL: https://silkbase.ab.a.u-tokyo.ac.jp
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Affiliation(s)
- Munetaka Kawamoto
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.,Infinity Matrix, Shiohama, Koto-ku, Tokyo 135-0043, Japan
| | - Takashi Kiuchi
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Susumu Katsuma
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
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6
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Figon F, Hurbain I, Heiligenstein X, Trépout S, Lanoue A, Medjoubi K, Somogyi A, Delevoye C, Raposo G, Casas J. Catabolism of lysosome-related organelles in color-changing spiders supports intracellular turnover of pigments. Proc Natl Acad Sci U S A 2021; 118:e2103020118. [PMID: 34433668 PMCID: PMC8536372 DOI: 10.1073/pnas.2103020118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pigment organelles of vertebrates belong to the lysosome-related organelle (LRO) family, of which melanin-producing melanosomes are the prototypes. While their anabolism has been extensively unraveled through the study of melanosomes in skin melanocytes, their catabolism remains poorly known. Here, we tap into the unique ability of crab spiders to reversibly change body coloration to examine the catabolism of their pigment organelles. By combining ultrastructural and metal analyses on high-pressure frozen integuments, we first assess whether pigment organelles of crab spiders belong to the LRO family and second, how their catabolism is intracellularly processed. Using scanning transmission electron microscopy, electron tomography, and nanoscale Synchrotron-based scanning X-ray fluorescence, we show that pigment organelles possess ultrastructural and chemical hallmarks of LROs, including intraluminal vesicles and metal deposits, similar to melanosomes. Monitoring ultrastructural changes during bleaching suggests that the catabolism of pigment organelles involves the degradation and removal of their intraluminal content, possibly through lysosomal mechanisms. In contrast to skin melanosomes, anabolism and catabolism of pigments proceed within the same cell without requiring either cell death or secretion/phagocytosis. Our work hence provides support for the hypothesis that the endolysosomal system is fully functionalized for within-cell turnover of pigments, leading to functional maintenance under adverse conditions and phenotypic plasticity. First formulated for eye melanosomes in the context of human vision, the hypothesis of intracellular turnover of pigments gets unprecedented strong support from pigment organelles of spiders.
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Affiliation(s)
- Florent Figon
- Institut de Recherche sur la Biologie de l'Insecte, CNRS UMR 7261, Université de Tours, 37200 Tours, France;
| | - Ilse Hurbain
- Institut Curie, CNRS UMR 144, Structure and Membrane Compartments, Paris Sciences & Lettres (PSL) Research University, 75005 Paris, France
- Institut Curie, CNRS UMR 144, Cell and Tissue Imaging Facility (Plateforme d'Imagerie Cellulaire et Tissulaire, Infrastructures en Biologie, Santé et Agronomie [PICT-IBiSA]), PSL Research University, 75005 Paris, France
| | | | - Sylvain Trépout
- Institut Curie, INSERM U1196, CNRS UMR 9187, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | - Arnaud Lanoue
- Biomolécules et Biotechnologies Végétales, Équipe d'Accueil 2106, Université de Tours, 37200 Tours, France
| | | | | | - Cédric Delevoye
- Institut Curie, CNRS UMR 144, Structure and Membrane Compartments, Paris Sciences & Lettres (PSL) Research University, 75005 Paris, France
- Institut Curie, CNRS UMR 144, Cell and Tissue Imaging Facility (Plateforme d'Imagerie Cellulaire et Tissulaire, Infrastructures en Biologie, Santé et Agronomie [PICT-IBiSA]), PSL Research University, 75005 Paris, France
| | - Graça Raposo
- Institut Curie, CNRS UMR 144, Structure and Membrane Compartments, Paris Sciences & Lettres (PSL) Research University, 75005 Paris, France
- Institut Curie, CNRS UMR 144, Cell and Tissue Imaging Facility (Plateforme d'Imagerie Cellulaire et Tissulaire, Infrastructures en Biologie, Santé et Agronomie [PICT-IBiSA]), PSL Research University, 75005 Paris, France
| | - Jérôme Casas
- Institut de Recherche sur la Biologie de l'Insecte, CNRS UMR 7261, Université de Tours, 37200 Tours, France;
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7
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Bowman SL, Bi-Karchin J, Le L, Marks MS. The road to lysosome-related organelles: Insights from Hermansky-Pudlak syndrome and other rare diseases. Traffic 2020; 20:404-435. [PMID: 30945407 DOI: 10.1111/tra.12646] [Citation(s) in RCA: 120] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 04/02/2019] [Accepted: 04/02/2019] [Indexed: 12/11/2022]
Abstract
Lysosome-related organelles (LROs) comprise a diverse group of cell type-specific, membrane-bound subcellular organelles that derive at least in part from the endolysosomal system but that have unique contents, morphologies and functions to support specific physiological roles. They include: melanosomes that provide pigment to our eyes and skin; alpha and dense granules in platelets, and lytic granules in cytotoxic T cells and natural killer cells, which release effectors to regulate hemostasis and immunity; and distinct classes of lamellar bodies in lung epithelial cells and keratinocytes that support lung plasticity and skin lubrication. The formation, maturation and/or secretion of subsets of LROs are dysfunctional or entirely absent in a number of hereditary syndromic disorders, including in particular the Hermansky-Pudlak syndromes. This review provides a comprehensive overview of LROs in humans and model organisms and presents our current understanding of how the products of genes that are defective in heritable diseases impact their formation, motility and ultimate secretion.
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Affiliation(s)
- Shanna L Bowman
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jing Bi-Karchin
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Linh Le
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Cell and Molecular Biology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Michael S Marks
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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8
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Wang L, Yin Y, Wang K, Cao J, Cheng T, Liu C, Zhang Y, Zhu Y. Bombyx mori monocarboxylate transporter 9 (BmMCT9) is involved in the transport of uric acid in silkworm integument. Genes Cells 2019; 25:33-40. [PMID: 31730247 DOI: 10.1111/gtc.12734] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 11/04/2019] [Accepted: 11/13/2019] [Indexed: 12/17/2022]
Abstract
In Bombyx mori, there are more than 30 mutant strains exhibiting the translucent larval skin resulting from a decrease in the uric acid content in epidermal cell. Of these, the Chinese translucent (oc) mutant presents a moderately translucent larval skin. Previously, we narrowed the region linked to the oc phenotype to approximately 234 kb by positional cloning, and found that BmMCT9 was severely suppressed in the mutant. Here, we analyzed the mutation and potential molecular function of BmMCT9. Sequence analysis showed that a 2,624-bp fragment of BmMCT9 promoter region was replaced by a 22-bp sequence in the mutant. Luciferase reporter gene assay confirmed that BmMCT9 promoter activity in the mutant was significantly lower than that in the wild type. Knockdown of BmMCT9 caused a translucent phenotype in the first-instar silkworm larvae. Immunoblotting analysis showed that BmMCT9 expression was severely reduced in the mutant than in the wild type, and immunofluorescence showed that BmMCT9 existed mainly within the cytoplasm of epidermal cells. Together, our results suggest that reduced levels of BmMCT9 were responsible for the translucent phenotype of oc mutant, and that BmMCT9 might function in intracellular vesicles facing the cytoplasm including urate granules in silkworm integument.
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Affiliation(s)
- Lingyan Wang
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Chongqing, China.,Biological Science Research Center, Southwest University, Chongqing, China
| | - Yaru Yin
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Chongqing, China
| | - Kun Wang
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Chongqing, China
| | - Jun Cao
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Chongqing, China
| | - Tingcai Cheng
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Chongqing, China
| | - Chun Liu
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Chongqing, China
| | - Yan Zhang
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Chongqing, China.,Biological Science Research Center, Southwest University, Chongqing, China
| | - Yong Zhu
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Chongqing, China
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9
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Kawamoto M, Jouraku A, Toyoda A, Yokoi K, Minakuchi Y, Katsuma S, Fujiyama A, Kiuchi T, Yamamoto K, Shimada T. High-quality genome assembly of the silkworm, Bombyx mori. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 107:53-62. [PMID: 30802494 DOI: 10.1016/j.ibmb.2019.02.002] [Citation(s) in RCA: 151] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 02/13/2019] [Accepted: 02/18/2019] [Indexed: 05/21/2023]
Abstract
In 2008, the genome assembly and gene models for the domestic silkworm, Bombyx mori, were published by a Japanese and Chinese collaboration group. However, the genome assembly contains a non-negligible number of misassembled and gap regions due to the presence of many repetitive sequences within the silkworm genome. The erroneous genome assembly occasionally causes incorrect gene prediction. Here we performed hybrid assembly based on 140 × deep sequencing of long (PacBio) and short (Illumina) reads. The remaining gaps in the initial genome assembly were closed using BAC and Fosmid sequences, giving a new total length of 460.3 Mb, with 30 gap regions and an N50 comprising 16.8 Mb in scaffolds and 12.2 Mb in contigs. More RNA-seq and piRNA-seq reads were mapped on the new genome assembly compared with the previous version, indicating that the new genome assembly covers more transcribed regions, including repetitive elements. We performed gene prediction based on the new genome assembly using available mRNA and protein sequence data. The number of gene models was 16,880 with an N50 of 2154 bp. The new gene models reflected more accurate coding sequences and gene sets than old ones. The proportion of repetitive elements was also reestimated using the new genome assembly, and was calculated to be 46.8% in the silkworm genome. The new genome assembly and gene models are provided in SilkBase (http://silkbase.ab.a.u-tokyo.ac.jp).
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Affiliation(s)
- Munetaka Kawamoto
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Akiya Jouraku
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Atsushi Toyoda
- Comparative Genomics Laboratory, Center for Information Biology, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan; Advanced Genomics Center, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan
| | - Kakeru Yokoi
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Yohei Minakuchi
- Comparative Genomics Laboratory, Center for Information Biology, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan
| | - Susumu Katsuma
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Asao Fujiyama
- Comparative Genomics Laboratory, Center for Information Biology, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan; Advanced Genomics Center, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan
| | - Takashi Kiuchi
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
| | - Kimiko Yamamoto
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan.
| | - Toru Shimada
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
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10
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Figon F, Casas J. Ommochromes in invertebrates: biochemistry and cell biology. Biol Rev Camb Philos Soc 2019; 94:156-183. [PMID: 29989284 DOI: 10.1111/brv.12441] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 06/09/2018] [Accepted: 06/12/2018] [Indexed: 01/24/2023]
Abstract
Ommochromes are widely occurring coloured molecules of invertebrates, arising from tryptophan catabolism through the so-called Tryptophan → Ommochrome pathway. They are mainly known to mediate compound eye vision, as well as reversible and irreversible colour patterning. Ommochromes might also be involved in cell homeostasis by detoxifying free tryptophan and buffering oxidative stress. These biological functions are directly linked to their unique chromophore, the phenoxazine/phenothiazine system. The most recent reviews on ommochrome biochemistry were published more than 30 years ago, since when new results on the enzymes of the ommochrome pathway, on ommochrome photochemistry as well as on their antiradical capacities have been obtained. Ommochromasomes are the organelles where ommochromes are synthesised and stored. Hence, they play an important role in mediating ommochrome functions. Ommochromasomes are part of the lysosome-related organelles (LROs) family, which includes other pigmented organelles such as vertebrate melanosomes. Ommochromasomes are unique because they are the only LRO for which a recycling process during reversible colour change has been described. Herein, we provide an update on ommochrome biochemistry, photoreactivity and antiradical capacities to explain their diversity and behaviour both in vivo and in vitro. We also highlight new biochemical techniques, such as quantum chemistry, metabolomics and crystallography, which could lead to major advances in their chemical and functional characterisation. We then focus on ommochromasome structure and formation by drawing parallels with the well-characterised melanosomes of vertebrates. The biochemical, genetic, cellular and microscopic tools that have been applied to melanosomes should provide important information on the ommochromasome life cycle. We propose LRO-based models for ommochromasome biogenesis and recycling that could be tested in the future. Using the context of insect compound eyes, we finally emphasise the importance of an integrated approach in understanding the biological functions of ommochromes.
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Affiliation(s)
- Florent Figon
- Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 7261, Université de Tours, 37200 Tours, France
| | - Jérôme Casas
- Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 7261, Université de Tours, 37200 Tours, France
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Fujii T, Banno Y. Identification of a novel function of the silkworm integument in nitrogen metabolism: Uric acid is synthesized within the epidermal cells in B. mori. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 105:43-50. [PMID: 30610924 DOI: 10.1016/j.ibmb.2018.12.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 12/28/2018] [Accepted: 12/28/2018] [Indexed: 06/09/2023]
Abstract
During nitrogen metabolism, animals convert toxic ammonia to less toxic forms. Uric acid (UA) is an end product of this process in terrestrial insects. In lepidopteran larvae, a large amount of UA is stored in the integument via a phenomenon known as storage excretion. Physiologically, integumental UA plays crucial roles as a barrier against sunlight and as a white pigment for larval pigmentation patterns. Conventionally, UA is thought to be synthesized in the fat body, the insect equivalent of the liver of vertebrates, and to be transported to the epidermis via the hemolymph. Here, we reconsidered the conventional theory by a mosaic analysis targeting genes governing UA synthesis, using CRISPR/Cas9 mutagenesis and a traditional genetic method in Bombyx mori. Notably, we observed mosaic larvae in which the integument comprised both UA-containing white and UA-lacking translucent areas, indicating that UA synthesis in the epidermis is indispensable to the accumulation of a large amount of highly insoluble UA in the epidermis. Our results thus provide a genetic basis for storage excretion wherein lepidopteran insects use nitrogenous waste to adapt to their environment.
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Affiliation(s)
- Tsuguru Fujii
- Laboratory of Silkworm Genetic Resources, Institute of Genetic Resources, Graduate School of io Resources and Bioenvironmental Science, Kyushu University, Fukuoka, 819-0395, Japan.
| | - Yutaka Banno
- Laboratory of Silkworm Genetic Resources, Institute of Genetic Resources, Graduate School of io Resources and Bioenvironmental Science, Kyushu University, Fukuoka, 819-0395, Japan
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Wang L, Dong Z, Wang J, Yin Y, Liu H, Hu W, Peng Z, Liu C, Li M, Banno Y, Shimada T, Xia Q, Zhao P. Proteomic Analysis of Larval Integument in a Dominant Obese Translucent (Obs) Silkworm Mutant. JOURNAL OF INSECT SCIENCE (ONLINE) 2018; 18:5168485. [PMID: 30412263 PMCID: PMC6225826 DOI: 10.1093/jisesa/iey098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Indexed: 06/08/2023]
Abstract
The dominant obese translucent (Obs) mutant of the silkworm (Bombyx mori) results in a short and stout larval body, translucent phenotype, and abnormal pigmentation in the integument. The Obs mutant also displays deficiency in ecdysis and metamorphosis. In the present study, to gain an understanding of multiple Obs phenotypes, we investigated the phenotypes of Obs and performed a comparative analysis of the larval integument proteomes of Obs and normal silkworms. The phenotypic analysis revealed that the Obs larvae were indeed short and fat, and that chitin and uric acid content were lower but melanin content was higher in the Obs mutant. Proteomic analysis revealed that 244 proteins were significantly differentially expressed between Obs and normal silkworms, some of which were involved in uric acid metabolism and melanin pigmentation. Twenty-six proteins were annotated as cuticular proteins, including RR motif-rich cuticular proteins (CPR), glycine-rich cuticular protein (CPG), hypothetical cuticular protein (CPH), cuticular protein analogous to peritrophins (CPAPs), and the chitin_bind_3 motif proteins, and accounted for over 84% of the abundance of the total significantly differentially expressed proteins. Moreover, 22 of the 26 cuticular proteins were downregulated in the Obs mutant. Comparative proteomic analysis suggested that the multiple phenotypes of the Obs mutant might be related to changes in the expression of proteins that participate in cuticular formation, uric acid metabolism, and melanin pigmentation. These results could lay a basis for further identification of the gene responsible for the Obs mutant. The data have been deposited to ProteomeXchange with identifier PXD010998.
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Affiliation(s)
- Lingyan Wang
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Tiansheng Road, Beibei, Chongqing, China
| | - Zhaoming Dong
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Tiansheng Road, Beibei, Chongqing, China
| | - Juan Wang
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Tiansheng Road, Beibei, Chongqing, China
| | - Yaru Yin
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Tiansheng Road, Beibei, Chongqing, China
| | - Huawei Liu
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Tiansheng Road, Beibei, Chongqing, China
| | - Wenbo Hu
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Tiansheng Road, Beibei, Chongqing, China
| | - Zhangchuan Peng
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Tiansheng Road, Beibei, Chongqing, China
| | - Chun Liu
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Tiansheng Road, Beibei, Chongqing, China
| | - Muwang Li
- Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu, China
| | - Yutaka Banno
- Institute of Genetic Resources, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Higashi-ku, Fukuoka, Japan
| | - Toru Shimada
- Department of Agricultural and Environmental Biology, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Qingyou Xia
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Tiansheng Road, Beibei, Chongqing, China
| | - Ping Zhao
- State Key Laboratory of Silkworm Genome Biology, College of Biotechnology, Southwest University, Tiansheng Road, Beibei, Chongqing, China
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Zhang H, Kiuchi T, Hirayama C, Banno Y, Katsuma S, Shimada T. A reexamination on the deficiency of riboflavin accumulation in Malpighian tubules in larval translucent mutants of the silkworm, Bombyx mori. Genetica 2018; 146:425-431. [PMID: 30094710 DOI: 10.1007/s10709-018-0034-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Accepted: 08/03/2018] [Indexed: 12/25/2022]
Abstract
A variety of insects accumulate high contents of riboflavin (vitamin B2) in their Malpighian tubules (MTs). Although this process is known to be genetically controlled, the mechanism is not known. In the 1940s and the 1950s, several studies showed that riboflavin contents were low in the MTs of some Bombyx mori (silkworm) mutants with translucent larval skin mutations (e.g., w-3, od, oa, and otm) and that genes responsible for these translucent mutations also affected riboflavin accumulation in the MTs. Since the 2000s, it has been shown that the w-3 gene encodes an ABC transporter, whereas genes responsible for od, oa, and otm mutations encode for the biogenesis of lysosome-related organelles. These findings suggest that some genes of ABC transporters and biogenesis of lysosome-related organelles may control the accumulation of riboflavin in MTs. Therefore, we reexamined the effects that translucent mutations have on the accumulation of riboflavin in MTs by using the translucent and wild-type segregants in mutant strains to measure the specific effect that each gene has on riboflavin accumulation (independent of genomic background). We used nine translucent mutations (w-3oe, oa, od, otm, Obs, oy, or, oh, and obt) even though the genes responsible for some of these mutations (Obs, oy, or, oh, and obt) have not yet been isolated. Through observation of larval MTs and measurements of riboflavin content using high-performance liquid chromatography, we found that the oa, od, otm, and or mutations were responsible for low contents of riboflavin in MTs, whereas the Obs and oy mutations did not affect riboflavin accumulation. This indicates that the molecular mechanism for riboflavin accumulation is similar but somewhat different than the mechanism responsible for uric acid accumulation in epidermal cells. We found that the genes responsible for oa, od, and otm mutations were consistent with those already established for uric acid accumulation in larval epidermis. This suggests that these three genes control riboflavin accumulation in MTs through a mechanism similar to that of uric acid accumulation, although we do not yet know why the or mutation also controls riboflavin accumulation.
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Affiliation(s)
- Haokun Zhang
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
- School of Life Science, Fudan University, 2005 Songhu Road, Shanghai, 200438, China
| | - Takashi Kiuchi
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Chikara Hirayama
- National Agriculture and Food Research Organization, 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Yutaka Banno
- Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Hakozaki, Higashi-Ku, Fukuoka, 812-8581, Japan
| | - Susumu Katsuma
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Toru Shimada
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
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Fujii T, Yamamoto K, Banno Y. Translucent larval integument and flaccid paralysis caused by genome editing in a gene governing molybdenum cofactor biosynthesis in Bombyx mori. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2018; 99:11-16. [PMID: 29803701 DOI: 10.1016/j.ibmb.2018.04.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 04/28/2018] [Accepted: 04/28/2018] [Indexed: 06/08/2023]
Abstract
Translucency of the larval integument in Bombyx mori is caused by a lack of uric acid in the epidermis. Hime'nichi translucent (ohi) is a unique mutation causing intermediate translucency of the larval integument and male-specific flaccid paralysis. To determine the gene associated with the ohi mutation, the ohi locus was mapped to a 400-kb region containing 29 predicted genes. Among the genes in this region, we focused on Bombyx homolog of mammalian Gephyrin (BmGphn), which regulates molybdenum cofactor (MoCo) biosynthesis, because MoCo is indispensable for the activity of xanthine dehydrogenase (XDH), a key enzyme in uric acid biosynthesis. The translucent integument of ohi larvae turned opaque after injection of bovine xanthine oxidase, which is a mammalian equivalent to XDH, indicating that XDH activity is defective in ohi larvae. RT-PCR and sequencing analysis showed that (i) in ohi larvae, expression of the BmGphn gene was repressed in the fat body where uric acid is synthesized, and (ii) there was no amino acid substitution in the ohi mutant allele. Finally, we obtained BmGphn knockout alleles (hereafter denoted as BmGphnΔ) by using CRISPR/Cas9. The resulting ohi/BmGphnΔ larvae had translucent integuments, demonstrating that BmGphn is the gene responsible for the ohi phenotype. Our results show that repressed expression of BmGphn is a causative factor for the defective MoCo biosynthesis and XDH activity observed in ohi larvae. Interestingly, all male BmGphnΔ homozygotes died before pupation and showed a flaccid paralysis phenotype. The genetic and physiological mechanisms underlying this flaccid paralysis phenotype are also discussed.
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Affiliation(s)
- Tsuguru Fujii
- Laboratory of Silkworm Genetic Resources, Institute of Genetic Resources, Graduate School of Bio Resources and Bioenvironmental Science, Kyushu University, Fukuoka, 812-8581, Japan
| | - Kazunori Yamamoto
- Laboratory of Silkworm Genetic Resources, Institute of Genetic Resources, Graduate School of Bio Resources and Bioenvironmental Science, Kyushu University, Fukuoka, 812-8581, Japan
| | - Yutaka Banno
- Laboratory of Silkworm Genetic Resources, Institute of Genetic Resources, Graduate School of Bio Resources and Bioenvironmental Science, Kyushu University, Fukuoka, 812-8581, Japan.
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Zhang H, Kiuchi T, Hirayama C, Katsuma S, Shimada T. Bombyx ortholog of the Drosophila eye color gene brown controls riboflavin transport in Malpighian tubules. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2018; 92:65-72. [PMID: 29191464 DOI: 10.1016/j.ibmb.2017.11.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 11/24/2017] [Accepted: 11/25/2017] [Indexed: 06/07/2023]
Abstract
The Drosophila eye color gene brown is known to control the transport of pteridine precursors in adult eyes. The Brown protein belongs to the ATP-binding cassette (ABC) transporter G family, which includes proteins encoded by the genes brown, scarlet, and white. These genes are responsible for pigmentation in Drosophila and the domestic silkworm Bombyx mori. Although orthologs of brown are conserved among insects, the function of this gene is only known in Drosophila. Here, we elucidated the function of the B. mori ortholog Bm-brown. We examined the spatial and temporal expression profiles of Bm-brown and found that this gene was specifically and continuously expressed in larval Malpighian tubules (MTs), indicating this gene has a special function in MTs. We then successfully obtained a Bm-brown knockout (KO) strain based on a wild-type (WT) strain using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated nuclease 9 (Cas9) system. We found that larval MTs of the KO strain were white, whereas those of WT were yellow. It is known that larval yellow MTs of WT are due to the accumulation of riboflavin. Therefore, we compared the riboflavin contents of MTs of KO and WT strains, and found that the riboflavin level in the KO strain was 20 fold less than that in WT during the 5th instar period. MTs are known to exhibit a similar milky color in w-3 mutant larvae due to a deficiency of riboflavin accumulation. The responsible gene for w-3 mutant is the Bmwh3 gene, which is orthologous to Drosophila white. Thus, we speculate that Bm-brown is heterodimerized with Bmwh3, similar to Brown/White in Drosophila, and acts as a riboflavin transporter in silkworm MTs.
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Affiliation(s)
- Haokun Zhang
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takashi Kiuchi
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Chikara Hirayama
- National Agriculture and Food Research Organization, 1-2 Owashi, Tsukuba City, Ibaraki 305-8634, Japan
| | - Susumu Katsuma
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Toru Shimada
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
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