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Bai Y, Lv YN, Zeng M, Yan ZY, Huang DY, Wen JZ, Lu HN, Zhang PY, Wang YF, Ban N, Yuan DW, Li S, Luan YX. E93 is indispensable for reproduction in ametabolous and hemimetabolous insects. Development 2024; 151:dev202518. [PMID: 38646855 DOI: 10.1242/dev.202518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 04/15/2024] [Indexed: 04/23/2024]
Abstract
Ecdysone-induced protein 93 (E93), known as the 'adult-specifier' transcription factor in insects, triggers metamorphosis in both hemimetabolous and holometabolous insects. Although E93 is conserved in ametabolous insects, its spatiotemporal expression and physiological function remain poorly understood. In this study, we first discover that, in the ametabolous firebrat Thermobia domestica, the previtellogenic ovary exhibits cyclically high E93 expression, and E93 mRNA is broadly distributed in previtellogenic ovarioles. E93 homozygous mutant females of T. domestica exhibit severe fecundity deficiency due to impaired previtellogenic development of the ovarian follicles, likely because E93 induces the expression of genes involved in ECM (extracellular matrix)-receptor interactions during previtellogenesis. Moreover, we reveal that in the hemimetabolous cockroach Blattella germanica, E93 similarly promotes previtellogenic ovarian development. In addition, E93 is also essential for vitellogenesis that is necessary to guarantee ovarian maturation and promotes the vitellogenesis-previtellogenesis switch in the fat body of adult female cockroaches. Our findings deepen the understanding of the roles of E93 in controlling reproduction in insects, and of E93 expression and functional evolution, which are proposed to have made crucial contributions to the origin of insect metamorphosis.
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Affiliation(s)
- Yu Bai
- Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510000, China
- Guangmeiyuan R&D Center, Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, South China Normal University, Meizhou 514000, China
| | - Ya-Nan Lv
- Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510000, China
| | - Mei Zeng
- Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510000, China
| | - Zi-Yu Yan
- Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510000, China
| | - Dan-Yan Huang
- Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510000, China
| | - Jia-Zhen Wen
- Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510000, China
| | - Hu-Na Lu
- Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510000, China
| | - Pei-Yan Zhang
- Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510000, China
| | - Yi-Fan Wang
- Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510000, China
| | - Ning Ban
- Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510000, China
| | - Dong-Wei Yuan
- Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510000, China
| | - Sheng Li
- Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510000, China
- Guangmeiyuan R&D Center, Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, South China Normal University, Meizhou 514000, China
| | - Yun-Xia Luan
- Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510000, China
- Guangmeiyuan R&D Center, Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, South China Normal University, Meizhou 514000, China
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2
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Truman JW, Riddiford LM, Konopova B, Nouzova M, Noriega FG, Herko M. The embryonic role of juvenile hormone in the firebrat, Thermobia domestica, reveals its function before its involvement in metamorphosis. eLife 2024; 12:RP92643. [PMID: 38568859 PMCID: PMC10994664 DOI: 10.7554/elife.92643] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2024] Open
Abstract
To gain insights into how juvenile hormone (JH) came to regulate insect metamorphosis, we studied its function in the ametabolous firebrat, Thermobia domestica. Highest levels of JH occur during late embryogenesis, with only low levels thereafter. Loss-of-function and gain-of-function experiments show that JH acts on embryonic tissues to suppress morphogenesis and cell determination and to promote their terminal differentiation. Similar embryonic actions of JH on hemimetabolous insects with short germ band embryos indicate that JH's embryonic role preceded its derived function as the postembryonic regulator of metamorphosis. The postembryonic expansion of JH function likely followed the evolution of flight. Archaic flying insects were considered to lack metamorphosis because tiny, movable wings were evident on the thoraces of young juveniles and their positive allometric growth eventually allowed them to support flight in late juveniles. Like in Thermobia, we assume that these juveniles lacked JH. However, a postembryonic reappearance of JH during wing morphogenesis in the young juvenile likely redirected wing development to make a wing pad rather than a wing. Maintenance of JH then allowed wing pad growth and its disappearance in the mature juvenile then allowed wing differentiation. Subsequent modification of JH action for hemi- and holometabolous lifestyles are discussed.
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Affiliation(s)
- James W Truman
- Friday Harbor Laboratories, University of WashingtonFriday HarborUnited States
- Department of Biology, University of WashingtonSeattleUnited States
| | - Lynn M Riddiford
- Friday Harbor Laboratories, University of WashingtonFriday HarborUnited States
- Department of Biology, University of WashingtonSeattleUnited States
| | - Barbora Konopova
- Department of Zoology, Faculty of Science, University of South BohemiaCeske BudejoviceCzech Republic
- Institute of Entomology, Biology Centre of the Czech Academy of SciencesCeske BudejoviceCzech Republic
| | - Marcela Nouzova
- Institute of Parasitology, Biology Centre of the Czech Academy of SciencesCeske BudejoviceCzech Republic
| | - Fernando G Noriega
- Department of Biological Sciences and BSI, Florida International UniversityMiamiUnited States
- Department of Parasitology, Faculty of Science, University of South BohemiaCeské BudejoviceCzech Republic
| | - Michelle Herko
- Friday Harbor Laboratories, University of WashingtonFriday HarborUnited States
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Gallois M, Menoret D, Marques-Prieto S, Montigny A, Valenti P, Moussian B, Plaza S, Payre F, Chanut-Delalande H. Pri peptides temporally coordinate transcriptional programs during epidermal differentiation. SCIENCE ADVANCES 2024; 10:eadg8816. [PMID: 38335295 PMCID: PMC10857433 DOI: 10.1126/sciadv.adg8816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 01/09/2024] [Indexed: 02/12/2024]
Abstract
To achieve a highly differentiated state, cells undergo multiple transcriptional processes whose coordination and timing are not well understood. In Drosophila embryonic epidermal cells, polished-rice (Pri) smORF peptides act as temporal mediators of ecdysone to activate a transcriptional program leading to cell shape remodeling. Here, we show that the ecdysone/Pri axis concomitantly represses the transcription of a large subset of cuticle genes to ensure proper differentiation of the insect exoskeleton. The repression relies on the transcription factor Ken and persists for several days throughout early larval stages, during which a soft cuticle allows larval crawling. The onset of these cuticle genes normally awaits the end of larval stages when the rigid pupal case assembles, and their premature expression triggers abnormal sclerotization of the larval cuticle. These results uncovered a temporal switch to set up distinct structures of cuticles adapted to the animal lifestyle and which might be involved in the evolutionary history of insects.
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Affiliation(s)
- Maylis Gallois
- Molecular Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, Toulouse, France
| | - Delphine Menoret
- Molecular Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, Toulouse, France
| | - Simon Marques-Prieto
- Molecular Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, Toulouse, France
| | - Audrey Montigny
- Molecular Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, Toulouse, France
| | - Philippe Valenti
- Molecular Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, Toulouse, France
| | - Bernard Moussian
- Université Côte d'Azur, INRAE, CNRS, Institut Sophia Agrobiotech, Sophia Antipolis, France
| | - Serge Plaza
- Laboratoire de Recherche en Sciences Végétales, CNRS/UPS/INPT, Auzeville-Tolosane, France
| | - François Payre
- Molecular Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, Toulouse, France
| | - Hélène Chanut-Delalande
- Molecular Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, Toulouse, France
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4
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Truman JW, Riddiford LM, Konopová B, Nouzova M, Noriega FG, Herko M. The embryonic role of juvenile hormone in the firebrat, Thermobia domestica, reveals its function before its involvement in metamorphosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.06.561279. [PMID: 37873170 PMCID: PMC10592639 DOI: 10.1101/2023.10.06.561279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
To gain insights into how juvenile hormone (JH) came to regulate insect metamorphosis, we studied its function in the ametabolous firebrat, Thermobia domestica. Highest levels of JH occur during late embryogenesis, with only low levels thereafter. Loss-of-function and gain-of-function experiments show that JH acts on embryonic tissues to suppress morphogenesis and cell determination and to promote their terminal differentiation. Similar embryonic actions of JH on hemimetabolous insects with short germ band embryos indicate that JH's embryonic role preceded its derived function as the postembryonic regulator of metamorphosis. The postembryonic expansion of JH function likely followed the evolution of flight. Archaic flying insects were considered to lack metamorphosis because tiny, movable wings were evident on the thoraces of young juveniles and their positive allometric growth eventually allowed them to support flight in late juveniles. Like in Thermobia, we assume that these juveniles lacked JH. However, a postembryonic reappearance of JH during wing morphogenesis in the young juvenile likely redirected wing development to make a wing pad rather than a wing. Maintenance of JH then allowed wing pad growth and its disappearance in the mature juvenile then allowed wing differentiation. Subsequent modification of JH action for hemi- and holometabolous lifestyles are discussed.
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Affiliation(s)
- James W. Truman
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA, USA
- Department of Biology, University of Washington, Seattle, WA USA
| | - Lynn M. Riddiford
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA, USA
- Department of Biology, University of Washington, Seattle, WA USA
| | - Barbora Konopová
- Department of Zoology, Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
- Institute of Entomology, Biology Centre of the Czech Academy of Sciences, Ceske Budejovice, Czech Republic
| | - Marcela Nouzova
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Ceske Budejovice, Czech Republic
| | - Fernando G. Noriega
- Department of Biological Sciences and BSI, Florida International University, FL ,USA
- Department of Parasitology, Faculty of Science, University of South Bohemia, Ceské Budejovice, Czech Republic
| | - Michelle Herko
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA, USA
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5
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Belles X. Investigating the origin of insect metamorphosis. eLife 2023; 12:e94410. [PMID: 38126357 PMCID: PMC10735215 DOI: 10.7554/elife.94410] [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] [Indexed: 12/23/2023] Open
Abstract
Experiments exploring the role of juvenile hormone during the life cycle of firebrat insects provide clues about the evolution of metamorphosis.
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Affiliation(s)
- Xavier Belles
- Evolution of Insect Metamorphosis Lab, Institute of Evolutionary Biology, CSIC-Pompeu Fabra UniversityBarcelonaSpain
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Domínguez E, van de Kamp T, Mikó I, Cuezzo MG, Staniczek AH. The function of wing bullae in mayflies (Insecta: Ephemeroptera) reveals new insights into the early evolution of Pterygota. BMC Biol 2023; 21:268. [PMID: 37996928 PMCID: PMC10666447 DOI: 10.1186/s12915-023-01750-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 10/30/2023] [Indexed: 11/25/2023] Open
Abstract
BACKGROUND Mayflies are basal winged insects of crucial importance for the understanding of the early evolution of Pterygota. Unlike all other insects, they have two successive winged stages, the subimago and the imago. Their forewings feature so-called bullae, which are desclerotized spots in the anterior main veins. Up to now, they have been considered to play a major role in wing bending during flight. RESULTS We investigated bullae by multiple methods to reveal their structure and arrangement and to gain new information on the evolution of insect flight. Bullae are mostly present in the anterior negative wing veins, disrupting the otherwise rigid veins. High-speed videography reveals that mayfly wings do not bend during flight. Likewise, different arrangements of bullae in different species do not correlate with different modes of flying. Observations on the moulting of subimagines unravel that they are essential for wing bending during the extraction of the imaginal wing from the subimaginal cuticle. Bullae define predetermined bending lines, which, together with a highly flexible wing membrane enriched with resilin, permit wing bending during subimaginal moulting. Bullae are only absent in those species that remain in the subimaginal stage or that use modified modes of moulting. Bullae are also visible in fossil mayflies and can be traced back to stemgroup mayflies of the Early Permian, the 270 million years old Protereismatidae, which most probably had bullae in both fore- and hind wings. CONCLUSIONS Bullae in mayfly wings do not play a role in flight as previously thought, but are crucial for wing bending during subimaginal moulting. Thus, the presence of bullae is a reliable morphological marker for a subimaginal life stage, confirming the existence of the subimago already in Permian Protereismatidae. A thorough search for bullae in fossils of other pterygote lineages may reveal wheather they also had subimagines and at what point in evolution this life stage was lost. In mayflies, however, the subimago may have been retained due to selective advantages in connection with the transition from aquatic to terrestrial life or due to morphological requirements for a specialized mating flight.
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Affiliation(s)
- Eduardo Domínguez
- Instituto de Biodiversidad Neotropical (IBN), CONICET- Facultad de Ciencias Naturales, Universidad Nacional de Tucumán (U.N.T.), Miguel Lillo 205, 4000, Tucumán, Argentina
| | - Thomas van de Kamp
- Institute for Photon Science and Synchrotron Radiation (IPS), Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany
- Laboratory for Applications of Synchrotron Radiation (LAS), Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - István Mikó
- Department of Biological Sciences, University of New Hampshire, Durham, NH, 03824, USA
| | - M Gabriela Cuezzo
- Instituto de Biodiversidad Neotropical (IBN), CONICET- Facultad de Ciencias Naturales, Universidad Nacional de Tucumán (U.N.T.), Miguel Lillo 205, 4000, Tucumán, Argentina
| | - Arnold H Staniczek
- Department of Entomology, State Museum of Natural History Stuttgart, Rosenstein 1, 70191, Stuttgart, Germany.
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Thum AS, Gerber B. The making of a maggot brain. eLife 2023; 12:86696. [PMID: 36867155 PMCID: PMC9984190 DOI: 10.7554/elife.86696] [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] [Indexed: 03/04/2023] Open
Abstract
The way neurons in the brain rewire in larvae as they turn to adult fruit flies sheds light on how complete metamorphosis was 'invented' over the course of evolution.
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Affiliation(s)
- Andreas S Thum
- Institute of Biology, University of LeipzigLeipzigGermany
| | - Bertram Gerber
- Department Genetics of Learning and Memory, Leibniz Institute for NeurobiologyMagdeburgGermany
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Prokop J, Nel A, Engel MS. Diversity, Form, and Postembryonic Development of Paleozoic Insects. ANNUAL REVIEW OF ENTOMOLOGY 2023; 68:401-429. [PMID: 36689304 DOI: 10.1146/annurev-ento-120220-022637] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
While Mesozoic, Paleogene, and Neogene insect faunas greatly resemble the modern one, the Paleozoic fauna provides unique insights into key innovations in insect evolution, such as the origin of wings and modifications of postembryonic development including holometaboly. Deep-divergence estimates suggest that the majority of contemporary insect orders originated in the Late Paleozoic, but these estimates reflect divergences between stem groups of each lineage rather than the later appearance of the crown groups. The fossil record shows the initial radiations of the extant hyperdiverse clades during the Early Permian, as well as the specialized fauna present before the End Permian mass extinction. This review summarizes the recent discoveries related to the documented diversity of Paleozoic hexapods, as well as current knowledge about what has actually been verified from fossil evidence as it relates to postembryonic development and the morphology of different body parts.
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Affiliation(s)
- Jakub Prokop
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic;
| | - André Nel
- Institut de Systématique, Évolution, Biodiversité (ISYEB), Muséum national d'Histoire naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, Paris, France;
| | - Michael S Engel
- Division of Entomology, University of Kansas Natural History Museum, Lawrence, Kansas, USA;
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, USA
- Division of Invertebrate Zoology, American Museum of Natural History, New York, New York, USA
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He Q, Zhang Y. Kr-h1, a Cornerstone Gene in Insect Life History. Front Physiol 2022; 13:905441. [PMID: 35574485 PMCID: PMC9092015 DOI: 10.3389/fphys.2022.905441] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Accepted: 04/13/2022] [Indexed: 11/13/2022] Open
Abstract
Insect life cycle is coordinated by hormones and their downstream effectors. Krüppel homolog1 (Kr-h1) is one of the crucial effectors which mediates the actions of the two critical hormones of insects, the juvenile hormone (JH) and 20-hydroxyecdysone (20E). It is a transcription factor with a DNA-binding motif of eight C2H2 zinc fingers which is found to be conserved among insect orders. The expression of Kr-h1 is fluctuant during insect development with high abundance in juvenile instars and lower levels in the final instar and pupal stage, and reappearance in adults, which is governed by the coordination of JH, 20E, and miRNAs. The dynamic expression pattern of Kr-h1 is closely linked to its function in the entire life of insects. Over the past several years, accumulating studies have advanced our understanding of the role of Kr-h1 during insect development. It acts as a universal antimetamorphic factor in both hemimetabolous and holometabolous species by directly inhibiting the transcription of 20E signaling genes Broad-Complex (Br-C) and Ecdysone induced protein 93F (E93), and steroidogenic enzyme genes involved in ecdysone biosynthesis. Meanwhile, it promotes vitellogenesis and ovarian development in the majority of studied insects. In addition, Kr-h1 regulates insect behavioral plasticity and caste identity, neuronal morphogenesis, maturation of sexual behavior, as well as embryogenesis and metabolic homeostasis. Hence, Kr-h1 acts as a cornerstone regulator in insect life.
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Affiliation(s)
- Qianyu He
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, China
| | - Yuanxi Zhang
- Daqing Municipal Ecology and Environment Bureau, Daqing, China
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Oguchi K, Koshikawa S, Miura T. Hormone-related genes heterochronically and modularly regulate neotenic differentiation in termites. Dev Biol 2022; 485:70-79. [DOI: 10.1016/j.ydbio.2022.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 02/22/2022] [Accepted: 02/26/2022] [Indexed: 11/26/2022]
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Lam G, Nam HJ, Velentzas PD, Baehrecke EH, Thummel CS. Drosophila E93 promotes adult development and suppresses larval responses to ecdysone during metamorphosis. Dev Biol 2022; 481:104-115. [PMID: 34648816 PMCID: PMC8665130 DOI: 10.1016/j.ydbio.2021.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/30/2021] [Accepted: 10/05/2021] [Indexed: 01/03/2023]
Abstract
Pulses of the steroid hormone ecdysone act through transcriptional cascades to direct the major developmental transitions during the Drosophila life cycle. These include the prepupal ecdysone pulse, which occurs 10 hours after pupariation and triggers the onset of adult morphogenesis and larval tissue destruction. E93 encodes a transcription factor that is specifically induced by the prepupal pulse of ecdysone, supporting a model proposed by earlier work that it specifies the onset of adult development. Although a number of studies have addressed these functions for E93, little is known about its roles in the salivary gland where the E93 locus was originally identified. Here we show that E93 is required for development through late pupal stages, with mutants displaying defects in adult differentiation and no detectable effect on the destruction of larval salivary glands. RNA-seq analysis demonstrates that E93 regulates genes involved in development and morphogenesis in the salivary glands, but has little effect on cell death gene expression. We also show that E93 is required to direct the proper timing of ecdysone-regulated gene expression in salivary glands, and that it suppresses earlier transcriptional programs that occur during larval and prepupal stages. These studies support the model that the stage-specific induction of E93 in late prepupae provides a critical signal that defines the end of larval development and the onset of adult differentiation.
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Affiliation(s)
- Geanette Lam
- Department of Human Genetics, University of Utah School of Medicine, 15 N 2030 E Rm 5100, Salt Lake City, UT 84112 USA
| | - Hyuck-Jin Nam
- Department of Human Genetics, University of Utah School of Medicine, 15 N 2030 E Rm 5100, Salt Lake City, UT 84112 USA
| | - Panagiotis D. Velentzas
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605 USA
| | - Eric H. Baehrecke
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605 USA
| | - Carl S. Thummel
- Department of Human Genetics, University of Utah School of Medicine, 15 N 2030 E Rm 5100, Salt Lake City, UT 84112 USA,Corresponding author. (C.S. Thummel)
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12
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Wu Z, Yang L, Li H, Zhou S. Krüppel-homolog 1 exerts anti-metamorphic and vitellogenic functions in insects via phosphorylation-mediated recruitment of specific cofactors. BMC Biol 2021; 19:222. [PMID: 34625063 PMCID: PMC8499471 DOI: 10.1186/s12915-021-01157-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 09/24/2021] [Indexed: 11/23/2022] Open
Abstract
Background The zinc-finger transcription factor Krüppel-homolog 1 (Kr-h1) exerts a dual regulatory role during insect development by preventing precocious larval/nymphal metamorphosis and in stimulating aspects of adult reproduction such as vitellogenesis. However, how Kr-h1 functions both as a transcriptional repressor in juvenile metamorphosis and an activator in adult reproduction remains elusive. Here, we use the insect Locusta migratoria to dissect the molecular mechanism by which Kr-h1 functions as activator and repressor at these distinct developmental stages. Results We report that the kinase PKCα triggers Kr-h1 phosphorylation at the amino acid residue Ser154, a step essential for its dual functions. During juvenile stage, phosphorylated Kr-h1 recruits a corepressor, C-terminal binding protein (CtBP). The complex of phosphorylated Kr-h1 and CtBP represses the transcription of Ecdysone induced protein 93F (E93) and consequently prevents the juvenile-to-adult transition. In adult insects, phosphorylated Kr-h1 recruits a coactivator, CREB-binding protein (CBP), and promotes vitellogenesis by inducing the expression of Ribosomal protein L36. Furthermore, Kr-h1 phosphorylation with the concomitant inhibition of E93 transcription is evolutionarily conserved across insect orders. Conclusion Our results suggest that Kr-h1 phosphorylation is indispensable for the recruitment of transcriptional cofactors, and for its anti-metamorphic and vitellogenic actions in insects. Our data shed new light on the understanding of Kr-h1 regulation and function in JH-regulated insect metamorphosis and reproduction. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01157-3.
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Affiliation(s)
- Zhongxia Wu
- State Key Laboratory of Cotton Biology, Key Laboratory of Plant Stress Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Libin Yang
- State Key Laboratory of Cotton Biology, Key Laboratory of Plant Stress Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Huihui Li
- State Key Laboratory of Cotton Biology, Key Laboratory of Plant Stress Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Shutang Zhou
- State Key Laboratory of Cotton Biology, Key Laboratory of Plant Stress Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China.
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13
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Suzuki Y, Toh L. Constraints and Opportunities for the Evolution of Metamorphic Organisms in a Changing Climate. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.734031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We argue that developmental hormones facilitate the evolution of novel phenotypic innovations and timing of life history events by genetic accommodation. Within an individual’s life cycle, metamorphic hormones respond readily to environmental conditions and alter adult phenotypes. Across generations, the many effects of hormones can bias and at times constrain the evolution of traits during metamorphosis; yet, hormonal systems can overcome constraints through shifts in timing of, and acquisition of tissue specific responses to, endocrine regulation. Because of these actions of hormones, metamorphic hormones can shape the evolution of metamorphic organisms. We present a model called a developmental goblet, which provides a visual representation of how metamorphic organisms might evolve. In addition, because developmental hormones often respond to environmental changes, we discuss how endocrine regulation of postembryonic development may impact how organisms evolve in response to climate change. Thus, we propose that developmental hormones may provide a mechanistic link between climate change and organismal adaptation.
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Mayfly metamorphosis: Adult winged insects that molt. Proc Natl Acad Sci U S A 2021; 118:2114128118. [PMID: 34521757 DOI: 10.1073/pnas.2114128118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2021] [Indexed: 11/18/2022] Open
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15
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Regulation of metamorphosis in neopteran insects is conserved in the paleopteran Cloeon dipterum (Ephemeroptera). Proc Natl Acad Sci U S A 2021; 118:2105272118. [PMID: 34417295 DOI: 10.1073/pnas.2105272118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In the Paleozoic era, more than 400 Ma, a number of insect groups continued molting after forming functional wings. Today, however, flying insects stop molting after metamorphosis when they become fully winged. The only exception is the mayflies (Paleoptera, Ephemeroptera), which molt in the subimago, a flying stage between the nymph and the adult. However, the identity and homology of the subimago still is underexplored. Debate remains regarding whether this stage represents a modified nymph, an adult, or a pupa like that of butterflies. Another relevant question is why mayflies have the subimago stage despite the risk of molting fragile membranous wings. These questions have intrigued numerous authors, but nonetheless, clear answers have not yet been found. By combining morphological studies, hormonal treatments, and molecular analysis in the mayfly Cloeon dipterum, we found answers to these old questions. We observed that treatment with a juvenile hormone analog in the last nymphal instar stimulated the expression of the Kr-h1 gene and reduced that of E93, which suppress and trigger metamorphosis, respectively. The regulation of metamorphosis thus follows the MEKRE93 pathway, as in neopteran insects. Moreover, the treatment prevented the formation of the subimago. These findings suggest that the subimago must be considered an instar of the adult mayfly. We also observed that the forelegs dramatically grow between the last nymphal instar, the subimago, and the adult. This necessary growth spread over the last two stages could explain, at least in part, the adaptive sense of the subimago.
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Kamsoi O, Belles X. E93-depleted adult insects preserve the prothoracic gland and molt again. Development 2020; 147:dev.190066. [PMID: 33077428 DOI: 10.1242/dev.190066] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 10/13/2020] [Indexed: 01/05/2023]
Abstract
Insect metamorphosis originated around the middle Devonian, associated with the innovation of the final molt; this occurs after histolysis of the prothoracic gland (PG; which produces the molting hormone) in the first days of adulthood. We previously hypothesized that transcription factor E93 is crucial in the emergence of metamorphosis, because it triggers metamorphosis in extant insects. This work on the cockroach Blattella germanica reveals that E93 also plays a crucial role in the histolysis of PG, which fits the above hypothesis. Previous studies have shown that the transcription factor FTZ-F1 is essential for PG histolysis. We have found that FTZ-F1 depletion towards the end of the final nymphal instar downregulates the expression of E93, whereas E93-depleted nymphs molt to adults that retain a functional PG. Interestingly, these adults are able to molt again, which is exceptional in insects. The study of insects able to molt again in the adult stage may reveal clues about how nymphal epidermal cells definitively become adult cells, and whether it is possible to reverse this process.
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Affiliation(s)
- Orathai Kamsoi
- Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Passeig Maritim 37, 08003 Barcelona, Spain
| | - Xavier Belles
- Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Passeig Maritim 37, 08003 Barcelona, Spain
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17
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Chou A, Lin C, Cronin TW. Visual metamorphoses in insects and malacostracans: Transitions between an aquatic and terrestrial life. ARTHROPOD STRUCTURE & DEVELOPMENT 2020; 59:100974. [PMID: 32822960 DOI: 10.1016/j.asd.2020.100974] [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: 03/20/2020] [Revised: 07/05/2020] [Accepted: 07/10/2020] [Indexed: 06/11/2023]
Abstract
Arthropods operate in an outrageous diversity of environments. From the deep sea to dense tropical forests, to wide open arctic tundra, they have colonized almost every possible habitat. Within these environments, the presence of light is nearly ubiquitous, varying in intensity, wavelength, and polarization. Light provides critical information about the environment, such as time of day or where food sources may be located. Animals take advantage of this prevalent and informative cue to make behavioral choices. However, the types of choices animals face depend greatly on their environments and needs at any given time. In particular, animals that undergo metamorphosis, with arthropods being the prime example, experience dramatic changes in both behavior and ecology, which in turn may require altering the structure and function of sensory systems such as vision. Amphibiotic organisms maintain aquatic lifestyles as juveniles before transitioning to terrestrial lifestyles as adults. However, light behaves differently in water than in air, resulting in distinct aquatic and terrestrial optical environments. Visual changes in response to these optical differences can occur on multiple levels, from corneal structure down to neural organization. In this review, we summarize examples of alterations in the visual systems of amphibiotic larval and adult insects and malacostracan crustaceans, specifically those attributed to environmental differences between metamorphic phases.
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Affiliation(s)
- Alice Chou
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA.
| | - Chan Lin
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA; Department of Invertebrate Zoology, Smithsonian National Museum of Natural History, Washington, DC, 20560, USA
| | - Thomas W Cronin
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA
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18
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Abstract
The evolution of insect metamorphosis is one of the most important sagas in animal history, transforming small, obscure soil arthropods into a dominant terrestrial group that has profoundly shaped the evolution of terrestrial life. The evolution of flight initiated the trajectory towards metamorphosis, favoring enhanced differences between juvenile and adult stages. The initial step modified postembryonic development, resulting in the nymph-adult differences characteristic of hemimetabolous species. The second step was to complete metamorphosis, holometaboly, and occurred by profoundly altering embryogenesis to produce a larval stage, the nymph becoming the pupa to accommodate the deferred development needed to make the adult. These changing life history patterns were intimately linked to two hormonal systems, the ecdysteroids and the juvenile hormones (JH), which function in both embryonic and postembryonic domains and control the stage-specifying genes Krüppel homolog 1 (Kr-h1), broad and E93. The ecdysteroids induce and direct molting through the ecdysone receptor (EcR), a nuclear hormone receptor with numerous targets including a conserved transcription factor network, the 'Ashburner cascade', which translates features of the ecdysteroid peak into the different phases of the molt. With the evolution of metamorphosis, ecdysteroids acquired a metamorphic function that exploited the repressor capacity of the unliganded EcR, making it a hormone-controlled gateway for the tissue development preceding metamorphosis. JH directs ecdysteroid action, controlling Kr-h1 expression which in turn regulates the other stage-specifying genes. JH appears in basal insect groups as their embryos shift from growth and patterning to differentiation. As a major portion of embryogenesis was deferred to postembryonic life with the evolution of holometaboly, JH also acquired a potent role in regulating postembryonic growth and development. Details of its involvement in broad expression and E93 suppression have been modified as life cycles became more complex and likely underlie some of the changes seen in the shift from incomplete to complete metamorphosis.
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Affiliation(s)
- James W Truman
- Department of Biology and Friday Harbor Laboratories, University of Washington, 620 University Road, Friday Harbor, WA 98250, USA.
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19
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Genomic adaptations to aquatic and aerial life in mayflies and the origin of insect wings. Nat Commun 2020; 11:2631. [PMID: 32457347 PMCID: PMC7250882 DOI: 10.1038/s41467-020-16284-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 04/27/2020] [Indexed: 01/11/2023] Open
Abstract
The evolution of winged insects revolutionized terrestrial ecosystems and led to the largest animal radiation on Earth. However, we still have an incomplete picture of the genomic changes that underlay this diversification. Mayflies, as one of the sister groups of all other winged insects, are key to understanding this radiation. Here, we describe the genome of the mayfly Cloeon dipterum and its gene expression throughout its aquatic and aerial life cycle and specific organs. We discover an expansion of odorant-binding-protein genes, some expressed specifically in breathing gills of aquatic nymphs, suggesting a novel sensory role for this organ. In contrast, flying adults use an enlarged opsin set in a sexually dimorphic manner, with some expressed only in males. Finally, we identify a set of wing-associated genes deeply conserved in the pterygote insects and find transcriptomic similarities between gills and wings, suggesting a common genetic program. Globally, this comprehensive genomic and transcriptomic study uncovers the genetic basis of key evolutionary adaptations in mayflies and winged insects. Genomic studies of paleopteran insects, such as mayflies, are needed to reconstruct early insect evolution. Here, Almudi and colleagues present the genome of the mayfly Cloeon dipterum and use transcriptomics to characterize its adaptations to distinct habitats and the origin of insect wings.
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Heneberg P, Bogusch P, Astapenková A, Řezáč M. Neonicotinoid insecticides hinder the pupation and metamorphosis into adults in a crabronid wasp. Sci Rep 2020; 10:7077. [PMID: 32341495 PMCID: PMC7184726 DOI: 10.1038/s41598-020-63958-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 04/03/2020] [Indexed: 12/21/2022] Open
Abstract
Neonicotinoid insecticides are associated with a decline in the diversity and distribution of bees and wasps (Hymenoptera: Aculeata). The effects of neonicotinoids on the metamorphosis of aculeates have never been addressed in detail; however, recent evidence suggests that neonicotinoids induce wing abnormalities. We hypothesized that the metamorphosis success of bees and wasps differs in response to contact exposure to field-realistic concentrations of neonicotinoid insecticides or in response to combined exposure to neonicotinoid insecticides and benzimidazole fungicides. We treated prepupae of the model crabronid wasp Pemphredon fabricii with field-realistic concentrations of four neonicotinoids, acetamiprid, imidacloprid, thiacloprid and thiamethoxam, and/or with the benzimidazole fungicide thiabendazole. Treatment with acetamiprid or imidacloprid decreased the pupation rates to only 39% and 32%, respectively. Treatment with thiacloprid or thiamethoxam did not affect the pupation rate when applied alone, but the subsequent treatment of thiacloprid- or thiamethoxam-treated prepupae with thiabendazole led to significant decreases in pupation rates. A high concentration of acetamiprid, which severely affected the pupation rates, had moderate effects on metamorphosis into adults, resulting in 53% metamorphosis success (as opposed to 95% metamorphosis success in the water-treated group). However, imidacloprid or thiamethoxam treatment resulted in only 5%-10% metamorphosis success into adults. Overall survival decreased in response to treatment with any of the neonicotinoids or benzimidazoles or their combinations, with extremely low survival (<2%) following combined treatment with imidacloprid and thiabendazole or thiamethoxam and thiabendazole. In conclusion, neonicotinoids alter insect metamorphosis success, which can be further potentiated by their combination with other agrochemicals, such as benzimidazoles.
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Affiliation(s)
- Petr Heneberg
- Charles University, Third Faculty of Medicine, Prague, Czech Republic.
| | - Petr Bogusch
- University of Hradec Králové, Faculty of Science, Hradec Králové, Czech Republic
| | - Alena Astapenková
- University of Hradec Králové, Faculty of Science, Hradec Králové, Czech Republic
| | - Milan Řezáč
- Crop Research Institute, Functional Biodiversity Group, Prague, Czech Republic
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21
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Rolff J, Johnston PR, Reynolds S. Complete metamorphosis of insects. Philos Trans R Soc Lond B Biol Sci 2019; 374:20190063. [PMID: 31438816 DOI: 10.1098/rstb.2019.0063] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The majority of described hexapod species are holometabolous insects, undergoing an extreme form of metamorphosis with an intercalated pupal stage between the larva and adult, in which organs and tissues are extensively remodelled and in some cases completely rebuilt. Here, we review how and why this developmental strategy has evolved. While there are many theories explaining the evolution of metamorphosis, many of which fit under the hypothesis of decoupling of life stages, there are few clear adaptive hypotheses on why complete metamorphosis evolved. We propose that the main adaptive benefit of complete metamorphosis is decoupling between growth and differentiation. This facilitates the exploitation of ephemeral resources and enhances the probability of the metamorphic transition escaping developmental size thresholds. The evolution of complete metamorphosis comes at the cost of exposure to predators, parasites and pathogens during pupal life and requires specific adaptations of the immune system at this time. Moreover, metamorphosis poses a challenge for the maintenance of symbionts and the gut microbiota, although it may also offer the benefit of allowing an extensive change in microbiota between the larval and adult stages. The regulation of metamorphosis by two main players, ecdysone and juvenile hormone, and the related signalling cascades are now relatively well understood. The mechanics of metamorphosis have recently been studied in detail because of the advent of micro-CT and research into the role of cell death in remodelling tissues and organs. We support the argument that the adult stage must necessarily have preceded the larval form of the insect. We do not resolve the still contentious question of whether the larva of insects in general originated through the modification of existing preadult forms or through heterochrony as a modified embryonic stage (pronymph), nor whether the holometabolous pupa arose as a modified hemimetabolous final stage larva. This article is part of the theme issue 'The evolution of complete metamorphosis'.
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Affiliation(s)
- Jens Rolff
- Evolutionary Biology, Institut für Biologie, Freie Universität Berlin, Berlin, Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
| | - Paul R Johnston
- Evolutionary Biology, Institut für Biologie, Freie Universität Berlin, Berlin, Germany.,Berlin Center for Genomics in Biodiversity Research, Berlin, Germany.,Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
| | - Stuart Reynolds
- Department of Biology and Biochemistry, University of Bath, Bath, UK
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22
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Tettamanti G, Casartelli M. Cell death during complete metamorphosis. Philos Trans R Soc Lond B Biol Sci 2019; 374:20190065. [PMID: 31438818 DOI: 10.1098/rstb.2019.0065] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In insects that undergo complete metamorphosis, cell death is essential for reshaping or removing larval tissues and organs, thus contributing to formation of the adult's body structure. In the last few decades, the study of metamorphosis in Lepidoptera and Diptera has provided broad information on the tissue remodelling processes that occur during larva-pupa-adult transition and made it possible to unravel the underlying regulatory pathways. This review summarizes recent knowledge on cell death mechanisms in Lepidoptera and other holometabolous insects, highlighting similarities and differences with Drosophila melanogaster, and discusses the role of apoptosis and autophagy in this developmental setting. This article is part of the theme issue 'The evolution of complete metamorphosis'.
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Affiliation(s)
- Gianluca Tettamanti
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy
| | - Morena Casartelli
- Department of Biosciences, University of Milano, 20133 Milano, Italy
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Reynolds S. Cooking up the perfect insect: Aristotle's transformational idea about the complete metamorphosis of insects. Philos Trans R Soc Lond B Biol Sci 2019; 374:20190074. [PMID: 31438815 DOI: 10.1098/rstb.2019.0074] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Aristotle made important contributions to the study of developmental biology, including the complete metamorphosis of insects. One concept in particular, that of the perfect or complete state, underlies Aristotle's ideas about metamorphosis, the necessity of fertilization for embryonic development, and whether morphogenesis involves an autonomous process of self-assembly. Importantly, the philosopher erroneously views metamorphosis as a necessary developmental response to lack of previous fertilization of the female parent, a view that is intimately connected with his readiness to accept the idea of the spontaneous generation of life. Aristotle's work underpins that of the major seventeenth century students of metamorphosis, Harvey, Redi, Malpighi and Swammerdam, all of whom make frequent reference to Aristotle in their writings. Although both Aristotle and Harvey are often credited with inspiring the later prolonged debate between proponents of epigenesis and preformation, neither actually held firm views on the subject. Aristotle's idea of the perfect stage also underlies his proposal that the eggs of holometabolous insects hatch 'before their time', an idea that is the direct precursor of the much later proposals by Lubbock and Berlese that the larval stages of holometabolous insects are due to the 'premature hatching' from the egg of an imperfect embryonic stage. This article is part of the theme issue 'The evolution of complete metamorphosis'.
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Affiliation(s)
- Stuart Reynolds
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
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24
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Johnston PR, Paris V, Rolff J. Immune gene regulation in the gut during metamorphosis in a holo- versus a hemimetabolous insect. Philos Trans R Soc Lond B Biol Sci 2019; 374:20190073. [PMID: 31438821 DOI: 10.1098/rstb.2019.0073] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
During metamorphosis, holometabolous insects completely replace the larval gut and must control the microbiota to avoid septicaemia. Rapid induction of bactericidal activity in the insect gut at the onset of pupation has been described in numerous orders of the Holometabola and is best-studied in the Lepidoptera where it is under control of the 20-hydroxyecdysone (20E) moulting pathway. Here, using RNAseq, we compare the expression of immune effector genes in the gut during metamorphosis in a holometabolous (Galleria mellonella) and a hemimetabolous insect (Gryllus bimaculatus). We find that in G. mellonella, the expression of numerous immune effectors and the transcription factor GmEts are upregulated, with peak expression of three antimicrobial peptides (AMPs) and a lysozyme coinciding with delamination of the larval gut. By contrast, no such upregulation was detectable in the hemimetabolous Gr. bimaculatus. These findings support the idea that the upregulation of immune effectors at the onset of complete metamorphosis is an adaptive response, which controls the microbiota during gut replacement. This article is part of the theme issue 'The evolution of complete metamorphosis'.
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Affiliation(s)
- Paul R Johnston
- Berlin Center for Genomics in Biodiversity Research, Berlin, Germany.,Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
| | - Véronique Paris
- Evolutionary Biology, Institut für Biologie, Freie Universität Berlin, Berlin, Germany.,Bio 21 Institute, University of Melbourne, Parkville VIC 3052, Australia
| | - Jens Rolff
- Evolutionary Biology, Institut für Biologie, Freie Universität Berlin, Berlin, Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
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Ishimaru Y, Tomonari S, Watanabe T, Noji S, Mito T. Regulatory mechanisms underlying the specification of the pupal-homologous stage in a hemimetabolous insect. Philos Trans R Soc Lond B Biol Sci 2019; 374:20190225. [PMID: 31438810 DOI: 10.1098/rstb.2019.0225] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Juvenile hormones and the genetic interaction between the transcription factors Krüppel homologue 1 (Kr-h1) and Broad (Br) regulate the transformation of insects from immature to adult forms in both types of metamorphosis (holometaboly with a pupal stage versus hemimetaboly with no pupal stage); however, knowledge about the exact instar in which this occurs is limited. Using the hemimetabolous cricket Gryllus bimaculatus (Gb), we demonstrate that a genetic interaction occurs among Gb'Kr-h1, Gb'Br and the adult-specifier transcription factor Gb'E93 from the sixth to final (eighth) nymphal instar. Gb'Kr-h1 and Gb'Br mRNAs were strongly expressed in the abdominal tissues of sixth instar nymphs, with precocious adult moults being induced by Gb'Kr-h1 or Gb'Br knockdown in the sixth instar. The depletion of Gb'Kr-h1 or Gb'Br upregulates Gb'E93 in the sixth instar. By contrast, Gb'E93 knockdown at the sixth instar prevents nymphs transitioning to adults, instead producing supernumerary nymphs. Gb'E93 also represses Gb'Kr-h1 and Gb'Br expression in the penultimate nymphal instar, demonstrating its important role in adult differentiation. Our results suggest that the regulatory mechanisms underlying the pupal transition in holometabolous insects are evolutionarily conserved in hemimetabolous G. bimaculatus, with the penultimate and final nymphal periods being equivalent to the pupal stage. This article is part of the theme issue 'The evolution of complete metamorphosis'.
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Affiliation(s)
- Yoshiyasu Ishimaru
- Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minami-Jyosanjima-cho, Tokushima City, Tokushima 770-8513, Japan
| | - Sayuri Tomonari
- Division of Chemical and Physical Analyses, Center for Technical Support, Institute of Technology and Science, Tokushima University, 2-1 Minami-Jyosanjima-cho, Tokushima City, Tokushima 770-8506, Japan
| | - Takahito Watanabe
- Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minami-Jyosanjima-cho, Tokushima City, Tokushima 770-8513, Japan
| | - Sumihare Noji
- Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minami-Jyosanjima-cho, Tokushima City, Tokushima 770-8513, Japan
| | - Taro Mito
- Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minami-Jyosanjima-cho, Tokushima City, Tokushima 770-8513, Japan
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Jindra M. Where did the pupa come from? The timing of juvenile hormone signalling supports homology between stages of hemimetabolous and holometabolous insects. Philos Trans R Soc Lond B Biol Sci 2019; 374:20190064. [PMID: 31438814 DOI: 10.1098/rstb.2019.0064] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Insect metamorphosis boasts spectacular cases of postembryonic development when juveniles undergo massive morphogenesis before attaining the adult form and function; in moths or flies the larvae do not even remotely resemble their adult parents. A selective advantage of complete metamorphosis (holometaboly) is that within one species the two forms with different lifestyles can exploit diverse habitats. It was the environmental adaptation and specialization of larvae, primarily the delay and internalization of wing development, that eventually required an intermediate stage that we call a pupa. It is a long-held and parsimonious hypothesis that the holometabolous pupa evolved through modification of a final juvenile stage of an ancestor developing through incomplete metamorphosis (hemimetaboly). Alternative hypotheses see the pupa as an equivalent of all hemimetabolous moulting cycles (instars) collapsed into one, and consider any preceding holometabolous larval instars free-living embryos stalled in development. Discoveries on juvenile hormone signalling that controls metamorphosis grant new support to the former hypothesis deriving the pupa from a final pre-adult stage. The timing of expression of genes that repress and promote adult development downstream of hormonal signals supports homology between postembryonic stages of hemimetabolous and holometabolous insects. This article is part of the theme issue 'The evolution of complete metamorphosis'.
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Affiliation(s)
- Marek Jindra
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice 370 05, Czech Republic
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27
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Lindstedt C, Murphy L, Mappes J. Antipredator strategies of pupae: how to avoid predation in an immobile life stage? Philos Trans R Soc Lond B Biol Sci 2019; 374:20190069. [PMID: 31438812 DOI: 10.1098/rstb.2019.0069] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Antipredator strategies of the pupal stage in insects have received little attention in comparison to larval or adult stages. This is despite the fact that predation risk can be high during the pupal stage, making it a critical stage for subsequent fitness. The immobile pupae are not, however, defenceless; a wide range of antipredator strategies have evolved against invertebrate and vertebrate predators. The most common strategy seems to be 'avoiding encounters with predators' by actively hiding in vegetation and soil or via cryptic coloration and masquerade. Pupae have also evolved behavioural and secondary defences such as defensive toxins, physical defences or deimatic movements and sounds. Interestingly, warning coloration used to advertise unprofitability has evolved very rarely, even though the pupal stage often contains defensive toxins in chemically defended species. In some species, pupae gain protection from conspecifics or mimic chemical and auditory signals and thereby manipulate other species to protect them. Our literature survey highlights the importance of studying selection pressures across an individual's life stages to predict how ontogenetic variation in selective environments shapes individual fitness and population dynamics in insects. Finally, we also suggest interesting avenues for future research to pursue. This article is part of the theme issue 'The evolution of complete metamorphosis'.
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Affiliation(s)
- Carita Lindstedt
- Department of Biological and Environmental Sciences, P.O. Box 35, FI-40014 University of Jyväskylä, Jyväskylä, Finland
| | - Liam Murphy
- Department of Biological and Environmental Sciences, P.O. Box 35, FI-40014 University of Jyväskylä, Jyväskylä, Finland
| | - Johanna Mappes
- Department of Biological and Environmental Sciences, P.O. Box 35, FI-40014 University of Jyväskylä, Jyväskylä, Finland
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