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Erezyilmaz D. The genetic determination of alternate stages in polyphenic insects. Evol Dev 2024:e12485. [PMID: 38867484 DOI: 10.1111/ede.12485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 02/23/2024] [Accepted: 05/14/2024] [Indexed: 06/14/2024]
Abstract
Molt-based transitions in form are a central feature of insect life that have enabled adaptation to diverse and changing environments. The endocrine regulation of these transitions is well established, but an understanding of their genetic regulation has only recently emerged from insect models. The pupal and adult stages of metamorphosing insects are determined by the stage specifying transcription factors broad-complex (br) and Ecdysone inducible protein 93 (E93), respectively. A probable larval determinant, chronologically inappropriate metamorphosis (chinmo), has just recently been characterized. Expression of these three transcription factors in the metamorphosing insects is regulated by juvenile hormone with ecdysteroid hormones, and by mutual repression between the stage-specific transcription factors. This review explores the hypothesis that variations in the onset, duration, and tissue-specific expression of chinmo, br, and E93 underlie other polyphenisms that have arisen throughout insects, including the castes of social insects, aquatic stages of mayflies, and the neoteny of endoparasites. The mechanisms that constrain how chinmo, br, and E93 expression may vary will also constrain the ways that insect life history may evolve. I find that four types of expression changes are associated with novel insect forms: (1) heterochronic shift in the turnover of expression, (2) expansion or contraction of expression, (3) tissue-specific expression, and (4) redeployment of stage-specific expression. While there is more to be learned about chinmo, br, and E93 function in diverse insect taxa, the studies outlined here show that insect stages are modular units in developmental time and a substrate for evolutionary forces to act upon.
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Affiliation(s)
- Deniz Erezyilmaz
- Department of Physiology, Anatomy and Genetics, Centre for Neural Circuits and Behavior, University of Oxford, Oxford, UK
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2
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Oguchi K, Miura T. Body part-specific development in termite caste differentiation: crosstalk between hormonal actions and developmental toolkit genes. CURRENT OPINION IN INSECT SCIENCE 2024; 63:101183. [PMID: 38428818 DOI: 10.1016/j.cois.2024.101183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 02/24/2024] [Accepted: 02/25/2024] [Indexed: 03/03/2024]
Abstract
In social insects, interactions among colony members trigger caste differentiation with morphological modifications. During caste differentiation in termites, body parts and caste-specific morphologies are modified during postembryonic development under endocrine controls such as juvenile hormone (JH) and ecdysone. In addition to endocrine factors, developmental toolkit genes such as Hox- and appendage-patterning genes also contribute to the caste-specific body part modifications. These toolkits are thought to provide spatial information for specific morphogenesis. During social evolution, the complex crosstalks between physiological and developmental mechanisms should be established, leading to the sophisticated caste systems. This article reviews recent studies on these mechanisms underlying the termite caste differentiation and addresses implications for the evolution of caste systems in termites.
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Affiliation(s)
- Kohei Oguchi
- Misaki Marine Biological Station, The University of Tokyo, Miura, Kanagawa 238-0225, Japan
| | - Toru Miura
- Misaki Marine Biological Station, The University of Tokyo, Miura, Kanagawa 238-0225, Japan.
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3
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Fujiwara K, Miyazaki S, Maekawa K. Candidate target genes of the male-specific expressed Doublesex in the termite Reticulitermes speratus. PLoS One 2024; 19:e0299900. [PMID: 38427681 PMCID: PMC10906832 DOI: 10.1371/journal.pone.0299900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 02/17/2024] [Indexed: 03/03/2024] Open
Abstract
Eusocial insects such as termites, ants, bees, and wasps exhibit a reproductive division of labor. The developmental regulation of reproductive organ (ovaries and testes) is crucial for distinguishing between reproductive and sterile castes. The development of reproductive organ in insects is regulated by sex-determination pathways. The sex determination gene Doublesex (Dsx), encoding transcription factors, plays an important role in this pathway. Therefore, clarifying the function of Dsx in the developmental regulation of sexual traits is important to understand the social evolution of eusocial insects. However, no studies have reported the function of Dsx in hemimetabolous eusocial group termites. In this study, we searched for binding sites and candidate target genes of Dsx in species with available genome information as the first step in clarifying the function of Dsx in termites. First, we focused on the Reticulitermes speratus genome and identified 101 candidate target genes of Dsx. Using a similar method, we obtained 112, 39, and 76 candidate Dsx target genes in Reticulitermes lucifugus, Coptotermes formosanus, and Macrotermes natalensis, respectively. Second, we compared the candidate Dsx target genes between species and identified 37 common genes between R. speratus and R. lucifugus. These included several genes probably involved in spermatogenesis and longevity. However, only a few common target genes were identified between R. speratus and the other two species. Finally, Dsx dsRNA injection resulted in the differential expression of several target genes, including piwi-like protein and B-box type zinc finger protein ncl-1 in R. speratus. These results provide valuable resource data for future functional analyses of Dsx in termites.
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Affiliation(s)
- Kokuto Fujiwara
- Graduate School of Science and Engineering, University of Toyama, Gofuku, Toyama, Japan
| | - Satoshi Miyazaki
- Graduate School of Agriculture, Tamagawa University, Machida, Tokyo, Japan
| | - Kiyoto Maekawa
- Academic Assembly, University of Toyama, Gofuku, Toyama, Japan
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Fujiwara K, Karasawa A, Hanada T, Tobo M, Kaneko T, Usui M, Maekawa K. Caste-specific expressions and diverse roles of takeout genes in the termite Reticulitermes speratus. Sci Rep 2023; 13:8422. [PMID: 37225771 DOI: 10.1038/s41598-023-35524-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 05/19/2023] [Indexed: 05/26/2023] Open
Abstract
Acquisition of novel functions caused by gene duplication may be important for termite social evolution. To clarify this possibility, additional evidence is needed. An important example is takeout, encoding juvenile hormone binding protein. We identified 25 takeouts in the termite Reticulitermes speratus genome. RNA-seq revealed that many genes were highly expressed in specific castes. Two novel paralogs (RsTO1, RsTO2) were tandemly aligned in the same scaffold. Real-time qPCR indicated that RsTO1 and RsTO2 were highly expressed in queens and soldiers, respectively. Moreover, the highest RsTO1 expression was observed in alates during queen formation. These patterns were different from vitellogenins, encoding egg-yolk precursors, which were highly expressed in queens than alates. In situ hybridization showed that RsTO1 mRNA was localized in the alate-frontal gland, indicating that RsTO1 binds with secretions probably used for the defence during swarming flight. In contrast, increased RsTO2 expression was observed approximately 1 week after soldier differentiation. Expression patterns of geranylgeranyl diphosphate synthase, whose product functions in the terpenoid synthesis, were similar to RsTO2 expression. In situ hybridization indicated RsTO2-specific mRNA signals in the soldier-frontal gland. RsTO2 may interact with terpenoids, with a soldier-specific defensive function. It may provide additional evidence for functionalization after gene duplication in termites.
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Affiliation(s)
- Kokuto Fujiwara
- Graduate School of Science and Engineering, University of Toyama, Gofuku, Toyama, 930-8555, Japan
| | - Akimi Karasawa
- Department of Biology, Faculty of Science, University of Toyama, Gofuku, Toyama, 930-8555, Japan
| | - Takumi Hanada
- Graduate School of Science and Engineering, University of Toyama, Gofuku, Toyama, 930-8555, Japan
| | - Mutsuaki Tobo
- Graduate School of Science and Engineering, University of Toyama, Gofuku, Toyama, 930-8555, Japan
| | - Tousuke Kaneko
- Department of Biology, Faculty of Science, University of Toyama, Gofuku, Toyama, 930-8555, Japan
| | - Mizuna Usui
- Department of Biology, Faculty of Science, University of Toyama, Gofuku, Toyama, 930-8555, Japan
| | - Kiyoto Maekawa
- Faculty of Science, Academic Assembly, University of Toyama, Gofuku, Toyama, 930-8555, Japan.
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Suzuki R, Masuoka Y, Suzuki RH, Maekawa K. Efficient RNA interference method during caste differentiation with hormone treatment in the termite Reticulitermes speratus (Isoptera: Rhinotermitidae). FRONTIERS IN INSECT SCIENCE 2023; 3:1188343. [PMID: 38469474 PMCID: PMC10926471 DOI: 10.3389/finsc.2023.1188343] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 04/24/2023] [Indexed: 03/13/2024]
Abstract
Unveiling the proximate mechanism of caste differentiation is crucial for understanding insect social evolution, and gene function analysis is an important tool in this endeavor. The RNA interference (RNAi) technique is useful in termites, but its knockdown effects may differ among species. One of the most important model species in the field of termite sociogenomics is Reticulitermes speratus Kolbe (Isoptera: Rhinotermitidae). Presoldier and worker differentiation of this species can be artificially induced by juvenile hormone and 20-hydroxyecdysone application, respectively. However, appropriate RNAi technique of genes expressed during caste differentiation has never been considered. To clarify this issue, first, we injected nine different volumes of nuclease-free water (NFW, 0-404.8 nL) into workers and found that survival and caste differentiation rates were strongly reduced by the application of the top three largest volumes. Second, we injected double-stranded (ds) RNA of ecdysone receptor homolog (RsEcR) (2.0 µg/151.8 nL NFW) into workers with hormone treatments. The expression levels of RsEcR were significantly reduced at 9 days after dsRNA injection. RsEcR RNAi strongly affected both molting events during presoldier and worker differentiation induced by hormone treatments. The present results highlight the need for caution regarding injection volumes for RNAi experiments using hormone treatments. We suggest that the injection of dsRNA solution (2 µg; approximately 100-200 nL) is suitable for RNAi experiments during caste differentiation induced by hormone application in R. speratus.
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Affiliation(s)
- Ryutaro Suzuki
- Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
- Ishikawa Insect Museum, Hakusan, Japan
| | - Yudai Masuoka
- Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Ryohei H. Suzuki
- Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
- Research and Development Headquarters, Earth Corporation, Ltd. Ako, Japan
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Toga K, Bono H. Meta-Analysis of Public RNA Sequencing Data Revealed Potential Key Genes Associated with Reproductive Division of Labor in Social Hymenoptera and Termites. Int J Mol Sci 2023; 24:ijms24098353. [PMID: 37176060 PMCID: PMC10179490 DOI: 10.3390/ijms24098353] [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: 04/18/2023] [Accepted: 05/04/2023] [Indexed: 05/15/2023] Open
Abstract
Eusociality in insects has evolved independently many times. One of the most notable characteristics of eusociality is the reproductive division of labor. In social insects, the reproductive division of labor is accomplished by queens and workers. Transcriptome analyses of queens and workers have been conducted for various eusocial species. However, the genes that regulate the reproductive division of labor across all or multiple eusocial species have not yet been fully elucidated. Therefore, we conducted a meta-analysis using publicly available RNA-sequencing data from four major groups of social insects. In this meta-analysis, we collected 258 pairs (queen vs. worker) of RNA-sequencing data from 34 eusocial species. The meta-analysis identified a total of 20 genes that were differentially expressed in queens or workers. Out of these, 12 genes have not previously been reported to be involved in the reproductive division of labor. Functional annotation of these 20 genes in other organisms revealed that they could be regulators of behaviors and physiological states related to the reproductive division of labor. These 20 genes, revealed using massive datasets of numerous eusocial insects, may be key regulators of the reproductive division of labor.
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Affiliation(s)
- Kouhei Toga
- Laboratory of BioDX, PtBio Co-Creation Research Center, Genome Editing Innovation Center, Hiroshima University, 3-10-23 Kagamiyama, Higashi-Hiroshima City 739-0046, Hiroshima, Japan
- Laboratory of Genome Informatics, Graduate School of Integrated Sciences for Life, Hiroshima University, 3-10-23 Kagamiyama, Higashi-Hiroshima City 739-0046, Hiroshima, Japan
| | - Hidemasa Bono
- Laboratory of BioDX, PtBio Co-Creation Research Center, Genome Editing Innovation Center, Hiroshima University, 3-10-23 Kagamiyama, Higashi-Hiroshima City 739-0046, Hiroshima, Japan
- Laboratory of Genome Informatics, Graduate School of Integrated Sciences for Life, Hiroshima University, 3-10-23 Kagamiyama, Higashi-Hiroshima City 739-0046, Hiroshima, Japan
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Yaguchi H, Suzuki S, Kanasaki N, Masuoka Y, Suzuki R, Suzuki RH, Hayashi Y, Shigenobu S, Maekawa K. Evolution and functionalization of vitellogenin genes in the termite Reticulitermes speratus. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2023; 340:68-80. [PMID: 35485990 DOI: 10.1002/jez.b.23141] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 03/22/2022] [Accepted: 04/08/2022] [Indexed: 12/16/2022]
Abstract
Eusociality has been commonly observed in distinct animal lineages. The reproductive division of labor is a particular feature, achieved by the coordination between fertile and sterile castes within the same nest. The sociogenomic approach in social hymenopteran insects indicates that vitellogenin (Vg) has undergone neo-functionalization in sterile castes. Here, to know whether Vgs have distinct roles in nonreproductive castes in termites, we investigated the unique characteristics of Vgs in the rhinotermitid termite Reticulitermes speratus. The four Vgs were identified from R. speratus (RsVg1-4), and RsVg3 sequences were newly identified using the RACE method. Molecular phylogenetic analysis supported the monophyly of the four termite Vgs. Moreover, the termites Vg1-3 and Vg4 were positioned in two different clades. The dN/dS ratios indicated that the branch leading to the common ancestor of termite Vg4 was under weak purifying selection. Expression analyses among castes (reproductives, workers, and soldiers) and females (nymphs, winged alates, and queens) showed that RsVg1-3 was highly expressed in fertile queens. In contrast, RsVg4 was highly expressed in workers and female nonreproductives (nymphs and winged adults). Localization of RsVg4 messenger RNA was confirmed in the fat body of worker heads and abdomens. These results suggest that Vg genes are functionalized after gene duplication during termite eusocial transition and that Vg4 is involved in nonreproductive roles in termites.
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Affiliation(s)
- Hajime Yaguchi
- Graduate School of Science and Engineering, University of Toyama, Gofuku, Toyama, Japan.,Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Japan.,Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan
| | - Shogo Suzuki
- Graduate School of Science and Engineering, University of Toyama, Gofuku, Toyama, Japan
| | - Naoto Kanasaki
- Graduate School of Science and Engineering, University of Toyama, Gofuku, Toyama, Japan
| | - Yudai Masuoka
- Graduate School of Science and Engineering, University of Toyama, Gofuku, Toyama, Japan.,Institute of Agrobiological Sciences, NARO (National Agriculture and Food Research Organization), Tsukuba, Japan
| | - Ryutaro Suzuki
- Graduate School of Science and Engineering, University of Toyama, Gofuku, Toyama, Japan
| | - Ryouhei H Suzuki
- Graduate School of Science and Engineering, University of Toyama, Gofuku, Toyama, Japan
| | | | - Shuji Shigenobu
- NIBB Research Core Facilities, National Institute for Basic Biology, Okazaki, Japan
| | - Kiyoto Maekawa
- Faculty of Science, Academic Assembly, University of Toyama, Gofuku, Toyama, Japan
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da Silva LHB, Teixeira JAA, Laranjo LT, Costa-Leonardo AM, Vargo EL, Haifig I. Post-embryonic development of the female reproductive system of the Neotropical termite Silvestritermes euamignathus (Isoptera: Termitidae: Syntermitinae). ARTHROPOD STRUCTURE & DEVELOPMENT 2022; 71:101215. [PMID: 36279589 DOI: 10.1016/j.asd.2022.101215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/30/2022] [Accepted: 10/01/2022] [Indexed: 06/16/2023]
Abstract
In termites, the maturation of the female reproductive system is progressive following post-embryonic development. In Silvestritermes euamignathus, the imaginal line is characterized by five nymphal instars that develop into the imago, but it can deviate in some instars to neotenic reproductives. In order to understand the rate of development of the female reproductive system throughout post-embryonic development, we analyzed the morphology of the reproductive system of nymphs, characterizing the stage of development and comparing it with neotenics and primary queens. We also followed embryonic development and compared eggs from neotenics and primary queens from incipient and mature colonies. Our results showed that gonadal development follows the post-embryonic instars, and previtellogenic oocytes are present in third-instar nymphs and are retained for the next two successive nymphal instars. The full maturation of the ovaries with vitellogenic oocytes requires molting to either imagos or neotenics. Eggs from neotenics follow the same embryonic development and each stage presents similar volume when compared to those of mature primary queens. Eggs of primary queens from incipient colonies are greater in volume than those of mature primary queens and of neotenics, suggesting an investment in egg quality rather than quantity during colony foundation.
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Affiliation(s)
- Luiza Helena Bueno da Silva
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC - UFABC, Bloco Delta, Sala 241, Rua Arcturus, 03, Jardim Antares, São Bernardo Do Campo, SP, 09606-070, Brazil.
| | - Julia Ayumi Ando Teixeira
- Laboratório de Cupins, Departamento de Biologia Geral e Aplicada, Instituto de Biociências, UNESP - Univ Estadual Paulista, Av. 24A, 1515, 13506-900, Rio Claro, SP, Brazil.
| | - Lara Teixeira Laranjo
- Laboratório de Cupins, Departamento de Biologia Geral e Aplicada, Instituto de Biociências, UNESP - Univ Estadual Paulista, Av. 24A, 1515, 13506-900, Rio Claro, SP, Brazil.
| | - Ana Maria Costa-Leonardo
- Laboratório de Cupins, Departamento de Biologia Geral e Aplicada, Instituto de Biociências, UNESP - Univ Estadual Paulista, Av. 24A, 1515, 13506-900, Rio Claro, SP, Brazil.
| | - Edward L Vargo
- Department of Entomology, Texas A&M University, College Station, TX, 77843, USA.
| | - Ives Haifig
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC - UFABC, Bloco Delta, Sala 241, Rua Arcturus, 03, Jardim Antares, São Bernardo Do Campo, SP, 09606-070, Brazil.
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Comparison of gene expression profiles among caste differentiations in the termite Reticulitermes speratus. Sci Rep 2022; 12:11947. [PMID: 35831400 PMCID: PMC9279399 DOI: 10.1038/s41598-022-15984-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 07/04/2022] [Indexed: 11/08/2022] Open
Abstract
Termite castes express specialized phenotypes for their own tasks and are a good example of insect polyphenism. To understand the comprehensive gene expression profiles during caste differentiation, RNA-seq analysis based on the genome data was performed during the worker, presoldier, and nymphoid molts in Reticulitermes speratus. In this species, artificial induction methods for each molt have already been established, and the time scale has been clarified. Three different periods (before the gut purge (GP), during the GP, and after the molt) were discriminated in each molt, and two body parts (head and other body regions) were separately sampled. The results revealed that many differentially expressed genes (head: 2884, body: 2579) were identified in each molt. Based on the independent real-time quantitative PCR analysis, we confirmed the different expression patterns of seven out of eight genes in the presoldier molt. Based on the GO and KEGG enrichment analyses, the expressions of genes related to juvenile hormone titer changes (e.g., JH acid methyltransferase), nutrition status (e.g., Acyl-CoA Delta desaturase), and cell proliferation (e.g., insulin receptor), were shown to specifically fluctuate in each molt. These differences may have a crucial impact on caste differentiation. These data are important resources for future termite sociogenomics.
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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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Milacek M, Bittova L, Tumova S, Luksan O, Hanus R, Kyjakova P, Machara A, Marek A, Jindra M. Binding of de novo synthesized radiolabeled juvenile hormone (JH III) by JH receptors from the Cuban subterranean termite Prorhinotermes simplex and the German cockroach Blattella germanica. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 139:103671. [PMID: 34656795 DOI: 10.1016/j.ibmb.2021.103671] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 10/11/2021] [Accepted: 10/11/2021] [Indexed: 06/13/2023]
Abstract
Juvenile hormone (JH) controls insect reproduction and development through an intracellular receptor complex comprising two bHLH-PAS proteins, the JH-binding Methoprene-tolerant (Met) and its partner Taiman (Tai). Many hemimetabolous insects including cockroaches strictly depend on JH for stimulation of vitellogenesis. In termites, the eusocial hemimetabolans, JH also regulates the development of caste polyphenism. Studies addressing the agonist ligand binding to recombinant JH receptors currently include three species belonging to two holometabolous insect orders, but none that would represent any of the hemimetabolous orders. Here, we examined JH receptors in two representatives of Blattodea, the cockroach Blattella germanica and the termite Prorhinotermes simplex. To test the JH-binding capacity of Met proteins from these species, we performed chemical synthesis and tritium labeling of the natural blattodean JH homolog, JH III. Our improved protocol increased the yield and specific activity of [10-3H]JH III relative to formerly available preparations. Met proteins from both species specifically bound [3H]JH III with high affinity, whereas Met variants mutated at a critical position within the ligand-binding domain were incapable of such binding. Furthermore, JH III and the synthetic JH mimic fenoxycarb stimulated dimerization between Met and Tai components of the respective JH receptors of both species. These data present primary evidence for agonist binding by JH receptors in any hemimetabolous species and provide a molecular basis for JH action in cockroaches and termites.
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Affiliation(s)
- Matej Milacek
- Biology Center of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, 370 05, Czech Republic; Department of Molecular Biology and Genetics, University of South Bohemia, Ceske Budejovice, 370 05, Czech Republic
| | - Lenka Bittova
- Biology Center of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, 370 05, Czech Republic
| | - Sarka Tumova
- Biology Center of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, 370 05, Czech Republic
| | - Ondrej Luksan
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, 166 10, Czech Republic
| | - Robert Hanus
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, 166 10, Czech Republic
| | - Pavlina Kyjakova
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, 166 10, Czech Republic
| | - Ales Machara
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, 166 10, Czech Republic
| | - Ales Marek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, 166 10, Czech Republic.
| | - Marek Jindra
- Biology Center of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, 370 05, Czech Republic; Department of Molecular Biology and Genetics, University of South Bohemia, Ceske Budejovice, 370 05, Czech Republic.
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12
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Role of Endocrine System in the Regulation of Female Insect Reproduction. BIOLOGY 2021; 10:biology10070614. [PMID: 34356469 PMCID: PMC8301000 DOI: 10.3390/biology10070614] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 06/26/2021] [Accepted: 06/30/2021] [Indexed: 12/23/2022]
Abstract
The proper synthesis and functioning of ecdysteroids and juvenile hormones (JHs) are very important for the regulation of vitellogenesis and oogenesis. However, their role and function contrast among different orders, and even in the same insect order. For example, the JH is the main hormone that regulates vitellogenesis in hemimetabolous insect orders, which include Orthoptera, Blattodea, and Hemiptera, while ecdysteroids regulate the vitellogenesis among the insect orders of Diptera, some Hymenoptera and Lepidoptera. These endocrine hormones also regulate each other. Even at some specific stage of insect life, they positively regulate each other, while at other stages of insect life, they negatively control each other. Such positive and negative interaction of 20-hydroxyecdysone (20E) and JH is also discussed in this review article to better understand the role of these hormones in regulating the reproduction. Therefore, the purpose of the present review is to deeply understand the complex interaction of endocrine hormones with each other and with the insulin signaling pathway. The role of microbiomes in the regulation of the insect endocrine system is also reviewed, as the endocrine hormones are significantly affected by the compounds produced by the microbiota.
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Nozaki T, Matsuura K. Oocyte resorption in termite queens: Seasonal dynamics and controlling factors. JOURNAL OF INSECT PHYSIOLOGY 2021; 131:104242. [PMID: 33845091 DOI: 10.1016/j.jinsphys.2021.104242] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/17/2021] [Accepted: 04/05/2021] [Indexed: 06/12/2023]
Abstract
Female insects can resorb their oocytes that could not be oviposited. Oocyte resorption is proposed to be an adaptive mechanism to optimize fitness in hostile environments, recouping resources that might otherwise be lost. Social insects have developed reproductive division of labor, wherein a small number of queens are devoted to egg production. Matured queens are highly specialized in reproduction and are largely dependent on nestmate workers for their nourishment. Therefore, oocyte resorption in the queens should be influenced by social factors such as the amount of available workforce, as well as external and abiotic factors. In this study, we investigated the seasonal dynamics and regulation factors of oocyte resorption in actively reproducing termite queens. We continuously collected the field-nests of the subterranean termite Reticulitermes speratus and demonstrated that queens frequently resorbed their oocytes in late summer, even though it is one of the most productive seasons in this species. On the other hand, our laboratory experiment showed that oocyte resorption itself was strongly induced regardless of the season. We also found that the rate of oocyte resorption was influenced by colony size (the number of attending workers). These results suggest that termite queens seasonally resorb their oocytes, yet oocyte resorption itself is regulated by social factors rather than by seasonal factors. Our study provides a unique insight into the regulation of reproduction in social insects.
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Affiliation(s)
- Tomonari Nozaki
- Laboratory of Insect Ecology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan; Laboratory of Evolutionary Genomics, National Institute for Basic Biology, Okazaki, Japan.
| | - Kenji Matsuura
- Laboratory of Insect Ecology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
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14
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Oguchi K, Maekawa K, Miura T. Regulatory Mechanisms Underlying the Differentiation of Neotenic Reproductives in Termites: Partial Release From Arrested Development. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.635552] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Eusocial insects exhibit reproductive division of labor, in which only a part of colony members differentiates into reproductives. In termite colonies, the division of labors is performed among multiple types of individuals (i.e., castes), such as reproductives, workers, and soldiers to organize their society. Caste differentiation occurs according to extrinsic factors, such as social interactions, leading to developmental modifications during postembryonic development, and consequently, the caste ratio in a colony is appropriately coordinated. In particular, when the current reproductives die or become senescent, some immature individuals molt into supplementary reproductives, also known as “neotenics,” that take over the reproductive task in their natal colony. Neotenics exhibit variety of larval features, such as winglessness, and thus, immature individuals are suggested to differentiate by a partial release from arrested development, particularly in the reproductive organs. These neotenic features, which have long been assumed to develop via heterochronic regulation, provide us opportunities to understand the developmental mechanisms and evolutionary origin of the novel caste. This article overviews the accumulated data on the physiological and developmental mechanisms that regulate the neotenic differentiation in termites. Furthermore, the evolutionary trajectories leading to neotenic differentiation are discussed, namely the acquisition of a regulatory mechanism that enable the partial release from a developmentally arrested state.
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15
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Vea IM, Minakuchi C. Atypical insects: molecular mechanisms of unusual life history strategies. CURRENT OPINION IN INSECT SCIENCE 2021; 43:46-53. [PMID: 33065338 DOI: 10.1016/j.cois.2020.09.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 09/23/2020] [Accepted: 09/29/2020] [Indexed: 06/11/2023]
Abstract
Metamorphosis undeniably shaped the evolutionary success of winged insects. So far, what we know about the hormonal regulation and molecular mechanisms controlling insect metamorphosis lies on the understanding of complete and incomplete metamorphosis. Rarer types of metamorphosis are overlooked, yet they could provide important insights as they represent deviations in life history strategies that are associated with unique ecological traits. The molecular mechanisms of these atypical metamorphoses are still poorly understood. With the rise of next-generation sequencing, and increasing interest in emerging organismal systems, it is now possible to start exploring the molecular mechanisms underlying atypical metamorphoses in insects. By focusing on neometaboly and paedomorphosis, we discuss how exploring their molecular mechanisms can complete our understanding on the evolution of insects and impact applied research areas. Continued decrease in next-generation sequencing costs and progress in genome editing will help decipher the proximate mechanisms of unusual life history strategies in insects.
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Affiliation(s)
- Isabelle M Vea
- University of Illinois at Chicago, Department of Biological Sciences, Chicago, IL, USA
| | - Chieka Minakuchi
- Nagoya University, Graduate School of Bio-agricultural Sciences, Nagoya, Japan
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16
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Scharf ME, Peterson BF. A Century of Synergy in Termite Symbiosis Research: Linking the Past with New Genomic Insights. ANNUAL REVIEW OF ENTOMOLOGY 2021; 66:23-43. [PMID: 33417825 DOI: 10.1146/annurev-ento-022420-074746] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Termites have long been studied for their symbiotic associations with gut microbes. In the late nineteenth century, this relationship was poorly understood and captured the interest of parasitologists such as Joseph Leidy; this research led to that of twentieth-century biologists and entomologists including Cleveland, Hungate, Trager, and Lüscher. Early insights came via microscopy, organismal, and defaunation studies, which led to descriptions of microbes present, descriptions of the roles of symbionts in lignocellulose digestion, and early insights into energy gas utilization by the host termite. Focus then progressed to culture-dependent microbiology and biochemical studies of host-symbiont complementarity, which revealed specific microhabitat requirements for symbionts and noncellulosic mechanisms of symbiosis (e.g., N2 fixation). Today, knowledge on termite symbiosis has accrued exponentially thanks to omic technologies that reveal symbiont identities, functions, and interdependence, as well as intricacies of host-symbiont complementarity. Moving forward, the merging of classical twentieth-century approaches with evolving omic tools should provide even deeper insights into host-symbiont interplay.
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Affiliation(s)
- Michael E Scharf
- Department of Entomology, Purdue University, West Lafayette, Indiana 47907, USA;
| | - Brittany F Peterson
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, Illinois 62026, USA;
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17
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Gijbels M, Schellens S, Schellekens T, Bruyninckx E, Marchal E, Vanden Broeck J. Precocious Downregulation of Krüppel-Homolog 1 in the Migratory Locust, Locusta migratoria, Gives Rise to An Adultoid Phenotype with Accelerated Ovarian Development but Disturbed Mating and Oviposition. Int J Mol Sci 2020; 21:E6058. [PMID: 32842716 PMCID: PMC7503607 DOI: 10.3390/ijms21176058] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 08/18/2020] [Accepted: 08/20/2020] [Indexed: 01/29/2023] Open
Abstract
Krüppel-homolog 1 (Kr-h1) is a zinc finger transcription factor maintaining the status quo in immature insect stages and promoting reproduction in adult insects through the transduction of the Juvenile Hormone (JH) signal. Knockdown studies have shown that precocious silencing of Kr-h1 in the immature stages results in the premature development of adult features. However, the molecular characteristics and reproductive potential of these premature adult insect stages are still poorly understood. Here we report on an adult-like or 'adultoid' phenotype of the migratory locust, Locusta migratoria, obtained after a premature metamorphosis induced by the silencing of LmKr-h1 in the penultimate instar. The freshly molted adultoid shows precocious development of adult features, corresponding with increased transcript levels of the adult specifier gene LmE93. Furthermore, accelerated ovarian maturation and vitellogenesis were observed in female adultoids, coinciding with elevated expression of LmCYP15A1 in corpora allata (CA) and LmKr-h1 and vitellogenin genes (LmVg) in fat body, whereas LmE93 and Methoprene-tolerant (LmMet) transcript levels decreased in fat body. In adultoid ovaries, expression of the Halloween genes, Spook (LmSpo) and Phantom (LmPhm), was elevated as well. In addition, the processes of mating and oviposition were severely disturbed in these females. L. migratoria is a well-known, swarm-forming pest insect that can destroy crops and harvests in some of the world's poorest countries. As such, a better understanding of factors that are capable of significantly reducing the reproductive potential of this pest may be of crucial importance for the development of novel locust control strategies.
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Affiliation(s)
- Marijke Gijbels
- Research Group of Molecular Developmental Physiology and Signal Transduction, KU Leuven, Zoological Institute, Naamsestraat 59 box 2465, 3000 Leuven, Belgium; (M.G.); (S.S.); (T.S.); (E.B.)
| | - Sam Schellens
- Research Group of Molecular Developmental Physiology and Signal Transduction, KU Leuven, Zoological Institute, Naamsestraat 59 box 2465, 3000 Leuven, Belgium; (M.G.); (S.S.); (T.S.); (E.B.)
| | - Tine Schellekens
- Research Group of Molecular Developmental Physiology and Signal Transduction, KU Leuven, Zoological Institute, Naamsestraat 59 box 2465, 3000 Leuven, Belgium; (M.G.); (S.S.); (T.S.); (E.B.)
| | - Evert Bruyninckx
- Research Group of Molecular Developmental Physiology and Signal Transduction, KU Leuven, Zoological Institute, Naamsestraat 59 box 2465, 3000 Leuven, Belgium; (M.G.); (S.S.); (T.S.); (E.B.)
| | - Elisabeth Marchal
- Research Group of Molecular Developmental Physiology and Signal Transduction, KU Leuven, Zoological Institute, Naamsestraat 59 box 2465, 3000 Leuven, Belgium; (M.G.); (S.S.); (T.S.); (E.B.)
- Life Science Technologies, Imec, Kapeldreef 75, B- 3001 Leuven, Belgium
| | - Jozef Vanden Broeck
- Research Group of Molecular Developmental Physiology and Signal Transduction, KU Leuven, Zoological Institute, Naamsestraat 59 box 2465, 3000 Leuven, Belgium; (M.G.); (S.S.); (T.S.); (E.B.)
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18
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Oguchi K, Sugime Y, Shimoji H, Hayashi Y, Miura T. Male neotenic reproductives accelerate additional differentiation of female reproductives by lowering JH titer in termites. Sci Rep 2020; 10:9435. [PMID: 32523105 PMCID: PMC7286905 DOI: 10.1038/s41598-020-66403-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 05/19/2020] [Indexed: 12/02/2022] Open
Abstract
Eusocial insects exhibit reproductive division of labor, in which only a fraction of colony members differentiate into reproductives. In termites, reproductives of both sexes are present in a colony and constantly engaged in reproduction. It has been suggested that the sex ratio of reproductives is maintained by social interactions. The presence of reproductives is known to inhibit the additional differentiation of same-sex reproductives, while it promotes the differentiation of opposite-sex reproductives. In this study, using the damp-wood termite Hodotermopsis sjostedti, physiological effects of male/female reproductives on the differentiation of supplementary reproductives (neotenics) were examined. The results showed that the only male-neotenic condition, i.e., the presence of male neotenics in the absence of female neotenics, accelerated the neotenic differentiation from female workers (i.e., pseudergates). Under this condition, the rise of juvenile hormone (JH) titer was repressed in females, and the application of a JH analog inhibited the female neotenic differentiation, indicating that the low JH titer leads to rapid differentiation. Thus, the only male-neotenic condition that actively promotes reproductive differentiation by manipulating physiological condition of females is suggested to be a mechanism underlying sexual asymmetry in reproductive function, which may lead the female-biased sex allocation of reproductives.
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Affiliation(s)
- Kohei Oguchi
- Misaki Marine Biological Station, School of Science, The University of Tokyo, Misaki, Miura, Kanagawa, 238-0225, Japan
| | - Yasuhiro Sugime
- Laboratory of Ecological Genetics, Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan
| | - Hiroyuki Shimoji
- Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, 669-1337, Japan
| | - Yoshinobu Hayashi
- Department of Biology, Keio University, Yokohama, Kanagawa, 223-8521, Japan
| | - Toru Miura
- Misaki Marine Biological Station, School of Science, The University of Tokyo, Misaki, Miura, Kanagawa, 238-0225, Japan.
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19
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Miura T, Maekawa K. The making of the defensive caste: Physiology, development, and evolution of the soldier differentiation in termites. Evol Dev 2020; 22:425-437. [PMID: 32291940 DOI: 10.1111/ede.12335] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 02/11/2020] [Accepted: 03/08/2020] [Indexed: 12/29/2022]
Abstract
Termites (Blattodea, Termitoidea, or Isoptera) constitute one of the major lineages of eusocial insects. In termite societies, multiple types of functional individuals, that is, castes, perform divisions of labors to coordinate social behaviors. Among other castes, the soldier caste is distinctive since it is sterile and exclusively specialized into defensive behavior with largely modified morphological features. Therefore, many of the previous studies have been focused on soldiers, in terms of ecology, behavior, and evolution as well as developmental and physiological mechanisms. This article overviews the accumulation of studies especially focusing on the developmental and physiological mechanisms underlying the soldier differentiation in termites. Furthermore, the evolutionary trajectories that have led the acquisition of soldier caste and have diversified the soldier characteristics in association with the social evolution are discussed.
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Affiliation(s)
- Toru Miura
- Department of Biological Sciences, Misaki Marine Biological Station, School of Science, The University of Tokyo, Japan
| | - Kiyoto Maekawa
- Department of Biology, Faculty of Science, Academic Assembly, University of Toyama, Toyama, Japan
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20
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Suzuki R, Yaguchi H, Maekawa K. Histone modifying genes are involved in the molting period during soldier differentiation in Zootermopsis nevadensis. JOURNAL OF INSECT PHYSIOLOGY 2019; 117:103892. [PMID: 31170409 DOI: 10.1016/j.jinsphys.2019.103892] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 05/05/2019] [Accepted: 06/01/2019] [Indexed: 06/09/2023]
Abstract
Caste differentiation in eusocial insects is an outstanding example of phenotypic plasticity. Recent studies indicate that epigenetic regulation, including DNA methylation and histone modification, play a role in the morphological and behavioral polyphenism observed in the caste differentiation of hymenopteran insects. The role of epigenetic regulation in termite caste differentiation, however, is still obscure. In this study, we performed a functional analysis of epigenetic-related genes during soldier differentiation in Zootermopsis nevadensis, for which the entire genome sequence is available. In an incipient colony of this species, the oldest 3rd instar larva (No. 1 larva) always differentiates into a presoldier (intermediate stage of soldier), and the next-oldest 3rd instar larva (No. 2 larva) molts into a 4th instar (which functions as a worker). First, we detected seven epigenetic-related genes with significantly increased expression levels in the soldier-destined No. 1 larvae using RNA-seq data. Second, RNA interference (RNAi) of these seven genes was performed in the No. 1 larvae. RNAi of three histone modifying genes extended the presoldier molting period. Furthermore, these RNAi treatments reduced the expression levels of genes involved in juvenile hormone (JH) synthesis, binding and signaling. These results indicate that epigenetic-related genes do not directly affect termite soldier differentiation; nonetheless, some histone modifying genes have an effect on molting periods, possibly due to the regulation of JH action during soldier differentiation.
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Affiliation(s)
- Ryutaro Suzuki
- Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
| | - Hajime Yaguchi
- Graduate School of Science and Engineering, University of Toyama, Toyama, Japan; Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Japan
| | - Kiyoto Maekawa
- Graduate School of Science and Engineering, University of Toyama, Toyama, Japan.
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21
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Gijbels M, Lenaerts C, Vanden Broeck J, Marchal E. Juvenile Hormone receptor Met is essential for ovarian maturation in the Desert Locust, Schistocerca gregaria. Sci Rep 2019; 9:10797. [PMID: 31346226 PMCID: PMC6658565 DOI: 10.1038/s41598-019-47253-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 07/12/2019] [Indexed: 01/23/2023] Open
Abstract
Juvenile hormones (JH) are key endocrine regulators produced by the corpora allata (CA) of insects. Together with ecdysteroids, as well as nutritional cues, JH coordinates different aspects of insect postembryonic development and reproduction. The function of the recently characterized JH receptor, Methoprene-tolerant (Met), appears to be conserved in different processes regulated by JH. However, its functional interactions with other hormonal signalling pathways seem highly dependent on the feeding habits and on the developmental and reproductive strategies employed by the insect species investigated. Here we report on the effects of RNA interference (RNAi) mediated SgMet knockdown during the first gonadotrophic cycle in female desert locusts (Schistocerca gregaria). This voracious, phytophagous pest species can form migrating swarms that devastate field crops and harvests in several of the world’s poorest countries. A better knowledge of the JH signalling pathway may contribute to the development of novel, more target-specific insecticides to combat this very harmful swarming pest. Using RNAi, we show that the JH receptor Met is essential for ovarian maturation, vitellogenesis and associated ecdysteroid biosynthesis in adult female S. gregaria. Interestingly, knockdown of SgMet also resulted in a significant decrease of insulin-related peptide (SgIRP) and increase of neuroparsin (SgNP) 3 and 4 transcript levels in the fat body, illustrating the existence of an intricate regulatory interplay between different hormonal factors. In addition, SgMet knockdown in females resulted in delayed display of copulation behaviour with virgin males, when compared with dsGFP injected control animals. Moreover, we observed an incapacity of adult dsSgMet injected female locusts to oviposit during the time of the experimental setup. As such, SgMet is an essential gene playing crucial roles in the endocrine communication necessary for successful reproduction of the desert locust.
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Affiliation(s)
- Marijke Gijbels
- Research group of Molecular Developmental Physiology and Signal Transduction, KU Leuven, Zoological Institute, Naamsestraat 59 box 2465, 3000, Leuven, Belgium
| | - Cynthia Lenaerts
- Research group of Molecular Developmental Physiology and Signal Transduction, KU Leuven, Zoological Institute, Naamsestraat 59 box 2465, 3000, Leuven, Belgium
| | - Jozef Vanden Broeck
- Research group of Molecular Developmental Physiology and Signal Transduction, KU Leuven, Zoological Institute, Naamsestraat 59 box 2465, 3000, Leuven, Belgium.
| | - Elisabeth Marchal
- Research group of Molecular Developmental Physiology and Signal Transduction, KU Leuven, Zoological Institute, Naamsestraat 59 box 2465, 3000, Leuven, Belgium. .,Imec, Kapeldreef 75, B- 3001, Leuven, Belgium.
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22
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Santos CG, Humann FC, Hartfelder K. Juvenile hormone signaling in insect oogenesis. CURRENT OPINION IN INSECT SCIENCE 2019; 31:43-48. [PMID: 31109672 DOI: 10.1016/j.cois.2018.07.010] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 07/15/2018] [Indexed: 06/09/2023]
Abstract
Juvenile hormone (JH) plays a crucial role in insect reproduction, but its molecular mode of action only became clear within the last decade. We here review recent findings revealing the intricate crosstalk between JH and ecdysone signaling with nutrient sensing pathways in Drosophila melanogaster, Aedes aegypti, Tribolium castaneum and Locusta migratoria. The finding for a critical role of ecdysis triggering hormone (ETH) in both molting and ooogenesis now also highlights the importance of an integrated view of development and reproduction. Furthermore, insights from non-model insects, especially so social Hymenoptera and termites, where JH function gradually becomes decoupled from reproduction and plays a role in division of labor, emphasize the need to consider life cycle and life history strategies when studying insect reproductive physiology.
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Affiliation(s)
- Carolina Gonçalves Santos
- Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
| | | | - Klaus Hartfelder
- Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
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23
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Vea IM, Tanaka S, Tsuji T, Shiotsuki T, Jouraku A, Minakuchi C. E93 expression and links to the juvenile hormone in hemipteran mealybugs with insights on female neoteny. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 104:65-72. [PMID: 30503224 DOI: 10.1016/j.ibmb.2018.11.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 11/28/2018] [Accepted: 11/28/2018] [Indexed: 06/09/2023]
Abstract
Insect metamorphosis produces reproductive adults and is commonly accompanied with the direct or indirect development of wings. In some winged insects, the imago is altered by life history changes. For instance, in scale insects and mealybugs, reproductive females retain juvenile features and are wingless. The transcription factor E93 triggers metamorphosis and plays in concert with the juvenile hormone pathway to guarantee the successful transition from juvenile to adult. We previously provided evidence of an atypical down-regulation of the juvenile hormone pathway during female development in the Japanese mealybug. Here, we further investigate how E93 is involved in the production of neotenic wingless females, by identifying its isoforms, assessing their expression patterns and evaluating the effect of exogenous juvenile hormone mimic treatment on E93. This study identifies three E93 isoforms on the 5' end, based on Japanese mealybug cDNA and shows that female development occurs with the near absence of E93 transcripts, as opposed to male metamorphosis. Additionally, while male development is typically affected by exogenous juvenile hormone mimic treatments, females seem to remain insensitive to the treatment, and up-regulation of the juvenile hormone signaling is not observed. Furthermore, juvenile hormone mimic treatment on female nymphs did not have an obvious effect on E93 transcription, while treatment on male prepupae resulted in depleted E93 transcripts. In this study, we emphasize the importance in examining atypical cases of metamorphosis as complementary systems to provide a better understanding on the molecular mechanisms underlying insect metamorphosis. For instance, the factors regulating the expression of E93 are largely unclear. Investigating the regulatory mechanism of E93 transcription could provide clues towards identifying the factors that induce or suppress E93 transcription, in turn triggering male adult development or female neoteny.
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Affiliation(s)
- Isabelle Mifom Vea
- Nagoya University, Graduate School of Bioagricultural Sciences, Nagoya, Japan; University of Edinburgh, Institute of Evolutionary Biology, Edinburgh, UK.
| | - Sayumi Tanaka
- Nagoya University, Graduate School of Bioagricultural Sciences, Nagoya, Japan
| | - Tomohiro Tsuji
- Nagoya University, Graduate School of Bioagricultural Sciences, Nagoya, Japan
| | - Takahiro Shiotsuki
- Institute of Agrobiological Sciences, National Institute of Agriculture and Food Research Organization, Tsukuba, Japan; Shimane University, Faculty of Life and Environmental Science, Matsue, Japan
| | - Akiya Jouraku
- Institute of Agrobiological Sciences, National Institute of Agriculture and Food Research Organization, Tsukuba, Japan
| | - Chieka Minakuchi
- Nagoya University, Graduate School of Bioagricultural Sciences, Nagoya, Japan
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24
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Zhen C, Yang H, Luo S, Huang J, Wu J. Broad-complex Z3 contributes to the ecdysone-mediated transcriptional regulation of the vitellogenin gene in Bombus lantschouensis. PLoS One 2018; 13:e0207275. [PMID: 30440013 PMCID: PMC6237364 DOI: 10.1371/journal.pone.0207275] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 10/29/2018] [Indexed: 01/03/2023] Open
Abstract
During reproduction, vitellogenin (Vg), as an egg yolk precursor, is critical in sexually mature females of oviparous species including some insects. The transcription of Vg is usually mediated by hormones such as juvenile hormone (JH), ecdysteroids and some neuropeptides. In this study, the structure of the Vg gene from the bumblebee Bombus lantschouensis, (BlVg) was determined by sequencing and assembly. BlVg was found to be expressed at higher levels in reproductive queens than in virgins by quantitative real-time PCR analysis. Tissue-specific expression analysis showed that BlVg was expressed at the highest levels in the fat bodies of both virgin and reproductive queens. Prediction of the BlVg promoter revealed the presence of ecdysteroid-responsive cis-regulatory elements (CREs) containing one Broad-Complex zinc-finger isoform 3 (BR-C Z3), and one ecdysone-induced protein 74A (E74A). In addition, luciferase reporter expression, driven by the 5' -regulatory region of the BlVg gene, from -1517 bp to +895 bp downstream of the start codon, was induced by treatment with 20-hydroxyecdysone (20-E). Moreover, the luciferase activity of the BlVg promoter was elevated by only BlBrC-Z3 when Sf9 cells were cotransfected with four BlBrC isoforms respectively. BlVg promoter-mediated luciferase activation was significantly reduced when the putative BrC-Z3 CRE in the promoter was mutated. In summary, this report describes the first study of vitellogenin gene regulation at the transcriptional level in bumblebees and demonstrates that the ecdysone-induced transcription of the BlVg gene is mediated by the binding of BlBrC-Z3 to the BrC-Z3 CRE in the BlVg promoter in bumblebees.
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Affiliation(s)
- Congai Zhen
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
| | - Huipeng Yang
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
| | - Shudong Luo
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
| | - Jiaxing Huang
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
- * E-mail: (JW); (JH)
| | - Jie Wu
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
- * E-mail: (JW); (JH)
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25
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Jongepier E, Kemena C, Lopez-Ezquerra A, Belles X, Bornberg-Bauer E, Korb J. Remodeling of the juvenile hormone pathway through caste-biased gene expression and positive selection along a gradient of termite eusociality. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2018; 330:296-304. [PMID: 29845724 DOI: 10.1002/jez.b.22805] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 04/25/2018] [Accepted: 05/03/2018] [Indexed: 11/10/2022]
Abstract
The evolution of division of labor between sterile and fertile individuals represents one of the major transitions in biological complexity. A fascinating gradient in eusociality evolved among the ancient hemimetabolous insects, ranging from noneusocial cockroaches through the primitively social lower termites-where workers retain the ability to reproduce-to the higher termites, characterized by lifetime commitment to worker sterility. Juvenile hormone (JH) is a prime candidate for the regulation of reproductive division of labor in termites, as it plays a key role in insect postembryonic development and reproduction. We compared the expression of JH pathway genes between workers and queens in two lower termites (Zootermopsis nevadensis and Cryptotermes secundus) and a higher termite (Macrotermes natalensis) to that of analogous nymphs and adult females of the noneusocial cockroach Blattella germanica. JH biosynthesis and metabolism genes ranged from reproductive female-biased expression in the cockroach to predominantly worker-biased expression in the lower termites. Remarkably, the expression profile of JH pathway genes sets the higher termite apart from the two lower termites, as well as the cockroach, indicating that JH signaling has undergone major changes in this eusocial termite. These changes go beyond mere shifts in gene expression between the different castes, as we find evidence for positive selection in several termite JH pathway genes. Thus, remodeling of the JH pathway may have played a major role in termite social evolution, representing a striking case of convergent molecular evolution between the termites and the distantly related social hymenoptera.
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Affiliation(s)
- Evelien Jongepier
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Carsten Kemena
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | | | - Xavier Belles
- Institut de Biologia Evolutiva, CSIC-University Pompeu Fabra, Barcelona, Spain
| | - Erich Bornberg-Bauer
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Judith Korb
- Evolutionary Biology & Ecology, University of Freiburg, Freiburg, Germany
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26
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Korb J. Chemical Fertility Signaling in Termites: Idiosyncrasies and Commonalities in Comparison with Ants. J Chem Ecol 2018; 44:818-826. [PMID: 29616376 DOI: 10.1007/s10886-018-0952-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 02/15/2018] [Accepted: 03/21/2018] [Indexed: 11/25/2022]
Abstract
Termites evolved eusociality independently from social Hymenoptera. As a common trait, reproductive monopoly is maintained through chemical communication. The queen (and in termites also a king) prevents workers from reproduction by conveying their reproductive status. In termites all soldiers are sterile, but workers' potential to reproduce differs between species. It ranges from totipotency in wood-dwelling lower termites where workers are a transient stage from which all other castes develop, to sterile workers in some higher termites. Intermediate are species in which workers can develop into replacement sexuals within the nest but not into winged sexuals. I summarize the patchy picture about fertility signaling that we currently have for termites, pointing also to potential conflicts over reproduction that differ from those in social Hymenoptera. Recent findings imply that, similar to many social Hymenoptera, wood-dwelling termites that live in confined nests use long-chain cuticular hydrocarbons (CHCs) as fertility signals. Yet other compounds are important as well, comprising proteinaceous secretions and especially volatiles. For a subterranean termite, two volatiles have been identified as primer pheromones that prevent reproductive differentiation of workers. It requires more data to test whether wood-dwelling termites use CHCs, while species with larger colonies and less confined nests use volatiles, or whether all species rely on multicomponent signals. Ultimately, we need more effort to model and test potential conflicts over reproduction between queens, kings and workers. Here results from social Hymenoptera cannot be transferred to termites as the latter are diploid and commonly inbred. This review illustrates promising future research avenues.
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Affiliation(s)
- Judith Korb
- Evolutionary Biology & Ecology, University of Freiburg, Hauptstrasse 1, D-79104, Freiburg, Germany.
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Korb J, Belles X. Juvenile hormone and hemimetabolan eusociality: a comparison of cockroaches with termites. CURRENT OPINION IN INSECT SCIENCE 2017; 22:109-116. [PMID: 28805632 DOI: 10.1016/j.cois.2017.06.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 05/17/2017] [Accepted: 06/09/2017] [Indexed: 06/07/2023]
Abstract
Termites are social Dictyoptera that evolved eusociality independently from social Hymenoptera. They are characterized by unique developmental plasticity that is the basis of caste differentiation and social organization. As developmental plasticity is a result of endocrine regulation, in order to understand the evolution of termite sociality it is helpful to compare the endocrine underpinning of development between termites and cockroaches. Nijhout and Wheeler (1982) proposed that varying JH titers determine caste differentiation in termites. Based on current results, we extend this model by adding the importance of social interactions. High JH titers in the presence of soldiers lead to regressive development (decrease in body size, apparent regression in development), while an absence of soldiers induces (pre-)soldier differentiation. On the opposite side, low JH titers in colonies headed by reproductives result in progressive molts toward adults, while an absence of reproductives induces development of replacement reproductives. In cockroaches, transcription factors involved in JH signaling, including the adult specifier E93 (the co-called MEKRE93 pathway) regulate the morphogenetic transition between the nymph and the adult. In termites, we speculate that castes might be determined by social effects playing a modulatory action of JH in the MEKRE93 pathway.
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Affiliation(s)
- Judith Korb
- Evolutionary Biology & Ecology, University of Freiburg, Hauptstrasse 1, D-79104 Freiburg, Germany.
| | - Xavier Belles
- Institute of Evolutionary Biology, CSIC-Universitat Pompeu Fabra, Passeig Marítim 37, 08003 Barcelona, Spain
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28
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Induction of a reproductive-specific cuticular hydrocarbon profile by a juvenile hormone analog in the termite Zootermopsis nevadensis. CHEMOECOLOGY 2016. [DOI: 10.1007/s00049-016-0219-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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29
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Liu W, Li Y, Zhu L, Zhu F, Lei CL, Wang XP. Juvenile hormone facilitates the antagonism between adult reproduction and diapause through the methoprene-tolerant gene in the female Colaphellus bowringi. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2016; 74:50-60. [PMID: 27180724 DOI: 10.1016/j.ibmb.2016.05.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Revised: 05/11/2016] [Accepted: 05/11/2016] [Indexed: 06/05/2023]
Abstract
In insects, the process whereby juvenile hormone (JH) regulates short-day (SD)-induced reproductive diapause has been previously investigated. However, we still do not understand the mechanism by which JH regulates long-day (LD)-induced reproductive diapause. In this study, we use a cabbage beetle, Colaphellus bowringi, which is a serious pest of cruciferous vegetables in Asia capable of entering reproductive diapause under LD conditions, as a model to test whether JH regulates female reproductive diapause similar to the mechanism of SD-induced diapause. Our results showed that the JH analog (JHA) methoprene significantly induced ovarian development but inhibited lipid accumulation of diapause-destined adults. Meanwhile, the transcripts of the vitellogenin (Vg) genes were upregulated, whereas the expression of the fat synthesis and stress tolerance genes were downregulated. RNA interference of the JH candidate receptor gene methoprene-tolerant (Met) blocked JH-induced ovarian development and Vg transcription, suggesting a positive regulatory function for JH-Met signaling in reproduction. Furthermore, under reproduction-inducing conditions, Met depletion promoted a diapause-like phenotype, including arrested ovarian development and increased lipid storage, and stimulated the expression of diapause-related genes involved in lipid synthesis and stress tolerance, suggesting JH-Met signaling plays an important role in the inhibition of diapause. Accordingly, our data indicate that JH acts through Met to facilitate development of the reproductive system by upregulating Vg expression while inhibiting diapause by suppressing lipid synthesis and stress tolerance in the cabbage beetle. Combined with previous studies in SD-induced reproductive diapause, we conclude that JH may regulate female reproductive diapause using a conserved Met-dependent pathway, regardless of the length of the photoperiod inducing diapause in insects.
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Affiliation(s)
- Wen Liu
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Yi Li
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Li Zhu
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Fen Zhu
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Chao-Liang Lei
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Xiao-Ping Wang
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China.
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Sillam-Dussès D, Hanus R, Poulsen M, Roy V, Favier M, Vasseur-Cognet M. The role of the glucose-sensing transcription factor carbohydrate-responsive element-binding protein pathway in termite queen fertility. Open Biol 2016; 6:160080. [PMID: 27249798 PMCID: PMC4892437 DOI: 10.1098/rsob.160080] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 04/25/2016] [Indexed: 12/04/2022] Open
Abstract
Termites are among the few animals that themselves can digest the most abundant organic polymer, cellulose, into glucose. In mice and Drosophila, glucose can activate genes via the transcription factor carbohydrate-responsive element-binding protein (ChREBP) to induce glucose utilization and de novo lipogenesis. Here, we identify a termite orthologue of ChREBP and its downstream lipogenic targets, including acetyl-CoA carboxylase and fatty acid synthase. We show that all of these genes, including ChREBP, are upregulated in mature queens compared with kings, sterile workers and soldiers in eight different termite species. ChREBP is expressed in several tissues, including ovaries and fat bodies, and increases in expression in totipotent workers during their differentiation into neotenic mature queens. We further show that ChREBP is regulated by a carbohydrate diet in termite queens. Suppression of the lipogenic pathway by a pharmacological agent in queens elicits the same behavioural alterations in sterile workers as observed in queenless colonies, supporting that the ChREBP pathway partakes in the biosynthesis of semiochemicals that convey the signal of the presence of a fertile queen. Our results highlight ChREBP as a likely key factor for the regulation and signalling of queen fertility.
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Affiliation(s)
- David Sillam-Dussès
- Laboratoire d'Ethologie Expérimentale et Comparée, Université Paris 13, EA4443, 93430 Villetaneuse, France UMR IRD 242, UPEC, CNRS 7618, UPMC 113, INRA 1392, PARIS 7 113, Institut d'Ecologie et des Sciences de l'Environnement de Paris, 93140 Bondy, France Sorbonne Paris Cité, Paris, France Sorbonne Universités, Paris, France
| | - Robert Hanus
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 16610 Prague, Czech Republic
| | - Michael Poulsen
- Centre for Social Evolution, Section for Ecology and Evolution, Department of Biology, University of Copenhagen, 2100 Copenhagen East, Denmark
| | - Virginie Roy
- UMR IRD 242, UPEC, CNRS 7618, UPMC 113, INRA 1392, PARIS 7 113, Institut d'Ecologie et des Sciences de l'Environnement de Paris, 93140 Bondy, France Sorbonne Paris Cité, Paris, France Sorbonne Universités, Paris, France
| | - Maryline Favier
- Institut National de la Santé et de la Recherche Médicale, Unité 1016, Institut Cochin, 75014 Paris, France
| | - Mireille Vasseur-Cognet
- UMR IRD 242, UPEC, CNRS 7618, UPMC 113, INRA 1392, PARIS 7 113, Institut d'Ecologie et des Sciences de l'Environnement de Paris, 93140 Bondy, France Sorbonne Paris Cité, Paris, France Sorbonne Universités, Paris, France Institut National de la Santé et de la Recherche Médicale, Unité 1016, Institut Cochin, 75014 Paris, France
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31
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Korb J. Genes Underlying Reproductive Division of Labor in Termites, with Comparisons to Social Hymenoptera. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00045] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Toga K, Hanmoto S, Suzuki R, Watanabe D, Miura T, Maekawa K. Sexual difference in juvenile-hormone titer in workers leads to sex-biased soldier differentiation in termites. JOURNAL OF INSECT PHYSIOLOGY 2016; 87:63-70. [PMID: 26868724 DOI: 10.1016/j.jinsphys.2016.02.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 02/01/2016] [Accepted: 02/06/2016] [Indexed: 06/05/2023]
Abstract
In termites, the soldier caste, with its specialized defensive morphology, is one of the most important characteristics for sociality. Most of the basal termite species have both male and female soldiers, and the soldier sex ratio is almost equal or only slightly biased. However, in the apical lineages (especially family Termitidae), there are many species that have soldiers with strongly biased sex ratio. Generally in termites, since high juvenile hormone (JH) titer is required for soldier differentiation from a worker via a presoldier stage, it was hypothesized that the biased soldier-sex ratio was caused by differences in JH sensitivity and/or JH titer between male and female workers. Therefore, we focused on the presoldier differentiation and the worker JH titer in species with only male soldiers (Nasutitermes takasagoensis) and with both male and female soldiers (Reticulitermes speratus) in natural conditions. In the former species, there are four types of workers; male minor, male medium, female medium and female major workers, and presoldiers differentiate from male minor workers. First, we tried to artificially induce presoldiers from male and female workers. In N. takasagoensis, the presoldier differentiation rate and mortality was significantly higher in male minor workers. Morphological analyses showed that both male and female induced presoldiers possessed normal soldier-specific morphologies. It was suggested that female workers, from which soldiers do not differentiate under natural conditions, also maintained the physiological and developmental potential for soldier differentiation. In R. speratus, however, no differences were observed in solder differentiation rate and mortality between male and female workers. Second, the JH titers of each sex/type of workers were quantified by high performance liquid chromatography-mass spectrometry in two different seasons (April and December). The results showed that, in N. takasagoensis, JH titer in male minor workers was consistently higher than those in other worker types. In R. speratus, in contrast, there were no significant differences in JH titers between male and female workers. These results suggested that, in N. takasagoensis, male minor workers maintain JH titers at a high level throughout a year, and this may cause the male-biased presoldier differentiation.
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Affiliation(s)
- Kouhei Toga
- Graduate School of Science and Engineering, University of Toyama, Toyama, Japan; Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Shutaro Hanmoto
- Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
| | - Ryutaro Suzuki
- Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
| | - Dai Watanabe
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan
| | - Toru Miura
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan
| | - Kiyoto Maekawa
- Graduate School of Science and Engineering, University of Toyama, Toyama, Japan.
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Masuoka Y, Yaguchi H, Suzuki R, Maekawa K. Knockdown of the juvenile hormone receptor gene inhibits soldier-specific morphogenesis in the damp-wood termite Zootermopsis nevadensis (Isoptera: Archotermopsidae). INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2015; 64:25-31. [PMID: 26188329 DOI: 10.1016/j.ibmb.2015.07.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 07/11/2015] [Accepted: 07/11/2015] [Indexed: 06/04/2023]
Abstract
The Methoprene-tolerant (Met) protein has been established as a juvenile hormone (JH) receptor. Knockdown of the Met gene caused precocious metamorphosis and suppression of ovarian development. However, the function of Met in caste development of social insects is unclear. In termites, JH acts as a central factor for caste development, especially for soldier differentiation, which involves two molts from workers via a presoldier stage. Increased JH titer in workers is needed for the presoldier molt, and the high JH titer is maintained throughout the presoldier period. Although presoldiers have the fundamental morphological features of soldiers, the nature of the cuticle is completely different from that of soldiers. We expected that JH signals via Met are involved in soldier-specific morphogenesis of the head and mandibles during soldier differentiation, especially in the presoldier period, in natural conditions. To test this hypothesis, we focused on soldier differentiation in an incipient colony of the damp-wood termite Zootermopsis nevadensis. Met homolog (ZnMet) expression in heads increased just after the presoldier molt. This high expression was reduced by ZnMet double stranded (dsRNA) injection before the presoldier molt. Although this treatment did not cause any morphological changes in presoldiers, it caused strong effects on soldiers, their mandibles being significantly shorter and head capsules smaller than those of control soldiers. Injection of ZnMet dsRNA throughout the presoldier stage did not affect the formation of soldier morphology, including cuticle formation. These results suggested that the rapid increase in ZnMet expression and subsequent activation of JH signaling just after the presoldier molt are needed for the formation of soldier-specific weapons. Therefore, besides its established role in insect metamorphosis, the JH receptor signaling also underlies soldier development in termites.
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Affiliation(s)
- Yudai Masuoka
- Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
| | - Hajime Yaguchi
- Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
| | - Ryutaro Suzuki
- Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
| | - Kiyoto Maekawa
- Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
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