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Hellemans S, Hanus R. Termite primary queen - ancestral, but highly specialized eusocial phenotype. CURRENT OPINION IN INSECT SCIENCE 2024; 61:101157. [PMID: 38142979 DOI: 10.1016/j.cois.2023.101157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/20/2023] [Accepted: 12/20/2023] [Indexed: 12/26/2023]
Abstract
Termite eusociality is accompanied by flagrant caste polyphenism manifested by the presence of several sterile (workers and soldiers) and reproductive (imaginal and neotenic kings and queens) caste phenotypes. Imaginal kings and queens are developmentally equivalent to adults of other hemimetabolous insects but display multiple adaptations inherent to their role of eusocial colony founders, such as long lifespan and high fecundity. Herein, we summarize the recent advances in understanding the biology of imaginal (primary) queens as emblematic examples of termite polyphenism acquired during social evolution. We focus on the control of queen development, on dynamics in physiology and fecundity during the queen's life, on new findings about queen fertility signaling, and on proximate mechanisms underlying queen longevity.
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Affiliation(s)
- Simon Hellemans
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan; Evolutionary Biology and Ecology, Université libre de Bruxelles, 50 avenue F.D. Roosevelt, 1050 Brussels, Belgium
| | - Robert Hanus
- Chemistry of Social Insects, Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 160 00 Prague, Czech Republic.
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Cressman A, Amsalem E. Impacts and mechanisms of CO2 narcosis in bumble bees: narcosis depends on dose, caste and mating status and is not induced by anoxia. J Exp Biol 2023; 226:286149. [PMID: 36541091 DOI: 10.1242/jeb.244746] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022]
Abstract
Carbon dioxide (CO2) is commonly used to immobilize insects and to induce reproduction in bees. However, despite its wide use and potential off-target impacts, its underlying mechanisms are not fully understood. Here, we used Bombus impatiens to examine whether CO2 impacts are mediated by anoxia and whether these mechanisms differ between female castes or following mating in queens. We examined the behavior, physiology and gene expression of workers, mated queens and virgin queens following exposure to anoxia, hypoxia, full and partial hypercapnia, and controls. Hypercapnia and anoxia caused immobilization, but only hypercapnia resulted in behavioral, physiological and molecular impacts in bees. Recovery from hypercapnia resulted in increased abdominal contractions and took longer in queens. Additionally, hypercapnia activated the ovaries of queens, but inhibited those of workers in a dose-dependent manner and caused a depletion of fat-body lipids in both castes. All responses to hypercapnia were weaker following mating in queens. Analysis of gene expression related to hypoxia and hypercapnia supported the physiological findings in queens, demonstrating that the overall impacts of CO2, excluding virgin queen ovaries, were unique and were not induced by anoxia. This study contributes to our understanding of the impacts and the mechanistic basis of CO2 narcosis in insects and its impacts on bee physiology. This article has an associated ECR Spotlight interview with Anna Cressman.
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Affiliation(s)
- Anna Cressman
- Department of Entomology, Center for Chemical Ecology, Center for Pollination Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Etya Amsalem
- Department of Entomology, Center for Chemical Ecology, Center for Pollination Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
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Treanore ED, Amsalem E. Examining the individual and additive effects of cold storage and CO 2 narcosis on queen survival and reproduction in bumble bees. JOURNAL OF INSECT PHYSIOLOGY 2022; 139:104394. [PMID: 35413337 DOI: 10.1016/j.jinsphys.2022.104394] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 04/06/2022] [Accepted: 04/07/2022] [Indexed: 06/14/2023]
Abstract
Diapause is a pre-programmed arrest of development allowing insects to survive in unfavorable environments. In adult insects, diapause termination is often followed by a reallocation of macronutrients and a transition to reproduction, and in some insects, this transition can be achieved using narcosis with CO2. However, whether CO2narcosis and diapause act in concert to affect reproduction remains unknown. Here, we investigated the separated and combined effects of diapause and CO2on female reproduction in queens of the common eastern bumble bee Bombus impatiens. Queens were treated with CO2 following a cold storage period (zero days, two weeks, two and four months) and were compared with untreated queens at the same timepoints for survival, colony initiation, egg-laying latency, and offspring production. We found that both CO2 and a period of at least two months in cold storage induced a transition to egg laying in gynes, and as expected, survival decreased with cold storage length. When CO2 and cold storage were combined, CO2narcosis positively affected egg laying in the earlier timepoints but its impact diminished following a longer cold storage. These data suggest that the impacts of CO2narcosis and cold storage are partially additive, and application of CO2 is effective only after a short cold storage. It further demonstrates that CO2 has complex effects on insect reproduction that are independent from diapause.
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Affiliation(s)
- Erin D Treanore
- Department of Entomology, Center for Chemical Ecology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA.
| | - Etya Amsalem
- Department of Entomology, Center for Chemical Ecology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
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He L, Chen IW, Zhang Z, Zheng W, Sayadi A, Wang L, Sang W, Ji R, Lei J, Arnqvist G, Lei C, Zhu-Salzman K. In silico promoter analysis and functional validation identify CmZFH, the co-regulator of hypoxia-responsive genes CmScylla and CmLPCAT. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2022; 140:103681. [PMID: 34800642 DOI: 10.1016/j.ibmb.2021.103681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 09/30/2021] [Accepted: 11/06/2021] [Indexed: 06/13/2023]
Abstract
Oxygen (O2) plays an essential role in aerobic organisms including terrestrial insects. Under hypoxic stress, the cowpea bruchid (Callosobruchus maculatus) ceases feeding and growth. However, larvae, particularly 4th instar larvae exhibit very high tolerance to hypoxia and can recover normal growth once brought to normoxia. To better understand the molecular mechanism that enables insects to cope with low O2 stress, we performed RNA-seq to distinguish hypoxia-responsive genes in midguts and subsequently identified potential common cis-elements in promoters of hypoxia-induced and -repressed genes, respectively. Selected elements were subjected to gel-shift and transient transfection assays to confirm their cis-regulatory function. Of these putative common cis-elements, AREB6 appeared to regulate the expression of CmLPCAT and CmScylla, two hypoxia-induced genes. CmZFH, the putative AREB6-binding protein, was hypoxia-inducible. Transient expression of CmZFH in Drosophila S2 cells activated CmLPCAT and CmScylla, and their induction was likely through interaction of CmZFH with AREB6. Binding to AREB6 was further confirmed by bacterially expressed CmZFH recombinant protein. Deletion analyses indicated that the N-terminal zinc-finger cluster of CmZFH was the key AREB6-binding domain. Through in silico and experimental exploration, we discovered novel transcriptional regulatory components associated with gene expression dynamics under hypoxia that facilitated insect survival.
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Affiliation(s)
- Li He
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China; Department of Entomology, Texas A&M University, College Station, TX, 77843, USA; Institute for Plant Genomics & Biotechnology, Texas A&M University, College Station, TX, 77843, USA
| | - Ivy W Chen
- Department of Entomology, Texas A&M University, College Station, TX, 77843, USA; Institute for Plant Genomics & Biotechnology, Texas A&M University, College Station, TX, 77843, USA
| | - Zan Zhang
- Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Academy of Agricultural Sciences, Southwest University, Chongqing, 400716, China
| | - Wenping Zheng
- Key Laboratory of Horticultural Plant Biology (MOE), Institute of Urban and Horticultural Entomology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Ahmed Sayadi
- Animal Ecology, Department of Ecology and Genetics, Uppsala University, Uppsala, 75236, Sweden
| | - Lei Wang
- Department of Entomology, Texas A&M University, College Station, TX, 77843, USA; Institute for Plant Genomics & Biotechnology, Texas A&M University, College Station, TX, 77843, USA
| | - Wen Sang
- Department of Entomology, Texas A&M University, College Station, TX, 77843, USA; Institute for Plant Genomics & Biotechnology, Texas A&M University, College Station, TX, 77843, USA
| | - Rui Ji
- Department of Entomology, Texas A&M University, College Station, TX, 77843, USA; Institute for Plant Genomics & Biotechnology, Texas A&M University, College Station, TX, 77843, USA
| | - Jiaxin Lei
- Department of Entomology, Texas A&M University, College Station, TX, 77843, USA; Institute for Plant Genomics & Biotechnology, Texas A&M University, College Station, TX, 77843, USA
| | - Göran Arnqvist
- Animal Ecology, Department of Ecology and Genetics, Uppsala University, Uppsala, 75236, Sweden
| | - Chaoliang Lei
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Keyan Zhu-Salzman
- Department of Entomology, Texas A&M University, College Station, TX, 77843, USA; Institute for Plant Genomics & Biotechnology, Texas A&M University, College Station, TX, 77843, USA.
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Tasaki E, Takata M, Matsuura K. Why and how do termite kings and queens live so long? Philos Trans R Soc Lond B Biol Sci 2021; 376:20190740. [PMID: 33678028 PMCID: PMC7938161 DOI: 10.1098/rstb.2019.0740] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2020] [Indexed: 12/23/2022] Open
Abstract
Lifespan varies greatly across the tree of life. Of the various explanations for this phenomenon, those that involve trade-offs between reproduction and longevity have gained considerable support. There is an important exception: social insect reproductives (queens and in termites, also kings) exhibit both high reproductive outputs and extraordinarily long lives. As both the ultimate and proximate mechanisms underlying the absence of the fecundity/longevity trade-off could shed light on the unexpected dynamics and molecular mechanisms of extended longevity, reproductives of social insects have attracted much attention in the field of ageing research. Here, we highlight current ecological and physiological studies on ageing and discuss the various possible evolutionary and molecular explanations of the extended lifespans of termite reproductives. We integrate these findings into a coherent framework revealing the evolution of longevity in these reproductives. Studies on termites may explain why and how ageing is shaped by natural selection. This article is part of the theme issue 'Ageing and sociality: why, when and how does sociality change ageing patterns?'
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Affiliation(s)
- Eisuke Tasaki
- Laboratory of Insect Ecology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Mamoru Takata
- Laboratory of Insect Ecology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Kenji Matsuura
- Laboratory of Insect Ecology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
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Transcriptomic evidence that insulin signalling pathway regulates the ageing of subterranean termite castes. Sci Rep 2020; 10:8187. [PMID: 32424344 PMCID: PMC7235038 DOI: 10.1038/s41598-020-64890-9] [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: 09/23/2019] [Accepted: 04/20/2020] [Indexed: 12/19/2022] Open
Abstract
Insulin is a protein hormone that controls the metabolism of sugar, fat and protein via signal transduction in cells, influencing growth and developmental processes such as reproduction and ageing. From nematodes to fruit flies, rodents and other animals, glucose signalling mechanisms are highly conserved. Reproductive termites (queens and kings) exhibit an extraordinarily long lifespan relative to non-reproductive individuals such as workers, despite being generated from the same genome, thus providing a unique model for the investigation of longevity. The key reason for this molecular mechanism, however, remains unclear. To clarify the molecular mechanism underlying this phenomenon, we sequenced the transcriptomes of the primary kings (PKs), primary queens (PQs), male (WMs) and female (WFs) workers of the lower subterranean termite Reticulitermes chinensis. We performed RNA sequencing and identified 33 insulin signalling pathway-related genes in R. chinensis. RT-qPCR analyses revealed that EIF4E and RPS6 genes were highly expressed in WMs and WFs workers, while mTOR expression was lower in PKs and PQs than in WMs and WFs. PQs and PKs exhibited lower expression of akt2-a than female workers. As the highly conserved insulin signalling pathway can significantly prolong the healthspan and lifespan, so we infer that the insulin signalling pathway regulates ageing in the subterranean termite R. chinensis. Further studies are recommended to reveal the biological function of insulin signalling pathway-related genes in the survival of termites to provide new insights into biomolecular homeostasis maintenance and its relationship to remarkable longevity.
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Tasaki E, Komagata Y, Inagaki T, Matsuura K. Reproduction deep inside wood: a low O 2 and high CO 2 environment promotes egg production by termite queens. Biol Lett 2020; 16:20200049. [PMID: 32264784 DOI: 10.1098/rsbl.2020.0049] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Extreme conditions are normal for animals living in harsh environments. These animals adapt to their habitats and can use difficult conditions by default. Organisms living in enclosed spaces, notably termites in decaying wood, experience low O2 and high CO2 gas conditions due to limited gas exchange and high insect density. Termite queens, in particular, reproduce in royal chambers deep inside the wood, wherein tens of thousands of individuals engage in social labour. Here, we demonstrate that royal chambers in termite nests have low O2 and high CO2 gas concentrations, which enhance egg production by queens. We identified a unique gas condition of royal chambers in the nest of the subterranean termite Reticulitermes speratus, which is characterized by low O2 (15.75%) and high CO2 (4.99%) concentrations. Queens showed significantly greater fecundity under the low O2 and high CO2 gas conditions in the royal chambers than under ambient gas conditions. Quantitative PCR analysis revealed that the royal chamber gas conditions significantly promoted the expression levels of the vitellogenin genes RsVg1, RsVg2 and RsVg3 in queens compared with ambient gas conditions. This study highlights the adaptation of animals that live in closed habitats, which are hypoxic and hypercapnic as the result of their own metabolism, so as to have a high fitness in such environmental conditions.
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Affiliation(s)
- Eisuke Tasaki
- Laboratory of Insect Ecology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwakecho, Kyoto 606-8502, Japan
| | - Yasuyuki Komagata
- Laboratory of Insect Ecology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwakecho, Kyoto 606-8502, Japan
| | - Tatsuya Inagaki
- Laboratory of Insect Ecology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwakecho, Kyoto 606-8502, Japan
| | - Kenji Matsuura
- Laboratory of Insect Ecology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwakecho, Kyoto 606-8502, Japan
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