1
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Lebenzon JE, Toxopeus J. Knock down to level up: Reframing RNAi for invertebrate ecophysiology. Comp Biochem Physiol A Mol Integr Physiol 2024; 297:111703. [PMID: 39029617 DOI: 10.1016/j.cbpa.2024.111703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 07/16/2024] [Accepted: 07/16/2024] [Indexed: 07/21/2024]
Abstract
Comparative ecophysiologists strive to understand physiological problems in non-model organisms, but molecular tools such as RNA interference (RNAi) are under-used in our field. Here, we provide a framework for invertebrate ecophysiologists to use RNAi to answer questions focused on physiological processes, rather than as a tool to investigate gene function. We specifically focus on non-model invertebrates, in which the use of other genetic tools (e.g., genetic knockout lines) is less likely. We argue that because RNAi elicits a temporary manipulation of gene expression, and resources to carry out RNAi are technically and financially accessible, it is an effective tool for invertebrate ecophysiologists. We cover the terminology and basic mechanisms of RNA interference as an accessible introduction for "non-molecular" physiologists, include a suggested workflow for identifying RNAi gene targets and validating biologically relevant gene knockdowns, and present a hypothesis-testing framework for using RNAi to answer common questions in the realm of invertebrate ecophysiology. This review encourages invertebrate ecophysiologists to use these tools and workflows to explore physiological processes and bridge genotypes to phenotypes in their animal(s) of interest.
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Affiliation(s)
- Jacqueline E Lebenzon
- Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4.
| | - Jantina Toxopeus
- Department of Biology, St. Francis Xavier University, 2321 Notre Dame Ave, Antigonish, NS, Canada B2G 2W5
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2
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Güney G, Cedden D, Körnig J, Ulber B, Beran F, Scholten S, Rostás M. Physiological and transcriptional changes associated with obligate aestivation in the cabbage stem flea beetle (Psylliodes chrysocephala). INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2024; 173:104165. [PMID: 39089389 DOI: 10.1016/j.ibmb.2024.104165] [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: 04/15/2024] [Revised: 07/25/2024] [Accepted: 07/25/2024] [Indexed: 08/04/2024]
Abstract
Aestivation is a form of seasonal dormancy observed in various insect species, usually coinciding with the summer season. The cabbage stem flea beetle, Psylliodes chrysocephala (Coleoptera: Chrysomelidae), is a key pest of oilseed rape that obligatorily aestivates as adult in late summer. Since the physiological and transcriptional processes linked to aestivation in P. chrysocephala are still little understood, we analyzed relevant physiological parameters and performed RNA-seq analyses on laboratory-reared beetles in their pre-aestivation, aestivation, and post-aestivation stages. We found that the beetles reached aestivation at 15 days post-eclosion, showing strongly reduced metabolic activity, with less than 50% CO2 production, compared to pre-aestivating individuals. Under constant laboratory conditions, the beetles aestivated for about 25 days. Female beetles reached reproductive maturity at a median of 52 days post-eclosion. Furthermore, aestivating beetles had significantly reduced carbohydrate reserves and increased lipid reserves compared with pre-aestivating beetles, indicating that aestivation is associated with drastic changes in energy metabolism. Aestivating beetles contained 30% less water and their survival rates under high-temperature conditions (30 °C) were 40% higher compared to pre-aestivating beetles. RNA-seq studies showed that, in particular, gene ontology terms related to carbohydrate and lipid metabolism, digestion, and mitochondrial activity were enriched, with clear differences in transcript abundance between beetles in aestivation compared to pre- or post-aestivation. Specifically, mitochondrial transcripts, such as respiratory chain I subunits, and digestion-related transcripts, such as trypsin, were less abundant during aestivation, which supports the idea that aestivation is associated with decreased metabolic activity. This study represents the first exploration of the transcriptomic and physiological processes linked to aestivation in P. chrysocephala.
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Affiliation(s)
- Gözde Güney
- Agricultural Entomology, Department of Crop Sciences, University of Göttingen, D-37077, Göttingen, Germany.
| | - Doga Cedden
- Department of Evolutionary Developmental Genetics, Johann-Friedrich-Blumenbach Institute, GZMB, University of Göttingen, D-37077, Göttingen, Germany
| | - Johannes Körnig
- Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, D-07745, Jena, Germany; Population Ecology Group, Friedrich Schiller University, D-07743, Jena, Germany
| | - Bernd Ulber
- Agricultural Entomology, Department of Crop Sciences, University of Göttingen, D-37077, Göttingen, Germany
| | - Franziska Beran
- Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, D-07745, Jena, Germany; Population Ecology Group, Friedrich Schiller University, D-07743, Jena, Germany
| | - Stefan Scholten
- Division of Crop Plant Genetics, Department of Crop Sciences, University of Göttingen, D-37075, Göttingen, Germany
| | - Michael Rostás
- Agricultural Entomology, Department of Crop Sciences, University of Göttingen, D-37077, Göttingen, Germany.
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3
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Diaz T, Treidel LA, Menze MA, Williams CM, Lebenzon JE. Beclin-mediated Autophagy Drives Dorsal Longitudinal Flight Muscle Histolysis in the Variable Field Cricket, Gryllus lineaticeps. Integr Comp Biol 2024; 64:565-575. [PMID: 38760886 DOI: 10.1093/icb/icae042] [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: 02/29/2024] [Revised: 05/01/2024] [Accepted: 05/06/2024] [Indexed: 05/20/2024] Open
Abstract
Flight muscle histolysis is a widespread strategy used by insects to break down functional flight muscle and modulate the energetic costs associated with flight muscle use and maintenance. The variable field cricket, Gryllus lineaticeps, undergoes histolysis during their transition between dispersal flight and reproduction. Despite the importance of histolysis on insect reproduction and fitness, the molecular mechanisms driving this flight muscle breakdown are not well understood. Here, we show that beclin-mediated autophagy, a conserved lysosomal-dependent degradation process, drives breakdown of dorsal longitudinal flight muscle in female flight-capable G. lineaticeps. We found that female G. lineaticeps activate autophagy in their dorsal longitudinal flight muscle (DLM), but to a greater extent than the neighboring dorsoventral flight muscle (DVM) during histolysis. RNA interference knockdown of beclin, a gene that encodes a critical autophagy initiation protein, delayed DLM histolysis, but did not affect DVM histolysis. This suggests that crickets selectively activate autophagy to break down the DLMs, while maintaining DVM function for other fitness-relevant activities such as walking. Overall, we confirmed that autophagy is a critical pathway used to remodel flight muscle cells during flight muscle histolysis, providing novel insights into the mechanisms underlying a major life history transition between dispersal and reproduction.
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Affiliation(s)
- Tomás Diaz
- Department of Integrative Biology, University of California Berkeley, 2040 Valley Life Sciences Building, Berkeley, CA 94720, USA
| | - Lisa A Treidel
- School of Biological Sciences, University of Nebraska Lincoln, 1104 T Street, Lincoln, NE 68588, USA
| | - Michael A Menze
- Department of Biology, University of Louisville, 139 Life Sciences Bldg. Louisville, KY 40292, USA
| | - Caroline M Williams
- Department of Integrative Biology, University of California Berkeley, 2040 Valley Life Sciences Building, Berkeley, CA 94720, USA
| | - Jacqueline E Lebenzon
- Department of Integrative Biology, University of California Berkeley, 2040 Valley Life Sciences Building, Berkeley, CA 94720, USA
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4
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Thoral E, Dawson NJ, Bettinazzi S, Rodríguez E. An evolving roadmap: using mitochondrial physiology to help guide conservation efforts. CONSERVATION PHYSIOLOGY 2024; 12:coae063. [PMID: 39252884 PMCID: PMC11381570 DOI: 10.1093/conphys/coae063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 08/19/2024] [Accepted: 08/20/2024] [Indexed: 09/11/2024]
Abstract
The crucial role of aerobic energy production in sustaining eukaryotic life positions mitochondrial processes as key determinants of an animal's ability to withstand unpredictable environments. The advent of new techniques facilitating the measurement of mitochondrial function offers an increasingly promising tool for conservation approaches. Herein, we synthesize the current knowledge on the links between mitochondrial bioenergetics, ecophysiology and local adaptation, expanding them to the wider conservation physiology field. We discuss recent findings linking cellular bioenergetics to whole-animal fitness, in the current context of climate change. We summarize topics, questions, methods, pitfalls and caveats to help provide a comprehensive roadmap for studying mitochondria from a conservation perspective. Our overall aim is to help guide conservation in natural populations, outlining the methods and techniques that could be most useful to assess mitochondrial function in the field.
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Affiliation(s)
- Elisa Thoral
- Department of Biology, Section for Evolutionary Ecology, Lund University, Sölvegatan 37, Lund 223 62, Sweden
| | - Neal J Dawson
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Garscube Campus, Bearsden Road, Glasgow, G61 1QH , UK
| | - Stefano Bettinazzi
- Research Department of Genetics, Evolution and Environment, University College London, Darwin Building, 99-105 Gower Street, WC1E 6BT, London, UK
| | - Enrique Rodríguez
- Research Department of Genetics, Evolution and Environment, University College London, Darwin Building, 99-105 Gower Street, WC1E 6BT, London, UK
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5
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Schebeck M, Lehmann P, Laparie M, Bentz BJ, Ragland GJ, Battisti A, Hahn DA. Seasonality of forest insects: why diapause matters. Trends Ecol Evol 2024; 39:757-770. [PMID: 38777634 DOI: 10.1016/j.tree.2024.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 04/27/2024] [Accepted: 04/29/2024] [Indexed: 05/25/2024]
Abstract
Insects have major impacts on forest ecosystems, from herbivory and soil-nutrient cycling to killing trees at a large scale. Forest insects from temperate, tropical, and subtropical regions have evolved strategies to respond to seasonality; for example, by entering diapause, to mitigate adversity and to synchronize lifecycles with favorable periods. Here, we show that distinct functional groups of forest insects; that is, canopy dwellers, trunk-associated species, and soil/litter-inhabiting insects, express a variety of diapause strategies, but do not show systematic differences in diapause strategy depending on functional group. Due to the overall similarities in diapause strategies, we can better estimate the impacts of anthropogenic change on forest insect populations and, consequently, on key ecosystems.
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Affiliation(s)
- Martin Schebeck
- Institute of Forest Entomology, Forest Pathology and Forest Protection, Department of Forest and Soil Sciences, BOKU University, A-1190 Vienna, Austria.
| | - Philipp Lehmann
- Department of Animal Physiology, Zoological Institute and Museum, University of Greifswald, D-17489 Greifswald, Germany; Department of Zoology, Stockholm University, SE-10691 Stockholm, Sweden; Bolin Centre for Climate Research, SE-10691 Stockholm, Sweden
| | | | - Barbara J Bentz
- US Department of Agriculture, Forest Service, Rocky Mountain Research Station, Logan, UT 84321, USA
| | - Gregory J Ragland
- Department of Integrative Biology, University of Colorado-Denver, Denver, CO 80204, USA
| | - Andrea Battisti
- Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padova, I-35020 Legnaro, Italy
| | - Daniel A Hahn
- Department of Entomology and Nematology, University of Florida, Gainesville, FL 32611-0620, USA
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Wang G, Huang L, Zhuang S, Han F, Huang Q, Hao M, Lin G, Chen L, Shen B, Li F, Li X, Chen C, Gao Y, Mock T, Liang J. Resting cell formation in the marine diatom Thalassiosira pseudonana. THE NEW PHYTOLOGIST 2024; 243:1347-1360. [PMID: 38402560 DOI: 10.1111/nph.19646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 02/08/2024] [Indexed: 02/26/2024]
Abstract
Resting cells represent a survival strategy employed by diatoms to endure prolonged periods of unfavourable conditions. In the oceans, many diatoms sink at the end of their blooming season and therefore need to endure cold and dark conditions in the deeper layers of the water column. How they survive these conditions is largely unknown. We conducted an integrative analysis encompassing methods from histology, physiology, biochemistry, and genetics to reveal the biological mechanism of resting-cell formation in the model diatom Thalassiosira pseudonana. Resting-cell formation was triggered by a decrease in light and temperature with subsequent catabolism of storage compounds. Resting cells were characterised by an acidic and viscous cytoplasm and altered morphology of the chloroplast ultrastructure. The formation of resting cells in T. pseudonana is an energy demanding process required for a biophysical alteration of the cytosol and chloroplasts to endure the unfavourable conditions of the deeper ocean as photosynthetic organisms. However, most resting cells (> 90%) germinate upon return to favorable growth conditions.
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Affiliation(s)
- Guangning Wang
- School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen Key Laboratory of Plant Genetics, Xiamen University, Xiamen, 361102, Fujian, China
| | - Lu Huang
- School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen Key Laboratory of Plant Genetics, Xiamen University, Xiamen, 361102, Fujian, China
| | - Shanshan Zhuang
- School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen Key Laboratory of Plant Genetics, Xiamen University, Xiamen, 361102, Fujian, China
| | - Fang Han
- School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen Key Laboratory of Plant Genetics, Xiamen University, Xiamen, 361102, Fujian, China
| | - Qianqian Huang
- School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen Key Laboratory of Plant Genetics, Xiamen University, Xiamen, 361102, Fujian, China
| | - Mengyuan Hao
- School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen Key Laboratory of Plant Genetics, Xiamen University, Xiamen, 361102, Fujian, China
| | - Guifang Lin
- School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen Key Laboratory of Plant Genetics, Xiamen University, Xiamen, 361102, Fujian, China
| | - Longnan Chen
- School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen Key Laboratory of Plant Genetics, Xiamen University, Xiamen, 361102, Fujian, China
| | - Biying Shen
- School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen Key Laboratory of Plant Genetics, Xiamen University, Xiamen, 361102, Fujian, China
| | - Feng Li
- School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen Key Laboratory of Plant Genetics, Xiamen University, Xiamen, 361102, Fujian, China
| | - Xuesong Li
- School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen Key Laboratory of Plant Genetics, Xiamen University, Xiamen, 361102, Fujian, China
| | - Changping Chen
- School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen Key Laboratory of Plant Genetics, Xiamen University, Xiamen, 361102, Fujian, China
| | - Yahui Gao
- School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen Key Laboratory of Plant Genetics, Xiamen University, Xiamen, 361102, Fujian, China
- State Key Laboratory of Marine Environment Science, Xiamen University, Xiamen, 361102, Fujian, China
| | - Thomas Mock
- School of Environmental Sciences, University of East Anglia (UEA), Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Junrong Liang
- School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen Key Laboratory of Plant Genetics, Xiamen University, Xiamen, 361102, Fujian, China
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7
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Cedden D, Güney G, Toprak U. The integral role of de novo lipogenesis in the preparation for seasonal dormancy. Proc Natl Acad Sci U S A 2024; 121:e2406194121. [PMID: 38990942 PMCID: PMC11260141 DOI: 10.1073/pnas.2406194121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Accepted: 06/11/2024] [Indexed: 07/13/2024] Open
Abstract
Animals can alter their body compositions in anticipation of dormancy to endure seasons with limited food availability. Accumulation of lipid reserves, mostly in the form of triglycerides (TAGs), is observed during the preparation for dormancy in diverse animals, including insects (diapause) and mammals (hibernation). However, the mechanisms involved in the regulation of lipid accumulation and the ecological consequences of failure to accumulate adequate lipid stores in preparation for animal dormancy remain understudied. In the broadest sense, lipid reserves can be accumulated in two ways: the animal either receives lipids directly from the environment or converts the sugars and amino acids present in food to fatty acids through de novo lipogenesis and then to TAGs. Here, we show that preparation for diapause in the Colorado potato beetle (Leptinotarsa decemlineata) involves orchestrated upregulation of genes involved in lipid metabolism with a transcript peak in 8- and 10-d-old diapause-destined insects. Regulation at the transcript abundance level was associated with the accumulation of substantial fat stores. Furthermore, the knockdown of de novo lipogenesis enzymes (ACCase and FAS-1) prolonged the preparatory phase, while the knockdown of fatty acid transportation genes shortened the preparatory phase. Our findings suggest a model in which the insects dynamically decide when to transition from the preparation phase into diapause, depending on the progress in lipid accumulation through de novo lipogenesis.
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Affiliation(s)
- Doga Cedden
- Molecular Entomology Laboratory, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara06110, Türkiye
- Department of Evolutionary Developmental Genetics, Johann-Friedrich-Blumenbach Institute, Göttingen Center for Molecular Biosciences, University of Göttingen, Göttingen37077, Germany
| | - Gözde Güney
- Molecular Entomology Laboratory, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara06110, Türkiye
- Agricultural Entomology, Department of Crop Sciences, University of Göttingen, Göttingen37077, Germany
| | - Umut Toprak
- Molecular Entomology Laboratory, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara06110, Türkiye
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Dhungana P, Wei X, Meuti ME, Sim C. Genome-wide identification of PAR domain protein 1 (PDP1) targets through ChIP-seq reveals the regulation of diapause-specific characteristics in Culex pipiens. INSECT MOLECULAR BIOLOGY 2024. [PMID: 38989821 DOI: 10.1111/imb.12943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 06/25/2024] [Indexed: 07/12/2024]
Abstract
Insects use seasonal diapause as an alternative strategy to endure adverse seasons. This developmental trajectory is induced by environmental cues like short-day lengths in late summer and early fall, but how insects measure day length is unknown. The circadian clock has been implicated in regulating photoperiodic or seasonal responses in many insects, including the Northern house mosquito, Culex pipiens, which enters adult diapause. To investigate the potential control of diapause by circadian control, we employed ChIP-sequencing to identify the downstream targets of a circadian transcription factor, PAR domain protein 1 (PDP1), that contribute to the hallmark features of diapause. We identified the nearest genes in a 10 kb region of the anticipated PDP1 binding sites, listed prospective targets and searched for PDP1-specific binding sites. By examining the functional relevance to diapause-specific behaviours and modifications such as metabolic pathways, lifespan extension, cell cycle regulation and stress tolerance, eight genes were selected as targets and validated using ChIP-qPCR. In addition, qRT-PCR demonstrated that the mRNA abundance of PDP1 targets increased in the heads of diapausing females during the middle of the scotophase (ZT17) compared with the early photophase (ZT1), in agreement with the peak and trough of PDP1 abundance. Thus, our investigation uncovered the mechanism by which PDP1 might generate a diapause phenotype in insects.
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Affiliation(s)
| | - Xueyan Wei
- Department of Biology, Baylor University, Waco, Texas, USA
| | - Megan E Meuti
- Department of Entomology, College of Food, Agricultural, and Environmental Sciences, The Ohio State University, Columbus, Ohio, USA
| | - Cheolho Sim
- Department of Biology, Baylor University, Waco, Texas, USA
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Boardman L. Cross-talk between low temperature and other environmental factors. CURRENT OPINION IN INSECT SCIENCE 2024; 63:101193. [PMID: 38490451 DOI: 10.1016/j.cois.2024.101193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Revised: 03/07/2024] [Accepted: 03/11/2024] [Indexed: 03/17/2024]
Abstract
Low temperatures are rarely experienced in isolation. The impacts of low temperatures on insects can be exacerbated or alleviated by the addition of other environmental factors, including, for example, desiccation, hypoxia, or infection. One way in which environmental factors can interact is through cross-talk where different factors enact common signaling pathways. In this review, I highlight the breadth of abiotic and biotic factors that can interact with low-temperature tolerance in both natural and artificial environments; and discuss some of the candidate pathways that are possibly responsible for cross-talk between several factors. Specifically, I discuss three interesting candidates: the neurohormone octopamine, circadian clock gene vrille, and microbes. Finally, I discuss applications of cross-talk studies, and provide recommendations for researchers.
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Affiliation(s)
- Leigh Boardman
- Department of Biological Sciences, University of Memphis, Memphis, TN 38152, USA.
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10
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Rondot A, Darveau CA. Metabolic Rate Suppression and Maintenance of Flight Muscle Metabolic Capacity during Diapause in Bumble Bee ( Bombus impatiens) Queens. ECOLOGICAL AND EVOLUTIONARY PHYSIOLOGY 2024; 97:144-156. [PMID: 38875138 DOI: 10.1086/730587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2024]
Abstract
AbstractThe common eastern bumble bee (Bombus impatiens) queens endure cold winter months by entering a diapause state. During this overwintering period, these animals use stored energy reserves while maintaining a low metabolic rate. This study investigates changes in the metabolic rate of bumble bee queens during diapause-like laboratory conditions and the potential reorganization of the flight muscle metabolic properties during this period. We first confirmed the hypometabolic state of queens during diapause in the laboratory, which lowered their resting metabolic rate to less than 5% of normal resting values. Body mass decreased during diapause, body composition changed where carbohydrates decreased initially, and later protein declined, with a similar trend for lipid content. Using cellular respirometry, we determined the capacity of the flight muscle cells of bumble bee queens to use various metabolic fuels and whether this capacity changes during the progression of diapause to favor stored lipid-derived substrates. Queens showed a low capacity to oxidize the amino acid proline, compared with workers, and their capacity to oxidize all metabolic substrates did not change during a 4-mo diapause period in the laboratory. We also show no detectable ability to oxidize fatty acid by flight muscle mitochondria in this species. The metabolic properties of flight muscle tissue were further characterized using metabolic enzyme activity profiles showing little change during diapause, indicating that profound metabolic suppression is induced without major changes in muscle metabolic phenotypes. Overall, B. impatiens queens undergo diapause while maintaining flight muscle capacity under the conditions used.
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11
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Melicher D, Torson AS, Yocum GD, Bosch J, Kemp WP, Bowsher JH, Rinehart JP. Metabolic and transcriptomic characterization of summer and winter dormancy in the solitary bee, Osmia lignaria. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2024; 166:104074. [PMID: 38228213 DOI: 10.1016/j.ibmb.2024.104074] [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: 09/20/2023] [Revised: 01/08/2024] [Accepted: 01/13/2024] [Indexed: 01/18/2024]
Abstract
The solitary bee Osmia lignaria is a native pollinator in North America with growing economic importance. The life cycle of O. lignaria provides a unique opportunity to compare the physiological and molecular mechanisms underlying two ecologically contrasting dormancies within the same species. O. lignaria prepupae become dormant during the summer to avoid high temperatures. Shortly after adult eclosion, they enter a second dormancy and overwinter as diapausing adults. To compare these two dormancies, we measured metabolic rates and gene expression across development as bees initiate, maintain, and terminate both prepupal (summer) and adult (overwintering) dormancies. We observed a moderate temperature-independent decrease in gas exchange during both the prepupal dormancy after cocoon spinning (45 %) and during adult diapause after eclosion (60 %). We sequenced and assembled a high-quality reference genome from a single haploid male bee with a contiguous n50 of 5.5 Mbp to facilitate our transcriptomic analysis. The transcriptomes of dormant prepupae and diapausing adults clustered into distinct groups more closely associated with life stage than dormancy status. Membrane transport, membrane-bound cellular components, oxidoreductase activity, glutathione metabolism, and transcription factor activity increased during adult diapause, relative to prepupal dormancy. Further, the transcriptomes of adults in diapause clustered into two groups, supporting multiple phases of diapause during winter. Late adult diapause was associated with gene expression profiles supporting increased insulin/IGF, juvenile hormone, and ecdysone signaling.
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Affiliation(s)
- Dacotah Melicher
- Edward T. Schafer Agricultural Research Center, U.S. Department of Agriculture/Agricultural Research Service, 1616 Albrecht Boulevard North, Fargo, ND, 58102, USA
| | - Alex S Torson
- Edward T. Schafer Agricultural Research Center, U.S. Department of Agriculture/Agricultural Research Service, 1616 Albrecht Boulevard North, Fargo, ND, 58102, USA.
| | - George D Yocum
- Edward T. Schafer Agricultural Research Center, U.S. Department of Agriculture/Agricultural Research Service, 1616 Albrecht Boulevard North, Fargo, ND, 58102, USA
| | - Jordi Bosch
- CREAF, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
| | - William P Kemp
- Edward T. Schafer Agricultural Research Center, U.S. Department of Agriculture/Agricultural Research Service, 1616 Albrecht Boulevard North, Fargo, ND, 58102, USA
| | - Julia H Bowsher
- Department of Biological Sciences, North Dakota State University, 1340 Bolley Drive, 218 Stevens Hall, Fargo, ND, 58102, USA
| | - Joseph P Rinehart
- Edward T. Schafer Agricultural Research Center, U.S. Department of Agriculture/Agricultural Research Service, 1616 Albrecht Boulevard North, Fargo, ND, 58102, USA
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12
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Štětina T, Koštál V. Extracellular freezing induces a permeability transition in the inner membrane of muscle mitochondria of freeze-sensitive but not freeze-tolerant Chymomyza costata larvae. Front Physiol 2024; 15:1358190. [PMID: 38384799 PMCID: PMC10880108 DOI: 10.3389/fphys.2024.1358190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 01/29/2024] [Indexed: 02/23/2024] Open
Abstract
Background: Many insect species have evolved the ability to survive extracellular freezing. The search for the underlying principles of their natural freeze tolerance remains hampered by our poor understanding of the mechanistic nature of freezing damage itself. Objectives: Here, in search of potential primary cellular targets of freezing damage, we compared mitochondrial responses (changes in morphology and physical integrity, respiratory chain protein functionality, and mitochondrial inner membrane (IMM) permeability) in freeze-sensitive vs. freeze-tolerant phenotypes of the larvae of the drosophilid fly, Chymomyza costata. Methods: Larvae were exposed to freezing stress at -30°C for 1 h, which is invariably lethal for the freeze-sensitive phenotype but readily survived by the freeze-tolerant phenotype. Immediately after melting, the metabolic activity of muscle cells was assessed by the Alamar Blue assay, the morphology of muscle mitochondria was examined by transmission electron microscopy, and the functionality of the oxidative phosphorylation system was measured by Oxygraph-2K microrespirometry. Results: The muscle mitochondria of freeze-tolerant phenotype larvae remained morphologically and functionally intact after freezing stress. In contrast, most mitochondria of the freeze-sensitive phenotype were swollen, their matrix was diluted and enlarged in volume, and the structure of the IMM cristae was lost. Despite this morphological damage, the electron transfer chain proteins remained partially functional in lethally frozen larvae, still exhibiting strong responses to specific respiratory substrates and transferring electrons to oxygen. However, the coupling of electron transfer to ATP synthesis was severely impaired. Based on these results, we formulated a hypothesis linking the observed mitochondrial swelling to a sudden loss of barrier function of the IMM.
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Affiliation(s)
| | - Vladimír Koštál
- Institute of Entomology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czechia
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13
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Patil YN, Gnaiger E, Landry AP, Leno ZJ, Hand SC. OXPHOS capacity is diminished and the phosphorylation system inhibited during diapause in an extremophile, embryos of Artemia franciscana. J Exp Biol 2024; 227:jeb245828. [PMID: 38099471 DOI: 10.1242/jeb.245828] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 12/04/2023] [Indexed: 01/23/2024]
Abstract
Diapause exhibited by embryos of Artemia franciscana is accompanied by severe arrest of respiration. A large fraction of this depression is attributable to downregulation of trehalose catabolism that ultimately restricts fuel to mitochondria. This study now extends knowledge on the mechanism by revealing metabolic depression is heightened by inhibitions within mitochondria. Compared with that in embryo lysates during post-diapause, oxidative phosphorylation (OXPHOS) capacity P is depressed during diapause when either NADH-linked substrates (pyruvate and malate) for electron transfer (electron transfer capacity, E) through respiratory Complex I or the Complex II substrate succinate are used. When pyruvate, malate and succinate were combined, respiratory inhibition by the phosphorylation system in diapause lysates was discovered as judged by P/E flux control ratios (two-way ANOVA; F1,24=38.78; P<0.0001). Inhibition was eliminated as the diapause extract was diluted (significant interaction term; F2,24=9.866; P=0.0007), consistent with the presence of a diffusible inhibitor. One candidate is long-chain acyl-CoA esters known to inhibit the adenine nucleotide translocator. Addition of oleoyl-CoA to post-diapause lysates markedly decreased the P/E ratio to 0.40±0.07 (mean±s.d.; P=0.002) compared with 0.79±0.11 without oleoyl-CoA. Oleoyl-CoA inhibits the phosphorylation system and may be responsible for the depressed P/E in lysates from diapause embryos. With isolated mitochondria, depression of P/E by oleoyl-CoA was fully reversed by addition of l-carnitine (control versus recovery with l-carnitine, P=0.338), which facilitates oleoyl-CoA transport into the matrix and elimination by β-oxidation. In conclusion, severe metabolic arrest during diapause promoted by restricting glycolytic carbon to mitochondria is reinforced by depression of OXPHOS capacity and the phosphorylation system.
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Affiliation(s)
- Yuvraj N Patil
- Department of Biological Sciences, Division of Cellular, Developmental and Integrative Biology, Louisiana State University, Baton Rouge, LA 70803, USA
| | | | - Alexander P Landry
- Department of Biological Sciences, Division of Cellular, Developmental and Integrative Biology, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Zachary J Leno
- Department of Biological Sciences, Division of Cellular, Developmental and Integrative Biology, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Steven C Hand
- Department of Biological Sciences, Division of Cellular, Developmental and Integrative Biology, Louisiana State University, Baton Rouge, LA 70803, USA
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14
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Álvarez HA, Ruano F. Phenotypic plasticity of a winter-diapause mechanism copes with the effects of summer global warming in an ectothermic predator. Biol Lett 2024; 20:20230481. [PMID: 38229555 PMCID: PMC10792392 DOI: 10.1098/rsbl.2023.0481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 12/21/2023] [Indexed: 01/18/2024] Open
Abstract
To adapt to changes in temperature, animals tend to invest more energy in thermal tolerance to enhance survival, which can have simultaneous costs on plastic traits. Would a decrease in genetic variability, due to global warming, affect the ability of populations with existing metabolic regulatory mechanisms to cope with extreme temperatures? To address this question, we conducted a series of experiments based on the A1B scenario of global warming, assessing within-population genetic variance in (a) morphological traits, (b) metabolic rate allometries, and (c) survival of a winter-diapausing predator ectotherm. Our study focused on the lacewing species Chrysoperla pallida, using both exogamic and endogamic artificial genetic lines. We discovered that both lines use their winter-diapausing phenotype to adapt to summer extreme temperatures caused by extreme heating conditions, but the exogamic line is prone to express phenotypic plasticity in metabolic scaling, with a trade-off between body size and mandible size, i.e. larger individuals tended to develop smaller mandibles to better survive. These findings highlight the significance of substantial phenotypic plasticity and pre-existing metabolic regulatory mechanisms in enabling ectotherms to cope with potential extreme heating occurring in global warming.
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Affiliation(s)
- Hugo Alejandro Álvarez
- Department of Biogeography and Global Change, CSIC – National Museum of Natural Sciences, Madrid, Comunidad de Madrid, Spain
- Department of Zoology, University of Granada, Granada, Andalucía, Spain
| | - Francisca Ruano
- Department of Zoology, University of Granada, Granada, Andalucía, Spain
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15
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Roberts KT, Szejner-Sigal A, Lehmann P. Seasonal energetics: are insects constrained by energy during dormancy? J Exp Biol 2023; 226:jeb245782. [PMID: 37921417 DOI: 10.1242/jeb.245782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2023]
Abstract
In seasonal environments, many animals, including insects, enter dormancy, where they are limited to a fixed energy budget. The inability to replenish energetic stores during these periods suggests insects should be constrained by pre-dormancy energy stores. Over the last century, the community of researchers working on survival during dormancy has operated under the strong assumption that energy limitation is a key fitness trait driving the evolution of seasonal strategies. That is, energy use has to be minimized during dormancy because insects otherwise run out of energy and die during dormancy, or are left with too little energy to complete development, reproductive maturation or other costly post-dormancy processes such as dispersal or nest building. But if energy is so strongly constrained during dormancy, how can some insects - even within the same species and population - be dormant in very warm environments or show prolonged dormancy for many successive years? In this Commentary, we discuss major assumptions regarding dormancy energetics and outline cases where insects appear to align with our assumptions and where they do not. We then highlight several research directions that could help link organismal energy use with landscape-level changes. Overall, the optimal energetic strategy during dormancy might not be to simply minimize metabolic rate, but instead to maintain a level that matches the demands of the specific life-history strategy. Given the influence of temperature on energy use rates of insects in winter, understanding dormancy energetic strategies is critical in order to determine the potential impacts of climate change on insects in seasonal environments.
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Affiliation(s)
- Kevin T Roberts
- Department of Zoology, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Andre Szejner-Sigal
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Philipp Lehmann
- Department of Zoology, Stockholm University, SE-106 91 Stockholm, Sweden
- Department of Animal Physiology, Zoological Institute and Museum, University of Greifswald, 17489 Greifswald, Germany
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16
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Willot Q, du Toit A, de Wet S, Huisamen EJ, Loos B, Terblanche JS. Exploring the connection between autophagy and heat-stress tolerance in Drosophila melanogaster. Proc Biol Sci 2023; 290:20231305. [PMID: 37700658 PMCID: PMC10498041 DOI: 10.1098/rspb.2023.1305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 08/16/2023] [Indexed: 09/14/2023] Open
Abstract
Mechanisms aimed at recovering from heat-induced damages are closely associated with the ability of ectotherms to survive exposure to stressful temperatures. Autophagy, a ubiquitous stress-responsive catabolic process, has recently gained renewed attention as one of these mechanisms. By increasing the turnover of cellular structures as well as the clearance of long-lived protein and protein aggregates, the induction of autophagy has been linked to increased tolerance to a range of abiotic stressors in diverse ectothermic organisms. However, whether a link between autophagy and heat-tolerance exists in insect models remains unclear despite broad ecophysiological implications thereof. Here, we explored the putative association between autophagy and heat-tolerance using Drosophila melanogaster as a model. We hypothesized that (i) heat-stress would cause an increase of autophagy in flies' tissues, and (ii) rapamycin exposure would trigger a detectable autophagic response in adults and increase their heat-tolerance. In line with our hypothesis, we report that flies exposed to heat-stress present signs of protein aggregation and appear to trigger an autophagy-related homoeostatic response as a result. We further show that rapamycin feeding causes the systemic effect associated with target of rapamycin (TOR) inhibition, induces autophagy locally in the fly gut, and increases the heat-stress tolerance of individuals. These results argue in favour of a substantial contribution of autophagy to the heat-stress tolerance mechanisms of insects.
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Affiliation(s)
- Quentin Willot
- Centre for Invasion Biology, Department of Conservation Ecology & Entomology, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Andre du Toit
- Department of Physiological Sciences, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Sholto de Wet
- Department of Physiological Sciences, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Elizabeth J. Huisamen
- Centre for Invasion Biology, Department of Conservation Ecology & Entomology, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Ben Loos
- Department of Physiological Sciences, Stellenbosch University, Stellenbosch 7600, South Africa
| | - John S. Terblanche
- Centre for Invasion Biology, Department of Conservation Ecology & Entomology, Stellenbosch University, Stellenbosch 7600, South Africa
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17
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Roberts KT, Stillman JH, Rank NE, Dahlhoff EP, Bracewell RR, Elmore J, Williams CM. Transcriptomic evidence indicates that montane leaf beetles prioritize digestion and reproduction in a sex-specific manner during emergence from dormancy. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART D, GENOMICS & PROTEOMICS 2023; 47:101088. [PMID: 37210884 DOI: 10.1016/j.cbd.2023.101088] [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: 02/13/2023] [Revised: 05/10/2023] [Accepted: 05/11/2023] [Indexed: 05/23/2023]
Abstract
During winter, many organisms conserve resources by entering dormancy, suppressing metabolism and biosynthesis. The transition out of winter dormancy to summer activity requires a quick reversal of this suppression, in order to exploit now-favorable environmental conditions. To date, mechanisms by which winter climate variation affects this transition remains unelucidated. Here we experimentally manipulated snow cover for naturally overwintering montane leaf beetles (Chrysomela aeneicollis), and profiled changes in gene expression during the transition out of dormancy in spring. Upon emergence, beetles up-regulate transcripts associated with digestion and nutrient acquisition and down regulate those associated with lipid metabolism, suggesting a shift away from utilizing stored lipid and towards digestion of carbohydrate-rich host plant tissue. Development of digestive capacity is followed by up-regulation of transcripts associated with reproduction; a transition that occurs earlier in females than males. Snow manipulation strongly affected the ground thermal regime and correspondingly gene expression profiles, with beetles showing a delayed up-regulation of reproduction in the dry compared to snowy plots. This suggests that winter conditions can alter the timing and prioritization of processes during emergence from dormancy, potentially magnifying the effects of declining snow cover in the Sierra's and other snowy mountains.
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Affiliation(s)
- Kevin T Roberts
- Department of Integrative Biology, University of California, Berkeley, CA, USA; Department of Zoology, Stockholm University, Stockholm, Sweden.
| | - Jonathon H Stillman
- Department of Integrative Biology, University of California, Berkeley, CA, USA; Department of Biology, San Francisco State University, San Francisco, CA, USA
| | - Nathan E Rank
- Department of Biology, Sonoma State University, Rohnert Park, CA, USA
| | | | - Ryan R Bracewell
- Department of Integrative Biology, University of California, Berkeley, CA, USA; Department of Biology, Indiana University, Bloomington, IN, USA
| | - Joanna Elmore
- Department of Biology, Sonoma State University, Rohnert Park, CA, USA
| | - Caroline M Williams
- Department of Integrative Biology, University of California, Berkeley, CA, USA
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18
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Lebenzon JE, Overgaard J, Jørgensen LB. Chilled, starved or frozen: Insect mitochondrial adaptations to overcome the cold. CURRENT OPINION IN INSECT SCIENCE 2023:101076. [PMID: 37331596 DOI: 10.1016/j.cois.2023.101076] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/13/2023] [Accepted: 06/13/2023] [Indexed: 06/20/2023]
Abstract
Physiological adaptations to tackle cold exposure are crucial for insects living in temperate and arctic environments and here we review how cold adaptation is manifested in terms of mitochondrial function. Cold challenges are diverse, and different insect species have evolved metabolic and mitochondrial adaptations to: i) energize homeostatic regulation at low temperature, ii) stretch energy reserves during prolonged cold exposure, and iii) preserve structural organization of organelles following extracellular freezing. While the literature is still sparse, our review suggests that cold-adapted insects preserve ATP production at low temperatures by maintaining preferred mitochondrial substrate oxidation, which is otherwise challenged in cold-sensitive species. Chronic cold exposure and metabolic depression during dormancy is linked to reduced mitochondrial metabolism and may involve mitochondrial degradation. Finally, adaptation to extracellular freezing could be associated with superior structural integrity of the mitochondrial inner membrane following freezing which is linked to cellular and organismal survival.
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Affiliation(s)
- Jacqueline E Lebenzon
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
| | - Johannes Overgaard
- Section for Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark.
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Torson AS, Bowman S, Doucet D, Roe AD, Sinclair BJ. Molecular signatures of diapause in the Asian longhorned beetle: Gene expression. CURRENT RESEARCH IN INSECT SCIENCE 2023; 3:100054. [PMID: 37033896 PMCID: PMC10074507 DOI: 10.1016/j.cris.2023.100054] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 03/03/2023] [Accepted: 03/08/2023] [Indexed: 05/30/2023]
Abstract
Most previous studies on gene expression during insect diapause do not address among-tissue variation in physiological processes. We measured transcriptomic changes during larval diapause in the Asian longhorned beetle, Anoplophora glabripennis (Coleoptera: Cerambycidae). We conducted RNA-seq on fat body, the supraesophageal ganglion, midgut, hindgut, and Malpighian tubules during pre-diapause, diapause maintenance, post-diapause quiescence, and post-diapause development. We observed a small, but consistent, proportion of genes within each gene expression profile that were shared among tissues, lending support for a core set of diapause-associated genes whose expression is tissue-independent. We evaluated the overarching hypotheses that diapause would be associated with cell cycle arrest, developmental arrest, and increased stress tolerance and found evidence of repressed TOR and insulin signaling, reduced cell cycle activity and increased capacity of stress response via heat shock protein expression and remodeling of the cytoskeleton. However, these processes varied among tissues, with the brain and fat body appearing to maintain higher levels of cellular activity during diapause than the midgut or Malpighian tubules. We also observed temperature-dependent changes in gene expression during diapause maintenance, particularly in genes related to the heat shock response and MAPK, insulin, and TOR signaling pathways. Additionally, we provide evidence for epigenetic reorganization during the diapause/post-diapause quiescence transition and expression of genes involved in post-translational modification, highlighting the need for investigations of the protein activity of these candidate genes and processes. We conclude that diapause development is coordinated via diverse tissue-specific gene expression profiles and that canonical diapause phenotypes vary among tissues.
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Affiliation(s)
- Alex S. Torson
- Department of Biology, The University of Western Ontario, London ON N6A 5B7, Canada
- Biosciences Research Laboratory, USDA-ARS Edward T. Schafer Agricultural Research Center, Fargo, ND 58102, United States
| | - Susan Bowman
- Great Lakes Forestry Centre, Natural Resources Canada, Canadian Forest Service, Sault Ste. Marie, Ontario P6A 2E5, Canada
| | - Daniel Doucet
- Great Lakes Forestry Centre, Natural Resources Canada, Canadian Forest Service, Sault Ste. Marie, Ontario P6A 2E5, Canada
| | - Amanda D. Roe
- Great Lakes Forestry Centre, Natural Resources Canada, Canadian Forest Service, Sault Ste. Marie, Ontario P6A 2E5, Canada
| | - Brent J. Sinclair
- Department of Biology, The University of Western Ontario, London ON N6A 5B7, Canada
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20
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Abstract
Diapause, a stage-specific developmental arrest, is widely exploited by insects to bridge unfavorable seasons. Considerable progress has been made in understanding the ecology, physiology and evolutionary implications of insect diapause, yet intriguing questions remain. A more complete understanding of diapause processes on Earth requires a better geographic spread of investigations, including more work in the tropics and at high latitudes. Questions surrounding energy management and trade-offs between diapause and non-diapause remain understudied. We know little about how maternal effects direct the diapause response, and regulators of prolonged diapause are also poorly understood. Numerous factors that were recently linked to diapause are still waiting to be placed in the regulatory network leading from photoreception to engagement of the diapause program. These factors include epigenetic processes and small noncoding RNAs, and emerging data also suggest a role for the microbiome in diapause regulation. Another intriguing feature of diapause is the complexity of the response, resulting in a diverse suite of responses that comprise the diapause syndrome. Select transcription factors likely serve as master switches turning on these diverse responses, but we are far from understanding the full complexity. The richness of species displaying diapause offers a platform for seeking common components of a 'diapause toolbox'. Across latitudes, during invasion events and in a changing climate, diapause offers grand opportunities to probe evolutionary change and speciation. At a practical level, diapause responses can be manipulated for insect control and long-term storage. Diapausing insects also contain a treasure trove of pharmacological compounds and offer promising models for human health.
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Affiliation(s)
- David L Denlinger
- Departments of Entomology and Evolution, Ecology and Organismal Biology, Ohio State University, Columbus, OH 43210, USA
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Mmp-induced fat body cell dissociation promotes pupal development and moderately averts pupal diapause by activating lipid metabolism. Proc Natl Acad Sci U S A 2023; 120:e2215214120. [PMID: 36574695 PMCID: PMC9910469 DOI: 10.1073/pnas.2215214120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
In Lepidoptera and Diptera, the fat body dissociates into single cells in nondiapause pupae, but it does not dissociate in diapause pupae until diapause termination. Using the cotton bollworm, Helicoverpa armigera, as a model of pupal diapause insects, we illustrated the catalytic mechanism and physiological importance of fat body cell dissociation in regulating pupal development and diapause. In nondiapause pupae, cathepsin L (CatL) activates matrix metalloproteinases (Mmps) that degrade extracellular matrix proteins and cause fat body cell dissociation. Mmp-induced fat body cell dissociation activates lipid metabolism through transcriptional regulation, and the resulting energetic supplies increase brain metabolic activity (i.e., mitochondria respiration and insulin signaling) and thus promote pupal development. In diapause pupae, low activities of CatL and Mmps prevent fat body cell dissociation and lipid metabolism from occurring, maintaining pupal diapause. Importantly, as demonstrated by chemical inhibitor treatments and CRISPR-mediated gene knockouts, Mmp inhibition delayed pupal development and moderately increased the incidence of pupal diapause, while Mmp stimulation promoted pupal development and moderately averted pupal diapause. This study advances our recent understanding of fat body biology and insect diapause regulation.
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22
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Borowiec BG. Mitochondria on demand for overwintering beetles. J Exp Biol 2022. [DOI: 10.1242/jeb.243523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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