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Weiss L, McBride CS. Mosquitoes as a model for understanding the neural basis of natural behaviors. Curr Opin Neurobiol 2024; 87:102897. [PMID: 39002351 DOI: 10.1016/j.conb.2024.102897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 06/18/2024] [Accepted: 06/19/2024] [Indexed: 07/15/2024]
Abstract
Mosquito behaviors have been the subject of extensive research for over a century due to their role in the spread of human disease. However, these behaviors are also beginning to be appreciated as excellent models for neurobiological research in their own right. Many of the same behaviors and sensory abilities that help mosquitoes survive and reproduce alongside humans represent striking examples of generalizable phenomena of longstanding neurobiological interest. In this review, we highlight four prominent examples that promise new insight into (1) precise circadian tuning of sensory systems, (2) processing of complex natural odors, (3) multisensory integration, and (4) modulation of behavior by internal states.
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Affiliation(s)
- Lukas Weiss
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA; Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA
| | - Carolyn S McBride
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA; Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA.
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Dou X, Chen K, Brown MR, Strand MR. Reciprocal interactions between neuropeptide F and RYamide regulate host attraction in the mosquito Aedes aegypti. Proc Natl Acad Sci U S A 2024; 121:e2408072121. [PMID: 38950363 PMCID: PMC11252962 DOI: 10.1073/pnas.2408072121] [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: 04/22/2024] [Accepted: 05/15/2024] [Indexed: 07/03/2024] Open
Abstract
Female mosquitoes produce eggs in gonadotrophic cycles that are divided between a previtellogenic and vitellogenic phase. Previtellogenic females consume water and sugar sources like nectar while also being attracted to hosts for blood feeding. Consumption of a blood meal activates the vitellogenic phase, which produces mature eggs and suppresses host attraction. In this study, we tested the hypothesis that neuropeptide Y-like hormones differentially modulate host attraction behavior in the mosquito Aedes aegypti. A series of experiments collectively indicated that enteroendocrine cells (EECs) in the posterior midgut produce and release neuropeptide F (NPF) into the hemolymph during the previtellogenic phase which stimulates attraction to humans and biting behavior. Consumption of a blood meal, which primarily consists of protein by dry weight, down-regulated NPF in EECs until mature eggs developed, which was associated with a decline in hemolymph titer. NPF depletion depended on protein digestion but was not associated with EEC loss. Other experiments showed that neurons in the terminal ganglion extend axons to the posterior midgut and produce RYamide, which showed evidence of increased secretion into circulation after a blood meal. Injection of RYamide-1 and -2 into previtellogenic females suppressed host attraction, while coinjection of RYamides with or without short NPF-2 also inhibited the host attraction activity of NPF. Overall, our results identify NPF and RYamide as gut-associated hormones in A. aegypti that link host attraction behavior to shifts in diet during sequential gonadotrophic cycles.
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Affiliation(s)
- Xiaoyi Dou
- Department of Entomology, University of Georgia, Athens, GA30602
| | - Kangkang Chen
- Department of Entomology, University of Georgia, Athens, GA30602
| | - Mark R. Brown
- Department of Entomology, University of Georgia, Athens, GA30602
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Chen K, Dou X, Eum JH, Harrison RE, Brown MR, Strand MR. Insulin-like peptides and ovary ecdysteroidogenic hormone differentially stimulate physiological processes regulating egg formation in the mosquito Aedes aegypti. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2023; 163:104028. [PMID: 37913852 PMCID: PMC10842226 DOI: 10.1016/j.ibmb.2023.104028] [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: 09/24/2023] [Revised: 10/12/2023] [Accepted: 10/23/2023] [Indexed: 11/03/2023]
Abstract
Mosquitoes including Aedes aegypti are human disease vectors because females must blood feed to produce and lay eggs. Blood feeding triggers insulin-insulin growth factor signaling (IIS) which regulates several physiological processes required for egg development. A. aegypti encodes 8 insulin-like peptides (ILPs) and one insulin-like receptor (IR) plus ovary ecdysteroidogenic hormone (OEH) that also activates IIS through the OEH receptor (OEHR). In this study, we assessed the expression of A. aegypti ILPs and OEH during a gonadotrophic cycle and produced each that were functionally characterized to further understand their roles in regulating egg formation. All A. aegypti ILPs and OEH were expressed during a gonadotrophic cycle. Five ILPs (1, 3, 4, 7, 8) and OEH were specifically expressed in the head, while antibodies to ILP3 and OEH indicated each was released after blood feeding from ventricular axons that terminate on the anterior midgut. A subset of ILP family members and OEH stimulated nutrient storage in previtellogenic females before blood feeding, whereas most IIS-dependent processes after blood feeding were activated by one or more of the brain-specific ILPs and/or OEH. ILPs and OEH with different biological activities also exhibited differences in IIS as measured by phosphorylation of the IR, phosphoinositide 3-kinase/Akt kinase (AKT) and mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK). Altogether, our results provide the first results that compare the functional activities of all ILP family members and OEH produced by an insect.
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Affiliation(s)
- Kangkang Chen
- Department of Entomology, University of Georgia, Athens, GA, USA
| | - Xiaoyi Dou
- Department of Entomology, University of Georgia, Athens, GA, USA
| | - Jai Hoon Eum
- Department of Entomology, University of Georgia, Athens, GA, USA
| | - Ruby E Harrison
- Department of Entomology, University of Georgia, Athens, GA, USA
| | - Mark R Brown
- Department of Entomology, University of Georgia, Athens, GA, USA.
| | - Michael R Strand
- Department of Entomology, University of Georgia, Athens, GA, USA.
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Harrison RE, Yang X, Eum JH, Martinson VG, Dou X, Valzania L, Wang Y, Boyd BM, Brown MR, Strand MR. The mosquito Aedes aegypti requires a gut microbiota for normal fecundity, longevity and vector competence. Commun Biol 2023; 6:1154. [PMID: 37957247 PMCID: PMC10643675 DOI: 10.1038/s42003-023-05545-z] [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: 01/09/2023] [Accepted: 11/03/2023] [Indexed: 11/15/2023] Open
Abstract
Mosquitoes shift from detritus-feeding larvae to blood-feeding adults that can vector pathogens to humans and other vertebrates. The sugar and blood meals adults consume are rich in carbohydrates and protein but are deficient in other nutrients including B vitamins. Facultatively hematophagous insects like mosquitoes have been hypothesized to avoid B vitamin deficiencies by carryover of resources from the larval stage. However, prior experimental studies have also used adults with a gut microbiota that could provision B vitamins. Here, we used Aedes aegypti, which is the primary vector of dengue virus (DENV), to ask if carryover effects enable normal function in adults with no microbiota. We show that adults with no gut microbiota produce fewer eggs, live longer with lower metabolic rates, and exhibit reduced DENV vector competence but are rescued by provisioning B vitamins or recolonizing the gut with B vitamin autotrophs. We conclude carryover effects do not enable normal function.
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Affiliation(s)
- Ruby E Harrison
- Department of Entomology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
- Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Xiushuai Yang
- Department of Entomology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Jai Hoon Eum
- Department of Entomology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Vincent G Martinson
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Xiaoyi Dou
- Department of Entomology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Luca Valzania
- Institut Curie, 20 Rue d'Ulm, 75238, Paris, Cedex 05, France
| | - Yin Wang
- Department of Entomology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Bret M Boyd
- Center for Biological Data Science, Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Mark R Brown
- Department of Entomology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Michael R Strand
- Department of Entomology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.
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Dou X, Chen K, Brown MR, Strand MR. Multiple endocrine factors regulate nutrient mobilization and storage in Aedes aegypti during a gonadotrophic cycle. INSECT SCIENCE 2023; 30:425-442. [PMID: 36056560 DOI: 10.1111/1744-7917.13110] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/20/2022] [Accepted: 08/22/2022] [Indexed: 06/15/2023]
Abstract
Anautogenous mosquitoes must blood feed on a vertebrate host to produce eggs. Each gonadotrophic cycle is subdivided into a sugar-feeding previtellogenic phase that produces primary follicles and a blood meal-activated vitellogenic phase in which large numbers of eggs synchronously mature and are laid. Multiple endocrine factors including juvenile hormone (JH), insulin-like peptides (ILPs), ovary ecdysteroidogenic hormone (OEH), and 20-hydroxyecdysone (20E) coordinate each gonadotrophic cycle. Egg formation also requires nutrients from feeding that are stored in the fat body. Regulation of egg formation is best understood in Aedes aegypti but the role different endocrine factors play in regulating nutrient mobilization and storage remains unclear. In this study, we report that adult female Ae. aegypti maintained triacylglycerol (TAG) stores during the previtellogenic phase of the first gonadotrophic cycle while glycogen stores declined. In contrast, TAG and glycogen stores were rapidly mobilized during the vitellogenic phase and then replenishment. Several genes encoding enzymes with functions in TAG and glycogen metabolism were differentially expressed in the fat body, which suggested regulation was mediated in part at the transcriptional level. Gain of function assays indicated that stored nutrients were primarily mobilized by adipokinetic hormone (AKH) while juvenoids and OEH regulated replenishment. ILP3 further showed evidence of negatively regulating certain lipolytic enzymes. Loss of function assays indicated AKH depends on the AKH receptor (AKHR) for function. Altogether, our results indicate that the opposing activities of different hormones regulate nutrient stores during a gonadotrophic cycle in Ae. aegypti.
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Affiliation(s)
- Xiaoyi Dou
- Department of Entomology, University of Georgia, Athens, Georgia, 30602, United States
| | - Kangkang Chen
- Department of Entomology, University of Georgia, Athens, Georgia, 30602, United States
- Department of Plant Protection, College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, Jiangsu Province, China
| | - Mark R Brown
- Department of Entomology, University of Georgia, Athens, Georgia, 30602, United States
| | - Michael R Strand
- Department of Entomology, University of Georgia, Athens, Georgia, 30602, United States
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