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CCHamide-2 Signaling Regulates Food Intake and Metabolism in Gryllus bimaculatus. INSECTS 2022; 13:insects13040324. [PMID: 35447766 PMCID: PMC9026500 DOI: 10.3390/insects13040324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 03/09/2022] [Accepted: 03/23/2022] [Indexed: 12/14/2022]
Abstract
Neuropeptides play vital roles in energy homeostasis in insects and other animals. Although the importance of the regulatory network of neuropeptides in feeding and metabolism has been illuminated, a complete understanding of the mechanisms has not been addressed as many factors are involved in the regulation. CCHamide-2 is a newly identified brain-gut neuropeptide that regulates feeding behavior in several insect species including Drosophila melanogaster. However, little is known about the mechanisms controlling the feeding-related behavior and metabolic functions modulated by CCHamide-2 in other insects. In this study, we addressed the functions of CCHamide-2 in the two-spotted cricket, Gryllus bimaculatus, which was used as the experimental material to research the mechanisms of feeding and metabolism in this omnivorous insect species. Knockdown crickets by RNA interference against GbCCHamide-2R increased the amount of food intake, while injection of chemically synthetic GbCCHamide-2 peptide reduced the amount of food intake. Further, knockdown and peptide injection experiments revealed that GbCCHamide-2 signaling increased the concentrations of circulating lipids and carbohydrates, and the carbohydrate-rich diet increased the transcript levels of GbCCHa-2R. Moreover, GbCCHa-2 injection decreased the transcript level of Gbilp. By contrast, GbCCHamide-2 signaling did not affect nymphal growth or the transcript level of GbAKH, as well as feeding preferences. Taken together, CCHamide-2 signaling in G. bimaculatus regulates food intake associated with alterations in lipid and carbohydrate levels in hemolymph.
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2
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Excessive energy expenditure due to acute physical restraint disrupts Drosophila motivational feeding response. Sci Rep 2021; 11:24208. [PMID: 34921197 PMCID: PMC8683507 DOI: 10.1038/s41598-021-03575-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 12/03/2021] [Indexed: 11/22/2022] Open
Abstract
To study the behavior of Drosophila, it is often necessary to restrain and mount individual flies. This requires removal from food, additional handling, anesthesia, and physical restraint. We find a strong positive correlation between the length of time flies are mounted and their subsequent reflexive feeding response, where one hour of mounting is the approximate motivational equivalent to ten hours of fasting. In an attempt to explain this correlation, we rule out anesthesia side-effects, handling, additional fasting, and desiccation. We use respirometric and metabolic techniques coupled with behavioral video scoring to assess energy expenditure in mounted and free flies. We isolate a specific behavior capable of exerting large amounts of energy in mounted flies and identify it as an attempt to escape from restraint. We present a model where physical restraint leads to elevated activity and subsequent faster nutrient storage depletion among mounted flies. This ultimately further accelerates starvation and thus increases reflexive feeding response. In addition, we show that the consequences of the physical restraint profoundly alter aerobic activity, energy depletion, taste, and feeding behavior, and suggest that careful consideration is given to the time-sensitive nature of these highly significant effects when conducting behavioral, physiological or imaging experiments that require immobilization.
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3
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Glial glucose fuels the neuronal pentose phosphate pathway for long-term memory. Cell Rep 2021; 36:109620. [PMID: 34433052 PMCID: PMC8411112 DOI: 10.1016/j.celrep.2021.109620] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 07/22/2021] [Accepted: 08/05/2021] [Indexed: 01/10/2023] Open
Abstract
Brain function relies almost solely on glucose as an energy substrate. The main model of brain metabolism proposes that glucose is taken up and converted into lactate by astrocytes to fuel the energy-demanding neuronal activity underlying plasticity and memory. Whether direct neuronal glucose uptake is required for memory formation remains elusive. We uncover, in Drosophila, a mechanism of glucose shuttling to neurons from cortex glia, an exclusively perisomatic glial subtype, upon formation of olfactory long-term memory (LTM). In vivo imaging reveals that, downstream of cholinergic activation of cortex glia, autocrine insulin signaling increases glucose concentration in glia. Glucose is then transferred from glia to the neuronal somata in the olfactory memory center to fuel the pentose phosphate pathway and allow LTM formation. In contrast, our results indicate that the increase in neuronal glucose metabolism, although crucial for LTM formation, is not routed to glycolysis. Neuronal glucose metabolism is increased upon long-term memory formation Glial cells shuttle glucose to neurons following insulin signaling activation Glucose fuels the neuronal pentose phosphate pathway
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4
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Yu J, Yang W, Lin T, Zeng X, Liu J. Unequal rewarding of three metabolizable sugars - sucrose, fructose and glucose - in olfactory learning and memory in Bactrocera dorsalis. J Exp Biol 2020; 223:jeb225219. [PMID: 32709628 DOI: 10.1242/jeb.225219] [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: 03/16/2020] [Accepted: 07/20/2020] [Indexed: 11/20/2022]
Abstract
Learning and memory are the most characterized advanced neurological activities of insects, which can associate information with food. Our previous studies on Bactrocera dorsalis have shown that this fly can learn to evaluate the nutritional value of sugar rewards, although whether all metabolizable sugars are equally rewarding to flies is still unclear. To address this question, we used three sweet and metabolizable sugars - sucrose, fructose and glucose - as rewards for conditioning. The flies showed differences in learning and memory in response to the three sugar rewards. The level of learning performance in sucrose-rewarded flies was higher than that in fructose-rewarded and glucose-rewarded flies, and, strikingly, only sucrose and glucose stimulation led to the formation of robust 24-h memory. Furthermore, the unequal rewarding of three sugars was observed in two distinct processes of memory formation: preingestive and postingestive processes. When flies received the positive tastes (preingestive signal) by touching their tarsi and proboscis (mouthparts) to three sugars, they showed differences in learning for the three sugar rewards. The formation of a robust 24-h memory was dependent on the postingestive signal triggered by feeding on a sugar. A deficit of 24-h memory was observed only in fructose-feeding flies no matter what sugar was used to stimulate the tarsi. Taken together, our results suggest that three sweet and metabolizable sugars unequally rewarded B. dorsalis, which might be a strategy for flies to discriminate the nature of sugars.
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Affiliation(s)
- Jinxin Yu
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Agriculture, Department of Pesticide Science, South China Agricultural University, Guangzhou, Guangdong, China 510642
| | - Weiping Yang
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Agriculture, Department of Pesticide Science, South China Agricultural University, Guangzhou, Guangdong, China 510642
| | - Tao Lin
- College of Life Sciences, Department of Biological Science, Shangrao Normal University, Jiangxi, China 334001
| | - Xinnian Zeng
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Agriculture, Department of Pesticide Science, South China Agricultural University, Guangzhou, Guangdong, China 510642
| | - Jiali Liu
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Agriculture, Department of Pesticide Science, South China Agricultural University, Guangzhou, Guangdong, China 510642
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5
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Brünner B, Saumweber J, Samur M, Weber D, Schumann I, Mahishi D, Rohwedder A, Thum AS. Food restriction reconfigures naïve and learned choice behavior in Drosophila larvae. J Neurogenet 2020; 34:123-132. [PMID: 31975653 DOI: 10.1080/01677063.2020.1714612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
In many animals, the establishment and expression of food-related memory is limited by the presence of food and promoted by its absence, implying that this behavior is driven by motivation. In the past, this has already been demonstrated in various insects including honeybees and adult Drosophila. For Drosophila larvae, which are characterized by an immense growth and the resulting need for constant food intake, however, knowledge is rather limited. Accordingly, we have analyzed whether starvation modulates larval memory formation or expression after appetitive classical olfactory conditioning, in which an odor is associated with a sugar reward. We show that odor-sugar memory of starved larvae lasts longer than in fed larvae, although the initial performance is comparable. 80 minutes after odor fructose conditioning, only starved but not fed larvae show a reliable odor-fructose memory. This is likely due to a specific increase in the stability of anesthesia-resistant memory (ARM). Furthermore, we observe that starved larvae, in contrast to fed ones, prefer sugars that offer a nutritional benefit in addition to their sweetness. Taken together our work shows that Drosophila larvae adjust the expression of learned and naïve choice behaviors in the absence of food. These effects are only short-lasting probably due to their lifestyle and their higher internal motivation to feed. In the future, the extensive use of established genetic tools will allow us to identify development-specific differences arising at the neuronal and molecular level.
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Affiliation(s)
- Benita Brünner
- Department of Genetics, University of Leipzig, Leipzig, Germany
| | | | - Merve Samur
- Department of Genetics, University of Leipzig, Leipzig, Germany.,Faculty of Engineering and Natural Sciences, Üsküdar University, Istanbul, Turkey
| | - Denise Weber
- Department of Genetics, University of Leipzig, Leipzig, Germany
| | | | - Deepthi Mahishi
- Department of Genetics, University of Leipzig, Leipzig, Germany
| | | | - Andreas S Thum
- Department of Genetics, University of Leipzig, Leipzig, Germany
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6
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Toshima N, Kantar Weigelt M, Weiglein A, Boetzl FA, Gerber B. An amino-acid mixture can be both rewarding and punishing to larval Drosophila melanogaster. ACTA ACUST UNITED AC 2019; 222:jeb.209486. [PMID: 31672727 DOI: 10.1242/jeb.209486] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 10/24/2019] [Indexed: 12/17/2022]
Abstract
Amino acids are important nutrients for animals because they are necessary for protein synthesis in particular during growth, as well as for neurotransmission. However, little is known about how animals use past experience to guide their search for amino-acid-rich food. We reasoned that the larvae of Drosophila melanogaster are suitable for investigating this topic because they are the feeding and growth stages in the life cycle of these holometabolous insects. Specifically, we investigated whether experiencing an odour with a 20 amino-acid mixture as a semi-natural tastant during training establishes odour-tastant associative memories. Across a broad concentration range (0.01-20 mmol l-1), such an amino-acid mixture was found to have a rewarding effect, establishing appetitive memory for the odour. To our surprise, however, manipulation of the test conditions revealed that relatively high concentrations of the amino-acid mixture (3.3 mmol l-1 and higher) in addition establish aversive memory for the odour. We then characterized both of these oppositely valenced memories in terms of their dependency on the number of training trials, their temporal stability, their modulation through starvation and the specific changes in locomotion underlying them. Collectively, and in the light of what is known about the neuronal organization of odour-food memory in larval D . melanogaster, our data suggest that these memories are established in parallel. We discuss the similarity of our results to what has been reported for sodium chloride, and the possible neurogenetic bases for concentration-dependent changes in valence when these tastants are used as reinforcers.
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Affiliation(s)
- Naoko Toshima
- Department Genetics of Learning and Memory, Leibniz Institute for Neurobiology (LIN), Brenneckestrasse 6, 39118 Magdeburg, Germany
| | - Melisa Kantar Weigelt
- Department Genetics of Learning and Memory, Leibniz Institute for Neurobiology (LIN), Brenneckestrasse 6, 39118 Magdeburg, Germany
| | - Aliće Weiglein
- Department Genetics of Learning and Memory, Leibniz Institute for Neurobiology (LIN), Brenneckestrasse 6, 39118 Magdeburg, Germany
| | - Fabian A Boetzl
- Department of Animal Ecology and Tropical Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Bertram Gerber
- Department Genetics of Learning and Memory, Leibniz Institute for Neurobiology (LIN), Brenneckestrasse 6, 39118 Magdeburg, Germany.,Institute for Biology, Otto von Guericke University Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), 39106 Magdeburg, Germany
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7
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Yu J, Yang W, Zeng X, Liu J. The oriental fruit fly Bactrocera dorsalis learns and remembers sugar quality. JOURNAL OF INSECT PHYSIOLOGY 2019; 117:103895. [PMID: 31185201 DOI: 10.1016/j.jinsphys.2019.103895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 06/06/2019] [Accepted: 06/07/2019] [Indexed: 06/09/2023]
Abstract
The oriental fruit fly Bactrocera dorsalis can learn to associate an odor with a sugar reward. However, it is still unclear whether they will learn with different sugar rewards equally. Here, we used a proboscis extension conditioning procedure to investigate the contribution of taste and nutritional value of sugars to learning and memory formation. Three types of sugar were used for conditioning: sweet and nutritional sugar, sucrose; sweet sugar without nutrition, D-arabinose and L-glucose; tasteless sugar with nutritional value, D-sorbitol. The sweet taste is sufficient to produce associative conditioning with an odor and form short-term memory, and the learning and short-term memory performance showed a similar rank order to the proboscis extension reflex evoked by each sugar. However, memory decayed at a greater rate 24 h after conditioning for flies conditioned with sweet tasting but non-metabolizable sugars D-arabinose and L-glucose. When D-arabinose or L-glucose was supplemented with D-sorbitol, the deficit of 24 h memory was rescued, suggesting that the nutrient value of sugar plays a key role in memory persistence. Our results indicate that B. dorsalis could learn and evaluate sugar quality via both taste and nutritional value, as well as remember nutrient sugars for a long time using a postingestive mechanism.
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Affiliation(s)
- Jinxin Yu
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Agriculture, South China Agricultural University, Guangzhou, Guangdong, China
| | - Weiping Yang
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Agriculture, South China Agricultural University, Guangzhou, Guangdong, China
| | - Xinnian Zeng
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Agriculture, South China Agricultural University, Guangzhou, Guangdong, China.
| | - Jiali Liu
- Guangdong Engineering Research Center for Insect Behavior Regulation, College of Agriculture, South China Agricultural University, Guangzhou, Guangdong, China.
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8
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Ugrankar R, Theodoropoulos P, Akdemir F, Henne WM, Graff JM. Circulating glucose levels inversely correlate with Drosophila larval feeding through insulin signaling and SLC5A11. Commun Biol 2018; 1:110. [PMID: 30271990 PMCID: PMC6123810 DOI: 10.1038/s42003-018-0109-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 07/03/2018] [Indexed: 12/27/2022] Open
Abstract
In mammals, blood glucose levels likely play a role in appetite regulation yet the mechanisms underlying this phenomenon remain opaque. Mechanisms can often be explored from Drosophila genetic approaches. To determine if circulating sugars might be involved in Drosophila feeding behaviors, we scored hemolymph glucose and trehalose, and food ingestion in larvae subjected to various diets, genetic mutations, or RNAi. We found that larvae with glucose elevations, hyperglycemia, have an aversion to feeding; however, trehalose levels do not track with feeding behavior. We further discovered that insulins and SLC5A11 may participate in glucose-regulated feeding. To see if food aversion might be an appropriate screening method for hyperglycemia candidates, we developed a food aversion screen to score larvae with abnormal feeding for glucose. We found that many feeding defective larvae have glucose elevations. These findings highlight intriguing roles for glucose in fly biology as a potential cue and regulator of appetite. Rupali Ugrankar et al. show that Drosophila larvae with high levels of circulating glucose, but not trehalose, don’t eat much. This study suggests that circulating glucose communicates with insulin signaling and the sodium/solute co-transporter SLC5A11 in the brain to suppress larval appetite.
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Affiliation(s)
- Rupali Ugrankar
- Department of Developmental Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA. .,Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA.
| | - Pano Theodoropoulos
- Department of Developmental Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA
| | - Fatih Akdemir
- Department of Developmental Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA.,Department of Basic Sciences, Medical Biology, Ataturk University, 25240 Erzurum, Turkey
| | - W Mike Henne
- Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA
| | - Jonathan M Graff
- Department of Developmental Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA. .,Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA. .,Department of Internal Medicine, Division of Endocrinology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA.
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9
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König C, Khalili A, Ganesan M, Nishu AP, Garza AP, Niewalda T, Gerber B, Aso Y, Yarali A. Reinforcement signaling of punishment versus relief in fruit flies. ACTA ACUST UNITED AC 2018; 25:247-257. [PMID: 29764970 PMCID: PMC5959229 DOI: 10.1101/lm.047308.118] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 04/06/2018] [Indexed: 01/21/2023]
Abstract
Painful events establish opponent memories: cues that precede pain are remembered negatively, whereas cues that follow pain, thus coinciding with relief are recalled positively. How do individual reinforcement-signaling neurons contribute to this “timing-dependent valence-reversal?” We addressed this question using an optogenetic approach in the fruit fly. Two types of fly dopaminergic neuron, each comprising just one paired cell, indeed established learned avoidance of odors that preceded their photostimulation during training, and learned approach to odors that followed the photostimulation. This is in striking parallel to punishment versus relief memories reinforced by a real noxious event. For only one of these neuron types, both effects were strong enough for further analyses. Notably, interfering with dopamine biosynthesis in these neurons partially impaired the punishing effect, but not the relieving after-effect of their photostimulation. We discuss how this finding constraints existing computational models of punishment versus relief memories and introduce a new model, which also incorporates findings from mammals. Furthermore, whether using dopaminergic neuron photostimulation or a real noxious event, more prolonged punishment led to stronger relief. This parametric feature of relief may also apply to other animals and may explain particular aspects of related behavioral dysfunction in humans.
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Affiliation(s)
- Christian König
- Leibniz Institute for Neurobiology, Research Group Molecular Systems Biology of Learning, Magdeburg 39118, Germany.,Institute of Pharmacology and Toxicology, Otto von Guericke University Magdeburg 39118, Germany
| | - Afshin Khalili
- Leibniz Institute for Neurobiology, Research Group Molecular Systems Biology of Learning, Magdeburg 39118, Germany
| | - Mathangi Ganesan
- Leibniz Institute for Neurobiology, Research Group Molecular Systems Biology of Learning, Magdeburg 39118, Germany
| | - Amrita P Nishu
- Leibniz Institute for Neurobiology, Research Group Molecular Systems Biology of Learning, Magdeburg 39118, Germany
| | - Alejandra P Garza
- Leibniz Institute for Neurobiology, Research Group Molecular Systems Biology of Learning, Magdeburg 39118, Germany
| | - Thomas Niewalda
- Leibniz Institute for Neurobiology, Department Genetics of Learning and Memory, Magdeburg 39118, Germany
| | - Bertram Gerber
- Leibniz Institute for Neurobiology, Department Genetics of Learning and Memory, Magdeburg 39118, Germany.,Otto von Guericke University, Institute for Biology, Behavioural Genetics, Magdeburg 39118, Germany.,Center for Behavioral Brain Sciences, Magdeburg 39118, Germany
| | - Yoshinori Aso
- HHMI, Janelia Research Campus, Ashburn, Virginia 20147, USA
| | - Ayse Yarali
- Leibniz Institute for Neurobiology, Research Group Molecular Systems Biology of Learning, Magdeburg 39118, Germany.,Center for Behavioral Brain Sciences, Magdeburg 39118, Germany
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10
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Ryvkin J, Bentzur A, Zer-Krispil S, Shohat-Ophir G. Mechanisms Underlying the Risk to Develop Drug Addiction, Insights From Studies in Drosophila melanogaster. Front Physiol 2018; 9:327. [PMID: 29740329 PMCID: PMC5928757 DOI: 10.3389/fphys.2018.00327] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Accepted: 03/15/2018] [Indexed: 12/21/2022] Open
Abstract
The ability to adapt to environmental changes is an essential feature of biological systems, achieved in animals by a coordinated crosstalk between neuronal and hormonal programs that allow rapid and integrated organismal responses. Reward systems play a key role in mediating this adaptation by reinforcing behaviors that enhance immediate survival, such as eating or drinking, or those that ensure long-term survival, such as sexual behavior or caring for offspring. Drugs of abuse co-opt neuronal and molecular pathways that mediate natural rewards, which under certain circumstances can lead to addiction. Many factors can contribute to the transition from drug use to drug addiction, highlighting the need to discover mechanisms underlying the progression from initial drug use to drug addiction. Since similar responses to natural and drug rewards are present in very different animals, it is likely that the central systems that process reward stimuli originated early in evolution, and that common ancient biological principles and genes are involved in these processes. Thus, the neurobiology of natural and drug rewards can be studied using simpler model organisms that have their systems stripped of some of the immense complexity that exists in mammalian brains. In this paper we review studies in Drosophila melanogaster that model different aspects of natural and drug rewards, with an emphasis on how motivational states shape the value of the rewarding experience, as an entry point to understanding the mechanisms that contribute to the vulnerability of drug addiction.
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Affiliation(s)
- Julia Ryvkin
- The Mina & Everard Goodman Faculty of Life Sciences and The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
| | - Assa Bentzur
- The Mina & Everard Goodman Faculty of Life Sciences and The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
| | - Shir Zer-Krispil
- The Mina & Everard Goodman Faculty of Life Sciences and The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
| | - Galit Shohat-Ophir
- The Mina & Everard Goodman Faculty of Life Sciences and The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
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11
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Widmann A, Eichler K, Selcho M, Thum AS, Pauls D. Odor-taste learning in Drosophila larvae. JOURNAL OF INSECT PHYSIOLOGY 2018; 106:47-54. [PMID: 28823531 DOI: 10.1016/j.jinsphys.2017.08.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 08/07/2017] [Accepted: 08/16/2017] [Indexed: 06/07/2023]
Abstract
The Drosophila larva is an attractive model system to study fundamental questions in the field of neuroscience. Like the adult fly, the larva offers a seemingly unlimited genetic toolbox, which allows one to visualize, silence or activate neurons down to the single cell level. This, combined with its simplicity in terms of cell numbers, offers a useful system to study the neuronal correlates of complex processes including associative odor-taste learning and memory formation. Here, we summarize the current knowledge about odor-taste learning and memory at the behavioral level and integrate the recent progress on the larval connectome to shed light on the sub-circuits that allow Drosophila larvae to integrate present sensory input in the context of past experience and to elicit an appropriate behavioral response.
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Affiliation(s)
| | - Katharina Eichler
- Department of Biology, University of Konstanz, D-78464 Konstanz, Germany; HHMI Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Mareike Selcho
- Department of Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, University of Würzburg, D-97074 Würzburg, Germany
| | - Andreas S Thum
- Department of Biology, University of Konstanz, D-78464 Konstanz, Germany; Department of Genetics, University of Leipzig, D-04103 Leipzig, Germany.
| | - Dennis Pauls
- Department of Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, University of Würzburg, D-97074 Würzburg, Germany.
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12
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Abstract
Excess adipose fat accumulation, or obesity, is a growing problem worldwide in terms of both the rate of incidence and the severity of obesity-associated metabolic disease. Adipose tissue evolved in animals as a specialized dynamic lipid storage depot: adipose cells synthesize fat (a process called lipogenesis) when energy is plentiful and mobilize stored fat (a process called lipolysis) when energy is needed. When a disruption of lipid homeostasis favors increased fat synthesis and storage with little turnover owing to genetic predisposition, overnutrition or sedentary living, complications such as diabetes and cardiovascular disease are more likely to arise. The vinegar fly Drosophila melanogaster (Diptera: Drosophilidae) is used as a model to better understand the mechanisms governing fat metabolism and distribution. Flies offer a wealth of paradigms with which to study the regulation and physiological effects of fat accumulation. Obese flies accumulate triacylglycerols in the fat body, an organ similar to mammalian adipose tissue, which specializes in lipid storage and catabolism. Discoveries in Drosophila have ranged from endocrine hormones that control obesity to subcellular mechanisms that regulate lipogenesis and lipolysis, many of which are evolutionarily conserved. Furthermore, obese flies exhibit pathophysiological complications, including hyperglycemia, reduced longevity and cardiovascular function - similar to those observed in obese humans. Here, we review some of the salient features of the fly that enable researchers to study the contributions of feeding, absorption, distribution and the metabolism of lipids to systemic physiology.
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Affiliation(s)
- Laura Palanker Musselman
- Department of Biological Sciences, Binghamton University, State University of New York, Binghamton, NY 13902, USA
| | - Ronald P Kühnlein
- Department of Biochemistry 1, Institute of Molecular Biosciences, University of Graz, Humboldtstraβe 50/II, A-8010 Graz, Austria.,BioTechMed-Graz, Graz, Austria
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13
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Ichinose T, Tanimoto H, Yamagata N. Behavioral Modulation by Spontaneous Activity of Dopamine Neurons. Front Syst Neurosci 2017; 11:88. [PMID: 29321731 PMCID: PMC5732226 DOI: 10.3389/fnsys.2017.00088] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 11/14/2017] [Indexed: 01/11/2023] Open
Abstract
Dopamine modulates a variety of animal behaviors that range from sleep and learning to courtship and aggression. Besides its well-known phasic firing to natural reward, a substantial number of dopamine neurons (DANs) are known to exhibit ongoing intrinsic activity in the absence of an external stimulus. While accumulating evidence points at functional implications for these intrinsic "spontaneous activities" of DANs in cognitive processes, a causal link to behavior and its underlying mechanisms has yet to be elucidated. Recent physiological studies in the model organism Drosophila melanogaster have uncovered that DANs in the fly brain are also spontaneously active, and that this activity reflects the behavioral/internal states of the animal. Strikingly, genetic manipulation of basal DAN activity resulted in behavioral alterations in the fly, providing critical evidence that links spontaneous DAN activity to behavioral states. Furthermore, circuit-level analyses have started to reveal cellular and molecular mechanisms that mediate or regulate spontaneous DAN activity. Through reviewing recent findings in different animals with the major focus on flies, we will discuss potential roles of this physiological phenomenon in directing animal behaviors.
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Affiliation(s)
- Toshiharu Ichinose
- Graduate School of Life Sciences, Tohoku University, Sendai, Japan.,Department of Neuroscience of Disease, Center for Transdisciplinary Research, Niigata University, Niigata, Japan
| | - Hiromu Tanimoto
- Graduate School of Life Sciences, Tohoku University, Sendai, Japan
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14
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Murata S, Brockmann A, Tanimura T. Pharyngeal stimulation with sugar triggers local searching behavior in Drosophila. ACTA ACUST UNITED AC 2017; 220:3231-3237. [PMID: 28684466 DOI: 10.1242/jeb.161646] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Accepted: 06/29/2017] [Indexed: 10/19/2022]
Abstract
Foraging behavior is essential for all organisms to find food containing nutritional chemicals. A hungry Drosophila melanogaster fly performs local searching behavior after drinking a small amount of sugar solution. Using video tracking, we examined how the searching behavior is regulated in D. melanogaster We found that a small amount of highly concentrated sugar solution induced a long-lasting searching behavior. After the intake of sugar solution, a fly moved around in circles and repeatedly returned to the position where the sugar droplet had been placed. The non-nutritious sugar d-arabinose, but not the non-sweet nutritious sugar d-sorbitol, was effective in inducing the behavior, indicating that sweet sensation is essential. Furthermore, pox-neuro mutant flies, which have no external taste bristles, showed local searching behavior, suggesting the involvement of the pharyngeal taste organ. Experimental activation of pharyngeal sugar-sensitive gustatory receptor neurons by capsaicin using the GAL4/UAS system induced local searching behavior. In contrast, inhibition of pharyngeal sugar-responsive gustatory receptor neurons abolished the searching behavior. Together, our results indicate that, in Drosophila, the pharyngeal taste-receptor neurons trigger searching behavior immediately after ingestion.
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Affiliation(s)
- Satoshi Murata
- Graduate School of Systems Life Sciences, Kyushu University, Motooka 744, Fukuoka, 819-0395, Japan
| | - Axel Brockmann
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560056, India
| | - Teiichi Tanimura
- Graduate School of Systems Life Sciences, Kyushu University, Motooka 744, Fukuoka, 819-0395, Japan .,Department of Biology, Faculty of Science, Kyushu University, Motooka 744, Fukuoka, 819-0395, Japan
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15
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Kannan R, Giniger E. New perspectives on the roles of Abl tyrosine kinase in axon patterning. Fly (Austin) 2017; 11:260-270. [PMID: 28481649 DOI: 10.1080/19336934.2017.1327106] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
The Abelson tyrosine kinase (Abl) lies at the heart of one of the small set of ubiquitous, conserved signal transduction pathways that do much of the work of development and physiology. Abl signaling is essential to epithelial integrity, motility of autonomous cells such as blood cells, and axon growth and guidance in the nervous system. However, though Abl was one of the first of these conserved signaling machines to be identified, it has been among the last to have its essential architecture elucidated. Here we will first discuss some of the challenges that long delayed the dissection of this pathway, and what they tell us about the special problems of investigating dynamic processes like motility. We will then describe our recent experiments that revealed the functional organization of the Abl pathway in Drosophila neurons. Finally, in the second part of the review we will introduce a different kind of complexity in the role of Abl in motility: the discovery of a previously unappreciated function in protein secretion and trafficking. We will provide evidence that the secretory function of Abl also contributes to its role in axon growth and guidance, and finally end with a discussion of the challenges that Abl pleiotropy provide for the investigator, but the opportunities that it provides for coordinating biological regulation.
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Affiliation(s)
- Ramakrishnan Kannan
- a Neurobiology Research Center (NRC), Department of Psychiatry , National Institute of Mental Health and Neurosciences , Bangalore , India
| | - Edward Giniger
- b National Institute of Neurological Disorders and Stroke, National Institutes of Health , Bethesda , MD
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16
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Landayan D, Wolf FW. Shared neurocircuitry underlying feeding and drugs of abuse in Drosophila. Biomed J 2016; 38:496-509. [PMID: 27013449 PMCID: PMC6138758 DOI: 10.1016/j.bj.2016.01.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 06/13/2015] [Indexed: 01/06/2023] Open
Abstract
The neural circuitry and molecules that control the rewarding properties of food and drugs of abuse appear to partially overlap in the mammalian brain. This has raised questions about the extent of the overlap and the precise role of specific circuit elements in reward and in other behaviors associated with feeding regulation and drug responses. The much simpler brain of invertebrates including the fruit fly Drosophila, offers an opportunity to make high-resolution maps of the circuits and molecules that govern behavior. Recent progress in Drosophila has revealed not only some common substrates for the actions of drugs of abuse and for the regulation of feeding, but also a remarkable level of conservation with vertebrates for key neuromodulatory transmitters. We speculate that Drosophila may serve as a model for distinguishing the neural mechanisms underlying normal and pathological motivational states that will be applicable to mammals.
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Affiliation(s)
- Dan Landayan
- Department of Molecular Cell Biology, School of Natural Sciences, University of California, Merced, CA, USA.
| | - Fred W Wolf
- Department of Molecular Cell Biology, School of Natural Sciences, University of California, Merced, CA, USA.
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17
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Das G, Lin S, Waddell S. Remembering Components of Food in Drosophila. Front Integr Neurosci 2016; 10:4. [PMID: 26924969 PMCID: PMC4759284 DOI: 10.3389/fnint.2016.00004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 01/25/2016] [Indexed: 12/28/2022] Open
Abstract
Remembering features of past feeding experience can refine foraging and food choice. Insects can learn to associate sensory cues with components of food, such as sugars, amino acids, water, salt, alcohol, toxins and pathogens. In the fruit fly Drosophila some food components activate unique subsets of dopaminergic neurons (DANs) that innervate distinct functional zones on the mushroom bodies (MBs). This architecture suggests that the overall dopaminergic neuron population could provide a potential cellular substrate through which the fly might learn to value a variety of food components. In addition, such an arrangement predicts that individual component memories reside in unique locations. DANs are also critical for food memory consolidation and deprivation-state dependent motivational control of the expression of food-relevant memories. Here, we review our current knowledge of how nutrient-specific memories are formed, consolidated and specifically retrieved in insects, with a particular emphasis on Drosophila.
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Affiliation(s)
- Gaurav Das
- Centre for Neural Circuits and Behaviour, University of OxfordOxford, UK
| | - Suewei Lin
- Centre for Neural Circuits and Behaviour, University of OxfordOxford, UK
| | - Scott Waddell
- Centre for Neural Circuits and Behaviour, University of OxfordOxford, UK
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18
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ICHINOSE T, TANIMOTO H. Dynamics of memory-guided choice behavior in Drosophila. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2016; 92:346-357. [PMID: 27725473 PMCID: PMC5243950 DOI: 10.2183/pjab.92.346] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 07/25/2016] [Indexed: 06/06/2023]
Abstract
Memory retrieval requires both accuracy and speed. Olfactory learning of the fruit fly Drosophila melanogaster serves as a powerful model system to identify molecular and neuronal substrates of memory and memory-guided behavior. The behavioral expression of olfactory memory has traditionally been tested as a conditioned odor response in a simple T-maze, which measures the result, but not the speed, of odor choice. Here, we developed multiplexed T-mazes that allow video recording of the choice behavior. Automatic fly counting in each arm of the maze visualizes choice dynamics. Using this setup, we show that the transient blockade of serotonergic neurons slows down the choice, while leaving the eventual choice intact. In contrast, activation of the same neurons impairs the eventual performance leaving the choice speed unchanged. Our new apparatus contributes to elucidating how the speed and the accuracy of memory retrieval are implemented in the fly brain.
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Affiliation(s)
- Toshiharu ICHINOSE
- Tohoku University Graduate School of Life Sciences, Sendai, Japan
- Max-Planck Institut für Neurobiologie, Martinsried, Germany
| | - Hiromu TANIMOTO
- Tohoku University Graduate School of Life Sciences, Sendai, Japan
- Max-Planck Institut für Neurobiologie, Martinsried, Germany
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19
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Maeda T, Tamotsu M, Yamaoka R, Ozaki M. Effects of Floral Scents and Their Dietary Experiences on the Feeding Preference in the Blowfly, Phormia regina. Front Integr Neurosci 2015; 9:59. [PMID: 26648851 PMCID: PMC4664696 DOI: 10.3389/fnint.2015.00059] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 11/09/2015] [Indexed: 11/26/2022] Open
Abstract
The flowers of different plant species have diverse scents with varied chemical compositions. Hence, every floral scent does not uniformly affect insect feeding preferences. The blowfly, Phormia regina, is a nectar feeder, and when a fly feeds on flower nectar, its olfactory organs, antennae, and maxillary palps are exposed to the scent. Generally, feeding preference is influenced by food flavor, which relies on both taste and odor. Therefore, the flies perceive the sweet taste of nectar and the particular scent of the flower simultaneously, and this olfactory information affects their feeding preference. Here, we show that the floral scents of 50 plant species have various effects on their sucrose feeding motivation, which was evaluated using the proboscis extension reflex (PER). Those floral scents were first categorized into three groups, based on their effects on the PER threshold sucrose concentration, which indicates whether a fly innately dislikes, ignores, or likes the target scent. Moreover, memory of olfactory experience with those floral scents during sugar feeding influenced the PER threshold. After feeding on sucrose solutions flavored with floral scents for 5 days, the scents did not consistently show the previously observed effects. Considering such empirical effects of scents on the PER threshold, we categorized the effects of the 50 tested floral scents on feeding preference into 16 of all possible 27 theoretical types. We then conducted the same experiments with flies whose antennae or maxillary palps were ablated prior to PER test in a fly group naïve to floral scents and prior to the olfactory experience during sugar feeding in the other fly group in order to test how these organs were involved in the effect of the floral scent. The results suggested that olfactory inputs through these organs play different roles in forming or modifying feeding preferences. Thus, our study contributes to an understanding of underlying mechanisms associated with the convergent processing of olfactory inputs with taste information, which affects feeding preference or appetite.
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Affiliation(s)
- Toru Maeda
- Department of Biology, Graduate School of Science, Kobe University Kobe, Japan
| | - Miwako Tamotsu
- Department of Biology, Graduate School of Science, Kobe University Kobe, Japan
| | - Ryohei Yamaoka
- Department of Applied Biology, School of Science and Technology, Kyoto Institute of Technology Kyoto, Japan
| | - Mamiko Ozaki
- Department of Biology, Graduate School of Science, Kobe University Kobe, Japan
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20
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Siju KP, Bräcker LB, Grunwald Kadow IC. Neural mechanisms of context-dependent processing of CO2 avoidance behavior in fruit flies. Fly (Austin) 2015; 8:68-74. [PMID: 25483251 DOI: 10.4161/fly.28000] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The fruit fly, Drosophila melanogaster, innately avoids even low levels of CO2. CO2 is part of the so-called Drosophila stress odor produced by stressed flies, but also a byproduct of fermenting fruit, a main food source, making the strong avoidance behavior somewhat surprising. Therefore, we addressed whether feeding states might influence the fly's behavior and processing of CO2. In a recent report, we showed that this innate behavior is differentially processed and modified according to the feeding state of the fly. Interestingly, we found that hungry flies require the function of the mushroom body, a higher brain center required for olfactory learning and memory, but thought to be dispensable for innate olfactory behaviors. In addition, we anatomically and functionally characterized a novel bilateral projection neuron connecting the CO2 sensory input to the mushroom body. This neuron was essential for processing of CO2 in the starved fly but not in the fed fly. In this Extra View article, we provide evidence for the potential involvement of the neuromodulator dopamine in state-dependent CO2 avoidance behavior. Taken together, our work demonstrates that CO2 avoidance behavior is mediated by alternative neural pathways in a context-dependent manner. Furthermore, it shows that the mushroom body is not only involved in processing of learned olfactory behavior, as previously suggested, but also in context-dependent innate olfaction.
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Affiliation(s)
- K P Siju
- a Sensory Neurogenetics Group; Max-Planck Institute of Neurobiology; Martinsried, Germany
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21
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van Vugt JJFA, Hoedjes KM, van de Geest HC, Schijlen EWGM, Vet LEM, Smid HM. Differentially expressed genes linked to natural variation in long-term memory formation in Cotesia parasitic wasps. Front Behav Neurosci 2015; 9:255. [PMID: 26557061 PMCID: PMC4617343 DOI: 10.3389/fnbeh.2015.00255] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 09/07/2015] [Indexed: 12/14/2022] Open
Abstract
Even though learning and memory are universal traits in the Animal Kingdom, closely related species reveal substantial variation in learning rate and memory dynamics. To determine the genetic background of this natural variation, we studied two congeneric parasitic wasp species, Cotesia glomerata and C. rubecula, which lay their eggs in caterpillars of the large and small cabbage white butterfly. A successful egg laying event serves as an unconditioned stimulus (US) in a classical conditioning paradigm, where plant odors become associated with the encounter of a suitable host caterpillar. Depending on the host species, the number of conditioning trials and the parasitic wasp species, three different types of transcription-dependent long-term memory (LTM) and one type of transcription-independent, anesthesia-resistant memory (ARM) can be distinguished. To identify transcripts underlying these differences in memory formation, we isolated mRNA from parasitic wasp heads at three different time points between induction and consolidation of each of the four memory types, and for each sample three biological replicates, where after strand-specific paired-end 100 bp deep sequencing. Transcriptomes were assembled de novo and differential expression was determined for each memory type and time point after conditioning, compared to unconditioned wasps. Most differentially expressed (DE) genes and antisense transcripts were only DE in one of the LTM types. Among the DE genes that were DE in two or more LTM types, were many protein kinases and phosphatases, small GTPases, receptors and ion channels. Some genes were DE in opposing directions between any of the LTM memory types and ARM, suggesting that ARM in Cotesia requires the transcription of genes inhibiting LTM or vice versa. We discuss our findings in the context of neuronal functioning, including RNA splicing and transport, epigenetic regulation, neurotransmitter/peptide synthesis and antisense transcription. In conclusion, these brain transcriptomes provide candidate genes that may be involved in the observed natural variation in LTM in closely related Cotesia parasitic wasp species.
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Affiliation(s)
- Joke J F A van Vugt
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW) Wageningen, Netherlands
| | - Katja M Hoedjes
- Laboratory of Entomology, Wageningen University Wageningen, Netherlands
| | | | - Elio W G M Schijlen
- Applied Bioinformatics, Plant Research International Wageningen, Netherlands
| | - Louise E M Vet
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW) Wageningen, Netherlands ; Laboratory of Entomology, Wageningen University Wageningen, Netherlands
| | - Hans M Smid
- Laboratory of Entomology, Wageningen University Wageningen, Netherlands
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22
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Rohwedder A, Selcho M, Chassot B, Thum AS. Neuropeptide F neurons modulate sugar reward during associative olfactory learning ofDrosophilalarvae. J Comp Neurol 2015; 523:2637-64. [DOI: 10.1002/cne.23873] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 07/19/2015] [Accepted: 07/28/2015] [Indexed: 01/29/2023]
Affiliation(s)
- Astrid Rohwedder
- Department of Biology; University of Fribourg; Fribourg Switzerland
| | - Mareike Selcho
- Department of Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter; University of Würzburg; Würzburg Germany
| | - Bérénice Chassot
- Department of Biology; University of Fribourg; Fribourg Switzerland
| | - Andreas S. Thum
- Department of Biology; University of Fribourg; Fribourg Switzerland
- Department of Biology; University of Konstanz; Konstanz Germany
- Zukunftskolleg; University of Konstanz; Konstanz Germany
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23
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Lushchak OV, Carlsson MA, Nässel DR. Food odors trigger an endocrine response that affects food ingestion and metabolism. Cell Mol Life Sci 2015; 72:3143-55. [PMID: 25782410 PMCID: PMC11113394 DOI: 10.1007/s00018-015-1884-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 01/29/2015] [Accepted: 03/12/2015] [Indexed: 10/23/2022]
Abstract
Food odors stimulate appetite and innate food-seeking behavior in hungry animals. The smell of food also induces salivation and release of gastric acid and insulin. Conversely, sustained odor exposure may induce satiation. We demonstrate novel effects of food odors on food ingestion, metabolism and endocrine signaling in Drosophila melanogaster. Acute exposure to attractive vinegar odor triggers a rapid and transient increase in circulating glucose, and a rapid upregulation of genes encoding the glucagon-like hormone adipokinetic hormone (AKH), four insulin-like peptides (DILPs) and some target genes in peripheral tissues. Sustained exposure to food odors, however, decreases food intake. Hunger-induced strengthening of synaptic signaling from olfactory sensory neurons (OSNs) to brain neurons increases food-seeking behavior, and conversely fed flies display reduced food odor sensitivity and feeding. We show that increasing the strength of OSN signaling chronically by genetic manipulation of local peptide neuromodulation reduces feeding, elevates carbohydrates and diminishes lipids. Furthermore, constitutively strengthened odor sensitivity altered gene transcripts for AKH, DILPs and some of their targets. Thus, we show that food odor can induce a transient anticipatory endocrine response, and that boosted sensitivity to this odor affects food intake, as well as metabolism and hormonal signaling.
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Affiliation(s)
- Oleh V. Lushchak
- Department of Zoology, Stockholm University, 10691 Stockholm, Sweden
- Present Address: Department of Biochemistry and Biotechnology, Vasyl Stefanyk Precarpathian National University, Ivano-Frankivsk, Ukraine
| | | | - Dick R. Nässel
- Department of Zoology, Stockholm University, 10691 Stockholm, Sweden
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24
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Abstract
In flies and humans, bitter chemicals are known to inhibit sugar detection, but the adaptive role of this inhibition is often overlooked. At best, this inhibition is described as contributing to the rejection of potentially toxic food, but no studies have addressed the relative importance of the direct pathway that involves activating bitter-sensitive cells versus the indirect pathway represented by the inhibition of sugar detection. Using toxins to selectively ablate or inactivate populations of bitter-sensitive cells, we assessed the behavioral responses of flies to sucrose mixed with strychnine (which activates bitter-sensitive cells and inhibits sugar detection) or with L-canavanine (which only activates bitter-sensitive cells). As expected, flies with ablated bitter-sensitive cells failed to detect L-canavanine mixed with sucrose in three different feeding assays (proboscis extension responses, capillary feeding, and two-choice assays). However, such flies were still able to avoid strychnine mixed with sucrose. By means of electrophysiological recordings, we established that bitter molecules differ in their potency to inhibit sucrose detection and that sugar-sensing inhibition affects taste cells on the proboscis and the legs. The optogenetic response of sugar-sensitive cells was not reduced by strychnine, thus suggesting that this inhibition is linked directly to sugar transduction. We postulate that sugar-sensing inhibition represents a mechanism in insects to prevent ingesting harmful substances occurring within mixtures.
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25
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Abstract
Starved animals often exhibit elevated locomotion, which has been speculated to partly resemble foraging behavior and facilitate food acquisition and energy intake. Despite its importance, the neural mechanism underlying this behavior remains unknown in any species. In this study we confirmed and extended previous findings that starvation induced locomotor activity in adult fruit flies Drosophila melanogaster. We also showed that starvation-induced hyperactivity was directed toward the localization and acquisition of food sources, because it could be suppressed upon the detection of food cues via both central nutrient-sensing and peripheral sweet-sensing mechanisms, via induction of food ingestion. We further found that octopamine, the insect counterpart of vertebrate norepinephrine, as well as the neurons expressing octopamine, were both necessary and sufficient for starvation-induced hyperactivity. Octopamine was not required for starvation-induced changes in feeding behaviors, suggesting independent regulations of energy intake behaviors upon starvation. Taken together, our results establish a quantitative behavioral paradigm to investigate the regulation of energy homeostasis by the CNS and identify a conserved neural substrate that links organismal metabolic state to a specific behavioral output.
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26
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Feeding regulation in Drosophila. Curr Opin Neurobiol 2014; 29:57-63. [PMID: 24937262 DOI: 10.1016/j.conb.2014.05.008] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 05/17/2014] [Accepted: 05/22/2014] [Indexed: 11/22/2022]
Abstract
Neuromodulators play a key role in adjusting animal behavior based on environmental cues and internal needs. Here, we review the regulation of Drosophila feeding behavior to illustrate how neuromodulators achieve behavioral plasticity. Recent studies have made rapid progress in determining molecular and cellular mechanisms that translate the metabolic needs of the fly into changes in neuroendocrine and neuromodulatory states. These neuromodulators in turn promote or inhibit discrete feeding behavioral subprograms. This review highlights the links between physiological needs, neuromodulatory states, and feeding decisions.
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27
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König C, Schleyer M, Leibiger J, El-Keredy A, Gerber B. Bitter-sweet processing in larval Drosophila. Chem Senses 2014; 39:489-505. [PMID: 24833133 DOI: 10.1093/chemse/bju016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
"Sweet-" and "bitter-" tasting substances distinctively support attractive and aversive choice behavior, respectively, and therefore are thought to be processed by distinct pathways. Interestingly, electrophysiological recordings in adult Drosophila suggest that bitter and salty tastants, in addition to activating bitter, salt, or bitter/salt sensory neurons, can also inhibit sweet-sensory neurons. However, the behavioral significance of such a potential for combinatorial coding is little understood. Using larval Drosophila as a study case, we find that the preference towards fructose is inhibited when assayed in the background of the bitter tastant quinine. When testing the influence of quinine on the preference to other, equally preferred sweet tastants, we find that these sweet tastants differ in their susceptibility to be inhibited by quinine. Such stimulus specificity argues that the inhibitory effect of quinine is not due to general effects on locomotion or nausea. In turn, not all bitter tastants have the same potency to inhibit sweet preference; notably, their inhibitory potency is not determined by the strength of the avoidance of them. Likewise, equally avoided concentrations of sodium chloride differ in their potency to inhibit sugar preference. Furthermore, Gr33a-Gal4-positive neurons, while being necessary for bitter avoidance, are dispensable for inhibition of the sweet pathway. Thus, interactions across taste modalities are behaviorally significant and, as we discuss, arguably diverse in mechanism. These results suggest that the coding of tastants and the organization of gustatory behavior may be more combinatorial than is generally acknowledged.
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Affiliation(s)
- Christian König
- Department of Genetics, Institute of Biology, University of Leipzig, Talstr. 33, 04103 Leipzig, Germany, Research Group Molecular Systems Biology of Learning, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany
| | - Michael Schleyer
- Department of Genetics, Institute of Biology, University of Leipzig, Talstr. 33, 04103 Leipzig, Germany, Department of Genetics of Learning and Memory, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany
| | - Judith Leibiger
- Department of Genetics, Institute of Biology, University of Leipzig, Talstr. 33, 04103 Leipzig, Germany, Department of Genetics of Learning and Memory, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany
| | - Amira El-Keredy
- Department of Genetics, Faculty of Agriculture, Tanta University, Tanta-Kafr El-Sheikh Road, Seberbay Campus, 31527 Tanta, Egypt
| | - Bertram Gerber
- Department of Genetics of Learning and Memory, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany, Institute of Biology, Otto von Guericke University of Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany and Center for Behavioral Brain Sciences, Universitätsplatz 2, 39106 Magdeburg, Germany
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28
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Maeda T, Tamotsu S, Iwasaki M, Nisimura T, Shimohigashi M, Hojo MK, Ozaki M. Neuronal projections and putative interaction of multimodal inputs in the subesophageal ganglion in the blowfly, Phormia regina. Chem Senses 2014; 39:391-401. [PMID: 24718417 DOI: 10.1093/chemse/bju007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In flies, the maxillary palp possesses olfactory sensilla housing olfactory receptor neurons (ORNs), which project to the primary olfactory center, the antennal lobes (ALs). The labellum possesses gustatory sensilla housing gustatory receptor neurons (GRNs), which project to the primary gustatory center, the subesophageal ganglion (SOG). Using an anterograde staining method, we investigated the axonal projections of sensory receptor neurons from the maxillary palp and labellum to the SOG or other parts of brain in the blowfly, Phormia regina. We show that maxillary mechanoreceptor neurons and some maxillary ORNs project to the SOG where they establish synapses, whereas other maxillary ORNs terminate in the ipsi- and contralateral ALs. The labellar GRNs project to the SOG, and some of these neural projections partially overlap with ORN terminals from the maxillary palp. Based on these anterograde staining data and 3D models of the observed axonal projections, we suggest that interactions occur between GRNs from the labellum and ORNs from the maxillary palp. These observations strongly suggest that olfactory information from the maxillary palp directly interacts with the processing of gustatory information within the SOG of flies.
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Affiliation(s)
- Toru Maeda
- Department of Biology, Graduate School of Science, Kobe University, Kobe 657-8501, Japan,
| | - Satoshi Tamotsu
- Department of Biological Sciences, Faculty of Sciences, Nara Women's University, Nara 630-8506, Japan
| | - Masayuki Iwasaki
- Department of Earth System of Science, Division of Biology, Faculty of Science, Fukuoka University, Fukuoka 814-0180, Japan and
| | - Tomoyosi Nisimura
- Department of Materials and Life Science, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585, Japan
| | - Miki Shimohigashi
- Department of Earth System of Science, Division of Biology, Faculty of Science, Fukuoka University, Fukuoka 814-0180, Japan and
| | - Masaru K Hojo
- Department of Biology, Graduate School of Science, Kobe University, Kobe 657-8501, Japan
| | - Mamiko Ozaki
- Department of Biology, Graduate School of Science, Kobe University, Kobe 657-8501, Japan
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29
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Apostolopoulou AA, Mazija L, Wüst A, Thum AS. The neuronal and molecular basis of quinine-dependent bitter taste signaling in Drosophila larvae. Front Behav Neurosci 2014; 8:6. [PMID: 24478653 PMCID: PMC3902218 DOI: 10.3389/fnbeh.2014.00006] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Accepted: 01/06/2014] [Indexed: 12/12/2022] Open
Abstract
The sensation of bitter substances can alert an animal that a specific type of food is harmful and should not be consumed. However, not all bitter compounds are equally toxic and some may even be beneficial in certain contexts. Thus, taste systems in general may have a broader range of functions than just in alerting the animal. In this study we investigate bitter sensing and processing in Drosophila larvae using quinine, a substance perceived by humans as bitter. We show that behavioral choice, feeding, survival, and associative olfactory learning are all directly affected by quinine. On the cellular level, we show that 12 gustatory sensory receptor neurons that express both GR66a and GR33a are required for quinine-dependent choice and feeding behavior. Interestingly, these neurons are not necessary for quinine-dependent survival or associative learning. On the molecular receptor gene level, the GR33a receptor, but not GR66a, is required for quinine-dependent choice behavior. A screen for gustatory sensory receptor neurons that trigger quinine-dependent choice behavior revealed that a single GR97a receptor gene expressing neuron located in the peripheral terminal sense organ is partially necessary and sufficient. For the first time, we show that the elementary chemosensory system of the Drosophila larva can serve as a simple model to understand the neuronal basis of taste information processing on the single cell level with respect to different behavioral outputs.
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Affiliation(s)
| | - Lorena Mazija
- Department of Biology, University of Konstanz Konstanz, Germany
| | - Alexander Wüst
- Department of Biology, University of Konstanz Konstanz, Germany
| | - Andreas S Thum
- Department of Biology, University of Konstanz Konstanz, Germany
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Schnaitmann C, Garbers C, Wachtler T, Tanimoto H. Color discrimination with broadband photoreceptors. Curr Biol 2013; 23:2375-82. [PMID: 24268411 DOI: 10.1016/j.cub.2013.10.037] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 10/14/2013] [Accepted: 10/15/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Color vision is commonly assumed to rely on photoreceptors tuned to narrow spectral ranges. In the ommatidium of Drosophila, the four types of so-called inner photoreceptors express different narrow-band opsins. In contrast, the outer photoreceptors have a broadband spectral sensitivity and were thought to exclusively mediate achromatic vision. RESULTS Using computational models and behavioral experiments, we demonstrate that the broadband outer photoreceptors contribute to color vision in Drosophila. The model of opponent processing that includes the opsin of the outer photoreceptors scored the best fit to wavelength discrimination data. To experimentally uncover the contribution of individual photoreceptor types, we restored phototransduction of targeted photoreceptor combinations in a blind mutant. Dichromatic flies with only broadband photoreceptors and one additional receptor type can discriminate different colors, indicating the existence of a specific output comparison of the outer and inner photoreceptors. Furthermore, blocking interneurons postsynaptic to the outer photoreceptors specifically impaired color but not intensity discrimination. CONCLUSIONS Our findings show that receptors with a complex and broad spectral sensitivity can contribute to color vision and reveal that chromatic and achromatic circuits in the fly share common photoreceptors.
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Bräcker LB, Siju KP, Varela N, Aso Y, Zhang M, Hein I, Vasconcelos ML, Grunwald Kadow IC. Essential role of the mushroom body in context-dependent CO₂ avoidance in Drosophila. Curr Biol 2013; 23:1228-34. [PMID: 23770186 DOI: 10.1016/j.cub.2013.05.029] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 04/30/2013] [Accepted: 05/15/2013] [Indexed: 11/30/2022]
Abstract
Internal state as well as environmental conditions influence choice behavior. The neural circuits underpinning state-dependent behavior remain largely unknown. Carbon dioxide (CO2) is an important olfactory cue for many insects, including mosquitoes, flies, moths, and honeybees [1]. Concentrations of CO2 higher than 0.02% above atmospheric level trigger a strong innate avoidance in the fly Drosophila melanogaster [2, 3]. Here, we show that the mushroom body (MB), a brain center essential for olfactory associative memories [4-6] but thought to be dispensable for innate odor processing [7], is essential for CO2 avoidance behavior only in the context of starvation or in the context of a food-related odor. Consistent with this, CO2 stimulation elicits Ca(2+) influx into the MB intrinsic cells (Kenyon cells: KCs) in vivo. We identify an atypical projection neuron (bilateral ventral projection neuron, biVPN) that connects CO2 sensory input bilaterally to the MB calyx. Blocking synaptic output of the biVPN completely abolishes CO2 avoidance in food-deprived flies, but not in fed flies. These findings show that two alternative neural pathways control innate choice behavior, and they are dependent on the animal's internal state. In addition, they suggest that, during innate choice behavior, the MB serves as an integration site for internal state and olfactory input.
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Affiliation(s)
- Lasse B Bräcker
- Sensory Neurogenetics Research Group, Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany
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