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Peláez JN, Bernstein S, Okoro J, Rodas E, Liang I, Leipertz A, Marion-Poll F, Whiteman NK. Taste evolution in an herbivorous drosophilid. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.27.582299. [PMID: 38464294 PMCID: PMC10925181 DOI: 10.1101/2024.02.27.582299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Plant secondary metabolites pose a challenge for generalist herbivorous insects because they are not only potentially toxic, they also may trigger aversion. On the contrary, some highly specialized herbivorous insects evolved to use these same compounds as 'token stimuli' for unambiguous determination of their host plants. Two questions that emerge from these observations are how recently derived herbivores evolve to overcome this aversion to plant secondary metabolites and the extent to which they evolve increased attraction to these same compounds. In this study, we addressed these questions by focusing on the evolution of bitter taste preferences in the herbivorous drosophilid Scaptomyza flava, which is phylogenetically nested deep in the paraphyletic Drosophila. We measured behavioral and neural responses of S. flava and a set of non-herbivorous species representing a phylogenetic gradient (S. pallida, S. hsui, and D. melanogaster) towards host- and non-host derived bitter plant compounds. We observed that S. flava evolved a shift in bitter detection, rather than a narrow shift towards glucosinolates, the precursors of mustard-specific defense compounds. In a dye-based consumption assay, S. flava exhibited shifts in aversion toward the non-mustard bitter, plant-produced alkaloids caffeine and lobeline, and reduced aversion towards glucosinolates, whereas the non-herbivorous species each showed strong aversion to all bitter compounds tested. We then examined whether these changes in bitter preferences of S. flava could be explained by changes in sensitivity in the peripheral nervous system and compared electrophysiological responses from the labellar sensilla of S. flava, S. pallida, and D. melanogaster. Using scanning electron microscopy, we also created a map of labellar sensilla in S. flava and S. pallida. We assigned each sensillum to a functional sensilla class based on their morphology and initial response profiles to bitter and sweet compounds. Despite a high degree of conservation in the morphology and spatial placement of sensilla between S. flava and S. pallida, electrophysiological studies revealed that S. flava had reduced sensitivity to glucosinolates to varying degrees. We found this reduction only in I type sensilla. Finally, we speculate on the potential role that evolutionary genetic changes in gustatory receptors between S. pallida and S. flava may play in driving these patterns. Specifically, we hypothesize that the evolution of bitter receptors expressed in I type sensilla may have driven the reduced sensitivity observed in S. flava, and ultimately, its reduced bitter aversion. The S. flava system showcases the importance of reduced aversion to bitter defense compounds in relatively young herbivorous lineages, and how this may be achieved at the molecular and physiological level.
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Affiliation(s)
- Julianne N. Peláez
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Susan Bernstein
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Judith Okoro
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Esteban Rodas
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Irene Liang
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Anna Leipertz
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Frédéric Marion-Poll
- Evolution, Genomes, Behaviour and Ecology, IDEEV, CNRS, Université Paris-Saclay, IRD, Gif-sur-Yvette, France
- Université Paris-Saclay, AgroParisTech, 91120 Palaiseau, France
| | - Noah K. Whiteman
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
- Department of Molecular & Cellular Biology, University of California-Berkeley, Berkeley, CA 94720, USA
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Li X, Sun Y, Gao S, Li Y, Liu L, Zhu Y. Taste coding of heavy metal ion-induced avoidance in Drosophila. iScience 2023; 26:106607. [PMID: 37128604 PMCID: PMC10148117 DOI: 10.1016/j.isci.2023.106607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 01/04/2023] [Accepted: 03/30/2023] [Indexed: 05/03/2023] Open
Abstract
Increasing pollution of heavy metals poses great risks to animals globally. Their survival likely relies on an ability to detect and avoid harmful heavy metal ions (HMIs). Currently, little is known about the neural mechanisms of HMI detection. Here, we show that Drosophila and related species of Drosophilidae actively avoid toxic HMIs at micromolar concentrations. The high sensitivity to HMIs is biologically relevant. Particularly, their sensitivity to cadmium is as high as that to the most bitter substance, denatonium. Detection of HMIs in food requires Gr66a + gustatory neurons but is independent of bitter-taste receptors. In these neurons, the ionotropic receptors IR76b, IR25a, and IR7a are required for the perception of heavy metals. Furthermore, IR47a mediates the activation of a distinct group of non-Gr66a + gustatory neurons elicited by HMIs. Together, our findings reveal a surprising taste quality represented by noxious metal ions.
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Affiliation(s)
- Xiaonan Li
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuanjie Sun
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shan Gao
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Li
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Li Liu
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Zhu
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
- Corresponding author
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El Kholy S, Al Naggar Y. Exposure to polystyrene microplastic beads causes sex-specific toxic effects in the model insect Drosophila melanogaster. Sci Rep 2023; 13:204. [PMID: 36604504 PMCID: PMC9814852 DOI: 10.1038/s41598-022-27284-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 12/29/2022] [Indexed: 01/06/2023] Open
Abstract
The toxicity of MPs on aquatic creatures has been extensively studied, but little attention was paid to terrestrial organisms. To fill this gab, we conducted a series of experiments using Drosophila as a model organism to understand whether exposure to different concentrations (0.005, 0.05, 0.5 µg/ml) of polystyrene microplastics (PS-MPs) beads (2 µm in size) can impact flies feeding activity, digestion and excretion. The ability of flies to distinguish between normal and PS-MPs treated food media was tested first, and then we evaluated the effects of a 7-day short-term exposure to PS-MPs on food intake, mortality, starvation resistance, fecal pellet count, and the cellular structure of mid gut cells. The results revealed that flies can really differentiate and ignore MPs-treated food. We discovered sex-specific effects, with male flies being more sensitive to PS-MPs, with all males dying after 14 days when exposed to 0.5 µg/ml of PS-MPs, whereas female flies survived more. All male flies exposed to PS-MPs died after 24 h of starvation. Midgut cells showed concentration-dependent necrosis and apoptosis in response to PS-MPs. Our findings provide new insights into MPs toxicity on terrestrial organisms and giving a warning that management measures against MPs emission must be taken.
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Affiliation(s)
- Samar El Kholy
- Zoology Department, Faculty of Science, Tanta University, Tanta, 31527, Egypt.
| | - Yahya Al Naggar
- Zoology Department, Faculty of Science, Tanta University, Tanta, 31527, Egypt.
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