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Published on: July 27, 2017
Aversive odorant causing appetite decrease downregulates tyrosine decarboxylase gene expression in the olfactory
1Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501, Japan. yishida@eagle.kobe-u.ac.jp
Die Naturwissenschaften
|November 22, 2011
Summary
d-Limonene exposure reduces tyramine (TA) levels in blowflies by decreasing tyrosine decarboxylase (Tdc) expression in antennae. This impacts olfactory signaling and feeding behavior.
Area of Science:
- Neuroscience
- Insect Physiology
- Molecular Biology
Background:
- d-Limonene exposure in blowflies (Phormia regina) inhibits feeding behavior by reducing tyramine (TA) levels.
- Tyramine is synthesized by tyrosine decarboxylase (Tdc) and converted to octopamine (OA) by TA ß-hydroxylase (Tbh).
- Understanding TA regulation is crucial for explaining behavioral changes induced by environmental factors.
Purpose of the Study:
- To investigate the molecular mechanisms by which d-limonene alters tyramine (TA) levels in the blowfly Phormia regina.
- To clone and characterize the genes encoding tyrosine decarboxylase (Tdc) and TA ß-hydroxylase (Tbh) in P. regina.
- To determine the role of PregTdc expression in the antennae in mediating the effects of d-limonene on TA levels and behavior.
Main Methods:
- Cloning of tyrosine decarboxylase (Tdc) and TA ß-hydroxylase (Tbh) cDNAs from Phormia regina (PregTdc and PregTbh).
- Analysis of PregTdc and PregTbh gene expression patterns in different tissues.
- Quantitative assessment of PregTdc expression in response to d-limonene exposure.
- Immunohistochemical localization of PregTdc and OA/TA receptors.
Main Results:
- Cloned PregTdc and PregTbh showed high sequence identity to Drosophila melanogaster orthologs.
- PregTdc was primarily expressed in sensory organs (antenna, labellum, tarsus), while PregTbh was mainly in the head.
- d-Limonene exposure significantly reduced PregTdc expression specifically in the antenna, correlating with decreased TA levels.
- PregTdc was localized to thin-walled sensilla, and OA/TA receptors to thick-walled sensilla.
Conclusions:
- d-Limonene inhibits blowfly feeding behavior by downregulating PregTdc expression in antennal olfactory receptor neurons.
- Reduced PregTdc leads to decreased tyramine (TA) synthesis in the antennae.
- TA likely plays a role in conveying aversive odorant information to the central nervous system via antennal pathways.
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