Tarsal Chemosensilla Research Articles

Contact Chemosensory Genes Identified in Leg Transcriptome of Apis cerana cerana (Hymenoptera: Apidae).

Correct gustatory recognition and selection of foods both within and outside the hive by honey bee workers are fundamental to the maintenance of colonies. The tarsal chemosensilla located on the legs of workers are sensitive to nonvolatile compounds and proposed to be involved in gustatory detection. However, little is known about the molecular mechanisms underlying the gustatory recognition of foods in honey bees. In the present study, RNA-seq was performed with RNA samples extracted from the legs of 1-, 10-, and 20-d-old workers of Apis cerana cerana Fabricius, a dominant indigenous crop pollinator with a keen perception ability for phytochemicals. A total of 124 candidate chemosensory proteins (CSPs), including 15 odorant-binding proteins (OBPs), 5 CSPs, 7 gustatory receptors (GRs), 2 sensory neuron membrane proteins (SNMPs), and 95 odorant receptors (ORs), were identified from the assembled leg transcriptome. In silico analysis of expression showed that 36 of them were differentially expressed among the three different ages of A. c. cerana workers. Overall, the genes encoding OBPs and CSPs had great but extremely variable FPKM values and thus were highly expressed in the legs of workers, whereas the genes encoding ORs, GRs, and SNMPs (except SNMP2) were expressed at low levels. Tissue-specific expression patterns indicated that two upregulated genes, AcerOBP15 and AcerCSP3, were predominately expressed in the legs of 20-d-old foragers, suggesting they may play an essential role in gustatory recognition and selection of plant nectars and pollens. This study lays a foundation for further research on the feeding preferences of honey bees.

Morphological and electrophysiological differences in tarsal chemosensilla between the wild silkmoth Bombyx mandarina and the domesticated species Bombyx mori

Gustatory and olfactory senses of phytophagous insects play important roles in the recognition of host plants. In the domestic silkmoth Bombyx mori and its wild species Bombyx mandarina, the morphologies and responses of adult olfactory organs (antennae) have been intensely investigated. However, little is known about these features of adult gustatory organs and the influence of domestication on the gustatory sense. Here we revealed that both species have two types of sensilla (thick [T] and slim [S] types) on the fifth tarsomeres of the adult legs. In both species, females have 3.6–6.9 times more T-sensilla than males. Therefore, T-sensilla seem to play more important roles in females than in males. Moreover, gustatory cells of T-sensilla of B. mandarina females responded intensely to mulberry leaf extract in electrophysiological experiments, while T-sensilla of B. mori females (N4 strain) hardly responded to mulberry leaf extract. These results suggest that T-sensilla of B. mandarina females are involved in the recognition of oviposition sites. We also observed that, in three B. mori strains (N4, p50T, and Kinshu × Showa), the densities of sensilla on the fifth tarsomeres were much lower than in B. mandarina. These results indicate that domestication has influenced the tarsal gustatory system of B. mori.

Taste input from tarsal sensilla is related to egg‐laying behavior in Papilio hospiton

AbstractIn herbivorous insects, host selection involves various sensory modalities (sight, smell, taste), but the contact chemoreceptors capable of detecting stimuli both from host and non‐host plants play an important role in the final steps of oviposition behavior. Female butterflies scratch and drum the leaf surface and taste the compounds present in plant saps with their tarsal chemosensilla. We assumed that tarsal taste sensitivity may be related to the breadth of host selection in ovipositing females of Papilio hospitonGéné (Lepidoptera: Papilionidae). The spike activity of tarsal taste basiconic sensilla was recorded in response to stimulation with NaCl, bitter compounds, and carbohydrates, with the aim of characterizing the gustatory receptor neurons (GRNs) and of comparing the response patterns in the light of differences in acceptability of host plants. Then we studied the sensitivity of GRNs to saps of the host plants Ferula communis L., Peucedanum paniculatumLoisel, Pastinaca latifolia (Duby) DC. (all Apiaceae), and Ruta lamarmorae Bacch., Brullo et Giusso (Rutaceae), and evaluated the relationship between taste sensitivity and oviposition preference. The results indicate that (1) each sensillum houses sugar‐, bitter‐, and salt‐sensitive cells; (2) the spike activity of the gustatory neurons in response to plant saps produces a different response pattern across all active GRNs; and (3) the number of eggs laid on each plant is highest on F. communis and lowest on R. lamarmorae. These results suggest that the varying activity of the tarsal GRNs may affect host plant acceptability and that ovipositing females of P. hospiton seem to be able to discriminate between host plants.

Mode of Action of the Natural Insecticide, Decaleside Involves Sodium Pump Inhibition.

Decalesides are a new class of natural insecticides which are toxic to insects by contact via the tarsal gustatory chemosensilla. The symptoms of their toxicity to insects and the rapid knockdown effect suggest neurotoxic action, but the precise mode of action and the molecular targets for decaleside action are not known. We have presented experimental evidence for the involvement of sodium pump inhibition in the insecticidal action of decaleside in the cockroach and housefly. The knockdown effect of decaleside is concomitant with the in vivo inhibition of Na+, K+ -ATPase in the head and thorax. The lack of insecticidal action by experimental ablation of tarsi or blocking the tarsal sites with paraffin correlated with lack of inhibition of Na+- K+ ATPase in vivo. Maltotriose, a trisaccharide, partially rescued the toxic action of decaleside as well as inhibition of the enzyme, suggesting the possible involvement of gustatory sugar receptors. In vitro studies with crude insect enzyme preparation and purified porcine Na+, K+ -ATPase showed that decaleside competitively inhibited the enzyme involving the ATP binding site. Our study shows that the insecticidal action of decaleside via the tarsal gustatory sites is causally linked to the inhibition of sodium pump which represents a unique mode of action. The precise target(s) for decaleside in the tarsal chemosensilla and the pathway linked to inhibition of sodium pump and the insecticidal action remain to be understood.

Neuropathological effect of dimethyl disulfide on neurons of the desert locust Schistocerca gregaria

Botanical insecticides have introduced a new concept in insecticide research. In response to insect attacks, some plants can release volatile compounds that alter insect metabolism and nervous system activity. In the present study, changes in the electrical activity of chemoreceptors and alteration of the fine structure of metathoracic ganglia of desert locust were examined after acute exposure to dimethyl disulfide (DMDS), a sulfur compound released from Allium porrum. Animals were exposed to 1/4 LC50 of DMDS (0.375μl/L air) and electrophysiological and electron-microscopical studies were carried out. Application of DMDS showed an increase in the activity of deterrent cells present in tarsal chemosensilla of locust. On the other hand, evident degenerative changes in the neurons, neuroglia, neuropile and synaptic vesicles were observed in the metathoracic ganglia of DMDS-treated animals. These findings revealed that pest control using DMDS might be feasible and future work is highly recommended in this respect.

Drosophila Evaluates and Learns the Nutritional Value of Sugars

Living organisms need to search for and ingest nutritional chemicals, and gustation plays a major role in detecting and discriminating between chemicals present in the environment. Using Drosophila as a model organism, we asked whether animals have the ability to evaluate the nutritional value of sugars. In flies, chemosensilla on the tarsi and labellum are the gustatory organs used to discriminate between edible and nonedible compounds [1, 2]. We noticed that Drosophila do not assign nutritional values to all sweet chemicals. D-arabinose is sweet to flies, but it provides them with no nutrition. By contrast, the sugar alcohol D-sorbitol is not sensed as sweet, but flies can live on it. We performed behavioral and electrophysiological measurements to confirm these gustatory and feeding responses. We found that Drosophila can learn the nutritional value of nonsweet D-sorbitol when it is associated with an odor cue. The learning process involved the synapsin molecule, suggesting that a neuronal mechanism is involved. We propose that Drosophila uses neural machinery to detect, evaluate, and learn the nutritional value of foods after ingestion.

Contribution of the inositol 1,4,5-trisphosphate transduction cascade to the detection of “bitter” compounds in blowflies

Bitter taste detection is very important for many species including flies, because it prevents the ingestion of toxic food. Although it has been known that flies have specific bitter-sensitive taste cells in their contact chemosensilla, the mechanism by which those cells transduce the chemical signal into electrical activity has remained elusive. In this study, we first confirmed that type D4 and D5 tarsal chemosensilla of the blowfly Phormia regina responded well to bitter substances. Then, recording impulses from type D4 chemosensilla, we examined the possibility that a G-protein-coupled inositol 1,4,5-trisphosphate (IP 3)-dependent transduction cascade is of importance in the bitter-sensitive taste cells. We found that the response to bitter substances was depressed by specific inhibitors of G-protein, phospholipase C, or IP 3 receptor in the tarsal taste receptor cells. These results suggest that G-proteins mediate the IP 3 pathway in the transduction cascade in bitter-sensitive receptor cells.

Electrophysiological responses of Chemoreceptor neurons in Calliphora vicina (Diptera: Calliphoridae) to morphine sulfate and its implications in forensic entomology

Event Abstract Back to Event Electrophysiological responses of Chemoreceptor neurons in Calliphora vicina (Diptera: Calliphoridae) to morphine sulfate and its implications in forensic entomology Nagwa Refai1*, Omar A. Shalaby1, Tarek I. Tantawi1, Ibrahim Gaaboub2 and Hedayat A Ghaffar1 1 Alexandria University, Zoology, Department, Faculty of Science, Egypt 2 Banha University, Plant protection, Department, Faculty of Agriculture, Egypt The major task of a forensic entomologist is to determine an accurate post-mortem interval (PMI) by analyzing the development or succession of necrophagous insects and other arthropods on the carcass. Blow flies (Diptera: Calliphoridae) are the first arrival at a death scene and are attracted to carcasses through volatile compounds emitted during different stages of decomposition. It is therefore probable that flies can easily distinguish between chemical signatures of early and late decay stages. Blowflies respond to sugars, salts and water through the activation of specific chemoreceptor within the antennal, labellar and tarsal chemosensilla. These insects also detect deterrent stimuli through a specific "deterrent" chemoreceptor within their sensilla called the "fifth" cell. Several investigations of chemosensory sensilla in various insect groups have been performed to date, but relatively little information involving forensically important fly species. Due to this deficiency, the purpose of this study was to investigate the electrophysiological responses of receptor neurons on the antennae, labium and tarsus of a forensically important blowfly (Calliphora vicina) to different doses of morphine in decomposing tissues as well as odors emitted from the underneath soil. Electrophysiological recordings indicate that the best responding cell to morphine sulfate is the 5th cell "deterrent cell" in all stimulating sites but with different degrees of sensitivity. These results strongly suggest that morphine sulfate with its different doses has a significant repellent effect on the attractiveness of Calliphora vicina. These conclusions should be considered when estimating PMI otherwise under estimation will result. Keywords: Calliphora vicina, Chemoreceptor neurons, PMI Conference: 3rd Mediterranean Conference of Neuroscience , Alexandria, Egypt, 13 Dec - 16 Dec, 2009. Presentation Type: Poster Presentation Topic: Cognition Citation: Refai N, Shalaby OA, Tantawi TI, Gaaboub I and Ghaffar H (2009). Electrophysiological responses of Chemoreceptor neurons in Calliphora vicina (Diptera: Calliphoridae) to morphine sulfate and its implications in forensic entomology. Front. Neurosci. Conference Abstract: 3rd Mediterranean Conference of Neuroscience . doi: 10.3389/conf.neuro.01.2009.16.135 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 24 Nov 2009; Published Online: 24 Nov 2009. * Correspondence: Nagwa Refai, Alexandria University, Zoology, Department, Faculty of Science, Alexandria, Egypt, nagwa2012@hotmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Nagwa Refai Omar A Shalaby Tarek I Tantawi Ibrahim Gaaboub Hedayat A Ghaffar Google Nagwa Refai Omar A Shalaby Tarek I Tantawi Ibrahim Gaaboub Hedayat A Ghaffar Google Scholar Nagwa Refai Omar A Shalaby Tarek I Tantawi Ibrahim Gaaboub Hedayat A Ghaffar PubMed Nagwa Refai Omar A Shalaby Tarek I Tantawi Ibrahim Gaaboub Hedayat A Ghaffar Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Clonidine effects on protein and carbohydrate electrophysiological responses of labellar and tarsal sensilla in Phormia regina

The electrophysiological response of labellar and tarsal chemosensilla in the blowfly Phormia regina was studied in response to a complex stimulus naturally encountered by flies such as sheep faeces, and to beef liver, a proteinaceous feeding source. Responses were investigated both before or after injection of clonidine, an octopamine agonist previously shown to enhance sucrose ingestion, while decreasing that of proteins. As assessed by single sensillum recordings, the four different chemosensory – “salt”, “sugar”, “deterrent” and “water” – cells were all activated by both stimuli, regardless of sex and sensillum type, the “sugar” one being in all cases the most sensitive to beef liver before clonidine injection. Clonidine treatment affected neither labellar nor tarsal sensitivity to sucrose. Conversely, clonidine-injected flies showed a significant increase in the activity of the “deterrent” cell to beef liver, thus accounting for a decrease in protein ingestion. This study for the first time provides evidence of a key role of a clonidine-sensitive peripheral taste sensitivity in down-regulation of protein ingestion in blowflies. Correlation between peripheral sensitivity and behavioural output is discussed.

Identification of cytochrome P450 and glutathione- S-transferase genes preferentially expressed in chemosensory organs of the swallowtail butterfly, Papilio xuthus L.

The swallowtail butterfly, Papilio xuthus L., feeds exclusively on members of the plant family, Rutaceae. Female butterflies lay eggs in response to specific chemicals contained in their host plants. They perceive a variety of polar compounds as oviposition stimulants through the tarsal chemosensilla of the foreleg by drumming upon the leaf surface. We undertook an expressed sequence tag (EST) analysis to identify the chemosensory-related genes that are expressed in chemosensilla on the tarsus of P. xuthus. Several genes that showed similarity with biotransformation enzymes were identified from the ESTs. Among them, a cytochrome P450 and a glutathione- S-transferase (GST) were preferentially expressed in the chemosensory organs. We have determined the structure of both cDNA and genomic sequences encoding these enzymes and designated the P450 as CYP341A2, a novel member of CYP341A subfamily, and the GST as GST-pxcs1, respectively. We observed a localized expression of CYP341A2 at the base of tarsal chemosensilla by in situ hybridization. These results suggest that these degrading enzymes play a role in the chemosensory reception for host plant recognition.

Identification of amine receptors from a swallowtail butterfly, Papilio xuthus L.: cloning and mRNA localization in foreleg chemosensory organ for recognition of host plants

The swallowtail butterfly, Papilio xuthus L., feeds exclusively on members of the plant family, Rutaceae. Female butterflies lay eggs in response to specific chemicals contained in their host plants. They perceive a variety of polar compounds as oviposition stimulants through the tarsal chemosensilla of the foreleg by drumming upon the leaf surface. Some biogenic amine analogs have been characterized as oviposition stimulants. We have cloned three amine receptors, serotonin, tyramine, and dopamine, from cDNA derived from foreleg tarsus of P. xuthus, and determined structures of both cDNA and genomic genes. The phenylethylamine (tyramine and dopamine) receptors were expressed preferentially in brain and chemosensory organs. Moreover, we observed the localized expression of dopamine receptors at the base of tarsal chemosensilla by in situ hybridization. These results suggest that amine receptors in tarsal chemosensilla have a functional role in chemoreception for host plant recognition.

Effects ofSolanum glycoalkaloids on chemosensilla in the Colorado potato beetle

Steroidal glycoalkaloids, found in species of the Solanaceae, elicit bursting activity in galeal and tarsal chemosensilla of adult Colorado potato beetles. The effect has an average latency of 6-12 sec, depending on the sensillum/alkaloid combination. A 20-sec alkaloid treatment is often suffficient to render galeal sensilla unresponsive to gamma-aminobutyric acid, normally an effective stimulant. The alkaloids have similar effects on galeal sensilla of larval Colorado potato beetles and on labellar chemosensilla of the blowfly. It is concluded that these compounds act independently of any specialized chemoreceptor in the Colorado potato beetle, and that association of the Colorado potato beetle with solanaceous plants has not led to evolution of a specific receptor forSolanum glycoalkaloids.

Electrical resistance and spike activity in tarsal chemosensilla ofPhormia regina (Meig.)

The relationship between hair electrical resistance and responsiveness to stimulation has been investigated in the tarsal chemosensilla ofPhormia regina. Results showed that the lower the hair electrical resistance, the higher is the spike-firing frequency.