Biology subjects

Wang, C.-Z.

Publications and source records attributed to Wang, C.-Z..

6 recordsLinked to original sources

bioRxiv2023

Sucrose taste receptors differ in larval and adult stages of a moth

Almost all herbivorous insects feed on plants and use sucrose as a feeding stimulant, but the molecular basis of their sucrose reception remains unclear. Helicoverpa armigera as a notorious crop pest worldwide mainly feeds on reproductive organs of many plant species in the larval stage, and its adult draws nectar. In this study, we determined that the sucrose sensory neurons located in the contact chemosensilla of larval maxillary galeae were 100-1000 times more sensitive to sucrose than those of adult antennae, tarsi and proboscis. Using the Xenopus expression system, we discovered that Gr10 highly expressed in the larval sensilla was specifically tuned to sucrose, while Gr6 highly expressed in the adult sensilla responded to fucose, sucrose and fructose. Moreover, using CRISPR/Cas9, we revealed that Gr10 was mainly used by larvae to detect lower sucrose, while Gr6 was primarily used by adults to detect higher sucrose and other saccharides, which results in differences in selectivity and sensitivity between larval and adult sugar sensory neurons. Our results demonstrate the sugar receptors in this moth are evolved to adapt towards the larval and adult foods with different types and amounts of sugar, and fill in a gap in sweet taste of animals.

ecology↗

bioRxiv2020

A sweet-tasting sugar drives aversive responses in caterpillars

Exploring botanical biopesticide is one of the eco-friendly approaches for pest control in current crop protection. L-arabinose, a plant-specific and less absorptive pentose, is known for its selective inhibitory effect on the sucrose digestion in mammals. In this study, we investigated the effects of L-arabinose on the feeding preference, the peripheral gustatory perception, the larval development, as well as the activity of intestinal sucrase of an insect pest species, the cotton bollworm Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae), in an attempt to explore the antifeedant activities of this pentose. The results showed that L-arabinose deterred the feeding preferences of H. armigera caterpillars for its two host plants and two phagostimulants, the tobacco, the pepper, the sucrose and the fructose. Gustatory receptor neurons (GRNs) sensitive to L-arabinose were not found in the peripheral maxillary sensilla of H. armigera caterpillars, but the sensitivities of GRNs sensitive to sucrose, fructose and tobacco saps were suppressed by the additions of L-arabinose. Exposure of H. armigera caterpillars to dietary L-arabinose resulted in a prolonged larval developmental duration, a suppressed activity of intestinal sucrase and a reduced glucose level in midgut. In vitro, L-arabinose inhibited activities of the intestinal sucrase of H. armigera caterpillars in an uncompetitive manner. Taken together, these findings demonstrate that L-arabinose is a behavioral, gustatory and physiological inhibitor to caterpillars of the extremely generalist pest species H. armigera, suggesting the great potential of L-arabinose to be an effective antifeedant.

animal behavior and cognition↗

bioRxiv2020

A gustatory receptor tuned to the steroid plant hormone brassinolide in Plutella xylostella (Lepidoptera: Plutellidae)

Feeding and oviposition deterrents help phytophagous insects to identify host plants. The taste organs of phytophagous insects contain bitter gustatory receptors (GRs). To explore their function, we focused on PxylGr34, a bitter GR in Plutella xylostella (L.). We detected abundant PxylGr34 transcripts in the larval head and specific expression of PxylGr34 in the antennae of females. Analyses using the Xenopus oocyte expression system and two-electrode voltage-clamp recording showed that PxylGr34 is specifically tuned to the plant hormone brassinolide (BL) and its analog 24-epibrassinolide. Electrophysiological analyses revealed that the medial sensilla styloconica on the maxillary galea of the 4th instar larvae are responsive to BL. Dual-choice bioassays demonstrated that BL inhibits larval feeding and female ovipositing. Knock-down of PxylGr34 by RNAi abolished BL-induced feeding inhibition. These results shed light on gustatory coding mechanisms and deterrence of insect feeding and ovipositing, and may be useful for designing plant hormone-based pest management strategies.

ecology↗

bioRxiv2020

Contribution of odorant binding proteins to olfactory detection of (Z)-11-hexadecenal in Helicoverpa armigera

Helicoverpa armigera utilizes (Z)-11-hexadecenal (Z11-16:Ald) as its major sex pheromone component. Three pheromone binding proteins (PBPs) and two general odorant binding proteins (GOBPs) are abundantly expressed in male antennae of H. armigera. However, their precise roles in the olfactory detection of Z11-16:Ald remain enigmatic. To answer this question, we first synthesized the antibody against HarmOR13, a pheromone receptor (PR) primarily responding to Z11-16:Ald and mapped the local associations between PBPs / GOBPs and HarmOR13. Immunostaining showed that HarmPBPs and HarmGOBPs were localized in the supporting cells of sensilla trichodea and sensilla basiconica respectively. In particular, HarmPBP1 and HarmPBP2 were colocalized in the cells surrounding the olfactory receptor neurons (ORNs) expressing HarmOR13. Next, using two noninterfering binary expression tools, we heterologously expressed HarmPBP1, HarmPBP2 and HarmOR13 in Drosophila T1 sensilla to validate the functional interplay between PBPs and HarmOR13. We found that the addition of HarmPBP1 or HarmPBP2 significantly increased the sensitivity of HarmOR13 to Z11-16:Ald. However, the presence of either HarmPBP1 or HarmPBP2 was ineffective to change the tuning breadth of HarmOR13. Taken together, our results support the idea that PBPs are contributors to the peripheral olfactory sensitivity but do not affect the selectivity. Lastly, we discovered that HarmOR13 and the Drosophila OR67d employed a similar coding mechanism to detect pheromones, suggesting that pheromone detection across different insect orders appears to co-opt a conserved molecular principle to recognize pheromone ligands.

neuroscience↗

bioRxiv2019

Early-generated interneurons regulate neuronal circuit formation during early postnatal development

A small subset of interneurons that are generated earliest as pioneer neurons are the first cohort of neurons that enter the neocortex. However, it remains largely unclear whether these early-generated interneurons (EGIns) predominantly regulate neocortical circuit formation. Using inducible genetic fate mapping to selectively labeled EGIns and pseudo-random interneurons (pRIns), we found that EGIns exhibited more mature electrophysiological and morphological properties and higher synaptic connectivity than pRIns at early postnatal stages. In addition, when stimulating one cell, the proportion of EGIns that influence spontaneous network synchronization is significantly higher than that of pRIns. Importantly, toxin-mediated ablation of EGIns after birth significantly reduce spontaneous network synchronization and decrease inhibitory synaptic transmission during the first postnatal week. These results suggest that EGIns can shape developing networks and may contribute to the refinement of neuronal connectivity before the establishment of the adult neuronal circuit.

neuroscience↗

bioRxiv2018

Dedicated acetic acid preference coded by broad spectrum ionotropic receptors in a moth species

Acetic acid as one of the food related odorant cues attracts many insect species. In the moth Mythimna separata, the olfaction of acid was coded via multiple pathways including 3 sensilla types on the antennae and 3 glomeruli in the antennal lobes. Among, suitable dosages of acetic acid exclusively activated DC3 glomerulus that receives integrated projections across sensilla types, which drives attractiveness and feeding attempts of the moth. This circuit encodes broad spectrum ionotropic receptors 8a, 75q1 and 75q2 which were sufficient to confer acid responsiveness in Xenopus oocytes. Ir75q2 was expressed in vivo with Ir75q1 and it enhanced sensitivity of the receptor functional group toward acids. Furthermore, Ir75q1 and Ir75q2 are both necessary for the moth to conduct acetic acid induced reactions of sensilla, DC3 glomerulus as well as attractiveness. Together, it reveals that an indispensable tetramer IR-based unit is employed to fulfill acetic acid specialized preference under suitable dosages through balancing of transcription and peripheral coding. Understanding of the Ir75q1/2 olfactory pathway provides insights into investigations on acid sensory process in insects.\n\nAuthor SummaryThe preference to acids are common in various organisms, and it may involve both olfactory and gustatory reception. In particular, airborne acidity volatiles can be sensed through antennae of insects and later assessed to help locating foraging, mating, and egg laying sites. However, these stimulatory processes can only be delivered by suitable dosages of acids, as we all know that, high acidity could be fatal in most circumstances. To date, avoidance to acids has been well explained in insects, but attractiveness and its basis remain uncharted. In the brain of oriental armyworm Mythimna separata, we have located 3 olfactory pathways which may play roles in acetic acid reception. Fortunately, when acetic acid was applied at attractive dosages, it only activated 1 dedicated pathway among the three. Later we found that this attractiveness pathway employed two ionotropic receptor genes namely Ir75q1 and Ir75q2, to successfully deliver this trait. Both genes were necessary for the moth to conduct acetic acid preference, but their roles are different. Ir75q1 recognized the acetic acid ligand and Ir75q2 later amplify the sensitivity. By comparing with evidences from electrophysiology and brain imaging tests, we found that the expression bias of either of the two genes has caused the separation of the pathways. It has been revealed in this moth that a smart decision system for olfactory reception exists, and this system may extrapolate to other insect species, as Ir75q1 and Ir75q2 are commonly expressed in many insect families.

neuroscience↗