Identification and functional characterization of chemosensory genes in olfactory and taste organs of Spodoptera litura (Lepidoptera: Noctuidae)

The tobacco cutworm Spodoptera litura is one of the most destructive polyphagous crop pests.Olfaction and taste play a crucial role in its host plant selection and sexual communication,but the expression profile of chemosensory genes remains unclear.In this study,we identified 185 chemosensory genes from 7 organs in S.litura by transcriptome sequencing,of which 72 genes were published for the first time,including 27 odorant receptors(ORs),26 gustatory receptors(GRs),1 ionotropic receptor(IR),16 odorant-binding proteins(OBPs),and 2 chemosensory proteins(CSPs).Phylogenetic analyses revealed that ORs,IRs,OBPs,and sensory neuron membrane proteins(SNMPs)were mainly expressed in antennae and sequence-conserved among Noctuidae species.The most differentially expressed genes(DEGs)between sexes were ORs and OBPs,and no DEGs were found in GRs.GR transcripts were enriched in proboscis,and the expression of sugar receptors was the highest.Carbon dioxide receptors,sugar receptor-SliuGR6,and bitter GRs-SlituGR43 and SlituGR66 had higher sequence identities between Noctuidae species.CSPs were broadly expressed in various organs,and SlituCSP13 was a DEG in adult antennae.The functional analysis in the Drosophila OR67d expression system found that SlituOR50,a receptor highly expressed in female antennae,is selectively tuned to farnesyl acetate.The results provide a solid foundation for understanding the molecular mechanisms by which chemosensory genes operate to elicit behavioral responses in polyphagous insects.

Respiratory Control by Phox2b-expressing Neurons in a Locus Coeruleus–pre B?tzinger Complex Circuit

The locus coeruleus(LC) has been implicated in the control of breathing.Congenital central hypoventilation syndrome results from mutation of the paired-like homeobox 2 b(Phox2 b) gene that is expressed in LC neurons.The present study was designed to address whether stimulation of Phox2 b-expressing LC(Phox2 b~(LC)) neurons affects breathing and to reveal the putative circuit mechanism.A Cre-dependent viral vector encoding a Gqcoupled human M3 muscarinic receptor(hM3 Dq) was delivered into the LC of Phox2 b-Cre mice.The hM3 Dqtransduced neurons were pharmacologically activated while respiratory function was measured by plethysmography.We demonstrated that selective stimulation of Phox2 b~(LC) neurons significantly increased basal ventilation in conscious mice.Genetic ablation of these neurons markedly impaired hypercapnic ventilatory responses.Moreover,stimulation of Phox2 b~(LC) neurons enhanced the activity of preBotzinger complex neurons.Finally,axons of Phox2 b~(LC) neurons projected to the preBotzinger complex.Collectively,Phox2 b~(LC) neurons contribute to the control of breathing most likely via an LC-preBotzinger complex circuit.

Evolutionary ecology of chemosensation and its role in sensory drive

All behaviors of an organism are rooted in sensory processing of signals from its environment, and nat ural selection shapes sensory adaptations to ensure successful detection of cues that maximize fitness. Sensory drive, or divergent selection for efficient signal transmission among heterogeneous environ ments, has been a useful hypothesis for describing sensory adaptations, but its current scope has pri marily focused on visual and acoustic sensory modalities. Chemosensation, the most widespread sensory modality in animals that includes the senses of smell and taste, is characterized by rapid evolu tion and has been linked to sensory adaptations to new environments in numerous lineages. Yet, olfac tion and gustation have been largely underappreciated in light of the sensory drive hypothesis. Here, we examine why chemosensory systems have been overlooked and discuss the potential of chemo sensation to shed new insight on the sensory drive hypothesis and vice versa. We provide suggestions for developing a framework to better incorporate studies of chemosensory adaptation that have the po tential to shape a more complete, coherent, and holistic interpretation of the sensory drive.

Effects of DIMBOA on impulse discharges of maxillary lateral sensillum styloconicum of armyworm larvae

THE DIMBOA (2, 4-dihydroxy-7-methoxy-1, 4-benzoxazin-3-one), a secondary product present in corn plants, plays an important role in protecting the plant against the pest attack. DIMBOA is rich in seedlings of cereal crops, especially in maize. Many investigators demonstrated a linear relationship between the DIMBOA content in plant and the resistance of the plant to pest. Feng et al. (1992) summarized that the toxicity of DIMBOA is associated