An Antenna-Enriched Chemosensory Protein Plays Important Roles in the Perception of Host Plant Volatiles in Bactrocera dorsalis (Diptera: Tephritidae).

Olfaction plays indispensable roles in insect behavior such as host location, foraging, oviposition, and avoiding predators. Chemosensory proteins (CSPs) can discriminate the hydrophobic odorants and transfer them to the odorant receptors. Presently, CSPs have been identified in many insect species. However, their presence and functions remain unknown in Bactrocera dorsalis, a destructive and invasive insect pest in the fruit and vegetable industry. Here, we annotated eight CSP genes in the genome of B. dorsalis. The results of quantitative real-time polymerase chain reaction (RT-qPCR) showed that BdorCSP3 was highly expressed in the antennae. Molecular docking and in vitro binding assays showed that BdorCSP3 had a good binding ability to host volatiles methyl eugenol (ME, male-specific attractant) and ß-caryophyllene (potential female attractant). Subsequently, CRISPR/Cas9 was used to generate BdorCSP3-/- mutants. Electroantennograms (EAGs) and behavioral assays revealed that male mutants significantly reduced the preference for ME, while female mutants lost their oviposition preference to ß-caryophyllene. Our data indicated that BdorCSP3 played important roles in the perception of ME and ß-caryophyllene. The results not only expanded our knowledge of the olfaction perception mechanism of insect CSPs but also provided a potential molecular target for the control of B. dorsalis.

CRISPR-mediated mutagenesis of the odorant receptor co-receptor (Orco) gene disrupts olfaction-mediated behaviors in Bactrocera dorsalis.

Olfaction plays an essential role in insect behavior such as host location, foraging, mating, and oviposition. The odorant receptor co-receptor (Orco) is an obligatory odorant receptor and indispensable in odor perception. Here, we characterized the Orco gene from the oriental fruit fly, Bactrocera dorsalis (Hendel), a notorious agriculture pest. The olfactory deficiency mutants were generated by editing the BdorOrco gene using the CRISPR/Cas9 system. Electroantennograms (EAG) and olfactory preference assays confirmed that BdorOrco-/- mutant flies had reduced perception of methyl eugenol, ß-caryophyllene, and ethyl acetate. Oviposition bioassays showed that the eggs laid by BdorOrco-/- females mediated by benzothiazole and 1-octen-3-ol were significantly decreased. In addition, BdorOrco-/- mutant flies took a significantly longer time to locate the food source compared with wild type (WT) flies. Altogether, our data indicated that Orco is essential for multiple physiological processes in B. dorsalis, and it expands our understanding of the function of insect Orco.

Comparative transcriptomic analysis reveals female-biased olfactory genes potentially involved in plant volatile-mediated oviposition behavior of Bactrocera dorsalis.

BACKGROUND: Olfactory systems take on important tasks to distinguish salient information from a complex olfactory environment, such as locating hosts, mating, aggression, selecting oviposition sites, and avoiding predators. The olfactory system of an adult insect consists of two pairs of main olfactory appendages on the head, the antennae, and the palps, which are covered with sensilla. Benzothiazole and 1-octen-3-ol could elicit oviposition behavior in gravid B. dorsalis are regarded as oviposition stimulants. However, the mechanism for how B. dorsalis percepts benzothiazole and 1-octen-3-ol still remains unknown. RESULTS: We conducted a comparative analysis of the antennal transcriptomes in different genders of B. dorsalis using Illumina RNA sequencing (RNA-seq). We identified a total of 1571 differentially expressed genes (DEGs) among the two sexes, including 450 female-biased genes and 1121 male-biased genes. Among these DEGs, we screened out 24 olfaction-related genes and validated them by qRT-PCR. The expression patterns of these genes in different body parts were further determined. In addition, we detected the expression profiles of the screened female-biased chemosensory genes in virgin and mated female flies. Furthermore, the oviposition stimulants-induced expression profilings were used to identify chemosensory genes potentially responsible for benzothiazole and 1-octen-3-ol perception in this fly. CONCLUSIONS: The results from this study provided fundamental data of chemosensory DEGs in the B. dorsalis antenna. The odorant exposure assays we employed lay a solid foundation for the further research regarding the molecular mechanism of benzothiazole and 1-octen-3-ol mediated oviposition behavior in B. dorsalis.

Traditional Chinese medicine targeting cancer stem cells as an alternative treatment for hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a prevalent and highly malignant cancer throughout the world. Effective treatment of this disease is impeded by the high rate of metastasis, recurrence, and chemoresistance. Recent studies have revealed the close relationship between the malignant phenotype of HCC and cancer stem cells (CSCs). Therefore, CSC-targeted therapy is considered a promising strategy to eradicate HCC. Traditional Chinese medicine (TCM) can be effective in preventing recurrence and metastasis of some advanced HCC. A growing amount of literature has discovered that extracts or compounds derived from TCM exert an anti-CSC effect. This review introduces some formulas and chemical compounds derived from TCMs that have been reported to inhibit CSCs of HCC; these TCM-related drugs may help to provide an alternative approach to help manage cancers, especially for HCC which has a great potential of metastasis, recurrence, and chemoresistance.