ISOLATION AND FUNCTIONAL ANALYSIS OF McMenA,A GENE ENCODING A 1,4‐DIHYDROXY‐2‐NAPHTHOATE OCTAPRENYLTRANSFERASE IN Mylabris cichorii

Cantharidin is a biomolecule with a role in host defense that can also be used as an anticancer drug. The in vivo biosynthetic pathway for cantharidin has been the subject of debate for several decades and the mechanism is not yet completely understood. To study the biosynthetic pathway of cantharidin in blister beetles, Mylabris cichori, a full‐length MenA (McMenA) cDNA was cloned based on the partial sequence of the MenA gene from a suppression subtractive hybridization (SSH) library of male and female adult M. cichorii. The cDNA was 1264 base pairs (bp) with an open reading frame of 1026 bp nucleotides encoding a 341 amino acid protein. Analysis of the McMenA amino acid sequence showed that the aspartate rich motif N/DDxxD represented binding sites for prenyl diphosphate via a Mg²⁺ ion. Phylogenetic analysis showed that McMenA was most closely related to MenA of Tribolium castaneum, and the amino acid sequence similarity was 86%. The expression pattern of McMenA in adults was analyzed using RT‐qPCR, and we found that the highest expression of McMenA occurred during 22–25 days in the sex‐separate breeding males, while the lowest expression occurred in females at the same time. Injection with a specific double‐strand RNA (dsRNA) of McMenA led to a significant reduction of McMenA mRNA levels after 24 h. Cantharidin and ATP concentrations dropped around the same time. Together, our data showed that the McMenA gene might be involved in cantharidin biosynthesis.     

芫菁斑蝥素对几种动物蛋白磷酸酶2A的抑制作用

研究斑蝥素对马、兔、猪、鸡、眼斑芫菁Mylabris cichorii(L.)等几种动物体内PP2A的抑制作用。将斑蝥素作用于马、兔、猪、鸡、眼斑芫菁等几种动物体内的PP2A,采用蛋白磷酸酶抑制法-比色法测定斑蝥素对PP2A的抑制率。斑蝥素对马、兔、猪等哺乳动物体内的PP2A有明显的抑制作用,IC50分别为0.07、0.12、0.23 g/L;斑蝥素对鸡体内的PP2A有一定的抑制作用,而对于眼斑芫菁体内PP2A抑制作用不明显。马、兔、猪体内的PP2A对斑蝥素很敏感,而鸡和眼斑芫菁体内的PP2A对斑蝥素较不敏感。     

Enhanced toxicity of Cry2Ab with cantharidin and its analogues on Mythimna separata

The oriental armyworm, Mythimna separata Walker (Lepidoptera: Noctuidae), is a severe pest of graminaceous crops in Asia and Australia. In this study, we investigated the impacts of Cry2Ab, cantharidin and its analogues (cantharidin‐23 and cantharidin‐24) on M. separata growth, hydrolytic enzymes and detoxifying enzymes. Differences in weight gain and enzyme activities among all treatments were observed. Larval and pupal weight gain and hydrolytic enzyme activities declined when larvae were treated with Cry2Ab, cantharidin and its analogues, individually or in combination. The combination of Cry2Ab and cantharidin or cantharidin‐24 had a markedly adverse effect on larval weight gain. Alkaline phosphatase and acid phosphatase were inhibited, whereas glutathione S‐transferase was upregulated in all treatments with sublethal doses. The maximum reduction in alkaline phosphatase activity and increase in glutathione S‐transferase activity occurred after the larvae were treated with a combination of Cry2Ab and cantharidin‐24 over 48 h. The results suggest that the compositions of Cry2Ab, cantharidin and cantharidin‐24 have a potential use in pest management.     

Quality Evaluation of Traditional Chinese Medicine Mylabris Based on Heavy Metal Risk Assessment and Analysis of Pharmacological Component Contents

As a highly representative traditional Chinese anti-tumor medicinal material, the biomass of Mylabris is collected from the wild. However, the living environments of Mylabris is differ, so Mylabris may be contaminated by heavy metal pollution depending on the environment. These environments may also affect the amount of biosynthesis of its medicinal ingredient, cantharidin, there by affecting the quality of Mylabris. In this study, we determined the heavy metal content in Mylabris from different origins by using ICP-MS, evaluated the risk posed by these heavy metals, and recommended theoretical maximum limits of heavy metals in medicinal Mylabris. The results show that the Cu content in Mylabris is substantially higher than that in Cr, As, Pb, Cd, and Hg. A quantitative risk assessment showed that Mylabris poses no noncarcinogenic risks. The results of the total carcinogenic risk value showed that origins S12 and S13 pose carcinogenic risk by Cr and As, and the rest of the origins were in the human-tolerable carcinogenic risk range. We found large differences in the cantharidin content in Mylabris from different origins. In general, the Mylabris from origins S2, S3 and S4 had a higher in vivo cantharidin content, which proved that the quality of the medicinal materials was higher here than in other production areas. Finally, we providing a reference for the quality evaluation of medicinal Mylabris materials.