RESUMO
Metarhizium spp. have emerged as an alternative to chemical pesticides for protecting crops from insect pest. Here, we investigated midgut microbial community and metabolites of Spodoptera litura at three different timepoints after infection with Metarhizium flavoviride. The innate immune system of S. litura was activated with levels of polyphenol oxidase, carboxylesterase, multifunctional oxidase, and glutathione S-transferase activity significantly increasing. Exposure to the fungal pathogen also altered bacterial abundance and diversity in host's midgut, and these changes varied depending on the time elapsed since exposure. We identified more operational taxonomic units in the treated samples as compared to the control samples at all tested time points. A total of 372 metabolites were identified, and 88, 149, and 142 differentially accumulated metabolites (DAMs) were identified between the treatment and control groups at 3 timepoints after treatment, respectively. Based on the changes of DAMs in response to M. flavoviride infection at different timepoints and significantly enriched KEGG pathways, we speculated that "tyrosine metabolism," "galactose metabolism," "ATP-binding cassette transporters," "neuroactive ligand-receptor interaction," "purine metabolism," "arginine and proline metabolism," "beta-alanine metabolism," "lysosome," and "carbon metabolism" may participate in the metabolic-level defense response. An integrated pathway-level analysis of the 16S-rDNA and metabolomic data illustrated the connections and interdependencies between the metabolic responses of S. litura and the midgut microorganisms to M. flavoviride infection. This work emphasizes the value of integrated analyses of insect-pathogen interactions, provides a framework for future studies of critical microorganisms and metabolic determinants of these interactions, establishes a theoretical basis for the sustainable use of M. flavoviride.
RESUMO
OBJECTIVE@#To exlpore the eff ect of depsides salts from Salvia miltiorrhiza on human hepatoma cell line SMMC-7721 xenograft tumors and the possible mechanisms.@*METHODS@#A total of 36 nude mice were divided into 6 groups: A model group, a negative control group, a positive control group, and 3 treatment groups at low, middle or high dose (n=6). The tumor model of nude mice was given depsides salts at a dose of 10, 20 or 50 mg/kg every 3 day for 16 days. Then samples of subcutaneous tumors in nude mice were collected. The morphological changes of tumor samples were observed by HE staining and the expression of vascular endothelial growth factor (VEGF) and the tumor antigen Ki67 was detected by immunohistochemical method.@*RESULTS@#The tumor growth was inhibited by all doses of depsides salts. The morphology of tumors was shrinkage, broken and irregularly arranged compared with the tumors in the model group and the negative control group. Morphological changes were more obvious in tumors with treatment at high dose. Expression of VEGF and Ki67 in treatment groups and the positive control group were lower than that in the model group and the negative control group, with a significant difference (P<0.05).@*CONCLUSION@#Depsides salts from Salvia miltiorrhiza can inhibit the growth of human hepatoma cell line SMMC-7721 tumor in nude mice, which is related to the inhibition of Ki67 and VEGF.