Silver nanoparticles have mainly been studied for their antimicrobial potential against bacteria, but have also proven to be active against several types of viruses, even against pebrine as well. Methods: Petri dishes...Silver nanoparticles have mainly been studied for their antimicrobial potential against bacteria, but have also proven to be active against several types of viruses, even against pebrine as well. Methods: Petri dishes and transmission electronic microscope were applied to observe silver nanoparticles against bacteria strains and nuclear polyhedral viruses (NPV) and cytoplasmic polyhedral viruses (CPV). For biological test, 108 CFU/mL NPV with strong pathogenicity, and the NPV samples treated with 1:100 ratio of “Sumerian Silver” for 8 hrs were sprayed on the mulberry leaves, respectively, for silkworm rearing. Conclusion: Silver nanoparticle solution showed a strong bactericidal effect against both G+ and G﹣bacterial pathogenic strains from Bombyx mori and mulberry. Under transmission electronic microscope (TEM), Bacillus sp. Samples showed light particles in the cells when treated with silver nanoparticles, in contrast, untreated samples showed homogeneity contents. Further, NPV particles showed no significant differences between treated and untreated samples, but CPV showed strong effects that almost all CPV were collapsed. For biological test, “Sumerian Silver” treated NPV showed no diseased silkworm but nearly all silkworms were dead with no treatment. It seems like that silver nanoparticles were proved to be more effective against CPV than that of NPV. The significant differences between two antivirus or virucidal mechanism should be greatly aroused the scientific interest.展开更多
The antifungal peptides, drosomycin （Drs） and its isoform drosomycin-like C （Drs-lC） from Drosophila melanogaster and Thanatin from Podisus maculiventris, have potent activity with broad spectrum against filamento...The antifungal peptides, drosomycin （Drs） and its isoform drosomycin-like C （Drs-lC） from Drosophila melanogaster and Thanatin from Podisus maculiventris, have potent activity with broad spectrum against filamentous fungi. Secretive expression of these genes in yeasts makes it possible to utilize the supernatants of yeast culture as protective reagents on fruit, vegetable, food and other agricultural products. So the study of effective secretion by yeast expression system is of great importance. Three genes, Drs, Drs-lC, and Thanatin, were cloned into pPICZαA and the recombinant vectors, pPICZαA-Drs, pPICZαA-Drs-lC, and pPICZαA-Thanatin were transformed into Pichia pastoris by the electric transfer method. The recombinant P. pastoris, which was screened by phenotype selection and PCR amplification, was induced to express antifungal peptide by methanol. The expressive products of the three recombinants showed antifungal activity against 5 out of 6 test fungi strains, and the products of Thanatin also had strong activity against the tested bacteria. The three antifungal peptide genes, Drs, Drs-lC, and Thanatin, were constructed into yeast P. pastoris. The expressed peptides were successfully secreted into the culture medium and exhibited potent activities against the test strains.展开更多
One antibacterial activity fraction from an immunized dipteran insect, Bactrocera dorsalis, was isolated and purified by prepurification, ion-exchange chromatography, gel filtration chromatography and reverse-phase hi...One antibacterial activity fraction from an immunized dipteran insect, Bactrocera dorsalis, was isolated and purified by prepurification, ion-exchange chromatography, gel filtration chromatography and reverse-phase high performance liquid chromatography （HPLC）. The final purified fraction was checked on the Smart system HPLC and was judged as a pure fraction. The results of physical and biological analysis revealed that this fraction is heat stable and showed strong activities against Gram-positive bacterial growth. It possesses antibicrobial peptide properties and is worth further investigation.展开更多
文摘Silver nanoparticles have mainly been studied for their antimicrobial potential against bacteria, but have also proven to be active against several types of viruses, even against pebrine as well. Methods: Petri dishes and transmission electronic microscope were applied to observe silver nanoparticles against bacteria strains and nuclear polyhedral viruses (NPV) and cytoplasmic polyhedral viruses (CPV). For biological test, 108 CFU/mL NPV with strong pathogenicity, and the NPV samples treated with 1:100 ratio of “Sumerian Silver” for 8 hrs were sprayed on the mulberry leaves, respectively, for silkworm rearing. Conclusion: Silver nanoparticle solution showed a strong bactericidal effect against both G+ and G﹣bacterial pathogenic strains from Bombyx mori and mulberry. Under transmission electronic microscope (TEM), Bacillus sp. Samples showed light particles in the cells when treated with silver nanoparticles, in contrast, untreated samples showed homogeneity contents. Further, NPV particles showed no significant differences between treated and untreated samples, but CPV showed strong effects that almost all CPV were collapsed. For biological test, “Sumerian Silver” treated NPV showed no diseased silkworm but nearly all silkworms were dead with no treatment. It seems like that silver nanoparticles were proved to be more effective against CPV than that of NPV. The significant differences between two antivirus or virucidal mechanism should be greatly aroused the scientific interest.
基金the grants from the National Basic Research Program of Ministry of Science and Technology, China （973 Program, 2005CB 121000） the Science and Technology Project of Guangdong Province, China （2003C104042） the Natural Science Foundation of Guangdong Province, China （032256, 04020553）.
文摘The antifungal peptides, drosomycin （Drs） and its isoform drosomycin-like C （Drs-lC） from Drosophila melanogaster and Thanatin from Podisus maculiventris, have potent activity with broad spectrum against filamentous fungi. Secretive expression of these genes in yeasts makes it possible to utilize the supernatants of yeast culture as protective reagents on fruit, vegetable, food and other agricultural products. So the study of effective secretion by yeast expression system is of great importance. Three genes, Drs, Drs-lC, and Thanatin, were cloned into pPICZαA and the recombinant vectors, pPICZαA-Drs, pPICZαA-Drs-lC, and pPICZαA-Thanatin were transformed into Pichia pastoris by the electric transfer method. The recombinant P. pastoris, which was screened by phenotype selection and PCR amplification, was induced to express antifungal peptide by methanol. The expressive products of the three recombinants showed antifungal activity against 5 out of 6 test fungi strains, and the products of Thanatin also had strong activity against the tested bacteria. The three antifungal peptide genes, Drs, Drs-lC, and Thanatin, were constructed into yeast P. pastoris. The expressed peptides were successfully secreted into the culture medium and exhibited potent activities against the test strains.
基金Acknowledgments We thank Prof. X.-F. Pang, late Academician of Chinese Academy of Science, for his support in getting this project started. We also thank Prof. Yamakawa （National of Institute of Sericultural and Entomological Science, Japan） for analyzing the purity of the final purified fraction. We thank Dr H. Ma for his suggestions on this project and reading our manuscript. This work was supported partly by the Natural Science Foundation of Guangdong Province （032256）, the National Basic Research Program of China under grant 2005CB121000 and the National Natural Science Foundation （30370716）.
文摘One antibacterial activity fraction from an immunized dipteran insect, Bactrocera dorsalis, was isolated and purified by prepurification, ion-exchange chromatography, gel filtration chromatography and reverse-phase high performance liquid chromatography （HPLC）. The final purified fraction was checked on the Smart system HPLC and was judged as a pure fraction. The results of physical and biological analysis revealed that this fraction is heat stable and showed strong activities against Gram-positive bacterial growth. It possesses antibicrobial peptide properties and is worth further investigation.
