Du L.,Agricultural University of Hebei
Wei sheng wu xue bao = Acta microbiologica Sinica | Year: 2011
To construct and characterize a sigK gene disruption mutant of Bacillus thuringiensis and to study influence of sigK gene disruption on the activation of cry3A gene promoter. We constructed the sigK gene disruption mutant HD delta sigK by inserting kanamycin resistance gene via homologous recombination. Scanning electron microscopy and spore formation analysis were used to detect the abilities of sporulation and crystal protein formation of both the mutant and the wild-type strain. SDS-PAGE analysis was used to detect the expression of crystal protein. Beta-galactosidase assay of cry3A'-lacZ gene fusion was performed to analyze the influence of sigK gene disruption on the activation of cry3A promoter. The growth curve showed that mutant grew slowly in late stationary phase compared to the wild-type strain. Scanning electron microscopy and spore formation analysis indicated that no spore was produced in sigK disruption mutant. SDS-PAGE results exhibited that the expression of cry gene was significantly decreased in the mutant. Beta-galactosidase assay showed that the activation of cry3A promoter was stronger in the mutant than that in HD-73 during late stationary phase, but the disruption of sigK gene had no significant influence on the production of Cry1Ac which was initiated by cry3A gene promoter. These results indicated that sigK gene was one of the essential genes during the sporulation of Bacillus thuringiensis, and influenced the expression of crystal protein. The expression of crystal protein which was initiated by cry3A gene promoter in sigK disruption mutant could be used to develop high-efficiency and safe biological pesticides.
Liu X.,Agricultural University of Hebei
Wei sheng wu xue bao = Acta microbiologica Sinica | Year: 2011
Our study is to analyse the coinfection effects of porcine circovirus type 2 (PCV2) and porcine parvovirus (PPV) in vivo on phagocytosis and interferon mRNA expression level of porcine alveolar macrophages (PAM). Forty-eight 5-week-old healthy piglets were divided randomly into 4 groups of 12 (PCV2, PPV, PCV2/PPV and the control groups). The piglets in PCV2 group were inoculated oronasally with 3 mL of porcine circovirus type2 (PCV2, 10(5.61) TCID50/0.1 mL), PPV group with 3 mL of porcine parvovirus (PPV, 10(6.69) TCID50/0.1 mL), PCV2/PPV group with 3 mL of PCV2 and 3 mL of PPV and the control group with 3 mL of cell culture medium, respectively. Three piglets from each group were sacrificed randomly on 3, 7, 14 and 35 day post infection (dpi) and porcine alveolar macrophages (PAM) were collected to detect viability, phagocytotic capabilities and alpha1- and gamma-interferon (IFN-alpha1 and IFN-gamma) mRNA levels of PAM. The viabilities of PAM from PCV2 group and PCV2/PPV group became weaker than that of control group during the period of 3 - 14 dpi but they were similar to that of control group on 35 dpi; there was no significant difference between the viability of PCV2/PPV group and that of PCV2 group (P > 0.05). The phagocytotic capabilities of PAM from three virus infection groups were lower than that of control group (P < 0.01), among which that of PCV2/PPV group descended more drastically. IFN-alpha1 and IFN-gamma mRNA levels in PAM from PCV2/PPV group were significantly lower than those of PCV2, PPV and control groups (P < 0.01). PCV2/PPV co-infection did not cause further decline of PAM viability but strongly weakened phagocytosis and constantly lowered IFN (IFN-alpha1 and IFN-gamma) mRNA expression levels of PAM.
Huang Y.,CAS Research Center for Eco Environmental Sciences |
Chen Z.,CAS Research Center for Eco Environmental Sciences |
Liu W.,Agricultural University of Hebei
Plant and Soil | Year: 2012
Background and Aims: Characteristically baseline levels of Sb in the environment are low, but problematic local elevation trends arise from anthropogenic activities such as mining and incineration. Arsenic (analog of Sb) accumulation by rice can be reduced by iron (Fe) plaque. A hydroponic experiment was conducted to investigate whether Fe plaque could reduce the uptake and translocation of different Sb species in different rice cultivars. Methods: After Fe plaque on rice roots was induced in solution containing 0, 0.2, 0.4, 0.7, 1.2, 2.0 mM Fe 2+ for 24 h, seedlings were transferred into nutrient solution with 20 μM Sb(V) or Sb(III) for 3 d. Results: About 60-80% (Sb(III) treatment) and 40-60% (Sb(V) treatment) of the total Sb accumulated in Fe plaque. There was a significant correlation between the concentrations of Sb and Fe on the root surface. A similar relationship was observed in roots and shoots. Cultivar (Jiahua 1) formed the most Fe plaque, had the highest Fe associated Sb sequestration but the lowest Sb concentration in the root interior. Conclusions: Fe plaque may act as a 'buffer' for Sb(V) and Sb(III) in the rhizosphere, and cultivars played an important role in the different species Sb uptake and translocation. © 2011 Springer Science+Business Media B.V.
Pan H.,Agricultural University of Hebei
Wei sheng wu xue bao = Acta microbiologica Sinica | Year: 2012
To investigate the effects of canine parvovirus (CPV) non-structural protein-1 (NS1) on the cell apoptosis induced by CPV and preliminarily explore the mechanism of CPV-induced apoptosis. First, the NS1 gene was amplified by PCR from CPV genomic DNA and subcloned into pcDNA3. 1A vector to generate NS1 eukaryotic expression vector pcDNA-NS1. To verify whether pcDNA-NS1 vector can mediate NS1 expression in eukaryotic cells, the human embryo kideny (HEK) 293FT cells were used to transiently express the recombinant NS1. The effects of NS1 on CPV-induced apoptosis were investigated by infecting the F81 host cells with CPV and transfecting the cells with NS1 vector. The apoptosis of the cells was detected by AnnexinV/PI double staining for phosphatidylserine externalization on membrane and by luminescence method for caspase-3/7 activities. The results show that the sequence of NS1 gene amplified was consistent with the GenBank. The NS1 expression vector was shown to be correct and could mediate NS1 expression in eukaryotic cells. The phosphatidylserine on outside of membrane was detected and the caspase-3/7 activities were increased in both CPV-infected cells and NS1-transfected cells. These results indicate that both CPV and NS1 protein can induce the apoptosis of the cells. CPV-induced apoptosis was closely related to its non-structural protein NS1.
Zhang K.,Agricultural University of Hebei
Applied Mechanics and Materials | Year: 2014
This paper introduces the working principle of remote access system based on SSL VPN in cloud computing. Meanwhile, it focuses on the operation principle of the SSL protocol and resource management. In addition, it analyses system characteristics such as https login, hardware signature certification and so on. At last, it puts forward some problems and solutions in actual use. © (2014) Trans Tech Publications, Switzerland.