从香蕉园或者其他果园的土壤中分离获得5株对香蕉枯萎病菌(Fusarium oxysporum f. sp.Cubense)具有抑制作用的拮抗菌,并对其抑菌效果和和机制进行了测定.结果表明,测试的5株拮抗菌d4、d5、d6、B3和p与香蕉枯萎病菌对峙培养5d后,在平板...从香蕉园或者其他果园的土壤中分离获得5株对香蕉枯萎病菌(Fusarium oxysporum f. sp.Cubense)具有抑制作用的拮抗菌,并对其抑菌效果和和机制进行了测定.结果表明,测试的5株拮抗菌d4、d5、d6、B3和p与香蕉枯萎病菌对峙培养5d后,在平板上产生明显的抑菌带,抑菌带宽度为16.5～20.5mm;培养10d后,仍然保持稳定的抑菌效果;5株拮抗菌发酵原液对孢子萌发具有显著的抑制作用,抑制率为90.49%～97.18%;拮抗菌对病菌的作用机制表现为对菌丝的消融、菌丝细胞的泡囊化、抑制病菌分生孢子的萌发、孢子芽管的扭曲.展开更多
Since its discovery a decade ago, microRNA has been identified as one of the major regulatory gene families in eukaryotic cells. Many functions of microRNAs have been revealed both in flora and fauna in recent years, ...Since its discovery a decade ago, microRNA has been identified as one of the major regulatory gene families in eukaryotic cells. Many functions of microRNAs have been revealed both in flora and fauna in recent years, but the transcriptional regulation of microRNA genes is not well-understood. In the present study, a series of primers were designed in the 2 000 nt upstream regions of porcine miR-181 and miR-1 and then the sequences were cloned into pGL3-basic vector to test their transcriptional activity. Dual-luciferase reporter assays showed that, the activity of 5＂-flanking sequence of miR-181 started on construct -51, decreasing with the length of the fragment up to -444. The upstream 590 bp confer maximal transcriptional activity and the basal promoter activity is located within the -82 to ＋16 bp region. For miR-1, the activity starts on construct -50, decreasing with the length of the fragment up to -1 254 in despite of a bit of fluctuation, and the basal promoter activity is located within the -50 to ＋47 bp region. Furthermore, some putative regulation elements of both miR-181 and miR-1 were located. In addition, tissue distribution revealed that miR-181 is expressed at a relatively low level.展开更多
We attempted to improve the activity of hTERT promoter by fusing the vascular endothelial growth factor （VEGF） enhancer. To determine the potential as cancer specific promoters, we measured the reporter gene transfe...We attempted to improve the activity of hTERT promoter by fusing the vascular endothelial growth factor （VEGF） enhancer. To determine the potential as cancer specific promoters, we measured the reporter gene transfection assay driven by the hTERT promoter and the VEGF enhancer in human cancer cells. We found that the hTERT promoter containing VEGF enhancer conferred strong expression of the reporter gene only in different cancer cell lines but not in normal human cells. Retrovirus vector expressing HSV-TK controlled by the hTERT promoter and the VEGF enhancer was constructed. A549 cells infected with LN-enh-hT-TK was significantly suppressed and induced to apoptosis more than those infected with LN-hT-TK. The apoptosis ratio ofA549 cell infected with two kinds of retrovirus cell with GCV in lower concentration is 20.94% and 50.7%. It suggested that there is significant differentiation between the assay groups. Our results demonstrated the possible application of hTERT promoter and the VEGF enhancer in targeted cancer gene therapy.展开更多
The direct negative impact of the transcriptional activity of one component on the second one in c/s is referred to as transcriptional interference （TI）. U6 is a type III RNA polymerase III promoter commonly used fo...The direct negative impact of the transcriptional activity of one component on the second one in c/s is referred to as transcriptional interference （TI）. U6 is a type III RNA polymerase III promoter commonly used for driving small hairpin RNA （shRNA） expression in vector-based RNAi. In the design and construction of viral vectors, multiple transcription units may be arranged in close proximity in a space-limited vector. Determining if U6 promoter activity can be affected by TI is critical for the expression of target shRNA in gene therapy or loss-of-function studies. In this research, we designed and implemented a modified retroviral system where shRNA and exogenous gene expressions were driven by two independent transcriptional units. We arranged U6 promoter driving .shRNA expression and UbiC promoter in two promoter arrangements. In primary macrophages, we found U6 promoter activity was inhibited by UbiC promoter when in the divergent arrangement but not in tandem. In contrast, PKG promoter had no such negative impact. Instead of enhancing U6 promoter activity, CMV enhancer had significant negative impact on U6 promoter activity in the presence of UbiC promoter. Our results indicate that U6 promoter activity can be affected by TI in a proximal promoter-specific and arrange- ment-dependent manner.展开更多
文摘从香蕉园或者其他果园的土壤中分离获得5株对香蕉枯萎病菌(Fusarium oxysporum f. sp.Cubense)具有抑制作用的拮抗菌,并对其抑菌效果和和机制进行了测定.结果表明,测试的5株拮抗菌d4、d5、d6、B3和p与香蕉枯萎病菌对峙培养5d后,在平板上产生明显的抑菌带,抑菌带宽度为16.5～20.5mm;培养10d后,仍然保持稳定的抑菌效果;5株拮抗菌发酵原液对孢子萌发具有显著的抑制作用,抑制率为90.49%～97.18%;拮抗菌对病菌的作用机制表现为对菌丝的消融、菌丝细胞的泡囊化、抑制病菌分生孢子的萌发、孢子芽管的扭曲.
基金funded by the National Natural Science Foundation of China (31000996)the International Foundation for Science (B/4534-1)the Specialized Research Fund for the Doctoral Program of Higher Education, China(200805041012)
文摘Since its discovery a decade ago, microRNA has been identified as one of the major regulatory gene families in eukaryotic cells. Many functions of microRNAs have been revealed both in flora and fauna in recent years, but the transcriptional regulation of microRNA genes is not well-understood. In the present study, a series of primers were designed in the 2 000 nt upstream regions of porcine miR-181 and miR-1 and then the sequences were cloned into pGL3-basic vector to test their transcriptional activity. Dual-luciferase reporter assays showed that, the activity of 5＂-flanking sequence of miR-181 started on construct -51, decreasing with the length of the fragment up to -444. The upstream 590 bp confer maximal transcriptional activity and the basal promoter activity is located within the -82 to ＋16 bp region. For miR-1, the activity starts on construct -50, decreasing with the length of the fragment up to -1 254 in despite of a bit of fluctuation, and the basal promoter activity is located within the -50 to ＋47 bp region. Furthermore, some putative regulation elements of both miR-181 and miR-1 were located. In addition, tissue distribution revealed that miR-181 is expressed at a relatively low level.
文摘We attempted to improve the activity of hTERT promoter by fusing the vascular endothelial growth factor （VEGF） enhancer. To determine the potential as cancer specific promoters, we measured the reporter gene transfection assay driven by the hTERT promoter and the VEGF enhancer in human cancer cells. We found that the hTERT promoter containing VEGF enhancer conferred strong expression of the reporter gene only in different cancer cell lines but not in normal human cells. Retrovirus vector expressing HSV-TK controlled by the hTERT promoter and the VEGF enhancer was constructed. A549 cells infected with LN-enh-hT-TK was significantly suppressed and induced to apoptosis more than those infected with LN-hT-TK. The apoptosis ratio ofA549 cell infected with two kinds of retrovirus cell with GCV in lower concentration is 20.94% and 50.7%. It suggested that there is significant differentiation between the assay groups. Our results demonstrated the possible application of hTERT promoter and the VEGF enhancer in targeted cancer gene therapy.
文摘The direct negative impact of the transcriptional activity of one component on the second one in c/s is referred to as transcriptional interference （TI）. U6 is a type III RNA polymerase III promoter commonly used for driving small hairpin RNA （shRNA） expression in vector-based RNAi. In the design and construction of viral vectors, multiple transcription units may be arranged in close proximity in a space-limited vector. Determining if U6 promoter activity can be affected by TI is critical for the expression of target shRNA in gene therapy or loss-of-function studies. In this research, we designed and implemented a modified retroviral system where shRNA and exogenous gene expressions were driven by two independent transcriptional units. We arranged U6 promoter driving .shRNA expression and UbiC promoter in two promoter arrangements. In primary macrophages, we found U6 promoter activity was inhibited by UbiC promoter when in the divergent arrangement but not in tandem. In contrast, PKG promoter had no such negative impact. Instead of enhancing U6 promoter activity, CMV enhancer had significant negative impact on U6 promoter activity in the presence of UbiC promoter. Our results indicate that U6 promoter activity can be affected by TI in a proximal promoter-specific and arrange- ment-dependent manner.
