Strategies for exogenous RNA delivery in RNAi-mediated pest management / 生物工程学报

Plant diseases and insect pests threaten the safety of crop production greatly. Traditional methods for pest management are challenged by the problems such as environmental pollution, off-target effects, and resistance of pathogens and insects. New biotechnology-based strategies for pest control are expected to be developed. RNA interference (RNAi) is an endogenous process of gene regulation, which has been widely used to study the gene functions in various organisms. In recent years, RNAi-based pest management has received increasing attention. The effective delivery of the exogenous interference RNA into the targets is a key step in RNAi-mediated plant diseases and pest control. Considerable advances were made on the mechanism of RNAi, and various RNA delivery systems were developed for efficient pest control. Here we review the latest advances on mechanisms and influencing factors of RNA delivery, summarize the strategies of exogenous RNA delivery in RNAi-mediated pest control, and highlight the advantages of nanoparticle complexes in dsRNA delivery.

The Risk of Wheat Blast in Rice-Wheat Co-Planting Regions in China: MoO Strains of Pyricularia oryzae Cause Typical Symptom and Host Reaction on Both Wheat Leaves and Spikes.

The Triticum pathotype of Magnaporthe oryzae (syn. Pyricularia oryzae) causes wheat blast, which has recently spread to Asia. To assess the potential risk of wheat blast in rice-wheat growing regions, we investigated the pathogenicity of 14 isolates of P. oryzae on 32 wheat cultivars, among which Oryzae pathotype of P. oryzae (MoO) isolates were completely avirulent on the wheat cultivars at 22°C but caused various degrees of infection 25°C. These reactions at 25°C were isolate and cultivar dependent, like race-cultivar specificity, which was also recognized at the heading stage and caused typical blast symptoms on spikes. Microscopic analyses indicated that a compatible MoO isolate produced appressoria and infection hyphae on wheat as on rice. When we compared transcriptomes in wheat-MoO interactions, the bulk of pathogen-related genes were upregulated or downregulated in compatible and incompatible patterns, but changes in gene transcription were more significant in a compatible pattern. These results indicate that temperature could influence the infection ratio of wheat with MoO, and some MoO strains could be potential pathogens that increase the risk of wheat blast outbreaks in wheat-rice growing regions with global warming. In addition, certain wheat cultivars exhibited resistance and are assumed to carry resistance-promoting genes to the MoO strains.

Novel guidance system assistance percutaneous pedicle screw placement for thoracolumbar vertebral fracture without nerve injury / 局解手术学杂志

Objective The aim of this study was to compare recent clinical efficacy between a novel guidance method for percutaneous pedicle screw placement and the conventional fluoroscopic method for long segments thoracolumbar vertebral fracture without nerve injury. Methods A total of 38 patients with thoracolumbar vertebral fracture in our hospital from September 2010 to December 2012 were divided into group A and group B.Eighteen patients in group A underwent 200 percutaneous pedicle screw fixation by conventional fluoroscopic meth-od.Twenty patients in group B underwent 210 percutaneous pedicle screw fixation by a novel guidance method.All the operation for 38 cases were performed by the same surgeon.The time of insertion,radiation exposure,and accuracy of the screw placement between the two groups were compared.The accuracy of screws was evaluated and graded by two consecutive postoperative CT of operation segment for two groups. Results The mean time for a single pedicle screw placement was (13.11 ±2.32)minutes in group A and (10.35 ±1.92)minutes in group B,respectively.The average radiation exposure was (8.11 ±1.15)s in group B and (13.07 ±2.06)s in group A respectively.The differ-ences were statistically significant for both screw placement and radiation exposure times (P 0.05).Conclusion The novel guidance system can significantly reduce the insertion time and radiation expo-sure for long segments percutaneous pedicle screw placement,which provides the same accuracy for screw placement compared with the con-ventional method.

Dual screening for targeted gene replacement mutant in Magnaporthe oryzae with GUS as negative marker / 生物工程学报

To improve the efficiency of targeted gene replacement (TGR), a dual screen (DS) system with gusA gene as negative selective marker (GUS-DS) was developed in Magnaporthe oryzae. First, we tested the endogenous beta-glucuronidase (GUS) activities of 78 fungal strains. All tested strains were GUS-, only with 3 exceptions. Whereas, after the gusA being introduced in, M. oryzae, Fusarium oxysporum and Colletotrichum lagenarium acquired high GUS activities. The gusA is thus usable as a selective maker in fungal species. With gusA as the negative marker, HPH gene as the positive marker, and the peroxisomal targeting signal receptor genes MGPEX5 and MGPEX7 as 2 instances of target genes, we established the GUS-DS system. After transformation, we collected the transformants from hygromycin B screen media and then tested the GUS activities of them. The GUS- ones were selected as potential mutants and checked in succession by PCR and Southern blotting to identify the true mutants and calculate the efficiency of GUS-DS. As a result, GUS-DS improved the screen efficiency for delta mgpex5 from 65.8% to 90.6%, and for delta mgpex7 from 31.2% to 82.8%. In addition, we established a multiple PCR (M-PCR) method for mutant confirmation. By amplifying the different regions at the targeted locus, M-PCR differentiated the wild type, the ectopic transformants and the mutants effectively and rapidly, and had the same reliability as Southern blotting. In conclusion, GUS-DS and M-PCR are useful tools to improve the efficiency of TGR and would be helpful for fungal genomics.

The chest radiological manifestation in psittacosis / 中华放射学杂志

Objective To summarize the cl inical characteristics and imaging features of psittacosis. Methods The clinical features and imaging appearances of 3 cases with acute psittacosis were retrospectively analyzed. The related literature was reviewed . Results The clinical manifestation of psittacosis was high fever in the patients. Physical findings included pulse-temperature dis sociation, localized lung crackles, hepatomegaly, and splenomegaly. Laboratory findings showed elevation of ESR in all cases, and liver dysfunction was present in 2 cases. The counts of white blood cells were normal, but the percent of ne utrophils might be increased. The chest X-ray and CT scan showed air-space co nsolidation and ground-glass attenuation in the lung, and miliary, nodular, or consolidated shadows were found in pathological areas. Pleural effusions were a lso present in 2 cases. Psittacosis was diagnosed from the history of exposure to infected parrots and elevation of the IgG and IgM titer for Chlamydia psittac i. Erythromycin was effective in all 3 patients. Conclusion Although the appearance of psittacosis on clinical findings and chest X-r ay and CT scan is not characteristic, psittacosis can be diagnosed with the comb ination of the history of exposure to infected parrots and laboratory findings. CT scan can reveal the focus earlier and accurately, and catching the imaging f eatures of psittacosis is helpful in differential diagnosis.