SMART: On-Site Rapid Detection of Nucleic Acid from Plants, Animals, and Microorganisms in under 25 Minutes.

The rapid on-site nucleic acid detection method is urgently required in many fields. In this study, we report a portable and highly integrated device for DNA detection that combines ultrafast DNA adsorption and rapid DNA amplification. The device, known as silicon film mediated recombinase polymerase amplification (RPA) for nucleic acid detection (SMART), can detect target DNA in less than 25 min from plants, animals, and microbes. Utilizing SMART, transgenic maize was rapidly detected with high selectivity and sensitivity. The sensitivity threshold of the SMART for transgenic maize genomic DNA was 50 copies. The detection results of genuine samples containing plants, animals, and microbes by SMART were consistent with the conventional polymerase chain reaction (PCR) method, demonstrating the high robustness of SMART. Additionally, SMART does not require expensive equipment and is fast, affordable, and user-friendly, making it suited for the broad-scale on-site detection of nucleic acids.

A Fast, Visual, and Instrument-free Platform Involving Rapid DNA Extraction, Chemical Heating, and Recombinase Aided Amplification for On-Site Nucleic Acid Detection.

The nucleic acid-based technique has been widely utilized in many fields including for on-site detection. However, traditional molecular detection techniques encounter limitations like relying on instruments, time consuming or complex operation, and cannot meet the demands of on-site testing. In this study, a rapid DNA extraction method (RDEM), recombinase aided amplification (RAA), and chemical heating packet (CHP) are integrated and termed as RRC platform for on-site detection of nucleic acid. For demonstration purposes, SHZD32-1 (a new transgenic soybean line from China) was detected using the novel platform to demonstrate its feasibility and capability for on-site detection. Using the RDEM, high-quality DNA appropriate for molecular detection was quickly extracted in 3-5 min. The heat energy generated by CHP was met the temperature requirements of RAA. Using the RRC platform, the whole detection process can be accomplished within only 30 min, and the results can be visually detected with glasses under blue light. No special or expensive instrument was needed for the detection process. This study provides a novel approach for on-site detection of nucleic acids besides providing valuable insight on related future research.

[Establishment of a field visual detection method for genetically modified maize 'Shuangkang'12-5 by fluorescence RPA].

The genetically modified (GM) maize 'Shuangkang'12-5 has good insect resistance and herbicide tolerance, which is one of the first series of GM maizes obtained a safety certificate in China, and it has broad application prospect in the future. This study established an on-site rapid detection method for GM 'Shuangkang'12-5 based on recombinase polymerase amplification (RPA) technology, which primes and probe were designed according to the specific flank sequence. Then the best combination of primers and probe was obtained through a screeing process. The amplification results of fluorescence RPA can be directly visualized under blue light. The results showed that the visual detection system of GM 'Shuangkang'12-5 with high specificity, and the detection sensitivity of the method could reached 10 copies. Further research found that the RPA amplification system had a wide range of temperature (34℃-46℃). According to this property, the common self-heating warm pastes on the market were used replace the traditional heating instruments to stimulate the RPA.The results showed that the self-heating warm paste meets the temperature requirement of the RPA system. Finally, we combined the self-heating warm pastes with the RPA visual detection system to conduct on-site detection of GM 'Shuangkang'12-5, and compared the results with the detection results of qPCR. The detection showed that the results of on-site visual detection method established in this study were consistent with the detection results of the qPCR. Moreover, the visual detection method was more shorter in time and the final detection result was clear and easy to distinguish. The rapid on-site visual detection method for GM 'Shuangkang' 12-5 established in this study has high specificity, high sensitivity and convenience. It not only meets the needs of on-site rapid detection of GM 'Shuangkang'12-5, but also provides highlight for the development of other on-site rapid detection methods.

Response surface methodology to design a selective co-enrichment broth of Escherichia coli, Salmonella spp. and Staphylococcus aureus for simultaneous detection by multiplex PCR.

Escherichia coli, Salmonella spp. and Staphylococcus aureus are frequent co-visitors of contaminated foods to cause food-borne diseases. To achieve rapid detection of three organisms by multiplex PCR, a selective co-enrichment broth was considered to design using response surface methodology (RSM) in this work. NaCl, LiCl and KSCN as selective bacterial inhibitors were selected to optimize their concentrations for a matched composition of bacterial biomass with uniform amplification of three targets. Central composite design was employed to collect the data and fit the responses. Three quadratic polynomial models were derived by computer simulation. A statistical analysis was carried out to explore the effects of the variables on the composition of bacterial biomass and PCR amplification yields. In the end, a novel broth (ESS-3 broth) of NaCl 1.60%, LiCl 0.70%, KSCN 0.10% was formulated to allow co-enrichment of the target pathogens and suppress growth of some non-target pathogens. The simultaneous detection of E. coli, Salmonella spp. and S. aureus was developed on a rapid, convenient and sensitive method consisting of selective co-enrichment in ESS-3 broth, DNA extraction with the boiling method and robust test by multiplex PCR. Our work provided broader application of RSM for the simultaneous detection of other combinations of multiple pathogens.

[Molecular characteristics and specific PCR detection of transgenic rice containing Cry1Ab].

Bt01 is a new type of rice that has been genetically modified to express Cry1Abprotein. This study confirmed that Cry1Abwas inserted into Bt01 as a single copy using Southern blotting analysis. TAIL-PCR method was further used to obtain its insertion site information. Specific PCR primers and TaqMan probes were designed based on the 5'-integration junction sequence of transgenic rice Bt01. The results showed that the limit of detection (LOD) was ten copies in qualitative PCR. The quantitative PCR assay showed that the LOD was five copies, and the limit of quantification (LOQ) was ten cop-ies. In addition, the accuracy of the established quantitative PCR was verified by detecting two samples containing 3% and 0.5%Bt01, respectively. The quantitative PCR analysis showed the results were 2.7% and 0.47%, respectively.The above results indicated that the event-specific PCR methods developed have high specificity and good sensitivity, which could be effective methods for identifying and testing the genetically modified Bt01 rice.

[Construction of vectors for expression of cleavable tandem repeat Thanatin fusion protein in plants].

Thanatin, a 21-residue antimicrobial peptide, is an inducible insect peptide with a broad range of activity against bacteria and fungi. It can improve the expression level of the antimicrobial peptide in plants to express the peptide as tandem repeat fusion protein containing multiple Thanatin copies. However, the fusion protein has no antimicrobial activity. To make the fusion protein automatically break into single Thanatin unit with antimicrobial activity, the fused Thanatin was spaced by a linker peptide, which was cleavable in vivo. The soybean (Glysine max L.) chitinase signal peptide was fused to the N end of the fusion protein to induce the antimicrobial peptide accumulated in intercellular space. To construct the vectors for expression of the fusion protein, the overlapped primers were used to clone the antimicrobial peptide gene and the co-adhesive end restriction and ligation strategy was used to add the repeat unit one by one. Vectors containing 1 to 5 repeat units of Thanatin were constructed respectively. These vectors were being used to transform plants to improve plant disease resistance.

Activation of conventional PKC isoforms increases expression of the pro-apoptotic protein Bad and TRAIL receptors.

BACKGROUND: Pancreatic cancer is a leading cause of cancer death worldwide; current treatment options have been ineffective in prolonging survival. Agents that target specific signaling pathways (e.g., protein kinase C [PKC]) may regulate apoptotic gene expression rendering resistant cancers sensitive to the effects of other chemotherapeutic drugs. The purpose of our study was to assess the effect of PKC stimulation on apoptotic gene expression in pancreatic cancer cells. METHODS: The human pancreatic cancer cell line, PANC-1, was treated with PKC-stimulating agents, phorbol 12-myristate 13-acetate (PMA) or bryostatin-1, and analyzed for expression of apoptosis-related genes. RESULTS: Both PMA and bryostatin-1 induced expression of the pro-apoptotic gene Bad in a dose dependent fashion. The expression of Bad was blocked by the PKC inhibitors GF109203x, Gö6983, and Ro-31-8220, suggesting a role for the conventional isoforms of PKC. In addition, treatment with the MEK inhibitors PD98059 or UO126 reduced PMA-mediated induction of Bad gene expression. PMA also increased the expression of TRAIL receptors DR4 and DR5; this expression was inhibited by the PKC inhibitors GF109203x, Gö6983, and Ro-31-8220 and the MEK inhibitor UO126, suggesting a role for conventional PKC isoforms and MEK in the regulation of TRAIL receptor expression. CONCLUSIONS: PKC stimulation in PANC-1 cells increases expression of the pro-apoptotic gene Bad and the TRAIL receptors, DR4 and DR5, through both conventional PKC- and MEK-dependent pathways. Agents that stimulate PKC may sensitize pancreatic cancer cells to apoptosis and provide a potential adjuvant therapy for the treatment of chemoresistant pancreatic cancers.