Transferring foreign DNA into plant cells by biolistic and Agrobacterium _mediated methods may result in random integration of different copy numbers of the transgene, and different proportions of intact vs. rearra...Transferring foreign DNA into plant cells by biolistic and Agrobacterium _mediated methods may result in random integration of different copy numbers of the transgene, and different proportions of intact vs. rearranged copies of the transgene. This may, in turn, affect transgene expression levels. To test the above hypothesis, we first introduced the same plasmid, pAc1PG_CAM, into rice (Oryza sativa L.) calli separately by the biolistic method and by the Agrobacterium _mediated method. To show whether different plasmids may affect the results, we also introduced pTOK233 by the Agrobacterium _mediated method and pJPM44 by the biolistic method. Transgene expression of R0 plants was monitored by histochemical analysis of GUS activity. Transgene copy number was determined by Southern blot analysis after digesting genomic DNA with an enzyme that has a unique cutting site within the input plasmid. The total genomic DNA was also digested by a two_cut enzyme (the cuts are located at two sides of a given transgene expression cassette), followed by Southern blotting analysis, for determining the number of intact transgene expression cassettes. Our data showed that Agrobacterium _mediated transformation resulted in lower transgene copy number (average between 2.1 and 2.3) in transgenic rice plants, compared with those plants obtained by the biolistic method (average between 4.2 and 5.6). The frequency of DNA rearrangement in expression cassettes is lower in transgenic rice plants obtained by the Agrobacterium _ mediated method than those obtained by the biolistic method. The average rearrangement frequency is 0.07 to 0.106 for the Agrobacterium _mediated method, and 0.57 to 0.66 for the biolistic method. Our results suggest that it is better to compare the number of intact expression cassettes instead of the total copy number of the transgene in demonstrating their influence on the level of transgene expression. This is the first report on the frequency of expression cassette rearrangement in transgenic plants transformed with the same plasmid by two different transformation methods.展开更多
In order to achieve higher density of P/M steels using the die wall lubrication compacting method or powder lubricant in warm compaction process, the influence of different process parameters on the green density of w...In order to achieve higher density of P/M steels using the die wall lubrication compacting method or powder lubricant in warm compaction process, the influence of different process parameters on the green density of warm compacted samples was studied. According to the orthogonal test method, the authors systematically study the influence of the different compaction pressure, condition of lubrication and compaction temperature on the green density of the sample in the warm compaction process, and put forward the optimal process parameter of warm compaction experiment. It is found that, a high compaction pressure (≥700 MPa), die wall lubrication combined with a small amount of internal lubricants, and fitting compaction temperature by different condition of lubrication, are the optimal parameters in warm compaction process.展开更多
Allenes,served as highly sought-after building blocks,are an indispensable component of synthetic chemistry.Their utility in modulating the chemical,physical,and pharmaceutical properties of organic compounds make all...Allenes,served as highly sought-after building blocks,are an indispensable component of synthetic chemistry.Their utility in modulating the chemical,physical,and pharmaceutical properties of organic compounds make allenes a desirable choice in various applications.Here,we report a facile method for the atom-economical synthesis of propargyl allenylamines via an underdeveloped[2,3]-sigmatropic rearrangement.Our strategy employs easily accessible propargylamines as starting materials,which are first converted into propargyl ammonium salts,followed by a base-promoted[2,3]-sigmatropic rearrangement.This one-pot,two-step reaction proceeds in the absence of transition metals,displays a very broad scope,and does not require the introduction of the electron-withdrawing group into the starting materials.展开更多
For conformal Hardy-Littlewood-Sobolev(HLS)inequalities[22]and reversed conformal HLS inequalities[8]on S^(n),a new proof is given for the attainability of their sharp constants.Classical methods used in[22]and[8]depe...For conformal Hardy-Littlewood-Sobolev(HLS)inequalities[22]and reversed conformal HLS inequalities[8]on S^(n),a new proof is given for the attainability of their sharp constants.Classical methods used in[22]and[8]depends on rearrangement inequalities.Here,we use the subcritical approach to construct the extremal sequence and circumvent the blow-up phenomenon by renormalization method.The merit of the method is that it does not rely on rearrangement inequalities.展开更多
文摘Transferring foreign DNA into plant cells by biolistic and Agrobacterium _mediated methods may result in random integration of different copy numbers of the transgene, and different proportions of intact vs. rearranged copies of the transgene. This may, in turn, affect transgene expression levels. To test the above hypothesis, we first introduced the same plasmid, pAc1PG_CAM, into rice (Oryza sativa L.) calli separately by the biolistic method and by the Agrobacterium _mediated method. To show whether different plasmids may affect the results, we also introduced pTOK233 by the Agrobacterium _mediated method and pJPM44 by the biolistic method. Transgene expression of R0 plants was monitored by histochemical analysis of GUS activity. Transgene copy number was determined by Southern blot analysis after digesting genomic DNA with an enzyme that has a unique cutting site within the input plasmid. The total genomic DNA was also digested by a two_cut enzyme (the cuts are located at two sides of a given transgene expression cassette), followed by Southern blotting analysis, for determining the number of intact transgene expression cassettes. Our data showed that Agrobacterium _mediated transformation resulted in lower transgene copy number (average between 2.1 and 2.3) in transgenic rice plants, compared with those plants obtained by the biolistic method (average between 4.2 and 5.6). The frequency of DNA rearrangement in expression cassettes is lower in transgenic rice plants obtained by the Agrobacterium _ mediated method than those obtained by the biolistic method. The average rearrangement frequency is 0.07 to 0.106 for the Agrobacterium _mediated method, and 0.57 to 0.66 for the biolistic method. Our results suggest that it is better to compare the number of intact expression cassettes instead of the total copy number of the transgene in demonstrating their influence on the level of transgene expression. This is the first report on the frequency of expression cassette rearrangement in transgenic plants transformed with the same plasmid by two different transformation methods.
基金the National Scientific and Technological Project(No.MKPT-2004-09ZD)the Innovative Engineering Program of Central South University
文摘In order to achieve higher density of P/M steels using the die wall lubrication compacting method or powder lubricant in warm compaction process, the influence of different process parameters on the green density of warm compacted samples was studied. According to the orthogonal test method, the authors systematically study the influence of the different compaction pressure, condition of lubrication and compaction temperature on the green density of the sample in the warm compaction process, and put forward the optimal process parameter of warm compaction experiment. It is found that, a high compaction pressure (≥700 MPa), die wall lubrication combined with a small amount of internal lubricants, and fitting compaction temperature by different condition of lubrication, are the optimal parameters in warm compaction process.
基金the National Natural Science Foundation of China(No.22078192)National Key Research and Development Program of China(Nos.2023YFC2412400,2023YFC2412403)forfinancial support.
文摘Allenes,served as highly sought-after building blocks,are an indispensable component of synthetic chemistry.Their utility in modulating the chemical,physical,and pharmaceutical properties of organic compounds make allenes a desirable choice in various applications.Here,we report a facile method for the atom-economical synthesis of propargyl allenylamines via an underdeveloped[2,3]-sigmatropic rearrangement.Our strategy employs easily accessible propargylamines as starting materials,which are first converted into propargyl ammonium salts,followed by a base-promoted[2,3]-sigmatropic rearrangement.This one-pot,two-step reaction proceeds in the absence of transition metals,displays a very broad scope,and does not require the introduction of the electron-withdrawing group into the starting materials.
基金supported by the National Natural Science Foundation of China(Grant No.12071269)Natural Science Foundation of Zhejiang Province(Grant No.LY18A010013).
文摘For conformal Hardy-Littlewood-Sobolev(HLS)inequalities[22]and reversed conformal HLS inequalities[8]on S^(n),a new proof is given for the attainability of their sharp constants.Classical methods used in[22]and[8]depends on rearrangement inequalities.Here,we use the subcritical approach to construct the extremal sequence and circumvent the blow-up phenomenon by renormalization method.The merit of the method is that it does not rely on rearrangement inequalities.