Marker-free GFP transgenic tobacco plants were constructed based on Cre/lox site-specific recombination system. A GFP gene was introduced into the tobacco genome using the Bar gene as a linked selectable marker flanke...Marker-free GFP transgenic tobacco plants were constructed based on Cre/lox site-specific recombination system. A GFP gene was introduced into the tobacco genome using the Bar gene as a linked selectable marker flanked by recombination sites in a directed orientation. The Bar gene expression box was subsequently excised from the plant genome by a strategy of Cre gene retransformation. After removal of the Cre-NPT Ⅱ locus by genetic segregation through self-cross, plants that incorporated only the GFP transgene were obtained. Transgenic tobacco plants mediated by Agrobacterium tumefaciens were obtained, which resisted herbicide Basta and GFP expressed well, then the Cre gene was subsequently introduced into 5 plants of them, respectively, by retransformation. The leaf disks from Cre transgenic plants were used to test the resistance to Basta on the medium with 8 mg L-1 of PPT. The results showed that few discs were able to regenerate normally, and the excision at 76-100% efficiency depended on individual retransformation events. Evidence for a precise recombination event was confirmed by cloning the nucleotides sequence surrounding the lox sites of the Basta sensitive plants. The result indicated that the excision event in the recombination sites was precise and conservative, without loss or alteration of any submarginal nucleotides of the recombination sites. Bar gene excised plants were selfpollinated to allow segregation of the GFP gene from the Cre-NPT Ⅱ locus. The progenies from self-pollinated plants were scored for Kan senstivity, then the segregation of GFP gene from Cre-NPT Ⅱ locus in the Kan senstive plants were confirmed by PCR analysis subsequently. Hence, constructing marker-free transgenic tobacco plants by Cre/lox sitespecific recombination system was reliable, and the strategy presented here should be applicable to other plants for the construction of marker-free transgenic plants as well.展开更多
Understanding the nature of Pt active sites is of great importance for the structure-sensitive base-free oxidation of glycerol. In the present work, the remarkable Pt particle size effects on glycerol conversion and p...Understanding the nature of Pt active sites is of great importance for the structure-sensitive base-free oxidation of glycerol. In the present work, the remarkable Pt particle size effects on glycerol conversion and products formation from the oxidation of the primary and the secondary hydroxyl groups are understood by combining the model calculations and DFT calculations, aiming to discriminate the corresponding dominant Pt active sites. The Pt(100) facet is demonstrated to be the dominant active sites for the glycerol conversion and the products formation from the two routes. The insights revealed here could shed new light on fundamental understanding of the Pt particle size effects and then guiding the design and optimization of Pt-catalyzed base-free oxidation of glycerol toward targeted products.展开更多
Full thickness skin grafts and composite grafts are a workhorse in reconstructive surgery of nose and ear defects whether they are originated from trauma, cancer surgery or burns. The reliability of these grafts has b...Full thickness skin grafts and composite grafts are a workhorse in reconstructive surgery of nose and ear defects whether they are originated from trauma, cancer surgery or burns. The reliability of these grafts has been proved with an established clinical use and morbidity to the donor site is minimal if harvesting and donor site selection if appropriate. Use of double or multiple grafts to reconstruct a complex defect of the nose has not been described and our report is meaningful for the fact that it describes a further use of the surgical concept of grafting.展开更多
Exploration and characterization of grafting productions by experimental methods are often cumbersome or sometimes impossible.Therefore,quantum chemistry calculations were performed to characterize the graft sites of ...Exploration and characterization of grafting productions by experimental methods are often cumbersome or sometimes impossible.Therefore,quantum chemistry calculations were performed to characterize the graft sites of epoxy resin.According to the Gibbs free energy criterion of the second law of thermodynamic,the reported graft sites were confirmed,and more important,some unreported graft sites were found.In addition,method of increasing the number of graft sites was studied in this article.展开更多
基金the National Natural Science Foundation of China (30200185)the Science Foundation of Committee of Education of Chongqing Municipality,China (030208)
文摘Marker-free GFP transgenic tobacco plants were constructed based on Cre/lox site-specific recombination system. A GFP gene was introduced into the tobacco genome using the Bar gene as a linked selectable marker flanked by recombination sites in a directed orientation. The Bar gene expression box was subsequently excised from the plant genome by a strategy of Cre gene retransformation. After removal of the Cre-NPT Ⅱ locus by genetic segregation through self-cross, plants that incorporated only the GFP transgene were obtained. Transgenic tobacco plants mediated by Agrobacterium tumefaciens were obtained, which resisted herbicide Basta and GFP expressed well, then the Cre gene was subsequently introduced into 5 plants of them, respectively, by retransformation. The leaf disks from Cre transgenic plants were used to test the resistance to Basta on the medium with 8 mg L-1 of PPT. The results showed that few discs were able to regenerate normally, and the excision at 76-100% efficiency depended on individual retransformation events. Evidence for a precise recombination event was confirmed by cloning the nucleotides sequence surrounding the lox sites of the Basta sensitive plants. The result indicated that the excision event in the recombination sites was precise and conservative, without loss or alteration of any submarginal nucleotides of the recombination sites. Bar gene excised plants were selfpollinated to allow segregation of the GFP gene from the Cre-NPT Ⅱ locus. The progenies from self-pollinated plants were scored for Kan senstivity, then the segregation of GFP gene from Cre-NPT Ⅱ locus in the Kan senstive plants were confirmed by PCR analysis subsequently. Hence, constructing marker-free transgenic tobacco plants by Cre/lox sitespecific recombination system was reliable, and the strategy presented here should be applicable to other plants for the construction of marker-free transgenic plants as well.
基金financially supported by the Natural Science Foundation of China (21776077)the Shanghai Natural Science Foundation (17ZR1407300 and 17ZR1407500)+5 种基金the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learningthe Shanghai Rising-Star Program (17QA1401200)the Open Project of State Key Laboratory of Chemical Engineering (SKLChe-15C03)the State Key Laboratory of Organic– Inorganic Composites (oic-201801007)the Fundamental Research Funds for the Central Universities (222201718003)the 111 Project of the Ministry of Education of China (B08021)
文摘Understanding the nature of Pt active sites is of great importance for the structure-sensitive base-free oxidation of glycerol. In the present work, the remarkable Pt particle size effects on glycerol conversion and products formation from the oxidation of the primary and the secondary hydroxyl groups are understood by combining the model calculations and DFT calculations, aiming to discriminate the corresponding dominant Pt active sites. The Pt(100) facet is demonstrated to be the dominant active sites for the glycerol conversion and the products formation from the two routes. The insights revealed here could shed new light on fundamental understanding of the Pt particle size effects and then guiding the design and optimization of Pt-catalyzed base-free oxidation of glycerol toward targeted products.
文摘Full thickness skin grafts and composite grafts are a workhorse in reconstructive surgery of nose and ear defects whether they are originated from trauma, cancer surgery or burns. The reliability of these grafts has been proved with an established clinical use and morbidity to the donor site is minimal if harvesting and donor site selection if appropriate. Use of double or multiple grafts to reconstruct a complex defect of the nose has not been described and our report is meaningful for the fact that it describes a further use of the surgical concept of grafting.
基金supported by the Program of Introducing Talents of Discipline to Universities(No.B08003).
文摘Exploration and characterization of grafting productions by experimental methods are often cumbersome or sometimes impossible.Therefore,quantum chemistry calculations were performed to characterize the graft sites of epoxy resin.According to the Gibbs free energy criterion of the second law of thermodynamic,the reported graft sites were confirmed,and more important,some unreported graft sites were found.In addition,method of increasing the number of graft sites was studied in this article.
