作者研究了破伤风毒素及其 AB 片段对金鱼和小鼠的毒力,发现16ng 的毒素即可使金鱼麻痹和死亡;26μg 的 AB 片段即可使小鼠麻痹和死亡,而对金鱼却无作用。当抗 C 或 AB 片段的抗体与毒素结合后,可阻断毒素对金鱼的致麻痹作用。上述结果...作者研究了破伤风毒素及其 AB 片段对金鱼和小鼠的毒力,发现16ng 的毒素即可使金鱼麻痹和死亡;26μg 的 AB 片段即可使小鼠麻痹和死亡,而对金鱼却无作用。当抗 C 或 AB 片段的抗体与毒素结合后,可阻断毒素对金鱼的致麻痹作用。上述结果表明,破伤风毒素可作用于金鱼的外周神经系统,而 AB 片段则不能。毒素与其受体结合是毒素对金鱼作用所必需的。展开更多
To characterize the DNA rearrangement of both the T-DNA region and the genomic insertion site during T-DNA insertion, the Genomewalker strategy was used to isolate the junctions between the inserted DNA and the plant ...To characterize the DNA rearrangement of both the T-DNA region and the genomic insertion site during T-DNA insertion, the Genomewalker strategy was used to isolate the junctions between the inserted DNA and the plant genomic DNA in six rapeseed events as well as the genomic DNA at the sites before integration. During transformation in each of the six events, portions of both the right border（RB） and left border（LB） regions of the T-DNA were deleted, ranging from a 7 nucleotide deletion of the LB repeats in event RF1 to a 207 bp deletion of the LB region in event RF2. For the six events, T-DNA integration resulted in a deletion at the target site spanning less than 100 bp. Sequence analysis indicated that the T-DNA was integrated into the coding region of various native rapeseed genes in events RF1 and RF2. Duplications of the genomic DNA target site were observed in events RF2, RF3 and Topas 19/2. And multimerization of transgenes was found in event Topas 19/2, in which, the T-DNA was integrated as a head-to-head（RB-to-RB） concatemer into the recipient genome. In event MS1, chromosomal translocation or a large target-site deletion may have occurred during T-DNA integration, which was identified due to a failure to amplify the presumptive insertion site based on the flanking rapeseed DNA sequences. Our results provide comprehensive data concerning transgene organization and the genomic context of the T-DNA in six rapeseed events, which can aid in the developing of insert fingerprinting and the monitoring of long-term genetic stability and potential unintended effects of transgenic events.展开更多
Objective To study the human dystrophin gene molecular deletion mechanism, we analyzed breakpoint regions within junction fragments of deletion-type patients and investigated whether the dystrophin gene's intron s...Objective To study the human dystrophin gene molecular deletion mechanism, we analyzed breakpoint regions within junction fragments of deletion-type patients and investigated whether the dystrophin gene's intron structure might be related to intron instability.Methods Junction fragments corresponding to exon 46 and 51 deletions were cloned. The breakpoint regions were sequenced, and the features of introns with available Genebank sequences were analyzed.Results An analysis of junction fragment sequences corresponding to exon 46 and 51 deletions showed that all 5' and 3' breakpoints are located within repeat sequences. No small insertions, small deletions, or point mutations are located near the breakpoint junctions. By analyzing the secondary structure of the junction fragments, we demonstrated that all junction fragment breakpoints are located in non-matching regions of single-stranded hairpin loops. A high concentration of repetitive elements is found to be a key feature of many dystrophin introns. In total, 34. 8% of the overall dystrophin intron sequences is composed of repeat sequences.Conclusion Repeat elements in many dystrophin gene introns are the key to their structural bases and reflect intron instability. As a result of the primary DNA sequences, single-stranded hairpin loops form, increasing the instability of the gene, and forming the base for breaks in the DNA. The formation of the single-stranded hairpins can result in reattachment of two different breakpoints, producing a deletion.展开更多
文摘作者研究了破伤风毒素及其 AB 片段对金鱼和小鼠的毒力,发现16ng 的毒素即可使金鱼麻痹和死亡;26μg 的 AB 片段即可使小鼠麻痹和死亡,而对金鱼却无作用。当抗 C 或 AB 片段的抗体与毒素结合后,可阻断毒素对金鱼的致麻痹作用。上述结果表明,破伤风毒素可作用于金鱼的外周神经系统,而 AB 片段则不能。毒素与其受体结合是毒素对金鱼作用所必需的。
基金supported by the grant from the National Major Special Project for the Development of Transgenic Organisms,China(2013ZX08012-003 and 2011ZX08012-005)the Special Funds of the State Environmental Protection Public Welfare Industry,China(201109028)
文摘To characterize the DNA rearrangement of both the T-DNA region and the genomic insertion site during T-DNA insertion, the Genomewalker strategy was used to isolate the junctions between the inserted DNA and the plant genomic DNA in six rapeseed events as well as the genomic DNA at the sites before integration. During transformation in each of the six events, portions of both the right border（RB） and left border（LB） regions of the T-DNA were deleted, ranging from a 7 nucleotide deletion of the LB repeats in event RF1 to a 207 bp deletion of the LB region in event RF2. For the six events, T-DNA integration resulted in a deletion at the target site spanning less than 100 bp. Sequence analysis indicated that the T-DNA was integrated into the coding region of various native rapeseed genes in events RF1 and RF2. Duplications of the genomic DNA target site were observed in events RF2, RF3 and Topas 19/2. And multimerization of transgenes was found in event Topas 19/2, in which, the T-DNA was integrated as a head-to-head（RB-to-RB） concatemer into the recipient genome. In event MS1, chromosomal translocation or a large target-site deletion may have occurred during T-DNA integration, which was identified due to a failure to amplify the presumptive insertion site based on the flanking rapeseed DNA sequences. Our results provide comprehensive data concerning transgene organization and the genomic context of the T-DNA in six rapeseed events, which can aid in the developing of insert fingerprinting and the monitoring of long-term genetic stability and potential unintended effects of transgenic events.
基金the National Natural Science Foundation of China ( Nos. 39700048 and 30271378) the Guangdong Natural Science Foundation (Nos. 980066, 021866 and 974151)+1 种基金and as a key project of the Guangdong Provincial Committee on Science Technology (No. 2002C306
文摘Objective To study the human dystrophin gene molecular deletion mechanism, we analyzed breakpoint regions within junction fragments of deletion-type patients and investigated whether the dystrophin gene's intron structure might be related to intron instability.Methods Junction fragments corresponding to exon 46 and 51 deletions were cloned. The breakpoint regions were sequenced, and the features of introns with available Genebank sequences were analyzed.Results An analysis of junction fragment sequences corresponding to exon 46 and 51 deletions showed that all 5' and 3' breakpoints are located within repeat sequences. No small insertions, small deletions, or point mutations are located near the breakpoint junctions. By analyzing the secondary structure of the junction fragments, we demonstrated that all junction fragment breakpoints are located in non-matching regions of single-stranded hairpin loops. A high concentration of repetitive elements is found to be a key feature of many dystrophin introns. In total, 34. 8% of the overall dystrophin intron sequences is composed of repeat sequences.Conclusion Repeat elements in many dystrophin gene introns are the key to their structural bases and reflect intron instability. As a result of the primary DNA sequences, single-stranded hairpin loops form, increasing the instability of the gene, and forming the base for breaks in the DNA. The formation of the single-stranded hairpins can result in reattachment of two different breakpoints, producing a deletion.
