Diaza Crown ethers are versatile complexing reagents, their complexing abilities are dramatically modified by the electron donating atoms on substituents attached to the nitrogen if they can give a three-dimensional c...Diaza Crown ethers are versatile complexing reagents, their complexing abilities are dramatically modified by the electron donating atoms on substituents attached to the nitrogen if they can give a three-dimensional cavity as in cryptates. Hence the synthesis and characterization of bibracchial lariat ethers (BIBLES) have received much attention. In the preparation of new BIBLES, a complex Ⅱ was unexpectedly obtained.展开更多
Bis diphenyl 22 and 11 Membered Ring N pivot lariat Crown Ethers were prepared by one step reaction of 2,2' dihydroxy diphenyl with N tosyl diethanolamine ditoskylate in DMF at refluxing tem perature unde...Bis diphenyl 22 and 11 Membered Ring N pivot lariat Crown Ethers were prepared by one step reaction of 2,2' dihydroxy diphenyl with N tosyl diethanolamine ditoskylate in DMF at refluxing tem perature under N z,Using anhydrous potassium carbonate as condensing agent,respectirely.The tosyl group of(1,2) were removed by treatment with 40%HBr in AcoH in the presence gf a large amount of phenol to give correspondence crown ether compounds(3,4).New N pirot lariat crown thers(5,6)were prepared by one step reaction of(3)with RBr(R=-CH 2CH=CH 2,-CH 2(CH 2) 14 CH 3) in CH 3CN at refluxing temperature under N 2,Using anhydrous K 2CO 3 as condensing agent.New N pivot lariat croon ether(7) were prepared by one step reaction (4)with n bromohexadecane in CH 3CN at refluxing temperature under N 2, Using anhydrous potassium carbonate as condensing agent.New compounds(1,3,5,6,7)were characterized by IR,, 1H NMR,Ms and elemental analysis.展开更多
Lariat RNA is concomitantly produced by excised intron during RNA splicing,which is usually debranched by DBR1,an RNA debranching enzyme.However,increasing evidence showed that some lariat RNA could escape debranching...Lariat RNA is concomitantly produced by excised intron during RNA splicing,which is usually debranched by DBR1,an RNA debranching enzyme.However,increasing evidence showed that some lariat RNA could escape debranching.Little is known about how and why these lariat RNAs could be retained.By comparing the atlas of lariat RNAs between the non-dividing cell(mature pollen)and three actively dividing tissues(young shoot apex,young seeds,and young roots),we identified hundreds to thousands of lariat RNA naturally retained in each tissue,and the incidence of lariat RNA retention is much less in shoot apex while much more in pollen.Many lariat RNAs derived from the same intron or different lariat RNAs from the same pre-m RNA could be retained in one tissue while degraded in the other tissues.By deciphering lariat RNA sequences,we identified an AG-rich(RAAAAVAAAR)motif and a UC-rich(UCUCUYUCUC)motif for pollen-specific and the other three tissues-retained lariat RNAs,respectively.Reconstitution of the pollen-specific AG-rich motif indeed enhanced lariat RNA retention in plants.Biologically,hundreds of lariat RNAs harbored mi RNA binding sites,and dual-luciferase reporter assay showed that these natural lariat RNAs had the potential to protect expression of mi RNA target genes.Collectively,our results uncover that selective retention of lariat RNA is an actively regulatory process,and provide new insights into understanding how lariat RNA metabolism may impact mi RNA activity.展开更多
Lariat RNA is produced during pre-mRNA splicing, and it is traditionally thought as by-products, due to the quick turnover by debranching followed by degradation. However, recent findings identified many lariat RNAs a...Lariat RNA is produced during pre-mRNA splicing, and it is traditionally thought as by-products, due to the quick turnover by debranching followed by degradation. However, recent findings identified many lariat RNAs accumulate with a circular form in higher eukaryotes. Although the remarkable accumulation, biological consequence of lariat-derived circular RNAs(here we name laciRNAs) remains largely unknown. Here, we report that a specific laciRNA from At5 g37720 plays an essential role in plant development by regulating gene expression globally. We focus on 17 laciRNAs with accumulation in wild type plants by circular RNA sequencing in Arabidopsis. To determine biological functions of these laciRNAs, we constructed one pair of transgenic plants for each laciRNA, in which the local gene with or without introns was over-expressed in wild type plants,respectively. By comparing morphological phenotypes and transcriptomic profiles between two classes of transgenic plants, we show that over-expression of the laciRNA derived from the 1 st intron of At5 g37720 causes pleiotropic phenotypes, including curly and clustered leaf, late flowering, reduced fertility, and accompanied with altered expression of approximately 800 genes.Our results provide another example that a specific plant circular RNA regulates gene expression in a similar manner to that of other non-coding RNAs under physiological conditions.展开更多
Background： Most intronic lariats are rapidly turned over after splicing. However, new research suggests that some introns may have additional post-splicing functions. Current bioinformatics methods used to identify ...Background： Most intronic lariats are rapidly turned over after splicing. However, new research suggests that some introns may have additional post-splicing functions. Current bioinformatics methods used to identify lariats require a sequencing read that traverses the lariat branchpoint. This method provides precise branchpoint sequence and position information, but is limited in its ability to quantify abundance of stabilized lariat species in a given RNAseq sample. Bioinformatic tools are needed to better address these emerging biological questions. Methods： We used an unsupervised machine learning approach on sequencing reads from publicly available ENCODE data to learn to identify and quantify lariats based on RNAseq read coverage shape. Results： We developed ShapeShifter, a novel approach for identifying and quantifying stable lariat species in RNAseq datasets. We learned a characteristic ＂lariat＂ curve from ENCODE RNAseq data and were able to estimate abundances for introns based on read coverage. Using this method we discovered new stable introns in these samples that were not represented using the older, branchpoint-traversing read method. Conclusions： ShapeShifter provides a robust approach towards detecting and quantifying stable lariat species.展开更多
基金Supported by the National Natural Science foundation of China Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics, Academic Soinica, Wuhan
文摘Diaza Crown ethers are versatile complexing reagents, their complexing abilities are dramatically modified by the electron donating atoms on substituents attached to the nitrogen if they can give a three-dimensional cavity as in cryptates. Hence the synthesis and characterization of bibracchial lariat ethers (BIBLES) have received much attention. In the preparation of new BIBLES, a complex Ⅱ was unexpectedly obtained.
文摘Bis diphenyl 22 and 11 Membered Ring N pivot lariat Crown Ethers were prepared by one step reaction of 2,2' dihydroxy diphenyl with N tosyl diethanolamine ditoskylate in DMF at refluxing tem perature under N z,Using anhydrous potassium carbonate as condensing agent,respectirely.The tosyl group of(1,2) were removed by treatment with 40%HBr in AcoH in the presence gf a large amount of phenol to give correspondence crown ether compounds(3,4).New N pirot lariat crown thers(5,6)were prepared by one step reaction of(3)with RBr(R=-CH 2CH=CH 2,-CH 2(CH 2) 14 CH 3) in CH 3CN at refluxing temperature under N 2,Using anhydrous K 2CO 3 as condensing agent.New N pivot lariat croon ether(7) were prepared by one step reaction (4)with n bromohexadecane in CH 3CN at refluxing temperature under N 2, Using anhydrous potassium carbonate as condensing agent.New compounds(1,3,5,6,7)were characterized by IR,, 1H NMR,Ms and elemental analysis.
基金supported by the National Natural Science Foundation of China(31830045,32025005,32100429)。
文摘Lariat RNA is concomitantly produced by excised intron during RNA splicing,which is usually debranched by DBR1,an RNA debranching enzyme.However,increasing evidence showed that some lariat RNA could escape debranching.Little is known about how and why these lariat RNAs could be retained.By comparing the atlas of lariat RNAs between the non-dividing cell(mature pollen)and three actively dividing tissues(young shoot apex,young seeds,and young roots),we identified hundreds to thousands of lariat RNA naturally retained in each tissue,and the incidence of lariat RNA retention is much less in shoot apex while much more in pollen.Many lariat RNAs derived from the same intron or different lariat RNAs from the same pre-m RNA could be retained in one tissue while degraded in the other tissues.By deciphering lariat RNA sequences,we identified an AG-rich(RAAAAVAAAR)motif and a UC-rich(UCUCUYUCUC)motif for pollen-specific and the other three tissues-retained lariat RNAs,respectively.Reconstitution of the pollen-specific AG-rich motif indeed enhanced lariat RNA retention in plants.Biologically,hundreds of lariat RNAs harbored mi RNA binding sites,and dual-luciferase reporter assay showed that these natural lariat RNAs had the potential to protect expression of mi RNA target genes.Collectively,our results uncover that selective retention of lariat RNA is an actively regulatory process,and provide new insights into understanding how lariat RNA metabolism may impact mi RNA activity.
基金supported by the National Natural Science Foundation of China (31422029, 31470281, 31671261)the Recruitment Program of Global Experts (China)
文摘Lariat RNA is produced during pre-mRNA splicing, and it is traditionally thought as by-products, due to the quick turnover by debranching followed by degradation. However, recent findings identified many lariat RNAs accumulate with a circular form in higher eukaryotes. Although the remarkable accumulation, biological consequence of lariat-derived circular RNAs(here we name laciRNAs) remains largely unknown. Here, we report that a specific laciRNA from At5 g37720 plays an essential role in plant development by regulating gene expression globally. We focus on 17 laciRNAs with accumulation in wild type plants by circular RNA sequencing in Arabidopsis. To determine biological functions of these laciRNAs, we constructed one pair of transgenic plants for each laciRNA, in which the local gene with or without introns was over-expressed in wild type plants,respectively. By comparing morphological phenotypes and transcriptomic profiles between two classes of transgenic plants, we show that over-expression of the laciRNA derived from the 1 st intron of At5 g37720 causes pleiotropic phenotypes, including curly and clustered leaf, late flowering, reduced fertility, and accompanied with altered expression of approximately 800 genes.Our results provide another example that a specific plant circular RNA regulates gene expression in a similar manner to that of other non-coding RNAs under physiological conditions.
文摘Background： Most intronic lariats are rapidly turned over after splicing. However, new research suggests that some introns may have additional post-splicing functions. Current bioinformatics methods used to identify lariats require a sequencing read that traverses the lariat branchpoint. This method provides precise branchpoint sequence and position information, but is limited in its ability to quantify abundance of stabilized lariat species in a given RNAseq sample. Bioinformatic tools are needed to better address these emerging biological questions. Methods： We used an unsupervised machine learning approach on sequencing reads from publicly available ENCODE data to learn to identify and quantify lariats based on RNAseq read coverage shape. Results： We developed ShapeShifter, a novel approach for identifying and quantifying stable lariat species in RNAseq datasets. We learned a characteristic ＂lariat＂ curve from ENCODE RNAseq data and were able to estimate abundances for introns based on read coverage. Using this method we discovered new stable introns in these samples that were not represented using the older, branchpoint-traversing read method. Conclusions： ShapeShifter provides a robust approach towards detecting and quantifying stable lariat species.
