More than 160 types of post-transcriptional RNA modifications have been reported;there is substantial variation in modification type,abundance,site,and function across species,tissues,and RNA type.The recent developme...More than 160 types of post-transcriptional RNA modifications have been reported;there is substantial variation in modification type,abundance,site,and function across species,tissues,and RNA type.The recent development of high-throughput detection technology has enabled identification of diverse dynamic and reversible RNA modifications,including N6,2′-O-dimethyladenosine(m6Am),N1-methyladenosine(m1A),5-methylcytosine(m5C),N6-methyladenosine(m6A),pseudouridine(Ψ),and inosine(I).In this review,we focus on eukaryotic mRNA modifications.We summarize their biogenesis,regulatory mechanisms,and biological functions,as well as highthroughput methods for detection of mRNA modifications.We also discuss challenges that must be addressed in mRNA modification research.展开更多
The hot workability and dynamic recrystallization(DRX)mechanisms of pure nickel N6 were systematically investigated using hot compression tests.Based on hot compression data,the constitutive equation of N6 was develop...The hot workability and dynamic recrystallization(DRX)mechanisms of pure nickel N6 were systematically investigated using hot compression tests.Based on hot compression data,the constitutive equation of N6 was developed and its reliability was verified.Its hot processing map was constructed,and combined with microstructural observations,a semi-quantitative response relationship between hot deformation parameters and microstructure was established.The DRX process of N6 is a thermally activated process and particularly sensitive to the strain rate.The optimal hot processing parameters for N6 were determined to be 950−1050℃ and 0.1−1 s^(−1).Furthermore,it was proven that the dominant nucleation mechanism is discontinuous DRX characterized by grain boundary bulging and twins assisting nucleation,while the continuous DRX characterized by subgrains combined with rotation is an inactive nucleation mechanism.展开更多
Two silver(I) complexes were obtained by the reaction of a N6 ligand with [Ag(PPh3)2(MeCN)](SbF6). In complex [AgL1(PPh3)](SbF6) 1, the silver center is bound to three N donors of the nitrogen ligand and P donor of ...Two silver(I) complexes were obtained by the reaction of a N6 ligand with [Ag(PPh3)2(MeCN)](SbF6). In complex [AgL1(PPh3)](SbF6) 1, the silver center is bound to three N donors of the nitrogen ligand and P donor of one triphenylphosphine group, forming an irregular AgN3P tetrahedron. In complex [Ag(PPh3)4](SbF6) 2, the Ag+ ion is coordinated to four triphenyl- phosphine groups, affording a tetrahedral geometry. Crystal data for complex 1: C30H37AgF6N6PSb, Mr = 856.25, orthorhombic, space group Pbca, a = 19.0702(9), b = 15.9047(7), c = 21.498(1) ?, V = 6520.5(6) ?3, Z = 8, Dc= 1.744 g/cm3, F(000) = 3408, μ = 1.544 mm-1, the final R = 0.0367 and wR = 0.1077 for 5325 observed reflections with I > 2σ(I); and those for 2: C72H60AgF6P4Sb, Mr = 1392.70, trigonal, space group R3, a = 14.4577(6), b = 14.4577(6), c = 51.544(2) ?, V = 9330.5(7) ?3, Z = 6, Dc= 1.487 g/cm3, F(000) = 4224, μ = 0.913 mm-1, the final R = 0.0352 and wR = 0.1089 for 3498 observed reflections with I > 2σ(I).展开更多
N6-methyl-adenosine （m6A） is one of the most common and abundant modifications on RNA molecules present in eukaryotes. However, the biological significance of m6A methylation remains largely unknown. Several indepen...N6-methyl-adenosine （m6A） is one of the most common and abundant modifications on RNA molecules present in eukaryotes. However, the biological significance of m6A methylation remains largely unknown. Several independent lines of evidence suggest that the dynamic regulation ofm6A may have a profound impact on gene expression regulation. The m6A modification is catalyzed by an unidentified methyltransferase complex containing at least one subunit methyltransferase like 3 （METTL3）. m6A modification on messenger RNAs （mRNAs） mainly occurs in the exonic regions and 3＇-untranslated region （3＇-UTR） as revealed by high-throughput m6A-seq. One significant advance in m6A research is the recent discovery of the first two m6A RNA demethylases fat mass and obesity- associated （FTO） gene and ALKBH5, which catalyze m6A demethylation in an cx-ketoglutarate （a-KG）- and FeZ ＋ -dependent manner. Recent studies in model organisms demonstrate that METTL3, FTO and ALKBH5 play important roles in many biological processes, ranging from devel- opment and metabolism to fertility. Moreover, perturbation of activities of these enzymes leads to the disturbed expression of thousands of genes at the cellular level, implicating a regulatory role ofm6A in RNA metabolism. Given the vital roles of DNA and histone methylations in epigenetic regulation of basic life processes in mammals, the dynamic and reversible chemical m6A modification on RNA may also serve as a novel epigenetic marker of profound biological significances.展开更多
基金the Ministry of Science and Technology of China(2019YFA0110902,2019YFA0802201)。
文摘More than 160 types of post-transcriptional RNA modifications have been reported;there is substantial variation in modification type,abundance,site,and function across species,tissues,and RNA type.The recent development of high-throughput detection technology has enabled identification of diverse dynamic and reversible RNA modifications,including N6,2′-O-dimethyladenosine(m6Am),N1-methyladenosine(m1A),5-methylcytosine(m5C),N6-methyladenosine(m6A),pseudouridine(Ψ),and inosine(I).In this review,we focus on eukaryotic mRNA modifications.We summarize their biogenesis,regulatory mechanisms,and biological functions,as well as highthroughput methods for detection of mRNA modifications.We also discuss challenges that must be addressed in mRNA modification research.
基金supported by the Science Foundation for Distinguished Young Scholars of Gansu Province,China(No.18JR3RA134)Lanzhou University of Technology Support Plan for Excellent Young Scholars,China(No.CGZH001)the National Nature Science Foundation of China(No.51665032).
文摘The hot workability and dynamic recrystallization(DRX)mechanisms of pure nickel N6 were systematically investigated using hot compression tests.Based on hot compression data,the constitutive equation of N6 was developed and its reliability was verified.Its hot processing map was constructed,and combined with microstructural observations,a semi-quantitative response relationship between hot deformation parameters and microstructure was established.The DRX process of N6 is a thermally activated process and particularly sensitive to the strain rate.The optimal hot processing parameters for N6 were determined to be 950−1050℃ and 0.1−1 s^(−1).Furthermore,it was proven that the dominant nucleation mechanism is discontinuous DRX characterized by grain boundary bulging and twins assisting nucleation,while the continuous DRX characterized by subgrains combined with rotation is an inactive nucleation mechanism.
基金This work was supported by the NSF of Fujian Province (E0310029)and the Innovation Fund of Fujian Province (2003J044)
文摘Two silver(I) complexes were obtained by the reaction of a N6 ligand with [Ag(PPh3)2(MeCN)](SbF6). In complex [AgL1(PPh3)](SbF6) 1, the silver center is bound to three N donors of the nitrogen ligand and P donor of one triphenylphosphine group, forming an irregular AgN3P tetrahedron. In complex [Ag(PPh3)4](SbF6) 2, the Ag+ ion is coordinated to four triphenyl- phosphine groups, affording a tetrahedral geometry. Crystal data for complex 1: C30H37AgF6N6PSb, Mr = 856.25, orthorhombic, space group Pbca, a = 19.0702(9), b = 15.9047(7), c = 21.498(1) ?, V = 6520.5(6) ?3, Z = 8, Dc= 1.744 g/cm3, F(000) = 3408, μ = 1.544 mm-1, the final R = 0.0367 and wR = 0.1077 for 5325 observed reflections with I > 2σ(I); and those for 2: C72H60AgF6P4Sb, Mr = 1392.70, trigonal, space group R3, a = 14.4577(6), b = 14.4577(6), c = 51.544(2) ?, V = 9330.5(7) ?3, Z = 6, Dc= 1.487 g/cm3, F(000) = 4224, μ = 0.913 mm-1, the final R = 0.0352 and wR = 0.1089 for 3498 observed reflections with I > 2σ(I).
基金supported by the China 973 programs (Grant No.2011CB510103 and 2012CB518302) awarded to YGYthe CAS Innovation Program for Young Scientists to YN+1 种基金the CAS "100-talents" Professor Program to YGYthe National Natural Science Foundation of China (Grant No. 30900724 and 81071648) to YN
文摘N6-methyl-adenosine （m6A） is one of the most common and abundant modifications on RNA molecules present in eukaryotes. However, the biological significance of m6A methylation remains largely unknown. Several independent lines of evidence suggest that the dynamic regulation ofm6A may have a profound impact on gene expression regulation. The m6A modification is catalyzed by an unidentified methyltransferase complex containing at least one subunit methyltransferase like 3 （METTL3）. m6A modification on messenger RNAs （mRNAs） mainly occurs in the exonic regions and 3＇-untranslated region （3＇-UTR） as revealed by high-throughput m6A-seq. One significant advance in m6A research is the recent discovery of the first two m6A RNA demethylases fat mass and obesity- associated （FTO） gene and ALKBH5, which catalyze m6A demethylation in an cx-ketoglutarate （a-KG）- and FeZ ＋ -dependent manner. Recent studies in model organisms demonstrate that METTL3, FTO and ALKBH5 play important roles in many biological processes, ranging from devel- opment and metabolism to fertility. Moreover, perturbation of activities of these enzymes leads to the disturbed expression of thousands of genes at the cellular level, implicating a regulatory role ofm6A in RNA metabolism. Given the vital roles of DNA and histone methylations in epigenetic regulation of basic life processes in mammals, the dynamic and reversible chemical m6A modification on RNA may also serve as a novel epigenetic marker of profound biological significances.
