The timing of floral transition is critical to reproductive success in angiosperms and is genetically controlled by a network of flowering genes. In Arabidopsis, expression of certain flowering genes is regulated by v...The timing of floral transition is critical to reproductive success in angiosperms and is genetically controlled by a network of flowering genes. In Arabidopsis, expression of certain flowering genes is regulated by various chromatin modifications, among which are two central regulators of flowering, namely FLOWERING LOCUS C （FLC） and FLOWERING LOCUS T（FT）. Recent studies have revealed that a number of chromatin-modifying components are involved in activation or repression of FLC expression. Activation of FLC expression is associated with various ＇active＇ chromatln modifications including acetylation of core histone tails, histone H3 lysine-4 （H3K4） methylation, H2B monoubiquitination, H3 lysine-36 （H3K36） di- and tri-methylation and deposition of the histone variant H2A.Z, whereas various ＇repressive＇ histone mod- ifications are associated with FLC repression, including histone deacetylation, H3K4 demethylation, histone H3 lysine-9 （H3K9） and H3 lysine-27 （H3K27） methylation, and histone arginine methylation. In addition, recent studies have revealed that Polycomb group gene-mediated transcriptional-silencing mechanism not only represses FLC expression, but also directly represses FTexpression. Regulation of FLC expression provides a paradigm for control of the expression of other developmental genes in plants through chromatin mechanisms.展开更多
以对甲基苯甲醛(4-methyl benzaldehyde,简称4-MB)为改性剂,在对甲苯磺酸(PTS)的作用下对煤沥青(coal tar pitch)进行了改性。采用偏光显微镜研究了4-MB改性煤沥青的光学组织;考察了4-MB用量,反应温度和反应时间对改性沥青的软化点、密...以对甲基苯甲醛(4-methyl benzaldehyde,简称4-MB)为改性剂,在对甲苯磺酸(PTS)的作用下对煤沥青(coal tar pitch)进行了改性。采用偏光显微镜研究了4-MB改性煤沥青的光学组织;考察了4-MB用量,反应温度和反应时间对改性沥青的软化点、密度、残炭率的影响。结果表明,在同一反应条件下,随4-MB用量的增加,改性沥青的密度、软化点、残炭率先显著提高后稍有降低。随着反应温度的提高及反应时间的延长,改性沥青的密度、软化点、残炭率先明显提高,后增加不大。可通过添加不同的4-MB用量或调节反应温度控制改性沥青的中间相小球的数量和球径的大小,从而改善得到较好的光学组织。展开更多
The dynamic RNA modifications have been viewed as new posttranscriptional regulator in modulating gene expression as well as in a broad range of physiological processes.N^(1)-methyladenosine(m^(1)A)is one of the most ...The dynamic RNA modifications have been viewed as new posttranscriptional regulator in modulating gene expression as well as in a broad range of physiological processes.N^(1)-methyladenosine(m^(1)A)is one of the most prevalent modifications existing in multiple types of RNAs.In-depth investigation of the functions of m^(1)A requires the site-specific assessment of m^(1)A stoichiometry in RNA.Herein,we established a demethylase-assisted method(DA-m^(1)A)for the site-specific detection and quantification of m^(1)A in RNA.N^(1)-methyl group in m^(1)A could result in the stalling of reverse transcription at m^(1)A site,thus producing the truncated cDNA.E.coli AlkB is a demethylase that can demethylate m^(1)A to produce adenine in RNA,thus generating full-length cDNA from AlkB-treated RNA.Evaluation of the produced amounts of full-length cDNA by quantitative real-time PCR can achieve the site-specific detection and quantification of m^(1)A in RNA.With the DA-m^(1)A method,we examined and successfully confirmed the previously well-characterized m^(1)A sites in various types of RNAs with low false positive rate.In addition,we found that the level of m^(1)A was significantly decreased at the bromodomain containing 2(BRD2)mRNA position 1674 and CST telomere replication complex component 1(CTC1)mRNA position 5643 in human hepatocellular carcinoma tissues.The results suggest that these two m^(1)A sites in mRNA may be involved in liver tumorigenesis.Taken together,the DA-m^(1)A method is simple and enables the rapid,cost-effective,and site-specific detection and quantification of m^(1)A in RNA,which provides a valuable tool to decipher the functions of m^(1)A in human diseases.展开更多
为提高单根竹纤维的力学性能,对纳米浸渍改性竹纤维进行了超声处理,并研究了超声时间和超声频率对单根改性竹纤维拉伸性能的影响。采用场发射环境扫描电镜(FEESEM)、高精度力学性能测试仪(HPMPT)和激光共聚焦扫描显微镜(CLSM)对超声处...为提高单根竹纤维的力学性能,对纳米浸渍改性竹纤维进行了超声处理,并研究了超声时间和超声频率对单根改性竹纤维拉伸性能的影响。采用场发射环境扫描电镜(FEESEM)、高精度力学性能测试仪(HPMPT)和激光共聚焦扫描显微镜(CLSM)对超声处理的单根改性竹纤维表面形貌、Ca CO3附着量以及力学性能进行了表征。结果表明,超声处理改性竹纤维的拉伸强度和弹性模量较未处理竹纤维分别提高了15.99%和7.81%,其最优工艺条件为超声频率45 k Hz,超声时间10 min。展开更多
文摘The timing of floral transition is critical to reproductive success in angiosperms and is genetically controlled by a network of flowering genes. In Arabidopsis, expression of certain flowering genes is regulated by various chromatin modifications, among which are two central regulators of flowering, namely FLOWERING LOCUS C （FLC） and FLOWERING LOCUS T（FT）. Recent studies have revealed that a number of chromatin-modifying components are involved in activation or repression of FLC expression. Activation of FLC expression is associated with various ＇active＇ chromatln modifications including acetylation of core histone tails, histone H3 lysine-4 （H3K4） methylation, H2B monoubiquitination, H3 lysine-36 （H3K36） di- and tri-methylation and deposition of the histone variant H2A.Z, whereas various ＇repressive＇ histone mod- ifications are associated with FLC repression, including histone deacetylation, H3K4 demethylation, histone H3 lysine-9 （H3K9） and H3 lysine-27 （H3K27） methylation, and histone arginine methylation. In addition, recent studies have revealed that Polycomb group gene-mediated transcriptional-silencing mechanism not only represses FLC expression, but also directly represses FTexpression. Regulation of FLC expression provides a paradigm for control of the expression of other developmental genes in plants through chromatin mechanisms.
文摘以对甲基苯甲醛(4-methyl benzaldehyde,简称4-MB)为改性剂,在对甲苯磺酸(PTS)的作用下对煤沥青(coal tar pitch)进行了改性。采用偏光显微镜研究了4-MB改性煤沥青的光学组织;考察了4-MB用量,反应温度和反应时间对改性沥青的软化点、密度、残炭率的影响。结果表明,在同一反应条件下,随4-MB用量的增加,改性沥青的密度、软化点、残炭率先显著提高后稍有降低。随着反应温度的提高及反应时间的延长,改性沥青的密度、软化点、残炭率先明显提高,后增加不大。可通过添加不同的4-MB用量或调节反应温度控制改性沥青的中间相小球的数量和球径的大小,从而改善得到较好的光学组织。
基金supported by the National Key R&D Program of China(Nos.2022YFC3400700 and 2022YFA0806600)the National Natural Science Foundation of China(Nos.22277093,22074110,21721005 and 22207090)+1 种基金the Interdisciplinary Innovative Talents Foundation from Renmin Hospital of Wuhan University(No.JCRCGW-2022-008)the Translational Medicine and Interdisciplinary Research Joint Fund of Zhongnan Hospital of Wuhan University(No.ZNJC202208)。
文摘The dynamic RNA modifications have been viewed as new posttranscriptional regulator in modulating gene expression as well as in a broad range of physiological processes.N^(1)-methyladenosine(m^(1)A)is one of the most prevalent modifications existing in multiple types of RNAs.In-depth investigation of the functions of m^(1)A requires the site-specific assessment of m^(1)A stoichiometry in RNA.Herein,we established a demethylase-assisted method(DA-m^(1)A)for the site-specific detection and quantification of m^(1)A in RNA.N^(1)-methyl group in m^(1)A could result in the stalling of reverse transcription at m^(1)A site,thus producing the truncated cDNA.E.coli AlkB is a demethylase that can demethylate m^(1)A to produce adenine in RNA,thus generating full-length cDNA from AlkB-treated RNA.Evaluation of the produced amounts of full-length cDNA by quantitative real-time PCR can achieve the site-specific detection and quantification of m^(1)A in RNA.With the DA-m^(1)A method,we examined and successfully confirmed the previously well-characterized m^(1)A sites in various types of RNAs with low false positive rate.In addition,we found that the level of m^(1)A was significantly decreased at the bromodomain containing 2(BRD2)mRNA position 1674 and CST telomere replication complex component 1(CTC1)mRNA position 5643 in human hepatocellular carcinoma tissues.The results suggest that these two m^(1)A sites in mRNA may be involved in liver tumorigenesis.Taken together,the DA-m^(1)A method is simple and enables the rapid,cost-effective,and site-specific detection and quantification of m^(1)A in RNA,which provides a valuable tool to decipher the functions of m^(1)A in human diseases.
文摘为提高单根竹纤维的力学性能,对纳米浸渍改性竹纤维进行了超声处理,并研究了超声时间和超声频率对单根改性竹纤维拉伸性能的影响。采用场发射环境扫描电镜(FEESEM)、高精度力学性能测试仪(HPMPT)和激光共聚焦扫描显微镜(CLSM)对超声处理的单根改性竹纤维表面形貌、Ca CO3附着量以及力学性能进行了表征。结果表明,超声处理改性竹纤维的拉伸强度和弹性模量较未处理竹纤维分别提高了15.99%和7.81%,其最优工艺条件为超声频率45 k Hz,超声时间10 min。
