Synonymous Codon Usage of Both Alternativelyand Commonly Spliced Genes in Human Chromosome 1 II: Expression Pattern and Gene Length Shape Codon Usage

进一步研究基因表达水平和基因长度与密码子使用偏爱之间的关系。多变量统计分析发现,人类1号染色体选择性剪接基因和普通剪接基因密码子使用变化都呈现单一趋势,且它们之间的密码子使用模式也非常相似,推测的高表达基因确实偏爱以C或G结尾的密码子,基因表达水平与密码子使用偏爱之间的关联也达到显著水平。因此,人类1号染色体高表达基因密码子的使用偏爱可能主要被翻译选择所决定。此外,基因长度与密码子偏爱水平之间也存在高度相关,说明相对较短的基因具有较高的密码子使用偏爱,翻译选择可能缩短了高表达基因的长度从而提高翻译效率。We further explored the correlation between synonymous codon bias and gene expression level and gene length. Correspondence analysis showed that there was only a single trend in codon usage variation among alternatively and commonly spliced genes, and the pattern of codons usage was very similar in them. The putatively highly expressed genes preferred C- or G-ending codons, and the correlations between synonymous codon bias and gene expression levels were also very significant, which implied that translation selection might play an important role in dominating codon usage bias in highly expressed genes in humans. Surprisingly, a strong correlation between codon-usage bias and gene length was also observed, e.g. the shorter a gene′s length, the higher its expression capacity. It suggested that the selection of codons might result in the reduction of the length of highly expressed genes and enhancement of translational efficiency.Chinapostdoctoralprogramsfoundation( 2 0 0 2 11

Synonymous Codon Usage of Both Alternativelyand Commonly Spliced Genes in Human Chromosome 1 I: Synonymous Codon Usage Bias Analysis

人类1号染色体可变剪接(选择性剪接)基因344非冗余蛋白质编码序列(188183密码子)和普通剪接(非可变剪接)基因的386蛋白质编码序列(223116密码子)被用于研究人类密码子使用偏爱模式。全部密码子使用数据分析表明,人类可变剪接基因密码子的偏爱水平显著高于普通剪接基因。在人类1号染色体基因中,密码子第三位置的G+C含量有很大的异质性(0 24～0 95),并且可变剪接基因密码子第三位置平均G+C含量(64 66%)大于普通剪接基因(59 97%)。Nc值对GC3s图显示密码子偏爱使用除了受核苷酸组成制约外,其它的因子可能也影响密码子的使用变化。此外,可变剪接基因中以G或C结尾的密码子比普通剪接基因出现的频率高。密码子使用的差异可能是由可变剪接基因pre mRNA特有的结构特征和多种剪接模式决定的。It is already clear that alternative splicing has an extremely important role in expanding the protein diversity. Comparative study of the codon usage patterns of alternatively and commonly spliced genes may thereby be necessary. In this paper, the patterns of codon usage bias of two kinds of human genes, alternatively spliced genes and commonly spliced genes, were formulated through analyzing 344 non-redundant protein coding sequences from alternatively spliced genes (188183 codons) and 386 from commonly spliced genes (223116 codons) in human chromosome (1. Overall) codon usage data analysis indicated that the alternatively spliced genes showed a stronger codon usage bias than commonly spliced genes. Very extensive heterogeneity of G+C content in silent third codon position (GC3s) was evident among these genes, and GC3s content of alternatively spliced genes was higher than that of commonly spliced genes. G- or C-ending codons were more abundant in alternatively spliced genes than commonly spliced genes in human chromosome 1. The causation of differences created could be explained by pre-mRNA structural characteristics of alternatively spliced genes influencing their codon usage bias.Chinapostdoctoralprogramsfoundation( 2 0 0 2 11

基于弹性悬链线理论的车组链输送机输送带张力变化特性研究

车组链输送机是一种新研发的散状物料连续性输送设备，相比通用带式输送机，其承载构件——输送带具有整机运行时张力较小的特点；基于弹性悬链线理论，对新型的车组链输送机输送带张力变化规律进行研究，建立输送带张力变化的理论模型，并推导得到车组链输送机运行时的输送带传动牵引力表达式。实例结果证明了悬链线理论应用于该场合的正确性

一种旋转平移一体化机械装置的工作机理分析

设计了一种旋转平移一体化机械装置，对装置的结构、原理、主要部件做了详细介绍，对机构的受力进行了分析。将该装置应用到绞车上，进行相关的选型设计，解决了绞车钢丝绳乱绳、咬绳等问题。通过UG建立了机构的三维模型，结合Adams对旋转平移一体化机构进行运动学仿真分析，得到了主要部件的转速、速度和位移图，并通过与理论计算的数值相比较，得出机构可以满足功能要求，验证了机构的可行性与运行的准确性

基于SIMPACK的车组链输送机轨道车组曲线通过性能研究

车组链输送机是一种新型的散状物料连续性输送设备。针对输送机关键结构中承载输送带并依托轨道运行的连续轨道车组在曲线工况处的曲线通过性能展开了研究。建立轨道车组曲线通过时的非线性动力学模型并进行分析。利用多体动力学仿真软件SIMPACK建立轨道车组模型，从不同的工况条件和轨道小车结构出发，分析轨道车组的曲线通过性能的变化。仿真结果表明，车组链输送机轨道车组在各工况下的动力学性能评价指标随着车速、车间距提高而减小，随曲线半径、缓和曲线长度的提高而增大；采用较小轴距轮对和铰接结构车体能够适应曲线轨道；轨道车组的曲线通过性能良好，各项指标都处于安全限度范围值之内

固载化离子液体催化碳酸乙烯酯水解制备乙二醇

采用溶胶-凝胶法制备了以SiO2为载体的固载化离子液体催化剂，并将其首次用于催化碳酸乙烯酯（EC）水解制备乙二醇（EG）的反应．结果表明，固载化碱性离子液体S-bpimHCO3对碳酸乙烯酯水解制EG反应具有良好的催化活性和EG选择性，克服了非均相催化剂活性不高与均相催化剂难以分离的不足．在催化剂浓度为0．0511edmL、温度140℃、压力0．4MPa及EC／H2O=1：2（摩尔比）、反应时间3h的条件下，EC转化率达99．7％，EG选择性为100％．该催化剂在循环使用5次后，EC转化率无明显下降，EG的选择性始终接近100％

固载化离子液体催化碳酸乙烯酯水解制备乙二醇

采用溶胶-凝胶法制备了以SiO2为载体的固载化离子液体催化剂,并将其首次用于催化碳酸乙烯酯(EC)水解制备乙二醇(EG)的反应.结果表明,固载化碱性离子液体S-[bpim][HCO3]对碳酸乙烯酯水解制EG反应具有良好的催化活性和EG选择性,克服了非均相催化剂活性不高与均相催化剂难以分离的不足.在催化剂浓度为0.0511g/mL、温度140℃、压力0.4MPa及EC/H2O=1:2(摩尔比)、反应时间3h的条件下,EC转化率达99.7%,EG选择性为100%.该催化剂在循环使用5次后,EC转化率无明显下降,EG的选择性始终接近100%