Forced expression of theOct-4 gene influences differentiation of embryonic stem cells

By transfecting an Oct-4 expression plasmid into embryonic stem cells (ES cells), the ES-O cell line was constructed, which sustained the expression of Oct-4 gene when induced by retinoic acid. Forced expression of Oct-4 gene could not sustain the stem property of ES-O cells without the differentiation inhibiting factor LIF, but if LIF exists, forced expression of Oct-4 gene could enhance the ability to sustain the undifferentiation state and inhibit cell differentiation induced by retinoic acid. It was indicated that Oct-4 must cooperate with LIF to sustain the undifferentiation state of ES cells. During the cell differentiation, ES-O cells tend to differentiate into neural cells, suggesting that forced expression of Oct-4 gene may be in relation with the differentiation of neuroderm.     

Deletion of immunoglobulin heavy chain genes from expressed allelic chromosome

We have studied the organization of immunoglobulin heavy-chain genes in a gamma 2b-chain (BALB/c allotype)-producing myeloma BKC F1 # 15 induced in a F1 mouse between C57BL and BALB/c. Southern blot hybridization studies using cloned mu, gamma 1 and gamma 2b-chain genes as probes demonstrate that the mu- and gamma 1-chain genes of the expressed chromosome are deleted while these genes of the unexpressed chromosome are retained. The gamma 2b-chain gene of the expressed allele is rearranged while that gene of the unexpressed allele seems unchanged, as do the gamma 2a-chain genes. These results support the allelic deletion mechanism in heavy-chain class switch and the order of H chain genes.     

甲基乙二醛诱导牙周膜成纤维细胞基因表达与分析

运用基因芯片研究甲基乙二醛诱导人牙周膜成纤维细胞基因表达谱的变化。原代培养人牙周膜成纤维细胞,诱导组以终质量浓度为0.1 g/L的甲基乙二醛刺激培养细胞,对照组不含甲基乙二醛。24 h后收获细胞,提取mRNA,逆转录cDNA时用Cy3和Cy5荧光染料标记,制备成cDNA探针,与表达谱芯片进行杂交、扫描和分析。芯片检测结果用实时定量聚合酶链反应验证和生物信息学分析。结果共有18条基因显著差异表达,其中上调基因有11条,下调基因有7条,差异性表达的基因按功能可分为程序性细胞死亡、信号转导、细胞因子、代谢酶类、载体蛋白和未知基因等。与程序性细胞死亡、信号转导和细胞因子相关基因的差异表达可能是甲基乙二醛通过线粒体信号通路,诱导人牙周膜成纤维程序性细胞死亡,破坏牙周组织增生,从而导致牙周病发生的机制。     

月季插穗不定根起始的转录组分析和关键基因筛选

为研究月季插穗在不定根发生过程中的关键基因调控机理,利用Illumina平台测序技术对切花月季品种‘卡罗拉’插穗的3个发育阶段(不定根未启动期、愈伤组织形成期和不定根伸长期)插穗基部1 cm皮层进行转录组测序分析,结果表明:月季插穗不定根发生的3个阶段中,在不定根未启动期与愈伤组织形成期之间共筛选出差异表达基因5 033个,其中2 313个基因上调,2 720个基因下调;在愈伤组织形成期与不定根伸长期之间共筛选出差异表达基因1 865个,其中1 332个基因上调,533个基因下调;GO功能分析表明,差异表达基因主要参与生物过程、分子功能和细胞组分3大功能;KEGG富集分析结果表明,差异表达基因主要参与植物激素信号转导、次生代谢产物的合成以及碳水化合物的合成等代谢通路;将月季插穗生根过程中差异性最为显著的8个基因通过实时荧光定量PCR检测其转录水平变化,结果表明: 实时荧光定量PCR的验证结果与转录组测序结果基本一致.     

杨树部分基因起始密码子AUG侧翼序列特征分析

对297条杨树基因序列的起始密码子AUG侧翼区序列(-20位点- 6位点)的碱基分布特性进行了统计学分析,并对高表达基因和低表达基因翻译起始位点侧翼序列碱基的保守性和关联性进行了对比分析。结果表明:紧邻起始密码子5′端的-1、-2、-3、-4、-5和-6位点均强烈偏好A, 4位点强烈偏好G,同时高表达和低表达基因的-20位到 4位中某些位点的保守性存在较大差异,其中高表达基因的-6,-3和 4位可能与其高表达的特性有关;通过关联性分析可以看出,在起始密码子侧翼序列的某些特定区域碱基之间的关联性可能也与翻译起始效率有关系;相关性分析表明低表达基因的AUGCAI主要受到"AUG"侧翼区序列的GC含量的影响,低表达基因在"AUG"侧翼区富集GC对翻译有一定影响。     

汉滩病毒S基因0.7kb片段与M基因G2片段不同拼接方式嵌合基因原核表达产物的初步比较

比较汉滩病毒S、M基因部分片段的嵌合基因不同拼接方式表达产物的活性。构建了嵌合基因原核表达载体pGEX-4T-1-S0.7G2,并与已构建的pGEX-4T-1-G2S0.7的诱导表达产物进行了比较。结果表明,融合蛋白同时保持亲本蛋白的结合活性,且前者表达产物的结合活性始终比后者低。研究表明,嵌合基因的不同拼接方式对融合蛋白的活性可能有一定的影响。     

Nested expression domains of four homeobox genes in developing rostral brain.

Insight into the genetic control of the identity of specific regions along the body axis of vertebrates has resulted primarily from the study of vertebrate homologues of regulatory genes operating in the Drosophila trunk, but little is known about the development of most anterior regions of the body either in flies or vertebrates. Three Drosophila genes have been identified that are important in controlling the development of the head, two of which, empty spiracles and orthodenticle, have been cloned and shown to contain a homeobox. We previously cloned and characterized Emx1 and Emx2, two mouse genes related to empty spiracles that are expressed in restricted regions of the developing forebrain, including the presumptive cerebral cortex and olfactory bulbs. Here we report the identification of Otx1 and Otx2, which are related to orthodenticle. We have compared the expression domains of the four genes in the developing rostral brain of mouse embryos at a developmental stage, day 10 post coitum, when they are all expressed. Otx2 is expressed in every dorsal and most ventral regions of telencephalon, diencephalon and mesencephalon. The Otx1 expression domain is similar to that of Otx2, but contained within it. The Emx2 expression domain is comprised of dorsal telencephalon and small diencephalic regions, both dorsally and ventrally. Finally, Emx1 expression is exclusively confined to the dorsal telencephalon. Thus at the time when regional specification of major brain regions takes place, the expression domains of the four genes seem to be continuous regions contained within each other in the sequence Emx1 less than Emx2 less than Otx1 less than Otx2.     

大肠杆菌编码区5′端碱基的统计分析

统计了大肠杆菌１２８８个编码序列开始的３３个碱基位点（１１个密码子）上各碱基出现的概率,发现第２、第３密码子各位点上的碱基概率分布与其它密码子上的碱基分布概率不一样;碱基Ｇ和Ｔ出现的概率从第４个密码子后呈现明显的３周期分布．我们还研究了这些位点上的碱基概率分布与基因表达水平的关系,发现高表达基因和低表达基因在第２、第３密码子各位点上,其各种碱基的概率分布是有区别的;高表达基因碱基Ｇ和Ｔ的概率分布３周期性更明显．     

乳腺癌-冠心病共享生物标志物筛选

运用生物信息学方法筛选乳腺癌-冠心病标志物,为乳腺癌诱发的冠心病治疗提供潜在的作用靶点.从基因表达数据库(gene expression omnibus,GEO)中下载乳腺癌和冠心病相关表达谱芯片数据,使用GEO2R筛选差异表达基因,依据Venn图交集获取差异共表达基因,通过DAVID网站进行基因功能注释(gene ontology,GO)及京都基因与基因组百科全书(Kyoto Encyclopedia of Genes and Genomes,KEGG)生物功能富集分析,STRING网站和Cytoscape 3.7.2软件进行蛋白互作分析.GE-PIA和Kaplan-Meier Plotter进行对乳腺癌患者hub基因mRNA表达水平和预后分析.结果表明:2个数据集筛选得到差异表达基因286个,基于在乳腺癌中mRNA显著性表达水平筛选出45个基因.GO功能富集分析发现差异表达基因主要在泛素蛋白转移酶活性、糖蛋白结合、泛素蛋白连接酶结合等生物学过程发挥作用.KEGG分析显示差异基因主要参与缝隙连接、肾素分泌、5-羟色胺能突触、谷氨酸能突触、血管平滑肌收缩、血小板活化、癌细胞蛋白多糖等多条信号通路.基因mRNA表达水平和预后分析显示NLN、POSTN、MAPT、MYO6、MAP1B、FBXO31、KIT、PIK3R1等8个与冠心病相关的hub基因参与乳腺癌的发生、发展过程.NLN、POSTN、MAPT、MYO6、MAP1B、FBXO31、KIT、PIK3R1可作为检测乳腺癌诱导冠心病的潜在标志物.     

大肠杆菌SD序列与基因表达水平的关系

依据基因表达水平的理论预测方法从１３７３个大肠杆菌基因中选出了７３个甚高表达基因和１００个甚低表达基因,研究了这两类基因编码区起始密码子ＡＴＧ前－１到－２１位点（包含ＳＤ序列）的碱基构成与基因表达水平的关系。结果表明,ＳＤ序列中的富嘌呤区（约在－７到－１２位点）Ｇ和Ｔ的概率分布曲线中心到ＡＴＧ的距离（记为ＬＨ）与基因表达水平有明显的关系。甚高表达基因ＬＨ约为１０,甚低表达基因的ＬＨ约为８,另外在－     

Transcript localization of four opsin genes in the three visual organs of Drosophila; RH2 is ocellus specific

Drosophila and other Dipteran flies have three different kinds of visual organs; in the adult a pair of compound eyes and three dorsal ocelli; and in the larva a pair of internal photoreceptor organs. They develop in distinct ways, yet have certain features in common. All three organs use retinal-derived chromophores, coupled to distinct opsins, to provide a diversity of spectral sensitivities. Four opsin genes have been identified thus far in Drosophila; Rh1, Rh2, Rh3 and Rh4 (refs 6-11). We have used in situ hybridization to study the messenger RNAs expressed by these four opsin genes in all three visual organs. Rh1, Rh3 and Rh4 are already known to be expressed in different subsets of cells in the compound eye. We found that, in contrast, opsin Rh2 is the predominant opsin expressed in the ocelli. Opsin Rh1 is known to be expressed in the larval photoreceptor. We found that Rh3 and Rh4 are as well, but not Rh2. The ocellar-specific gene expression of Rh2 is of particular interest for its possible bearing on the function of the ocellus.