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991.
Genomic imprinting, representing parent-specific expression of alleles at a locus, is mainly evident in flowering plants and
placental mammals. Most imprinted genes, including numerous non-coding RNAs, are located in clusters regulated by imprinting
control regions (ICRs). The acquisition and evolution of genomic imprinting is among the most fundamental genetic questions.
Discoveries about the transition of mammalian imprinted gene domains from their non-imprinted ancestors, especially recent
studies undertaken on the most ancient mammalian clades — the marsupials and monotremes from which model species genomes have
recently been sequenced, are of high value. By reviewing and analyzing these studies, a close connection between non-coding
RNAs and the acquisition of genomic imprinting in mammals is demonstrated. The evidence comes from two observations accompanied
with the acquisition of the imprinting: (i) many novel non-coding RNA genes emerged in imprinted regions; (ii) the expressions
of some conserved non-coding RNAs have changed dramatically. Furthermore, a systematical analysis of imprinted snoRNA (small
nucleolar RNA) genes from 15 vertebrates suggests that the origination of imprinted snoRNAs occurred after the divergence
between eutherians and marsupials, followed by a rapid expansion leading to the fixation of major gene families in the eutherian
ancestor prior to the radiation of modern placental mammals. Involved in the regulation of imprinted silencing and mediating
the chromatins epigenetic modification may be the major roles that non-coding RNAs play during the acquisition of genomic
imprinting in mammals.
Supported by National Natural Science Foundation of China (Grant No. 30830066), the Ministry of Education of China and Natural
Science Foundation of Guangdong Province (Grant No. IRT0447, NSF-05200303) and National Key Basic Research and Development
Program of China (Grant No. 2005CB724600) 相似文献
992.
993.
Hua Zhang Jian-Hua Yang Yu-Sheng Zheng Peng Zhang Xiao Chen Jun Wu Ling Xu Xue-Qun Luo Zhi-Yong Ke Hui Zhou Liang-Hu Qu Yue-Qin Chen 《PloS one》2009,4(9)
Background
MicroRNAs (miRNAs) have been proved to play an important role in various cellular processes and function as tumor suppressors or oncogenes in cancers including leukemia. The identification of a large number of novel miRNAs and other small regulatory RNAs will provide valuable insights into the roles they play in tumorgenesis.Methodology/Principal Findings
To gain further understanding of the role of miRNAs relevant to acute lymphoblastic leukemia (ALL), we employed the sequencing-by-synthesis (SBS) strategy to sequence small RNA libraries prepared from ALL patients and normal donors. In total we identified 159 novel miRNAs and 116 novel miRNA*s from both libraries. Among the 159 novel miRNAs, 42 were identified with high stringency in our data set. Furthermore, we demonstrated the different expression patterns of 20 newly identified and several known miRNAs between ALL patients and normal donors, suggesting these miRNAs may be associated with ALL and could constitute an ALL-specific miRNA signature. Interestingly, GO “biological process” classifications revealed that a set of significantly abnormally expressed miRNAs are associated with disease relapse, which implies that these dysregulated miRNAs might promote the progression of ALL by regulating genes involved in the pathway of the disease development.Conclusion/Significance
The study presents a comprehensive picture of the expression of small RNAs in human acute lymphoblastic leukemia and highlights novel and known miRNAs differentially expressed between ALL patients and normal donors. To our knowledge, this is the first study to look at genome-wide known and novel miRNA expression patterns in in human acute lymphoblastic leukemia. Our data revealed that these deregulated miRNAs may be associated with ALL or the onset of relapse. 相似文献994.
995.
目的:研究孤啡肽(N/OFQ)对大鼠顶叶皮层神经元瞬时外向钾电流(IA)的影响,初步探讨其作用的通道动力学机制。方法:采用全细胞膜片钳技术,观察N/OFQ对急性分离的大鼠顶叶皮层神经元IA的作用。结果:①0.1μmol/L N/OFQ使IA幅值由给药前的(5356.1±361.6)pA下降为(4113.3±312.7)pA,抑制率为23.20%±2.17%(P〈0.01,n=10)。②0.1μmol/L N/OFQ使IA的电流-电压(I-V)曲线降低(P〈0.01,n=10)。③0.1μmol/L N/OFQ使,IA激活曲线的半数激活电压(V1/2)和斜率因子(κ)分别由给药前的(-9.2±2.5)mV和(20.4±2.3)mV变为给药后的(30.6±3.7)mV(P〈0.01,n=8)和(22.6±2.1)mV(P〉0.05,n=8)。④0.1μmol/L N/OFQ使IA失活曲线的半数失活电压(V1/2)和斜率因子(κ)分别由给药前的(-64.1±3.2)mV和(21.5±2.1)mV变为给药后的(-55.9±1.9)mV(P〈0.05,n=5)和(19.6±2.2)mV(P〉0.05,n=5)。结论:N/OFQ可抑制大鼠顶叶皮层神经元IA,使其激活曲线、失活曲线均右移。 相似文献
996.
旨在研究蛋白G IgG Fc段结合域(PGFB)的克隆、表达及其抗体结合功能,用于抗体的纯化.根据PGFB的氨基酸序列,选择大肠杆菌偏爱的密码子,设计并合成了4个寡核苷酸片段.通过重叠延伸PCR方法合成了PGFB DNA片段,测序鉴定后克隆至原核表达系统pET-28a-c(+)上,转化大肠杆菌,获得表达菌株;IPTG诱导表达PGFB,经Ni+-NTA琼脂糖凝胶层析纯化后偶联到琼脂糖凝胶6B上,用其纯化多克隆抗体.结果显示,PGFB在大肠杆菌BL21(DE3)中获得高效表达,纯化后纯度达到90%以上,相对分子量为12.25 kD,与预期值相符.此外,偶联产物纯化多克隆抗体达到了良好的效果,每毫升基质可结合20 mg抗体.本研究克隆构建并高效表达了具有较好抗体亲和能力的PGFB,为多克隆抗体的快速纯化提供了方便. 相似文献
997.
998.
999.
Huan Zhang Yong-an Zhang Qilian Qin Xuan Li Lin Miao Yuzhu Wang Liangjian Qu Aijun Zhang Qing Yang 《In vitro cellular & developmental biology. Animal》2009,45(5-6):201-204
A cell strain (IOZCAS-Spex-II-A) cloned from IOZCAS-Spex-II, a cell line established from the fat body of Spodoptera exigua (Lepidoptera: Noctuidae) larva, was characterized, and its capability to produce S. exigua nucleopolyhedrovirus was high with infection rate exceeding 90% compared with its parental cell line IOZCAS-Spex-II that scored only 50%. Growth curve of budded virus (BV) in the strain was analyzed and the titer of BV reached the highest of 3.7?×?104 pfu/mL by 96 h after inoculation. Concentration of occlusion bodies (OBs) produced by the cloned cell strain (IOZCAS-Spex-II-A) was 7.1?×?107 OBs/mL, while the parental cell line produced 2.4?×?107 OBs/mL. The average yield of the virus was 176 OBs/cell of IOZCAS-Spex-II-A compared with 211 OBs/cell that of the parental cell line. Significant differences were observed in virus production, growth characters, cell shape, between the parental cell line, and its clone. The cell lines (IOZCAS-Spex-II and IOZCAS-Spex-II-A) were also susceptible to Autographa californica multiple nucleopolyhedrovirus infection. In addition, they were characterized with regard to their growth rates and DNA amplification fingerprinting technique employing polymerase chain reaction. 相似文献
1000.