基因组内碱基分布整体均衡与局部不均衡的研究进展

近年来,随着各种基因组计划的相继完成,发现在各种生物体单核苷酸链水平上存在着A≌T,G≌C的数量关系,但从几千个至十几万个碱基的范围来看,A≠T,G≠C。从数学上可以证明,如果DNA双链之间碱基的突变率一致,则A≌T,G≌C成立,但很多实验表明,双链之间的突变率并不一致,因此这个问题的解决仍有赖于数理科学和生物学的进一步结合。 Abstract:With more and more genome have been completely sequenced,scientists find the Partial Rule 2(PR2) in entire single strand that A≌T,G≌C.But from the scope of thousands to hundreds of thousand bases,A≠T,G≠C.Form the view of math,if the mutational rate of one strand is equal to others,it could be proved that A≌T,G≌C,but from the view of experience,that premise doesn't exist,so the solution of the problem needs the deeply combination of biology and math.     

Rosmarinic acid and siRNA combined therapy represses Hsp27 (HSPB1) expression and induces apoptosis in human glioma cells

High expression of Hsp27 in glioma cells has been closely associated with tumor cell proliferation and apoptosis inhibition. The aim of the present study was to asses the effects of rosmarinic acid (RA) on Hsp27 expression and apoptosis in non-transfected and transfected human U-87 MG cells. The effect of rosmarinic acid was compared to quercetin, which is known to be a good Hsp27 inhibitor. In order to block the expression of Hsp27 gene (HSPB1), transfection with specific siRNAs was performed. Western blotting technique was used to assess the Hsp27 expression, and caspase-3 colorimetric activity assay was performed to determine apoptosis induction. According to the results, it was found that RA and quercetin effectively silenced Hsp27 and both agents induced apoptosis by activating the caspase-3 pathway. Eighty and 215 μM RA decreased the level of Hsp27 by 28.8 and 46.7% and induced apoptosis by 30 and 54%, respectively. For the first time, we reported that rosmarinic acid has the ability to trigger caspase-3 induced apoptosis in human glioma cells. As a result of siRNA transfection, the Hsp27 gene was silenced by ~?50% but did not cause a statistically significant change in caspase-3 activation. It was also observed that apoptosis was induced at a higher level as a result of Hsp27 siRNA and subsequent quercetin or RA treatment. siRNA transfection and 215 μM RA treatment suppressed Hsp27 expression level by 90.5% and increased caspase-3 activity by 58%. Herein, we demonstrated that RA administered with siRNA seems to be a potent combination for glioblastoma therapy.     

How visual stimulus effects the time perception? The evidence from time perception of emotional videos

Time perception is defined as a subjective judgment on the elapsed time of an event. It can change according to both external and internal factors. There are two main paradigms of time perception; retrospective time perception (RTP) and prospective time perception (PTP). Two paradigms differ from each other according to whether the subject has knowledge on the importance of passage of time in the given task. Since RTP paradigm studies are harder to conduct, studies on RTP paradigm is far fewer than studies on PTP. Thus in the current study, both RTP and PTP paradigms are investigated. Also, time perception is discussed in relation to internal clock model and cognitive load. Emotional motion videos are used to create cognitive load and manipulate internal clock. Results showed the effect of emotion on time perception. Another major finding is that shorter videos are perceived longer whereas longer videos are perceived shorter as in accordance with Vierordt’s Law. However, there was no difference between RTP and PTP paradigms. These results indicate that emotional videos change our internal clock while a number of changes in a motion video create cognitive load causing disturbance of time perception.     

EPO modified MSCs can inhibit asthmatic airway remodeling in an animal model

There was no effective measures can be obtained at present to reverse or prevent airway remodeling. We investigated the therapeutic effect of Erythropoietin (EPO) gene modified mesenchymal stem cells (MSCs) on asthmatic airway remodeling and the possible underlied molecular mechanisms. EPO gene was transfected into MSCs via lentivirus vector. The transfected cells (EPO‐MSCs) were identified by flow cytometry and the EPO secreting function was detected by PCR and Western blot. MSCs or EPO‐MSCs were administrated to albumin (OVA)‐induced chronic asthmatic mouse model via tail veins. The asthmatic phenotype was analyzed. Number of cells in bronchoalveolar lavage fluid (BALF) was counted using a hemocytometer. Histological findings of airways were evaluated by microscopic examination. The concentrations of interleukin 4(IL‐4), interleukin 5(IL‐5), and interleukin 13(IL‐13) in lung homogenate were determined by ELISA. The activation state of transforming growth factor‐β 1 (TGF‐β1), Transforming growth factor beta‐activated kinase 1 (TAK1), and p38 Mitogen Activated Protein Kinase (p38MAPK) signaling was detected by Real‐Time PCR and Western blotting. EPO‐MSCs were successfully constructed. EPO‐MSCs showed a more potently suppressive effect on local asthmatic airway inflammation and the level of IL‐4, IL‐5, and IL‐13 in lung tissue than MSCs. Moreover, the numbers of goblet cells, the thicknesses of smooth muscle layer, collagen density, percentage of proliferating cell nuclear antigen positive (PCNA⁺) mesenchymal cells, and von Willebrand factor positive(vWF⁺) vessels were also significantly inhibited by EPO‐MSCs. Furthermore, EPO‐MSCs could downregulate the expression of TGF‐β1, TAK1, and p38MAPK in lung tissue both in mRNA level and in protein level. EPO gene modified MSCs may more efficiently attenuate asthmatic airway remodeling, which maybe related with the downregulation of TGF‐β1‐TAK1‐p38MAPK pathway activity.     

烟草传粉前后生殖器官中细胞分裂素含量的变化

经免疫亲和层析系统纯化后,用间接竞争ＥＬＩＳＡ 法测定了烟草（Ｎｉｃｏｔｉａｎａ ｔａｂａｃｕｍ ）生殖器官在传粉前后细胞分裂素（ｔ－ＺＲ,ｉＰＡ）含量的变化． 开花前５ ｄ,花药和花丝中的细胞分裂素（ＣＴＫ）含量均达到最高值,以后随雄蕊发育逐渐下降． 授粉使花柱ＣＴＫ 含量急剧上升,授粉后１ ｄ 达到高峰,未经受粉的花柱ＣＴＫ 开花后下降．授粉后２ ｄ,子房中的ＣＴＫ 开始上升,在授粉后４ ｄ 达到最高值,而未受精的子房ＣＴＫ 含量开花后下降． 传粉后雌蕊中ＣＴＫ含量随花粉管生长而有规律地增加,ＣＴＫ 积极参与植物的传粉和受精过程     

The roles of polyamines in microorganisms

Polyamines are small polycations that are well conserved in all the living organisms except Archae, Methanobacteriales and Halobacteriales. The most common polyamines are putrescine, spermidine and spermine, which exist in varying concentrations in different organisms. They are involved in a variety of cellular processes such as gene expression, cell growth, survival, stress response and proliferation. Therefore, diverse regulatory pathways are evolved to ensure strict regulation of polyamine concentration in the cells. Polyamine levels are kept under strict control by biosynthetic pathways as well as cellular uptake driven by specific transporters. Reverse genetic studies in microorganisms showed that deletion of the genes in polyamine metabolic pathways or depletion of polyamines have negative effects on cell survival and proliferation. The protein products of these genes are also used as drug targets against pathogenic protozoa. These altogether confirm the significant roles of polyamines in the cells. This mini-review focuses on the differential concentrations of polyamines and their cellular functions in different microorganisms. This will provide an insight about the diverse evolution of polyamine metabolism and function based on the physiology and the ecological context of the microorganisms.     

Retracted: CYP2E1 Rsa Ι/Pst Ι polymorphism and lung cancer susceptibility: a meta‐analysis involving 10,947 subjects

Many studies have examined the association between the CYP2E1 Rsa Ι/Pst Ι (rs3813867) polymorphism gene polymorphisms and lung cancer risk in various populations, but their results have been inconsistent. The PubMed and CNKI database was searched for case–control studies published up to October 2013. Data were extracted and pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated. In this meta‐analysis, we assessed 23 published studies involving comprising 4727 lung cancer cases and 6220 controls of the association between CYP2E1 Rsa Ι/Pst Ι polymorphism and lung cancer risk. For the homozygote c2/c2 and c2 allele carriers (c1/c2 + c2/c2), the pooled ORs for all studies were 0.73(95% CI = 0.62–0.84; P = 0.005 for heterogeneity) and 0.84 (95% CI = 0.77–0.92; P = 0.001 for heterogeneity) when compared with the homozygous wild‐type genotype (c1/c1). In the stratified analysis by ethnicity, the same significantly risks were found among Asians and mixed population for both the c2 allele carriers and homozygote c2/c2. However, no significant associations were found in Caucasian population all genetic models. This updated meta‐analysis suggests that CYP2E1 Rsa Ι/Pst Ι c2 allele is a decreased risk factor for the developing lung cancer among Asians and mixed population.     

Analysis of the electroencephalographic activity during the Necker cube reversals by means of the wavelet transform

In previous studies, a perceptual switching related potential was obtained during the observation of a multistable dynamic reversal pattern, where the averaging of the single responses was triggered by subjects pressing a button. The present methodological study aims to increase the signal quality of perceptual switching related potentials considering the dependence of the measurement method on the reaction time of the subject, which may vary significantly during a session, leading to low-amplitude waveform in the averaged event-related-potential (ERP). To overcome this problem in measuring the electrophysiological correlate of an internal event, a pattern selection method based on the wavelet transform (WT) is proposed to choose a subset of single ERPs with more homogenous latencies. Nine subjects observed a Necker cube and were instructed to press the button immediately after perceptual switching. A slow, low-amplitude positive wave with frontocentral amplitude maxima was observed around 250 ms prior to the button press. After the application of a 5 octave WT on single sweeps, the time-frequency coefficients obtained in each octave were averaged across trials. The most dominant feature representing the averaged ERP was the delta (0.5–4 Hz) coefficient occurring between 250 and 125 ms before the button press. By averaging the subset of the single sweeps containing this property, a sharpening and significant amplitude increase of the response peak was observed. Received: 12 September 1997 / Accepted in revised form: 9 July 1998     

菜豆下胚轴中的细胞分裂素结合蛋白

用植物体内天然存在并具有很高活性的玉米素（ｔ－Ｚ）和异戊烯基腺苷（ｉＰＡ）作为配基,分别与Ｓｅｐｈａｒｏｓｅ－４Ｂ偶联,制成亲和吸附介质,分离、纯化菜豆（Ｐｈａｓｅｏｌｕｓ ｖｕｌｇａｒｉｓ）黄化幼苗下胚轴中的细胞分裂素结合蛋白。一种分子量为１５．５ ｋＤ（简称ＺＢＰ）,只含一个多肽链;另一种分子量为１６５ ｋＤ（简称ＩＢＰ）,含有两种亚基,分子量分别为４３ ｋＤ和４０ ｋＤ。对ＺＢＰ的结合活性进行了研究,发现ＺＢＰ与ｔ－Ｚ结合时的解离常数（Ｋｄ）为３．２×１０－ ７ ｍ ｏｌ／Ｌ。经计算,每个ＺＢＰ分子只有一个ｔ－Ｚ结合位点