当前癌症研究三大热点

此次《科学》杂志纪念癌症行动法案40周年专题文章的一大特点是请到了一批活跃在癌症研究一线的知名科学家撰文，对癌基因组计划、癌细胞转移、癌症免疫编辑等当今癌症研究领域的前沿课题或方向作了介绍。     

个人基因测序有多远

基因测序技术不但能锁定个人病变基因,还能提做到提前预防和治疗。但有专家担心这些全基因检测普及,一旦落入保险公司或者被测者雇主的手中,将会对人们的生活产生不良影响。     

灵芝基因组框架图已经完成

《自然通讯》(Nature Communications)6月报道,有着"不死药"美誉的中国仙草——灵芝(Ganoderma lucidum),其基因组框架图已于近日绘成。该项目由中国医学科学院药用植物研究所、美国田纳西州大学健康科学中心和威斯康星大学麦迪逊分校等机构的研究人员联合完成,通讯作者是中国医学科学院药用植物研究所的陈士林所长和孙超博士。灵芝,不仅在中国久负盛名,在世界范围内也是众所周知的一种药用大     

Accurate localization and excision of genomic islands in four strains of <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> and <Emphasis Type="Italic">Pseudomonas fluorescens</Emphasis>

Mobile genomic islands (GIs) can be excised from the chromosome, then form a circular intermediate and be reintegrated into the chromosome by the GI internal integrase. Some mobile GIs can also be transferred into a new receptor cell by transformation, conjugation, or transduction. The action sites of the integrase are usually flanked direct repeats (DRs) of the GIs. Accurate localization of the flanking sequences is a precondition for determining the mobility of the GI. Mobile GIs are generally associated with transfer RNAs (tRNAs). Based on the correlation between flanking sequences and tRNA sequences, the flanking sequences of 11 putative mobile GIs in Pseudomonas aeruginosa PAO1, P. aeruginosa PA14, P. fluorescens Pf-5 and P. fluorescens Pf0-1 were identified. Among the 11 GIs, Pf0-1GI-1 is responsible for benzoate degradation. PAO1GI-1, Pf5GI-2, Pf5GI-3, and Pf5GI-4 were confirmed experimentally to be excised from a chromosome to form a circular intermediate. The action sites of the integrases are these GIs direct repeats. Due to distinct DRs, cutting sites for the internal integrase of PAO1GI-1, Pf5GI-2, Pf5GI-3 and Pf5GI-4 were determined outside the T-loop of the tRNA^Gly gene, outside the anticodon loop of the tRNA^Ser gene and tRNA^Lys gene, and at the asymmetric 3′-end of the tRNA^Leu gene, respectively. PAO1GI-1 and other mobile GIs may be transferred into many different strains that belong to different phyla because of the clear flanking sequences. This study describes basic information about the action sites of the integrases, assesses the mobility of GIs, and can help design and transfer mobile GIs to candidate strains.     

DNA damage,signaling and repair: Protecting genomic integrity and reducing the risk of human disease

DNA is the genetic material that contains the "instructions" to not only guide the continuation of life but also govern the development, metabolism and functioning of living organisms. DNA damage occurs daily due to various exogenous (environ-     

走向人造生命的努力

2010年5月20日美国《科学》杂志报道，两位美国生物学家文特尔（Craig Venter）和史密斯（Hamilton Smith）成功制造出首例由人工合成基因组所控制的单细胞生物体——地球上本不存在的蕈状支原体（Mycoplasma mycoides）新种株，呢称“辛西娅”（Synthia）。     

药皮组分对不锈钢焊条工艺性能的影响规律

焊条药皮成分对不锈钢焊条工艺性能有较大的影响。通过对近百种焊条的药皮组分进行调配，发现碳酸盐与氯化物的比值对稳弧性、焊接飞溅以及焊缝成型等性能的影响很大。TiO2与硅铝酸盐之比应不小于3．5：1，以防止出现粘渣。加入硅、钛等强脱氧剂会显著改善焊条的脱渣性能。药皮厚度对焊条工艺性能也有较大的影响。药皮厚度越大，焊接飞溅率越低，脱渣性能越好。     

嗜碱和耐盐碱放线菌的细胞组分分析

本文对49株嗜碱和耐盐碱放线菌的细胞组分,形态学、生长pH和耐盐性进行了研究。22株菌为嗜碱菌,其余27株为耐碱菌,除两株菌外,都能耐受4％的NaCl,41株能耐受7%、17株能耐受10％,3株可耐受15％的 NaCl。37株菌为Ⅰ型细胞壁.全细胞水解液无特征性糖,其余12株菌的胞壁组分出现异常,出现meso-DAP和Gly。其中两株菌仅出现meso-DAP和Gly,4株菌出现迹量的迹量的L-DAP,两株菌的meso-DAP比L—DAP少.4株菌两种类型的DAP含量相近。     

C─值悖论及其机制

基因组大小，即Ｃ值，与基因组中所含的遗传信息的认定数量间缺乏对应，这种Ｃ一值悖论是由非基因ＤＮＡ的增加所造成的．     

用催化动力学分析法同时测定多种组分

多种催化剂催化同一指示反应时，如果其反应的表观机理不同，则可由一次实验同时测定这几种催化剂，文中以锇和碘的两元体系例，以Ｃｅ（Ⅵ）氧化Ａｓ（Ⅲ）作为指示反应，研究了这两种组分的同时测定方法，用光度法测量Ｃｅ（Ⅵ）浓度随时间的变化，然后用Ｓａｖｉｔｚｋｙ－Ｇｏｌａｙ方法求出其反应速率，表观反应速率常数及反应级数可用线性回归法求出，并用两元线性因归计算锇和碘的浓度。