美白从来不是难事

美白从来都是亚洲女性的护肤终极追求目标,这一点甚至可以追溯历史直到先秦,民间更有一白遮百丑的俗语流传至今。宋玉在《登徒子好色赋》中就曾写道:眉如翠羽,肌如白雪,腰如束素,齿如含贝。看看,美男子宋先生真不愧是当年的偶像派,引领美白、纤体、烤瓷牙的风潮,直到今天咱们21世纪的女性还是这点追求。     

Aging. It's never too late

When organisms as diverse as yeast and rodents are subjected to a restricted diet, they live longer. The good news is, according to Vaupel, Carey, and Christensen in their Perspective, that switching to a restricted diet at any age can yield the benefit of increased longevity--at least in flies (Mair et al.).     

Molecular electronics. It's all about contacts

A key requirement in molecular electronics studies is the ability to measure the conductivity of a single molecule. But as Hipps explains in his Perspective, such measurements are often more about contacts than about molecular conductivity. Depending on the experimental setup, DNA behaves like a semiconductor, insulator, or metal. Cui et al. have designed a method that overcomes some of these problems, opening the door to systematic, reliable, and reproducible studies of the molecule-contact interface.     

转Cry1Ia基因抗虫大豆对鳞翅目靶标害虫的抗性分析

以转Cry1Ia基因抗虫大豆株系KE1为试验材料,分析其遗传稳定性及鳞翅目靶标害虫抗性,计算实验室内和田间环境下,甜菜夜蛾、斜纹夜蛾、黏虫和大豆食心虫叶面积损失率、幼虫平均校正死亡率、平均体重抑制百分率和虫食率.结果表明,KE1株系中目的基因Cry1Ia和标记基因Bar在T3～T5代中连续三代稳定遗传.KE1对靶标害虫...     

Cry1Ia和Cry2Ab杂交分子的构建和表达

同源性较低的Cry杀虫蛋白之间的结构域交换突变体成功案例很少。选择2种氨基酸同源性很低且蛋白其他特点差异也较大的Cry2Ab和Cry1Ia为亲本,将它们的3个结构域(Domain I,II和III)互换,构建6种结构域交换突变体。将这些突变体在Bt菌株中表达,分析其表达稳定性,并比较不同温度条件下的表达情况。结果显示,6种突变体在28.5,32.0℃条件下,均能够稳定表达,且表达量较高。说明构建的6种突变体在Bt菌株中具有较好的表达稳定性,以此为基础可以进一步检测其杀虫活性等特性。     

Breakthrough of the year. It's all about me

Along with the flood of discoveries in human genetics, 2007 saw the birth of a new industry: personal genomics. But researchers worry that these services open up a Pandora's box of ethical issues.     

A Fragment of Cadherin-Like Protein Enhances Bacillus thuringiensis Cry1B and Cry1C Toxicity to Spodoptera exigua（Lepidoptera：Noctuidae）

Cry toxins produced by Bacillus thuringiensis (Bt) are effective biological insecticides against certain insect species.In this study,bioassay results indicated that CrylB and Cry1C were toxic to Spodo...     

等价无穷小的性质及其在极限运算中的应用

利用等价无穷小代换求极限可以简化运算,但在现今教材中,只给出了等价无穷小在积商极限运算中的运用,基于此,从极限式中含有加减关系,复合结构,变上限积分结构及常见的0/0,∞/∞,1∞,00∞0结构进行讨论,最后,给出了相应的等价无穷小代换的定理和应用实例.     

两种转Bt基因棉杀虫蛋白Cry1Ac表达量的检测

用EnvirologixCry1Ab/Cry1Ac平板试剂盒检测了两种转Cry1Ac基因的棉花品系 (NUCOTN33B、NUCOTN99B) 以及常规对照品系 (苏棉 12) 不同生育期主茎嫩叶、侧枝嫩叶、蕾及蕾的苞叶中杀虫蛋白Cry1Ac的含量。结果表明, 两种转Bt基因棉主茎嫩叶杀虫蛋白Cry1Ac的含量随生育期的推移呈明显下降趋势, 花铃期 (NUCOTN33B和NUCOTN99B分别为 4 43和 2 93μg·g-1 ) 和吐絮期 (3 87和 2 86μg·g-1 ) 的含量分别降至苗期第 6叶 (7 64和 8 38μg·g-1 )的 58%、35%和 51%、34%; 相同时期的主茎嫩叶和侧枝嫩叶中Cry1Ac的含量均显著高于蕾及蕾的苞叶, 前两者均为后两者的两倍以上。