As easy as flipping a switch?

Proteins that behave as switches help to establish the complex molecular logic that is central to biological systems. Aspiring to be nature's equal, researchers have successfully created protein switches of their own design; in particular, numerous and varied zinc-triggered switches have been made. Recent studies in which such switches have been readily identified from combinatorial protein libraries support the notion that proteins are primed to show allosteric behavior and that newly created ligand-binding sites will often be functionally coupled to the original activity of the protein. If true, this notion suggests that switch engineering might be more tractable than previously thought, boding well for the basic science, sensing and biomedical applications for which protein switches hold much promise.     

Cr和As复合污染对水稻幼苗吸收积累Fe,P,As和Cr的影响

通过水培实验,研究As和Cr复合污染在有磷(+P)和无磷(?P)条件下对2个水稻基因型品种(Jin23A和CDR22)生长和吸收积累Fe,P,As和Cr的影响.实验结果表明,As和Cr复合污染可导致水稻茎叶干重下降,但对株高、根长和根干重均影响不大.施P肥可促进水稻生长,提高水稻生物量,缓解水稻的重金属毒害.As和Cr复合污染对水稻植株吸收积累Fe,P,As和Cr的影响不一.加As和加P均导致两个水稻品种茎叶和根中Fe含量下降.As对水稻植株P含量影响不大.P可促进水稻根系对As的吸收,而降低水稻对Cr的吸收积累.加As导致水稻Cr含量提高,尤其水稻根系Cr含量提高更明显.与对照相比,1.0mg/LAs浓度在不加P时分别导致Jin23A和CDR22根系Cr含量提高138.9%和283.6%,加P时则分别为40.2%和154.1%.此外,本文还讨论了Fe,P,As和Cr4种元素在水稻植株体内的迁移情况.     

黑曲霉As3.4309发酵转化芦丁的研究

目的:利用黑曲霉As3.4309发酵产酶,对芦丁的二元糖苷链进行水解,以得到苷元槲皮素.方法:研究黑曲霉As3.4309的最佳产酶条件,对芦丁进行生物转化;用凝胶层析进行转化产物的分离纯化,核磁共振法鉴定其结构.结果:黑曲霉As3.4309发酵转化芦丁的最佳条件:pH为7.0,碳源为3%稻草粉、2%麸皮,氮源为0.5%硫酸铵、0.5%蛋白胨,KH2PO4 3.0mg/mL,MsSO4·7H2O 0.5mg/mL,FeSO4·7H2O 7.5mgL,MnSO4·H2O 2.5mg/L、ZnSO4 2.0mg/L、CoCl2 3.0mg/L,温度30℃,转速180r/min,接种量10%.主要转化产物经过鉴定为槲皮素.结论:该方法简单方便,有效地实现了芦丁的转化,转化产物槲皮素的转化率达到54.36%.     

Oleg Grigor’evich Kusakin As a Biogeographer

Oleg Grigorevich Kusakin (1930–2001) was one of the greatest specialists in marine biogeography. His contribution was especially significant in the geographical zonation of cold and temperate waters of the Northern and Southern Hemispheres, into the unification of biogeographical terminology and nomenclature of the units of biogeographical zonation, and into the solution of the problem about the age and modes of the origin of the deep-sea fauna in the World Ocean.Original Russian Text Copyright © 2005 by Biologiya Morya, Kafanov.     

Should Bacteriophages Be Classified As Parasites Or Predators?

Bacteriophages are viruses infecting bacteria and propagating in bacterial cells. They were discovered over 100 years ago, and for decades they played crucial roles as models in genetics and molecular biology and as tools in genetic engineering and biotechnology. Now we also recognize their huge role in natural environment and their importance in human health and disease. Despite our understanding of bacteriophage mechanisms of development, these viruses are described as parasites or predators in the literature. From the biological point of view, there are fundamental differences between parasites and predators. Therefore, in this article, I asked whether bacteriophages should be classified as former or latter biological entities. Analysis of the literature and biological definitions led me to conclude that bacteriophages are parasites rather than predators and should be classified and described as such. If even more precise ecological classification is needed, bacteriophages can perhaps be included in the group of parasitoids. It might be the most appropriate formal classification of these viruses, especially if strictly virulent phages are considered, contrary to phages which lysogenize host cells and those which develop according to the permanent infection mode (or chronic cycle, like filamentous phages) revealing features of classical parasites.     

Dihydropyrimidones: As novel class of β-glucuronidase inhibitors

Dihydropyrimidones 1–37 were synthesized via a ‘one-pot’ three component reaction according to well-known Biginelli reaction by utilizing Cu(NO₃)₂·3H₂O as catalyst, and screened for their in vitro β-glucuronidase inhibitory activity. It is worth mentioning that amongst the active molecules, compounds 8 (IC₅₀ = 28.16 ± .056 μM), 9 (IC₅₀ = 18.16 ± 0.41 μM), 10 (IC₅₀ = 22.14 ± 0.43 μM), 13 (IC₅₀ = 34.16 ± 0.65 μM), 14 (IC₅₀ = 17.60 ± 0.35 μM), 15 (IC₅₀ = 15.19 ± 0.30 μM), 16 (IC₅₀ = 27.16 ± 0.48 μM), 17 (IC₅₀ = 48.16 ± 1.06 μM), 22 (IC₅₀ = 40.16 ± 0.85 μM), 23 (IC₅₀ = 44.16 ± 0.86 μM), 24 (IC₅₀ = 47.16 ± 0.92 μM), 25 (IC₅₀ = 18.19 ± 0.34 μM), 26 (IC₅₀ = 33.14 ± 0.68 μM), 27 (IC₅₀ = 44.16 ± 0.94 μM), 28 (IC₅₀ = 24.16 ± 0.50 μM), 29 (IC₅₀ = 34.24 ± 0.47 μM), 31 (IC₅₀ = 14.11 ± 0.21 μM) and 32 (IC₅₀ = 9.38 ± 0.15 μM) found to be more potent than the standard d-saccharic acid 1,4-lactone (IC₅₀ = 48.4 ± 1.25 μM). Molecular docking study was conducted to establish the structure–activity relationship (SAR) which demonstrated that a number of structural features of dihydropyrimidone derivatives were involved to exhibit the inhibitory potential. All compounds were characterized by spectroscopic techniques such as ¹H, ¹³C NMR, EIMS and HREI-MS.     

Addgene: Making Materials Sharing “Science As Usual”

Addgene (www.addgene.org) is a nonprofit organization that facilitates biomedical research and discovery by improving access to useful research materials and information. To fulfill this mission, Addgene works with hundreds of laboratories all over the world to collect high-quality published plasmids and data for the repository that can then be distributed to academic institutions and used to further research. Biological resource centers such as Addgene are an important part of the scientific infrastructure. They play a key role in helping scientists overcome logistical barriers to sharing, improving experimental reproducibility, and optimizing use of limited resources.     

水稻—土壤生态系统对Cu,As污染的缓冲作用

通过对冶炼厂区周围水系、土壤和水稻中Ｃｕ、Ａｓ含量分析,探讨其对农田生态环境的影响。结果表明,各稻田耕作层渗出水和相邻塘水中的Ｃｕ平均浓度分别为０．０５９和０．０７０ｍｇ．Ｌ＾－１,Ａｓ为３１．６８和４２．７９μｇ．Ｌ＾－１,稻田土壤中未出现Ｃｕ、Ａｓ明显的梯度累积变化以及水稻能吸收累积相当数量的Ｃｕ、Ａｓ,它们大部分累积在根部,可以认为,水稻土壤生态系统本身对Ｃｕ、Ａｓ污染具有相当大的缓冲作用。     

香蒲对锑矿渣中Sb和As的富集特征

对贵州某锑矿尾矿库进行野外调查、采样,测试该尾矿库矿渣以及生长在渣场内的香蒲(根、茎、叶)中锑与砷的含量。结果表明:渣中锑和砷平均含量分别为3216.49和27.12 mg·kg-1,香蒲根部锑和砷平均含量分别为617.64和19.87 mg·kg-1,叶中锑和砷含量平均值为183.63和0.41 mg·kg-1,茎中锑平均含量为97.63 mg·kg-1。分析表明,香蒲叶中的Sb含量与茎中Sb含量、渣中As含量与渣中Sb含量具有显著相关性,其余各变量之间相关性均不明显。另外,香蒲对矿渣中锑和砷有较强的耐受性,经估算,香蒲对Sb的年转移量为1278 mg·m-2(地上部分为342.71 mg·m-2,地下部分为935.29 mg·m-2);香蒲对As年转移量为31.46 mg·m-2(地上部分为0.75 mg·m-2,地下部分为30.71mg·m-2)。因此,香蒲可作为Sb矿区,特别是尾矿库Sb和As复合污染区生态修复的目标植物之一。     

DNA甲基化调控炎症反应干预As斑块稳定性的研究进展

动脉粥样硬化(As)斑块破裂是导致急性心脑血管事件发生的首要原因。既往对斑块破裂的基础研究多集中于细胞和分子水平,从表观遗传学角度阐述的研究较少。DNA甲基化作为表观遗传学修饰的主要方式之一,可在不改变基因核苷酸序列的情况下影响基因的表达。综合目前研究来看,炎症反应在斑块破裂过程中起关键性作用,而DNA甲基化对炎症反应又起重要的调控作用。因此,改变DNA甲基化状态来调控炎症反应干预As斑块稳定性,有望成为防治As等心脑血管疾病的有效途径之一。本文主要围绕与As炎症反应密切相关的几种炎症免疫细胞及炎症因子等方面,对近年来DNA甲基化调控炎症反应干预As斑块稳定性的研究进展作一综述。     

水稻－土壤生态系统对Cu、As污染的缓冲作用

通过对冶炼厂区周围水系、土壤和水稻中Ｃｕ、ＡＳ含量分析,探讨其对农田生态环境的影响．结果表明,各稻田耕作层渗出水和相邻塘水中的Ｃｕ平均浓度分别为０．０５９和０．０７ｂｍｇ·Ｌ（－１）,Ａｓ为３１．６８和４２．７９μｇ·Ｌ（－１）,稻田土壤中未出现Ｃｕ、Ａｓ明显的梯度累积变化以及水稻能吸收累积相当数量的Ｃｕ、Ａｓ,它们大部分累积在根部．可以认为,水稻一土壤生态系统本身对Ｃｕ、ＡＳ污染具有相当大的缓冲作用．     

污染作物籽实中As的分布及其结合形态初探

对水稻和小麦籽实中Ａｓ的分布,结合形态及加工去除进行了初步研究,结果表明,Ａｓ在谷物各结构部位中的分布不均,在水稻籽实中浓度分布顺序为胚〉种皮〉颖壳〉胚乳,小麦中Ａｓ的浓度分布顺序为胚〉种皮〉胚乳;Ａｓ在各形态部位的累积量不同,主要存留在胚乳中;Ａｓ主要与蛋白质相结合的形态存在;在稻谷去颖壳、粗米糠和精米糠的过程中,可分别去除Ａｓ１６．５１％、１２．４１％和１０．２６％,小麦也随着加工深度的升级,     

构建一种检测水中As3+的敏感型大肠杆菌

为构建一种敏感性强、特异性好的检测砷离子的大肠杆菌荧光报告菌株,本研究利用基因敲除技术,敲除了大肠杆菌中负责向胞外转运砷离子的ars B基因,构建对As~(3+)敏感的菌株;利用egfp基因作为报告基因,构建融合检测载体p ET28b-Pars-ars R-egfp。然后将检测载体p ET28b-Pars-ars R-egfp转化至ars B基因敲除菌中完成敏感型As~(3+)检测菌株的构建。接着对此微生物传感器进行了检测条件的优化,以及线性检测范围、最低检出限、特异性等性能的确定。研究结果表明,与利用野生大肠杆菌作为检测宿主相比,此敏感型砷检测菌株对检测As~(3+)的灵敏度有显著提高,最适检测As~(3+)浓度范围为0.013-42.71μmol/L,最低检出下限为5.13 nmol/L。因此,本研究利用基因敲除技术对大肠杆菌进行改造,成功地提高了砷检测微生物传感器的灵敏度,为重金属微生物传感器的优化研究工作提供了有用方案。     

双孢蘑菇杂交菌株As2796家系的分子遗传研究

应用PCR和凝胶电泳等技术,对双孢蘑菇杂交菌株As2796及其亲本和子代作分子遗传标记跟踪分析,结果如下: 1) 总DNA的RAPD分析表明,随着遗传代数的增加,杂种子代和出发异核体亲本间的遗传差异逐渐增大; 2) mtDNA的酶切图谱表明,亲本8213及其杂交子代具有相同的基因型,表明双孢蘑菇的mtDNA呈单亲遗传; 3) Est同工酶的PAGE图谱表明, 结合了亲本02高产特征和8213优质特征的杂交子代具有两个亲本的标记带型,证明Est同工酶标记是双孢蘑菇新菌株特性预测或鉴定的有效指标。     

双孢蘑菇杂交菌株As2796家系的分子遗传研究

应用PCR和凝胶电泳等技术,对双孢蘑菇杂交菌株As2796及其亲本和子代作分子遗传标记跟踪分析,结果如下：1）总DNA的RAPD分析表明,随着遗传代数的增加,杂种子代和出发异核体亲本间的遗传差异逐渐增大;2）mtDNA的酶切图谱表明,亲本8213及其杂交子代具有相同的基因型,表明双孢蘑菇mtDNA呈单亲遗传;3）Est同工酶的PAGE图谱表明,结合了亲本02高产特征和8213优质特征的杂交子代具有两个亲本的标记带型,证明Est同工酶标记是双孢蘑菇新菌株特性预测或鉴定的有效指标。