CFL2基因研究进展

CFL2(Cofilin2)基因是肌动蛋白结合蛋白cofilin家族的新成员,主要在哺乳动物的骨骼肌和心肌表达,被认为是肌肉组织肌动蛋白装配的调节器,对正常肌肉功能和肌肉再生起着重要的作用。目前未见对CFL2基因进行全面介绍的文章,因此拟对CFL2基因的表达、结构、蛋白功能及其与肌病相关性方面的研究进展作一综述。     

Biogeochemistry. Sulfate reducers--dominant players in a low-oxygen world?

Sulfate reducing bacteria can adapt to extreme physical and chemical conditions and play an important role in global geochemical cycles, but their role in the formation of ore deposits has remained controversial. Strong support for such a role is provided by Labrenz et al., who have discovered sulfate-reducing bacteria that can tolerate low levels of oxygen and can precipitate zinc sulfide minerals. The results may have implications for bioremediation and may provide clues to processes that may have been more widespread in the geologic past.     

一种扩展角色访问控制模型的研究与实现

针对传统的角色访问控制(RBAC)模型的不足,对角色权限及角色层次关系进行了分析,提出了一个改进的角色访问控制模型——ERBAC。应用实例说明,新模型在描述同样的角色关系时角色数量比传统模型要少,因而比传统模型更加简化和直观,特别适合于管理信息系统的应用。     

Human IRGM induces autophagy to eliminate intracellular mycobacteria

Immunity-related p47 guanosine triphosphatases (IRG) play a role in defense against intracellular pathogens. We found that the murine Irgm1 (LRG-47) guanosine triphosphatase induced autophagy and generated large autolysosomal organelles as a mechanism for the elimination of intracellular Mycobacterium tuberculosis. We also identified a function for a human IRG protein in the control of intracellular pathogens and report that the human Irgm1 ortholog, IRGM, plays a role in autophagy and in the reduction of intracellular bacillary load.     

一种扩展角色访问控制模型的研究与实现

针对传统的角色访问控制(RBAC)模型的不足,对角色权限及角色层次关系进行了分析,提出了一个改进的角色访问控制模型——ERBAC。应用实例说明,新模型在描述同样的角色关系时角色数量比传统模型要少,因而比传统模型更加简化和直观,特别适合于管理信息系统的应用。     

观赏草的研究与应用

探讨了观赏草的研究和应用现状,结果显示观赏草在节约型园林建设中具有重要的作用,观赏草将在我国园林植物应用中占据一席之地。     

乡村振兴中发挥农民主体作用的路径探析

乡村振兴中发挥农民主体作用符合乡村振兴战略的人本旨归，是落实乡村振兴战略的关键，也是保障乡村振兴战略取得实效的必要手段。当前，农民自身能力素质不足、组织化程度偏低以及社会对农民的保障机制不完善等因素制约了农民主体作用的发挥。未来要强化宣传教育培训、打造乡村共同体、完善制度体系、建立健全长效机制，充分发挥农民主体作用，稳步推进乡村振兴。     

Neuroscience. Immune molecules prune neural links

In work described on page 2155, a team of neuroscientists suggests that the class I major histocompatibility complex proteins, previously known for their role in controlling immune responses, also play a role in the nervous system. They are necessary for the formation of normal neuronal connections in a visual area of the brain during development, and later in life, they're called into play in the hippocampus, a brain area involved in memory and learning. The work shows a completely unexpected function for the immune system molecules.     

Extracellular DNA plays a key role in deep-sea ecosystem functioning

The ecological role and biogeochemical relevance of extracellular DNA in the oceanic sediments are unknown. Our global estimates indicate that up to 0.45 gigatons of extracellular DNA are present in the top 10 centimeters of deep-sea sediments, representing the largest reservoir of DNA in the world oceans. We demonstrate that extracellular DNA accounts for about one fifth of the total organic phosphorus regeneration and provides almost half of the prokaryotic demand for organic phosphorus. It therefore plays a key role in deep-sea ecosystem functioning on a global scale.     

Cell Lysis: Another Function of the Coat Protein of the Bacteriophage f2

Evidence is presented that the coat protein of bacteriophage f2 causes the lysis of infected Escherichia coli. To lyse bacteria, the coat protein produced must be of the quality to produce phage particles, although it need not be produced in amounts sufficient to give a large yield of particles. Mutants that are blocked in coat-protein synthesis, or that direct the synthesis of an imperfect coat protein, do not lyse their host bacteria. In addition to its obvious structural role and its postulated regulatory role, another, perhaps enzymatic, role has been found for the coat protein of the phage f2.     

ASTRONOMY: Enhanced: Monsters at the Heart of Galaxy Formation

Supermassive black holes (BHs) have long been implicated in explaining active galactic nuclei such as quasars. In his Perspective, Kormendy discusses recent work that suggests a larger role for these objects. The Hubble Space Telescope has provided many new detections of BHs, and these new results indicate that they play an important role in the galaxy formation processes.     

农科学生英语课堂上的母语依赖分析

从教育心理学和二语习得学科的角度,结合问卷调查,分析农科学生在英语课堂上母语依赖的客观存在性及其发挥的作用。研究表明,农科学生在英语课堂上的母语依赖是客观存在的,母语依赖发挥着缓解学习者心理焦虑,提高学习动机和增强对比意识等作用。     

Regulation of spontaneous intestinal tumorigenesis through the adaptor protein MyD88

Inflammation is increasingly recognized as an important component of tumorigenesis, although the mechanisms and pathways involved are not well understood. Tumor development is regulated by products of several modifier genes, but instructions for their tumor-specific expression are currently unknown. We show that the signaling through the adaptor protein MyD88 has a critical role in spontaneous tumor development in mice with heterozygous mutation in the adenomatous polyposis coli (APC) gene. We found that MyD88-dependent signaling controls the expression of several key modifier genes of intestinal tumorigenesis and has a critical role in both spontaneous and carcinogen-induced tumor development. This study thus reveals the important role of an innate immune signaling pathway in intestinal tumorigenesis.     

鸟类与植物种子扩散关系的研究进展

种子扩散是指种子以某种方式离开母树到达适宜生境并能生长、繁殖,实现定居的过程。种子靠不同的方式实现扩散,如通过动物、风、水和自我扩散。其中,在动物扩散类群中,鸟类是最重要的扩散者。国外学者对鸟类在植物种子扩散中的作用、鸟类对种子的扩散距离、鸟类摄食对种子萌发的影响以及食果鸟类与结果植物之间的关系等问题进行了大量研究,为进一步探讨鸟类与植物种子扩散的关系提供了理论基础。鸟类对植物种子的扩散既有积极的作用,也能产生不利的影响。近年来,越来越多的学者关注鸟类在森林更新中的作用,并呼吁应更好地发挥鸟类在植物种子扩散中的积极作用。国内对鸟类扩散的研究起步较晚,但近年来已有越来越多的学者开始关注鸟类与植物之间的关系,并对鸟类在传播红松、红豆杉、黄檗等植物种子的作用进行了研究。     

Essential roles for ecdysone signaling during Drosophila mid-embryonic development

Although functions for the steroid hormone ecdysone during Drosophila metamorphosis have been well established, roles for the embryonic ecdysone pulse remain poorly understood. We show that the EcR-USP ecdysone receptor is first activated in the extraembryonic amnioserosa, implicating this tissue as a source of active ecdysteroids in the early embryo. Ecdysone signaling is required for germ band retraction and head involution, morphogenetic movements that shape the first instar larva. This mechanism for coordinating morphogenesis during Drosophila embryonic development parallels the role of ecdysone during metamorphosis. It also provides an intriguing parallel with the role of mammalian extraembryonic tissues as a critical source of steroid hormones during embryonic development.     

谷氨酰胺合成酶及其在植物基因工程中应用研究进展

植物谷氨酰胺合成酶不仅是植物氨同化的关键酶,也是影响植物抗逆性及作物产量的重要因素之一.文章对植物谷氨酰胺合成酶的种类、结构、基因、基因表达及其在植物基因工程中的应用进行综述,认为植物对不同氮源吸收及运输的机制、谷氨酰胺合成酶等关键酶不同异构体在植物生长繁育涉及的生理反应中的作用及其调节机制、谷氨酰胺合成酶在利用雄性不育进行杂交育种中可能的应用等仍待进一步研究.     

植物根围促生细菌（PGPR）的分离筛选及对黄瓜土传病害的防治

为获取防治黄瓜土传病害的植物根围促生菌(PGPR)并明确其防效,采用促生筛选法与大田小区试验法,对黄瓜根围的促生细菌进行了筛选并对其田间防效进行了研究。结果表明,通过盆栽测定结合平皿初筛,筛选到的三株PGPR菌株,CH1,CH2和CH3都能显著地促进黄瓜生长。此外,离体拮抗试验发现,CH1和CH2对黄瓜枯萎病菌都有拮抗作用,而对瓜果腐霉均无拮抗作用,CH3对两种病原菌都有拮抗作用。盆栽防病效果测定,证实了这三株PGPR对黄瓜枯萎病和猝倒病都有较好的防治效果,田间试验进一步验证了其防效,并且发现PGPR间的亲和与非亲和性组合的促生与防病效果都显著好于单株的。这些试验结果为三株PGPRs的进一步研究和产业化奠定了坚实的基础。     

An active role for tRNA in decoding beyond codon:anticodon pairing

During transfer RNA (tRNA) selection, a cognate codon:anticodon interaction triggers a series of events that ultimately results in the acceptance of that tRNA into the ribosome for peptide-bond formation. High-fidelity discrimination between the cognate tRNA and near- and noncognate ones depends both on their differential dissociation rates from the ribosome and on specific acceleration of forward rate constants by cognate species. Here we show that a mutant tRNA(Trp) carrying a single substitution in its D-arm achieves elevated levels of miscoding by accelerating these forward rate constants independent of codon:anticodon pairing in the decoding center. These data provide evidence for a direct role for tRNA in signaling its own acceptance during decoding and support its fundamental role during the evolution of protein synthesis.     

Ant nestmate and non-nestmate discrimination by a chemosensory sensillum

In animal societies, chemical communication plays an important role in conflict and cooperation. For ants, cuticular hydrocarbon (CHC) blends produced by non-nestmates elicit overt aggression. We describe a sensory sensillum on the antennae of the carpenter ant Camponotus japonicus that functions in nestmate discrimination. This sensillum is multiporous and responds only to non-nestmate CHC blends. This suggests a role for a peripheral recognition mechanism in detecting colony-specific chemical signals.