Töne hoher Frequenz bei Mäusen

Summary The bank vole (Evotomys glareolus Schreb.) utters sounds of high frequency which are below or above the upper limit of audibility of man in order to get into contact with companions of the same species. Informative experiments prove thatPreyer's auricle reflex and a further reflex action (a short shrug of the dorsal skin) may equally be induced by sounds above the human limit of audibility Further experiments with an electroacoustic method are in preparation.     

The molecular sociology of the cell

Proteomic studies have yielded detailed lists of the proteins present in a cell. Comparatively little is known, however, about how these proteins interact and are spatially arranged within the 'functional modules' of the cell: that is, the 'molecular sociology' of the cell. This gap is now being bridged by using emerging experimental techniques, such as mass spectrometry of complexes and single-particle cryo-electron microscopy, to complement traditional biochemical and biophysical methods. With the development of integrative computational methods to exploit the data obtained, such hybrid approaches will uncover the molecular architectures, and perhaps even atomic models, of many protein complexes. With these structures in hand, researchers will be poised to use cryo-electron tomography to view protein complexes in action within cells, providing unprecedented insights into protein-interaction networks.     

An integrated semiconductor device enabling non-optical genome sequencing

The seminal importance of DNA sequencing to the life sciences, biotechnology and medicine has driven the search for more scalable and lower-cost solutions. Here we describe a DNA sequencing technology in which scalable, low-cost semiconductor manufacturing techniques are used to make an integrated circuit able to directly perform non-optical DNA sequencing of genomes. Sequence data are obtained by directly sensing the ions produced by template-directed DNA polymerase synthesis using all-natural nucleotides on this massively parallel semiconductor-sensing device or ion chip. The ion chip contains ion-sensitive, field-effect transistor-based sensors in perfect register with 1.2 million wells, which provide confinement and allow parallel, simultaneous detection of independent sequencing reactions. Use of the most widely used technology for constructing integrated circuits, the complementary metal-oxide semiconductor (CMOS) process, allows for low-cost, large-scale production and scaling of the device to higher densities and larger array sizes. We show the performance of the system by sequencing three bacterial genomes, its robustness and scalability by producing ion chips with up to 10 times as many sensors and sequencing a human genome.     

The knockout mouse project

Mouse knockout technology provides a powerful means of elucidating gene function in vivo, and a publicly available genome-wide collection of mouse knockouts would be significantly enabling for biomedical discovery. To date, published knockouts exist for only about 10% of mouse genes. Furthermore, many of these are limited in utility because they have not been made or phenotyped in standardized ways, and many are not freely available to researchers. It is time to harness new technologies and efficiencies of production to mount a high-throughput international effort to produce and phenotype knockouts for all mouse genes, and place these resources into the public domain.     

A critical role for the protein tyrosine phosphatase receptor type Z in functional recovery from demyelinating lesions

Several lines of evidence suggest that tyrosine phosphorylation is a key element in myelin formation, differentiation of oligodendrocytes and Schwann cells, and recovery from demyelinating lesions. Multiple sclerosis is a demyelinating disease of the human central nervous system, and studies of experimental demyelination indicate that remyelination in vivo requires the local generation, migration or maturation of new oligodendrocytes, or some combination of these. Failure of remyelination in multiple sclerosis could result from the failure of any of these processes or from the death of oligodendrocytes. Ptprz encodes protein tyrosine phosphatase receptor type Z (Ptpz, also designated Rptpbeta), which is expressed primarily in the nervous system but also in oligodendrocytes, astrocytes and neurons. Here we examine the susceptibility of mice deficient in Ptprz to experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis. We observe that mice deficient in Ptprz show impaired recovery from EAE induced by myelin oligodendrocyte glycoprotein (MOG) peptide. This sustained paralysis is associated with increased apoptosis of mature oligodendrocytes in the spinal cords of mutant mice at the peak of inflammation. We further demonstrate that expression of PTPRZ1, the human homolog of Ptprz, is induced in multiple sclerosis lesions and that the gene is specifically expressed in remyelinating oligodendrocytes in these lesions. These results support a role for Ptprz in oligodendrocyte survival and in recovery from demyelinating disease.     

The human TAS2R16 receptor mediates bitter taste in response to beta-glucopyranosides

Bitter taste generally causes aversion, which protects humans from ingesting toxic substances. But bitter flavors also contribute to the palatability of food and beverages, thereby influencing nutritional habits in humans. Although many studies have examined bitter taste, the underlying receptor mechanisms remain poorly understood. Anatomical, functional and genetic data from rodents suggest the existence of a family of receptors that are responsive to bitter compounds. Here we report that a human member of this family, TAS2R16, is present in taste receptor cells on the tongue and is activated by bitter beta-glucopyranosides. Responses to these phytonutrients show a similar concentration dependence and desensitization in transfected cells and in experiments assessing taste perception in humans. Bitter compounds consisting of a hydrophobic residue attached to glucose by a beta-glycosidic bond activate TAS2R16. Thus, TAS2R16 links the recognition of a specific chemical structure to the perception of bitter taste. If the ability of TAS2R16 to detect substances with common molecular properties is typical of the bitter receptor family, it may explain how a few receptors permit the perception of numerous bitter substances.     

Bose-Einstein condensation of atomic gases

The early experiments on Bose-Einstein condensation in dilute atomic gases accomplished three long-standing goals. First, cooling of neutral atoms into their motional ground state, thus subjecting them to ultimate control, limited only by Heisenberg's uncertainty relation. Second, creation of a coherent sample of atoms, in which all occupy the same quantum state, and the realization of atom lasers - devices that output coherent matter waves. And third, creation of a gaseous quantum fluid, with properties that are different from the quantum liquids helium-3 and helium-4. The field of Bose-Einstein condensation of atomic gases has continued to progress rapidly, driven by the combination of new experimental techniques and theoretical advances. The family of quantum-degenerate gases has grown, and now includes metastable and fermionic atoms. Condensates have become an ultralow-temperature laboratory for atom optics, collisional physics and many-body physics, encompassing phonons, superfluidity, quantized vortices, Josephson junctions and quantum phase transitions.     

Selective imprinting of gut-homing T cells by Peyer's patch dendritic cells

Whereas naive T cells migrate only to secondary lymphoid organs, activation by antigen confers to T cells the ability to home to non-lymphoid sites. Activated effector/memory T cells migrate preferentially to tissues that are connected to the secondary lymphoid organs where antigen was first encountered. Thus, oral antigens induce effector/memory cells that express essential receptors for intestinal homing, namely the integrin alpha4beta7 and CCR9, the receptor for the gut-associated chemokine TECK/CCL25 (refs 6, 8, 9). Here we show that this imprinting of gut tropism is mediated by dendritic cells from Peyer's patches. Stimulation of CD8-expressing T cells by dendritic cells from Peyer's patches, peripheral lymph nodes and spleen induced equivalent activation markers and effector activity in T cells, but only Peyer's patch dendritic cells induced high levels of alpha4beta7, responsiveness to TECK and the ability to home to the small intestine. These findings establish that Peyer's patch dendritic cells imprint gut-homing specificity on T cells, and thus license effector/memory cells to access anatomical sites most likely to contain their cognate antigen.     

“三极对垒”还是“四分天下”——中国在全球科技中的新角色

美国与欧盟争夺世界科技领先者的竞赛是当前研究的热点。欧洲委员会最近的研究表明,欧洲在世界科技产出中所占的比重日益增加,并宣布欧洲上世纪末处于科学产出的领先地位。为了对全球发展态势进行监测,该研究对1991-2005年共15年的数据进行了分析。对科技产出活动和影响模式的分析采用的是一套文献计量指标和技术计量指标,这套指标包括:(1)出版物产出指标,如占世界总量的份额和基于主题的出版物分布概况;(2)引文指标,如基于期刊和基于主题的归一化平均引用率;(3)国际合作论文及其影响;(4)专利指标以及专利与论文之间的相互引用关系。同时文章还讨论了国家层面的文献计量学特征的演变、"科学权重"以及科学技术关联的模式。研究结果表明,采用科学技术指标这面镜子所反映的"三极对垒"模式在21世纪将不会长久,中国正在挑战一流科学经济强国的地位,并且其成为世界第二大科技强国的时代正在到来。