Asynchronous climate changes in the North Atlantic and Japan during the last termination     

Nakagawa T  Kitagawa H  Yasuda Y  Tarasov PE  Nishida K  Gotanda K  Sawai Y;Yangtze River Civilization Program Members 《Science (New York, N.Y.)》2003,299(5607):688-691

Pollen records from the annually laminated sediment sequence in Lake Suigetsu, Japan, suggest a sequence of climate changes during the Last Termination that resembles that of the North Atlantic region but with noticeable differences in timing. An interstadial interval commenced a few centuries earlier [approximately 15,000 years before the present (yr B.P.)] than the North Atlantic GI-1 (B?lling) event. Conversely, the onset of a Younger Dryas (YD)-like cold reversal (12,300 to 11,250 yr B.P.) postdated the North Atlantic GS-1 (YD) event by a few centuries. Climate in the Far East during the Last Termination reflected solar insolation changes as much as Atlantic influences.  相似文献   

Magnetic field-tuned quantum criticality in the metallic ruthenate Sr3Ru2O7     

Grigera SA  Perry RS  Schofield AJ  Chiao M  Julian SR  Lonzarich GG  Ikeda SI  Maeno Y  Millis AJ  Mackenzie AP 《Science (New York, N.Y.)》2001,294(5541):329-332

The concept of quantum criticality is proving to be central to attempts to understand the physics of strongly correlated electrons. Here, we argue that observations on the itinerant metamagnet Sr3Ru2O7 represent good evidence for a new class of quantum critical point, arising when the critical end point terminating a line of first-order transitions is depressed toward zero temperature. This is of interest both in its own right and because of the convenience of having a quantum critical point for which the tuning parameter is the magnetic field. The relationship between the resultant critical fluctuations and novel behavior very near the critical field is discussed.  相似文献   

Chemistry. Nuclear spin conversion in molecules     

Hougen JT  Oka T 《Science (New York, N.Y.)》2005,310(5756):1913-1914

  相似文献   

Distinct kinetic changes in neurotransmitter release after SNARE protein cleavage     

Sakaba T  Stein A  Jahn R  Neher E 《Science (New York, N.Y.)》2005,309(5733):491-494

Neurotransmitter release is triggered by calcium ions and depends critically on the correct function of three types of SNARE [soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptor] proteins. With use of the large calyx of Held presynaptic terminal from rats, we found that cleavage of different SNARE proteins by clostridial neurotoxins caused distinct kinetic changes in neurotransmitter release. When elevating calcium ion concentration directly at the presynaptic terminal with the use of caged calcium, cleavage of SNAP-25 by botulinum toxin A (BoNT/A) produced a strong reduction in the calcium sensitivity for release, whereas cleavage of syntaxin using BoNT/C1 and synaptobrevin using tetanus toxin (TeNT) produced an all-or-nothing block without changing the kinetics of remaining vesicles. When stimulating release by calcium influx through channels, a difference between BoNT/C1 and TeNT emerged, which suggests that cleavage of synaptobrevin modifies the coupling between channels and release-competent vesicles.  相似文献   

Heterochromatin and RNAi are required to establish CENP-A chromatin at centromeres     

Folco HD  Pidoux AL  Urano T  Allshire RC 《Science (New York, N.Y.)》2008,319(5859):94-97

  相似文献   

Mass spectrometry of intact V-type ATPases reveals bound lipids and the effects of nucleotide binding     

Zhou M  Morgner N  Barrera NP  Politis A  Isaacson SC  Matak-Vinković D  Murata T  Bernal RA  Stock D  Robinson CV 《Science (New York, N.Y.)》2011,334(6054):380-385

The ability of electrospray to propel large viruses into a mass spectrometer is established and is rationalized by analogy to the atmospheric transmission of the common cold. Much less clear is the fate of membrane-embedded molecular machines in the gas phase. Here we show that rotary adenosine triphosphatases (ATPases)/synthases from Thermus thermophilus and Enterococcus hirae can be maintained intact with membrane and soluble subunit interactions preserved in vacuum. Mass spectra reveal subunit stoichiometries and the identity of tightly bound lipids within the membrane rotors. Moreover, subcomplexes formed in solution and gas phases reveal the regulatory effects of nucleotide binding on both ATP hydrolysis and proton translocation. Consequently, we can link specific lipid and nucleotide binding with distinct regulatory roles.  相似文献   

Ouabain and streptomycin: their different loci of action on saccular hair cells in goldfish     

S Matsuura  K Ikeda  T Furukawa 《Science (New York, N.Y.)》1968,160(832):1117-1119

Ouabain, when applied to the periotic spaces, that is, to the basal end of the saccular hair cells, suppressed microphonic potentials of the inner ear in goldfish. In contrast, streptomycin produced such an effect only when it was applied directly into the endolymph, that is, to the hair-bearing ends of the hair cells.  相似文献   

Structure of the rotor of the V-Type Na+-ATPase from Enterococcus hirae     

Murata T  Yamato I  Kakinuma Y  Leslie AG  Walker JE 《Science (New York, N.Y.)》2005,308(5722):654-659

The membrane rotor ring from the vacuolar-type (V-type) sodium ion-pumping adenosine triphosphatase (Na+-ATPase) from Enterococcus hirae consists of 10 NtpK subunits, which are homologs of the 16-kilodalton and 8-kilodalton proteolipids found in other V-ATPases and in F1Fo- or F-ATPases, respectively. Each NtpK subunit has four transmembrane alpha helices, with a sodium ion bound between helices 2 and 4 at a site buried deeply in the membrane that includes the essential residue glutamate-139. This site is probably connected to the membrane surface by two half-channels in subunit NtpI, against which the ring rotates. Symmetry mismatch between the rotor and catalytic domains appears to be an intrinsic feature of both V- and F-ATPases.  相似文献   

Use of CD134 as a primary receptor by the feline immunodeficiency virus     

Shimojima M  Miyazawa T  Ikeda Y  McMonagle EL  Haining H  Akashi H  Takeuchi Y  Hosie MJ  Willett BJ 《Science (New York, N.Y.)》2004,303(5661):1192-1195

Feline immunodeficiency virus (FIV) induces a disease similar to acquired immunodeficiency syndrome (AIDS) in cats, yet in contrast to human immunodeficiency virus (HIV), CD4 is not the viral receptor. We identified a primary receptor for FIV as CD134 (OX40), a T cell activation antigen and costimulatory molecule. CD134 expression promotes viral binding and renders cells permissive for viral entry, productive infection, and syncytium formation. Infection is CXCR4-dependent, analogous to infection with X4 strains of HIV. Thus, despite the evolutionary divergence of the feline and human lentiviruses, both viruses use receptors that target the virus to a subset of cells that are pivotal to the acquired immune response.  相似文献   

Quantitative nested real-time PCR detection of <Emphasis Type="Italic">Verticillium longisporum</Emphasis> and <Emphasis Type="Italic">V. dahliae</Emphasis> in the soil of cabbage fields     

Shinpei Banno  Hidenari Saito  Hiroshi Sakai  Toshihiko Urushibara  Kentaro Ikeda  Takeshi Kabe  Isao Kemmochi  Makoto Fujimura 《Journal of General Plant Pathology》2011,77(5):282-291

Verticillium longisporum and V. dahliae, causal agents of Verticillium wilt, are spreading through the cabbage fields of Gunma Prefecture. Using the V. longisporum-specific intron within the 18S rDNA and differences between ITS 5.8S rDNA sequences in Japanese isolates of V. longisporum and V. dahliae, we developed three quantitative nested real-time (QNRT) PCR assays. The QNRT-PCR quantification of V. longisporum or V. dahliae in cabbage field soil was consistent with the severity of Verticillium wilt disease in those fields. In field trials of resistant cultivar YR Ranpo grown for three seasons in soil infested with the pathogen, disease severity and pathogen density in the soil were significantly reduced in a field moderately contaminated by V. dahliae, but only slightly reduced in a highly contaminated field. These results suggest that continuous cultivation of a resistant cultivar is an effective way to reduce the pathogen population. QNRT-PCR assays provide a powerful analytical tool to evaluate the soil population dynamics of V. longisporum and V. dahliae for disease management.  相似文献