Temperature and manganese as determining factors in the presence of diatom or blue-green algal floras in streams.

abstract：:Questions that still surround the origin and early dispersals of maize (Zea mays L.) result in large part from the absence of information on its early history from the Balsas River Valley of tropical southwestern Mexico, where its wild ancestor is native. We report starch grain and phytolith data from the Xihuatoxtla ...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Piperno DR,Ranere AJ,Holst I,Iriarte J,Dickau R

更新日期：2009-03-31 00:00:00

abstract：:Single-molecule methods have given experimental access to the mechanical properties of single protein molecules. So far, access has been limited to mostly one spatial direction of force application. Here, we report single-molecule experiments that explore the mechanical properties of a folded protein structure in prec...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Dietz H,Berkemeier F,Bertz M,Rief M

更新日期：2006-08-22 00:00:00

abstract：:The histidine periplasmic permease of Salmonella typhimurium has been partially purified and reconstituted into proteoliposomes. In this in vitro preparation, transport activity is completely dependent on the presence of all four permease proteins (HisJ, HisQ, HisM, and HisP) and on internal ATP. The reconstituted sys...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Bishop L,Agbayani R Jr,Ambudkar SV,Maloney PC,Ames GF

更新日期：1989-09-01 00:00:00

abstract：:Type II platelet-activating factor-acetylhydrolase [PAF-AH (II)] is an N-myristoylated enzyme that contains a lipase/esterase catalytic motif and selectively hydrolyzes the sn-2 acetyl ester of PAF and other short-chain acyl groups attached to phosphoglycerides. However, the physiological role of this enzyme remains t...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Inoue T,Sugimoto A,Suzuki Y,Yamamoto M,Tsujimoto M,Inoue K,Aoki J,Arai H

更新日期：2004-09-07 00:00:00

abstract：:The complete amino acid sequence of Xenopus laevis nonmuscle myosin heavy chain B (MHC-B) has been deduced from overlapping cDNA clones isolated from an XTC cell library. RNA blots of various developmental stages, adult tissues, and XTC cells detect a single transcript of 7.5 kb which is expressed at similar levels th...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Bhatia-Dey N,Adelstein RS,Dawid IB

更新日期：1993-04-01 00:00:00

abstract：:Malaria infection triggers vigorous host immune responses; however, the parasite ligands, host receptors, and the signaling pathways responsible for these reactions remain unknown or controversial. Malaria parasites primarily reside within RBCs, thereby hiding themselves from direct contact and recognition by host imm...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Wu J,Tian L,Yu X,Pattaradilokrat S,Li J,Wang M,Yu W,Qi Y,Zeituni AE,Nair SC,Crampton SP,Orandle MS,Bolland SM,Qi CF,Long CA,Myers TG,Coligan JE,Wang R,Su XZ

更新日期：2014-01-28 00:00:00

abstract：:The S100A8/S100A9 heterodimer calprotectin (CP) functions in the host response to pathogens through a mechanism termed "nutritional immunity." CP binds Mn(2+) and Zn(2+) with high affinity and starves bacteria of these essential nutrients. Combining biophysical, structural, and microbiological analysis, we identified ...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Damo SM,Kehl-Fie TE,Sugitani N,Holt ME,Rathi S,Murphy WJ,Zhang Y,Betz C,Hench L,Fritz G,Skaar EP,Chazin WJ

更新日期：2013-03-05 00:00:00

abstract：:In human adults, learning and memory under acute stress are characterized by an increased use of rigid habitual response strategies at the cost of flexible cognitive strategies. The immediate effects of stress on cognitive functioning early in life are not well understood. Here we show experimentally that acute stress...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Seehagen S,Schneider S,Rudolph J,Ernst S,Zmyj N

更新日期：2015-10-13 00:00:00

abstract：:We have identified an adenovirus type 5(Ad5) early gene function located in early region 1 which is required for the production of early cytoplasmic mRNAs corresponding to early regions 2, 3, and 4. Mutant dl312 (lacks the segment between 1.5 and 4.5 map units) grows as well as wild-type virus in 293 cells (Ad5-trans...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Jones N,Shenk T

更新日期：1979-08-01 00:00:00

abstract：:Synaptic transmission depends on the continued availability of neurotransmitter-filled synaptic vesicles (SVs) for triggered release from presynaptic boutons. Surprisingly, small boutons in the brain, that already contain comparatively few SVs, are thought to retain the majority of these SVs in a "reserve" pool that i...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Ikeda K,Bekkers JM

更新日期：2009-02-24 00:00:00

abstract：:The crystal structure of the decapeptide Boc-Aib-Glu(OBzl)-Leu-Aib-Ala-Leu-Aib-Ala-Lys(Z)-Aib-OMe (where Aib is alpha-aminoisobutyryl, Boc is t-butoxycarbonyl, OBzl is benzyl ester, and Z is benzyloxycarbonyl) illustrates a parallel zipper arrangement of interacting helical peptide columns. Head-to-tail NH...OC hydrog...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Karle IL,Flippen-Anderson JL,Uma K,Balaram P

更新日期：1990-10-01 00:00:00

abstract：:Annual reproductive success and senescence patterns vary substantially among individuals in the wild. However, it is still seldom considered that senescence may not only affect an individual but also affect age-specific reproductive success in its offspring, generating transgenerational reproductive senescence. We use...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Kroeger SB,Blumstein DT,Armitage KB,Reid JM,Martin JGA

更新日期：2020-03-03 00:00:00

abstract：:Solid-state cross-polarization/magic-angle sample-spinning (13)C NMR spectra have been recorded on chlorophyll a-water aggregates, methyl pyrochlorophyllide a, and methyl pyropheophorbide a (derivatives that lack a phytyl chain). Spectra have also been collected under a decoupling regime in which resonances of certain...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Brown CE,Spencer RB,Burger VT,Katz JJ

更新日期：1984-01-01 00:00:00

abstract：:The Drosophila clock genes period (per) and timeless (tim) have been studied behaviorally and biochemically, but to date there has been no viable culture system for studying the cell biology of the Drosophila clock. We have cultured pupal ring glands attached to the central nervous system and observed rhythms of perio...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Emery IF,Noveral JM,Jamison CF,Siwicki KK

更新日期：1997-04-15 00:00:00

abstract：:Bovine adrenal medullary cells, cultured on quartz plates, were superfused with buffer to which pulses of stimulant were added. Cytosolic Ca2+ was measured by the fura-2 fluorescence method and the simultaneously released catecholamine was measured electrochemically. When stimulant concentrations were adjusted to give...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Kim KT,Westhead EW

更新日期：1989-12-01 00:00:00

abstract：:Efforts are underway to construct several recoded genomes anticipated to exhibit multivirus resistance, enhanced nonstandard amino acid (nsAA) incorporation, and capability for synthetic biocontainment. Although our laboratory pioneered the first genomically recoded organism (Escherichia coli strain C321.∆A), its fitn...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Wannier TM,Kunjapur AM,Rice DP,McDonald MJ,Desai MM,Church GM

更新日期：2018-03-20 00:00:00

abstract：:Inhomogeneous ab initio molecular dynamics simulations show that vaporization of MgSiO3 is incongruent and that the vapor phase is dominated by SiO and O2 molecules. The vapor is strongly depleted in Mg at low temperature and approaches the composition of the liquid near the critical point. We find that the liquid-vap...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Xiao B,Stixrude L

更新日期：2018-05-22 00:00:00

abstract：:Transthyretin (TTR) is a globular tetrameric transport protein in plasma. Nearly 140 single amino acid substitutions in TTR cause life-threatening amyloid disease. We report a one-of-a-kind pathological variant featuring a Glu51, Ser52 duplication mutation (Glu51_Ser52dup). The proband, heterozygous for the mutation, ...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Klimtchuk ES,Prokaeva T,Frame NM,Abdullahi HA,Spencer B,Dasari S,Cui H,Berk JL,Kurtin PJ,Connors LH,Gursky O

更新日期：2018-07-10 00:00:00

abstract：:Transcriptional activation of the HIV type 1 (HIV-1) long terminal repeat (LTR) promoter element by the viral Tat protein is an essential step in the HIV-1 life cycle. Tat function is mediated by the TAR RNA target element encoded within the LTR and is known to require the recruitment of a complex consisting of Tat an...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Bieniasz PD,Grdina TA,Bogerd HP,Cullen BR

更新日期：1999-07-06 00:00:00

abstract：:Insects, as a group, have been remarkably successful in adapting to a great range of physical and biological environments, in large part because of their ability to fly. The evolution of flight in small insects was accompanied by striking adaptations of the thoracic musculature that enabled very high wing beat frequen...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Swank DM,Vishnudas VK,Maughan DW

更新日期：2006-11-14 00:00:00

abstract：:Purified influenza viral cores catalyze the entire process of viral RNA transcription, which includes the endonucleolytic cleavage of heterologous RNAs containing cap 1 (m(7)GpppNm) structures to generate capped primers 10-13 nucleotides long, the initiation of transcription via the incorporation of a guanosine residu...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Ulmanen I,Broni BA,Krug RM

更新日期：1981-12-01 00:00:00

abstract：:The effect of phagocytosis on lectin binding to plasma membranes of polymorphonuclear leukocytes was examined. The specific activities of binding sites of concanavalin A and Ricinus communis agglutinin (defined as mug of lectin bound per 100 mug of membrane protein) were measured on isolated membranes; they decreased ...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Oliver JM,Ukena TE,Berlin RD

更新日期：1974-02-01 00:00:00

abstract：:The spontaneous assembly of proteins into amyloid fibrils is a phenomenon central to many increasingly common and currently incurable human disorders, including Alzheimer's and Parkinson's diseases. Oligomeric species form transiently during this process and not only act as essential intermediates in the assembly of n...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Dear AJ,Michaels TCT,Meisl G,Klenerman D,Wu S,Perrett S,Linse S,Dobson CM,Knowles TPJ

更新日期：2020-06-02 00:00:00

abstract：:The mammalian AML/CBFalpha runt domain (RD) transcription factors regulate hematopoiesis and osteoblast differentiation. Like their Drosophila counterparts, most mammalian RD proteins terminate in a common pentapeptide, VWRPY, which serves to recruit the corepressor Groucho (Gro). Using a yeast two-hybrid assay, in vi...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Levanon D,Goldstein RE,Bernstein Y,Tang H,Goldenberg D,Stifani S,Paroush Z,Groner Y

更新日期：1998-09-29 00:00:00

abstract：:A joint analysis of all-atom molecular dynamics (MD) calculations and picosecond time-resolved x-ray structures was performed to gain single-molecule insights into mechanisms of protein function. Ensemble-averaged MD simulations of the L29F mutant of myoglobin after ligand dissociation reproduce the direction, amplitu...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Hummer G,Schotte F,Anfinrud PA

更新日期：2004-10-26 00:00:00

abstract：:HIV type 1 (HIV-1) uses the chemokine receptors CCR5 and CXCR4 as coreceptors for entry into target cells. Here we show that the HIV-1 envelope gp120 (Env) activates multiple ionic signaling responses in primary human macrophages, which are important targets for HIV-1 in vivo. Env from both CCR5-dependent JRFL (R5) an...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Liu QH,Williams DA,McManus C,Baribaud F,Doms RW,Schols D,De Clercq E,Kotlikoff MI,Collman RG,Freedman BD

更新日期：2000-04-25 00:00:00

abstract：:The utilization of the isoaccepting species of leucyl-tRNA in protein synthesis has been examined in E. coli. Two minor leucyl-tRNA species, isoacceptors tRNA3Leu and tRNA4Leu, are the predominant species found bound to ribosomes during exponential growth in minimal medium. In rich medium, an increased proportion of t...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Holmes WM,Goldman E,Miner TA,Hatfield GW

更新日期：1977-04-01 00:00:00

abstract：:Unit electrical activity was recorded from single neurons in the isolated lumbo-sacral spinal cord of 14- to 19-day chick embryos, in situ. Spinal cord transection was combined with transection of all lumbo-sacral dorsal roots. The spontaneous discharge of cells is confined, for the most part, to the lower two thirds ...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Sharma SC,Provine RR,Hamburger V,Sandel TT

更新日期：1970-05-01 00:00:00

abstract：:Ancient societies are often used to illustrate the potential problems stemming from unsustainable land-use practices because the past seems rife with examples of sociopolitical "collapse" associated with the exhaustion of finite resources. Just as frequently, and typically in response to such presentations, archaeolog...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Wills WH,Drake BL,Dorshow WB

更新日期：2014-08-12 00:00:00

abstract：:How did language evolve? A popular approach points to the similarities between the ontogeny and phylogeny of language. Young children's language and nonhuman primates' signing both appear formulaic with limited syntactic combinations, thereby suggesting a degree of continuity in their cognitive abilities. To evaluate ...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Yang C

更新日期：2013-04-16 00:00:00