Small-scale urban agriculture results in high yields but requires judicious management of inputs to achieve sustainability.

abstract：:Thermotaxis by individual amoebae of Dictyostelium discoideum on a temperature gradient is described. These amoebae show positive thermotaxis at temperatures between 14 degrees C and 28 degrees C shortly (3 hr) after food depletion. Increasing time on the gradient reduces the positive thermotactic response at the lowe...

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

authors： Hong CB,Fontana DR,Poff KL

更新日期：1983-09-01 00:00:00

abstract：:Spatial organization of the binding sites for the priming substrate, the template DNA, and the transcription inhibitor rifampicin (Rif) in Escherichia coli RNA polymerase (EC 2.7.7.6) was probed with chimeric compounds in which Rif is covalently attached to a ribonucleotide. The compounds bind to RNA polymerase in bif...

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

authors： Mustaev A,Zaychikov E,Severinov K,Kashlev M,Polyakov A,Nikiforov V,Goldfarb A

更新日期：1994-12-06 00:00:00

abstract：:The regulation of major histocompatibility complex class II gene expression is directly involved in the control of normal and abnormal immune responses. In humans, HLA-DR, -DQ, and -DP class II heterodimers are encoded by a family of alpha- and beta-chain genes clustered in the major histocompatibility complex. Their ...

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

authors： Reith W,Barras E,Satola S,Kobr M,Reinhart D,Sanchez CH,Mach B

更新日期：1989-06-01 00:00:00

abstract：:Myxococcus xanthus is a Gram-negative bacterium that aggregates to form fruiting bodies when nutrients are limiting. Previous studies showed that the frz mutants that are defective in chemotaxis exhibited irregular and infrequent patterns of cellular reversal. In contrast, wild-type cells, when examined individually, ...

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

authors： Shi W,Ngok FK,Zusman DR

更新日期：1996-04-30 00:00:00

abstract：:Conjugative relaxases are the proteins that initiate bacterial conjugation by a site-specific cleavage of the transferred DNA strand. In vitro, they show strand-transferase activity on single-stranded DNA, which suggests they may also be responsible for recircularization of the transferred DNA. In this work, we show t...

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

authors： Draper O,César CE,Machón C,de la Cruz F,Llosa M

更新日期：2005-11-08 00:00:00

abstract：:Molecular chaperones are an essential part of the machinery that avoids protein aggregation and misfolding in vivo. However, understanding the molecular basis of how chaperones prevent such undesirable interactions requires the conformational changes within substrate proteins to be probed during chaperone action. Here...

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

authors： Kellner R,Hofmann H,Barducci A,Wunderlich B,Nettels D,Schuler B

更新日期：2014-09-16 00:00:00

abstract：:Unfolded RNase A is known to contain an equilibrium mixture of two forms, a slow-folding form (U(1)) and a fast-folding form (U(2)). If U(1) is produced after unfolding by the slow cis-trans isomerization of proline residues about X-Pro imide bonds, then the formation of U(1) should be catalyzed by strong acids. There...

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

authors： Schmid FX,Baldwin RL

更新日期：1978-10-01 00:00:00

abstract：:Misalignment between internal circadian rhythmicity and externally imposed behavioral schedules, such as occurs in shift workers, has been implicated in elevated risk of metabolic disorders. To determine underlying mechanisms, it is essential to assess whether and how peripheral clocks are disturbed during shift work ...

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

authors： Skene DJ,Skornyakov E,Chowdhury NR,Gajula RP,Middleton B,Satterfield BC,Porter KI,Van Dongen HPA,Gaddameedhi S

更新日期：2018-07-24 00:00:00

abstract：:The kidney has an extraordinary ability to maintain stable fractional solute and fluid reabsorption over a wide range of glomerular filtration rates (GFRs). Internalization of filtered low molecular weight proteins, vitamins, hormones, and other small molecules is mediated by the proximal tubule (PT) multiligand recep...

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

authors： Raghavan V,Rbaibi Y,Pastor-Soler NM,Carattino MD,Weisz OA

更新日期：2014-06-10 00:00:00

abstract：:We have selected from a mixture of random polynucleotides an RNA that is able to replicate in the presence of the DNA-dependent RNA polymerase of Escherichia coli, provided the medium contains Mn(2+) and ITP, in addition to ATP, CTP, and UTP. The RNA consists of a chain of about 125 (+/-25) nucleotides and appears to ...

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

authors： Biebricher CK,Orgel LE

更新日期：1973-03-01 00:00:00

abstract：:A varying oxygen environment is known to affect cellular function in disease as well as activity of various therapeutics. For transient structures, whether they are unconstrained therapeutic transplants, migrating cells during tumor metastasis, or cell populations induced by an immunological response, the role of oxyg...

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

authors： Spanoudaki V,Doloff JC,Huang W,Norcross SR,Farah S,Langer R,Anderson DG

更新日期：2019-03-12 00:00:00

abstract：:Cyclic GMP (cGMP) is an important second messenger in eukaryotes. It is formed by guanylyl cyclases (GCs), members of the nucleotidyl cyclases class III, which also comprises adenylyl cyclases (ACs) from most organisms. To date, no structures of eukaryotic GCs are available, and all bacterial class III proteins were f...

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

authors： Rauch A,Leipelt M,Russwurm M,Steegborn C

更新日期：2008-10-14 00:00:00

abstract：:To identify genetic factors that interact with social environments to impact human health, we used a bioinformatic strategy that couples expression array-based detection of environmentally responsive transcription factors with in silico discovery of regulatory polymorphisms to predict genetic loci that modulate transc...

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

authors： Cole SW,Arevalo JM,Takahashi R,Sloan EK,Lutgendorf SK,Sood AK,Sheridan JF,Seeman TE

更新日期：2010-03-23 00:00:00

abstract：:Epstein-Barr virus (EBV)-genome-negative human lymphoma lines, Ramos and BJAB, can be converted by EBV in vitro into EBV-genome-positive virus nonproducer lines. These cell lines have been used to identify surface antigens unique to EBV, with the expectation that such determinants might be related to the antigenic tar...

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

authors： Lasky RD,Troy FA

更新日期：1984-01-01 00:00:00

abstract：:Because of increased numbers of recorded pertussis cases in the United States, this study sought to understand the role of nonmedical vaccine exemptions and waning immunity may have had on the resurgence of pertussis in the United States at the community level. We used geospatial scan statistics, SaTScan, version 9.4,...

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

authors： Aloe C,Kulldorff M,Bloom BR

更新日期：2017-07-03 00:00:00

abstract：:Discrete state models are a common tool of modeling in many areas. E.g., Markov state models as a particular representative of this model family became one of the major instruments for analysis and understanding of processes in molecular dynamics (MD). Here we extend the scope of discrete state models to the case of s...

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

authors： Gerber S,Horenko I

更新日期：2014-10-14 00:00:00

abstract：:The drug resistance factor RP4, originally isolated in Pseudomonas, was transferred to Rhizobium meliloti. In that strain, RP4 promotes conjugational transfer of chromosomal markers to form haploid recombinants. This mating system has been used to construct a linkage map of R. meliloti. ...

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

authors： Meade HM,Signer ER

更新日期：1977-05-01 00:00:00

abstract：:Although Africa is the origin of modern humans, the pattern and distribution of genetic variation and correlations with cultural and linguistic diversity in Africa have been understudied. Recent advances in genomic technology, however, have led to genomewide studies of African samples. In this article, we discuss gene...

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

authors： Scheinfeldt LB,Soi S,Tishkoff SA

更新日期：2010-05-11 00:00:00

abstract：:Preparations of partially purified chloroplast DNA-dependent RNA polymerase from maize and some other plants transcribe cloned chloroplast genes preferentially and much more actively from appropriately negatively supercoiled templates than from relaxed templates. We have found that the polymerase in such fractions doe...

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

authors： Zaitlin D,Hu J,Bogorad L

更新日期：1989-02-01 00:00:00

abstract：:Most higher plants develop severe toxicity symptoms when grown on ammonium (NH(4)(+)) as the sole nitrogen source. Recently, NH(4)(+) toxicity has been implicated as a cause of forest decline and even species extinction. Although mechanisms underlying NH(4)(+) toxicity have been extensively sought, the primary events ...

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

authors： Britto DT,Siddiqi MY,Glass AD,Kronzucker HJ

更新日期：2001-03-27 00:00:00

abstract：:We present a model describing how Mg(2+) binds and stabilizes specific RNA structures. In this model, RNA stabilization arises from two energetically distinct modes of Mg(2+) binding: diffuse- and site-binding. Diffusely bound Mg(2+) are electrostatically attracted to the strong anionic field around the RNA and are ac...

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

authors： Misra VK,Draper DE

更新日期：2001-10-23 00:00:00

abstract：:The generalized seizures of status epilepticus (SE) trigger a series of molecular and cellular events that produce cognitive deficits and can culminate in the development of epilepsy. Known early events include opening of the blood-brain barrier (BBB) and astrocytosis accompanied by activation of brain microglia. Wher...

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

authors： Varvel NH,Neher JJ,Bosch A,Wang W,Ransohoff RM,Miller RJ,Dingledine R

更新日期：2016-09-20 00:00:00

abstract：:This study examines the basis of resistance and sensitivity of normal and transformed cells to histone deacetylase inhibitor (HDACi)-induced cell death, specifically the role of caspases and thioredoxin (Trx). An important attribute of HDACis is that they induce cancer cell death at concentrations to which normal cell...

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

authors： Ungerstedt JS,Sowa Y,Xu WS,Shao Y,Dokmanovic M,Perez G,Ngo L,Holmgren A,Jiang X,Marks PA

更新日期：2005-01-18 00:00:00

abstract：:Tropical forests hold most of Earth's biodiversity. Their continued loss through deforestation and agriculture is the main threat to species globally, more than disease, invasive species, and climate change. However, not all tropical forests have the same ability to sustain biodiversity. Those that have been disturbed...

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

authors： Hedges SB,Cohen WB,Timyan J,Yang Z

更新日期：2018-11-13 00:00:00

abstract：:It has been reported that expression of familial amyotrophic lateral sclerosis (FALS)-associated mutant Cu/Zn superoxide dismutase-1 (SOD) induces apoptosis of neuronal cells in culture associated with an increase in reactive oxygen species. SOD recently has been shown to prevent calcineurin inactivation, initiating t...

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

authors： Lee JP,Palfrey HC,Bindokas VP,Ghadge GD,Ma L,Miller RJ,Roos RP

更新日期：1999-03-16 00:00:00

abstract：:The specific nucleocytoplasmic compartmentalization of proteins has been examined for some major soluble acidic nuclear proteins in oocytes of different amphibia. Proteins synthesized and radioactively labeled by translation in vitro, by using mRNA from ovaries of the frog Xenopus laevis, were injected into the cytopl...

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

authors： Dabauvalle MC,Franke WW

更新日期：1982-09-01 00:00:00

abstract：:Many cyanobacteria alter their phycobilisome composition in response to changes in light wavelength in a process termed complementary chromatic adaptation. Mutant strains FdR1 and FdR2 of the filamentous cyanobacterium Fremyella diplosiphon are characterized by aberrant chromatic adaptation. Instead of adjusting to di...

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

authors： Chiang GG,Schaefer MR,Grossman AR

更新日期：1992-10-15 00:00:00

abstract：:Glial cells are traditionally regarded as elements for structural support and ionic homeostasis, but have recently attracted attention as putative integral elements of the machinery involved in synaptic transmission and plasticity. Here, we demonstrate that calcium-binding protein S100B, which is synthesized in consid...

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

authors： Nishiyama H,Knopfel T,Endo S,Itohara S

更新日期：2002-03-19 00:00:00

abstract：:The Na,K-ATPase contains a binding site for cardiac glycosides, such as ouabain, digoxin, and digitoxin, which is highly conserved among species ranging from Drosophila to humans. Although advantage has been taken of this site to treat congestive heart failure with drugs such as digoxin, it is unknown whether this sit...

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

authors： Dostanic-Larson I,Van Huysse JW,Lorenz JN,Lingrel JB

更新日期：2005-11-01 00:00:00

abstract：:Using a water-based prebiotic model of sugar synthesis involving glycolaldehyde self-condensation, we demonstrate that homochiral L-dipeptide catalysts lead to the stereospecific syntheses of tetroses. The asymmetric effect is largest for erythrose, which may reach a D-enantiomeric excess of >80% with L-Val-L-Val cata...

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

authors： Weber AL,Pizzarello S

更新日期：2006-08-22 00:00:00