Layer-specific variation of iron content in cerebral cortex as a source of MRI contrast.

abstract：:Analysis of commercial catches reveals a serial depletion of some oceanic fish stocks over time, resulting in fisheries focusing on increasingly smaller species closer to the base of the food chain. This effect, described as fishing down the marine food web, is observed when the trophic level of the catch declines ove...

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

authors： Dunlop ES,Goto D,Jackson DA

更新日期：2019-10-01 00:00:00

abstract：:Depression, the most prevalent mental illness, is underdiagnosed and undertreated, highlighting the need to extend the scope of current screening methods. Here, we use language from Facebook posts of consenting individuals to predict depression recorded in electronic medical records. We accessed the history of Faceboo...

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

authors： Eichstaedt JC,Smith RJ,Merchant RM,Ungar LH,Crutchley P,Preoţiuc-Pietro D,Asch DA,Schwartz HA

更新日期：2018-10-30 00:00:00

abstract：:We previously have identified a subpopulation of contact-insensitive (CS-) cells which lacks density-dependent inhibition of cell division in primary and low-passage cultures of Syrian hamster embryonic (SHE) fibroblastic cells. Further, we have shown that the proportion of these CS- cells declines as a result of the ...

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

authors： Nakano S,Ueo H,Bruce SA,Ts'o PO

更新日期：1985-08-01 00:00:00

abstract：:Angiogenin (Ang), an inducer of neovascularization, is secreted by several types of human tumor cells and appears critical for their growth. The murine anti-Ang monoclonal antibody (mAb) 26-2F neutralizes the activities of Ang and dramatically prevents the establishment and metastatic dissemination of human tumor cell...

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

authors： Piccoli R,Olson KA,Vallee BL,Fett JW

更新日期：1998-04-14 00:00:00

abstract：:Techniques of fluorescence and ion microscopies were combined to study the free [Ca2+] and total Ca in NIH 3T3 fibroblast and L6 rat myoblast cells. Free Ca2+ measurements with the Ca2+ indicator fura-2 and digital imaging reveal an inhomogeneous distribution of free cytoplasmic Ca2+ in both cell lines. Fura-2 also re...

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

authors： Chandra S,Gross D,Ling YC,Morrison GH

更新日期：1989-03-01 00:00:00

abstract：:An unprecedented, spontaneous, and complete cleavage of the triple bond of N2 in the thermal reaction of 15N2 with Ta214N+ was observed experimentally by Fourier transform ion cyclotron resonance mass spectrometry; mechanistic aspects of the degenerate ligand exchange were addressed by high-level quantum chemical calc...

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

authors： Geng C,Li J,Weiske T,Schwarz H

更新日期：2019-10-22 00:00:00

abstract：:Rad51 is the primary eukaryotic recombinase responsible for initiating DNA strand exchange during homologous recombination. Although the subject of intense study for over a decade, many molecular details of the reactions promoted by Rad51 and related recombinases remain unknown. Using total internal reflection fluores...

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

authors： Granéli A,Yeykal CC,Robertson RB,Greene EC

更新日期：2006-01-31 00:00:00

abstract：:Restriction site variation in DNA that encodes rRNA (rDNA) was surveyed among 714 offspring within 31 lineages (26 genotypes) of obligate asexually reproducing Taraxacum officinale (dandelions). Although clonal offspring are expected, plants with nonparental rDNA were produced from two parents that were themselves sib...

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

authors： King LM,Schaal BA

更新日期：1990-02-01 00:00:00

abstract：:To elucidate the roles of IgE antibody in host responses to helminth infection, selective IgE-deficient SJA/9 mice were infected with the nematode parasites Nippostrongylus brasiliensis, which elicits remarkable potentiated IgE production, and Trichinella spiralis, which induces strong anti-Trichinella IgE antibody pr...

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

authors： Watanabe N,Katakura K,Kobayashi A,Okumura K,Ovary Z

更新日期：1988-06-01 00:00:00

abstract：:A hypothetical gene with similarity to the ispD gene of Escherichia coli was cloned from Arabidopsis thaliana cDNA. The ORF of 909 bp specifies a protein of 302 amino acid residues. The cognate chromosomal gene consists of 2,071 bp and comprises 11 introns with a size range of 78-202 bp. A fragment comprising amino ac...

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

authors： Rohdich F,Wungsintaweekul J,Eisenreich W,Richter G,Schuhr CA,Hecht S,Zenk MH,Bacher A

更新日期：2000-06-06 00:00:00

abstract：:The formation of nerve-muscle junctions in monolayer cultures of embryonic muscle and spinal cord cells is described. Muscle-forming cells (myoblasts) from leg muscles of 12-day chick embryos were separated with trypsin and cultured on a collagen substrate for two days. Suspensions of ventral spinal cord cells from si...

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

authors： Shimada Y,Fischman DA,Moscona AA

更新日期：1969-03-01 00:00:00

abstract：:An early and a late histone H2B gene from the sea urchin Stronglyocentrotus purpuratus were linked in a single plasmid and injected into the eggs of the sea urchin Lytechinus pictus. The levels of transcripts of injected early and late genes and of endogenous early genes were monitored during development by a ribonucl...

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

authors： Colin AM,Catlin TL,Kidson SH,Maxson R

更新日期：1988-01-01 00:00:00

abstract：:Flowering plants often prevent selfing through mechanisms of self-incompatibility (S.I.). The loss of S.I. has occurred many times independently, because it provides short-term advantages in situations where pollinators or mates are rare. The genus Capsella, which is closely related to Arabidopsis, contains a pair of ...

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

authors： Guo YL,Bechsgaard JS,Slotte T,Neuffer B,Lascoux M,Weigel D,Schierup MH

更新日期：2009-03-31 00:00:00

abstract：:Evolutionary theory reveals that punishment is effective in promoting cooperation and maintaining social norms. Although it is accepted that emotions are connected to punishment decisions, there remains substantial debate over why humans use costly punishment. Here we show experimentally that constraints on emotion ex...

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

authors： Xiao E,Houser D

更新日期：2005-05-17 00:00:00

abstract：:Freshwater planarian flatworms are capable of regenerating complete organisms from tiny fragments of their bodies; the basis for this regenerative prowess is an experimentally accessible stem cell population that is present in the adult planarian. The study of these organisms, classic experimental models for investiga...

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

authors： Newmark PA,Reddien PW,Cebrià F,Sánchez Alvarado A

更新日期：2003-09-30 00:00:00

abstract：:A simple model is proposed to account for large increases in transporter-mediated ion flux across cell membranes that are elicited by small fractional changes of cell volume. The model is based upon the concept that, as a result of large excluded volume effects in cytoplasm (macromolecular crowding), the tendency of s...

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

authors： Minton AP,Colclasure GC,Parker JC

更新日期：1992-11-01 00:00:00

abstract：:In considering the structure of the 30S subunit of the Escherichia coli ribosome, we have assumed that: (i) all or almost all the proteins within the 30S particle are compact and globular, as recently shown for the isolated proteins S4, S7, S8, S15, and S16 in solution [Serdyuk, I.N., Zaccai, G. & Spirin, A.S. (1978) ...

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

authors： Spirin AS,Serdyuk IN,Shpungin JL,Vasiliev VD

更新日期：1979-10-01 00:00:00

abstract：:Effects of temperature on biological processes are complex. Diffusion is less affected than the diverse enzymatic reactions that have distinct individual temperature profiles. Hence thermal fluctuations pose a formidable challenge to ectothermic organisms in which body temperature is largely dictated by the ambient te...

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

authors： Radermacher PT,Myachina F,Bosshardt F,Pandey R,Mariappa D,Müller HA,Lehner CF

更新日期：2014-04-15 00:00:00

abstract：:Colon carcinoma is one of the leading causes of death from cancer and is characterized by a heterogenic pool of cells with distinct differentiation patterns. Recently, it was reported that a population of undifferentiated cells from a primary tumor, so-called cancer stem cells (CSC), can reconstitute the original tumo...

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

authors： Vermeulen L,Todaro M,de Sousa Mello F,Sprick MR,Kemper K,Perez Alea M,Richel DJ,Stassi G,Medema JP

更新日期：2008-09-09 00:00:00

abstract：:The chloroplast coupling factor 1 consists of five nonidentical subunits, three of which (alpha, beta, and epsilon subunits) have been shown in several laboratories to be synthesized within chloroplasts. The site of synthesis of the remaining two (gamma and delta subunits) was investigated by analyzing products direct...

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

authors： Watanabe A,Price CA

更新日期：1982-10-01 00:00:00

abstract：:We have cloned one of the two human alpha-globin genes and report its complete nucleotide sequence. The gene is 832 base pairs (bp) long from the 5'-cap site to the 3'-polyadenylylation site. The amino acid coding sequences are separated into three segments (exons) by two short (117 and 140 bp) intervening sequences. ...

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

authors： Liebhaber SA,Goossens MJ,Kan YW

更新日期：1980-12-01 00:00:00

abstract：:To study the origin of and the degree of T-cell antigen receptor (TCR) diversity of Thy-1+ dendritic epidermal cells (Thy-1+ dECs) in mice, we have developed a monoclonal antibody (mAb 536) to the gamma delta TCR. mAb 536 binds to and stimulates interleukin 2 secretion from Thy-1+ dEC but not cells that express TCR co...

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

authors： Havran WL,Grell S,Duwe G,Kimura J,Wilson A,Kruisbeek AM,O'Brien RL,Born W,Tigelaar RE,Allison JP

更新日期：1989-06-01 00:00:00

abstract：:Group II intron RNAs self-splice in vitro but only at high salt and/or Mg2+ concentrations and have been thought to require proteins to stabilize their active structure for efficient splicing in vivo. Here, we show that a DEAD-box protein, CYT-19, can by itself promote the splicing and reverse splicing of the yeast aI...

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

authors： Mohr S,Matsuura M,Perlman PS,Lambowitz AM

更新日期：2006-03-07 00:00:00

abstract：:Gastrulation is a fundamental process in early development that results in the formation of three primary germ layers. During avian gastrulation, presumptive mesodermal cells in the dorsal epiblast ingress through a furrow called the primitive streak (PS), and subsequently move away from the PS and form adult tissues....

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

authors： Zamir EA,Czirók A,Cui C,Little CD,Rongish BJ

更新日期：2006-12-26 00:00:00

abstract：:In 2012, an unusual outbreak of urban malaria was reported from Djibouti City in the Horn of Africa and increasingly severe outbreaks have been reported annually ever since. Subsequent investigations discovered the presence of an Asian mosquito species; Anopheles stephensi, a species known to thrive in urban environme...

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

authors： Sinka ME,Pironon S,Massey NC,Longbottom J,Hemingway J,Moyes CL,Willis KJ

更新日期：2020-10-06 00:00:00

abstract：:We have used wild-type and variants of the T-lymphoma cell line S49 to explore internalization and down-regulation of adenylate cyclase-linked beta-adrenergic receptors. Internalization was defined by the loss in "surface receptors" detected at 4 degrees C on intact cells by the antagonists [3H]CGP-12177 or [125I]iodo...

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

authors： Mahan LC,Koachman AM,Insel PA

更新日期：1985-01-01 00:00:00

abstract：:Chloroplast DNA (cpDNA) is under great photooxidative stress, yet its evolution is very conservative compared with nuclear or mitochondrial genomes. It can be expected that DNA repair mechanisms play important roles in cpDNA survival and evolution, but they are poorly understood. To gain insight into how the most seve...

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

authors： Kwon T,Huq E,Herrin DL

更新日期：2010-08-03 00:00:00

abstract：:The intracellular localization of phytochrome was seen in dark-grown oat (Avena sativa L., cv. Garry) and rice (Oryza sativa L., cv. unknown) shoots after various light treatments using an indirect peroxidase-antiperoxidase antibody labeling method. Phytochrome is generally distributed throughout the cytoplasm in cell...

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

authors： Mackenzie JM Jr,Coleman RA,Briggs WR,Pratt LH

更新日期：1975-03-01 00:00:00

abstract：:The discovery of arbuscules in Aglaophyton major, an Early Devonian land plant, provides unequivocal evidence that mycorrhizae were established >400 million years ago. Nonseptate hyphac and arbuscules occur in a specialized meristematic region of the cortex that continually provided new cells for fungal infection. Arb...

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

authors： Remy W,Taylor TN,Hass H,Kerp H

更新日期：1994-12-06 00:00:00

abstract：:We report a method for introducing mtDNA mutations into the mouse female germ line by means of embryonic stem (ES) cell cybrids. Mitochondria were recovered from the brain of a NZB mouse by fusion of synaptosomes to a mtDNA-deficient (rho degrees ) cell line. These cybrids were enucleated and the cytoplasts were elect...

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

authors： Sligh JE,Levy SE,Waymire KG,Allard P,Dillehay DL,Nusinowitz S,Heckenlively JR,MacGregor GR,Wallace DC

更新日期：2000-12-19 00:00:00