Abstract:
:Antibody-coated latex beads (Ab-beads) were attached to Leptospira interrogans serovars illini 3055 and icterohaemorrhagiae SC1157. The movement of the Ab-beads relative to the motion of the cells was observed by direct darkfield microscopy or was recorded on videotape. When the Ab-beads were attached to the front end of motile cells, the Ab-beads were displaced towards the back end of the cells. When the cells reversed direction, the Ab-beads also reversed direction. A number of hypotheses were proposed and tested to account for this Ab-bead displacement. The one best supported by the evidence states that the Ab-beads are attached to antigens of the outer membrane sheath. These antigens are dragged laterally through the sheath due to the forward motion of the cells and the retarding forces of the medium acting on the beads. The results obtained provide information on the nature of the outer membrane sheath of L. interrogans, the basis for certain movements of spirochetes, and insight on how spirochetes attach to eukaryotic cells and tissues. In addition, the results indicate that antigens can move laterally through membranes as rapidly as 11 micrometers/sec.
journal_name
Proc Natl Acad Sci U S Aauthors
Charon NW,Lawrence CW,O'Brien Sdoi
10.1073/pnas.78.11.7166subject
Has Abstractpub_date
1981-11-01 00:00:00pages
7166-70issue
11eissn
0027-8424issn
1091-6490journal_volume
78pub_type
杂志文章abstract::Previous studies have shown that DNA methyltransferase (Dnmt) 1 is required for maintenance of bulk DNA methylation and is essential for mouse development. However, somatic disruption of DNMT1 in the human cancer cell line HCT116 was not lethal and caused only minor decreases in methylation. Here, we report the identi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0604602103
更新日期:2006-09-19 00:00:00
abstract::Human-caused environmental changes are creating regional combinations of environmental conditions that, within the next 50 to 100 years, may fall outside the envelope within which many of the terrestrial plants of a region evolved. These environmental modifications might become a greater cause of global species extinc...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.091093198
更新日期:2001-05-08 00:00:00
abstract::The properties of inositol 1,4,5-trisphosphate (InsP3) receptor sites in the anterior pituitary were evaluated by binding studies with InsP3 labeled with 32P to high specific radioactivity. Specific binding of Ins[32P]P3 was demonstrable in pituitary membrane preparations and was linearly proportional to the amount of...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.84.23.8195
更新日期:1987-12-01 00:00:00
abstract::Protein interactions with the collagen triple helix play a critical role in collagen fibril formation, cell adhesion, and signaling. However, structural insight into sequence-specific collagen recognition is limited to an integrin-peptide complex. A GVMGFO motif in fibrillar collagens (O denotes 4-hydroxyproline) bind...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0808452105
更新日期:2008-11-25 00:00:00
abstract::We have transferred the human gene for hypoxanthine-guanine phosphoribosyltransferase (HPRT, EC 2.4.2.8; IMP:pyrophosphate phosphoribosyltransferease) via isolated metaphase chromosomes from human HeLa S3 cells into murine A9 cells which lack functional murine HPRT activity, using the technique of McBride and Ozer (Pr...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.72.5.1792
更新日期:1975-05-01 00:00:00
abstract::RAG1 and RAG2 are lymphoid-specific genes that together induce V(D)J recombinase activity in a variety of nonlymphoid cell types. While no other lymphoid-specific factors are required to induce recombination, other factors with more widespread expression patterns have been implicated in the reaction. However, none of ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.91.13.6156
更新日期:1994-06-21 00:00:00
abstract::Aggregation of the receptor for IgE on mast cells, basophils, and a tumor analog, rat basophilic leukemia (RBL) cells, induces a calcium-dependent degranulation of the cells. We have measured the membrane potential (delta psi) of RBL cells during this reaction by using the tetraphenylphosphonium ion (Ph4P+) equilibrat...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.80.18.5744
更新日期:1983-09-01 00:00:00
abstract::Ca channel currents were studied in freshly dispersed bovine adrenal glomerulosa cells to better understand the control of aldosterone secretion by extracellular K concentration (Ko) and angiotensin II (AII). The whole-cell variation of the patch voltage clamp technique was used. Two types of Ca channels were found. O...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.85.7.2412
更新日期:1988-04-01 00:00:00
abstract::DNA-based identification depends on the probability that two different individuals have the same phenotype, which is given by kinship theory. Together with the large and consistent body of evidence on human population structure, kinship theory provides a sound basis for forensic use of DNA markers. ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.89.7.2556
更新日期:1992-04-01 00:00:00
abstract::There is evidence that interstitial telomere (TTAGGG)n-like sequences at chromosome 2 fragile sites play an important role in the somatic events that characterize the earliest phases of radiation-induced acute myeloid leukemia in the CBA/H mouse. Here we show that the highly inbred CBA/H colony unexpectedly contains f...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.4.1407
更新日期:1993-02-15 00:00:00
abstract::Very thin (2.3-5.5 nm) self-assembled organic dielectric multilayers have been integrated into organic thin-film transistor structures to achieve sub-1-V operating characteristics. These new dielectrics are fabricated by means of layer-by-layer solution phase deposition of molecular silicon precursors, resulting in sm...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0501027102
更新日期:2005-03-29 00:00:00
abstract::Unlike parasitic protist groups that are defined by the absence of mitochondria, the Pelobiontida is composed mostly of free-living species. Because of the presence of ultrastructural and cellular features that set them apart from all other eukaryotic organisms, it has been suggested that pelobionts are primitively am...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.95.20.11769
更新日期:1998-09-29 00:00:00
abstract::We have asked here how the remarkable variation in maize haplotype structure affects recombination. We compared recombination across a genetic interval of 9S in 2 highly dissimilar heterozygotes that shared 1 parent. The genetic interval in the common haplotype is approximately 100 kb long and contains 6 genes intersp...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0902972106
更新日期:2009-05-26 00:00:00
abstract::A 3- to 5-year cycle of vole abundances is a characteristic phenomenon in the ecology of northern regions, and their explanation stands as a central theoretical challenge in population ecology. Although many species of voles usually coexist and are in severe competition for food and breeding space, the role of intersp...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.96.3.986
更新日期:1999-02-02 00:00:00
abstract::Because synaptic vesicle exocytosis is a nano-mechanical process, it should be influenced by the mechanical properties of the cell membrane to which the vesicle fuses. By dissolving surfactants at various concentrations in the neuronal membrane, we have perturbed mechanical properties of the membrane and have found th...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0809714105
更新日期:2008-11-18 00:00:00
abstract::The constant heavy chain (CH1) domain affects antibody affinity and fine specificity, challenging the paradigm that only variable regions contribute to antigen binding. To investigate the role of the CH1 domain, we constructed IgA2 from the broadly neutralizing anti-HIV-1 2F5 IgG1, and compared 2F5 IgA2 and IgG bindin...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1200024109
更新日期:2012-07-31 00:00:00
abstract::To identify the binding domain for dihydropyridine Ca2+ antagonists, skeletal muscle Ca2+ channels were photolabeled with [3H](+)-PN200-110 and [3H]azidopine. Regions of alpha 1 photolabeled by these ligands were then identified by antibody mapping of proteolytic fragments. Approximately 50% of the specific labeling b...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.88.23.10769
更新日期:1991-12-01 00:00:00
abstract::Proteins that recognize the core sequence GATA are important regulators of hematopoietic-specific gene transcription. We have characterized cDNAs encoding the Xenopus laevis homologues of three related transcription factors, designated GATA-1, -2, and -3. Comparative sequence analysis reveals strong conservation of th...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.88.23.10642
更新日期:1991-12-01 00:00:00
abstract::We describe a physical map of the end of the long arm of the human X chromosome encompassing the region from Xq27.2 to the q telomere, inclusive of the chromosomal band Xq28. This region is of particular interest, since it contains the highest density of genes associated with genetic diseases. The map covers a total o...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.88.19.8302
更新日期:1991-10-01 00:00:00
abstract::Focal electric stimulation of the auditory cortex is well suited for exploration of the function of the corticofugal (descending) system and the neural mechanism of plasticity in the central auditory system, because it evokes changes in frequency-tuning, called best frequency (BF) shifts, as does auditory fear conditi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0509761102
更新日期:2005-12-27 00:00:00
abstract::Membrane-mediated particle interactions depend both on the properties of the particles themselves and the membrane environment in which they are suspended. Experiments have shown that chiral rod-like inclusions dissolved in a colloidal membrane of opposite handedness assemble into colloidal rafts, which are finite-siz...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1900615116
更新日期:2019-08-06 00:00:00
abstract::Despite high predation pressure, planktonic copepods remain one of the most abundant groups on the planet. Their escape response provides one of most effective mechanisms to maximize evolutionary fitness. Owing to their small size (100 µm) compared with their predators (>1 mm), increasing viscosity is believed to have...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1212148110
更新日期:2013-03-19 00:00:00
abstract::By harnessing the oxidative power of microorganisms, energy can be recovered from reservoirs of less-concentrated organic matter, such as marine sediment, wastewater, and waste biomass. Left unmanaged, these reservoirs can become eutrophic dead zones and sites of greenhouse gas generation. Here, we introduce a unique ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1307327110
更新日期:2013-10-01 00:00:00
abstract::We have devised a class of isothermal reactions for amplifying DNA. These homogeneous reactions rapidly synthesize short oligonucleotides (8-16 bases) specified by the sequence of an amplification template. Versions of the reactions can proceed in either a linear or an exponential amplification mode. Both of these rea...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0730811100
更新日期:2003-04-15 00:00:00
abstract::The p53 protein is an attractive target for immunotherapy, because mutations in the p53 gene are the most common genetic alterations found in human tumors. These mutations result in high levels of p53 protein in the tumor cell, whereas the expression level of wild-type p53 in nonmalignant tissue is usually much lower....
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.93.10.4781
更新日期:1996-05-14 00:00:00
abstract::Urbanization represents an extreme transformation of more natural systems. Populations of most species decline or disappear with urbanization, and yet some species persist and even thrive in cities. What determines which species persist or thrive in urban habitats? Direct competitive interactions among species can inf...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1809317115
更新日期:2018-12-04 00:00:00
abstract::Elucidation of the genetic control of rice architecture is crucial due to the global demand for high crop yields. Rice architecture is a complex trait affected by plant height, tillering, and panicle morphology. In this study, principal component analysis (PCA) on 8 typical traits related to plant architecture reveale...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1904964116
更新日期:2019-10-15 00:00:00
abstract::The c-ras family is a set of c-onc genes that are highly conserved in vertebrates. The genes in this family are homologous to the transforming genes of Harvey and Kirsten murine sarcoma viruses (v-Ha-ras and v-Ki-ras, respectively). Using an in situ molecular hybridization method, we detected three sites on the human ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.80.15.4794
更新日期:1983-08-01 00:00:00
abstract::Most climate models are large dynamical systems involving a million (or more) variables on big computers. Given that they are nonlinear and not perfect, what can we expect to learn from them about the earth's climate? How can we determine which aspects of their output might be useful and which are noise? And how shoul...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.012580599
更新日期:2002-02-19 00:00:00
abstract::The β-1,3-glucan chrysolaminarin is the main storage polysaccharide of diatoms. In contrast to plants and green algae, diatoms and most other algal groups do not accumulate storage polysaccharides in their plastids. The diatom Phaeodactylum tricornutum possesses only a single gene encoding a putative β-1,3-glucan synt...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1719274115
更新日期:2018-05-01 00:00:00