Abstract:
:The ribosomal RNA genes (rDNA) of Tetrahymena thermophila macronucleus exist as free linear 21-kilobase molecules that contain replication origins and telomeres. A mutation in this gene confers resistance to the antibiotic paromomycin. We have isolated rDNA from such a mutant (strain p2f), microinjected it into the macronucleus of a sensitive strain, and obtained drug-resistant cells at a frequency of 1-3%. The transformed cells have a distinct and stable phenotype. The rDNA of the transformants contains the expected sequences of the mutant rDNA as determined by oligonucleotide hybridization. rDNA from a different inbred line (C3-368), which contains heteromorphic restriction sites, has also been used for injection, and the results confirm the fact that the injected rDNA is indeed present in the transformants. Injection of rDNA from the C3 strains also increases the transformation frequency 5- to 10-fold and leads to the total replacement of the resident rDNA of the B-inbred strains. This is presumably due to the replication dominance of rDNA from the C3 strains over that of the B strains. Using this method, we have also been able to transform developing cells, at similar frequencies, by microinjecting into the macronuclear anlagen.
journal_name
Proc Natl Acad Sci U S Aauthors
Tondravi MM,Yao MCdoi
10.1073/pnas.83.12.4369subject
Has Abstractpub_date
1986-06-01 00:00:00pages
4369-73issue
12eissn
0027-8424issn
1091-6490journal_volume
83pub_type
杂志文章abstract::A major challenge of cancer immunotherapy is the persistence and outgrowth of subpopulations that lose expression of the target antigen. IL-15 is a potent cytokine that can promote organ-specific autoimmunity when up-regulated on tissue cells. Here we report that T cells eradicated 2-wk-old solid tumors that expressed...
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.1301022110
更新日期:2013-05-14 00:00:00
abstract::Capturing carbon dioxide from the atmosphere ("air capture") in an industrial process has been proposed as an option for stabilizing global CO(2) concentrations. Published analyses suggest these air capture systems may cost a few hundred dollars per tonne of CO(2), making it cost competitive with mainstream CO(2) miti...
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.1012253108
更新日期:2011-12-20 00:00:00
abstract::Several polypeptides contained in the coat and the core of adenovirus type 2 particles have been identified as virus gene products. They are synthesized in vitro by a cell-free protein-making system programmed by adenovirus type 2 messenger RNA that has been hybridized with and eluted from virus DNA. Fractionation by ...
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.71.9.3385
更新日期:1974-09-01 00:00:00
abstract::Antibodies have been prepared to the core protein of cartilage chondroitin sulfate proteoglycan from clones isolated after fusion of rat spleen cells and mouse myeloma cell lines. Antibodies produced by five clones were studied in detail by a radioimmunoassay utilizing 35SO42-labeled hyaluronidase-digested chondroitin...
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.77.7.3971
更新日期:1980-07-01 00:00:00
abstract::We show that a large class of finite factors has free entropy dimension less than or equal to one. This class includes all prime factors and many property T factors. ...
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.97.18.9881
更新日期:2000-08-29 00:00:00
abstract::The eyes of some aquatic animals form images through reflective optics. Shrimp, lobsters, crayfish, and prawns possess reflecting superposition compound eyes, composed of thousands of square-faceted eye units (ommatidia). Mirrors in the upper part of the eye (the distal mirror) reflect light collected from many ommati...
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.1722531115
更新日期:2018-03-06 00:00:00
abstract::The primary structure of the Escherichia coli hemolysin polypeptide (HlyA) is used to predict intramolecular structures involved in the secretion and cytolytic activity of the molecule. The C-terminal region of HlyA contains a repeated, 8-amino acid chain represented by the consensus sequence Leu-Xaa-Gly-Gly-Xaa-Gly-A...
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.85.14.5269
更新日期:1988-07-01 00:00:00
abstract::A simple in vitro system that supports chromatin assembly was developed for Saccharomyces cerevisiae. The assembly reaction is ATP-dependent, uses soluble histones and assembly factors, and generates physiologically spaced nucleosomes. We analyze the pathway of histone recruitment into nucleosomes, using this system i...
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.94.17.9034
更新日期:1997-08-19 00:00:00
abstract::In the cell, proteins are synthesized from N to C terminus and begin to fold during translation. Cotranslational folding mechanisms are therefore linked to elongation rate, which varies as a function of synonymous codon usage. However, synonymous codon substitutions can affect many distinct cellular processes, which h...
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.1907126117
更新日期:2020-02-18 00:00:00
abstract::Despite significant infiltration into tumors and atherosclerotic plaques, the role of T lymphocytes in these pathological conditions is still unclear. We have demonstrated that tumor-infiltrating lymphocytes (TILs) and plaque-infiltrating lymphocytes (PILs) produce heparin-binding epidermal growth factor-like growth 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.92.14.6547
更新日期:1995-07-03 00:00:00
abstract::We examined the contributions of the human pulvinar to goal directed selection of visual targets in 3 patients with chronic, unilateral lesions involving topographic maps in the ventral pulvinar. Observers completed 2 psychophysical tasks in which they discriminated the orientation of a lateralized target grating in t...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 临床试验,杂志文章
doi:10.1073/pnas.0810086106
更新日期:2009-03-10 00:00:00
abstract::Regeneration of appendages is frequent among invertebrates as well as some vertebrates. However, in mammals this has been largely relegated to digit tip regeneration, as found in mice and humans. The regenerated structures are formed from a mound of undifferentiated cells called a blastema, found just below the site 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.1118017108
更新日期:2011-12-20 00:00:00
abstract::Plants produce a wide range of allelochemicals to defend against herbivore attack, and generalist herbivores have evolved mechanisms to avoid, sequester, or detoxify a broad spectrum of natural defense compounds. Successful arthropod pests have also developed resistance to diverse classes of pesticides and this adapta...
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.1213214110
更新日期:2013-01-08 00:00:00
abstract::The proteolytic cleavage of sterol regulatory element-binding proteins (SREBPs) is regulated by SREBP cleavage-activating protein (SCAP), which forms complexes with SREBPs in membranes of the endoplasmic reticulum (ER). In sterol-depleted cells, SCAP facilitates cleavage of SREBPs by Site-1 protease, thereby initiatin...
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.96.20.11235
更新日期:1999-09-28 00:00:00
abstract::Heavy (H) chain binding protein (BiP), which binds to free immunoglobulin H chain of the mu and gamma classes, can be demonstrated in pre-B-cells. It is proposed that the displacement of BiP from H chain by light (L) chain terminates the activity of the enzyme system, L-generase, which catalyzes DNA rearrangement at t...
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.79.22.6976
更新日期:1982-11-01 00:00:00
abstract::Data are presented that demonstrate that a dose of 10 R of x-rays to mature oocytes in Drosophila causes a significant increase, more than double the spontaneous frequency, of inherited translocations. The dose-frequency relationship appears to fit best a linear response between 10 and 50 R. From 50 to 500 R, the freq...
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.68.6.1095
更新日期:1971-06-01 00:00:00
abstract::Leaf-cutting ants combine large-scale herbivory with fungus farming to sustain advanced societies. Their stratified colonies are major evolutionary achievements and serious agricultural pests, but the crucial adaptations that allowed this mutualism to become the prime herbivorous component of neotropical ecosystems ha...
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.1212709110
更新日期:2013-01-08 00:00:00
abstract::Homeobox 9 (HOXB9), a nontransforming transcription factor overexpressed in breast cancer, alters tumor cell fate and promotes tumor progression and metastasis. Here we show that HOXB9 confers resistance to ionizing radiation by promoting DNA damage response. In nonirradiated cells, HOXB9 induces spontaneous DNA damag...
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.1018867108
更新日期:2012-02-21 00:00:00
abstract::Infected cell protein 0 (ICP0) of herpes simplex virus 1, a multifunctional ring finger protein, enhances the expression of genes introduced into cells by infection or transfection, interacts with numerous cellular and viral proteins, and is associated with the degradation of several cellular proteins. Sequences encod...
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.022531599
更新日期:2002-01-22 00:00:00
abstract::Ribonuclease H (EC 3.1.4.34) has been used to remove selectively much of the 3'-terminal poly(adenylic acid) [poly(A)] from poliovirus RNA by treating the RNA with the enzyme in the presence of poly(dT). Over 80% of the poly(A) could be removed and the residuum was found as oligo(A) stretches attached to many or all 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.71.8.2983
更新日期:1974-08-01 00:00:00
abstract::Two endocytic receptors, the low density lipoprotein (LDL) receptor (LDLR) and the LDLR-related protein (LRP), are thought to act in concert in the hepatic uptake of partially metabolized dietary lipoproteins, the chylomicron remnants. We have evaluated the role of these two receptors in the hepatic metabolism of chyl...
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.92.10.4611
更新日期:1995-05-09 00:00:00
abstract::To determine which of seven library design algorithms best introduces new protein function without destroying it altogether, seven combinatorial libraries of green fluorescent protein variants were designed and synthesized. Each was evaluated by distributions of emission intensity and color compiled from measurements ...
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.0609647103
更新日期:2007-01-02 00:00:00
abstract::Occurrence of the transversion mutation A.T to C.G is specifically enhanced in Escherichia coli mutT mutants. With the aid of the cloned mutT gene, the MutT protein, which has a molecular mass of 15 kilodaltons, was overproduced and purified to near homogeneity. The protein catalyzes hydrolysis of dGTP to dGMP. dGDP a...
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.86.11.3949
更新日期:1989-06-01 00:00:00
abstract::The positions of transition states along reaction coordinates (r++) for simple chemical reactions are often estimated from Leffler alpha values, the slope of plots of DeltaG++ (activation energy) versus DeltaG(0) (equilibrium free energy) for a series of structural variants. Protein folding is more complex than simple...
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.0406091101
更新日期:2004-10-05 00:00:00
abstract::Transfer RNA (tRNA) is essential for decoding the genome sequence into proteins. In Archaea, previous studies have revealed unique multiple intron-containing tRNAs and tRNAs that are encoded on 2 separate genes, so-called split tRNAs. Here, we discovered 10 fragmented tRNA genes in the complete genome of the hyperther...
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.0808246106
更新日期:2009-02-24 00:00:00
abstract::On illuminating chloroplasts with "short-wavelength" monochromatic light that supports oxygen evolution, spectral evidence was obtained for a new photoreactive chloroplast component, provisionally designated C550, which shows a reversible decrease of absorbance with a maximum at 550 mmu. The light-induced absorbance c...
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.63.3.963
更新日期:1969-07-01 00:00:00
abstract::The nucleus accumbens is considered a critical target of the action of drugs of abuse. In this nucleus a "shell" and a "core" have been distinguished on the basis of anatomical and histochemical criteria. The present study investigated the effect in freely moving rats of intravenous cocaine, amphetamine, and morphine ...
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.92.26.12304
更新日期:1995-12-19 00:00:00
abstract::Targeted gene modification mediated by single-stranded oligonucleotides (SSOs) holds great potential for widespread use in a number of biological and biomedical fields, including functional genomics and gene therapy. By using this approach, specific genetic changes have been created in a number of prokaryotic and euka...
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.0406991102
更新日期:2005-02-15 00:00:00
abstract::Scholander and his coworkers have described in These Proceedings several experiments in which the osmotic pressure exerted by colloidal particles appears to be altered when the particles are subject to an external force; they interpret the experiments as showing that the traditional explanation of osmotic pressure is ...
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.71.8.3182
更新日期:1974-08-01 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
pub_type: 杂志文章
doi:10.1073/pnas.79.20.6304
更新日期:1982-10-01 00:00:00