Abstract:
:We have used oligonucleotide-directed mutagenesis to make a specific change in the beta-lactamase (EC 3.5.2.6) (ampicillin resistance) gene of the plasmid pBR322. Evidence suggests that the active site for this enzyme may include a serine-threonine dyad (residues 70 and 71). By priming in vitro DNA synthesis with a chemically synthesized 16-base oligodeoxyribonucleotide, we have inverted the Ser-Thr dyad to Thr-Ser and thereby generated a mutant with an ampicillin-sensitive phenotype. This "double-mismatch" method is relatively simple and also very general because detection of mutants is at the level of DNA and involves only colony hybridization. Accordingly, the procedure can be applied to any DNA sequence and does not depend on the phenotype of the mutant.
journal_name
Proc Natl Acad Sci U S Aauthors
Dalbadie-McFarland G,Cohen LW,Riggs AD,Morin C,Itakura K,Richards JHdoi
10.1073/pnas.79.21.6409subject
Has Abstractpub_date
1982-11-01 00:00:00pages
6409-13issue
21eissn
0027-8424issn
1091-6490journal_volume
79pub_type
杂志文章abstract::Cells of the human embryonic stem (hES) cell line H9, when cultured in the form of embryoid bodies, give rise to cells with markers of the keratinocyte of stratified squamous epithelia. Keratinocytes also form in nodules produced in scid mice by injected H9 cells; the hES-derived keratinocytes could be recovered in cu...
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.0510953103
更新日期:2006-02-07 00:00:00
abstract::We investigated the participation of genomic regulatory events in the response of the songbird brain to a natural auditory stimulus of known physiological and behavioral relevance, birdsong. Using in situ hybridization, we detected a rapid increase in forebrain mRNA levels of an immediate-early gene encoding a transcr...
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.89.15.6818
更新日期:1992-08-01 00:00:00
abstract::We investigated the effects of beta-estradiol on the locomotor behavior of female mice in a radial maze. Data comprising the total distance traveled during each arm entry were obtained from video records of six consecutive daily recording sessions. Distributions of these data were bimodal for both ovariectomized contr...
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.0607258103
更新日期:2006-10-17 00:00:00
abstract::Redistribution of specialized molecules in migrating cells develops asymmetry between two opposite cell poles, the leading edge and the uropod. We show that acquisition of a motile phenotype in T lymphocytes results in the asymmetric redistribution of ganglioside GM3- and GM1-enriched raft domains to the leading edge ...
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.171160298
更新日期:2001-08-14 00:00:00
abstract::p21Sdi1 (also known as Cip1 and Waf1), an inhibitor of DNA synthesis cloned from senescent human fibroblasts, is an inhibitor of G1 cyclin-dependent kinases (Cdks) in vitro and is transcriptionally regulated by wild-type p53. In addition, p21Sdi1 has been found to inhibit DNA replication by direct interaction with pro...
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.92.10.4352
更新日期:1995-05-09 00:00:00
abstract::The preliminary structural characterization of a reversible ferrous dioxygen complex is reported. Mono(N-methyl imidazole) (dioxygen) meso-tetra (alpha,alpha,alpha,alpha-o-pivalamidephenyl) porphinatorino(II), [Fe(O(2))-(N-Me imid) (alpha,alpha,alpha,alpha-TpivPP)], 1, isolated from toluene solution, crystallizes in 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.71.4.1326
更新日期:1974-04-01 00:00:00
abstract::Hierarchical cellular structures are ubiquitous in nature because of their low-density, high-specific properties, and multifunctionality. Inspired by these systems, we created lightweight ceramic architectures composed of closed-cell porous struts patterned in the form of hexagonal and triangular honeycombs by 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.1616769114
更新日期:2017-02-21 00:00:00
abstract::Branched polyethylenimine (PEI) chains with an average molecular mass of 2 kDa (PEI2) have been covalently attached to gold nanoparticles (GNPs), and the potency of the resulting PEI2-GNPs conjugates as vectors for the delivery of plasmid DNA into monkey kidney (COS-7) cells in the presence of serum in vitro has been ...
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.1233634100
更新日期:2003-08-05 00:00:00
abstract::High-pressure methods are increasingly used to produce new dense materials with unusual properties. Increasing efforts to understand the reaction mechanisms at the microscopic level, to set up and optimize synthetic approaches, are currently directed at carbon-based solids. A fundamental, but still unsolved, question ...
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.0802269105
更新日期:2008-06-03 00:00:00
abstract::By using a mixture of synthetic oligodeoxyribonucleotides as a probe, cloned cDNA sequences specific for low molecular weight (LMW) kininogen have been isolated from a cDNA library of bovine liver mRNA sequences. Nucleotide sequence analyses of cloned cDNA inserts have revealed that bovine liver LMW kininogens are enc...
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.80.1.90
更新日期:1983-01-01 00:00:00
abstract::GSTs catalyze the conjugation of glutathione with a wide variety of hydrophobic compounds, generally resulting in nontoxic products that can be readily eliminated. In contrast to many other organisms, the malarial parasite Plasmodium falciparum possesses only one GST isoenzyme (PfGST). This GST is highly abundant in 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.2333763100
更新日期:2003-11-25 00:00:00
abstract::The compact steep-spectrum sources (CSSs) are an interesting class of objects which are of subgalactic dimensions; they occur more frequently in high-frequency surveys because their spectra often turn over at lower frequencies. We have estimated the symmetry parameters of a well-defined sample of CSSs and compared the...
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.92.25.11417
更新日期:1995-12-05 00:00:00
abstract::Tumor metastasis is the cause of most cancer deaths. Although metastases can form in multiple end organs, the liver is recognized as a highly permissive organ. Nevertheless, there is evidence for immune cell-mediated mechanisms that function to suppress liver metastasis by certain tumors, although the underlying mecha...
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.1617903113
更新日期:2016-12-06 00:00:00
abstract::Active opioid binding proteins were solubilized from rat brain membranes in high yield with sodium deoxycholate in the presence of NaCl. Purification of opioid binding proteins was accomplished by opioid antagonist affinity chromatography. Chromatography using the delta-opioid antagonist N,N-diallyl-Tyr-D-Leu-Gly-Tyr-...
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.91.10.4574
更新日期:1994-05-10 00:00:00
abstract::The balance between mitochondrial fusion and fission influences the reticular shape of mitochondria in yeasts. Little is known about whether mitochondria fusion occurs in plants. Plant mitochondria are usually more numerous and more grain-shaped than animal mitochondria. BLAST searches of the nuclear and mitochondrial...
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.0401077101
更新日期:2004-05-18 00:00:00
abstract::Species- and strain-specific spontaneously occurring tumors have been observed in rodents maintained under normal laboratory conditions. Elucidation of the molecular mechanisms associated with the development of these spontaneous tumors may provide a better understanding of tumor development associated with exposure 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.83.1.33
更新日期:1986-01-01 00:00:00
abstract::Many discoveries in cell biology rely on making specific proteins visible within their native cellular environment. There are various genetically encoded tags, such as fluorescent proteins, developed for fluorescence microscopy (FM). However, there are almost no genetically encoded tags that enable cellular proteins 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.1808626115
更新日期:2018-12-18 00:00:00
abstract::Although much evidence suggests that the plasma membrane of eukaryotic cells is not homogenous, the precise architecture of this important structure has not been clear. Here we use transmission electron microscopy of plasma membrane sheets and specific probes to show that most or all plasma membrane-associated protein...
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.0609009103
更新日期:2006-12-12 00:00:00
abstract::It is well known that far fewer men than women enroll in tertiary education in the United States and other Western nations. Developed nations vary in the degree to which men are underrepresented, but the Organization for Economic Co-operation and Development (OECD) average lies around 45% male students. We use data fr...
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.2002861117
更新日期:2020-06-23 00:00:00
abstract::Water oxidation by cyanobacteria, algae, and plants is pivotal in oxygenic photosynthesis, the process that powers life on Earth, and is the paradigm for engineering solar fuel-production systems. Each complete reaction cycle of photosynthetic water oxidation requires the removal of four electrons and four protons fro...
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.1206266109
更新日期:2012-10-02 00:00:00
abstract::Tridecaptin A1 (TriA1) is a nonribosomal lipopeptide with selective antimicrobial activity against Gram-negative bacteria. Here we show that TriA1 exerts its bactericidal effect by binding to the bacterial cell-wall precursor lipid II on the inner membrane, disrupting the proton motive force. Biochemical and biophysic...
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.1608623113
更新日期:2016-10-11 00:00:00
abstract::Our understanding of the mechanisms of neural circuit assembly is far from complete. Identification of wiring molecules with novel mechanisms of action will provide insights into how complex and heterogeneous neural circuits assemble during development. In the Drosophila olfactory system, 50 classes of olfactory recep...
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.1905832116
更新日期:2019-08-06 00:00:00
abstract::Duplication of the genome during the S phase of the cell cycle does not occur simultaneously; rather, different sequences are replicated at different times. The replication timing of specific sequences can change during development; however, the determinants of this dynamic process are poorly understood. To gain insig...
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.0408170101
更新日期:2004-12-21 00:00:00
abstract::All science has uncertainty. Unless that uncertainty is communicated effectively, decision makers may put too much or too little faith in it. The information that needs to be communicated depends on the decisions that people face. Are they (i) looking for a signal (e.g., whether to evacuate before a hurricane), (ii) 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.1317504111
更新日期:2014-09-16 00:00:00
abstract::An endonucleolytic activity is associated with purified PM(2) bacteriophages. It converts the double-stranded supercoiled PM(2) DNA mostly into the linear form that sediments as a homogenous peak in alkaline sucrose gradients. The same activity is found in intact or detergent-lysed phages. Optimal activity is observed...
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.71.12.4965
更新日期:1974-12-01 00:00:00
abstract::Hereditary hemochromatosis (HH) is a common chronic human genetic disorder whose hallmark is systemic iron overload. Homozygosity for a mutation in the MHC class I heavy chain paralogue gene HFE has been found to be a primary cause of HH. However, many individuals homozygous for the defective allele of HFE do not deve...
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.091088998
更新日期:2001-04-24 00:00:00
abstract::Drosophila Numb is a membrane associated protein of 557 amino acids (aa) that localizes asymmetrically into a cortical crescent in mitotic neural precursor cells and segregates into one of the daughter cells, where it is required for correct cell fate specification. We demonstrate here that asymmetric localization but...
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.94.24.13005
更新日期:1997-11-25 00:00:00
abstract::The human genome is made up of long DNA segments, the isochores, which are compositionally homogeneous and can be subdivided into a small number of families characterized by different G+C levels. Chromosome in situ suppression hybridization (in which excess unlabeled human DNA is added to suppress hybridization of rep...
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.90.24.11929
更新日期:1993-12-15 00:00:00
abstract::The p21 region of human chromosome 9 is thought to contain a gene (MLM) involved in genetic susceptibility to melanoma and a gene or genes that influence progression of certain other tumors. Genomic clones that span a large region in 9p21 surrounding the presumptive tumor suppressor gene(s) have been isolated. A set 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.91.16.7563
更新日期:1994-08-02 00:00:00
abstract::The primary obstacle to producing renewable fuels from lignocellulosic biomass is a plant's recalcitrance to releasing sugars bound in the cell wall. From a sample set of wood cores representing 1,100 individual undomesticated Populus trichocarpa trees, 47 extreme phenotypes were selected across measured lignin conten...
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.1009252108
更新日期:2011-04-12 00:00:00