abstract：:The earliest measurable parameter that shows density-dependent inhibition is the uptake of [(3)H]deoxyglucose by Balb 3T3 cells. The rate decreases even during the exponential phase of growth and reaches a minimum, about 8- to 10-times lower than maximum, as the culture approaches the saturation density. Cells transfo...

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

authors： Bose SK,Zlotnick BJ

更新日期：1973-08-01 00:00:00

abstract：:Rod-shaped "ghosts" that are free of murein have been isolated from E. coli. The shape of these "ghosts" is maintained by a unit membrane soluble in sodium dodecyl sulfate. Ghosts consist of about 20-30% phospholipid (almost exclusively phosphatidylethanolamine) and 50-60% protein; a large fraction of the remaining ma...

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

authors： Henning U,Rehn K,Hoehn B

更新日期：1973-07-01 00:00:00

abstract：:Examples from various plant and animal groups indicate that there has been a general increase in potential versatility of form, determined by the number and range of independently varying morphogenetic parameters, among taxa appearing at successively younger stages in the fossil record. Taxa or body plans with higher ...

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

authors： Vermeij GJ

更新日期：1973-07-01 00:00:00

abstract：:A graph-theoretic condition is given for the existence of stable solutions to the Volterra-Lotka equations. ...

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

authors： Yorke JA,Anderson WN

更新日期：1973-07-01 00:00:00

abstract：:The spectra of the alpha, beta, and gamma forms of zinc monoarsanilazotyrosine-248 carboxypeptidase A are indistinguishable. At pH 8.2 their crystals are yellow, while their solutions are red, lambda(max) 510 nm. Absorption and circular dichroism-pH titrations of the modified zinc and apoenzymes demonstrate that the a...

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

authors： Johansen JT,Vallee BL

更新日期：1973-07-01 00:00:00

abstract：:An inversion loop seen in heteroduplex mapping of the DNA of mature Mu phage induced from a lysogen is observed also in defective lambda phage carrying one end of Mu. 14% of the DNA of Mu, including this region, designated the G loop, is shown to be to the right of all known genes in the prophage map. The inhomogeneou...

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

authors： Daniell E,Boram W,Abelson J

更新日期：1973-07-01 00:00:00

abstract：:The absorption spectrum of an activesite specific chromophoric acyl enzyme, sturgeon beta-(2-furyl)-acryloyl-glyceraldehyde-3-phosphate dehydrogenase, is reported. This acyl enzyme undergoes all of the catalyzed reactions characteristic of the intermediate of the physiological acyl enzyme, 3-phospho-D-glyceroyl-glycer...

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

authors： Malhotra OP,Bernhard SA

更新日期：1973-07-01 00:00:00

abstract：:1,N(6)-Ethenoadenosine triphosphate (epsilon-ATP) has been found to be inactive as a substrate for firefly luciferase. However, chemically synthesized luciferyl-epsilonAMP is oxidized by luciferase and light is emitted. The color of the light is red in contrast to the normal yellow-green observed with luciferyladenyla...

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

authors： Deluca M,Leonard NJ,Gates BJ,McElroy WD

更新日期：1973-06-01 00:00:00

abstract：:The isolated beta subunit of hemoglobin Kansas has an oxygen affinity that is as low relative to the oxygen affinity of the beta(A) subunit as the affinity of hemoglobin Kansas is low relative to hemoglobin A. Thus the low affinity properties of hemoglobin Kansas are almost completely reflected in the properties of th...

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

authors： Riggs A,Gibson QH

更新日期：1973-06-01 00:00:00

abstract：:Neurons in the cochlear nuclei of duck embryos become responsive to tonal stimuli in an orderly spatial and temporal sequence. Cells responding to lower frequencies are recorded before those responding to higher frequencies. Auditory neurons are spatially arranged according to their characteristic frequencies, indicat...

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

authors： Konishi M

更新日期：1973-06-01 00:00:00

abstract：:The kinetics of the reduction of horseheart ferricytochrome c by sodium dithionite (phosphate buffer-sodium chloride; pH 6.5, mu = 1.0, 25 degrees ) features two reaction pathways; one with the rate constant k(3) = 1.17 x 10(4) M(-1) sec(-1), the other with the rate constant k(1)k(2)/k(-1) = 6.0 x 10(4) M(-1) sec(-1)....

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

authors： Creutz C,Sutin N

更新日期：1973-06-01 00:00:00

abstract：:A new common cell-surface antigen associated with murine and feline C-type RNA leukemia viruses was demonstrated by the use of rabbit antiserum against feline leukemia virus and the indirect membrane immunofluorescence test. Common cell-surface antigen was found in all leukemias of all strains of mice tested, in norma...

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

authors： Yoshiki T,Mellors RC,Hardy WD Jr

更新日期：1973-06-01 00:00:00

abstract：:Chick-limb mesodermal cells have been maintained in tissue culture under conditions that permit development of muscle and cartilage. 3-Acetylpyridine, a nicotinamide-antagonized muscle teratogen, potentiates chondrogenic expression in cell cultures, as evidenced by histological and biochemical criteria, including the ...

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

authors： Caplan AI,Stoolmiller AC

更新日期：1973-06-01 00:00:00

abstract：:The saturation values for ribosomal RNA hybridization have been determined for DNA from diploid and polytene tissues of Drosophila melanogaster. These values have been measured in XO and XX larvae which have, respectively, one and two nucleolus organizers in the diploid chromosome set. The results show that (1) in dip...

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

authors： Spear BB,Gall JG

更新日期：1973-05-01 00:00:00

abstract：:The reactivities of N-iodosuccinimide and iodine with various goitrogenic compounds were studied with dimethylsulfoxide through which nitrogen had been bubbled as a solvent. Although iodine does not react with all of the compounds, N-iodosuccinimide does react with all of them. N-Iodosuccinimide may, therefore, serve ...

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

authors： Jirousek L,Soodak M

更新日期：1973-05-01 00:00:00

abstract：:Fast axoplasmic transport was studied in dorsal root ganglion cells of the cat. Proteins carried in the fast axoplasmic flow were labeled after an intraganglionic injection of (L)-[4,5-(3)H]leucine. The rate of transport was 380 +/- 26 mm/day in both the central and peripheral branches of the bifurcating axons that ar...

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

authors： Anderson LE,McClure WO

更新日期：1973-05-01 00:00:00

abstract：:We analyzed the relationship of genetic factors determining the expression of endogenous type-C RNA tumor viruses and other host-gene markers to tumorigenesis. A hybridization experiment was performed with mice of strains AKR/J and C57L, the first filial (F(1)) generation hybrids, the second filial (F(2)) generation h...

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

authors： Meier H,Taylor BA,Cherry M,Buebner RJ

更新日期：1973-05-01 00:00:00

abstract：:Rifamycin antibiotics, which inhibit RNA-directed DNA polymerase of Rauscher leuckemia virus, prevent the leukemogenic activity of the virus, and the effect of leukemogenesis correlates with the magnitude of inhibition of the purified enzyme. This inhibition of enzyme activity by rifamycin SV derivatives is due to a r...

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

authors： Wu AM,Ting RC,Gallo RC

更新日期：1973-05-01 00:00:00

abstract：:Cell membrane proteins synthesized after infection of Escherichia coli B with wild-type phage T4 and rIIA mutants were analyzed by dodecyl sulfate-polyacrylamide gel electrophoresis. A protein with an approximate molecular weight of 74,000 is present in membranes isolated from T4r(+)-infected cells, but is not found i...

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

authors： Ennis HL,Kievitt KD

更新日期：1973-05-01 00:00:00

abstract：:Protein Hal is a human gamma4 heavy-chain disease protein whose molecular weight is reduced from 55,000 to 25,000 in 6 M guanidine due to the lack of disulfide bonds between heavy chains. Studies of aminoacid sequence indicate that it contains a gap of about 240 residues, starting 10 residues from the N-terminal end a...

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

authors： Frangione B,Lee L,Haber E,Bloch KJ

更新日期：1973-04-01 00:00:00

abstract：:Inhibition of protein synthesis in rabbit reticulocyte lysates by double-stranded RNA is caused by the inactivation of IF-3, an initiation factor required for the recycling of ribosomes and for their binding to messenger RNA. The evidence for this is that (i) the inhibition can be overcome by addition of exogenous If-...

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

authors： Kaempfer R,Kaufman J

更新日期：1973-04-01 00:00:00

abstract：:Cell aggregation in Dictyostelium discoideum appears to involve the production and detection of 3':5'-cyclic AMP. Two pertinent catalytic activities have been studied in concentrates from D. discoideum purified 50- to 100-fold. They are (i) adenylate cyclase and (ii) ATP pyrophosphohydrolase. ATP pyrophosphohydrolase ...

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

authors： Rossomando EF,Sussman M

更新日期：1973-04-01 00:00:00

abstract：:The enzymes responsible for the oxidation of n-octane to octanoic acid or beyond in Pseudomonas oleovorans are octane inducible and are coded by genes borne on a transmissible extrachromosomal element. The octane to octanoate enzymes induced by octane are repressed by octanol. The chromosome also carries genes coding ...

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

authors： Chakrabarty AM,Chou G,Gunsalus IC

更新日期：1973-04-01 00:00:00

abstract：:Messenger RNA from rat liver was partially purified by chromatography on cellulose on the basis of its poly(A) content. Microgram amounts of this RNA stimulate protein synthesis manyfold in a heterologous cell-free system, derived from Krebs ascites cells supplemented with reticulocyte initiation factors. The messenge...

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

authors： Schutz G,Beato M,Feigelson P

更新日期：1973-04-01 00:00:00

abstract：:The reactions catalyzed by Mo enzymes each find the product differing from the substrate by two electrons and two protons (or some multiple thereof). The coordination chemistry of Mo suggests that there is a distinct relationship between acid-base and redox properties of Mo complexes, and that a coupled electron-proto...

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

authors： Stiefel EI

更新日期：1973-04-01 00:00:00

abstract：:A solid-phase immunoadsorbent capable of binding mouse interferon has been prepared. Starting from crude tissue-culture material, interferon could be purified 1990 times in a single step of affinity chromatography. Overall recovery ranged from 55 to 103% with tissue culture and mouse-brain interferon; however, only 5%...

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

authors： Sipe JD,de Maeyer-Guignard J,Fauconnier B,de Maeyer E

更新日期：1973-04-01 00:00:00

abstract：:Highly purified globin mRNA from ducks was copied with RNA-directed DNA polymerase from avian myeloblastosis virus into anti-messenger DNA. With excess RNA, more than 90% of this DNA annealed back to its template with a C(o)t/2 value of 7.5 x 10(-4) mol.sec. liter(-1); the melting temperature of the hybrid was 86 degr...

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

authors： Imaizumi T,Diggelmann H,Scherrer K

更新日期：1973-04-01 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：:30S ribosomal proteins from Bacillus stearothermophilus (B. proteins) have been fractionated and characterized with respect to their ability to replace various E. coli 30S proteins (E. proteins) in the E. coli 30S ribosome reconstitution system. The functional counterparts of all the E. proteins, except S1, S6, S9, an...

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

authors： Higo K,Held W,Kahan L,Nomura M

更新日期：1973-03-01 00:00:00

abstract：:Let E and F be vector bundles and D:E --> F an operator of order k. We associate a sequence of invariants ((l))(D), l >/= 0 with D which generalize the concept of curvature in a natural way. In the case where D = D(theta) is the differential operator of a connection theta on a vector bundle E, ((1))(D(theta)) is the c...

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

authors： Knapp RE

更新日期：1973-03-01 00:00:00

abstract：:An interpretation is given of recent experiments by Brunori et al. on the binding of carbon monoxide by hemoglobin under photodissociating conditions. It is shown that their results follow directly from scalable models for hemoglobin in which the protein-modulated interactions are separable from the ligand binding. ...

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

authors： Szabo A,Karplus M

更新日期：1973-03-01 00:00:00

abstract：:Microtubule assembly is enhanced by the addition of 1 M sucrose or 4 M glycerol to the reassembly mixture. Tubulin can be purified from guinea pig brain readily and in good yield by two cycles of assembly in glycerol-containing solutions. The tubules assembled in glycerol and sucrose are more stable than tubules forme...

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

authors： Shelanski ML,Gaskin F,Cantor CR

更新日期：1973-03-01 00:00:00

abstract：:The electromechanochemical model has been reformulated to take account of the close connection between energy coupling and catalysis. In catalysis the protein is programmed to utilize thermal energy to produce local strains in the catalytic cavity and to generate conformational states that favor substrate --> product ...

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

authors： Green DE,Ji S

更新日期：1973-03-01 00:00:00

abstract：:In a culture medium of pH 7.4 and a folic acid concentration of 100 mug/liter that contains 5% heat-inactivated chicken plasma rather than serum, the rate of proliferation of normal chicken fibroblasts is determined by the concentration of calcium. Proliferation, rapid when the calcium concentration is physiological, ...

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

authors： Balk SD,Whitfield JF,Youdale T,Braun AC

更新日期：1973-03-01 00:00:00

abstract：:Earlier papers demonstrated an extensive genetic exchange among fluorescent Pseudomonads; this one documents for genes specifying enzymes of peripheral dissimilation an extrachromosomal array, segregation, and frequent interstrain transfer. An hypothesis is presented of a general mechanism for the formation and mainte...

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

authors： Rheinwald JG,Chakrabarty AM,Gunsalus IC

更新日期：1973-03-01 00:00:00

abstract：:Burkitt's lymphomas, linked by previous studies with the DNA-containing Epstein-Barr virus, contain an RNA related in sequence to that of Rauscher leukemia virus. The present study establishes that the viral-related RNA found in Burkitt's tumors is a 70S component encapsulated with RNA-instructed DNA polymerase in a p...

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

authors： Kufe D,Magrath IT,Ziegler JL,Spiegelman S

更新日期：1973-03-01 00:00:00

abstract：:The leading terms in the energy of a general substituted ethane are derived in explicit form as a function of the torsional angle theta, the substituent electronegativities, and their mutual overlaps. The energy is found to be the sum of all four overlaps between pairs of asymmetry orbitals, and satisfies the requisit...

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

authors： Salem L,Hoffmann R,Otto P

更新日期：1973-02-01 00:00:00

abstract：:Seasonal variations in the properties of rabbit-liver fructose 1,6-bisphosphatase have now been linked to corresponding changes in the levels of proteolytic activity in the liver extracts. Incubation of native fructose 1,6-bisphosphatase with purified liver lysosomes causes a 3-fold increase in catalytic activity at p...

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

authors： Pontremoli S,Melloni E,Balestrero F,Franzi AT,De Flora A,Horecker BL

更新日期：1973-02-01 00:00:00

abstract：:Adenosine 3':5'-cyclic monophosphate added to exponentially growing cells of Hemophilus influenzae strain Rd increases competence for transformation 100- to 10,000-fold. Cyclic AMP added to near-stationary or stationary cells does not increase competence over the high level normally found in the early stationary phase...

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

authors： Wise EM Jr,Alexander SP,Powers M

更新日期：1973-02-01 00:00:00

abstract：:A heterogeneous RNA fraction with properties resembling those of messenger RNA was identified in mammalian mitochondria. Synthesis of contaminating RNA of nuclear origin was suppressed by treatment with camptothecin. Labeling of the messenger-like RNA is completely inhibited by ethidium bromide, a specific inhibitor o...

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

authors： Perlman S,Abelson HT,Penman S

更新日期：1973-02-01 00:00:00