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RECOGNITION Of EUKARYOTIC INITIATOR TRANSfER-RNA BY AN INITIATION fACTOR AND TRANSfER Of METHIONINE MOIETY INTO PEPTIDE LINKAGE

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BIOCHIMICA ET BIOPHYSICA ACTA 1972年第1期287卷 124-&页

作者： DETTMAN, GL STANLEY, WM Department of Molecular Biology and Biochemistry School of Biological Sciences University of California Irvine Calif. 92664 U.S.A.

A protein factor, obtained from 0.5 M KCl extracts of rabbit reticulocyte ribosomes, forms a GTP-dependent complex with the initiator tRNA from rabbit liver, Met-tRNA Met f . This activity has been purified approx. 125-fold by ion-exchange chromatography upon DEAE-cellulose and hydroxylapatite. Complex formation can be observed by virtue of the complex's elution position from Sephadex G-100 and by its retention on Millipore (nitrocellulose) filters. Complex formation is dependent on the presence of GTP; Met-tRNA Met f and GTP bind to the purified factor in a 1 : 1 ratio. 5′-Guanylylmethylenediphosphonate ( Guo -5′-P 2 CH 2 P ) is 50 % as efficient as GTP, while GDP is unable to substitute for GTP. In the presence of saturating amounts of protein and GTP, complex formation is proportional to the amount of Met-tRNA Met f added. With excess amounts of GTP and Met-tRNA Met f , complex formation is proportional to the protein concentration. Heating a solution of the protein at 75 °C for 15 min destroys 80 % of the Met-tRNA Met f binding capacity. Met-tRNA Met m and Phe-tRNA Phe bind poorly to the protein. The binding of the initiator tRNA to the 40-S ribosomal subunit and to the 80-S ribosome of reticulocytes in the presence of the triplet ApUpG is dependent on the initiation factor. The factor stimulates the in vitro incorporation of methionine from [ 35 S]Met-tRNA Met f into acid-insoluble material using ApUpG(pU) n ( n = 25 ± 5 ) as the messenger. The ternary complex, consisting of [ 35 S]Met-tRNA Met f , GTP and factor, was separated from free GTP and [ 35 S]Met-tRNA Met f by Sephad ex G-100 gel filtration. When this complex is used as the only source of radioactive methionine in an in vitro amino acid incorporation system, the transfer of [ 35 S]methionine into acid-insoluble material using ApUpG(pU) n as the messenger is greatly stimulated as compared to the transfer of methionine from free [ 35 S]Met-tRNA Met f or free [ 35 S]-methionine.

关键词： Guo -5′-P 2 CH 2 P , 5′-guanylylmethylenediphosphonate Met-tRNA Met m , methionyl-tRNA that cannot be formylated by Escherichia coli enzymes Met-tRNA Met f , methionyl-tRNA that can be formylated by E. coli enzymes N- formyl-Met-tRNA Met f , methionyl-tRNA that has been formylated by E. coli enzymes Phe-tRNA Phe , phenylalanyl-tRNA A-site, ribosomal aminoacyl-tRNA binding site P-site, ribosomal peptidyl-tRNA binding site Ef-1, the aminoacyl-tRNA binding elongation factor responsible for binding aminoacyl-tRNA to the A-site

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ANALYSIS Of MUTAGEN SPECIfICITY IN DROSOPHILA-MELANOGASTER

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MUTATION RESEARCH 1972年第4期16卷 363-&页

作者： SHUKLA, PT Institute of Animal Genetics Edinburgh Great Britain

The previously reported difference between the mutational spectra of hydrazine (HZ) and hydroxylamine (HA) was confirmed for one selected locus (miniature) at which hydrazine produces no mutations in treated late larval spermatogonia or premeiotic spermatocytes sampled by 3 days' progeny. The genetically effective dose was measured in most experiments by the production of v mutants, and in a few by the production of sex-linked lethals. In a total of over 37 000 X-chromosomes (16 000 from previous, and over 21 000 from present experiments) treatment with HZ yielded no m mutation, but 90 v mutations. After treatment with genetically equivalent doses of HA, m and v mutations were about equally frequent. The ratio of visible mutations at the v locus to lethals on the X-chromosomes was exceptionally high after either treatment. So was the ratio of m mutations to lethals after treatment with HA. The hypothesis was tested that the lack of mutations to m after treatment with HZ was due to discrimination against a spermatogonium carrying an m mutation in the metabolic environment created by the treatment. Support for this hypothesis came from experiments in which the postulated damaging effect of m could have been wholly or partially suppressed by the presence of a second normal allele. HZ treatment of females or of males carrying a duplication of the m locus on the Y produced four independent mutations to m in 14 000 chromosomes altogether. When sampling of spermatozoa from HZ-treated males without the duplication was carried out 21 days after eclosion, two m mutations were obtained. This suggests that discrimination against m spermatogonia may take the form of delayed development into spermatozoa.

关键词： car , carnation cm , carmine EMS, ethyl methanesulphonate f , forked HA, hydroxylamine HZ, hydrazine M -5, Muller-5 chromosome m , miniature N, normal medium v , vermilion y , yellow

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ACTIONS Of TETRAPHENYLBORON ON ELECTRON fLOW IN PHOTOSYSTEM-II Of ISOLATED CHLOROPLASTS

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BIOCHIMICA ET BIOPHYSICA ACTA 1972年第2期256卷 336-&页

作者： HOMANN, PH Department of Biological Science Florida State University Tallahassee Fa. 32306 U.S.A.

Isolated chloroplasts from pokeweed ( Phytolacca americana ) were used in studies of the actions of tetraphenylboron on photosynthetic electron transport. Any effects on sites which couple electron transport to photophosphorylation, could be eliminated by the use of uncoupled chloroplasts. Very low concentrations of tetraphenylboron were found to strongly inhibit the reoxidation in the dark of the reduced primary acceptor Q in chloroplasts poisoned with 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Apparently, the tetraphenylboron anion has a high affinity to the oxygen evolving reaction complex where it is readily photoxidized. Slightly higher concentrations of tetraphenylboron inhibited steady-state rates of oxygen evolution measurably, and induced rapid and irreversible photodestructions of Photosystem II. System I mediated electron transport was not affected by these photoinhibitory processes. In many respects, the effects were similar to those observed in the presence of desaspidin or carbonylcyanide m -chlorophenylhydrazone. However, much lower concentrations of tetraphenylboron were required, and its actions were more restricted to Photosystem II. These properties may make tetraphenylboron a valuable tool in studies on the reaction mechanism of the oxygen-evolving apparatus.

关键词： CCCP carbonylcyanide m -chlorophenylhydrazone DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea DCIP 2,6-dichlorophenolindophenol EGTA ethylenebis(oxyethylenenitrilo) tetraacetate f o the invariable fluorescence f DCMU the fluorescence emission in the presence of DCMU f red the fluorescence emission in the presence of hydrosulfite HOQNO 2-heptyl-4-hydroxyquinoline- N -oxide Q the primary electron acceptor in Photosystem II, the “quencher”

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CIRCULATION, RESPIRATORY VOLUMES AND TEMPERATURE REGULATION Of PIGEON IN DRY AND HUMID HEAT

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COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY 1972年第NA3期43卷 477-&页

作者： SMITH, RM Department of Anatomy and Physiology Indiana University Bloomington Indiana 47401 USA

1. 1. In an 8 km/hr breeze pigeons survived T a s † of 54·5°C in dry air and 42·5°C at 96% r.h. 2. 2. Blood pressure remained relatively constant in the heat. 3. 3. Relative humidity had no effect on the T b or T a at which the f first began to increase, but thereafter as the f slowly increased r.h. had a marked effect on evaporative cooling. 4. 4. Maximal f 's of 650/min with V T 's of 3–4 ml produced a V E max of 2·4 1/min at a T b of 46°C. This V E max was 23–25 times that during rest. 5. 5. The body plethysmograph, used to monitor respiration, blocked cutaneous evaporation of water which significantly hampered the pigeons' ability to thermoregulate when compared to free-standing controls.

关键词： Pigeon respiration circulation temperature regulation relative humidity comparative and environmental physiology Columba livia T a ambient temperature (dry bulb) °C T b deep body (core) temperature (in this study intra-abdominal) °C r.h. relative humidity per cent V T tidal volume per breath ml B.T.P.S. f respiratory frequency cycles/min V E respiratory minute volume ( V E = f × V T ) ml/min max maximum (i.e. f max = maximum respiratory frequency)

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INITIATION Of PROTEIN-SYNTHESIS - INTERACTION Of METHIONINE SPECIfIC TRANSfER RIBONUCLEIC-ACIDS WITH RABBIT RETICULOCYTE RIBOSOMES

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BIOCHIMICA ET BIOPHYSICA ACTA 1972年第4期262卷 525-&页

作者： CASHION, LM STANLEY, WM KOLB, AJ Department of Molecular Biology and Biochemistry School of Biological Sciences University of California Irvine Calif. 92664 U.S.A.

The binding of Met-tRNA Met m and the initiator tRNA, Met-tRNA Met f , to rabbit reticulocyte ribosomes in the presence of various oligoribonucleotides containing the methionine codon, AUG, was studied in an in vitro system. 1. 1. At low concentrations of Mg 2+ , optimum binding of Met-tRNA Met in response to AUG was observed in the concentration range of 1.5–4 M potassium acetate. 2. 2. Triplet specificity between other aminoacyl-tRNAs and their codons was retained under these ionic conditions. 3. 3. Met-tRNA Met f was shown to have a much higher affinity for ribosomes in response to AUG than Met-tRNA Met m . 4. 4. The binding of Met-tRNA Met f was specific for the 40-S ribosomal subunit. 5. 5. Met-tRNA Met f appeared to set the proper reading frame for the specific binding of a second aminoacyl-tRNA molecule to the 40-S ribosomal subunit.

关键词： Met-tRNA Met methionyl-tRNA Met-tRNA Met f that species of methionyl-tRNA that can be formylated by Escherichia coli extracts Met-tRNA Met m that species of methionyl-tRNA that cannot be formylated by E. coli extracts Phe-tRNA Phe phenylalanyl-tRNA Ser-tRNA Ser seryl-tRNA Asp-tRNA Asp aspartyl-tRNA Val-tRNA Val valyl-tRNA Cys-tRNA Cys cysteinyl-tRNA

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INITIATION Of GLOBIN SYNTHESIS

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fEBS LETTERS 1972年第3期24卷 310-+页

作者： CRYSTAL, RG NIENHUIS, AW SHAfRITZ, DA MERRICK, WC ELSON, NA ANDERSON, Wf LAST, JA LAYCOCK, DG PRICHARD, PM GRAf, H PICCIANO, D Section on Molecular Hematology National Heart and Lung Institute 20014 Bethesda Maryland USA

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STRUCTURE Of INSERTED BACTERIOPHAGE MU-1 DNA AND PHYSICAL MAPPING Of BACTERIAL GENES BY MU-1 DNA INSERTION

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PROCEEDINGS Of THE NATIONAL ACADEMY Of SCIENCES Of THE UNITED STATES Of AMERICA 1972年第10期69卷 2823-&页

作者： HSU, M DAVIDSON, N Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena Calif. 91109

It is shown, by electron microscope observation of the structures of heteroduplexes, that Mu-1 DNA inserted into the bacterial episomes flac and f(8)[1] is collinear with, rather than a circulation permutation of, the DNA of the mature Mu-1 bacteriophage. Observation of the position of the inserted Mu defines a point within the gene that has been inactivated (the lacI gene for flac and a transfer gene in f(8)[1] in these particular instances). These examples illustrate a new, general method for physical gene mapping. The episome with Mu DNA inserted into f(8)[1] [i.e., f(8)[1](Mu)], although derived from a single colony, is heterogeneous in that a self-renatured sample shows a nonhomology loop of length 3.0 kb. This nonhomology loop, which has previously been observed in mature Mu-1 DNA, is due to an inversion.

关键词： electron microscopy episomes f lac E. coli

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The mutagenicity to mammalian cells of pyrimidine nucleoside analogs

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Mutation Research - fundamental and Molecular Mechanisms of Mutagenesis 1972年第1期14卷 130-132页

作者： Huberman, Eliezer Heidelberger, Charles McArdle Laboratory for Cancer Research University of Wisconsin Madison WI 53706 United States

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A mutational assay system using the thymidine kinase locus in mouse lymphoma cells

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Mutation Research - fundamental and Molecular Mechanisms of Mutagenesis 1972年第1期16卷 77-87页

作者： Clive, D. flamm, W.G. Machesko, M.R. Bernheim, N.J. National Institute of Environmental Health Sciences Research Triangle Park NC 27709 P.O. Box 12233 United States

A mutational assay system utilizing the thymidine kinase (TK) locus in L5178Y mouse lymphoma cells is described. The TK locus is believed to be diploid and the 3hree expected phenotypes-denoted as TK^+/+, TK^+/- and TK^-/--have been isolated and characterized. The TK^+/+ and TK^+/- phenotypes are sensitive to 5-bromodeoxyuridine (BUdR) and resistant to THMG (thymidine+hypoxanthine+methotrexate +glycine) while the TK^-/- phenotype is BUdR-resistant and THMG-sensitive. In addition, the thymidine kinase activities of the TK^+/+, TK^+/- and TK^-/- clonal lines are, respectively, 61, 27 and o μμmoles of thymidine phosphorylated per 10⁶ cells per min of incubation. And finally, using BUdR or THMG selection medium, the spontaneous TK^+/- → TK^-/- and TK^-/- → TK^+/- mutation rates are 1.2·10^-7 and 6.4·10^-9 mutations per locus per generation, respectively. In BUdR selection medium concentrations of up to 0.8·10⁵ BUdR-sensitive cells per ml can be plated with no effect on the recovery of BUdR-resistant cells;at least 1·10⁵ THMG-sensitive cells can be plated in THMG selection medium without affecting the recovery of THMG-resistant cells. Background mutant frequencies can be kept at or below 2·10^-7 in TK^+/- cultures. Stimulation of the TK^+/- → TK^-/- forward mutation rate has been effected with X-irradiation, ethyl methanesulfonate (EMS) and hycanthone methanesulfonate. By comparing the observed induced mutation rates with the spontaneous TK^+/- → TK^-/- mutation rate an estimate can be made of the relative mutagenicities of various treatments. Thus, for example, 600 R of X-irradiation stimulated the mutation rate 2500-fold over the spontaneous rate, while 2-h exposures to 10^-2 M EMS or 10^-4 M hycanthone methane

关键词： ATP adenosine-5′-triphosphate BUdR 5-bromodeoxyuridine CM cloning medium EMS ethyl methanesulfonate f 10 fischer's medium containing 10% horse serum HGPRT hypoxanthine-guanine phosphoribosyltransferase THMG thymidine+hypoxanthine+ methotrexate+glycine TK thymidine kinase

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IN-VITRO EXCISION-REPAIR Of ULTRAVIOLET-IRRADIATED TRANSfORMING DNA fROM BACILLUS-SUBTILIS

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PROCEEDINGS Of THE NATIONAL ACADEMY Of SCIENCES Of THE UNITED STATES Of AMERICA 1971年第12期68卷 2967-+页

作者： HEIJNEKER, HL PANNEKOEK, H OOSTERBAAN, RA POUWELS, PH BRON, S ARWERT, f VENEMA, G Medical Biological Laboratory TNO Rijswijk (ZH) The Netherlands Institute of Genetics State University of Groningen Haren P.O. Box 14 The Netherlands

The biological activity of UV-inactivated Bacillus subtilis DNA is partly restored after incubation with a UV-specific endonuclease from Micrococcus lutens in conjunction with DNA polymerase and DNA ligase, both isolated from Escherichia coli. The restored activity is not further increased by photoreactivation. Pyrimidine dimers are specifically liberated when irradiated DNA is exposed to the three enzymes. None of these effects is observed when pancreatic DNase is used instead of UV-specific endonuclease.

关键词： DNA excision DNA ligase gene repair f - strain DNA polymerase

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