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

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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The greening of etiolated bean leaves I. The initial photoconversion process

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BBA - Bioenergetics 1971年第1期226卷 113-127页

作者： Thorne, S.W. Australia

1. During the early stages of the initial photoconversion of the etiolated leaf at 20°, a dark stable intermediate photoproduct appears with a fluorescence peak at 674 nm at 77°K. 2. With E the excitation and f the emission peaks at 77°K, the sequence of fluorescence at photoconversion is protochlorophyllide (E650, f655) →I Intermediate (E668, f674) →II chlorophyllide (E678, f687) →III chlorophyllide (E682, f694) →IV chlorophyll (E672, f680). Shifts I and II are photoactivated, whilst Shifts III and IV occur in the dark and correspond to those described by absorption spectroscopy. 3. Protochlorophyllide is present in the leaf in molecular groups, and spectra show that at fractional (approx. 10%), partial (approx. 40%) or full photoconversion the same sequence of fluorescence is observed. Excitation spectra show that energy absorbed by protochlorophyllide is transferred to each of the forms of chlorophyll in the sequence with almost identical efficiency, indicating that transposition or diffusion of chlorophyll away from the protochlorophyllide complex is not the cause of the dark Shifts III or IV. Energy transfer to chlorophyll f680 after fractional or partial photoconversion does however cease after a long dark time at 20°. 4. from the appearance of the intermediate f674, it is determined that a fundamental group size of protochlorophyllide in vivo is of the order 20 molecules. 5. The intermediate f674 gives chlorophyll a after dark ethanol extraction from the leaf. The photoconversion rate for the intermediate f674 is however twice the rate for chlorophyllide f687, suggesting that photoconversion is a two-step, two-photon process in vivo. © 1971.

关键词： peak wavelengths stated in nm the method of measurement being indicated by the prefix A for absorbance E for fluorescence excitation and f for fluorescence emission

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IMMUNOCHEMICAL COMPARISONS Of 3 AVIAN OVALBUMINS

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COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY 1971年第3B期38卷 513-+页

作者： WEINTRAUB, MS SCHLAMOWITZ, M Department of Biochemistry The University of Texas M.D. Anderson Hospital and Tumor Institute at Houston Houston Texas 77025 USA

1. 1. Schematic immunochemical models of chicken, turkey and duck ovalbumins have been constructed from data obtained from reactions with goat IgG antibodies to chicken and turkey ovalbumins. 2. 2. Chicken and turkey ovalbumins each have an f -valence of 6, 5 being common to both and 4 or 5 are common to duck ovalbumin. 3. 3. The phylogenetic relationship implicit in these results is consistent with taxonomic classification.

关键词： Ovalbumins avian chicken turkey duck immunodiffusion precipitin reactions f -Valence schematic immunologic models phylogeny Gallus domesticus Meleagris gallopavo Anas platyrhynochos domesticus

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ELECTROMAGNETIC THEORY Of HETEROSTRUCTURE INJECTION LASERS

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SOLID-STATE ELECTRONICS 1971年第9期14卷 865-+页

作者： ADAMS, MJ CROSS, M Department of Applied Mathematics and Mathematical Physics University College Cardiff Wales

A theoretical study has been made of the wave-guiding properties of GaAs-Al x Ga 1−x As heterostructure injection lasers. The electromagnetic field distributions and far-field radiation patterns of these devices have been calculated by solving Maxwell's equations for a three-layer wave-guide with complex dielectric constants in each region. The theory also yields threshold currents and external quantum efficiencies as functions of the principal laser parameters—temperature, doping, alloy composition x in the Al x Ga 1−x As regions, active region thickness, and cavity length. This permits detailed comparison of the theoretical results with experiment, and hence further estimates of optimal laser structures. In particular the variation of laser threshold with active region thickness (and the existence of an optimum thickness) in single heterostructures is sucessfully accounted for by the theory. for double heterostructures with the same alloy composition in each passive region, there exists no optimum active region thickness, and hence the lowest thresholds can be obtained by making these structures as thin as possible. Une étude théorique a été menée des propriétés de guide d'ondes de lasers d'injection à hétérostructure GaAs-Al x Ga 1−x As. Les distributions de champ électromagnétique et les dessins de radiation loin du champ de ces dispositifs ont été calculés en résolvant les équations de Maxwell pour un guide d'onde à trois couches avec des constantes diélectriques complexes dans chaque région. La théorie fournit également les courants de seuil et les efficacités quantiques externes en fonction des paramètres principaux du laser—température, doping, composition de l'alliage x dans les régions Al x Ga 1−x As. épaisseur de la région active et longueur de la cavité. Ceci permet une comparaison détaillée des résultats théoriques avec l'expérience, et ainsi des évaluations supplémentaires de structures optimales de lasers. En particulier la théorie explique avec succè

关键词： c velocity of light E photon energy E Geff effective energy gap in the active region G Gn energy gap in the n -type region G Gp energy gap in the p -type region E m photon energy corresponding to the peak of the stimulated emession rate E o band tail parameter for the absorption coefficient E o band tail parameter for the absorption coefficient E on energy gap in the n -type region E op energy gap in the p -type region C i electric field in region i f n fermi-level measured relative to the band edge for n -type material f p fermi-level measured relative to the band edge for p -type material h Planck' constant divided by 2π H i magnetic field in region i j th threshold current density K Bolzmann's constant L cavity length M integer characterising the longitudinal model number in the cavity m c effective mass of the electrons in the conduction band m v effective mass of the holes in the valence band n concentration of electrons in the conduction band N integer characterising the transverse mode numberin the cavity N A concentration of acceptors in the p -type region N D concentration of acceptors in the n -type region p concentration of holdes in the valence band p i complex propagation constant in the x -direction for the electronmagnetic field in the region i q complex propagation constant in the z -direction of the electromagnetic field R reflectivity of the mirrors at the cavity ends t active region thinckness T temperature x aluminium conent α effective absorption term in the active region, accouting for diffraction loss, free carrier absorption and any other mechanism which may be present α′ diffraction loss α′ t.c. free carrier absorption coefficient α i absorption coefficient in region i ε i complex dielectric constant in region i η degree of asymmetry η ext external quantum efficiency η i internal quantum efficiency θ angle in the x−z plane between the direction of the obseration and the normal to the radiating surface ε i refractive index in region i σ n capture cross-section for free carrier absorption b

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REQUIREMENT fOR GTP IN INITIATION PROCESS ON RETICULOCYTE RIBOSOMES AND RIBOSOMAL SUBUNITS

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PROCEEDINGS Of THE NATIONAL ACADEMY Of SCIENCES Of THE UNITED STATES Of AMERICA 1971年第9期68卷 2246-&页

作者： SHAfRITZ, DA LAYCOCK, DG CRYSTAL, RG ANDERSON, Wf Section on Molecular Hematology National Heart and Lung Institute National Institutes of Health Bethesda Maryland 20014

The requirement for GTP in the initiation process on reticulocyte ribosomes and ribosomal subunits has been examined by studying Met-tRNA(f) binding, ribosome-dependent [gamma-(32)P]GTP hydrolysis, and peptide-bond formation with puromycin. Met-tRNA(f) binding can be obtained with the methylene analogue, 5'-guanylylmethylene diphosphonate, as well as GTP, and it is not inhibited by fusidic acid or several other inhibitors of protein synthesis. This reaction can be performed with the 40S subunit and has the same requirements as the Met-tRNA(f)-binding reaction with washed ribosomes. Ribosome-dependent [gamma-(32)P]GTP hydrolysis can be obtained with the initiation factor M(2A) using either washed ribosomes or the 40S subunit. This reaction is also not significantly inhibited by fusidic acid. Peptide-bond formation between puromycin and Met-tRNA(f), however, is inhibited by fusidic acid, and does not occur if the methylene analogue of GTP is substituted for GTP. These data suggest that the binding of the initiator tRNA to the 40S subunit does not require the hydrolysis of GTP, but that at least one GTP hydrolysis event must occur after Met-tRNA(f) binding in order for the first peptide bond to be formed.

关键词： GDPCP Met-tRNA f initiation factors elongation factors fusidic acid

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ACTIONS Of CARBONYLCYANIDE META-CHLOROPHENYLHYDRAZONE ON ELECTRON TRANSPORT AND fLUORESCENCE Of ISOLATED CHLOROPLASTS

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BIOCHIMICA ET BIOPHYSICA ACTA 1971年第1期245卷 129-&页

作者： HOMANN, PH Department of Biological Science Florida State University Tallahassee Fla. 32 306 U.S.A.

The actions of carbonylcyanide m -chlorophenylhydrazone (CCCP) on photosynthetic electron transport and fluorescence have been studied using isolated pokeweed ( Phytolacca americana ) chloroplasts which often had been uncoupled by EDTA washing or by addition of methylamine. The presence of CCCP markedly enhanced the photoreduction of oxygen by System 1 with or without added electron donors. It is concluded that the decreased steady state level of chloroplast fluorescence after an addition of CCCP was largely due to an increased rate of electron flow through System 1 to oxygen, rather than to an inhibition of System 2. The inhibition of oxygen evolution by moderate amounts of CCCP was only slight initially, but became more severe during illumination. CCCP appeared to divert oxidizing equivalents from System 2 into destructive side reactions. CCCP strongly inhibited the reoxidation of the reduced primary acceptor Q in 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU)-poisoned chloroplasts. A comparative study of similar actions by various electron donors to System 2, and by inhibitors of phosphorylation, failed to reveal a simple mechanism. One has to take into account not only a direct reduction of the oxidized reaction partner of Q − by the added agent, but also its effect on the membrane integrity, and on the interactions between the electron carriers in System 2.

关键词： CCCP carbonylcyanide m -chlorophenylhydrazone DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea DCIP 2,6-dichlorophenolindophenol TMPD N , N , N ′, N ″-tetramethyl- p -phenylenediamine Q “quencher”, the primary electron acceptor of System 2 f 0 the invariable fluorescence yield f DCMU the fluorescence yield in the presence of 10 μM DCMU

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The greening of etiolated bean leaves II. Secondary and further photoconversion processes

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BBA - Bioenergetics 1971年第1期226卷 128-134页

作者： Thorne, S.W. Australia

1. Photoconversions in light-dark stages in etiolated bean leaves show that protochlorophyllide is resynthesized to the same level at each stage. 2. Photoconversions 2 and 3 follow the initial photoconversion process, but after Shift IV, chlorophyll (E674, f683) is formed. 3. At fractional or partial Photoconversions 2 or 3, protochlorophyllide transfers energy to chlorophyllides f687 and f694 but not to chlorophyll (E674, f683). 4. Resynthesized protochlorophyllide exists in discrete groups similar to the initial protochlorophyllide, with molecular transposition from these groups taking place at the shift to chlorophyll (E674, f683). © 1971.

关键词： peak wavelengths stated in nm the method of measurement being indicated by the prefix A for absorbance E for fluorescence excitation and f for fluorescence emission

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