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  • gene expression  (49)
  • kinetics
  • Springer  (85)
  • Institute of Physics
  • 1990-1994  (85)
  • 1940-1944
  • 1993  (85)
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Keywords
Publisher
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  • 1990-1994  (85)
  • 1940-1944
Year
  • 1
    Electronic Resource
    Electronic Resource
    A method to determine the relative value of the barriers of carbon chain growth and termination in Fischer-Tropsch synthesis: elementary reaction kinetics for chain growth (1993)
    Springer
    Catalysis letters 19 (1993), S. 93-97 
    Details
    ISSN: 1572-879X
    Keywords: Fischer-Tropsch synthesis ; reaction activation barrier ; carbon chain growth and termination ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A method is established, by which the difference of the reaction activation barriers of carbon chain growth and termination in Fischer-Tropsch (FT) synthesis can be determined from experiments. A FT synthesis is carried out on Fe/Zn catalyst. We apply the method to analyze the experimental result and obtain the difference of reaction activation barriers of carbon chain growth and termination of α-olefins on the catalyst.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00765205
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  • 2
    Electronic Resource
    Electronic Resource
    Butyrate-induced reactivation of the fetal globin genes: A molecular treatment for theβ-hemoglobinophaties (1993)
    Springer
    Cellular and molecular life sciences 49 (1993), S. 133-137 
    Details
    ISSN: 1420-9071
    Keywords: Fetal hemoglobin ; sickle cell anemia ; β thalassemia ; butyrate ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The inherited β-hemoglobinopathies (sickle cell disease and β thalassemia) are the result of a mutation in the adult (β) globin gene. The fetal globin chain, encoded by the γ globin genes, can substitute for the mutated or defective β globin chain, but expression of the γ globin gene is developmentally inactivated prior to birth. Reinducing expression of the normal fetal globin genes is a preferred method of ameliorating sickle cell disease and the β thalassemias. Stimulation of as little as 4–8% fetal globin synthesis in the bone marrow can produce 〉20% fetal hemoglobin in the peripheral circulation, due to enhanced survival of red blood cells containing both sickle and fetal hemoglobin, compared to those containing sickle hemoglobin alone. Butyric acid and butyrate derivatives are generally safe compounds which induce fetal hemoglobin production by stimulating the promoter of the fetal globin genes. An initial trial with the parent compound, delivered as Arginine Butyrate, has demonstrated rapid stimulation of fetal globin expression to levels that have been shown to ameliorate these conditions. Phase 1 trials of an oral butyrate derivative with a long plasma half-life have just begun. These agents now provide a specific new apporach for ameliorating these classic molecular disorders and merit further investigation in larger patient populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01989417
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  • 3
    Electronic Resource
    Electronic Resource
    The polymerization of sickle hemoglobin in solutions and cells (1993)
    Springer
    Cellular and molecular life sciences 49 (1993), S. 110-117 
    Details
    ISSN: 1420-9071
    Keywords: Polymerization ; sickle hemoglobin ; sickle cell disease ; kinetics ; thermodynamics ; polymer domains ; nucleation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The polymerization of sickle hemoglobin occurs by the same mechanisms in solutions and in cells, and involves the formation of 14 stranded fibers from hemoglobin molecules which have assumed a deoxy quaternary structure. The fibers form via two types of highly concentration-dependent nucleation processes: homogeneous nucleation in solutions with hemoglobin activity above a critical activity, and heterogeneous nucleation in similarly supersaturated solutions which also contain hemoglobin polymers. The latter pathway is dominant, and creates polymer arrays called domains. The individual polymers bend, but also cross-link, and the resulting mass behaves as a solid. The concentration of polymerized hemoglobin increases exponentially unless clamped by rate limiting effects such as oxygen delivery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01989414
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  • 4
    Electronic Resource
    Electronic Resource
    Altered proteoglycan gene expression and the tumor stroma (1993)
    Springer
    Cellular and molecular life sciences 49 (1993), S. 447-455 
    Details
    ISSN: 1420-9071
    Keywords: Proteoglycan ; chondroitin sulfate ; decorin ; gene expression ; tumor stroma ; DNA methylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Tumor stroma is a specialized form of tissue that is associated with epithelial neoplasms. Recent evidence indicates that significant changes in proteoglycan content occur in the tumor stroma and that these alterations could support tumor progression and invasion as well as tumor growth. Our main hypothesis is that the generation of tumor stroma is under direct control of the neoplastic cells and that, via a feedback loop, altered proteoglycan gene expression would influence the behavior of tumor cells. In this review, we will focus primarily on the work from our laboratory related to the altered expression of chondroitin sulfate proteoglycan and its role in tumor development and progression. The connective tissue stroma of human colon cancer is enriched in chondroitin sulfate and the stromal cell elements, primarily colon fibroblasts and smooth muscle cells, are responsible for this biosynthetic increase. These changes can be reproduced in vitro by using either tumor metabolites or co-cultures of human colon carcinoma cells and colon mesenchymal cells. The levels of decorin, a leucine-rich proteoglycan involved in the regulation of matrix assembly and cell proliferation, are markedly elevated in the stroma of colon carcinoma. These changes correlate with a marked increase in decorin mRNA levels and a concurrent hypomethylation of decorin gene, a DNA alteration associated with enhanced gene expression. Elucidation of decorin gene structure has revealed an unexpected degree of complexity in the 5′ untranslated region of the gene with two leader exons that are alternatively spliced to the second coding exon. Furthermore, a transforming growth factor beta (TGF-β)-negative element is present in the promoter region of decorin gene. This regulatory domain is likely to be implicated in the silencing of decorin gene by TGF-β and may contribute to the regulation of this matrix gene in the tumor stroma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01923588
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of mineral nutrients on the kinetics of methane utilization by methanotrophs (1993)
    Springer
    Biodegradation 4 (1993), S. 163-170 
    Details
    ISSN: 1572-9729
    Keywords: factorial analysis ; kinetics ; methane ; methanotrophs ; nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of different mineral nutrients on the kinetics of methane biodegradation by a mixed culture of methanotrophic bacteria was studied. The substrate factors examined were ammonia, iron, copper, manganese, phosphate, and sulphide. The presence of iron in the growth medium had a strong effect on the yield coefficient. Yield coefficients up to 0.49 mg protein per mg methane were observed when iron was added at concentrations of 0.10–5.0 mg/l. Iron addition also increased the maximum methane utilization rate. The same effect was observed after addition of ammonium to a medium where nitrate was the only nitrogen source. The observed Monod constant for methane utilization increased with increasing concentration of ammonia. This shows that ammonia is a weak competitive inhibitor as observed by other researchers. Relatively high levels of both ammonia (70 mg/l) and copper (300 µg/l) inhibited the methane degradation, probably due to the toxic effect of copper-amine complexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00695118
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  • 6
    Electronic Resource
    Electronic Resource
    Kinetics of redox cycling of iron coupled with fulvic acid (1993)
    Springer
    Aquatic sciences 55 (1993), S. 103-111 
    Details
    ISSN: 1420-9055
    Keywords: iron(III) (hydr)oxide ; fulvic acid ; iron redox cycling ; dissolution ; surface reactivity ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The kinetics of conversion of iron(III) (hydr)oxides to ferrous iron mediated by fulvic acid have been investigated in order to improve the understanding of the redox cycling of iron at the oxic-anoxic boundary in natural waters. Under the conditions similar to natural waters, fulvic acid is able to reduce the iron(III) (hydr)oxide. The kinetics of the reaction depend on the reactivity of iron(III) (hydr)oxides and the reducing power of the fulvic acid. The rate of reaction is 60 nm/h obtained under following conditions: total concentration of Fe(III) 1.0 × 10−4 M, pH 7.5, fulvic acid 5 mg/L. The rate is considered as a net result of reduction and oxidation in the 〉 FeIII-OH/Fe(II) “wheel” coupled with fulvic acid. In a real natural water system, reductants other than fulvic acid may be of importance. The results obtained in the laboratory, however, provide evidence that the Fe(OH)3(s)/Fe(II) redox couple is able to act as an electron-transfer mediator for the oxidation of natural organic substances, such as fulvic acid by molecular oxygen either in the absence of microorganisms or as a supplement to microbial activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877439
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  • 7
    Electronic Resource
    Electronic Resource
    Bioavailability of controlled release carbamazepine estimated by mixed effect modelling (1993)
    Springer
    European journal of clinical pharmacology 44 (1993), S. 231-235 
    Details
    ISSN: 1432-1041
    Keywords: Carbamazepine ; kinetics ; population pharmacokinetics ; bioavailability ; controlled release ; non-linear model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absorption properties of a conventional tablet of carbamazepine (T) and a controlled release form of carbamazepine (TCR) have been compared using a nonlinear mixed effect model (NONMEM). Plasma carbamazepine concentration data were obtained from an open, steady-state, crossover bioavailability study in which 494 measurements were obtained from 13 patients, with an equal number of samples per patient for each dosage form. The pharmacokinetic model used was a one-compartment open model with first-order absorption and elimination. The objective function was used as a measure of the goodness of fit of the model to the data. Body weight was an important determinant of carbamazepine clearance (CL) but not volume of distribution (V). Accounting for the interindividual variability in volume of distribution did not significantly influence the objective function. Including different rates of absorption (ka) for the two dosage forms resulted in a significant improvement in the objective function, as well as reducing the interindividual variability in the rate of absorption. Adding a parameter for relative bioavailability (f) of TCR improved the objective function statistically, but an unrealistic value for V was obtained, and the absorption and elimination rates appeared to be transposed in the classical “flip-flop” manner. Fixing V to the value obtained before introducing f did not change the objective function and permitted estimation of f without the confounding influence of excessive parameters. The final population parameter estimates (standard error of estimate) were: CL, 0.0522 (0.0019) l·h−1·kg−1; V, 63.7 (FIXED)l; kaT, 0.312 (0.064) h−1; kaTCR, 0.149 (0.016) h−1; f, 1.01 (0.0326); variance (additive) in CL, 0.291 (0.083) (l·h−1·kg−1)2; residual intrasubject error variance (additive), 0.572 (0.082) (mg·l−1)2. The 95% confidence interval of the extent of absorption (f) of 93.6%–107.4% was well within the generally accepted range of ±20%, while the rate of absorption of Tegretol CR was significantly slower than that of Tegretol, as expected for a controlled release product.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00271363
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  • 8
    Electronic Resource
    Electronic Resource
    A new thermobalance for studies of the high-temperature sulphidation of metals and alloys (1993)
    Springer
    Journal of thermal analysis and calorimetry 39 (1993), S. 15-20 
    Details
    ISSN: 1572-8943
    Keywords: alloys ; high-temperature sulphidation ; kinetics ; new thermobalane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird ein neue Apparat zur Untersuchung der Hochtemperatur-Sulfidierung von Metallen in H2/H2S Atmosphare beschrieben. Der Unterschied zwischen diesem Apparat und dem fruher benutzten, besteht im Gasdosierungsystem. Wasserstoff reagiert teilweise mit Schwefel, was eine stabile Zusammensetzung des Gasgemisches beim niedrigen Schwefeldampfdruck sichert. Gewichtsmessungen von Metallen und Legierungen konnen in diesem System bei Temperaturen von 1073 bis 1473 K mit einer Genauigkeit von 10−6 g ausgefuhrt werden.
    Notes: Abstract A new thermogravimetric apparatus for studying the kinetics of metal sulphidation in a H2/H2S gas mixture is described. The main difference between this device and other equipment is the application of hydrogen to obtain a H2/H2S mixture at suitable sulphur partial pressures at a total mixture pressure of 1 atm. The use of the carrier gas allows the measurement of sulphidation kinetics under dynamic conditions and consequently over a much wider pressure range of sulphur vapour, down to 10−12 atm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02235442
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  • 9
    Electronic Resource
    Electronic Resource
    Thermal and temperature dependence of electrical conductivity studies on Zn, Cd and Hg hydrazone complexes (1993)
    Springer
    Journal of thermal analysis and calorimetry 39 (1993), S. 65-74 
    Details
    ISSN: 1572-8943
    Keywords: electrical conductivity ; hydrazone complexes ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Bei zwei verschiedenenpH-Werten wurden die Zn-, Cd- und Hg-Komplexe von Isatinisonicotinoylhydrazon hergestellt. Diese wurden thermisch untersucht (TG, DTG, DTA) und die Gleichstromleitfähigkeit von gepreßten Pulverproben als eine Funktion der Temperatur untersucht. Sowohl für die Liganden als auch für die Komplexe wurden die Aktivierungsenergien (ΔE) berechnet, wobei sich für die Liganden niedrigere Werte ergaben. Man fand, daß die Größe von ΔE durch die Art des Metalles und denpH-Wert bei der Herstellung beeinflußt wird.
    Notes: Abstract The complexes of Zn, Cd and Hg of isatin isonicotinoyl hydrazone were prepared at two differentpHs. Their thermal studies (TG, DTG and DTA) have been made and the DC electrical conductivity of compressed powder samples as a function of temperature was investigated. The activation energies (ΔE) were calculated for the ligand and the complexes which showed that the ligand has a lower value of ΔE than the complexes. The magnitude of ΔE was found to be affected by the nature of the metal and thepH of preparation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02235447
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of alkali additives on the kinetics of WO3+CCl4 reaction (1993)
    Springer
    Journal of thermal analysis and calorimetry 39 (1993), S. 75-86 
    Details
    ISSN: 1572-8943
    Keywords: chlorination ; kinetics ; WO3+CCl4 reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Mittels Thermogravimetrie wurde die Chlorierungskinetik von alkaliversetztem (K und Li) Wolframtrioxid untersucht, wobei CCl4 als Chlorierungsreagens fungierte. Die Reaktivität der modifizierten Proben wurden mit der von reinem WO3 verglichen. Für die reinen und für die alkaliversetzten Proben wurden ähnliche scheinbare Aktivierungsenergien gefunden. Der Zusatz von Kalium verursacht jedoch eine starke Abnahme der ursprünglichen Reaktionsgeschwindigkeit, während oberflächiges Lithium keinen Effekt zeigt. Während der Chlorierung wurde eine ständige Senkung der linearen Reaktionsgeschwindigkeit für beide Proben festgestellt, was mit Rückhalteeffekten von oberflächigen Nebenprodukten und Alkalizusätzen erklärt wird. Zur Beschreibung der isothermen TG-Kurven wurde ein entsprechendes kinetisches Modell angenommen, welches auf einer monoton steigenden Inhibition dieser Proben basiert. Die auf der Grundlage dieses Modelles berechnete Kurve stimmt recht gut mit den experimentellen Ergebnissen überein.
    Notes: Abstract The chlorination kinetics of alkali-added (K and Li) tungsten trioxide were studied by thermogravimetry, using gaseous CCl4 as chlorinating agent. The reactivity of the modified samples was compared to the results on the chlorination of pure WO3. Similar apparent activation energies were found for the pure and alkali-added samples. However, potassium additive resulted in a strong decrease of the initial reaction rate, while surface lithium has no influence on it. During the chlorination a continuous decrease of the linear reaction rate was observed for both samples, which was explained by retarding effects of surface by-products and alkali additives. For describing the isothermal TG curves an appropriate kinetic model, based on the monotonously increasing inhibition of these species was assumed. The curve calculated with this model fits well to the experimental results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02235448
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  • 11
    Electronic Resource
    Electronic Resource
    Comparative studies on the curing kinetics and thermal stability of tetrafunctional epoxy resins using various amines as curing agents (1993)
    Springer
    Journal of thermal analysis and calorimetry 39 (1993), S. 229-238 
    Details
    ISSN: 1572-8943
    Keywords: epoxy resins ; kinetics ; thermal stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Vernetzungsreaktionen der Epoxidharze Tetraglycidyl-diamino-diphenyl-methan (TGDDM) und Tetraglycidyl-methylen-bis(o-toluidin) (TGMBT) unter Verwendung von Diaminodiphenylsulfon (DDS), Diaminodiphenylmethan (DDM) und Diethylentriamin (DETA) als Vernetzungsmittel wurden kinetisch mittels DSC untersucht. Die dynamischen Scans im Temperaturbereich 20°–300°C wurden analysiert, um unter Anwendung einiger empirischer Gleichungen die Aktivierungsenergie und die Reaktionsordnung des Vernetzungsprozesses zu ermitteln. Die Aktivierungsenergie der einzelnen Epoxy-Systeme liegt im Bereich 71.9–110.2 kJ·mol−1. An der ausgehärteten Harze wurde mittels TG in einer statischen Luftatmosphäre un deiner Aufheizgeschwindigkeit von 10 Grad/min die Kinetik des termischen Abbaues untersucht. Man fand, daß die thermiscehn Abbaureaktionen in einem Schritt ablaufen und ihre Aktivierungsenergie im Intervall 27.6–51.4 kJ·mol−1 liegt.
    Notes: Abstract The curing reactions of the epoxy resins tetraglycidyl diaminodiphenyl methane (TGDDM) and tetraglycidyl methylenebis (o-toluidine) (TGMBT) using diaminodiphenyl sulfone (DDS), diaminodiphenyl methane (DDM) and diethylenetriamine (DETA) as curing agents were studied kinetically by differential scanning calorimetry. The dynamic scans in the temperature range 20°–300°C were analyzed to estimate the activation energy and the order of reaction for the curing process using some empirical relations. The activation energy for the various epoxy systems is observed in the range 71.9–110.2 kJ·mol−1. The cured epoxy resins were studied for kinetics of thermal degradation by thermogravimetry in a static air atmosphere at a heating rate of 10 deg·min−1. The thermal degradation reactions were found to proceed in a single step having an activation energy in the range 27.6–51.4 kJ·mol−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01981736
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  • 12
    Electronic Resource
    Electronic Resource
    Gamma-radiation effects on the reduction of hematite to iron in the graphite-iron(III) oxide system (1993)
    Springer
    Journal of thermal analysis and calorimetry 39 (1993), S. 87-95 
    Details
    ISSN: 1572-8943
    Keywords: gamma radiation effects ; graphite-hematite system ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Mittels isothermer und dynamischer TG wurde im Graphit-Eisen(III)oxidsystem in Luft der Einfluß von60Co-Gammastrahlung und von verschiedenen Probenzusammensetzungen auf die Reduktion von Hämatit zu Eisen untersucht. Entsprechend verschiedener theoretischer Modelle heterogener Reaktionen wurde eine kinetische Analyse der isothermen Daten durchgeführt und die Ergebnisse zeigten, daß das dreidimensionale Phasengrenzenmodell die beste Übereinstimmung liefert. Die Analyse der dynamischen TG-Daten wurde mittels der Integralmethode von Ozawa, der Coats-Redfem-Methode und einer zusammengesetzten Methode auf der Grundlage der modifizierten Coats und Redfern Gleichung durchgeführt. Die Aktivierungsparameter wurden berechnet und die Ergebnisse der verschiedenen Methoden miteinander verglichen und diskutiert. Strahlung scheint keine Änderung des Reaktionsmodelles oder des Mechanismus hervorzurufen. Durch Bestrahlung gibt es aber ein Absinken der Aktivierungsenergie und des Frequenzfaktors sowie ein Absinken der Halbwertszeit der Reaktion, was bei höheren Temperaturen und höherer Dosis bemerkenswert groß ist.
    Notes: Abstract The effects of60Co-gamma radiation and of various sample composition on the reduction of hematite to iron in the graphite-iron(III) oxide system in air were studied using isothermal and dynamic TG techniques. Kinetic analysis of isothermal data were performed according to various theoretical models of heterogeneous reactions and the results showed that the three-dimensional phase boundary model gives the best fit of data. Analysis of dynamic TG data were made using Ozawa integral method, Coats-Redfern method and a composite method based on the modified Coats and redfern equation. The activation parameters were calculated and the results of the different methods were compared and discussed. Radiation apparently did not introduce a change in the reaction model or mechanism. However, there is a decrease in activation energy and frequency factor upon irradiation and a decrease in the half-life time of the reaction which is remarkable at the higher temperatures and higher doses.
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    URL: http://dx.doi.org/10.1007/BF02235449
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  • 13
    Electronic Resource
    Electronic Resource
    Isothermal DSC investigation of the kinetics of thermooxidative decomposition of some edible oils (1993)
    Springer
    Journal of thermal analysis and calorimetry 39 (1993), S. 217-220 
    Details
    ISSN: 1572-8943
    Keywords: DSC ; edible oils ; isothermal method ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Unter Einsatz der isothermen Methode wurden kinetische Untersuchungen der thermooxidativen Zersetzung einiger Speiseöle durchgeführt. Zur Bestimmung des Umwandlungsgrades wurde ein DS-Kalorimeter von DuPont eingesetzt. Grundlage der Untersuchung bildeten Leinöl, Rizinusöl und Olivenöl.
    Notes: Abstract The thermooxidative decompositions of some edible oils were investigated. Isothermal measurements of convention were made with a Du Pont differential scanning calorimeter. Linseed oil, castor oil, olive oil and cod-liver oil were investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01981734
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  • 14
    Electronic Resource
    Electronic Resource
    Study on curing of novolac epoxy resin (1993)
    Springer
    Journal of thermal analysis and calorimetry 39 (1993), S. 351-358 
    Details
    ISSN: 1572-8943
    Keywords: epoxy resin ; kinetics ; polyamide hardener
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Mittels DSC wurde die Optimierung des Einsatzverhältnisses von Epoxidnovolackharz Dobeckot E4 und Polyamidhärtungsmittel EH411 durchgeführt. Die Daten ergaben, daß ein Harz-Polyamid-Verhältnis von 100∶40 bzw. 100∶50 das Optimum zu sein scheint, bei dem die Aushärtung am größten ist. Mittels isothermer und dynamischer DSC-Methoden wurden die kinetischen Parameter für diese Ansätze ermittelt. Unter Anwendung der isothermen DSC-Methode im Temperaturbereich 70°–90°C wurde die Geschwindigkeitskonstante für den Aushärtungsprozeß dieser Ansätze ermittelt. Diese wurden mittels Extrapolation der erhaltenen Angaben für höhere Temperaturen auch für die Temperatur 201°C (Raumtemperatur) vorhergesagt. Vorhergesagte und experimentell ermittelte Werte stehen in guter Übereinstimmung zueinander.
    Notes: Abstract The optimization of proportions of novolac epoxy resin, Dobeckot E4 and polyamide hardener, EH411 has been established by DSC and the data indicates that resin-polyamide, 100∶40 and 100∶50, appear to be optimum where ‘extent of cure’ is maximum. The kinetic parameters for these formulations have been evaluated using isothermal and dynamic modes by employing DSC. The rate constants have been evaluated for curing process of these formulations using isothermal DSC mode in the temperature range of 70°–90°C. These have also been predicted at 20°±1°C (room temperature) by extrapolating the data obtained at elevated temperatures. A comparison of the predicted values with the experimental values shows that there is a good agreement between them.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01983533
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  • 15
    Electronic Resource
    Electronic Resource
    The glucocorticoid receptor precludes the binding of a transcriptional repressor protein to the long terminal repeat of the mouse mammary tumor virus (1993)
    Springer
    Molecular and cellular biochemistry 122 (1993), S. 25-37 
    Details
    ISSN: 1573-4919
    Keywords: glucocorticoid receptor ; MMTV ; transcription factors ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The long terminal repeat (LTR) of the mouse mammary tumor virus was used as a template to examine the dual binding parameters of the glucocorticoid-receptor (GR) and a repressor protein termed Inhibitory Factor 1 (IF1). The roceptor binds specifically to the glucocorticoid response element and precludes the binding of IF1 to its juxtaposed binding site within the LTR. When the two DNA targets are separated by the insertion of an additional 52 base pairs, coincident binding of both proteins is observed. Gel retention assays reveal three distinct nucleoprotein complexes. The first complex consists of the receptor and the LTR, the second is comprised of IF1 and DNA and the third is a multiprotein-DNA complex consisting of the GR, IF1 and DNA, migrating at a higher molecular weight position. The inhibition of IF1 binding by the presence of prebound GR leads to the repression of transcription of juxtaposed genes. The GR may act to block access of a sequence, used by the cell to titrate repressor proteins and facilitate the onset of gene expression. (Mol Cell Biochem122: 25–37, 1993)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00925734
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  • 16
    Electronic Resource
    Electronic Resource
    Expression of pregnancy-specific β1-glycoprotein genes in hematopoietic cells (1993)
    Springer
    Molecular and cellular biochemistry 122 (1993), S. 147-158 
    Details
    ISSN: 1573-4919
    Keywords: PSG transcripts ; gene expression ; PCR ; T lymphocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The presence of PSG in blood cells has been demonstrated by immunohistochemical staining. However, the origin of these proteins is not known. This report examines the expression of the PSG genes in different types of freshly isolated blood cells. RNA isolated from bone marrow and peripheral blood cells of healthy individuals was analyzed for PSG transcripts by reverse transcriptase-polymerase chain reaction using synthetic oligonucleotide primers specific for the PSG genes. The level of expression of the PSG genes in different types of cells exhibited significant individual variation. Trace amounts of PSG transcripts could be detected in polymorphonuclear cells (PMN), monocytes and B lymphocytes while T lymphocytes always contained the highest level of transcript. The expression of PSG genes in the blood cells apparently was not affected by the method of isolation nor by overnight culturing of these cells except in the case when lymphocytes were separated by rosetting with sheep red blood cells. All reported PSG transcripts were detected in blood cells. Both type I and type II transcripts of the PSG genes were detected in blood cells with the exception of type II transcript of PSG5 and PSG11 which were only found in the placenta. Tissue specificity in the expression or alternative splicing of some of the PSG family members was implicated.
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    URL: http://dx.doi.org/10.1007/BF01076099
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  • 17
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    Hemoglobins with multiple reactive sulphydryl groups: The reaction of pigeon hemoglobin with 5,5′-dithiobis (2-nitrobenzoic acid) (1993)
    Springer
    The protein journal 12 (1993), S. 639-646 
    Details
    ISSN: 1573-4943
    Keywords: Sulphydryl groups ; multiple ; hemoglobin ; kinetics ; ionizable groups
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Pigeon hemoglobin has eight reactive sulphydryl groups per (tetramer) molecule, as determined by Boyer titration with p-chloromercuribenzoate. However, only four of these are titra-table with 5,5′-dithiobis(2-nitrobenzoate) under the same experimental conditions. The time course of the reaction of pigeon hemoglobin with 5,5′-dithiobis(2-nitrobenzoate) is biphasic. In thepH range 6–9, the fast phase is between one and two orders of magnitude faster than the slow phase. For the fast phase,k app, the apparent second-order rate constant, increases monotonously withpH. Quantitative analysis reveals that the reactionof the sulphydryl group responsible for this phase is coupled to the ionization of two groups with pK a values of 6.15±0.1 and 8.5±0.1. These pK a values are assigned to HisHC3(146)β and to the CysF9(93)β sulphydryl group, respectively. For the slow phase thek app vs.pH profiles are bowl-shaped. Analysis reveals that the reaction of the sulphydryl group to which this phase may be attributed is coupled to the ionization of two groups with mean pK a values of 6.53±0.1 and 8.25±0.1. Examination of the structure of hemoglobin allows us to assign these values to HisG19(117)β and CysB5(23)β, respectively. The CysB5(23)β sulphydryl is in the region of the molecule where amino acid substitutions have been found to give rise to significant changes in the oxygen affinity of hemoglobin [Huanget al. (1990),Biochemistry 29, 7020–7023.
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    URL: http://dx.doi.org/10.1007/BF01025129
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  • 18
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    Expression of an ABA-responsive osmotin-like gene during the induction of freezing tolerance in Solanum commersonii (1993)
    Springer
    Plant molecular biology 21 (1993), S. 729-735 
    Details
    ISSN: 1573-5028
    Keywords: ABA ; cDNA cloning ; freezing tolerance ; gene expression ; osmotin-like protein ; Solanum commersonii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated a cDNA (pA13) of an ABA-responsive gene from suspension cultures of Solanum commersonii. The deduced amino acid sequence of pA13 cDNA revealed 89 and 91% identity with tobacco osmotin and tomato NP24 protein, respectively. The accumulation of the transcript corresponding to pA13 cDNA was regulated by ABA, cold temperature, and low water potential treatments. Cold-induced accumulation of the pA13 transcript was partially suppressed by fluridone, an ABA synthesis inhibitor, and the suppression was restored by exogenous ABA application. The transcript corresponding to pA13 also accumulated in an organ-specific manner in response to ABA or cold treatment.
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    URL: http://dx.doi.org/10.1007/BF00014558
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  • 19
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    Semi-constitutive expression of an Arabidopsis thaliana α-tubulin gene (1993)
    Springer
    Plant molecular biology 21 (1993), S. 937-942 
    Details
    ISSN: 1573-5028
    Keywords: α-tubulin ; Arabidopsis ; β-glucuronidase ; gene expression ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Arabidopsis tissues, the pool of tubulin protein is provided by the expression of multiple α-tubulin and β-tubulin genes. Previous evidence suggested that the TUA2 α-tubulin gene was expressed in all organs of mature plants. We now report a more detailed analysis of TUA2 expression during plant development. Chimeric genes containing TUA2 5′-flanking DNA fused to the β-glucuronidase (GUS) coding region were used to create transgenic Arabidopsis plants. Second-generation progeny of regenerated plants were analyzed by histochemical assay to localize GUS expression. GUS activity was seen throughout plant development and in nearly all tissues. The blue product of GUS activity accumulated to the highest levels in tissues with actively dividing and elongating cells. GUS activity was not detected in a few plant tissues, suggesting that, though widely expressed, the TUA2 promoter is not constitutively active.
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    URL: http://dx.doi.org/10.1007/BF00027126
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  • 20
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    Identification of cis-acting elements involved in the regulation of the pathogenesis-related gene STH-2 in potato (1993)
    Springer
    Plant molecular biology 22 (1993), S. 279-291 
    Details
    ISSN: 1573-5028
    Keywords: wounding ; elicitor ; plant defense ; gene expression ; tuber ; Solanum tuberosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have characterized a genomic clone containing the potato pathogenesis-related genes STH-2 and STH-21. The two genes are found 4 kb apart on the same chromosome and their sequences are highly similar. They present the same transcriptional orientation and are both interrupted by a single intron. A chimaeric gene consisting of 1015 bp of 5′-flanking sequence and part of the first exon of STH-2 fused to the bacterial β-glucuronidase gene was highly-expressed in tubers of transgenic potato plants after wounding and elicitor treatments. The levels of activity observed in these transgenic plants parallel those observed for the accumulation of STH-2 mRNAs under similar conditions. This indicates that cis-acting elements necessary for the proper activation of the gene are present within 1 kb of 5′-flanking sequences. Functional analysis of 5′ deletions of the STH-2/GUS constructs by transient expression in leaf protoplasts revealed the presence of an upstream regulatory sequence between -135 and -52 which contains a TGAC motif, and a possible negative regulatory region between -52 and -28. A factor present in nuclear extracts of wounded potato tubers was found to bind specifically to nucleotides located between -135 to -105, suggesting that this region contains important cis-regulatory elements.
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    URL: http://dx.doi.org/10.1007/BF00014935
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  • 21
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    Treatment of Agrobacterium or leaf disks with 5-azacytidine increases transgene expression in tobacco (1993)
    Springer
    Plant molecular biology 21 (1993), S. 429-435 
    Details
    ISSN: 1573-5028
    Keywords: azacytidine ; DNA methylation ; gene expression ; inactivation ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have studied the effect of the demethylating agent azacytidine (azaC) on expression of a β-glucuronidase (GUS) gene transferred to tobacco leaf disks by Agrobacterium-mediated transformation. In a system where no selection was performed, where shoot formation was partially repressed, and where Agrobacterium does not express the GUS gene, we were able to follow the early events of transient and stable expression. Two days after inoculation, 8% of the cells expressed GUS but this proportion rapidly decreased to near zero in the following week. Treatment of leaf disks with azaC just after transformation retarded this inactivation to some extent, while treatment of Agrobacterium prior to transformation increased the frequency of transient expression. Three weeks after inoculation the number of GUS-expressing cells increased 4- to 6-fold in the leaf disks treated with azaC and in the leaf disks transformed with azaC-treated bacteria, while the control remained low. These data suggest that DNA methylation is involved in transgene inactivation and that a large number of silent but potentially active transgenes become integrated.
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    URL: http://dx.doi.org/10.1007/BF00028801
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  • 22
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    Transient and stable expression ofgusA fusions with rice genes in rice, barley and perennial ryegrass (1993)
    Springer
    Plant molecular biology 22 (1993), S. 1101-1127 
    Details
    ISSN: 1573-5028
    Keywords: transformation ; promoters ; introns ; gene expression ; Oryza sativa ; Hordeum vulgare ; Lolium perenne
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcriptional and translational fusions were made between the reading frame coding for β-D-glucuronidase and sequences of either a constitutively expressed rice gene (GOS2) involved in initiation of translation or a light-inducible rice gene (GOS5). The transient expression of the fusions was studied via particle bombardment of seedling tissues of rice, perennial ryegrass and barley. Furthermore, the results of transient and stable expression were compared for cell suspensions of four rice varieties, one barley variety and one perennial ryegrass variety. TheGOS2-gusA fusions were active in all three monocots studied. Best results were obtained for a construct having both a transcriptional and a translational fusion as well as intron and exon sequences (PORCEHyg). The level of GUS activity was in the range of activities as obtained by the 35S CaMV promoter transcriptionally fused togusA. ThegusA fusion with the light-inducible gene (GOS5) was active in green seedling tissues of all monocots studied. Also a weak expression compared to theGOS2 constructs was found in stably transformed rice callus. ThegusA fusions with the mannopine synthase promoters 1′ and 2′ of the TR-DNA were transiently expressed at lower levels in cell suspensions than PORCEHyg. For stably transformed rice callus the expression of theGOS2-gusA fusion often decreased during prolonged subculture. This decrease in GUS activity and the various GUS-staining phenotypes of transgenic calli are explained by the presence of different cell types in the suspensions used and in the calli. It is presumed that the nature of the cells and their relative contribution in the calli change drastically upon further subculture.
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    URL: http://dx.doi.org/10.1007/BF00028980
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  • 23
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    Circadian and light-regulated expression of nitrate reductase in Arabidopsis (1993)
    Springer
    Plant molecular biology 23 (1993), S. 349-364 
    Details
    ISSN: 1573-5028
    Keywords: circadian regulation ; enzyme activity ; gene expression ; light regulation ; nitrate reductase ; phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of a number of plant genes is regulated by an endogenous circadian clock. We report that the Arabidopsis NIA2 (nitrate reductase) gene shows robust circadian oscillations in mRNA accumulation which persist for at least 5 days in plants that have been grown in a light-dark (LD) cycle and then transferred to continuous light (LL). We further show that NIA2 mRNA accumulation oscillates in a circadian fashion in plants that have been grown in LD and then transferred to continuous darkness (DD). Results from nuclear run-on transcriptional analysis suggest that the oscillations in steady-state levels of NIA2 mRNA abundance are not primarily due to changes in transcription but, instead, reflect post-transcriptional regulation. The circadian oscillations in NIA2 mRNA abundance are paralleled by circadian oscillations in nitrate reductase enzyme activity (NR activity) in Arabidopsis plants that have been grown in LD and then transferred either to DD or to LL. Etiolated Arabidopsis seedlings express neither NIA2 mRNA nor NR activity. However, both NIA2 mRNA accumulation and NR activity are induced by exposure to white light. The inductive effects of light on NIA2 mRNA accumulation are due, at least in part, to a very low fluence phytochrome-mediated response. However, the persistence of circadian oscillations in NIA2 mRNA abundance for at least 5 days in LL demonstrates that the circadian clock is capable of overriding or gating the inductive effects of light on NIA2 mRNA accumulation in Arabidopsis for an extended, continuous period of time.
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    URL: http://dx.doi.org/10.1007/BF00029010
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    Coordinate gene expression of five subclass histones and the putative transcription factors, HBP-1a and HBP-1b, of histone genes in wheat (1993)
    Springer
    Plant molecular biology 23 (1993), S. 429-434 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; germination ; transcription factor ; wheat histone gene ; wheat seedling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of genes encoding five histones (H1, H2A, H2B, H3 and H4) and the putative transcription factors HBP-1a (17) and HBP-1b (c38) was examined during early germination and in various tissues of young wheat seedlings. The steady-state levels of core histone (H2A, H2B, H3 and H4) mRNAs were coordinately cell cycle-dependent and paralleled the rate of DNA synthesis during early germination, whereas the expression pattern of the linker histone (H1) genes differed. The five subclass histone genes were actively expressed in the meristematic tissues of young seedlings. Moreover, H1 genes were expressed in leaves that consist mostly of non-proliferating cells, in which core histone genes showed little expression. Quantitative alterations to the mRNAs of the putative transcription factors HBP-1a (17) and HBP-1b (c38) of wheat histone genes were similar to those of the core histone mRNAs, suggesting that both factors function in the cell cycle-dependent expression of wheat core histone genes.
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    URL: http://dx.doi.org/10.1007/BF00029019
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  • 25
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    Transient and stable expression of gusA fusions with rice genes in rice, barley and perennial ryegrass (1993)
    Springer
    Plant molecular biology 23 (1993), S. 643-669 
    Details
    ISSN: 1573-5028
    Keywords: transformation ; promoters ; introns ; gene expression ; Oryza sativa ; Hordeum vulgare ; Lolium perenne
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcriptional and translational fusions were made between the reading frame coding for β-D-glucuronidase and sequences of either a constitutively expressed rice gene (GOS2) involved in initiation of translation or a light-inducible rice gene (GOS5). The transient expression of the fusions was studied via particle bombardment of seedling tissues of rice, perennial ryegrass and barley. Furthermore, the results of transient and stable expression were compared for cell suspensions of four rice varieties, one barley variety and one perennial ryegrass variety. The GOS2-gusA fusions were active in all three monocots studied. Best results were obtained for a construct having both a transcriptional and a translational fusion as well as intron and exon sequences (PORCEHyg). The level of GUS activity was in the range of activities as obtained by the 35S CaMV promoter transcriptionally fused to gusA. The gusA fusion with the light-inducible gene (GOS5) was active in green seedling tissues of all monocots studied. Also a weak expression compared to the GOS2 constructs was found in stably transformed rice callus. The gusA fusions with the mannopine synthase promoters 1′ and 2′ of the TR-DNA were transiently expressed at lower levels in cell suspensions than PORCEHyg. For stably transformed rice callus the expression of the GOS2-gusA fusion often decreased during prolonged subculture. This decrease in GUS activity and the various GUS-staining phenotypes of transgenic calli are explained by the presence of different cell types in the suspensions used and in the calli. It is presumed that the nature of the cells and their relative contribution in the calli change drastically upon further subculture.
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    URL: http://dx.doi.org/10.1007/BF00021522
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    Molecular analysis and spatial expression pattern of a low-temperature-specific barley gene, blt101 (1993)
    Springer
    Plant molecular biology 23 (1993), S. 871-879 
    Details
    ISSN: 1573-5028
    Keywords: cold ; low temperature ; barley ; gene expression ; cDNA ; shoot meristem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA clone of the previously unreported low-temperature-induced gene blt101 was isolated after a differential screen of a cDNA library prepared from low-temperature (6 °C day/2 °C night) grown barley shoot meristems. Southern blot analysis of barley ditelosomic addition lines was used to assign this single-copy gene to the long arm of chromosome 4. Analysis of steady-state levels of blt101 mRNA showed the induction of this transcript in shoot meristems upon transfer of barley (cv. Igri) plants from control (20 °C/15 °C) to low (6 °C/2 °C) temperature treatment. Further, the high level of this transcript is maintained at low temperatures but is reduced on transfer from low to control temperatures. The gene is not induced by drought or by foliar application of ABA. Analysis of segregating doubled haploid lines shows that there is no specific association of this gene with either spring/winter growth habit or frost hardiness. Examination of the spatial expression pattern revealed ubiquitous expression of blt101 in low-temperature (6 °C/2 °C) grown barley shoot meristems, mature leaves and roots.
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    URL: http://dx.doi.org/10.1007/BF00021541
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  • 27
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    Differential, temporal and spatial expression of genes involved in storage oil and oleosin accumulation in developing rapeseed embryos: implications for the role of oleosins and the mechanisms of oil-body formation (1993)
    Springer
    Plant molecular biology 23 (1993), S. 1015-1027 
    Details
    ISSN: 1573-5028
    Keywords: embryos ; gene expression ; oleosin ; rapeseed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The temporal and spatial expression of oleosin and Δ9-stearoyl-ACP desaturase genes and their products has been examined in developing embryos of rapeseed, Brassica napus L. var. Topas. Expression of oleosin and stearate desaturase genes was measured by in situ hybridisation at five different stages of development ranging from the torpedo stage to a mature-desiccating embryo. The temporal pattern of gene expression varied dramatically between the two classes of gene. Stearate desaturase gene expression was relatively high, even at the torpedo stage, whereas oleosin gene expression was barely detectable at this stage. By the stage of maximum embryo fresh weight, stearate desaturase gene expression had declined considerably while oleosin gene expression was at its height. In contrast to their differential temporal expression, the in situ labelling of both classes of embryo-specific gene showed similar, relatively uniform patterns of spatial expression throughout the embryo sections. Immunogold labelling of ultra-thin sections from radicle tissue with anti-oleosin antibodies showed similar patterns to sections from cotyledon tissue. However, whereas at least three oleosin isoforms were detectable on western blots of homogenates from cotyledons, only one isoform was found in radicles. This suggests that some of the oleosin isoforms may be expressed differentially in the various types of embryo tissue. The differential timing of stearate desaturase and oleosin gene expression was mirrored by similar differences in the timing of the accumulation of their ultimate products, i.e. storage oil and oleosin proteins. Oil-body fractions prepared from young (2.5 mg) embryos contained very little oleosin protein, as examined by SDS-PAGE and western blotting, whereas identically prepared fractions from dry seeds contained over 10% (w/w) oleosin. Dehydration of oil bodies from young embryos resulted in their breakdown and coalescence into large clumps of oil which could not be re-emulsified, even after rehydration. In contrast, the oleosin-rich oil bodies from mature embryos were stable to dehydration and subsequent rehydration. It is suggested that, in developing rapeseed embryos, the accumulation of storage oil and oleosins is not concomitant but that the eventual deposition of oleosins onto the surfaces of storage oil bodies is essential for their stability during seed desiccation.
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    URL: http://dx.doi.org/10.1007/BF00021816
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    Isolation and characterization of pollen-specific maize genes with sequence homology to ragweed allergens and pectate lyases (1993)
    Springer
    Plant molecular biology 23 (1993), S. 1061-1065 
    Details
    ISSN: 1573-5028
    Keywords: allergens ; gene expression ; microsporogenesis ; pectate lyase ; pollen ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA clone (Zm58.1) was isolated by differential screening from a cDNA library made to mature Zea mays pollen, and shown to be pollen-specific by RNA blot analysis. When this partial-length clone was used to probe a genomic library, a similar but distinct pollen-specific genomic clone (68% sequence identity) was isolated (Zm58.2). The putative proteins coded for by these two clones show sequence homology to several flower-expressed gene products from various plant species, including known pollen allergens from short ragweed (Ambrosia artemisiifolia), and to pectate lyases from the plant pathogenic bacteria Erwinia spp. The two genes map to different chromosomes.
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    URL: http://dx.doi.org/10.1007/BF00021820
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  • 29
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    A novel blue light- and abscisic acid-inducible gene of Arabidopsis thaliana encoding an intrinsic membrane protein (1993)
    Springer
    Plant molecular biology 23 (1993), S. 1187-1198 
    Details
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; blue light ; floral induction ; gene expression ; membrane protein ; DNA sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Continuous irradiation with blue light (400–500 nm) induces flower formation in plantlets of Arabidopsis thaliana (C24) while red light (600–700 nm) is ineffective. This observation started a search for genes that are activated by blue light and initiate the morphogenic programme leading to flower formation. Several genes were identified via their cDNAs. From these clone AthH2, with an open reading frame for a hydrophobic 30.5 kDa polypeptide, was selected for further characterization of the corresponding gene. From a genomic library a DNA fragment of about 6.4 kb was isolated, comprising the coding region as well as 5′-upstream and 3′-downstream flanking segments. The coding region is composed of four exons, which specify a polypeptide of 286 amino acids. Several potential regulatory elements were found between position −670 and −1140 including GA and ABA sequence motifs. The latter could account for the observed induction of the AthH2 gene by ABA. Southern blot analysis of Arabidopsis genomic DNA suggests that the AthH2 gene is encoded by a single-copy gene. Hydropathy plots and secondary structure analysis of the putative polypeptide predict six membrane-spanning domains implicating a function as transmembrane channel protein. It displays significant homology with the proteins TR7a of pea (82%) and RD 28 of A. thaliana (68%).
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    URL: http://dx.doi.org/10.1007/BF00042352
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    Different expression of calpain in skeletal muscle of Japanese quail (Coturnix coturnix japonica) lines selected for body weight (1993)
    Springer
    Biochemical genetics 31 (1993), S. 485-495 
    Details
    ISSN: 1573-4927
    Keywords: muscle protein degradation ; calpain ; gene expression ; genetic variation ; Japanese quail
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Calpain activity was determined by western blot analysis of steady-state concentrations ofm-calpain (calpain requiring millimolar Ca2 for activation) and also by northern blot analysis of steady-state concentrations of mRNA encodingm-calpain in three lines of quail: a random-bred control line (RR) and two lines selected for body weight, one for increased body weight (LL) and another for decreased body weight (SS). Them-calpain activities in skeletal muscle were higher in the SS line and lower in the LL line. From western blot analysis, enzyme levels of calpain were almost the same for all three lines. At the level of gene expression, the mRNA concentration encodingm-calpain was higher in the LL and lower in the SS line. These results suggest that the regulation of calpain activity in skeletal muscle is a three-step process, regulation at the transcription level, regulation at the enzyme level, and regulation of the activation of calpain.
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    URL: http://dx.doi.org/10.1007/BF00554075
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    Molecular cloning and characterization of a legumin-like storage protein cDNA of Douglas fir seeds (1993)
    Springer
    Plant molecular biology 21 (1993), S. 709-715 
    Details
    ISSN: 1573-5028
    Keywords: cDNAs ; seed storage proteins ; Pseudotsuga menziesii ; gene expression ; nucleotide sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA library was made from poly(A)+ RNA isolated from developing Douglas fir (Pseudotsuga menziesii) embryo and megagametophytic tissue, and the cDNA clones were identified by immunoscreening with polyclonal antiserum against the crystalloid storage protein complex of Douglas fir. The nucleotide sequence of the longest cDNA insert (DF1) was analysed. The amino acid sequence derived from the DNA sequence verified its identity as a legumin-like storage protein (pseudotsugin) and confirmed that the protein is synthesized as a precursor similar to the 11–12S storage globulins. The transcripts corresponding to cDNA insert DF1 were abundant in the early-to mid-stages of embryogenesis in the diploid embryonic axes as well as in the haploid megagametophytic tissue. The deduced amino acid sequence of pseudotsugin consists of a 29 amino acid N-terminal signal peptide preceding the acidic polypeptide region (286 amino acids) and the subsequent basic polypeptide region (212 amino acids). The site for post-transcriptional cleavage of the precursor polypeptide to make the A and B polypeptides is localized between asparagine −315 and glycine −316 and is highly conserved between angiosperms and gymnosperms. The deduced amino acid sequence for the DF1 cDNA clone reveals that pseudotsugin is rich in arginine, glutamic acid and serine and is low in cysteine, methionine and lysine. Comparison of the deduced amino acid sequence of Douglas fir pseudotsugin shows between 29–38.5% identity with angiosperm species, 63% identity with interior spruce, and 60% identity with eastern white pine.
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    Cis-acting regulatory regions of the soybean seed storage 11S globulin gene and their interactions with seed embryo factors (1993)
    Springer
    Plant molecular biology 21 (1993), S. 973-984 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; Glycine max ; protein-DNA interaction ; seed storage protein gene ; transcriptional regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A 2.2 kb fragment containing the 5′-flanking region of the soybean glycinin A2B1a gene and its successive deletions with a shorter 5′-flanking sequence were fused, in frame, to the β-glucuronidase (GUS) reporter gene. The resultant fusions were introduced into tobacco plants via Agrobacterium tumefaciens. Assays of the GUS activity in seeds of transgenic tobacco showed that the upstream region, −657 to −327 (relative to the transcription initiation site [+1]), of the glycinin gene is required for optimal expression of the transformed gene. Interactions between embryo nuclear factors and DNA fragments covering the downstream region of −326, in which are included the TATA box and legumin boxes, were not apparent. The embryo factors capable of binding specifically to three subregions, −653 to −527, −526 to −422, and −427 to −321, of the upstream regulatory region were detected. Such factors appeared to be organ-specific and could be found solely in developing seeds at the early middle stage of embryogenesis (around 24 days after flowering). Evidence obtained by characterizing the nature of the binding proteins and by gel mobility shift assays established that the same factor does interact with a consensus motif 5′-ATA/TATTTCN-/CTA-3′ which occurs four times in the cis-acting regulatory region between −657 and −327. Moreover, this conserved motif could also be found in the 5′ regulatory region of another glycinin A1aB1b gene. Thus it is likely that the observed interaction between the nuclear factor and the conserved motifs would lead to activation of transcription from the glycinin genes in maturing soybean seeds.
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    URL: http://dx.doi.org/10.1007/BF00023596
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    Expression of the Arabidopsis AtAux2-11 auxin-responsive gene in transgenic plants (1993)
    Springer
    Plant molecular biology 22 (1993), S. 731-749 
    Details
    ISSN: 1573-5028
    Keywords: auxin ; localization ; gene expression ; beta-galactosidase ; Arabidopsis ; auxin-inducible promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Five constructions containing deletions of the promoter from an auxin-inducible gene of Arabidopsis thaliana, AtAux2-11, were fused to the coding region of the reporter gene LacZ, which encodes β-galactosidase, and a polyadenylation 3′-untranslated nopaline synthase sequence from Agrobacterium. These chimeric genes were introduced into Arabidopsis by Agrobacterium tumefaciens-mediated transformation, and expression of the gene was examined by spectrophotometric and histochemical analyses. A 600 bp fragment from the AtAux2-11 promoter conferred histochemical patterns of staining similar to the longest 5′ promoter tested, a 3.0 kb fragment. Localization of AtAux2-11/LacZ activity in the transgenic plants revealed spatial and temporal expression patterns that correlated with tissues and cells undergoing physiological processes modulated by auxin. LacZ activity was expressed in the elongating region of roots, etiolated hypocotyls, and anther filaments. Expression was detected in the vascular cylinder of the root and the vascular tissue, epidermis, and cortex of the hypocotyl, and filament. The AtAux2-11/LacZ gene was preferentially expressed in cells on the elongating side of hypocotyls undergoing gravitropic curvature. Expression of the chimeric gene in the hypocotyls of light-grown seedlings was less than that in etiolated seedling hypcotyls. The AtAux2-11/LacZ gene was active in the root cap, and expression in the root stele increased at sites of lateral root initiation. Staining was evident in cell types that develop lignified cell walls, e.g. trichomes, anther endothecial cells, and especially developing xylem. The chimeric gene was not expressed in primary meristems. While the magnitude of expression increased after application of exogenous auxin (2,4-D), the histochemical localization of AtAux2-11/LacZ remained unchanged. Transgenic plants with a 600 bp promoter construct (−0.6 kb AtAux2-11/LacZ) had higher levels of basal and auxin-inducible expression than plants with a 3.0 kb promoter construct. Transgenic plants with a −500 bp promoter had levels of expression similar to the −3.0 kb construct. The −0.6 kb AtAux2-11/LacZ gene responded maximally to a concentration of 5 × 10−6 to 5 × 10−5 M 2,4-D and was responsive to as little as 5 × 10−8 M. The evidence presented here suggests that this gene may play a role in several auxin-mediated developmental and physiological processes.
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    Down-regulation of two non-homologous endogenous tomato genes with a single chimaeric sense gene construct (1993)
    Springer
    Plant molecular biology 23 (1993), S. 1-9 
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    ISSN: 1573-5028
    Keywords: down-regulation ; gene expression ; polygalacturonase ; pectinesterase ; chimaeric sense gene ; transgenic ; co-suppression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tomatoes (Lycopersicon esculentum Mill cv. Ailsa Craig) were transformed with a gene construct having 244 bp of the 5′ end of a polygalacturonase (PG) cDNA, coding for a 71 amino acid N-terminal extension to the mature protein, fused to 1320 bp of a pectinesterase (PE) cDNA encoding the full sequence of the mature PE protein. This chimaeric gene was inserted in a sense orientation between a CaMV 35S promoter and terminator for constitutive expression. In transformed tomato plants expression of the endogenous PG and PE genes in the fruit was inhibited; there was little or no observable PG and PE mRNA and a substantial reduction in the level of PG and PE enzyme activity. The transgene was expressed in the leaves of the transformed plants as demonstrated by the accumulation of mRNA, but no protein product could be identified. However, no transgene mRNA or protein were observed in the transgenic fruit. This paper represents the first report of the down-regulation of two non-homologous endogenous genes using a single gene construct. A sense gene construct was responsible for these effects. These findings are discussed in relation to possible mechanisms of action of co-suppression.
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    URL: http://dx.doi.org/10.1007/BF00021414
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    The resistance of cowpea seeds to bruchid beetles is not related to levels of cysteine proteinase inhibitors (1993)
    Springer
    Plant molecular biology 23 (1993), S. 215-219 
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    ISSN: 1573-5028
    Keywords: cowpea ; cystatin ; cysteine endoproteinases ; gene expression ; insect resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA encoding a cysteine proteinase inhibitor was isolated from a cDNA library prepared from developing seeds of an insect-resistant line of cowpea. The sequence of the encoded protein was homologous with those of other plant cysteine endoproteinase inhibitors, and with Type 2 cystatins from animals. Southern blot analyses indicated that small gene families were present in both resistant and susceptible lines of cowpea, while northern blot analyses showed similar levels of expression. It is concluded that the levels of expression of the inhibitor do not account for the differences in insect resistance of the two lines.
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    cDNA cloning and characterisation of novel ripening-related mRNAs with altered patterns of accumulation in the ripening inhibitor (rin) tomato ripening mutant (1993)
    Springer
    Plant molecular biology 23 (1993), S. 193-207 
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    ISSN: 1573-5028
    Keywords: dehydrogenase ; ethylene ; fruit ; gene expression ; UDP glucuronosyl/glucosyl transferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA library produced from mRNA isolated from the pericarp of wild-type tomato fruit (Lycopersicon esculentum Mill. cv Ailsa Craig) at the first visible sign of fruit ripening was differentially screened to identify clones whose homologous mRNAs were present at reduced levels in fruit of the tomato ripening mutant, ripening inhibitor,rin. Five clones were isolated (pERT 1, 10, 13, 14, 15). Accumulation of mRNA homologous to each of these clones increased during the ripening of wild-type fruit and showed reduced accumulation in ripening rin fruit. The levels of three of them (homologous to ERT 1, 13 and 14) were increased by ethylene treatment of the mutant fruit. A further clone, ERT 16 was identified for a mRNA present at a high level in both normal and mutant fruit at early stages of ripening. Database searches revealed no significant homology to the DNA sequence of ERT 14 and 15; however, DNA and derived amino acid sequence of ERT 1 both contain regions of homology with several reported UDP-glucosyl and glucuronosyl transferases (UDPGT) and with a conserved UDPGT motif. A derived amino acid sequence from the ERT 10 cDNA contains a perfect match to a consensus sequence present in a number of dehydrogenases. The ERT 13 DNA sequence has homology with an mRNA present during potato tuberisation. The presence of these mRNAs in tomato fruit is unreported and their role in ripening is unknown. The ERT 16 DNA sequence has homology with a ripening/stress-related cDNA isolated from tomato fruit pericarp.
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    URL: http://dx.doi.org/10.1007/BF00021431
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    A histidine decarboxylase-like mRNA is involved in tomato fruit ripening (1993)
    Springer
    Plant molecular biology 23 (1993), S. 627-631 
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    ISSN: 1573-5028
    Keywords: ethylene ; histamine ; gene expression ; Lycopersicon esculentum ; ripening mutant ; ripening inhibitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA sequencing of a tomato ripening-related cDNA, TOM 92, revealed an open reading frame with homology to several pyridoxal 5′-phosphate histidine decarboxylases, containing the conserved amino acid residues known to bind pyridoxal phosphate and α-fluoromethylhistidine, an inhibitor of enzyme activity. TOM 92 mRNA accumulated during early fruit ripening and then declined. Fruit of the ripeningimpaired tomato mutant, ripening inhibitor (rin), did not accumulate TOM 92 mRNA, and its accumulation was not restored by treatment of fruit with ethylene. The TOM 92 mRNA was not detected in tomato leaves and unripe fruit.
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    Cell-type specific expression of three rice genes GOS2, GOS5 and GOS9 (1993)
    Springer
    Plant molecular biology 23 (1993), S. 889-894 
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    ISSN: 1573-5028
    Keywords: gene expression ; in situ hybridization ; photosystem I subunit ; rice ; suil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cell-type-specific expression of three rice genes, GOS2, GOS5 and GOS9, was studied by mRNA in situ hybridization. Previous northern blot analysis revealed that these genes were constitutive, green tissue-specific and root-specific, respectively. In this study, GOS2 transcripts were observed in all leaf cell types. In roots, a temporal and spatial expression pattern was noticed. Higher mRNA levels were observed in lateral roots, especially in parenchymal cells of the vascular cylinder. Expression of GOS5 was mainly found in chloroplast-containing cells. For GOS9, significant levels of signal were observed in root and leaf sections.
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    Transcription of mononucleosomal particles acetylated in the presence of n-butyrate (1993)
    Springer
    Molecular biology reports 18 (1993), S. 37-41 
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    ISSN: 1573-4978
    Keywords: gene expression ; histone acetylation ; mononucleosomal particles ; RNA polymerase II ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although a correlation between chemical acetylation of the amino-terminal tails of core histones and stimulation of RNA synthesis has been reported for nucleosomal core particles (Piñeiro et al. (1991) Biochem. Biophys. Res. Commun. 177: 370), no differences in transcription are detected between acetylated and nonacetylated mononucleosomal particles obtained from HeLa cells in the presence and absence of n-butyrate. Apparently, the lysine residues modified in the presence of n-butyrate are not the same responsible for the observed acetylation-induced transcription. The acetylation obtained with n-butyrate might be significantly different from that present in transcriptionally active chromatin.
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    Hemoglobins with multiple reactive sulphydryl groups: The reaction of dog hemoglobin with 5,5′-dithiobis (2-nitrobenzoate) (1993)
    Springer
    The protein journal 12 (1993), S. 33-37 
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    ISSN: 1573-4943
    Keywords: Hemoglobin ; sulphydryl group ; ionizable groups ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Dog hemoglobin has four sulphydryl groups per (tetramer) molecule located at the G18(111)a and F9(93)β positions. The two sulphydryls at the G18(111)a positions are unreactive toward nonmercurial sulphydryl reagents, but those at the F9(93)β positions are reactive toward these reagents. We have studied the kinetics of the reaction of dog hemoglobin with 5,5′-dithiobis (2-nitrobenzoic acid) as a function ofpH. At allpH values studied, the reaction is kinetically monophasic. Quantitative analysis of thepH dependence of the apparent second-order rate constant shows that two ionizable groups are linked to the reaction of the sulphydryl group. TheirpK a values are 5.57 and 9.0. These values are assigned to HisHC3(146)β and to the CysF9(93)β sulphydryl. We find that dog carbonmonoxyhemoglobin is significantly—almost an order of magnitude—less reactive than the aquomet, azidomet, and oxy derivatives. This result may be due to a greater tendency (at acidpH) for the salt bridge between HisHC3(146)β and AspFG1(94)β to form in the carbonmonoxy than in the other derivatives. Formation of this salt bridge is known to hinder access to the CysF9(93)β sulphydryl [Perutz, M. F. (1970),Nature 228, 734–739].
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    Jasmonic acid-inducible gene expression of a Kunitz-type proteinase inhibitor in potato tuber disks (1993)
    Springer
    Plant molecular biology 21 (1993), S. 539-541 
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    ISSN: 1573-5028
    Keywords: gene expression ; jasmonic acid ; Kunitz-type proteinase inhibitor ; patatin ; potato (Solanum tuberosum L.) ; wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Messenger RNAs of a potato (Solanum tuberosum L.) Kunitz-type proteinase inhibitor(s) (PKPI) were present in potato disks excised from tubers stored for 14 months (old tubers) or 2 months (young tubers) after harvest, and disappeared during the aseptic culture. The PKPI mRNA accumulation was found to be induced in potato disks from the old tubers by the addition of jasmonic acid (JA) [3-oxo-2-(2′-cis-pentenyl)-cyclopentane-1-acetic acid].
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    Structure and expression of the S locus-related genes of maize (1993)
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    Plant molecular biology 21 (1993), S. 1171-1174 
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    ISSN: 1573-5028
    Keywords: transmembrane receptor ; protein kinase ; self-incompatibility ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The extracellular of the putative receptor-like protein kinase, ZmPK1, is related to the self-incompatibility locus (S-locus) genes of Brassica. We have isolated and characterized a genomic DNA clone of ZmPK1 and three additional genes from maize that are highly related to ZmPK1. These three S-locus related genes do not appear to have the protein kinase catalytic domain that is found in ZmPK1. One or more of these genes are expressed specifically in the silks. This initial description of S-locus related genes in monocotyledonous plants suggests that the S-locus domain may be involved in several different cellular functions in a wide variety of plants.
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    URL: http://dx.doi.org/10.1007/BF00023612
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    Calmodulin isoforms in Arabidopsis encoded by multiple divergent mRNAs (1993)
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    Plant molecular biology 22 (1993), S. 215-225 
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    ISSN: 1573-5028
    Keywords: Arabidopsis ; calmodulin sequence ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three new, unique cDNA sequences encoding isoforms of calmodulin (CaM) were isolated from an Arabidopsis cDNA library cloned in λgt10. These sequences (ACaM-4, -5, and -6) represent members of the Arabidopsis CaM gene family distinct from the three DNA sequences previously reported. ACaM-4 and -6 encode full-length copies of CaM mRNAs of ca. 0.75 kb. The ACaM-5 sequence encodes a partial length copy of CaM mRNA that is lacking sequences encoding the amino-terminal 10 amino acids of mature CaM and the initiator methionine. The derived amino acid sequence of ACaM-5 is identical to the sequences encoded by two of the previously characterized ACaM cDNAs, and is identical to TCH-1 mRNA, whose accumulation was increased by touch stimulation. The polypeptides encoded by ACaM-4 and -6 differ from that encoded by ACaM-5 by six and two amino acid substititions, respectively. Most of the deduced amino acid sequence substitutions in the Arabidopsis CaM isoforms occurred in the fourth Ca2+-binding domain. Polymerase chain reaction amplification assays of ACaM-4, -5 and -6 mRNA sequences indicated that each accumulated in Arabidopsis leaf RNA fractions, but only ACaM-4 and -5 mRNAs were detected in silique total RNA. The six different CaM cDNA sequences each hybridize with unique Eco RI restriction fragments in genomic Southern blots of Arabidopsis DNA, indicating that these sequences were derived from distinct structural genes. Our results suggest that CaM isoforms in Arabidopsis may have evolved to optimize the interaction of this Ca2+-receptor protein with specific subsets of response elements.
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    An Arabidopsis gene with homology to glutathione S-transferases is regulated by ethylene (1993)
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    Plant molecular biology 22 (1993), S. 517-523 
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    ISSN: 1573-5028
    Keywords: ethylene ; gene expression ; Arabidopsis thaliana ; glutathione S-transferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA clone obtained from Arabidopsis leaf RNA encodes a 24 kDa protein with homology to glutathione S-transferases (GST). It is most homologous with a tobacco GST (57% identity). In Arabidopsis, expression of GST mRNA is regulated by ethylene. Exposure of plants to ethylene increased the abundance of GST mRNA, while treatment with norbornadiene had the reverse effect. Ethylene had no effect on the mRNA level in ethylene-insensitive etr1 plants. The abundance of this mRNA increased with the age of plants. DNA hybridizations indicate that GSTs are encoded by a large multigene family in Arabidopsis.
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    Upstream regulatory sequences from two β-conglycinin genes (1993)
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    Plant molecular biology 22 (1993), S. 873-885 
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    ISSN: 1573-5028
    Keywords: β-conglycinin ; gene expression ; legumin box ; seed storage protein ; vicilin box
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genes encoding the β-conglycinin seed storage proteins of soybean are expressed only in seeds during specific stages of development. The different subunits of β-conglycinin, α′, α and β, are encoded by distinct members of a gene family. Yet there are marked differences in the regulation of the genes encoding the α′/α and β subunits. Previous work (Chen et al., EMBO J 7: 297–302, 1988) identified a seed specific transcriptional enhancer upstream of a gene encoding the α′ subunit. Mutations were made within this region to discern its functional components. Among those identified is a 62 bp region (between −77 and −140) that contains a vicilin box consensus sequence as well as a sequence that binds the soybean nuclear factor SEF4 in vitro. A second region, which contains a sequence homologous to the core of the legumin box consensus (i.e., CATGCAT-like or RY repeat element) at −246, was also shown to affect the activity of this enhancer in transgenic plants. A series of 5′ terminal deletions were used to identify regulatory elements upstream of the β subunit gene. Two regions were identified (from −553 to −442 and from −308 to −72) that, when deleted, led to a marked reduction in gene expression. Both of these elements contain sequences that bind SEF4 in vitro. The distal element also contains an AT-rich segment that recognizes a second nuclear factor, SEF1, in vitro. Neither of these elements contains any homology to the vicilin box consensus.
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    Molecular characterization of four chitinase cDNAs obtained fromCladosporium fulvum-infected tomato (1993)
    Springer
    Plant molecular biology 22 (1993), S. 1017-1029 
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    ISSN: 1573-5028
    Keywords: chitinase ; gene expression ; pathogenesis-related protein ; plant-fungus interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Complementary DNA clones encoding acidic and basic isoforms of tomato chitinases were isolated fromCladosporium fulvum-infected leaves. The clones were sequenced and found to encode the 30 kDa basic intracellular and the 26 and 27 kDa acidic extracellular tomato chitinases previously purified (M.H.A.J. Joostenet al., in preparation). A fourth truncated cDNA which appears to encode an extracellular chitinase with 82% amino acid similarity to the 30 kDa intracellular chitinase was also isolated. Characterization of the clones revealed that the 30 kDa basic intracellular protein is a class I chitinase and that the 26 and 27 kDa acidic extracellular proteins which have 85% peptide sequence similarity are class II chitinases. The characterized cDNA clones represent four from a family of at least six tomato chitinases. Southern blot analysis indicated that, with the exception of the 30 kDa basic intracellular chitinase, the tomato chitinases are encoded by one or two genes. Northern blot analysis showed that the mRNA encoding the 26 kDa acidic extracellular chitinase is induced more rapidly during an incompatibleC. fulvum-tomato interaction than during a compatible interaction. This difference in timing of mRNA induction was not observed for the 30 kDa basic intracellular chitinase.
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    Structure and expression of a nuclear gene for the PSI-D subunit of photosystem I inNicotiana sylvestris (1993)
    Springer
    Plant molecular biology 22 (1993), S. 985-994 
    Details
    ISSN: 1573-5028
    Keywords: ferredoxin-binding subunit ; gene expression ; gene structure ; Nicotiana sylvestris ; photosystem I ; psaD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The PSI-D subunit is the ferredoxin-binding site of photosystem I, and is encoded by the nuclear genepsaD. We isolated apsaD genomic clone fromNicotiana sylvestris, by screening a genomic library with apsaD cDNA which we previously cloned fromN. sylvestris (Yamamotoet al., Plant Mol Biol 17: 1251, 1991). Nucleotide sequence analysis revealed that this genomic clone contains apsaD gene, which does not correspond to thepsaD cDNA, so we designated these genespsaDb andpsaDa, respectively. ThepsaDb clone encodes a protein of 214 amino acids uninterrupted by introns. The N-terminal sequence determined for theN. sylvestris PSI-D protein encoded bypsaDb begins at the 49th residue. The products ofpsaDa andpsaDb share 82.7% and 79.5% identity at the amino acid and nucleotide levels, respectively. Genomic Southern analysis showed that two copies ofpsaD are present in theN. sylvestris genome. Ribonuclease protection assays and immunoblot analysis inN. sylvestris indicate that both genes are expressed in leaves, stems and flower buds, but neither is expressed in roots. During leaf development, the ratio ofpsaDb topsaDa mRNA increases from 0.12 in leaf buds to 0.36 in mature leaves. The relative abundance of the corresponding proteins decreased over the same developmental period. These results indicate that differential regulation mechanisms controlpsaDa andpsaDb expression at both the mRNA and protein levels during leaf development.
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    Fruit developmental regulation of the kiwifruit actinidin promoter is conserved in transgenic petunia plants (1993)
    Springer
    Plant molecular biology 23 (1993), S. 489-499 
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    ISSN: 1573-5028
    Keywords: kiwifruit ; actinidin ; protease activity ; GUS fusion ; gene expression ; fruit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have examined the expression of actinidin, a cysteine protease found in kiwifruit, over the course of fruit development. Protease activity was first seen in fruit that had reached about half their final weight, and rose to high levels at harvest. The 5′-flanking region (nucleotides −1301 to +58) of a kiwifruit actinidin gene was fused to the β-glucuronidase (GUS)-coding region, and the chimaeric gene was introduced into transgenic petunia plants. Induction of the GUS gene was observed during the later stages of seed pod development, closely resembling the pattern of actinidin induction in fruit tissues of kiwifruit. Some GUS expression was also detected in the vascular system of the receptacle, leaves, stems and roots. A shorter promoter fragment consisting of nucleotides −115 to +58 conferred similar spatial and temporal regulation in some of the transgenic plants.
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    Molecular characterization of maize extensin expression (1993)
    Springer
    Plant molecular biology 23 (1993), S. 685-695 
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    ISSN: 1573-5028
    Keywords: extensin ; gene expression ; hydroxyproline ; maize ; silk ; vegetative tissues
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study concerned the developmental regulation of wall-localized, hydroxyproline-containing proteins in maize tissues and organs. Silk and pericarp cell walls contained more peptidyl hydroxyproline than did walls of any vegetative tissue, although all tissues and organs accumulated these proteins as they matured. In many tissues, hydroxyproline-rich proteins are first associated with the wall in a soluble form before being insolubilized through covalent attachment to the matrix. Because hydroxyproline was more soluble earlier than later in development, it appears that insolubilization was occurring in maize tissues and organs as well. Tissue prints reacted with an anti-extensin antibody gave positive results, indicating the presence of a soluble form of this common hydroxyproline-rich glycoprotein (HRGP). Silk and pericarp cells actively synthesized this extensin from abundant transcripts. In vegetative tissues, extensin transcripts were somewhat more abundant in seedlings than in pre-anthesis or mature plants, but levels were much lower than in silk and pericarp. Southern blots of maize genomic DNA indicated that these extensin transcripts are encoded by a small multigene family. Potential roles for extensin in reproductive/protective tissues versus the embryo or vegetative tissues are suggested.
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    Metabolic regulation of α-amylase gene expression in transgenic cell cultures of rice (Oryza sativa L.) (1993)
    Springer
    Plant molecular biology 23 (1993), S. 737-747 
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    ISSN: 1573-5028
    Keywords: α-amylase ; transgenic cell culture ; gene expression ; metabolic regulation ; Oryza sativa ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Expression of two genes in the α-amylase gene family is controlled by metabolic regulation in rice cultured cells. The levels of RAmy3D and RAmy3E mRNAs in rice cultured cells are inversely related to the concentration of sugar in the culture medium. Other genes in the rice α-amylase gene family have little or no expression in cultured cells; these expression levels are not controlled by metabolic regulation. A RAmy3D promoter/GUS gene fusion was metabolically regulated in the transgenic rice cell line 3DG, just as the endogenous RAmy3D gene is regulated. An assay of GUS enzyme activity in 3DG cells demonstrated that RAmy3D/GUS expression is repressed when sugar is present in the culture medium and induced when sugar is removed from the medium. The 942 bp fragment of the RAmy3D promoter that was linked to the coding region of the GUS reporter gene thus contains all of the regulatory sequences necessary for metabolic regulation of the gene.
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    Initial steps of αand β-d-glucose binding to intact red cell membrane (1993)
    Springer
    The journal of membrane biology 132 (1993), S. 167-178 
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    ISSN: 1432-1424
    Keywords: red cell ; glucose transport protein ; GLUT1 ; kinetics ; rapid reactions ; tryptophan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The kinetics of the initial phases of d-glucose binding to the glucose transport protein (GLUT1) of the human red cell can be followed by stopped-flow measurements of the time course of tryptophan (trp) fluorescence enhancement. A number of control experiments have shown that the trp fluorescence kinetics are the result of conformational changes in GLUT1. One shows that nontransportable l-glucose has no kinetic response, in contrast to d-glucose kinetics. Other controls show that d-glucose binding is inhibited by cytochalasin B and by extracellular d-maltose. A typical time course for a transportable sugar, such as d-glucose, consists of a zero-time displacement, too fast for us to measure, followed by three rapid reactions whose exponential time courses have rate constants of0.5–100 sec+−1 at 20°C. It is suggested that the zero-time displacement represents the initial bimolecular ligand/GLUT1 association. Exponential 1 appears to be located at, or near, the external membrane face where it is involved in discriminating among the sugars. Exponential 3 is apparently controlled by events at the cytosolic face. Trp kinetics distinguish the K d of the epimer, d-galactose, from the K dfor d-glucose, with results in agreement with determinations by other methods. Trp kinetics distinguish between the binding of the α- and β-d-glucose anomers. The exponential 1 activation energy of the β-anomer, 13.6 ± 1.4 kcal mol+−1, is less than that of α-d-glucose, 18.4 ± 0.8 kcal mol+−1, and the two Arrhenius lines cross at ≈23.5°C. The temperature dependence of the kinetic response following α-d-glucose binding illustrates the interplay among the exponentials and the increasing dominance of exponential 2 as the temperature increases from 22.3 to 36.6°C. The existence of these interrelations means that previously acceptable approximations in simplified reaction schemes for sugar transport will now have to be justified on a point-to-point basis.
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    Characterization of ion channels from Acetabularia plasma membrane in planar lipid bilayers (1993)
    Springer
    The journal of membrane biology 133 (1993), S. 145-160 
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    ISSN: 1432-1424
    Keywords: Acetabularia ; K+ channels ; kinetics ; planar lipid bilayers ; voltage dependence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Plasma membrane from Acetabularia acetabulum was prepared by aqueous-polymer two-phase partitioning and incorporated into planar 1-palmitoyl-2-oleoyl phosphatidylethanolamine bilayers by stirring in the presence of a (cis∶trans) 325∶100 mm KCl gradient. Under these conditions five distinct K+-selective channels were observed which had unitary chord-conductances (determined between 30 mV either side of the reversal potential) and frequencies of incorporation (in parentheses) of 1,600 pS (26%), 485 pS (21%), 259 pS (53%), 140 pS (37%) and 27 pS (37%). Two Cl−-selective channels were also observed, which had unitary chord-conductances of 8 and 48 pS and were present in 21 and 16% of bilayers, respectively. The voltage dependencies of channel open probability (P o ), open-state time constant (τ o) and closed-state time constant (τ c) were determined for the 259, 140 and 27 pS K+ channels. The P o of all three channels increased with increasingly positive membrane potentials. Thus, since these channels were oriented with their extracellular face adjacent to the cis chamber, which was grounded, all would exhibit outward rectification in vivo. Changes in P o were effected by modulation of τ c in all channels, which shortened as membrane potentials became more positive, and also of τ o in the 140 and 27pS channels, which increased as membrane potentials became more positive. Extracellular (cis) KCl concentration (and/or the KCl gradient across the bilayer) affected the P o of all three K+ channels, shifting the P o /membrane potential relationship in the direction of the change in the potassium reversal potential. In all channels this was achieved largely by changes in τ c .
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    Study of the mechanism of the addition of benzyl bromide to trimethylvinylsilane in the presence of the Fe(CO)5—DMF system (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 1352-1356 
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    ISSN: 1573-9171
    Keywords: benzyl bromide, trimethylvinylsilane, addition ; radicals ; metal-complex initiation ; kinetics ; mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The general kinetics of the addition of benzyl bromide to trimethylvinylsilane in the presence of the Fe(CO)5—DMF system has been studied. The reaction orders with respect to each reagent found in the study correspond to a radical chain mechanism of the process. The metal-complex system takes part only in the initiation stage and only at a strictly defined ratio of the components.
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    The influence of the mercury and thallium atoms in organomercury and organothallium nitroxyl radicals on their reactivity (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 205-207 
    Details
    ISSN: 1573-9171
    Keywords: kinetics ; organomercury nitroxyls ; organothallium nitroxyls ; coordination bond ; hydrazobenzene ; reduction ; rate constant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An increase is found in the reactivity of organomercury and organothallium nitroxyl mono- and biradicals of the imidazoline type in comparison with the analogous compounds without organometallic fragments. This is explained by the formation of coordination bonds N→Hg, N→Tl, and N→O→Hg.
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    Cationic polymerization of hydrocarbon monomers under the action of acyl halide complexes with Lewis acids (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 837-840 
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    ISSN: 1573-9171
    Keywords: cationic polymerization ; polyisobutylene ; Lewis acids ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Polymerization of isobutylene in hexane at −78 °C under the action of the complex AcBr · 2AlBr3 (Ac-2) affords polyisobutylene having C=O groups at the head and C-Br or C=C groups at the tail of all the molecules. The presence of the latter indicates that there occurs proton elimination from the growing carbocation with the formation of a superacid HBr · 2AlBr3 which is unable to initiate the polymerization repeatedly under given contitions. This makes it possible to consider proton elimination as the reaction of the decay of active centers with the rate constantk d. This value has been calculated from the rate of accumulation of the polymeric molecules having terminal C=C bonds:k d=3.5 · 10−4 s−1. The rate constant of chain growthk g has been determined from polymerization kinetics and from the content of active centers:k g=6.2 L mol−1 s−1.
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    Reactions of hydrazobenzene and tetranitromethane with nitroxyl radicals (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 1027-1031 
    Details
    ISSN: 1573-9171
    Keywords: nitroxyls ; hydrazobenzene ; reduction ; tetranitromethane ; oxidation ; kinetics ; constants ; mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The values of isotropic HFS constantsa N were obtained for nitroxyl radicals (NR) of the piperidine series in hexane and water. The interrelation between rate constants for NR reduction and oxidation reactions, isotropic HFS constantsa N, inductive constants σ″ of the piperidine substituents, and electrochemical characteristics of NR were found. The dependence of the rate constants for the reduction of NR by hydrazobenzene (HB) and its oxidation by tetranitromethane (TNM) upon the Hammett type inductive constantsσ EPR, obtained using HFS constantsa N as the basis, was analyzed. The solvent effect on the reduction and oxidation reaction rate constants, the kinetic isotopic effect of the reduction reaction for a number of NR-HB systems, and alternative reaction mechanisms are considered.
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    Kinetics and mechanism of thermal decomposition of hydroxylammonium nitrate (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 1811-1815 
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    ISSN: 1573-9171
    Keywords: hydroxylammonium nitrate ; preparation ; thermal decomposition ; kinetics ; mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of thermal decomposition of melted hydroxylammonium nitrate have been investigated by the rate of heat production in the temperature range 84.8–120.9°C. The decomposition proceeds with autocatalysis and up to 60 % of conversion the rate of the process increases proportionally to the square of the degree of decomposition. The initial rate is proportional to the square of the concentration of HNO3 formed due to dissociation of the salt. The activation energy of this process is 15.3±1.8 kcal/mol. It is suggested that the initial stage the process proceeds via interaction between N2O3 and NH3OH+, whereas the subsequent acceleration is due to oxidation of NH3OH+ by nitrogen oxides formed as well as by nitrous acid.
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    Some laws governing the alkylation of 6-tert-butyl-2-methylphenol with methyl acrylate in the presence of a phenoxide (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 457-460 
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    ISSN: 1573-9171
    Keywords: kinetics ; mechanism ; 6-tert-butyl-2-methylphenol ; alkylation with methyl acrylate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A kinetic scheme of the reaction between 6-tert-butyl-2-methylphenol and methyl acrylate in the presence of an alkali metal phenoxide has been proposed. The rate constants of the elementary steps describing the catalytic mechanism have been calculated. The reaction gives methyl 3-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionate as the only product (Calkylation). The nature of the metal cation does not affect the reaction mechanism.
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    Investigation of the process of polyimide formation from complexes of the diester of benzophenonetetracarboxylic acid with diamines (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 255-258 
    Details
    ISSN: 1573-9171
    Keywords: H-complexes ; polyimide ; 3,3′,4,4′-benzophenonetetracarboxylic acid, diethyl ester ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of thermal imidization of the H-complexes derived from the diethyl ester of 3,3′,4,4′-benzophenonetetracarboxylic acid (EBZP) and various diamines have been studied. A comparison of kinetic parameters obtained for the imidization of H-complexes based on ethyl or methyl esters of this acid has disclosed the differences in the behavior of each of the two H-bonds and the contribution of each bond to the mechanism of polyimide formation from the respective H-complexes.
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    Expression of thelacZ gene targeted to the HPRT locus in embryonic stem cells and their derivatives (1993)
    Springer
    Transgenic research 2 (1993), S. 1-13 
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    ISSN: 1573-9368
    Keywords: gene expression ; lacZ ; HPRT ; ES cells ; gene targeting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transgenes in mice often exhibit different expression patterns in different transgenic lines. While the basis for this phenomenon is not understood, it is widely believed that the site at which the transgene becomes integrated into the mouse genome is a major factor in determining the pattern of expression. Most transgenic mice have been produced by microinjection of DNA into the male pronucleus, which results in integration of tandem arrays of the transgene at random chromosomal sites. In the experiments described in this report, electroporation of embryonic stem (ES) cells was used to place single copies of alacZ transgene into either random sites or into the HPRT (hypoxanthine phosphoribosyl transferase) locus of the mouse genome. Expression oflacZ was assayed by histochemical staining forEscherichia coli β-galactosidase activity in ES cells and in differentiated derivatives obtained by teratocarcinoma formation. Several of the randomly integrated cell lines expressedlacZ at high levels in a variety of cell types present in the tumours, but most notably in epithelial cells. Targeted cell lines withlacZ in opposite orientation to the direction of HPRT gene transcription also expressed well in epithelial cells, but the targeted cell lines did not express in a wider variety of cell types than some of the nontargeted cell lines. Targeted cell lines transcribinglacZ in the same orientation as HPRT transcription did not express high levels oflacZ in any differentiated cell type. Analysis of transcripts suggested that this orientation effect may have been the result of transcriptional interference perpetrated by the HPRT gene promoter.
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    Mechanism and Kinetics of Metal Ion-Mediated Degradation of Fosinopril Sodium (1993)
    Springer
    Pharmaceutical research 10 (1993), S. 800-809 
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    ISSN: 1573-904X
    Keywords: fosinopril sodium ; magnesium ions ; C–P bond cleavage ; kinetics ; mechanism ; tablet formulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Fosinopril sodium (I), a new angiotensin converting enzyme inhibitor, is a diester prodrug of the active moiety II. We report here a novel transformation of fosinopril into β-ketoamide, III, and a phosphonic acid, IV, mediated through metal ion participation. The interaction of fosinopril with magnesium ions was studied in a solution model system in which methanol was used as the solvent and magnesium acetate as the source of metal ions. Kinetic analysis indicated the degradation to be a bimolecular process, with the rate being first order in both metal ion and fosinopril concentration. The degradation products II, III, and IV effectively retarded the magnesium ion mediated reaction of fosinopril. Based on the results of 31P-NMR, 1H-NMR, Mn(II)-EPR spectroscopy experiments and mass spectrometry, a mechanism is postulated for this transformation. A key reactive intermediate has been characterized that supports the proposed mechanism. The results can account for the observed degradation profile of the fosinopril sodium in a prototype tablet formulation.
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    URL: http://dx.doi.org/10.1023/A:1018940623174
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    Different expression of calpain in skeletal muscle of Japanese quail (Coturnix coturnix japonica) lines selected for body weight (1993)
    Springer
    Biochemical genetics 31 (1993), S. 485-495 
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    ISSN: 1573-4927
    Keywords: muscle protein degradation ; calpain ; gene expression ; genetic variation ; Japanese quail
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Calpain activity was determined by western blot analysis of steady-state concentrations ofm-calpain (calpain requiring millimolar Ca2 for activation) and also by northern blot analysis of steady-state concentrations of mRNA encodingm-calpain in three lines of quail: a random-bred control line (RR) and two lines selected for body weight, one for increased body weight (LL) and another for decreased body weight (SS). Them-calpain activities in skeletal muscle were higher in the SS line and lower in the LL line. From western blot analysis, enzyme levels of calpain were almost the same for all three lines. At the level of gene expression, the mRNA concentration encodingm-calpain was higher in the LL and lower in the SS line. These results suggest that the regulation of calpain activity in skeletal muscle is a three-step process, regulation at the transcription level, regulation at the enzyme level, and regulation of the activation of calpain.
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    Kinetic analysis of AUC-dependent saturable clearance of liposomes: Mathematical description of AUC dependency (1993)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 21 (1993), S. 299-308 
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    ISSN: 1573-8744
    Keywords: saturation ; liposomes ; uptake ; Michaelis-Menten ; kinetics ; AUC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The objective of this study was to examine the AUCdependency of saturable hepatic clearance (CL h )of liposomes and to postulate a mathematical model to describe the characteristics. The AUCdependency of saturable CL h was examined under intravenous rapid administration at various doses. The CL h increased with increasing blood concentration but decreased with the increase of AUCat each dose. In addition, the relationship between AUCand CL h was consistent with that observed in previously reported infusion studies. These experimental data confirm the AUCdependency of saturable CL h of liposomes. A mathematical model was developed for this AUCdependency. The decrease of CL h was described by the uptake amount (X)as follows: CL h =CL m (1−X/X m ),where CL m and X m represent the maximum uptake clearance and the maximum uptake amount, respectively. The rate equation for uptake was analytically solved as CL h =X/AUC=X m AUC(1-exp(CL m /X m AUC)).Uptake clearance can be described by CL m , X m ,and AUC,and so uptake clearance is constant if AUCis constant. These experimental analyses and theoretical considerations show the validity of the AUC-dependent saturable CL h of liposomes.
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    Molecular biological approaches to plant nutrition (1993)
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    Plant and soil 155-156 (1993), S. 21-31 
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    ISSN: 1573-5036
    Keywords: nitrogen ; sulphur-nutrition ; gene cloning ; gene expression ; regulation ; crop improvement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In the last decade, understanding of ion transport has grown sufficiently to pose sensible questions about the molecular nature of the processes and their regulation. Techniques for identifying and cloning genes and for genetic transformation provide the means for answering these questions. Transport of ions across membranes is obviously a major aspect of mineral nutrition since it occurs during initial absorption, compartmentation and mobilisation of nutrients. Here, we will briefly review the types of transport protein involved and show how molecular biology and recombinant DNA technology have revealed something of their structure. Strategies used to identify the genes for transporters are discussed and reference is made to areas in which the availability of cloned genes will facilitate future studies. Mineral nutrition involves, however, more than membrane transport. The absorption rates of major nutrients are quite strictly regulated by biochemical factors which vary with the rate at which nutrients are used in growth. Nitrogen, sulphur and phosphate nutrition in micro-organisms are regulated by the interaction of various DNA-binding proteins with the promoter regions of genes for key enzymes in the assimilatory pathways and the specific ion permeases. The expression of the regulatory protein or its activity can be modified by metabolites, such as glutamine. Some evidence supports the idea that higher plants also have groups of genes with a common regulation of expression. An attempt is made to identify some reasonable objectives, which should increase understanding of the regulation of nutrient transport.
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    Developmental expression of glutathione-S-transferase in maize and its possible connection with herbicide tolerance (1993)
    Springer
    Euphytica 67 (1993), S. 221-230 
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    ISSN: 1573-5060
    Keywords: Zea mays ; glutathione-S-transferase ; glutathione ; herbicide tolerance ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Crop improvement for tolerance to specific herbicides is an important breeding target, since molecules performing well with regard to environmental safety are frequently not completely selective for crops. The glutathione (GSH)/glutathione-S-transferase (GST) system is a general mechanism of detoxification that in higher plants may confer tolerance to some herbicides. GSH level and GST activity were measured in different maize inbred lines, in the absence or in the presence of EPTC (a thiocarbamate) and of Alachlor (a chloroacetanilide); a wide genetic variability was observed for these parameters, which appear to be involved in plant tolerance to herbicides. Isozyme analysis was performed on roots, leaves, scutellum, pollen, coleoptile, mesocotyl of the same inbreds: it revealed the presence of many GST forms in maize, showing high polymorphism; they are controlled by at least five genes, the expression of which is developmentally regulated in the different tissues analyzed.
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    Solanum phureja genes are expressed in the leaves and tubers of aneusomatic potato dihaploids (1993)
    Springer
    Euphytica 69 (1993), S. 1-6 
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    ISSN: 1573-5060
    Keywords: gene expression ; isozymes ; patatin ; potato dihaploids ; Solanum phureja
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The expression of leaf isozymes and tuber patatin in dihaploids derived from the Solanum tuberosum cv. Pentland Crown was investigated. Seven of the dihaploids were aneusomatic containing additional chromosomes from the S. phureja dihaploid inducer. Of these, four genotypes expressed leaf isozymes characteristic of the S. phureja dihaploid inducer, and the tubers of three aneusomatic dihaploids contained a S. phureja form of patatin. Aneusomatic dihaploids in which the proportion of cells containing additional S. phureja chromosomes was relatively small (i.e. 1–15%) did not express leaf isozyme markers or patatin bands characteristic of the dihaploid inducer or showed only faint expression of one or two markers. However, those with a high proportion of cells containing additional chromosomes (50–55%) had a range of strongly expressed leaf isozymes that were characteristic of the dihaploid inducer and also expressed the S. phureja tuber patatin. One dihaploid genotype was exclusively euploid (2n〈24), yet is expressed a S. phureja leaf isozyme marker and S. phureja tuber patatin, suggesting recombination or chromosome substitution between the genome of the S. phureja dihaploid inducer and the cultivar Pentland Crown.
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    Redox control of gene expression and the function of chloroplast genomes — an hypothesis (1993)
    Springer
    Photosynthesis research 36 (1993), S. 95-102 
    Details
    ISSN: 1573-5079
    Keywords: chloroplast genome ; electron transport ; evolution ; gene expression ; redox response regulators ; redox sensors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two-component regulatory systems that respond to changes in redox potential have recently been discovered in bacteria. ‘Redox sensors’ are defined as electron carriers which initiate control of gene expression upon oxidation or reduction. ‘Redox response regulators’ are defined as DNA-binding proteins which modify gene expression as a result of the action of redox sensors. Redox sensors and redox response regulators may comprise a mechanism for feedback control of redox potential in photosynthetic electron transport chains, thereby protecting plants, algae and photosynthetic bacteria from damage caused by electrochemistry operating on inappropriate electron donors and acceptors. Chloroplast redox sensors and redox response regulators, themselves encoded in the nucleus, may place chloroplast gene expression under redox regulatory control. This may account for the persistence, in evolution, of chloroplast genomes, and for the constancy of the sub-set of chloroplast proteins encoded and synthesised in situ. These and other predictions are discussed.
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    Flash-induced proton transfer in photosynthetic bacteria (1993)
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    Photosynthesis research 37 (1993), S. 1-17 
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    ISSN: 1573-5079
    Keywords: bacterial photosynthesis ; kinetics ; proton binding ; reaction center ; stoichiometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A proton electrochemical potential across the membranes of photosynthetic purple bacteria is established by a light-driven proton pump mechanism: the absorbed light in the reaction center initiates electron transfer which is coupled to the vectorial displacement of protons from the cytoplasm to the periplasm. The stoichiometry and kinetics of proton binding and release can be tracked directly by electric (glass electrodes), spectrophotometric (pH indicator dyes) and conductimetric techniques. The primary step in the formation of the transmembrane chemiosmotic potential is the uptake of two protons by the doubly reduced secondary quinone in the reaction center and the subsequent exchange of hydroquinol for quinone from the membrane quinone-pool. However, the proton binding associated with singly reduced promary and/or secondary quinones of the reaction center is substoichiometric, pH-dependent and its rate is electrostatically enhanced but not diffusion limited. Molecular details of protonation are discussed based on the crystallographic structure of the reaction center of purple bacteriaRb. sphaeroides andRps. viridis, structure-based molecular (electrostatic) calculations and mutagenesis directed at protonatable amino acids supposed to be involved in proton conduction pathways.
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    Differences in uptake kinetics of ammonium and nitrate in legumes and cereals (1993)
    Springer
    Plant and soil 154 (1993), S. 67-72 
    Details
    ISSN: 1573-5036
    Keywords: ammonium uptake ; cereals ; kinetics ; legumes ; 15N ; nitrate uptake ; translocation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Influx isotherms were obtained for nitrate and ammonium from three legumes, Cajanus cajan (L.) Millsp., Cicer arietinum L. and Arachis hypogaea L. and three cereals, Sorghum bicolor (L.) Moench., Pennisetum glaucum L. and Zea mays L. The transition in influx isotherms for both nitrogen sources was found to be within the concentration range (0.05–2.5 mM) tested. There were significant differences in Km and Vmax for ammonium between legumes and cereals. The difference in the kinetic properties for nitrate uptake between the two groups of plants only became apparent at the higher concentration tested. Legumes translocated absorbed nitrate and ammonium to shoots more rapidly than cereals. Results show that there are significant differences in uptake and translocation of ammonium and nitrate between legumes and cereals.
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    Molecular approaches to the study of evolution and phylogeny of the Nemertina (1993)
    Springer
    Hydrobiologia 266 (1993), S. 255-265 
    Details
    ISSN: 1573-5117
    Keywords: gene expression ; nucleotide sequence ; invertebrate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Molecular biological tools currently available to us are revolutionizing the way in which we can address questions in evolutionary biology. The purpose of this article is to provide an overview of molecular techniques and applications available to biologists who are interested in evolutionary studies but who have little acquaintance with molecular biology. In evolutionary biology, techniques designed to determine degree of nucleic acid similarity are in common use and will be dealt with first. Another approach, namely gene expression studies, has strong implications for evolutionary biology but generally requires substantial familiarity with molecular biological tools. Expression studies provide powerful tools for discerning processes of speciation, as in the selection of genetic variants, as well as discerning lineages, e.g., expression of specific homeobox genes during segment formation. For investigations where either nucleic acid identity or gene expression are the ultimate goal, detailed information, protocols and appropriate controls are beyond the scope of this work but, where possible, recent review articles are cited.
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    Kinetics and specificity of alginate lyases (1993)
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    Hydrobiologia 260-261 (1993), S. 557-561 
    Details
    ISSN: 1573-5117
    Keywords: alginate lyase ; specificity ; kinetics ; product inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A purified preparation of the extracellular alginate lyase has been used to study kinetics and specificity towards purified, homopolymeric fragments of alginate. The enzyme preparation from Bacillus circulans 1351 degraded both block types, although with different efficiency, and thus appears to be nonspecific. Addition of calcium ions markedly enhanced the reaction rate for the polymannuronate block but had little or no effect on the reaction with polyguluronate. Michaelis-Menten kinetics are not obeyed in the absence of calcium ions and only for the polymannuronate in the presence of calcium The study of progress curves in response to variation in substrate and enzyme concentrations strongly suggests that the abalone lyase is subject to a reversible product inhibition.
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    URL: http://dx.doi.org/10.1007/BF00049070
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    Kinetic studies of embryo development and nutrient utilization in an alfalfa direct somatic embryogenic system (1993)
    Springer
    Plant cell, tissue and organ culture 33 (1993), S. 67-73 
    Details
    ISSN: 1573-5044
    Keywords: alfalfa (Medicago falcata) ; direct somatic embryogenesis ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method for direct somatic embryogenesis in alfalfa (Medicago falcata) is described. The time course in the development phase has been followed for fresh weight, cell density, pH, sugar uptake and embryo number and type. The method of disrupting the explant material has also been shown to influence subsequent embryo formation.
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    URL: http://dx.doi.org/10.1007/BF01997600
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    Functional properties of purified and reconstituted mitochondrial metabolite carriers (1993)
    Springer
    Journal of bioenergetics and biomembranes 25 (1993), S. 525-535 
    Details
    ISSN: 1573-6881
    Keywords: Mitochondria ; transport ; carrier proteins ; reconstitution ; kinetics ; liposomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Eight mitochondrial carrier proteins were solubilized and purified in the authors' laboratories using variations of a general procedure based on hydroxyapatite and Celite chromatography. The molecular mass of all the carriers ranges between 28 and 34 kDa on SDS-PAGE. The purified carrier proteins were reconstituted into liposomes mainly by using a method of detergent removal by hydrophobic chromatography on polystyrene beads. The various carriers were identified in the reconstituted state by their kinetic properties. A complete set of basic kinetic data including substrate specificity, affinity, interaction with inhibitors, and activation energy was obtained. These data closely resemble those of intact mitochondria, as far as they are available from the intact organelle. Mainly on the basis of kinetic data, the asymmetric orientation of most of the reconstituted carrier proteins were established. Several of their functional properties are significantly affected by the type of phospholipids used for reconstitution. All carriers which have been investigated in proteoliposomes function according to a simultaneous (sequential) mechanism of transport; i.e., a ternary complex, made up of two substrates and the carrier protein, is involved in the catalytic cycle. The only exception was the carnitine carrier, where a ping-pong mechanism of transport was found. By reaction of particular cysteine residues with mercurial reagents, several carriers could be reversibly converted to a functional state different from the various physiological transport modes. This “unphysiological” transport mode is characterized by a combination of channel-type and carrier-type properties.
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    URL: http://dx.doi.org/10.1007/BF01108409
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    Characteristics of the energy-transducing NADH-quinone oxidoreductase ofParacoccus denitrificans as revealed by biochemical, biophysical, and molecular biological approaches (1993)
    Springer
    Journal of bioenergetics and biomembranes 25 (1993), S. 339-345 
    Details
    ISSN: 1573-6881
    Keywords: NADH-quinone oxidoreductase ; Paracoccus denitrificans ; gene cluster ; H+ pump ; gene expression ; FMN ; iron-sulfur cluster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract A comparison of the mitochondrial NADH-ubiquinone oxidoreductase and the energy-transducing NADH-quinone oxidoreductase (NDH-1) ofParacoccus denitrificans revealed that both systems have similar electron-transfer and energy-transduction pathways. In addition, both complexes are sensitive to the same inhibitors and contain similar electron carriers, suggesting that theParacoccus NDH-1 may serve as a useful model system for the study of the human enzyme complex. The gene cluster encoding theParacoccus NDH-1 has been cloned and sequenced. It is composed of 18,106 base pairs and contains 14 structural genes and six unidentified reading frames (URFs). The structural genes, URFs, and their polypeptides have been characterized. We also discuss nucleotide sequences which are believed to play a role in the regulation of the NDH-1 gene cluster andParacoccus NDH-1 subunits which may contain the binding sites of substrates and/or electron carriers.
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    URL: http://dx.doi.org/10.1007/BF00762459
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    Methodology of using vaccinia virus to express foreign genes in tissue culture (1993)
    Springer
    Methods in cell science 15 (1993), S. 72-81 
    Details
    ISSN: 1573-0603
    Keywords: vaccinia virus ; orthopox virus ; recombination ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A basic technique is described for inserting any foreign gene into poxvirus by in vitro recombination. Also described is a method for identifying and plaque-purifying recombinant poxvirus containing the foreign gene using nitrocellulose filters and DNA hybridization. Immunologic techniques are presented for analyzing expression of the foreign gene, either on the surface membrane or inside infected cells.
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    URL: http://dx.doi.org/10.1007/BF01667365
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    Nutrient-limited microbial growth kinetics: overview and recent advances (1993)
    Springer
    Antonie van Leeuwenhoek 63 (1993), S. 225-235 
    Details
    ISSN: 1572-9699
    Keywords: kinetics ; transport ; collision frequency ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Traditional concepts of nutrient uptake and growth kinetics as linked by cell yield are presented. Phenomena affecting the kinetics are examined along with a discussion of those which lead to ambiguity. Concepts of flux control are presented to help understand the distribution of material along metabolic pathways. Specific affinity is described to relate nutrient accumulation rates to transporter density. It is shown to be a primary kinetic constant and the best available index of nutrient collection ability. As an aid to understanding, specific affinity is reexpressed in terms of membrane permeability. Formulations of nutrient transport rate as a function of cellular composition, particularly transporter and enzyme content and known as janusian kinetics, are described as an improvement to specific affinity theory. Procedures for quantified unidirectional fluxes are reviewed to identify the difference between gross and net transport rates of substrate. Collision frequency theory is used to show that in addition to total biomass, cell size and transporter density should also be included in rate equations describing microbial growth. Theory diversity suggests that one reason for microbial metabolic is that the likelihood of additional collisions of substrate molecules with a cell surface, after an initial collision, requires only a sparse distribution of transporter sites for maximal rate, leaving room for additional transporters able to collect other substrate types.
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    URL: http://dx.doi.org/10.1007/BF00871220
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    Dynamics of microbial growth and metabolic activity and their control by aeration (1993)
    Springer
    Antonie van Leeuwenhoek 63 (1993), S. 353-373 
    Details
    ISSN: 1572-9699
    Keywords: aeration ; bioreactor ; growth ; inhibition ; kinetics ; metabolism ; microorganism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The optimization of fermentation processes depends to a large extent on the modelling of microbial activity under complex environmental conditions where aeration is an important limiting and control factor. Simple relationships are used to establish the sensitivity of cultures to oxygen stress. Specific limitation coefficients which can be determined in laboratory reactors allow a projection to industrial operation and the definition of appropriate aeration and agitation profiles. Optimum control can be assured on the basis of directly measurable process parameters. This is shown for the case of ethanol production usingS. cerevisiae at high cell dry weight concentrations.
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    URL: http://dx.doi.org/10.1007/BF00871230
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    Biodegradation kinetics of a mixture containing a primary substrate (phenol) and an inhibitory co-metabolite (4-chlorophenol) (1993)
    Springer
    Biodegradation 4 (1993), S. 3-21 
    Details
    ISSN: 1572-9729
    Keywords: cometabolism ; cosubstrate ; 4-chlorophenol ; inhibition ; kinetics ; modeling ; monooxygenase ; phenol ; substrate interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Batch experiments on the simultaneous utilization of phenol (primary substrate) and 4-chlorophenol (cometabolic secondary substrate) demonstrated two critical substrate interactions. First, the cometabolic degradation of 4-chlorophenol was proportional to the rate of phenol oxidation, which provided the electrons for the initial monooxygenase reaction. Second, 4-chlorophenol inhibited the oxidation of the primary substrate, phenol. Modeling analyses of the degradation of phenol alone and of phenol and 4-chlorophenol together showed that the proportionality between phenol and 4-chlorophenol degradation rates averaged 0.1 mg 4-CP/mg phenol, which corresponds to 0.5% of the electrons generated by phenol oxidation being used as a cosubstrate for the monooxygenase reaction of 4-chlorophenol. In addition, modeling analyses suggest that 4-chlorophenol was a noncompetitive inhibitor of phenol oxidation for high phenol concentrations, but a competitive inhibitor for low phenol concentrations.
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    URL: http://dx.doi.org/10.1007/BF00701451
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    Slow oxygen release on the first two flashes in chemically stressed Photosystem II membrane fragments results from hydrogen peroxide oxidation (1993)
    Springer
    Photosynthesis research 38 (1993), S. 425-431 
    Details
    ISSN: 1573-5079
    Keywords: hydrogen peroxide ; hydroxylamine ; kinetics ; manganese ; oxygen release ; photosynthesis ; Photosystem II
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Flash-induced amperometric signals were measured with a Joliot-type O2 rate electrode in spinach Photosystem II (PS II) membrane fragments exposed to very low concentrations of added hydroxylamine or hydrogen peroxide. In both cases ‘anomalous O2 signals’ were observed on the first two flashes, and oscillating four-flash patterns were observed on subsequent flashes. The anomalous signals were eliminated in the presence of catalase but not EDTA. The rise times of the O2-release kinetics associated with the anomalous signals were slow (ca. 20 ms with NH2OH and ca. 120 ms with H2O2) compared to the kinetics of O2 release on subsequent flashes and in control membranes (3–6 ms). It is proposed that when the intact PS II O2-evolving complex is perturbed with small concentrations of added reductant, H2O2 can gain access and bind to the complex. Bound H2O2 can then reduce lower S states in some centers leading to anomalous O2 signals on the first two flashes. A model is presented to explain both types of anomalous O2 production. Oxygen observed on the third and subsequent flashes is due to the normal photosynthetic O2-evolution process arising from the S3-state. Anomalous O2 production could be a protective mechanism in PS II centers subjected to stress conditions.
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    URL: http://dx.doi.org/10.1007/BF00046770
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    Regulation of olfactory neuron gene expression (1993)
    Springer
    Cytotechnology 11 (1993), S. 17-22 
    Details
    ISSN: 1573-0778
    Keywords: olfactory neuroepithelium ; neural development and regeneration ; neuronal phenotype ; gene expression ; OMP ; transgenic mice ; B50/GAP43 ; OLF-1 ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00749053
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    The kinetics and regulation of M-xylose transport in Candida utilis (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 357-360 
    Details
    ISSN: 1573-0972
    Keywords: Candida utilis ; inhibition ; kinetics ; regulation ; sugar ; transport ; xylose ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Low-affinity (K m=67.6±3.2 mM) and high-affinity (K m=1.9±1.2 mM) D-xylose transport occur in Candida utilis grown, respectively, on D-glucose or D-xylose. Starvation of glucose-grown cells decreases the K m value (10.5±2.6 mm). The high-affinity system appearing during starvation required protein synthesis and it was inactivated when cells were exposed to glucose, by a process independent of protein synthesis. High-affinity transport was accompanied by transient alkalinization of yeast suspensions, indicating that it is a proton symport, whereas low-affinity transport was not. Both systems, however, were inhibited by metabolic inhibitors and by replacing H2O in the transport assay with D2O, indicating that both may be proton symports. Glucose and acetic acid also inhibited both high-and low-affinity xylose transport.
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    URL: http://dx.doi.org/10.1007/BF00383080
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    Gene expression in Pseudomonas (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 433-443 
    Details
    ISSN: 1573-0972
    Keywords: Alginate ; gene expression ; negative regulators ; positive regulators ; promoters ; Pseudomonas ; TOL plasmid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Gene regulation studies in pseudomonad bacteria are mainly restricted to Pseudomonas aeruginosa and Pseudomonas putida. Constitutive promoters exhibit DNA sequences similar to the σ 70-dependent constitutive promoters of Escherichia coli. The TOL meta-cleavage pathway operon promoter and the nah operon promoters are the best characterized σ 70-dependent promoters, which exhibit-10 regions rich in As and Ts and non-conserved-35 regions. The DNA binding motif recognized by the respective positive regulators lies between-40 and-80. Another set of positively controlled promoters exhibit upstream activator sequences located between-100 and-500. Transcription stimulation from some of these promoters also involves σ 54 and/or IHF protein. In this class of promoters, DNA binding is required to establish open complexes. Promoters for the utilization of histidine (hut) are under negative control by the HutC protein. hut promoters exhibit-10/-35 consensus regions and an overlapping operator sequence between-15 and-50. Repression of hut promoters seems to be achieved through steric hindrance of RNA polymerase. Another set of promoters are controlled by catabolite repression, which seems to be cyclic-AMP independent.
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    URL: http://dx.doi.org/10.1007/BF00328031
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    Expression of fungal genes involved in penicllin biosynthesis (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 461-467 
    Details
    ISSN: 1573-0972
    Keywords: Aspergillus nidulands ; catabolite repression ; gene expression ; penicillin ; Penicillium chrysogenum ; Plectomycetes ; regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Carbon catabolite repression and pH regulation are regulatory circuits with a wide domain of action in the Plectomycetes. Penicillin biosynthesis is one of the pathways which are under their control. The conclusions obtained so far, which are based on studies of the genetic and molecular regulation of the penicillin pathway of Aspergillus nidulans, would have been much harder to produce using an organism such as Penicillium chrysogenum (the industrial penicillin producer). However, A. nidulans and P. chrysogenum are close in terms of their phylogeny and one can reasonably predict that the conclusions about A. nidulans, which are summarized in this review and which are of unquestionable biotechnological relevance, will be extrapolable to the industrial organism.
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    URL: http://dx.doi.org/10.1007/BF00328034
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    Interaction of dichloromethane (methylene chloride) with the nitrous oxide reductase from Wolinella succinogenes (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 479-482 
    Details
    ISSN: 1573-0972
    Keywords: Benzyl viologen ; dichloromethane ; inhibitor ; kinetics ; nitrous oxide ; nitrous oxide reductase ; tetrachloromethane ; trichloromethane ; Wolinella succinogenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Nitrous oxide reductase from Wolinella succinogenes was tested for benzyl viologen cation (BV+)-chlorinated methane oxidoreductase activity, using di-, tri- and tetra-chloromethanes, and for the inhibition of BV+-N2O oxidoreductase activity by these chloromethanes. No BV+-chlorinated methane oxidoreductase activity was detected. Any such activity, if it exists, must be less than 0.1% of the BV+-N2O oxidoreductase activity of the enzyme. Inhibition of the BV+-N2O oxidoreductase activity by dichloromethane was detected and was apparently reversible and non-competitive, as is the case with the small metal-ligand type inhibitors of the enzyme (e.g. acettlene, azide, cyanide and carbon monoxide). Trichloromethane was a weaker inhibitor and inhibition was not detected with tetrachloromethane.
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    URL: http://dx.doi.org/10.1007/BF00328037
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    The effect of thyroid hormones and 5-azacytidine on transcription of malic enzyme and 6-phosphogluconate dehydrogenase genes (1993)
    Springer
    Bulletin of experimental biology and medicine 116 (1993), S. 1376-1378 
    Details
    ISSN: 1573-8221
    Keywords: DNA methylase ; gene expression ; thyroid hormones ; 5-azacytidine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00805150
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