THE DOSE RESPONSE CURVE IN PHYTOCHROME-MEDIATED ANTHOCYANIN SYNTHESIS IN THE MUSTARD SEEDLING

Abstract —The dose response curve for light (phytochrome)-induced anthocyanin synthesis was determined in the mustard seedling. The curve gives the amount of anthocyanin (A) synthesized within 24 h as a function of the amount of P_fr* produced by a brief light pulse. The [P_fr] response curve is composed of two linear parts with very different slopes ( a _1,2) connected by a relatively narrow transient range (curved segment). The [P_fr] response curve extrapolates precisely through zero [P_fr]. The reciprocity law is valid over the whole range investigated (up to 320 s of irradiation). It is concluded that the initial (or primary) reaction of P_fr (P_fr+ X → P_frX) does not involve any significant cooperativity in the case of phytochrome-mediated anthocyanin synthesis. It is speculated that the linear parts of the [P_fr] response curve truly reflect the mode of phytochrome action ( A = a _1,2 [P_fr]; X does not come into play since it is not rate limiting) whereas the curved segment represents a transition of the reaction matrix of P_fr. The large difference between a₁ and a₂ seems to indicate that the physiological effectiveness of a given amount of P_fr (or P_frX) is determined by [P_fr] through a P_fr-induced change in the reaction matrix.     

Experimental limits on the strength of weak neutral currents in lepton pair production at PETRA energies

The processes e⁺e^? → e⁺e^? and μ⁺μ^? have been studied at PETRA using the JADE detector. The data, which were collected at s-values of up to 1300 GeV² have been analysed in terms of an electro-weak extension of QED to obtain values for the weak vector and axial vector couplings in the lepton sector. The values obtained agree with the predictions of the standard Salam-Weinberg model and the data are further analysed in terms of this model to obtain the limits 0.10 < sin²?_w < 0.40 (68% CL). The mass of the neutral weak gauge boson is deduced to be greater than 51 GeV/c².     

Synthesis and structures of cyclic gold complexes containing diphosphine ligands and luminescent properties of the high nuclearity species

A mixture of cyclic gold(I) complexes [Au(2)(μ-cis-dppen)(2)]X(2) (X = OTf 1, PF(6)3) and [Au(cis-dppen)(2)]X (X = OTf 2, PF(6)4) is obtained from the reaction of [Au(tht)(2)]X (tht = tetrahydrothiophene) with one equivalent of cis-dppen [dppen = 1,2-bis(diphenylphosphino)ethylene]. The analogous reaction with trans-dppen or dppa [dppa = bis(diphenylphosphino)acetylene] affords the cyclic trinuclear [Au(3)(μ-trans-dppen)(3)]X(3) (X = OTf 11, PF(6)12) and tetranuclear [Au(4)(μ-dppa)(4)]X(4) (X = OTf 13, PF(6)14, ClO(4)15) gold complexes, respectively. Recrystallization of 15 from CH(2)Cl(2)/MeOH yielded a crystal of the octanuclear gold cluster [Au(8)Cl(2)(μ-dppa)(4)](ClO(4))(2)16. Attempts to prepare dicationic binuclear gold(II) species from the reaction of a mixture of 3 and 4 with halogens gave a mixture of products, the components of which confirmed to be acyclic binuclear gold(I) [Au(2)X(2)(cis-dppen)] (X = I 5, Br 7) and cyclic mononuclear gold(III) [AuX(2)(cis-dppen)]PF(6) (X = I 6, Br 8) complexes. Complexes 11-14 reveal weak emission in butyronitrile glass at 77 K, but they are non-emissive at room temperature. Ab initio modelling was performed to determine the charge state of the gold atoms involved. Extensive structural comparisons were made to experimental data to benchmark these calculations and rationalize the conformations.     

Closed time-like curves in flat Lorentz space–times

We consider the region of closed time-like curves (CTCs) in three-dimensional flat Lorentz space–times. The interest in this global geometrical feature goes beyond the purely mathematical one. Such space–times are lower-dimensional toy models of sourceless Einstein gravity or cosmology. In three dimensions all such space–times are known: they are quotients of Minkowski space by a suitable group of Poincaré isometries. The presence of CTCs would indicate the possibility of “time machines”, a region of space–time where an object can travel along in time and revisit the same event. Such space–times also provide a testbed for the chronology protection conjecture, which suggests that quantum back reaction would eliminate CTCs. In particular, our interest in this note will be to find the set free of CTCs for , where is modeled on Minkowski space and γ is a Poincaré transformation. We describe the set free of CTCs where γ is hyperbolic, parabolic, and elliptic.     

Equidistant hypersurfaces of the bidisk

The following are notes on the geometry of the bidisk, H ² × H ². In particular, we examine the properties of equidistant surfaces in the bidisk.     

The mass and low-lying levels of 40Cl

The mass excess of the T_z = 3 nucleus ⁴⁰Cl has been determined using the ⁴⁰Ar(⁷Li, ⁷Be)⁴⁰Cl reaction. A value ?27.527 ± 0.035 MeV was obtained. A number of excited states of ⁴⁰Cl were a1so observed. In addition, the ⁴⁰Ar(¹¹B, ¹¹C)⁴⁰Cl and ⁴⁰Ar(¹¹B, ¹³N)³⁸S reactions were investigated. Excited states of ³⁸S were observed at 1.28 ± 0.04 and 3.38 ± 0.10 MeV.     

Ebene absolute geometrie über Euklidischen Körpern

We give a set of seven postulates for plane absolute geometry based on the geometric notions points and lines and show that every absolute plane is — up to isomorphisms — either a Euclidean or a hyperbolic plane over a Euclidean field.     

THE MODE OF INTERACTION BETWEEN BLUE (UV) LIGHT PHOTORECEPTOR AND PHYTOCHROME IN ANTHOCYANIN FORMATION OF THE SORGHUM SEEDLING

Two non-photosynthetic photoreceptors (phytochrome and a blue light photoreceptor) are involved in light-mediated anthocyanin synthesis in the mesocotyl of Sorghum seedlings. The present study was undertaken to investigate the kind of interaction between phytochrome and the blue light photoreceptor. The data show that phytochrome (P_fr) can only act once a blue light effect has occurred. On the other hand, the blue light effect cannot express itself without P_fr. It is concluded that there is an obligatory dependency (or sequential interaction) between the blue light effect and the light effect occurring through phytochrome, although the blue light photoreaction per se is not affected by the presence or absence of phytochrome. The latter statement is based on the results of dichromatic experiments, i.e. simultaneous, high fluence rate irradiation with two kinds of light. Blue light can be replaced by UV light. It is not clarified yet whether the effect of blue and UV light is due to the same photoreceptor.