SPECIFIC PROTEIN OCCURRENCE RELATED WITH PHOTOPERIODIC FLOWER INDUCTION IN THE COTYLEDONS OF Pharbitis nil CV. VIOLET

In our experiment, three groups of seedlings of SDP Pharbitis nil cv. violet were sepa-rately treated with three different photoperiods (1,16 h dark period--SD; 2, continuous illumi-nation--CL; 3, 16 h dark treatment with 10 min white light in the middle of the dark period--NB). By analysing proteins in the cotyledons from three groups with 2-D PAGE, we found nodifference in protein pattern between the three groups at 0 or 8 h after photoperiodic treatments.At 24 h after the treatments, a specific protein(MW:19 kD; pI: 4.5)appeared only in the cotyledonsof the seedlings which endured SD. This protein disappeared at 72 h after SD. ActinomycinD could inhibit flowering and the specific protein occurrence when applied to cotyledonsprior to SD, but it had no inhibition effect on flowering as well as the specific proteinoccurrence when applied to cotyledons after SD. Chloroamphenicol, a protein synthesisinhibitor, inhibited flowering when applied to cotyledons prior to or immediately after SD,but it did not i     

CHARACTERIZATION OF THE 32,000 DALTON MEMBRANE PROTEIN—I. EARLY SYNTHESIS DURING PHOTOINDUCED PLASTID DEVELOPMENT OF SPIRODELA

The kinetics of ³⁵S methionine incorporation into soluble and membrane proteins during the transition from steady state dark growth to greening was studied in Spirodela. A sharp increase in the rate of incorporation occurred at 3 h, which was several h before major increases in chlorophyll were apparent. Part of this enhanced incorporation was due to enhanced synthesis of a 32 ,000 dalton membrane protein. This synthesis was paralleled by a temporal increase in in uitro template capacity for this protein and an increase in 0.5 × 10⁶ dalton plastid messenger RNA.     

Distribution of type I phytochrome (phyA) RNA1 and RNA2 in etiolated pea seedlings.

Four-day-old etiolated pea seedlings were divided into 11 parts along the axis, from which poly(A)+ RNA and DNA were extracted. Using a slot-blot hybridization assay, the abundance of pea type I phytochrome (phyA) poly(A)+ RNA was measured in each portion of the etiolated pea seedling. For the quantification of the phyA RNA, pea phyA RNA synthesized in vitro was used as an RNA standard. The hook region contained the highest abundance of phyA RNA (approximately 0.3 ng phyA RNA per microgram DNA) in the etiolated seedling. Two mRNAs of different length (the shorter designated as RNA1 and the longer RNA2) are produced in detectable amounts from single pea phyA in the etiolated seedling; the ratio of the abundance of phyA RNA1 to phyA RNA2 was determined in each of the 11 parts by a primer extension assay. The abundance of phyA RNA1 in the plumule and hook regions was 3-5-fold higher than that of RNA2, whereas the ratio of their abundance was approximately unity in other regions. A time course study of the abundance of both RNAs was carried out during the imbibition of seeds and indicated that the accumulation of phyA RNA1 occurred more rapidly in the cotyledons than that of RNA2 during the first day of imbibition, whereas the accumulation of phyA RNA2 increased rapidly during the second day and became as high as that of phyA RNA1 by the third day.     

THE PHOTOPERIODIC CONTROL OF FLOWERING: PROGRESS TOWARD UNDERSTANDING THE MECHANISM OF INDUCTION

The mechanism of photoperiodic flower induction remains a major unsolved problem in plant development. Although it is firmly established that phytochrome is the primary photoreceptor in photoperiodic responses including flowering, the intermediate processes of induction including signal transduction, biochemistry of the induced state, and synthesis and identification of the floral stimulus are still obscure. In this review, advances in key areas of research that have contributed to our understanding of photoperiodic flower induction are discussed. These include the role of phytochrome in photoperiodic flowering, physiological characterization of the photoperiodic flowering response, the mechanism of photoperiodic time measurement during induction, and the nature of flower-promoting and flower-inhibiting substances. Finally, the role of alterations in gene expression in mediating photoperiodic flower induction is considered along with emerging opportunities for future research that may increase our understanding of the mechanism of flower induction.     

INHIBITORY EFFECT OF CONTINUOUS FAR-RED PREIRRADIATION ON CHLOROPHYLL ACCUMULATION OF PHARBITIS NIL COTYLEDONS

Abstract The effect of continuous far-red (FR) preirradiation on the accumulation of chlorophyll (Chi) during a white light (WL; 500 lx) period was examined using Pharbitis nil cotyledons. The saturation level of accumulated Chi attained after prolonged exposure to WL was always lowered by continuous FR irradiation preceding the WL. The rate of Chi accumulation during the rapid increase phase (operationally defined as the amount of Chi accumulated during a 24-h WL period) was enhanced by preirradiation with up to 36 h of FR. However, when the FR preirradiation lasted longer, the rate was reduced below the dark control level. Even FR preirradiation of up to 36 h fully reduced the rate of Chi accumulation under WL when 36 h or longer darkness was spaced between the FR and the WL period.     

MONOCLONAL ANTIBODY WITH SPECIFIC AFFINITY FOR PYRIMIDINE DIMERS IN RNA

Abstract— A monoclonal antibody was prepared which meets three criteria for specific binding to pyrimidine dimers in RNA. (i) UV irradiation at wavelengths greater than 300 nm in the presence of a triplet state sensitizer, or at 270 nm without sensitizer, promotes antibody binding to RNA and polyribonucleotides, (ii) Antibody binding is reduced by exposure to UV radiation of short wavelength (240 nm) following sensitized irradiation (<300 nm). (iii) Antibody binding is dependent upon the presence of adjacent pyrimidine ribonucleotides. The antibody recognizes a single uridine dimer with one or more additional nucleotides at both ends. Affinity for a single uridine dimer with additional nucleotides at only the 3' end is substantially weaker.     

SPS-B, a physiological sleep regulator, from the brainstems of sleep-deprived rats, identified as oxidized glutathione

We previously reported regarding the "sleep-promoting substance (SPS)," which was isolated from the brainstem extract of sleep-deprived rats, the existence of multiple active components including uridine and SPS-B. Intracerebroventricular infusion of crude SPS-B exhibited significant enhancing effects on both slow wave sleep and paradoxical sleep in unrestrained rats. Further investigation of SPS-B has resulted in its final identification as oxidized glutathione (GSSG, gamma-glutamylcysteinylglycine disulfide). Authentic GSSG similarly administered in rats also significantly enhanced sleep which was indistinguishable from normal physiological sleep. We propose GSSG as a candidate endogenous sleep substance.     

Synthesis and hybridization properties of 2'-O-methylated oligoribonucleotides incorporating 2'-O-naphthyluridines

2'-O-(1-Naphthyl)uridine and 2'-O-(2-naphthyl)uridine were synthesized by a microwave-mediated reaction of 2,2'-anhydrouridine with naphthols. Using the 3'-phosphoramidite building blocks, these 2'-O-aryluridine derivatives were incorporated into 2'-O-methylated oligoribonucleotides. Incorporation of five 2'-O-(2-naphthyl)uridines into a 2'-O-methylated RNA sense strand significantly increased the thermostability of the duplex with a 2'-O-methylated RNA antisense strand. Circular dichroism spectroscopy and molecular dynamic simulation of the duplexes formed between the modified RNAs and 2'-O-methyl RNAs suggested that there are π-π interactions between two neighboring naphthyl groups in a sequence of the five consecutively modified nucleosides.     

RHYTHMIC OSCILLATION OF CYCLIC 3',5'AMP AND -GMP CONCENTRATION AND STIMULATION OF FLOWERING BY CYCLIC 3',5'-GMP IN Lemna paucicostata 381

Abstract— Rhythmic oscillation of the concentration of cyclic 3',5'-AMP and -GMP in a short day plant, Lemna paucicostata 381 in continuous darkness was detected after 2 cycles of 12 h dark and 12 h light entrainment. Cyclic 3',5'-AMP and -GMP, extracted from whole plant showed parallel oscillations in their concentrations for initial 36 h in continuous darkness and the oscillation in the concentration of cyclic 3',5'-AMP was roughly circadian. Their concentrations decreased during the initial 12 h (subjective night) and increased during 12 to 28 h. Exogenous addition of 2 μ.M of cyclic 3',5'-GMP or the dibutyryl derivative of it stimulated floral induction by 20 to 30%, when the plants were grown under 12 h light and 12 h dark regime. Cyclic 3',5'-AMP or the dibutyryl derivative of it showed little effect on flowering.     

Field-free molecular orientation enhanced by two dual-color laser subpulses

In this paper, we theoretically show that the field-free molecular orientation created by a single dual-color laser pulse can be significantly enhanced by separating it into two time-delayed dual-color subpulses. It is indicated that the maximum enhancement of the molecular orientation created by two time-delayed dual-color subpulses can be achieved with their intensity ratio of about 1:2 and by simultaneously applying the second one at the beginning of the rotational wave packet rephasing or the end of the rotational wave packet dephasing induced by the first one. It is also shown that the enhancement or suppression of the molecular orientation can be coherently manipulated by varying the relative phase between the fundamental field and its second harmonic field of the second dual-color subpulse, and its enhancement is obtained around half rotational period.     

冲击波处理结晶氧化镁的催化性能研究

冲击波处理结晶氧化镁的催化性能研究１）刘建军徐康２）（中国科学院兰州化学物理研究所兰州７３００００）贺红亮谭华（西南流体物理研究所冲击波物理与爆轰物理实验室成都６１０００３）张菊郑小明（杭州大学催化研究所杭州３１００２８）关键词冲击波氧化镁ＴＰＤＥＳ...     

Synthesis of uridine 5'-diphosphoiduronic acid: a potential substrate for the chemoenzymatic synthesis of heparin

An improved understanding of the biological activities of heparin requires structurally defined heparin oligosaccharides. The chemoenzymatic synthesis of heparin oligosaccharides relies on glycosyltransferases that use UDP-sugar nucleotides as donors. Uridine 5'-diphosphoiduronic acid (UDP-IdoA) and uridine 5'-diphosphohexenuronic acid (UDP-HexUA) have been synthesized as potential analogues of uridine 5'-diphosphoglucuronic acid (UDP-GlcA) for enzymatic incorporation into heparin oligosaccharides. Non-natural UDP-IdoA and UDP-HexUA were tested as substrates for various glucuronosyltransferases to better understand enzyme specificity.     

Responses of Bruguiera gymnorrhiza to saltwater monitored by miniature electrodes

We measured the voltage between two Ag/AgCl electrodes, one inserted into the seedling of the salt-tolerant plant Bruguiera gymnorrhiza and the other into the vermiculite in which the seedling was potted. Four seedlings were placed in different environments, in saltwater or pure water, with light or alternating light/dark conditions. We have found that (1) the voltage profiles showed periodical oscillatory behavior; (2) seedlings in saltwater showed higher voltage compared to the ones in pure water; (3) in the light environment, the voltage was higher compared to the one in the dark environment; (4) in the dark environment, a voltage wave was hardly observable; and (5) electrodes inserted into the propagule cortex, stem cortex, and petiole showed different voltage wave amplitudes. The voltage profiles will provide an effective way to evaluate the movement of salt water inside the salt-tolerant plant.     

Atomistic molecular dynamics simulations of shock compressed quartz

Atomistic non-equilibrium molecular dynamics simulations of shock wave compression of quartz have been performed using the so-called BKS semi-empirical potential of van Beest, Kramer, and van Santen [Phys. Rev. B 43, 5068 (1991)] to construct the Hugoniot of quartz. Our scheme mimics the real world experimental set up by using a flyer-plate impactor to initiate the shock wave and is the first shock wave simulation that uses a geometry optimised system of a polar slab in a three-dimensional system employing periodic boundary conditions. Our scheme also includes the relaxation of the surface dipole in the polar quartz slab which is an essential pre-requisite to a stable simulation. The original BKS potential is unsuited to shock wave calculations and so we propose a simple modification. With this modification, we find that our calculated Hugoniot is in good agreement with experimental shock wave data up to 25 GPa, but significantly diverges beyond this point. We conclude that our modified BKS potential is suitable for quartz under representative pressure conditions of the Earth core, but unsuitable for high-pressure shock wave simulations. We also find that the BKS potential incorrectly prefers the β-quartz phase over the α-quartz phase at zero-temperature, and that there is a β → α phase-transition at 6 GPa.     

Effect of preillumination on photomotile responses of the marine ciliate Fabrea salina

Fabrea salina is a marine ciliate that shows photomotile responses such as positive phototaxis and a step-down photophobic reaction. We found that preilluminated F. salina cells show a phototactic response significantly greater than that of dark-adapted cells when exposed to the same phototactic light stimulus. In particular, positive phototaxis is strongly enhanced by preillumination. This enhancement effect depends on the preillumination light irradiance, on the total preillumination dose, and on the duration of the dark interval between preillumination and the phototaxis measurement. Our results show that the determining factor is the total preillumination dose given to the sample. The enhancement effect shows an asymptotic behavior over a certain range of energy values (10-200 W/m2). Further, the effect is transient; after 120 s in the dark, the cells lose any memory of the preillumination, independent of the preillumination energy received. These results are tentatively discussed in terms of light-driven membrane potential or membrane channel conductances.     

Synthesis of (6-(13)C)pyrimidine nucleotides as spin-labels for RNA dynamics

We present a (13)C-based isotope labeling protocol for RNA. Using (6-(13)C)pyrimidine phosphoramidite building blocks, site-specific labels can be incorporated into a target RNA via chemical oligonucleotide solid-phase synthesis. This labeling scheme is particularly useful for studying milli- to microsecond dynamics via NMR spectroscopy, as an isolated spin system is a crucial prerequisite to apply Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion type experiments. We demonstrate the applicability for the characterization and detection of functional dynamics on various time scales by incorporating the (6-(13)C)uridine and -cytidine labels into biologically relevant RNAs. The refolding kinetics of a bistable terminator antiterminator segment involved in the gene regulation process controlled by the preQ(1) riboswitch class I was investigated. Using (13)C CPMG relaxation dispersion NMR spectroscopy, the milli- to microsecond dynamics of the HIV-1 transactivation response element RNA and the Varkud satellite stem loop V motif was addressed.