A chiral photoswitch based on enantiospecific interconversion between binaphthyl and helicenoid skeletons.

A novel chiral photoswitch composed of a binaphthyl unit and a hexafluorocyclopentene ring has been synthesized. This chiral photoswitch exhibited thermally reversible photochromism between the binaphthyl and helicenoid forms based on 6π-electrocyclization. The helicity of the binaphthyl moiety was reversed upon stereospecific photocyclization and reverted back during the thermal ring opening.

Phytochrome A requires jasmonate for photodestruction.

The plant photoreceptor phytochrome is organised in a small gene family with phytochrome A (phyA) being unique, because it is specifically degraded upon activation by light. This so called photodestruction is thought to be important for dynamic aspects of sensing such as measuring day length or shading by competitors. Signal-triggered proteolytic degradation has emerged as central element of signal crosstalk in plants during recent years, but many of the molecular players are still unknown. We therefore analyzed a jasmonate (JA)-deficient rice mutant, hebiba, that in several aspects resembles a mutant affected in photomorphogenesis. In this mutant, the photodestruction of phyA is delayed as shown by in vivo spectroscopy and Western blot analysis. Application of methyl-JA (MeJA) can rescue the delayed phyA photodestruction in the mutant in a time- and dose-dependent manner. Light regulation of phyA transcripts thought to be under control of stable phytochrome B (phyB) is still functional. The delayed photodestruction is accompanied by an elevated sensitivity of phytochrome-dependent growth responses to red and far-red light.

Corrigendum: Collocated observations of cloud condensation nuclei, particle size distributions, and chemical composition.

This corrects the article DOI: 10.1038/sdata.2017.3.

Collocated observations of cloud condensation nuclei, particle size distributions, and chemical composition.

Cloud condensation nuclei (CCN) number concentrations alongside with submicrometer particle number size distributions and particle chemical composition have been measured at atmospheric observatories of the Aerosols, Clouds, and Trace gases Research InfraStructure (ACTRIS) as well as other international sites over multiple years. Here, harmonized data records from 11 observatories are summarized, spanning 98,677 instrument hours for CCN data, 157,880 for particle number size distributions, and 70,817 for chemical composition data. The observatories represent nine different environments, e.g., Arctic, Atlantic, Pacific and Mediterranean maritime, boreal forest, or high alpine atmospheric conditions. This is a unique collection of aerosol particle properties most relevant for studying aerosol-cloud interactions which constitute the largest uncertainty in anthropogenic radiative forcing of the climate. The dataset is appropriate for comprehensive aerosol characterization (e.g., closure studies of CCN), model-measurement intercomparison and satellite retrieval method evaluation, among others. Data have been acquired and processed following international recommendations for quality assurance and have undergone multiple stages of quality assessment.

Three redundant brassinosteroid early response genes encode putative bHLH transcription factors required for normal growth.

Brassinosteroids (BRs) are a class of polyhydroxylated steroids that are important regulators of plant growth and development. We have identified three closely related basic helix-loop-helix (bHLH) transcription factors, BEE1, BEE2, and BEE3, as products of early response genes required for full BR response. Comparison of the phenotypes of plants that overexpress BEE1 with bee1 bee2 bee3 triple-knockout mutant plants suggests that BEE1, BEE2, and BEE3 are functionally redundant positive regulators of BR signaling. Expression of BEE1, BEE2, and BEE3 is also regulated by other hormones, notably abscisic acid (ABA), a known antagonist of BR signaling. Reduced ABA response in plants overexpressing BEE1 suggests that BEE proteins may function as signaling intermediates in multiple pathways.

EFFECT OF CENTRIFUGATION ON THE DEVELOPMENT AND TIMING OF PREMITOTIC POSITIONING OF THE NUCLEUS IN ADIANTUM PROTONEMATA.

When single-celled protonemata of Adiantum capillus-veneris L. were centrifuged immediately before transferring to darkness from continuous irradiation with red light, their nuclei were displaced basipetally. Both filamentous and branched protonemata were obtained. The stronger the centrifugal acceleration, the more frequently the branched protonemata were induced. The effect of centrifugation at 1,300 x g for 15 min on nuclear displacement was different at different stages of the cell cycle. In early G1 phase, the nucleus was easily displaced by centrifugation, but quickly returned to the original position after centrifugation. In late G1 phase, the nucleus was displaced, but after centrifugation it never came back to the original position. In late G2 and M phases, the nucleus was no longer displaced by the centrifugation. Premitotic positioning of the nucleus in cytokinesis took place about 5 hr before cell plate formation in all centrifugal treatments described above.

BIOASSAY OF ANTHERIDIOGEN IN LYGODIUM JAPONICUM.

Antheridia were induced by exogenously applied GA3 at concentrations between 10-6 and 3 × 10-4 M in very young filamentous protonemata of Lygodium japonicum grown in darkness; the longer the dark preculture of protonemata, the lower was the sensitivity of the protonemata to GA3 . Antheridial initials were discernible after 36 hr of GA3 treatment in the most sensitive protonemata, and the timing of antheridial initiation was delayed with increasing protonemal age. This quantitative response of the protonemata provided the basis for a new method of assaying gibberellins in terms of the degree of antheridial formation. According to this method, all the gibberellins tested and one of their precursors were active in inducing antheridia in the protonemata, and the activity spectrum of the gibberellins was as follows: GA7 >GA4 >GA9 >GA3 >GA5 >GA1 >GA8 . The amounts of antheridiogen contained in conditioned media were measured by the present bioassay. A semi-logarithmic relation was shown between the percentage of antheridial formation and the concentration of conditioned medium within a certain dilution range. The amounts of antheridiogen secreted by the prothallia were quantitatively compared by transferring samples onto fresh media for a short period of time.

PHOTOCONTROL OF THE ORIENTATION OF CELL DIVISION IN ADIANTUM. III. EFFECTS OF METABOLIC INHIBITORS.

5-Fluorouracil, 8-azaguanine and ethionine were tested on the orientation of cell division to see whether the two-dimensional development of the fern Adiantum gametophytes was due to newly synthesized protein(s). Using the system in which the orientation of cell division was controlled experimentally by sequential treatment with red light, white light and darkness and by the direction of irradiation, all the inhibitors decreased the rates of cell elongation and cell division of the gametophytes, but did not specifically affect the two-dimensional differentiation at all.

APICAL GROWTH OF PROTONEMATA IN ADIANTUM CAPILLUSVENERIS. I. RED FAR-RED REVERSIBLE EFFECT ON GROWTH CESSATION IN THE DARK.

Apical growth of individual protonemata in Adiantum capillus-veneris was microphotographically observed before, during and after light treatment. When single-celled protonemata precultured under continuous red light were transferred to darkness, the apical growth continued for the next 24 hr at a rate somewhat slower than that under continuous red light, but the rate significantly decreased thereafter and growth ceased within 72 hr in the dark. The growth in the dark was strongly inhibited by a brief irradiation with far-red light given immediately before the dark period, and the effect of far-red light was fully reversed by subsequent red light. This reversibility was repeatedly observed, suggesting the involvement of a phytochrome system. The intracellular localization of the phytochrome system in the protonemata was studied, using a narrow-beam irradiator. The results showed that the photoreceptive sites of far-red light are not localized in any particular region of the cell.

Protein Synthesis during Photocontrolled Progression of the Cell Cycle in Single-celled Protonemata of the Fern Adiantum Capillus-veneris: (cell cycle/fern (Adiantum)/photocontrol/protein synthesis/protonema).

Protein synthesis during photoinduced, synchronous progression of the cell cycle in single-celled protonemata of the fern Adiantum capillus-veneris was studied by tracer techniques. Nuclei of the protonemata were labelled with 3 H-thymidine during spore germination so that the amount of 3 H incorporated into the TCA-insoluble fraction of the cells could be used as a measure of the cell number in each sample. The rate of the incorporation of 14 C-amino acids into TCA-insoluble materials was not significantly varied at different stages of the cell cycle or by treatment with blue light. Extracts of cells labelled with 35 S-methionine at various times after the transfer from red light condition (G0 ) to darkness (G1 to S) were analyzed by two-dimensional gel electrophoresis. At least 3 of about 200 spots showed significant changes in intensity on fluorograms. Spot A (molecular weight 20,000, isoelectric point 6.3) was detectable only in early G1 , whereas spot B (molecular weight 19,500, isoelectric point 6.3) was found only in the late G1 and S phases. When the cells were exposed to blue light before the dark incubation, the times of disappearance of spot A and appearance of spot B were advanced depending upon the progression of the cell cycle but not upon the clock time.

EFFECTS OF PHYTOCHROME AND BLUE-NEAR ULTRAVIOLET LIGHT-ABSORBING PIGMENT ON DURATION OF COMPONENT PHASES OF THE CELL CYCLE IN ADIANTUM GAMETOPHYTES.

Single-celled protonemata of the fern Adiantum capillus-veneris, kept under continuous red light, grew with a very low rate of cell division, and the cell cycle was arrested in the early G1 phase. Cell division was induced by transferring the protonemata to the dark after various light treatments, and the duration of component phases in the cell cycle was determined by a continuous-labelling technique with 3H-thymidine. Blue light irradiation greatly reduced the duration of the G1 phase but did not affect that of other phases. The greater the fluence of blue light, the shorter was the duration of G1 phase was observed. In contrast, a brief exposure of red-light-grown protonemata to far-red light given immediately before the dark incubation showed no effect on the duration of G1 S and M phases but significantly extended that of the G2 phase. The effect of far-red light on the G2 phase was reversed by red light, and the effects of red and far-red light were repeatedly reversible. The progression in the M phase was shown by means of a time-lapse video system to be not at all influenced by any pre-irradiation described above.

EFFECTS OF ENVIRONMENTAL FACTORS ON MECHANICAL PROPERTIES OF THE CELL WALL IN RICE COLEOPTILES.

Cell wall properties determined by the stress-relaxation technique were studied with coleoptiles of rice seedlings grown under different environmental conditions. The cell wall was simulated by a viscoelastic model consisting of either four or an infinite number of Maxwell components. Reciprocal of relaxation time for the first component in the former model (1/τ1 ) and minimum and maximum relaxation times (To and Tm ) in the latter, in addition to the stress/strain ratio, were parameters representing cell wall properties. Parameters changed depending on the ages and regions of the coleoptilles used and 011 the environmental conditions under which rice seedlings were grown. Effects on cell wall properties of aeration during submerged growth, excision of the coleoptile tip, and exposure to small doses of red and/or far-red light were examined. In most cases, high values of 1/τ1 and of Tm and small values of To were consistent with the growth potentiality of cells, while the stress/strain ratio seemed to be a consequence of elongation growth.

Cycloheximide Insensitive Amoebo-Flagellate Transformation in Starved Amoebae of Physarum polycephalum: (Physarum polycephalum/amoebo-flagellate transformation/starvation/cycloheximide/protein synthesis).

The requirement of protein synthesis for amoebo-flagellate transformation of Physarum polycephalum was re-examined. When amoebae were grown on nutrient agar in association with live food bacteria and harvested in mid-exponential phase of growth, it took ca. 2 hours for half the cells to form flagella after suspension in phosphate buffer. The transformation was completely inhibited by 5 µg/ml cycloheximide. To the contrary, when the amoebae in mid-exponential phase were starved for 3 hr on non-nutrient agar and then suspended in phosphate buffer, the duration required for this process was shortened to ca. 8 min and it was not inhibited by up to 100 µg/ml cycloheximide. A similar result was obtained using bactobolin, another inhibitor of protein synthesis. When amoebae were starved on non-nutrient agar containing 5 µg/ml cycloheximide, however, the starvation effect described above was not observed. The results indicate that protein(s) necessary for the transformation might be synthesized during the starvation period, and that the amoebo-flagellate transformation may or may not require concomitant protein synthesis depending upon preculture conditions.

Catalytic synthesis of thiobutyrolactones via CO insertion into the C-S bond of thietanes in the presence of a heterodinuclear organoplatinum-cobalt complex.

Heterodinuclear organoplatinum-cobalt complex having a 1,2-bis(diphenylphosphino)ethane ligand (dppe)MePt-Co(CO)4 catalyzes CO insertion into the C-S bond of thietanes in THF at 100 degrees C under 1.0 MPa of CO for 2 h to give gamma-thiobutyrolactone in quantitative yield.

Long and short term QT-RR interval co-variability in type 2 diabetes.

This paper examines the long and short term co-variability of QT and RR intervals for diabetic patients to explore if the QT-RR co-variability could yield a noble index for the stratification of clinical severity of the disease. Twenty four hour Holter ECG recordings are made for 19 type 2 diabetic (T2DM) patients and 25 normal subjects. RR and QT intervals are extracted from ECG signals sampled at 200 Hz and their co-variability has been examined. To see the long term QT-RR co-variability, correlation coefficients and mutual entropies between QT and RR intervals have been estimated for original beat to beat intervals and smoothed median interval series of successive one hundred beats. Mutual entropy for both beat-to-beat and smoothed median QT and RR interval series showed statistically significant differences between T2DM and control subjects whereas differences in correlation coefficients showed significant difference only for beat-to-beat intervals. Mutual entropy between both beat-to-beat and smoothed median QT-RR interval sequences showed the equally well separation between T2DM patients and control subjects: Mutual entropy and serial correlation coefficients for beat to beat intervals are respectively 1.42 ± 0.33 (bits), 0.856 ± 0.055 for control and 0.752 ± 0.23 (bits), 0.756 ± 0.10 for T2DM patients. Scatter diagram between RR and QT intervals show apparent nonlinearity which validate this result. Short term QT-RR co-variability has been examined by spline smoothed QTc series and sporadic changes have been observed for the control subjects whereas no such changes are found in diabetic patients. This new phenomenon could be a mean for the clinical characterization of diabetes.

A rice phytochrome A in Arabidopsis: The Role of the N-terminus under red and far-red light.

The phytochrome (phy)A and phyB photoreceptors mediate three photobiological response modes in plants; whereas phyA can mediate the very-low-fluence response (VLFR), the high-irradiance response (HIR) and, to some extent, the low fluence response (LFR), phyB and other type II phytochromes only mediate the LFR. To investigate to what level a rice phyA can complement for Arabidopsis phyA or phyB function and to evaluate the role of the serine residues in the first 20 amino acids of the N-terminus of phyA, we examined VLFR, LFR, and HIR responses in phyB and phyAphyB mutant plants transformed with rice PHYA cDNA or a mutant rice PHYA cDNA in which the first 10 serine residues were mutated to alanines (phyA SA). Utilizing mutants without endogenous phyB allowed the evaluation of red-light-derived responses sensed by the rice phyA. In summary, the WT rice phyA could complement VLFR and LFR responses such as inhibition of hypocotyl elongation under pulses of FR or continuous R light, induction of flowering and leaf expansion, whereas the phyA SA was more specific for HIR responses (e.g. inhibition of hypocotyl elongation and anthocyanin accumulation under continuous far-red light). As the N-terminal serines can no longer be phosphorylated in the phyA SA mutant, this suggests a role for phosphorylation discriminating between the different phyA-dependent responses. The efficacy of the rice phyA expressed in Arabidopsis was dependent upon the developmental age of the plants analyzed and on the physiological response, suggesting a stage-dependent downstream modulation of phytochrome signaling.

Identification and characterization of pin and thrum alleles of two genes that co-segregate with the Primula S locus.

The study of heteromorphy in Primula over the past 140 years has established the reproductive significance of this breeding system. Plants produce either thrum or pin flowers that demonstrate reciprocal herkogamy. Thrums have short styles and produce large pollen from anthers at the mouth of the flower; pins have long styles and produce small pollen from anthers located within the corolla tube. The control of heteromorphy is orchestrated by the S locus with dominant (S) and recessive (s) alleles that comprise a co-adapted linkage group of genes. Thrum plants are heterozygous (Ss) and pin plants are homozygous (ss). Reciprocal crosses between the two forms are required for fertilization; within-morph crosses are impeded by a sporophytic self-incompatibility system. Rare recombination events within the S locus produce self-fertile homostyles. As a first step towards identifying genes located at the S locus, we used fluorescent differential display to screen for differential gene expression in pin and thrum flowers. Rather than only detecting differentially regulated genes, we identified two S locus linked genes by virtue of allelic variation between pin and thrum transcripts. Analysis of pin and thrum plants together with homostyle recombinant reveals that one gene flanks the locus, whereas the other shows complete linkage. One gene is related to Arabidopsis flower-timing genes Col9 and Col10; the other encodes a small predicted membrane protein of unknown function. Notwithstanding the diallelic behaviour of the Primula S locus, analysis of pin and thrum plants reveal three alleles for each gene: two pin and one thrum.