A rainbow of possibilities: A porous polymer gel undergoes light‐triggered rapid two‐state switching between two arbitrary structural colors at a controlled temperature (see picture; “on”: upon UV irradiation, “off”: in the dark). This switching is attributed to a change between two volume states. As the temperature also contributes to the degree of swelling of the gel, the color of the gel can be tuned thermally over a wide range of wavelengths.

The alteration of photoperiod sensitivity has let breeders diversify flowering time in Oryza sativa (rice) and develop cultivars adjusted to a range of growing season periods. Map-based cloning revealed that the rice flowering-time quantitative trait locus (QTL) Heading date 16 (Hd16) encodes a casein kinase-I protein. One non-synonymous substitution in Hd16 resulted in decreased photoperiod sensitivity in rice, and this substitution occurred naturally in an old rice cultivar. By using near-isogenic lines with functional or deficient alleles of several rice flowering-time genes, we observed significant digenetic interactions between Hd16 and four other flowering-time genes (Ghd7, Hd1, DTH8 and Hd2). In a near-isogenic line with the weak-photoperiod-sensitivity allele of Hd16, transcription levels of Ehd1, Hd3a, and RFT1 increased under long-day conditions, and transcription levels of Hd3a and RFT1 decreased under short-day conditions. Expression analysis under continuous light and dark conditions showed that Hd16 was not likely to be associated with circadian clock regulation. Biochemical characterization indicated that the functional Hd16 recombinant protein specifically phosphorylated Ghd7. These results demonstrate that Hd16 acts as an inhibitor in the rice flowering pathway by enhancing the photoperiod response as a result of the phosphorylation of Ghd7.

Recent research into the flowering of rice (Oryza sativa) has revealed both unique and conserved genetic pathways in the photoperiodic control of flowering compared with those in Arabidopsis (Arabidopsis thaliana). We discovered an early heading date2 (ehd2) mutant that shows extremely late flowering under both short- and long-day conditions in line with a background deficient in Heading date1 (Hd1), a rice CONSTANS ortholog that belongs to the conserved pathway. This phenotype in the ehd2 mutants suggests that Ehd2 is pivotal for the floral transition in rice. Map-based cloning revealed that Ehd2 encodes a putative transcription factor with zinc finger motifs orthologous to the INDETERMINATE1 (ID1) gene, which promotes flowering in maize (Zea mays). Ehd2 mRNA in rice tissues accumulated most abundantly in developing leaves, but was present at very low levels around the shoot apex and in roots, patterns that are similar to those of ID1. To assign the position of Ehd2 within the flowering pathway of rice, we compared transcript levels of previously isolated flowering-time genes, such as Ehd1, a member of the unique pathway, Hd3a, and Rice FT-like1 (RFT1; rice florigens), between the wild-type plants and the ehd2 mutants. Severely reduced expression of these genes in ehd2 under both short- and long-day conditions suggests that Ehd2 acts as a flowering promoter mainly by up-regulating Ehd1 and by up-regulating the downstream Hd3a and RFT1 genes in the unique genetic network of photoperiodic flowering in rice.

Two paradigm shifts in DNA sequencing technologies—from bulk to single molecules and from optical to electrical detection—are expected to realize label-free, low-cost DNA sequencing that does not require PCR amplification. It will lead to development of high-throughput third-generation sequencing technologies for personalized medicine. Although nanopore devices have been proposed as third-generation DNA-sequencing devices, a significant milestone in these technologies has been attained by demonstrating a novel technique for resequencing DNA using electrical signals. Here we report single-molecule electrical resequencing of DNA and RNA using a hybrid method of identifying single-base molecules via tunneling currents and random sequencing. Our method reads sequences of nine types of DNA oligomers. The complete sequence of 5′-UGAGGUA-3′ from the let-7 microRNA family was also identified by creating a composite of overlapping fragment sequences, which was randomly determined using tunneling current conducted by single-base molecules as they passed between a pair of nanoelectrodes.

It is well-known that a noble metal nanoparticle (NP) exhibits a color due to light absorption and scattering in the visible region based on plasmon resonance. [1][2][3][4] The resonance wavelength depends on the particle size and shape, the refractive index of the surrounding medium, and the interparticle spacing. [5][6][7][8] The resonance and the resultant colors provide various potential applications such as drawing materials, [9,10] colorimetric sensors, [11,12a] optical filters, [13] nonlinear optical materials, [14] and photovoltaic devices.[15] Recently, we have found that a nanoporous TiO 2 film loaded with Ag NPs exhibits multicolor photochromism only in the presence of O 2 .[9]The color of the film changes under a monochromatic visible light from initial brownish-gray to almost the same color as that of the incident light, because the absorption of the film decreases at around the excitation wavelength, and the color reverts to brownish-gray upon UV irradiation. Although it is reasonable to ascribe the spectral change to morphological changes of the Ag NPs, direct observation of the changes occurring in the nanoporous TiO 2 under the existence of O 2 is difficult. Actually, there have only been some discussions about the morphological changes on the basis of indirect measurements [16] or a theoretical analysis, [17] which are not correlated to the multicolor spectral changes. In this work, we found that even Ag NPs photocatalytically deposited on rutile TiO 2 single crystals exhibit multicolor photochromism, and that size-selective dissolution and re-deposition of Ag NPs, which depend on the excitation wavelength, cause the multicolor spectral changes. These findings provide a new methodology, the photoelectrochemical control of size distribution and color of Ag NPs. The TiO 2 (111) surface was irradiated with UV light using a Hg-Xe lamp (Luminar Ace LA-310UV, Hayashi Watch Works) with a bandpass filter (310 nm; FWHM, 10 nm; ∼ 1.0 mW cm -2 ) in a mixture of aqueous 1 M AgNO 3 and ethanol (1:1 by vol.) to drive photocatalytic [18] deposition of Ag NPs and oxidation of water and/or ethanol.[19] Figure 1a shows the changes of the extinction (i.e., absorption + scattering) spectrum during the deposition. Corresponding AFM images and lateral diameter histograms of the Ag NPs are shown in Figure 2. In the beginning of the deposition (e.g., at 15 s), a broad extinction peak, typical of plasmon resonance of Ag NPs, was observed at ∼ 480 nm. It is reasonable that the peak wavelength (k max ) is longer than the theoretical value [7b,20] (∼ 350 nm) for small Ag NPs in air and shorter than that [7b,20]

Flowering time of rice depends strongly on photoperiodic responses. We previously identified a quantitative trait locus, Heading date 17 (Hd17), that is associated with a difference in flowering time between Japanese rice (Oryza sativa L.) cultivars. Here, we show that the difference may result from a single nucleotide polymorphism within a putative gene that encodes a homolog of the Arabidopsis EARLY FLOWERING 3 protein, which plays important roles in maintaining circadian rhythms. Our results demonstrate that natural variation in Hd17 may change the transcription level of a flowering repressor, Grain number, plant height and heading date 7 (Ghd7), suggesting that Hd17 is part of rice's photoperiodic flowering pathway.

SUMMARYOryza sativa (rice) flowers in response to photoperiod, and is a facultative short-day (SD) plant. Under SD conditions, flowering is promoted through the activation of FT-like genes (rice florigens) by Heading date 1 (Hd1, a rice CONSTANS homolog) and Early heading date 1 (Ehd1, with no ortholog in the Arabidopsis genome). On the other hand, under long-day (LD) conditions, flowering is delayed by the repressive function of Hd1 on FT-like genes and by downregulation of Ehd1 by the flowering repressor Ghd7 -a unique pathway in rice. We report here that an early heading date 3 (ehd3) mutant flowered later than wild-type plants, particularly under LD conditions, regardless of the Hd1-deficient background. Map-based cloning revealed that Ehd3 encodes a nuclear protein that contains a putative transcriptional regulator with two plant homeodomain (PHD) finger motifs. To identify the role of Ehd3 within the gene regulatory network for rice flowering, we compared the transcript levels of genes related to rice flowering in wild-type plants and ehd3 mutants. Increased transcription of Ghd7 under LD conditions and reduced transcription of downstream Ehd1 and FTlike genes in the ehd3 mutants suggested that Ehd3 normally functions as an LD downregulator of Ghd7 in floral induction. Furthermore, Ehd3 ghd7 plants flowered earlier and show higher Ehd1 transcript levels than ehd3 ghd7 plants, suggesting a Ghd7-independent role of Ehd3 in the upregulation of Ehd1. Our results demonstrate that the PHD-finger gene Ehd3 acts as a promoter in the unique genetic pathway responsible for photoperiodic flowering in rice.

Intense research has been carried out in recent decades to develop stimuli-responsive chromic materials [1][2][3][4] for application in smart windows, displays, and switches. To try to address the demand for these applications, many researchers have focused on materials capable of being tuned into a variety of colors by means of external stimuli. Photonic crystals that are three-dimensionally periodic on a length scale comparable to the wavelength of light must be considered promising candidates for stimuli-responsive, full-color chromic materials. The color of the crystals is caused by a photonic bandgap (PBG) that forbids the propagation of electromagnetic waves in a certain frequency range. [5,6] It is technically possible to control the energy levels in the PBG by changing the periodicity and the average dielectric constant of the photonic crystals. Indeed, a close-packed colloidal crystal (CCC), which is selfassembled from monodisperse colloidal particles, offers a simple route to the fabrication of photonic crystals and can produce many desired colors. [7][8][9][10] The CCC appears to be a powerful tool for preparing stimuli-responsive chromic materials. [11][12][13][14][15] Since a face-centered cubic (fcc) structure is generally the most energetically stable for the CCC, [16] and the CCC we prepared is oriented with its (111) axis parallel to a supporting glass substrate, the peak position of the PBG (k max ) for the CCC is obtained by [10] where d is the diameter of the colloidal particles used, m is the order of the Bragg reflection, n a is the refractive index of the CCC, [17] and h is the angle measured from the normal to the plane of the CCC. Under normal incidence, Equation 1 can be rewritten as follows:As noted above, Equation 2 shows that changing the periodicity and the average dielectric constant, that is, the values of d and n a , respectively, can control the peak value. Thus, the size of the particles and the dielectric constants of all building blocks forming the CCC are known as the two determining factors of the PBG. If we attempt to obtain a CCC displaying full color, that is, exhibiting a change in the peak value from 400 to 800 nm, by just changing n a , the value of n a must be changed by a factor of two. It is considerably difficult to accomplish such a major change in the refractive indices of materials by applying external stimuli. Indeed, there have been several reports on the development of stimuli-responsive photonic crystals by changing n a in response to external stimuli. One of the simplest and most inexpensive methods is the application of an opal or inverse opal infiltrated with liquid crystal. [18][19][20] An applied electric field can change the orientation of the molecules in the liquid crystal and, thus, affect its optical properties between one state, in which the incident light is substantially transmitted, to another state, in which the incident light is substantially diffracted. This behavior affects the average refractive index of the liquid crystal, and the positi...