Project description:The goal of this work was to investigate the influence of low red to far-red (R:FR) signals generated by a biological weedy and an artificial source of far-red light on the nitrate assimilation pathway in maize. In the absence of direct resource competition, far-red light reflected from neighboring weeds compromises light quality (red to far-red ratio; R/FR) and causes a wide range of morphological and physiological responses at early growth stages of crop plants. This study has investigated the effects of low R/FR light signals on nitrate assimilation in maize seedlings. The transcript levels of genes, metabolites, and activities of enzyme in the nitrate assimilation pathway under a biological and a simulated low R:FR light environment were compared with a high R:FR control environment. Low R:FR signals stimulated nitrate accumulation in maize leaves, which did not appear to result from the upregulation of nitrate transporter genes. A significant reduction in ferredoxin-dependent glutamine:2-oxoglutarate aminotransferase activity appears to play a major role in nitrate accumulation under low R:FR light environments, while activities of other enzymes of the nitrate assimilation pathway remain unchanged.
Project description:PIL5 is a key negative regulator of phytochrome mediated seed germination and PIL5 protein is degraded by red light irradiation through phytochrome. The microarray aimed to find various red light-regulated genes and PIL5-regulated genes in the imbibed seeds. Experiment Overall Design: Col-0 and pil5 seeds were irradiated by far-red light or far-red/red light and then, incubated in the dark for 12 hours. Total three biological replicates were used for the microarray.
Project description:Far-red fluorescent proteins (FPs) are desirable for in vivo imaging because with these molecules less light is scattered, absorbed, or re-emitted by endogenous biomolecules compared with cyan, green, yellow, and orange FPs. We developed a new class of FP from an allophycocyanin α-subunit (APCα). Native APC requires a lyase to incorporate phycocyanobilin. The evolved FP, which we named small ultra-red FP (smURFP), covalently attaches a biliverdin (BV) chromophore without a lyase, and has 642/670-nm excitation-emission peaks, a large extinction coefficient (180,000 M(-1)cm(-1)) and quantum yield (18%), and photostability comparable to that of eGFP. smURFP has significantly greater BV incorporation rate and protein stability than the bacteriophytochrome (BPH) FPs. Moreover, BV supply is limited by membrane permeability, and smURFPs (but not BPH FPs) can incorporate a more membrane-permeant BV analog, making smURFP fluorescence comparable to that of FPs from jellyfish or coral. A far-red and near-infrared fluorescent cell cycle indicator was created with smURFP and a BPH FP.
Project description:To demonstrate the tolerance of mammalian sperm nucleus against extreme environments, mouse spermatozoa were freeze-dried and treated with 95 °C for 1 h or irradiated at over 5 Gy. Although all sperm were ostensibly dead after rehydration, healthy offspring were obtained from recovered sperm nuclei. The normality of those offspring were examined by microarray, and no difference were detected compare to fresh control offspring.
Project description:The absorption of visible light in aquatic environments has led to the common assumption that aquatic organisms sense and adapt to penetrative blue/green light wavelengths, but show little or no response to the more attenuated red/far-red wavelengths. Here we show that two marine diatom species, Phaeodactylum tricornutum and Thalassiosira pseudonana, possess a bona fide red/far-red light sensing phytochrome (DPH) that uses biliverdin as a chromophore and displays accentuated red-shifted absorbance peaks compared to other characterized plant and algal phytochromes. Exposure to both red and far-red light causes changes in gene expression in P. tricornutum and the responses to far-red light disappear in DPH knockout cells, demonstrating that P. tricornutum DPH mediates far-red light signaling. The identification of DPH genes in diverse diatom species widely distributed along the water column further emphasizes the ecological significance of far-red light sensing, raising questions about the sources of far-red light. Our analyses indicate that, although far-red wavelengths from sunlight are only detectable at the ocean surface, chlorophyll fluorescence and Raman scattering can generate red/far-red photons in deeper layers. This study opens up novel perspectives on phytochrome-mediated far-red light signaling in the ocean and on the light sensing and adaptive capabilities of marine phototrophs.