Regulation of the growth and photosynthesis of cherry tomato seedlings by different light irradiations of light emitting diodes (LED)

The growth and photosynthetic characteristics of cherry tomato seedlings were investigated under seven light irradiations such as dysprosium lamps (white light; control, C), red light emitting diodes (LEDs) (R), blue LEDs (B), orange LEDs (O), green LEDs (G), red and blue LEDs (RB) and red, blue and green LEDs (RBG) with the same photosynthetic photon flux density (about 320 μmol m-2 s-1) for 30 days. Morphological appearances of seedlings were significantly different between light treatments, that is, the plants under RB and RBG were shorter and stronger than those under C, while those under O, G and R were higher and weaker. The higher carbohydrate contents were in plants containing blue treatment, B, RB and RBG. Photosynthetic pigments were shown to have significant difference under respective light irradiations of LEDs. The higher photosynthetic pigments were in leaves of seedlings containing blue light treatment, RBG, RB, B, C and G treatments, the lower the pigments were in those with R and O treatments. Net photosynthesis (Pn) was the highest in leaves of seedlings with RB and RBG and the lowest in those with G. Compared with C treatment, light compensation point and light saturation point of seedlings with R, RB and RBG increased, but those with O and G decreased. Electron transport rate (ETR), quantum efficiency of photosystem II photochemistry (ΦPSII), photochemical quenching (qP) and efficiency of excitation energy capture by open PSII reaction centres (Fv′/Fm′) in seedlings with B, RB and RBG treatments were significantly greater than those of the other treatments. Taken together, RB and RBG of LEDs were shown to be beneficial factors for the growth and photosynthesis in cherry tomato seedlings.Key words: Light-emitting diode (LED), light quality, cherry tomato, growth, photosynthetic characteristics

First-principles investigation of electronic, optical, mechanical and heat transport properties of pentadiamond: A comparison with diamond

Pentadiamond is a carbon allotrope consisting of hybrid sp2 and sp3 atoms, which has been predicted to be stable and synthesizable. In this work we employ first-principles calculations to explore the electronic structure, optical characteristics, mechanical response and lattice thermal conductivity of pentadiamond, performing a direct comparison with the corresponding properties in diamond. The HSE06 density functional predicts indirect electronic band gaps for pentadiamond and diamond with values of 3.58 eV and 5.27 eV, respectively. Results for optical characteristics reveal pentadiamond's large absorption in the middle UV region, where diamond does not absorb light, consistent with the smaller band gap of pentadiamond. The elastic modulus and tensile strength of pentadiamond are found to be 496 GPa and 60 GPa, respectively, considerably lower than the corresponding values for diamond. The lattice thermal conductivity is examined by solving the Boltzmann transport equation, with anharmonic force constants evaluated via state-of-the-art machine-learning interatomic potentials. We predict a thermal conductivity of 427 W/m-K for pentadiamond, less than one fifth of the corresponding quantity for diamond. Our results provide a useful vision of the intrinsic properties of pentadiamond, but also highlight some of its disadvantages in mechanical strength and heat conduction when compared to diamond

Alternative Use of DNA Binding Domains by the Neurospora White Collar Complex Dictates Circadian Regulation and Light Responses

In the Neurospora circadian system, the White Collar complex (WCC) of WC-1 and WC-2 drives transcription of the circadian pacemaker gene frequency (frq), whose gene product, FRQ, as a part of the FRQ-FRH complex (FFC), inhibits its own expression. The WCC is also the principal Neurospora photoreceptor; WCC-mediated light induction of frq resets the clock, and all acute light induction is triggered by WCC binding to promoters of light-induced genes. However, not all acutely light-induced genes are also clock regulated, and conversely, not all clock-regulated direct targets of WCC are light induced; the structural determinants governing the shift from WCC\u27s dark circadian role to its light activation role are poorly described. We report that the DBD region (named for being defective in binding DNA), a basic region in WC-1 proximal to the DNA-binding zinc finger (ZnF) whose function was previously ascribed to nuclear localization, instead plays multiple essential roles assisting in DNA binding and mediating interactions with the FFC. DNA binding for light induction by the WCC requires only WC-2, whereas DNA binding for circadian functions requires WC-2 as well as the ZnF and DBD motif of WC-1. The data suggest a means by which alterations in the tertiary and quaternary structures of the WCC can lead to its distinct functions in the dark and in the light

Exposure to NO2, CO, and PM2.5 is linked to regional DNA methylation differences in asthma.

Background:DNA methylation of CpG sites on genetic loci has been linked to increased risk of asthma in children exposed to elevated ambient air pollutants (AAPs). Further identification of specific CpG sites and the pollutants that are associated with methylation of these CpG sites in immune cells could impact our understanding of asthma pathophysiology. In this study, we sought to identify some CpG sites in specific genes that could be associated with asthma regulation (Foxp3 and IL10) and to identify the different AAPs for which exposure prior to the blood draw is linked to methylation levels at these sites. We recruited subjects from Fresno, California, an area known for high levels of AAPs. Blood samples and responses to questionnaires were obtained (n = 188), and in a subset of subjects (n = 33), repeat samples were collected 2 years later. Average measures of AAPs were obtained for 1, 15, 30, 90, 180, and 365 days prior to each blood draw to estimate the short-term vs. long-term effects of the AAP exposures. Results:Asthma was significantly associated with higher differentially methylated regions (DMRs) of the Foxp3 promoter region (p = 0.030) and the IL10 intronic region (p = 0.026). Additionally, at the 90-day time period (90 days prior to the blood draw), Foxp3 methylation was positively associated with NO2, CO, and PM2.5 exposures (p = 0.001, p = 0.001, and p = 0.012, respectively). In the subset of subjects retested 2 years later (n = 33), a positive association between AAP exposure and methylation was sustained. There was also a negative correlation between the average Foxp3 methylation of the promoter region and activated Treg levels (p = 0.039) and a positive correlation between the average IL10 methylation of region 3 of intron 4 and IL10 cytokine expression (p = 0.030). Conclusions:Short-term and long-term exposures to high levels of CO, NO2, and PM2.5 were associated with alterations in differentially methylated regions of Foxp3. IL10 methylation showed a similar trend. For any given individual, these changes tend to be sustained over time. In addition, asthma was associated with higher differentially methylated regions of Foxp3 and IL10