Diurnal RNAPII-tethered chromatin interactions are associated with rhythmic gene expression in rice

Background: The daily cycling of plant physiological processes is speculated to arise from the coordinated rhythms of gene expression. However, the dynamics of diurnal 3D genome architecture and their potential functions underlying the rhythmic gene expression remain unclear. Results: Here, we reveal the genome-wide rhythmic occupancy of RNA polymerase II (RNAPII), which precedes mRNA accumulation by approximately 2 h. Rhythmic RNAPII binding dynamically correlates with RNAPII-mediated chromatin architecture remodeling at the genomic level of chromatin interactions, spatial clusters, and chromatin connectivity maps, which are associated with the circadian rhythm of gene expression. Rhythmically expressed genes within the same peak phases of expression are preferentially tethered by RNAPII for coordinated transcription. RNAPII-associated chromatin spatial clusters (CSCs) show high plasticity during the circadian cycle, and rhythmically expressed genes in the morning phase and non-rhythmically expressed genes in the evening phase tend to be enriched in RNAPII-associated CSCs to orchestrate expression. Core circadian clock genes are associated with RNAPII-mediated highly connected chromatin connectivity networks in the morning in contrast to the scattered, sporadic spatial chromatin connectivity in the evening; this indicates that they are transcribed within physical proximity to each other during the AM circadian window and are located in discrete “transcriptional factory” foci in the evening, linking chromatin architecture to coordinated transcription outputs. Conclusion: Our findings uncover fundamental diurnal genome folding principles in plants and reveal a distinct higher-order chromosome organization that is crucial for coordinating diurnal dynamics of transcriptional regulation

Lignin Synthesis, Affected by Sucrose in Lotus (Nelumbo nucifera) Seedlings, Was Involved in Regulation of Root Formation in the Arabidopsis thanliana

Adventitious roots (ARs) have an unmatched status in plant growth and metabolism due to the degeneration of primary roots in lotuses. In the present study, we sought to assess the effect of sucrose on ARs formation and observed that lignin synthesis was involved in ARs development. We found that the lignification degree of the ARs primordium was weaker in plants treated with 20 g/L sucrose than in 50 g/L sucrose treatment and control plants. The contents of lignin were lower in plants treated with 20 g/L sucrose and higher in plants treated with 50 g/L sucrose. The precursors of monomer lignin, including p-coumaric acid, caffeate, sinapinal aldehyde, and ferulic acid, were lower in the GL50 library than in the GL20 library. Further analysis revealed that the gene expression of these four metabolites had no novel difference in the GL50/GL20 libraries. However, a laccase17 gene (NnLAC17), involved in polymer lignin synthesis, had a higher expression in the GL50 library than in the GL20 library. Therefore, NnLAC17 was cloned and the overexpression of NnLAC17 was found to directly result in a decrease in the root number in transgenic Arabidopsis plants. These findings suggest that lignin synthesis is probably involved in ARs formation in lotus seedlings.</jats:p

Synthesis of Lauric-Myristic Acid/Activated Carbon Composite as a New Shape-Stabilized Energy Storage Material

In this work, a new composite phase change material (CPCM) with lauric-myristic acid (LA-MA) eutectic as PCM and activated carbon (AC) was used as supporting material with four different mass ratios of 5.0:5.0, 5.5:4.5, 6.0:4.0, and 6.5:3.5, respectively. The properties and microstructure of LA-MA/AC were analyzed by some characterization methods. The results show that the composite process of LA-MA eutectic and AC was a simple physical mixing and no new chemical bonds were found. The fusion and freeze temperature, enthalpy of the samples were measured by differential scanning calorimetry (DSC), and the residual weight of the samples was analyzed by thermogravimeter (TGA). It was shown that the fusion and freeze temperature of LA-MA eutectic separately were 32.42 ℃ and 33.63 ℃, and its fusion enthalpy and freeze enthalpy were 152.64 J/g and 148.8 J/g, respectively. TGA data shows that the thermal stability of LA-MA eutectic was obviously improved by adding AC as a support material. The results of this study can be available for reference to solar energy storage applications.</jats:p

Lignin Synthesis, Affected by Sucrose in Lotus (Nelumbo nucifera) Seedlings, Was Involved in Regulation of Root Formation in the Arabidopsis thanliana

Adventitious roots (ARs) have an unmatched status in plant growth and metabolism due to the degeneration of primary roots in lotuses. In the present study, we sought to assess the effect of sucrose on ARs formation and observed that lignin synthesis was involved in ARs development. We found that the lignification degree of the ARs primordium was weaker in plants treated with 20 g/L sucrose than in 50 g/L sucrose treatment and control plants. The contents of lignin were lower in plants treated with 20 g/L sucrose and higher in plants treated with 50 g/L sucrose. The precursors of monomer lignin, including p-coumaric acid, caffeate, sinapinal aldehyde, and ferulic acid, were lower in the GL50 library than in the GL20 library. Further analysis revealed that the gene expression of these four metabolites had no novel difference in the GL50/GL20 libraries. However, a laccase17 gene (NnLAC17), involved in polymer lignin synthesis, had a higher expression in the GL50 library than in the GL20 library. Therefore, NnLAC17 was cloned and the overexpression of NnLAC17 was found to directly result in a decrease in the root number in transgenic Arabidopsis plants. These findings suggest that lignin synthesis is probably involved in ARs formation in lotus seedlings

NnLAC17, a Gene Related to Lignin Synthesis, is Involved in Adventitious Root Formation in the Seedlings of Lotus (Nelumbo Nucifera Gaertn)

Abstract BarkgroundAdventitious roots (ARs), which are considered as an important member of root system, have an unmatched status in plant growth and metabolism due to the degeneration of primary roots in lotus. The regulation of AR formation was previously revealed and multiple factors were recognized to be involved in this biological process. ResultsIn the present study, we sought to assess the effect of sucrose on AR formation. Based on our results, lignin metabolism, which is regulated by the sucrose signal transduction pathway, is involved in AR development. The lignification degree of the AR primordium was weaker in plants treated with 20 g/L sucrose than in control plants. However, based on the microstructural observation of the AR developmental process, 50 g/L sucrose promoted the lignification process. Lignin content, including monomer and polymer lignin, was determined in the present study. Compared with control plants, the monomer (containing 30%–45% S type and 55%–70% G type) and polymer lignin contents were lower in plants treated with 20 g/L sucrose and higher in plants treated with 50 g/L sucrose. The precursors of monomer lignin were identified in four libraries of differential developmental stages in seedlings using LC-MS/MS technique. The contents of four metabolites, including p-coumaric acid, caffeate, sinapinal aldehyde and ferulic acid for monomer lignin synthsis were lower in the GL50 library than in the GL20 library. Further analysis revealed that the gene expression of these four metabolites had no novel difference in the GL50/GL20 libraries. However, NnLAC17, a gene involved in polymer lignin synthesis, had a higher expression in the GL50 library than in the GL20 library. ConclusionsTherefore, NnLAC17 was cloned, and the overexpression of NnLAC17 was found to directly result in a decrease in AR number in transgenic Arabidopsis plants. These findings suggest that NnLAC17, which is relevant to lignin synthesis, is involved in AR formation in lotus seedlings.</jats:p

Preparation and Thermal Properties of Hexadecanol-Myristic Acid Eutectics/ Activated Carbon Composites as Shape-stabilized Phase Change Materials in Thermal Energy Storage

In this study, hexadecanol-myristic acid (HD-MA) binary eutectic mixtures were adsorbed into activated carbon (AC) to prepare the composite phase transition materials(CPCMs). In the hexadecanol-myristic acid/activated carbon (HD-MA/AC) composites, the mixture of HD–MA acted as the phase change energy storage material and the AC was used as the matrix supporting material. Activated carbon is a kind of inorganic supporting material, which has developed pore structure, strong adsorption, high mechanical strength, corrosion resistance and good thermal stability. As the supporting material, activated carbon was helpful to prevent the eutectics from leakage. The chemical structure and crystal phase structure of HD-MA/AC composites were tested by FT-IR and XRD. The microstructure of the composites was observed through field emission scanning electron microscopy (FE-SEM). It was found that the organic binary eutectics were adsorbed on the surface and inside by activated carbon. Thermal properties of the composites were measured by differential scanning calorimetry (DSC). The results of performance test demonstrated that the satisfactory sample CPCM1 melted at 42.38 °C with latent heat of 76.24 J/g and solidified at 38.32 °C with latent heat of 67.08 J/g. The test results of TGA indicated that the prepared composites of hexadecanol-myristic acid/activated carbon possessed great thermal stability and high reliability. It is predicted that the shape-stabilized HD-MA/AC composites have great potential for thermal energy storage.</jats:p

Enhanced Thermal Performance of Composite Phase Change Materials Based on Hybrid Graphene Aerogels for Thermal Energy Storage

Thermal conductivity and latent heat are crucial performance parameters for phase change materials (PCMs) in thermal energy storage. To enhance the thermal performance of PCMs, with the help of graphene oxide (GO) acting as a dispersing agent, well-defined hybrid graphene aerogels (HGAs) with a three-dimensional (3D) porous structure were successfully synthesized by hydrothermal reaction of GO and graphene nanoplatelets (GNPs). GNPs, dispersing uniformly along the interconnecting graphene network, acted as thermal conductive fillers and supporting materials. Palmitic acid (PA) was impregnated into the HGA by vacuum forces. It was found that the thermal conductivity of the PA/HGA was enhanced without compromising heat storage capacity. Compared with PA, the PA/HGA with 4.2 wt% GNPs exhibited enhanced thermal conductivity of 2.1 W/mK and high latent heat of 206.2 J/g simultaneously. The PA/HGA with good thermal performance has potential applications in thermal energy storage