Xie, Mingtang
Chen, Hongyu
Huang, Ling
O'Neil, Ryan C
Shokhirev, Maxim N
Ecker, Joseph R
Cytokinin fulfills its diverse roles in planta through a series of transcriptional responses. We identify the in vivo DNA binding site profiles for three genetically redundant type-B ARABIDOPSIS RESPONSE REGULATORS (B-ARRs): ARR1, ARR10, and ARR12. The expression and genome-wide DNA binding locations of the three B-ARRs extensively overlap. Constructing a primary cytokinin response transcriptional network reveals a recurring theme of widespread cross-regulation between the components of the cytokinin pathway and other plant hormone pathways. The B-ARRs are found to have similar DNA binding motifs, though sequences flanking the core motif were degenerate. Cytokinin treatments amalgamate the three different B-ARRs motifs to identical DNA binding signatures (AGATHY, H(a/t/c), Y(t/c)) which suggests cytokinin may regulate binding activity of B-ARR family members. Furthermore, we find that WUSCHEL, a key gene required for apical meristem maintenance, is a cytokinin-dependent B-ARR target gene, demonstrating the importance of the cytokinin transcription factor network in shoot development.=20
The transfer of plastid DNA sequences into plant nuclear genomes plays an important role in the genomic evolution of plants. The abundance of nuclear-localized plastid DNA (nupDNA) correlates positively with nuclear genome size, but the genetic content of nupDNA remains unknown. In this mini review, we analyzed the number of nuclear-localized plastid gene fragments in known plant genomic data. Our analysis suggests that nupDNAs are abundant in plant nuclear genomes and can include multiple complete copies of protein-coding plastid genes. Mutated nuclear copies of plastid genes contained synonymous and nonsynonymous substitutions. We estimated the age of the nupDNAs based on the time when each integration occurred, which was calculated by comparing the nucleotide substitution rates of the nupDNAs and their respective plastid genes. These data suggest that there are two distinct age distribution patterns for nupDNAs in plants, and Oryza sativa and Zea mays were found to contain a very high proportion of young nupDNAs. Expressed sequence tags and predicted promoters of nupDNAs were identified, revealing that certain nuclear-localized plastid genes may be functional and that some have undergone positive natural selection pressure. =20
A variety of nanocomposites between metallic nanoparticles and polymers were produced. The attachment pattern of polymer micelles on the metal nanostructures evolved from the full coverage to partially engulfing; i. e. Janus (two-faced) nanoparticles; through tuning the ligand combinations. The basic principle for this achievement is that the surface feature is dictated by competitive chemisorption of hydrophobic and hydrophilic ligands forming segregated patches on the nanostructures; which results in directional self-assembly of amphiphilic diblock copolymer on the hydrophobic ligand coated surface; while leaving the hydrophilic ligand modified surface exposed to the aqueous solution. The generality of this strategy has been demonstrated by creating a broad range of nanocomposties with different metallic cores; different ligand combinations and various amphiphilic diblock copolymers. Also; we further extend this concept for the creation of hollow polymeric structures with openings (at nanoscale); the investigation of the surface-enhanced Raman scattering site distributions on nanospheres and nanorods; and the controlled organization of the nanoparticles into dimers or oligomers.
Zhang, Min
Liu, Jia
Kuang, Ying
Li, Qilin
Chen, Hongyu
Ye, Haifeng
Guo, Li
Xu, Yanglin
Chen, Xueqin
Li, Cao
Jiang, Bingbing
Suitable protection strategies utilized in anticancer drug delivery systems enable carriers to reach their targeted positions and release drugs intracellularly more effectively. In this study, a novel "stealthy'' chitosan (CHI)/mesoporous silica nanoparticle (MSN) based complex system, named DOX@MSN-SS-CHI-PEG, was developed for tumor-triggered intracellular drug release. CHI was applied to block the pores of MSNs to prevent premature drug release, whereas mPEG was grafted on the surface of the nanoparticles via a pH-sensitive benzoic imine linker to protect the carriers. As the pH of solid tumor tissues is slightly lower than that of normal tissues, mPEG could leave the nanoparticles to expose positively charged CHI at the surface, which enabled the nanoparticles to enter cancer cells more easily. The MSNs were covered by CHI via redox-sensitive disulfide bonds. As a result, the carriers could release the drug intercellularly to kill cancer cells owing to the high concentration of glutathione (GSH) in the cytosol. In vitro drug release studies at different GSH concentrations proved the redox-sensitivity of DOX@MSN-SS-CHI-PEG. mPEG leaving studies demonstrated that mPEG could leave the nanoparticles effectively at pH 6.0. The cytotoxicity and cell internalization behavior were also investigated in detail. In conclusion, the novel DOX@MSN-SS-CHI-PEG drug delivery system, which was "stealthy'' in the physiological environment at pH 7.4 because of the protection of mPEG, was "activated'' in weakly acidic tumor tissues to achieve tumor-triggered intracellular drug release; this system has great potential for cancer therapy.
Zou, Weiyong
Wang, Li
Lu, Baoyi
Li, Hong
Chen, Hongyu
The electrochemical assembly of [Ru(bpy)(2)tatp](2+) (where bpy = 2,2'-bipyridine, tatp = 1,4,8,9-tetra-aza-triphenylene) on the multi-walled carbon nanotubes-modified glassy carbon electrode (MWNTs/GC) in the presence of anionic and cationic surfactants has been investigated. A diffusion-controlled wave and three prewaves are exhibited on the differential pulse voltammogram of [Ru(bpy)(2)tatp](2+). The formal potential of the prewaves is found to be much negative than that of the diffusion-controlled wave. An appropriate amount of anionic surfactants including dihexadecyl phosphate (DHP) and deoxyribonucleic acid (DNA) can prompt the assembly of [Ru(bpy)(2)tatp](2+) on the MWNTs/GC electrode by using the method of repetitive voltammetric sweeping. In contrast, cationic surfactant such as hexadecyl trismethyl ammonium chrolide (HTAC) dispersed on the MWNTs surface is found to inhibit the assembly of [Ru(bpy)(2)tatp](2+). Meanwhile, the assembled principle of [Ru(bpy)(2)tatp](2+) on the MWNTs/GC electrode with the participation of surfactants is discussed in detail.
A novel drug delivery system based on arginine-glycine-aspartic acid (RGD)-conjugated graphene quantum dots (GQDs) was synthesized and utilized to load the antitumor drug doxorubicin (DOX) for targeted cancer fluorescence imaging as well as tracking and monitoring drug delivery without the need for external dyes. The inherent stable fluorescence of GQDs enables real-time monitoring of the cellular uptake of the DOX-GQDs-RGD nano-assembly and the consequent release of DOX. The release of DOX demonstrated strong pH dependence and implies hydrogen-bonding interaction between GQDs and DOX, an observation that suggests the possibility for GQDs serving as pH-sensitive drug carriers. As a nanocarrier, GQDs unlinked with DOX were nontoxic to U251 human glioma cells. Compared to free DOX, DOX-GQDs-RGD conjugates demonstrated substantial cytotoxicity to U251 glioma cells within a broad range of DOX concentrations. After applying the GQDs as drug carriers, the drug efficacy of DOX improved without concomitant DOX dosage increases. Cellular uptake results of DOX-GQDs-RGD conjugates indicate that not only DOX but also some GQDs penetrated into cell nuclei after 16 h of incubation. This enhancement combined with efficient nuclear delivery improved the cytotoxicity of DOX dramatically. This type of drug delivery system based on GQDs may find widespread applications in biomedicine. (C) 2017 Published by Elsevier B.V.
Lead sulfate, lead dioxide and lead oxide are the main components of lead paste in a spent lead-acid battery. In addition, there are a few impurities in spent lead paste, which have great influence on the performance of the new battery; therefore, it is necessary to remove them. In this study, a novel approach with low temperature burning and hydrometallurgical processing with NH(4)AC is developed to recover lead from spent lead paste. First, some of the impurities are converted to metal oxides by the calcination of spent lead paste at low temperature. Second, the metal oxides are transformed into soluble sulphates by the reaction between the calcination products and dilute H2SO4 and H2O2 (5.0%). Then, the solids are separated from the solution by filtration; the solids are mainly PbSO4, BaSO4 and CaSO4. NH(4)AC is used as the leaching solution for PbSO4, and CO2 is introduced to obtain pure PbCO3. Under the optimized leaching conditions (leaching temperature at 40 degrees C for 20 min, 10.0 wt% NH(4)AC), the lead recovery ratio is about 99.9%. The calcination product of lead carbonate is PbO, and high-purity lead oxide is obtained. The initial discharge capacity of high-purity lead oxide is about 158 mA h g(-1), and the capacity loss is less than 2% after 80 cycles.
The influence of biochar amended dewatered fresh sewage sludge (DFSS)-wheat straw co-composting on nutrients transformation and end products quality was investigated. This is the first study to examine the biochar applied compost quality with different kg ha (1) TKN on Brassica rapa L. growth. Seven mixtures were composted over 8-weeks period in 130-L reactor using the same DFSS with different concentration of biochar (2%, 4%, 6%, 8%, 12% and 18% on dry weight basis) and without additive added treatment served as control. The results indicated that compost with 8-12% biochar became more humified within 35 days of composting, and the compost maturity parameters also showed that this could be much more feasible approach to increased water-soluble nutrients including NO3, DOC, DON, PO43 ,K+ and Na+, but bioavailability of Cu, Zn, Ni and Pb content reduced as compared to control. Finally, results showed that 8-12% biochar was recommended for DFSS composting and 150 kg ha (1) TKN of compost dosages for organic farming. (C) 2017 Elsevier Ltd. All rights reserved.