Chlorination-Mediated π-π Stacking Enhances the Photodynamic Properties of a NIR-II Emitting Photosensitizer with Extended Conjugation.

NIR-II-emitting photosensitizers (PSs) have attracted great research interest due to their promising clinical applications in imaging-guided photodynamic therapy (PDT). However, it is still challenging to realize highly efficient PDT on NIR-II PSs. In this work, we develop a chlorination-mediated π-π organizing strategy to improve the PDT of a PS with conjugation-extended A-D-A architecture. The significant dipole moment of the carbon-chlorine bond and the strong intermolecular interactions of chlorine atoms bring on compact π-π stacking in the chlorine-substituted PS, which facilitates energy/charge transfer and promotes the photochemical reactions of PDT. Consequently, the resultant NIR-II emitting PS exhibits a leading PDT performance with a yield of reactive oxygen species higher than that of previously reported long-wavelength PSs. These findings will enlighten the future design of NIR-II emitting PSs with enhanced PDT efficiency.

Basic helix-loop-helix transcription factor PxbHLH02 enhances drought tolerance in Populus (Populus simonii × P. nigra).

The basic helix-loop-helix (bHLH) transcription factors (TFs) are involved in plant morphogenesis and various abiotic and biotic stress responses. However, further exploration is required of drought-responsive bHLH family members and their detailed regulatory mechanisms in Populus. Two bHLH TF genes, PxbHLH01/02, were identified in Populus simonii × P. nigra and cloned. The aim of this study was to examine the role of bHLH TFs in drought tolerance in P. simonii × P. nigra. The results showed that the amino acid sequences of the two genes were homologous to Arabidopsis thaliana UPBEAT1 (AtUPB1) and overexpression of PxbHLH01/02 restored normal root length in the AtUPB1 insertional mutant (upb1-1). The PxbHLH01/02 gene promoter activity analysis suggested that they were involved in stress responses and hormone signaling. Furthermore, Arabidopsis transgenic lines overexpressing PxbHLH01/02 exhibited higher stress tolerance compared with the wild-type. Populus simonii × P. nigra overexpressing PxbHLH02 increased drought tolerance and exhibited higher superoxide dismutase and peroxidase activities, lower H2O2 and malondialdehyde content, and lower relative conductivity. The results of transcriptome sequencing (RNA-seq) and quantitative real-time PCR suggested that the response of PxbHLH02 to drought stress was related to abscisic acid (ABA) signal transduction. Overall, the findings of this study suggest that PxbHLH02 from P. simonii × P. nigra functions as a positive regulator of drought stress responses by regulating stomatal aperture and promoting ABA signal transduction.

The phosphoinositide-specific phospholipase C1 modulates flowering time and grain size in rice.

MAIN CONCLUSION: Preferential expression of OsPLC1 is detected at the heading stage of rice, OsPLC1 overexpression results in early flowering, increased-grain size and yield; however, opposing phenotypes produced in the osplc1 mutants. Abstract: The importance of phospholipase C (PLC) in plant development has been demonstrated in several studies. OsPLC1, a member of PI-PLC in rice, although its role in the response to salt stress of rice seedlings has been reported, its functions in the growth and development of rice is elusive. Here, we report that OsPLC1 expression could be detectable in various tissues throughout the developmental stages of rice, and the highest expression level of OsPLC1 was detected at the heading stage. OsPLC1 overexpression (OE) produced rice plants with early flowering, whereas OsPLC1 loss-of-function led to delay in flowering. The expression levels of subset genes, which are involved in the control of flowering time in rice, were altered in the plants of OE and osplc1. In addition, the enlargement of grain size was observed in OE plants, however, the reduction of grain size was noticed in osplc1 mutants. The increase in the grain size and the grain yield of OE lines were associated with the improvement of cell length and expression levels of a set of genes related to cell expansion, contrarily, the decrease in osplc1 mutant grain size and yield were linked to declined cell length and expression levels of related genes. No significant differences, in terms of the grain quality of mature seeds, were found in OE and osplc1 mutants, with compared to those in Nipponbare (Nip). In summary, our study suggests that OsPLC1 could modulate rice flowering time and grain size.

Morphologically Tunable Supramolecular Rectangular Microsheet and Microsaw Constructed by Hierarchical Self-Assembly Based on Hydrogen Bonds.

An amino acid derivative, thiophene (TDAV), as new building blocks for 2D supramolecular assembly is designed. Various square and rectangular microsheets are achieved and the aspect ratios are precisely regulated by controlling the polarity of cosolvent or water content. By the introduction of chirality, the novel microsaw is also achieved. It provides a new approach to prepare various kinds of unique supramolecular 2D materials with controllable shapes and sizes for future biological applications.

Oligomeric Acceptor: A "Two-in-One" Strategy to Bridge Small Molecules and Polymers for Stable Solar Devices.

Oligomeric acceptors are expected to combine the advantages of both highly developed small molecular and polymeric acceptors. However, organic solar cells (OSCs) based on oligomers lag far behind due to their slow development and low diversity. Here, three oligomeric acceptors were produced through oligomerization of small molecules. The dimer dBTICγ-EH achieved the best power conversion efficiencies (PCEs) of 14.48 % in bulk heterojunction devices and possessed a T80 (80 % of the initial PCE) lifetime of 1020 h under illumination, which were far better than that of small molecular and polymeric acceptors. More excitingly, it showed PCEs of 16.06 % in quasi-planar heterojunction (Q-PHJ) devices which is the highest value OSCs using oligomeric acceptors to date. These results suggest that oligomerization of small molecules is a promising strategy to achieve OSCs with optimized performance between the high efficiency and durable stability, and offer oligomeric materials a bright future in commercial applications.

The rice phosphoinositide-specific phospholipase C3 is involved in responses to osmotic stresses via modulating ROS homeostasis.

Four members of phosphoinositide-specific phospholipase C (PI-PLC) are predicted in rice genome. Although the involvement of OsPLC1 and OsPLC4 in the responses of rice to salt and drought stresses has been documented, the role of OsPLC3 in which, yet, is elusive. Here, we report that OsPLC3 was ubiquitously expressed in various tissues during the development of rice. The expression of YFP-tagged OsPLC3 was observed at the plasma membrane (PM), cytoplasm and nucleus of rice protoplasts, onion epidermal cells and tobacco leaves. The catalytic activity of OsPLC3 was measured using the thin-layer chromatography (TLC) method. The inhibition of OsPLC3 expression was detected in the treatments of NaCl and mannitol. Overexpression (OE) of OsPLC3 produced plants showing more sensitive to osmotic stresses when they were compared to the wild-type (HJ) and osplc3 mutants, the phenomena such as decreased plant fresh weight and increased water loss rate (WLR) were observed. Under the treatment of NaCl or mannitol, expressions of a subset osmotic stress-related genes were altered, in both OE and osplc3 mutant lines. In addition, the expressions and the enzyme activities of reactive oxygen species (ROS) scavengers were significantly decreased in OE lines, leading to over-accumulation of ROS together with less osmotic adjustment substances including proline, soluble sugars and soluble proteins in OE plants which caused the growth inhibition. Thus, our results suggested that, via modulating ROS homeostasis, OsPLC3 is involved in responses to the osmotic stress in rice.

ABA-INDUCED expression 1 is involved in ABA-inhibited primary root elongation via modulating ROS homeostasis in Arabidopsis.

To endure environmental stresses, plants have evolved complex regulatory mechanisms involving phytohormones, including abscisic acid (ABA). The function of the plant-specific AT-rich sequence zinc-binding protein (PLATZ) family has not yet been extensively characterized in Arabidopsis (Arabidopsis thaliana). In this report, we evaluated the function of a putative member of the PLATZ family in Arabidopsis, ABA-INDUCED expression 1 (AIN1). We determined that AIN1 expression was induced by ABA and abiotic stresses. AIN1 overexpression (OE) enhanced ABA sensitivity and inhibited primary root elongation, but reduced expression of AIN1 in RNA interference (RNAi) plants produced roots less sensitive to ABA. When treated with ABA, we observed a reduction of meristem size and over-accumulation of reactive oxygen species (ROS) at the root tips of OE lines, demonstrating the importance of AIN1 in plant responses to ABA. A set of ROS scavenger genes showed reduced expression in the OE lines but improved in the RNAi plants relative to Col-0. In addition, we report that exogenous application of reduced glutathione (GSH) rescued the root growth defects seen in AIN1 overexpression lines treated with ABA. In summary, our results suggest that Arabidopsis AIN1 is involved in ABA-mediated inhibition of root elongation by modulating ROS homeostasis.

Molecular cloning and functional analysis of 4-Coumarate:CoA ligase 4(4CL-like 1)from Fraxinus mandshurica and its role in abiotic stress tolerance and cell wall synthesis.

BACKGROUND: Four-Coumarate:CoA ligase gene (4CL) plays multiple important roles in plant growth and development by catalyzing the formation of CoA ester. 4CL belongs to the plant phenylpropane derivative, which is related to the synthesis of flavonoids and lignin and is a key enzyme in the biosynthetic pathway. RESULTS: In this study, 12 4CL genes of Fraxinus mandschurica were identified and named Fm4CL1-Fm4CL12, respectively. The analysis of the expression pattern of Fm4CL genes indicate that Fm4CL-like 1 gene may play a role in the lignin synthesis pathway. Our study indicate that overexpression of Fm4CL-like 1 increases the lignin content of transgenic tobacco by 39.5% compared to WT, and the S/G ratio of transgenic tobacco increased by 19.7% compared with WT. The xylem cell layer of transgenic line is increased by 40% compared to WT, the xylem cell wall thickness increased by 21.6% compared to the WT. Under mannitol-simulated drought stress, the root length of transgenic tobacco is 64% longer than WT, and the seed germination rate of the transgenic lines is 47% higher than that of WT. In addition, the H2O2 content in the transgenic tobacco was 22% lower than that of WT, while the POD and SOD content was higher than WT by 30 and 24% respectively, which showed Fm4CL-like 1 affect the accumulation of reactive oxygen species (ROS). The MDA content and relative conductivity was 25 and 15% lower than WT, respectively. The water loss rate is 16.7% lower than that of WT. The relative expression levels of stress-related genes NtHAK, NtAPX, NtCAT, NtABF2, and NtZFP were higher than those of WT under stress treatment. The stomatal apertures of OE (Overexpression) were 30% smaller than those of WT, and the photosynthetic rate of OE was 48% higher than that of WT. These results showed that the overexpression line exhibited stronger adaptability to osmotic stress than WT. CONCLUSIONS: Our results indicate that Fm4CL-like 1 is involved in secondary cell wall development and lignin synthesis. Fm4CL-like 1 play an important role in osmotic stress by affecting cell wall and stomatal development.

Gut Microbiota Are Associated With Psychological Stress-Induced Defections in Intestinal and Blood-Brain Barriers.

Altered gut microbiota has been identified during psychological stress, which causes severe health issues worldwide. The integrity of the intestinal barrier and blood-brain barrier regulates the process of bacterial translocation and can supply the nervous system with real-time information about the environment. However, the association of gut microbiota with psychological stress remains to be fully interpreted. In this study, we established a psychological stress model using an improved communication box and compared the expression of tight junction proteins in multiple regions of the intestinal (duodenum, jejunum, ileum) and blood-brain (amygdala, hippocampus) barriers between model and control rats. We also conducted fecal microbiota analysis using 16S rRNA gene sequencing. Expression levels of the stress-related indicators adrenocorticotropic hormone, NR3C1,2, and norepinephrine were increased in the model group compared to control group. Psychological stress reduced brain and intestinal levels of tight junction proteins, including claudin5, occludin, α-actin, and ZO-1. Microbiota analysis revealed elevated microbial diversity and fecal proportions of Intestinimonas, Catenisphaera, and Globicatella in the model group. Further analysis indicated a negative correlation of Allisonella and Odoribacter, as well as a positive correlation of norank_f__Peptococcaceae, Clostridium_sensu_stricto_1, and Coprococcus_2, with claudin5, occludin, α-actin, and ZO-1. Our use of a rodent model to explore the association between compromised intestinal and blood-brain barriers and altered fecal microbiota under psychological stress improves our understanding of the gut-brain axis. Here, cues converge to control basic developmental processes in the intestine and brain such as barrier function. This study provides new directions for investigating the pathogenesis of emotional disorders and the formulation of clinical treatment.

Molecular cloning and functional analysis of a UV-B photoreceptor gene, BpUVR8 (UV Resistance Locus 8), from birch and its role in ABA response.

As a photoreceptor specifically for UV-B light, UVR8 gene plays an important role in the photomorphogenesis and developmental growth of plants. In this research, we isolated the UVR8 gene from birch, named BpUVR8 (AHY02156). BpUVR8 overexpression rescued the uvr8 mutant phenotype using functional complementation assay of BpUVR8 in Arabidopsis uvr8 mutants, which showed that the function of UVR8 is conserved between Arabidopsis and birch. The expression analysis of BpUVR8 indicated that this gene is expressed in various tissues, but its expression levels in leaves are higher than in other organs. Moreover, abiotic stress factors, such as UV-B, salinity, and abscisic acid (ABA) can induce the expression of BpUVR8 gene. Interestingly, the analysis of promoter activity indicated that BpUVR8 promoter not only has the promoting activity but can also respond to the induction of abiotic stress and ABA signal. So, we analyzed its function in ABA response via transgenic UVR8 overexpression in Arabidopsis. The BpUVR8 enhances the susceptibility to ABA, which indicates that BpUVR8 is regulated by ABA and can inhibit seed germination. The root length of 20-day-old 35S::BpUVR8/WT transgenic plants was 18% reduced as compared to the wild-type under the ABA treatment. The membrane of the BpUVR8-overexpressing in Arabidopsis thaliana was the most damaged after ABA treatment and 35S::BpUVR8/WT transgenic plant was more sensitive to ABA than the wild type. These results showed that BpUVR8 is a positive regulator in the ABA signal transduction pathway. In the presence of low dose of UV-B, the sensitivity of wild-type and 35S::BpUVR8/WT plants to ABA was reduced. Moreover, BpUVR8 regulates the expression of a subset of ABA-responsive genes, both in Arabidopsis and Betula platyphylla, under the ABA treatment. Our data provide evidence that BpUVR8 is a positive regulator in the UV-B-induced photomorphogenesis in plants. Moreover, we propose from this research that BpUVR8 might have an important role in integrating plant growth and ABA signaling pathway.

Total syntheses of schilancidilactones A and B, schilancitrilactone A, and 20-epi-schilancitrilactone A via late-stage nickel-catalyzed cross coupling.

The first total syntheses of schilancidilactones A and B, schilancitrilactone A, and 20-epi-schilancitrilactone A have been accomplished using a nickel-catalyzed cross coupling of alkyl bromide with vinyl stannane as the final step. The other key steps include late-stage C(sp3)-H bromination, the oxidative cleavage of a diol to provide the requisite ketone and ester for schilancidilactones A and B, and Dieckmann-type condensation to generate the A ring of schilancitrilactone A and 20-epi-schilancitrilactone A.

Synthesis of oligo-fructopyranoside with difructopyranosyl N-phenyltrifluoroacetimidate donor.

The hexa-fructopyranoside was synthesized with N-phenyltrifluoroacetimidate glycosylation. The synthesis was achieved by regioselective glycosylation on the 1-OH of fructopyranosyl acceptor. Fructosyl oligosaccharides were elongated with ß-(2 â†’ 1)-difructopyranosyl unit in every two steps, without any further protection/deprotection step. This work proved N-phenyltrifluoroacetimidate glycosylation a practical method for oligo-fructopyranoside synthesis.

Total synthesis of schilancitrilactones†b and C.

The first total syntheses of schilancitrilactones B and C have been accomplished in 17 steps (longest linear sequence) from commercially available materials. Key steps include an intramolecular radical cyclization to provide the seven-membered ring, late-stage iodination, and an intermolecular radical addition reaction to complete the total synthesis.